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Ahmed, M. L.; Yudkin, P. L.; Macfarlane, J. A.; McPherson, K.; Dunger, D. B. (1990) Are measurements of height made by health visitors sufficiently accurate for routine screening of growth?. Archives of Diseases of Children 65, 12, 1345-1348.
Abstract: To find out whether measurements of height made by health visitors are sufficiently accurate for use in routine screening of children we carried out an interobserver and intraobserver reliability study. Height measurements were made on a group of 10 children aged 3 years old and 10 aged 4.5 years old by two sets of four health visitors. They used a Microtoise or wall chart and the measurements were compared with those made by a trained auxologist with a Harpenden stadiometer. For a single assessment of height both pieces of equipment gave reasonably accurate results. In a child aged 3 years, with height measured on the Microtoise as 100 cm, the true height could be expected – with 95% probability – to lie between 99.2 cm-101.8 cm. At the age of 4.5 years, if the measurement was 110 cm, the child’s true height could be expected to lie between 108.9 cm and 111.9 cm. The narrowest confidence interval for the growth rate from 3 to 4.5 years was achieved with the Microtoise, taking the mean of three measurements.
We conclude that measurements made by health visitors are sufficiently accurate for routine screening of height, and the use of such measurements for the calculation of height velocity could be improved by more structured training.
Au, G.; Cook, J.; McGill, S. M. (2001) Spinal shrinkage during repetitive controlled torsional, flexion and lateral bend motion exertions. Ergonomics, 44, 4, 373-381.
Abstract: This experiment analyzed the spinal shrinkage due to repetitive exertions confined to each of three separate axes (twist, lateral bend, flexion). While the experiment was performed twice with small technique modifications in the twisting task (and thus two data collections were performed), the essential components were as follows. A total of 20 subjects were loaded with an equal moment of 20 Nm in each of the three axes, on 3 separate days (one axis per day). Subjects performed each task for 20 min at 10 repetitions min (-1), where stadiometer measurements of standing height were taken prior to and immediately following the 20 min exertion.
The twisting task demonstrated significant spinal shrinkage (1.81 and 3.2 mm in the two experiments) between the pre- and post-stature measurements while no clear effect emerged for the other two tasks. These data suggest that repetitive torsional motions impose a larger cumulative loading on the spine when compared with controlled lateral or flexion motion tasks of a similar moment.
Beynon, C. and Reilly, T. (2001) Spinal shrinkage during a seated break and standing break during simulated nursing tasks. Applied Ergonomics 32, 6, 617-622.
Abstract: Prevalence rates for back pain in nurses are comparable to rates of workers in heavy industry. Spinal loading is one factor thought to be associated with the onset of back problems. Loading can be measured indirectly using precision stadiometry, with changes in stature indicating the magnitude of the loading over time. Ten female subjects completed 4 h of simulated nursing activities on two separate occasions. The two trials were identical except that subjects were asked to sit for a 20-min break in one and stand for a 20-min break in the other trial. Heart rate, discomfort, rating of perceived exertion and spinal shrinkage were recorded at various intervals throughout testing. Spinal shrinkage was significantly less during the seated trial than the standing trial (p<0.05). It is suggested that a seated break during a nursing shift may reduce the potential of suffering back problems resulting from spinal loa ding.
Scholl, T. O. and Hediger, M. L. (1993) A review of the epidemiology of nutrition and adolescent pregnancy: maternal growth during pregnancy and its effect on the fetus. J Am Coll Nutrition 12, 2, 101-107.
Abstract: Maternal growth during adolescent pregnancy and its effects on pregnancy outcome have been a source of controversy. Maternal growth during pregnancy has been difficult to quantify because of the tendency of young and older women to "shrink" in stature with pregnancy. In the Camden Study, maternal growth during pregnancy was monitored with the Knee Height Measuring Device, which measures growth of the lower leg, a body segment less susceptible to "shrinkage".
Attempts of other investigators to detect maternal growth during adolescent pregnancy are reviewed here. New data from the Camden Study, also presented, suggest that growing adolescents have infants that weigh less compared to nongrowing adolescents and mature controls (aged 19-29 years). Prior work had suggested that the effects of maternal growth on birth weight were confined to adolescent multiparas. However, with expanded enrollment it was found that infants of growing primiparas and multiparas were both affected. The hypothesis of the competition for nutrients between a still-growing gravida and her fetus is discussed.
Boocock, M. G., Garbutt, G., Linge, K., Reilly, T. and Troup, J. D. (1990) Changes in stature following drop jumping and post-exercise gravity inversion. Medical Sci Sports Exercises 22, 3, 385-390.
Abstract: Spinal shrinkage, measured by changes in stature, is used as an index of spinal loading as alterations reflect changes in intervertebral disc height. Shrinkage induced by various physical activities may be reversed using gravity inversion. The present purpose was to examine the shrinkage induced by a drop jumping regimen and evaluate gravity inversion post-exercise. Eight males, aged 20-31, performed two separate experimental protocols, each on different dates at 1400 h.
Subjects stood for 30 min before undertaking an exercise regimen, consisting of five sets of five drop jumps from a height of 1m, rebounding over a hurdle 0.5 m high. For 20 min, directly following the exercise regimen, subjects on one occasion stood and on a second occasion undertook gravity inversion. Shrinkage was monitored for 40 min after this post-exercise treatment. The stadiometer used to measure shrinkage was accurate to 0.05 mm. The exercise regimen caused a mean shrinkage of 1.68 and 1.81 mm for the two testing sessions. Post-exercise inversion and standing for 20 min increased stature by 5.18 and 0.76 mm, respectively (P < 0.01). The 40-min standing period following inversion caused a rapid loss in stature (4.07 mm). At 30 min into this recovery period, there was no significant difference in shrinkage for either of the regimens.
Results suggest that effects of an inversion treatment are short-lasting.
Cotton, L. M., D. G. O’Connell, et al. (2002). Mismatch of school desks and chairs by ethnicity and grade level in middle school. Work 18(3): 269-80.
Objective: The purpose of this study was to compare anthropometric measurements of children/adolescent (6th grade – 8th grade) and use these measurements to determine fit by ethnicity and grade level across three common classroom desks and chairs.
Design: Eighty-eight Caucasian-American (CA), 65 Mexican-American (MA), and 58 African-American (AA) 6th, 7th, and 8th graders participated in the study (n = 211 students). Students were seated (shoeless) on a horizontal seating surface with an adjustable footrest to obtain 90° angles at the hips, knees, and ankles. Standing height and five seated measurements were obtained using a stadiometer. Desk measurements were obtained from the most common desks used for each grade level. Six measurements (seat height, seat depth, seat slope, desk height, desk clearance, desk slope) were obtained with a tape measure and angle finder. Mismatch was operationalized a priori to determine fit of student dimensions and desks.
Results: Multivariate analysis (SPSS 10.1) revealed significant differences in anthropometric dimensions at each grade level for ethnicity and gender (p < 0.05). Only one 6th grade MA male fit both seat height and depth criteria.
One-way ANOVAs and Scheffe post hoc tests revealed significant differences between fit by ethnicity for chair 1 and chair 2. No students experienced knee/desk clearance problems. Only one student was able to find a desk surface that did not exceed their maximum functional elbow height.
Conclusions: AA’s had longer lower extremity lengths versus their ethnic counterparts at all grade levels. Subjects did not fit chairs and desks regardless of age or ethnicity. Ethnicity played a significant role in seat height fit for two of the three chairs. These disparities may create a generation with an increased incidence of musculoskeletal problems carrying over to adulthood and the adult workplace.
Bonney, R. A. and E. N. Corlett (2002). Head posture and loading of the cervical spine. Applied Ergonomics 33(5): 415-7.
Calculations by Colombini et al. (Ergonomics of Working Postures. Taylor & Francis, London, 1985) showed that a line of gaze below the horizontal would load the cervical spine more than a horizontal gaze. Precision stadiometer tests were run, using seven subjects, to measure the effects on spinal length of different angles of gaze. After 1 h exposure whilst sitting in a controlled posture, there were significant differences in the shrinkage of the spine between the horizontal gaze and the 20° and 40° angles below the horizontal. The increased spinal loading demonstrated by the increase in spinal shrinkage calls into question the recommendations for angle of gaze recommended in textbooks.
Bourne, N. D. and Reilly, T. (1991) Effect of a weightlifting belt on spinal shrinkage. British J Sports Medicine 25, 4, 209-212.
Abstract: Spinal loading during weightlifting results in a loss of stature which has been attributed to a decrease in height of the intervertebral discs – so-called spinal shrinkage. Belts are often used during the lifting of heavy weights, purportedly to support, stabilize and thereby attenuate the load on the spine. The purpose of this study was to examine the effects of a standard weightlifting belt in attenuating spinal shrinkage. Eight male subjects with a mean age of 24.8 years performed two sequences of circuit weight-training, one without a belt and on a separate occasion with a belt. The circuit training regimen consisted of six common weight-training exercises. These were performed in three sets of ten with a change of exercise after each set of ten repetitions. A stadiometer sensitive to within 0.01 mm was used to record alterations in stature. Measurements of stature were taken before and after completion of the circuit. The absolute visual analogue scale (AVAS) was used to measure the discomfort and pain intensity resulting from each of the two conditions. The circuit weight-training caused stature losses of 3.59mm without the belt and 2.87 mm with the belt (p › 0.05). The subjects complained of significantly less discomfort when the belt was worn (p < 0.05).
The degree of shrinkage was significantly correlated (r = 0.752, p < 0.05) with perceived discomfort but only when the belt was not worn. These results suggest the potential benefits of wearing a weightlifting belt and support the hypothesis that the belt can help in stabilizing the trunk.
Cassorla, F.; Mericq, V.; Eggers, M.; Avila, A.; Garcia, C.; Fuentes, A.; Rose, S. R.; Cutler, G. B., Jr. (1997) Effects of luteinizing hormone-releasing hormone analog-induced pubertal delay in growth hormone (GH)–deficient children treated with GH: preliminary results. J Clin Endocrinol Metabolism. 82, 12, 3989-3992.
Abstract: To study the effect of delaying epiphyseal fusion on the growth of GH-deficient children, we studied 14 pubertal, treatment naive, GH-deficient patients (6 girls and 8 boys) in a prospective, randomized, placebo-controlled trial. Chronological age was 14.5 ± 0.5 yr, and bone age was 11.6 ± 0.3 yr (mean ± SEM) at the beginning of the study. Patients were assigned randomly to receive GH and LH-releasing hormone (LHRH) analog (n = 8) or GH and placebo (n = 6) during 3 yr, with planned continuation of GH treatment until epiphyseal fusion. Patients were measured with a stadiometer and had serum LHRH tests, serum testosterone (boys), serum estradiol (girls), and bone age performed every 6 months.
Patients treated with GH and LHRH analog showed a clear suppression of their pituitary-gonadal axis and a marked delay in bone age progression. We observed a greater gain in height prediction in these patients than in the patients treated with GH and placebo after 3 yr of treatment (mean ± SEM, 14.0 ± 1.6 vs. 8.0 ± 2.4 cm; P 0.05). These preliminary findings suggest that delaying epiphyseal fusion with LHRH analog in pubertal GH-deficient children treated with GH increases height prediction and may increase final height compared to treatment with GH alone.
Dean, H. J.; Schentag, C. T.; Winter, J. S. (1990) Predictive value of short-term growth using knemometry in a large population of healthy children. Acta Paediatrics Scand. 79, 1, 57-63.
Abstract: We have analyzed the lower leg growth using a knemometer and the height growth using a stadiometer of 90 healthy children aged 3-16 years, for one year. The intra- and inter-individual monthly lower leg growth varied up to 4-fold, which was not accounted for by age or sex. The correlation between short term and annual lower leg growth rates increased with longer observation periods. There was no month-to-month consistency in the ratio of lower leg growth and height growth. There was no correlation between 1 month lower leg growth and annual height growth. The correlation increased with time. The 6-month observation interval was the interval with the highest predictive value for annual lower leg growth (R2 = 0.727) and annual height growth (R2 = 0.732). We conclude that growth of different parts of the skeleton and variable interval growth rates limits the ability of knemometry to predict long term growth.
Dennison, B. A.; Rockwell, H. L.; Baker, S. L. (1997) Excess fruit juice consumption by preschool-aged children is associated with short stature and obesity [see comments] [published erratum appears in Pediatrics 1997 Oct;100(4):733]. Pediatrics. 99, 1, 15-22.
Background: In a referral population of young children, excessive fruit juice consumption has been reported to be a contributing factor in nonorganic failure to thrive.
Objective: To evaluate, in a population-based sample of healthy children, fruit juice consumption and its effects on growth parameters during early childhood.
Design: Cross-sectional study. Setting: General primary care health center in upstate New York. Participants: One hundred sixteen 2-year-old children and one hundred seven 5-year-old children, who were scheduled for a nonacute visit, and their primary care taker/parent were recruited over a 2-year period.
Measurements: For 168 children (ninety-four 2-year-old children and seventy-four 5-year-old children), mean dietary intake was calculated from 7 days of written dietary records, entered, and analyzed using the Minnesota Nutrition Data System. Height was measured using a Harpenden Stadiometer. Weight was measured using a standard balance beam scale.
Results: The 2-year-old and 5-year-old children consumed, on average, 5.9 and 5.0 fl oz/day of fruit juice and 9.8 and 11.0 fl oz/day of milk, respectively. Nineteen children (11%) consumed › or = 12 fl oz/day of juice. Forty-two percent of children consuming › or = 12 fl oz/day of juice had short stature (height less than 20th sex-specific percentile for age) vs. 14% of children drinking less than 12 fl oz/day of juice. Obesity was more common among children drinking › or = 12 fl oz/day of juice compared with those drinking less juice: 53% vs. 32% had a body mass index › or = 75th age – and sex-specific percentile; 32% vs. 9% had a body mass index ± 90th age – and sex-specific percentile; and 32% vs. 5% had a ponderal index ± 90th age-specific percentile. After adjustment for maternal height, child age, child sex, and child age-sex interaction, children consuming ± 12 fl oz/day of juice, compared with those drinking less than 12 fl oz/day of juice, were shorter (86.5 vs. 89.3 cm and 106.5 vs. 111.2 cm for the 2-year-old and 5-year-old children, respectively) and more overweight (body mass index = 17.2 vs. 16.3 kg/m2 and ponderal index = 18.4 vs. 16.8 kg/m3).
Conclusions: Consumption of ± 12 fl oz/day of fruit juice by young children was associated with short stature and with obesity. Parents and care takers should limit young children’s consumption of fruit juice to less than 12 fl oz/day.
Devocht, J. W.; Pope, M. H.; Magnusson, M.; Spratt, K. F. (2000) Biomechanic evaluation of the Rola Stretcher as a passive distraction device. J Manipulative Physiological Therapy 23, 4, 252-257.
Introduction: Many devices have been marketed claiming to increase the mobility of the articulations of the spine with active or passive distraction. In this study, the Rola Stretcher (Unique Relief, Inc, Davenport, Iowa) and an earlier version, the True Back II (True Back, Inc, Clearwater, Fla), were evaluated to see if they have a measurable biomechanic effect on the spine.
Methods: Two studies were conducted, each with 6 male participants and 6 female participants, using a stadiometer to accurately measure a person’s sitting height. The increase in sitting height after using the True Back II or Rola Stretcher for 10 minutes was compared with that after lying supine for 10 minutes. A third intervention, a firm foam block cut to the same size and shape as the True Back II, was also used in this study.
Results: The Rola Stretcher had a significantly greater lengthening effect on the spine compared with supine rest (p < .005). The True Back II had a similar but lesser effect (p < .0509). Women demonstrated a greater height gain than men.
Conclusion: The True Back II and the Rola Stretcher in particular appear to lengthen the spine after a single use of 10 minutes. The observed discrepancy between the effects in men and women may be an experimental artifact occurring as a result of less effective resetting of the posturing mechanisms in men compared with women. A trend showed the Rola Stretcher to be more effective than the foam block.
Dowzer, C. N.; Reilly, T.; Cable, N. T. (1998) Effects of deep and shallow water running on spinal shrinkage. British J Sports Medicine 32, 1, 44-48.
Objectives: Running in water has the potential to decrease the compressive forces on the spine as the body is supported. The aim of the study was to determine the magnitude of this loss in stature compared with running on land. Methods: Fourteen runners completed three 30 minute runs on separate days in deep water, shallow water, and on a motor driven treadmill. During the three conditions, runners exercised at 80% of their exercise mode specific peak oxygen consumption. Subjects rested in the Fowler position for 20 minutes before and after exercise. Measurements of changes in stature were taken before resting, before running, after 15 minutes of running, after 30 minutes of running, and after the post-exercise rest in the Fowler position. Changes in stature were recorded using a stadiometer accurate to 0.01 mm.
Results: Loss of stature values were 4.59 (1.48), 5.51 (2.18), and 2.92 (1.7) mm (means (SD) for running on the treadmill, and in shallow and deep water respectively. Running in deep water caused significantly lower creep than in the other trials (p0.05), with no difference between the shallow water and treadmill conditions. Loss of stature was greater in the first half of the run for all conditions (p0.05). Ratings of perceived exertion did not differ between the three exercise conditions.
Conclusion: Results support the use of deep water running for decreasing the compressive load on the spine.
Eklund, J. (1984) Industrial Seating and Spinal Loading. Thesis submitted to the University of Nottingham, Dept. Production Engineering and Production Management. Nottingham, U.K.
Ensrud, K. E.; Black, D. M.; Harris, F.; Ettinger, B.; Cummings, S. R. (1997) Correlates of kyphosis in older women. The Fracture Intervention Trial Research Group. J Am Geriatr Society. 45, 6, 682-687.
Objective: To determine the association between kyphosis (degree of forward curvature of the thoracic spine) and measures of spinal osteoporosis (height loss and vertebral fractures) and chronic back pain and disability in older women. DESIGN: A cross-sectional study. SETTING: Eleven clinical centers in the United States.
Participants: A total of 6439 community-dwelling osteoporotic women aged 55-80 enrolled in the Fracture Intervention Trial (FIT), a multicenter clinical trial of alendronate. Measurements: Thoracic curvature was measured at baseline using a Debreuner Kyphometer. Height loss was determined by subtracting current height measured with a Harpenden stadiometer from self-reported height at age 25. Vertebral fractures were defined by morphometry and semiquantitative reading of lateral thoracic and lumbar spine radiographs, and chronic back pain and back-related disability were assessed by questionnaire.
Results: After adjustment for age, a 15° increase in kyphosis was associated with losing more than 4 cm of height (OR, 1.88; 95% CI, 1.79-2.03) and having a vertebral fracture (OR, 1.57; 95% CI, 1.46-1.69). Kyphosis was more strongly related to thoracic fractures than to lumbar fractures, and kyphosis was most prominent in women with multiple thoracic wedge fractures. Kyphosis was also associated with upper back pain (OR per 15° increase, 1.62; 95% CI 1.47-1.79) and middle back pain (OR per 15° increase, 1.24; 95% CI 1.12-1.36), but it was not related to lower back pain (OR per 15° increase, 0.98; 95% CI 0.90-1.05). Women with greater degrees of kyphosis were only slightly more likely to report back-related disability (OR per 15° increase, 1.18; 95% CI 1.03-1.35) and poorer health status (OR per 15° increase, 1.19; 95% CI 1.03 – 1.37).
Conclusions: Older women with greater degrees of kyphosis are likely to have other manifestations of spinal osteoporosis such as height loss and thoracic fractures and to suffer chronic upper and middle back pain. Measurement of kyphosis may be useful in assessing the severity of spinal osteoporosis.
Fowler, N. E.; Lees, A.; Reilly, T. (1994) Spinal shrinkage in unloaded and loaded drop-jumping. Ergonomics 37, 1, 133-139.
Abstract: Plyometric activities, engaging the muscle in a stretch-shortening cycle, are widely used in athletic training. One such plyometric exercise is drop-jumping, where the athlete drops from a raised platform and immediately on landing performs a maximal vertical jump. These actions are also performed with the athlete externally loaded by the addition of weights to provide greater resistance. Exercises which involve repeated impacts have been shown to give rise to a loss of stature (shrinkage) which can be measured by means of a sensitive stadiometer.
This study examined the shrinkage induced by unloaded and loaded drop-jumping from a height of 26 cm. Eight male subjects, aged 20-24 years, performed the test protocol three times, at the same time of day on each occasion. Fifty drop-jumps from a height of 26 cm were performed with no additional load and with a load of 8.5 kg carried in a weighted vest. The third condition was a standing trial where the subject stood for 10 min (the time taken to perform the jumps) wearing the weighted vest. Stature was measured before exercise, immediately after exercise and after a 20 min standing recovery. On a separate occasion the regimen was performed and the vertical reaction force was measured using a Kistler force platform.
The mean change in stature for the two jump conditions showed shrinkages of 0.62 (± 0.43) mm for unloaded and 2.14 (± 1.56) mm for the loaded (p 0.05). The variance in shrinkage was greater in the loaded case compared to the unloaded condition (p 0.05) indicating a wider range of jumping strategies.
Fowler, N. E.; Lees, A.; Reilly, T. (1997) Changes in stature following plyometric drop-jump and pendulum exercises. Ergonomics 40, 12, 1279-1286.
Abstract: The aim of this study was to compare the changes in stature following the performance of plyometric exercises using drop-jumps and a pendulum swing. Eight male participants aged 21.7 ± 1.8 years with experience of plyometric training gave their informed consent to act as participants. Participants undertook two exercise regimens and a 15-min standing test in a random order. The exercises entailed the performance of 50 drop-jumps from a height of 0.28 m or 50 pendulum rebounds. Participants were instructed to perform maximal jumps or rebounds using a bounce style. Measurements of stature were performed after a 20-min period of standing (pre-exercise), 2-min after exercise (post-exercise) and after a 20-min standing recovery (recovery). Back pain and muscle soreness were assessed using an analogue-visual scale, at each of the above times and also 24 and 36 h after the test. Peak torque during isokinetic knee extension at 1.04 rads-1 was measured immediately before and after the exercise bouts, to assess the degree of muscular fatigue. Ground/wall reaction force data were recorded using a Kistler force platform mounted in the floor for drop-jumps and vertically on the rebound wall for pendulum exercises.
Drop-jumps resulted in the greatest (p < 0.05) change in stature (-2.71 ± 0.8 mm), compared to pendulum exercises (-1.77 ± 0.7 mm) and standing (-0.39 ± 0.2 mm). Both exercise regimens resulted in a significant (p < 0.01) decrease in stature when compared to the standing condition. Drop-jumps resulted in significantly greater peak impact forces (p < 0.05) than pendulum exercises (drop-jumps = 3.2 ± 0.5 x body weight, pendulum = 2.6 ± 0.5 x body weight). The two exercise conditions both invoked a small degree of muscle soreness but there were no significant differences between conditions.
Both exercise regimens resulted in a non-significant decrease in peak torque indicating a similar degree of muscular fatigue. Based on the lower shrinkage resulted and lower peak forces, it can be concluded that pendulum exercises pose a lower injury potential to the lower back than drop-jumps performed from a height of 28 cm.
Garbutt, G.; Boocock, M. G.; Reilly, T.; Troup, J. D. (1990) Running speed and spinal shrinkage in runners with and without low back pain. Med Sci Sports Exercises 22, 6, 769-772.
Abstract: Decreases in stature (shrinkage) are used to indicate exercise induced spinal loading. This study examined the effect of three running speeds on two groups of runners, one with chronic low back pain. The two groups of seven male marathon runners ran at 70%, 85%, and 100% of their marathon race pace for 30 min on separate occasions. Before and after exercise the subjects were seated for 20 min with the lumbar spine supported. Stature was measured before pre-exercise sitting, before running, after 15 min of running, after 30 min of running, and after post-exercise sitting. A stadiometer accurate to within 0.5 mm was used to record changes in stature.
Results showed no differences in response to the three running regimens between the groups (P greater than 0.05). Shrinkage was greater during the first 15 min, being 3.26 (± 2.78) mm compared with 2.12 (± 1.61) mm for the second 15 min of the run (P < 0.05). The faster the running speed the greater the resultant shrinkage. The 70%, 85%, and 100% conditions caused 3.37 (± 2.38), 5.10 (± 1.90), and 7.69 (± 3.69) mm of shrinkage, respectively (P < 0.005). These results suggest that low back pain is independent of the shrinkage induced by running. Further research is required to determine the effect of longer duration runs on spinal shrinkage.
Garbutt, G.; Boocock, M. G.; Reilly, T.; Troup, J. D. (1994) Physiological and spinal responses to circuit weight-training. Ergonomics 37, 1, 117-125.
Abstract: Physiological, perceptual and physical responses to a typical circuit weight-training (CWT) regimen were recorded in two studies. The aims were to assess the intensity of exercise during CWT; and to determine whether physical responses as evaluated by spinal shrinkage were related to physiological and perceptual responses to CWT.
In the first study (n = 10) heart rate (HR), oxygen consumption (VO2), ventilation (VE), blood lactate (La) and perceived exertion (RPE) were measured in response to CWT. Mean (± SD) time to complete three circuits of CWT was 17.8 (± 1.4) min. The HR max, VO2 max and peak La, measured first during an incremental treadmill test, were 195 (± 13) beats.min-1, 59.7 (± 4.8) ml.kg-1.min-1 and 14.3 (± 3.5) mM respectively. Mean HR and VO2 during CWT were 69% and 50% of the respective maximal values. The HR-VO2 ratio observed on the treadmill was elevated during CWT, with VO2 being lowered relative to HR. Mean VE and La values were 52.7 (± 14.5) l.min-1 and 6.9 (± 3.6) mM. The effect of the same CWT regimen on spinal loading as indicated by change in stature (shrinkage) was investigated in a second study (n = 8). The mean (± SD) time taken to complete the circuit was 17.4 (± 1.3) min. Mean shrinkage due to CWT (2.5 ± 1.5 mm) was unrelated to the time taken to complete the circuits, to HR, RPE or to low back pain ratings (p › 0.05).
Helander, M.G.; Quance, L.A., (1990) Effect of Work-Rest Schedules on Spinal Shrinkage in the Sedentary Worker. Applied Ergonomics. 21 18, 4, 279-284.
Abstract: The relationship between duration and frequency of rest intervals and spinal shrinkage was investigated. The objective was to determine whether the amount of spinal shrinkage can be significantly reduced by rest breaks during which the individual is either walking or standing rather than sitting. Seven subjects were studied during 4-h sessions for four consecutive days. During each session the subject sat and typed for a total of 3 h 20 min. Forty minutes of rest breaks were dispersed throughout the 4-h period. One condition was administered during each day with either eight breaks of 5 min, four breaks of 10 min, two breaks of 20 min or a single break of 40 min at the end of the work session. Using a stadiometer, changes in stature were measured with an accuracy of about 0.2 mm. Measurements were taken at the beginning of each work period and before and after each rest break.
"For the conditions with rest breaks of 20 or 40 min, there was significantly less shrinkage at the end of the 4-h work session".
Hermanussen, M.; Geiger-Benoit, K. (1995) No evidence for saltation in human growth. Ann Human Biology 22, 4, 341-345.
Abstract: Recently a new model of human growth has been presented suggesting alternating periods of stasis (mean 24.5 days in the case of weekly measurements) and short saltatory increments of body height between 5 and 25 mm that had been detected between subsequent weekly or semi-weekly height measurements, i.e. within single weekly or semi-weekly intervals. The present study was undertaken to re-investigate and, if possible, to confirm this model. Body height was measured by stadiometer in 32 healthy pre-school and school age children, at weekly or semi-weekly intervals for periods between 4 and 8 months.
Though the authors found evidence for an accumulation of weekly and semi-weekly height differences that suggested periods of no growth (stasis), there was no evidence for saltatory increments either in the 850 weekly or in the 746 semi-weekly body height differences.
Hoe, A.; Atha, J.; Murray-Leslie, C. (1994) Stature loss from sustained gentle body loading. Ann Human Biology 21, 2, 171-178.
Abstract: The effects of low levels of loading on spinal creep have been investigated in nine young men aged between 19 and 24 years. The stimulus for the project was an interest in the potential use of stadiometry in evaluating selected classes of patients with spinal disorders. Underlying the experiment was the view that if gentle spinal loadings cannot be differentiated sensitively in normal young adults then the feasibility of using stadiometric measurements to identify patients with decreased lability is questionable. Subjects were measured on a precision stadiometer before and after 25 minutes of free standing and quiet walking, and the resultant stature losses compared with the more substantial losses observed following steady running. All measurements were made following the same pre-session routine, at exactly the same time on three separate mornings.
It was observed that while no appreciable stature loss followed standing (mean = 0.01 mm; SE = 0.65 mm; p > 0.05) even quiet walking had a measurable and statistically significant effect (mean = 1.82 mm; SE = 0.49 mm; p 0.01). Compared with these, steady running produced almost 2 1/2 times as great a loss (mean = 4.32 mm; SE = 0.83 mm; p 0.01).
It is concluded: (a) that erect standing provides a useful neutral baseline from which the changes associated with spinal loading and unloading may be measured; (b) that the effects of even gentle spinal loadings may be differentiated sensitively by precision stadiometry; and (c) that easy walking is one such gentle stimulus with detectable effects in normal young men.
Jafry, T.; Haslegrave, C.M. (1992) The Development of a Precision Seated Stadiometer for Measuring the Effects of Vibration on the Human Spine. Lovesey, E.J.: Contemporary Ergonomics 1992. London, Taylor & Francis. 79-84.
Abstract: Precision standing stadiometers have been used to measure body height change as an indicator of load imposed on the spine for both static and dynamic loading conditions. However, problems have been found in using this apparatus for measuring the effects of a seated task and this has led to the development of a seated stadiometer. This study compared measurements obtained with the two types of stadiometer, recording the effects of sitting with and without vibration.
The seated stadiometer results indicated that subjects had reduced in stature for both conditions while the standing stadiometer recorded expansion for both conditions. This contradiction in results has given rise to concern when considering the use of standing stadiometers for measuring spinal loading in seated tasks. The results also suggested that vibration (4Hz 1ms -2 peak acceleration) had no significant effect on spinal loading, hardware design for experimentation, instrument recording, Physiological and psycho-physiological recording.
Kanlayanaphotporn, R.; Trott, P.; Williams, M.; Fulton, I. (2001) Contribution of soft tissue deformation below the sacrum to the measurement of total height loss in sitting. Ergonomics. 44, 7, 685-695.
Abstract: This study investigated the contribution of soft tissue deformation below the sacrum (S) and vertical spinal creep to total height loss (THL) measured in sitting. Eight asymptomatic subjects (four males, four females) aged between 21 and 51 years were measured. Simultaneous measurement of THL and S were commenced after the subjects had been sitting for 5 min. THL was recorded while subjects were positioned in a seated stadiometer, which controlled their spinal posture. S was measured by placing an ultrasound transducer at the level of the top of the subject’s sacrum. Over 25 min of sitting with loaded and unloaded interventions applied to their spine, different response characteristics between S and THL were noted.
This study demonstrated that soft tissues below the sacrum could contribute up to 30% on average of total height loss. This suggests that researchers should take into account the soft tissue deformation outside the spine when studying vertical creep in sitting.
Kuczmarski, M. F.; Kuczmarski, R. J.; Najjar, M. (2001) Effects of age on validity of self-reported height, weight, and body mass index: findings from the Third National Health and Nutrition Examination Survey, 1988-1994. J Am Diet Assoc. 101, 1, 28-34; quiz 35-26.
Objective: To compare self-reported to measured heights and weights of adults examined in the Third National Health and Nutrition Examination Survey (NHANES III), and to determine to what extent body mass index (BMI) calculated from self-reported heights and weights affects estimates of overweight prevalence compared with BMI calculated from measured values.
Design: A complex sample design was used in NHANES III to obtain a nationally representative sample of the US civilian, non-institutionalized population. During household interviews, survey respondents were asked their height and weight. Trained health technicians subsequently measured height and weight using standardized procedures and equipment.
Subjects: The analytical sample consisted of 7,772 men and 8,801 women 20 years old and older. Statistical analyses performed: Only persons with measured and self-reported heights and weights were included in the analysis, and statistical sampling weights were applied. t Tests, Pearson product moment correlation coefficients, sensitivity, and specificity analyses were used to determine the validity of self-reported measurements and prevalence estimates of overweight, defined as BMI of 25 or greater.
Results: Age is an important factor in classifying weight, height, BMI, and overweight from self-reports. Statistically significant differences were found for the mean error (measured-self-reported values) for height and BMI that were notably larger for older age groups. For example, the mean error for height ranged from 2.92 to 4.50 cm for women and from 3.06 to 4.29 cm for men, 70 years and older. Despite the high correlation between measured and self-reported data, the prevalence of overweight calculated from measured values was higher than that calculated from self-reported values among older adults. When calculated with self-reported height, BMI was one unit lower than when calculated from measured height for persons ± 70 years. Specificity was high but sensitivity decreased with increasing age cohorts. Regression equations are provided to determine actual height from self-reported values for older adults.
Conclusion/Applications: Self-reported heights and weights can be used with younger adults, but they have limitations for older adults, ages ± 60 years. In research studies and in clinical settings involving older adults, failure to measure height and weight can result in subsequent misclassification of overweight status. Therefore, registered dietitians are encouraged to obtain a measured weight and height using a calibrated scale and stadiometer.
Leatt, P.; Reilly, T.; Troup, J. G. (1986) Spinal loading during circuit weight-training and running. British J Sports Medicine 20, 3, 119-124.
Abstract: Spinal shrinkage was used as an indicant of loading on the spine in circuit weight-training and running regimes. The loss of stature during two sets of a circuit of weight-training (n = 10), a 6 km run by novices (n = 9) and a 25 km run by trained runners (n = 7) was assessed in male subjects.
Shrinkage was not significantly different between the weight-training regime and the 6 km run by novices, mean losses being 5.4 and 3.25 mm respectively.The rate of height loss in the experienced runners was 2.35 mm over 6 km run at 12.2 km.h-1, representing 0.4 mm.km-1 over the 6 km run, this shrinkage rate being continued over the last 19 km run at 14.7 km.h-1. The loss of height could not be predicted from a set of covariates. The magnitude of the circadian variation, mean 14.4 mm, exceeded the change in height during the 25 km run. The diurnal variation conformed to a cosine function, though a better fit was obtained with a power function equation. A marked diurnal pattern was also observed in lumbar extension. Though reversal of spinal shrinkage was observed during a night’s sleep, no significant recovery occurred during a 20 min resting period immediately following the exercise regimes. These results have implications for the warm-up and timing of exercise regimes that impose significant loading on the spine.
Leivseth, G.; Drerup, B., (1997) Spinal Shrinkage during Work in a Sitting Posture Compared to Work in a Standing Posture. Clinical Biomechanics. 12 34, 7-8, 409-418.
Abstract: The objective was to measure the possible differences in shrinkage of the thoracolumbar spine in subjects working in a sitting and a standing posture for 6.5 h at work, in a realistic work environment. The isolated shrinkage of the thoracic and the lumbar spine was also examined. This study presents a new protocol to measure shrinkage of the thoracic and lumbar spine separately.
Controversies still exist with regard to the load on the spine in a sitting compared to a standing position. Some report that shrinkage is greatest in the sitting position while others report the reverse. However, nothing is known about the height reduction of thoracic and the lumbar spine during loading for 6.5 h in a real work environment. Therefore, the behavior of the thoracic and the lumbar spine under practical condition has to be investigated.
A stadiometer with a measurement error of 0.51 mm was used to measure changes in spinal height during work. To exclude first-time behavior of the spine, a pre-test lasting 50 min was undertaken. The mean of the last three measurements was used as the reference height. During work, height measurements of the spine were performed every 20 min. To separate the behavior of the thoracic and the lumbar spine, two benchmarks were placed at the vertebrae prominens and at the thoracic-lumbar junction. Shrinkage of the spine was investigated within three different cohorts: (i) work in a sitting posture for 6.5 h; (ii) relaxed sitting for 2 h vs. work for 2 h in a sitting position and (iii) work in a standing position for 6.5 h.
Relaxed sitting leads to a gain in stature compared to work in a sitting position for 2 h. The major gain in stature occurred in the lumbar spine. Comparison of cohort (iii) working in a standing position with cohort (i) working in a sitting position shows that the shrinkage of the spine is greatest when work is performed in a standing posture. The major differences were found in the shrinkage of the lumbar spine, e.g. shrinkage of the lumbar spine in the standing cohort (iii) was 4.16 mm compared to 1.73 mm in the sitting cohort (i). There is a gain in stature during relaxed sitting compared to work in a sitting posture. The load on the spine is greatest when work in a standing position is performed. The greater shrinkage of the lumbar spine during work in a standing position compared to sitting postures is probably due to: (i) differences in lumbar lordosis and (ii) the effect of bending and torsion while handling the work materials.
Lueder, R.; Corlett, E.N.; Danielson, C.; Greenstein, G.C.; Hsieh, J.; Phillips, R.; DesignWorks/USA (1994) Does It Matter That People Are Shaped Differently, Yet Backrests Are Built the Same? Lueder, R. and Noro, K.: Hard Facts about Soft Machines: The Ergonomics of Seating, London, Taylor & Francis. 205-217.
Abstract: A sample of these subjects sat for 60 minute trials, and their stature was measured three times; pre-trial, after 30 minutes, and after 60 minutes. The data from these subjects indicated that significant differences existed in stature after the first and second half hour, and these differences were both in magnitude as well as in direction of change. Such findings are surprising, and its reason can not be immediately surmised. If these findings are reproduced in other studies, they warrant attention; however, this analysis was unfortunately beyond the scope of the present study.
Findings: Intra-examiner correlation coefficients of lumbar characteristics of the upright, flexed, and extended seated positions were calculated between the flexicurve measures. Correlation coefficients were .96 during flexion, .80 in extension, and .95 for the upright ("neutral") positions. (p < .05).
Analysis of Variance indicated that both the lumbar seat depth or back rest angle did not significantly affect stature (measured from stadiometer), although the effect of seat lumbar depth reached p=.11. Measures of lumbar lordosis and range of motion were not able to predict either subjective ratings of discomfort or changes of stature (spinal loading with the stadiometer) In general, the 3 cm lumbar support depth was rated as the most comfortable for all subjects, at both back rest angles.
Magnusson, M. L.; Aleksiev, A. R.; Spratt, K. F.; Lakes, R. S.; Pope, M. H. (1996) Hyperextension and spine height changes. Spine. 21, 22, 2670-2675.
Study Design: The effect on spine height changes from different combinations of time and angle of static prone hyperextension, and one intervention of dynamic hyperextension was explored.
Objectives: To explore whether controlled hyperextension would cause a height increase with greater duration than previously shown, and to find an optimal combination of hyperextension angle and duration of the intervention.
Methods: Ten subjects were exposed to hyperextension in the prone position for different time periods and with different amounts of hyperextension. The effect was measured using the stadiometer for measurement of spine height changes.
Results: The study showed that time was the most important variable, and also that for a given time, there was an increased recovery with increased angle.
Conclusions: The results indicate that hyperextension can be a beneficial maneuver to unload temporarily the spine after loading and to rehydrate the discs, providing enough time is given for the procedure. The optimal time and angle combination was 20° for 20 minutes because this intervention resulted in the largest recovery that lasted for a relatively long period of time.
Magnusson, M. L.; Pope, M. H.; Hansson, T. (1995) Does hyperextension have an unloading effect on the intervertebral disc? Scand J Rehabilitation Medicine. 27, 1, 5-9.
Abstract: A stadiometer (a device to measure the overall height of a subject) was used to determine the effect of hyperextension in rehydration of the intervertebral disc. Hyperextension for 20 minutes in a prone posture was compared with the prone posture alone for 20 minutes. The stadiometer measurement was made after the subject was exposed to 10 kg of loading applied to the shoulders for five minutes and after each of the recovery postures.
It was found that hyperextension gave a significantly increased height recovery compared with the prone posture.
McGill, S. M.; van Wijk, M. J.; Axler, C. T.; Gletsu, M. (1996) Studies of spinal shrinkage to evaluate low-back loading in the workplace. Ergonomics 39, 1, 92-102.
Abstract: Measurement of spinal shrinkage (stadiometry) has been suggested to be a convenient measure of low-back load in workplace settings. This report documents three separate experiments that collectively form a central theme: Is the measurement of spinal shrinkage a suitable assessment technique to quantify the cumulative effect of loading on the low back given the many sources for variability in the signal? A stadiometer was fabricated to measure both sitting and standing height.
The first experiment was to compare sitting with standing stature changes over time in an attempt to locate the major site of shrinkage. There were no statistically significant differences in stature change found between either the sitting or standing posture for any condition suggesting that nearly all height changes occur in the spine.
The second experiment compared the cumulative effects from static load holding to dynamic load lifting. Some subjects experienced more shrinkage in the static task while others experienced more in the dynamic task.
In the third experiment, subjects performed work-rest cycles consisting of periods of sitting and lifting, and repeated over two days, to examine the recovery phenomenon.
No specific pattern emerged owing to unpredictable subject variability. The first general observation obtained from the results of all three experiments is that the response of subjects to a wide array of activities appears to be variable both within each subject and over repeated exposures to identical conditions on different days. While subject variability (and perhaps biological variability) is a liability, it may be feasible to develop load time integrals for load exposure in the future, since the asset of the spinal shrinkage approach appears to be that it is one of the few available techniques to assess cumulative loading for both isometric postures, prolonged sitting, repeated tasks and responds to the positive adaptive changes that occur from periods of rest. However, it would appear that more quantification of the relationships that modulate spinal shrinkage are required to account for the variance in stature measurements.
Michel, D. P.; Helander, M. G. (1994) Effects of two types of chairs on stature change and comfort for individuals with healthy and herniated discs. Ergonomics 37, 7, 1231-1244.
Abstract: The objective of this study was to determine if stature change and perceived comfort are significantly different for individuals with either healthy or herniated discs when seated in a conventional chair or a sit-stand chair. Sixteen subjects were studied (5 young/healthy, 6 old/healthy, 5 old/herniated). Subjects performed a search task on a computer screen during two 2 h sessions for two consecutive days, with a different chair each day. Changes in stature were measured with a stadiometer. General comfort and body parts discomfort rating scales were administered every 30 min.
The main findings were: (1) for all subjects, the sit-stand chair produces less height loss than the conventional chair; and (2) for both chairs, subjects with herniated discs lost more height than subjects with healthy discs. A positive correlation was observed for height loss and age with the sit-stand chair. Subjects with herniated discs felt relatively more uncomfortable in the conventional chair and more comfortable in the sit-stand chair compared to subjects with healthy discs. Both old healthy and young healthy subjects felt more comfortable in the conventional chair in comparison to the sit-stand chair. But, old healthy subjects had a relatively greater perception of comfort in the conventional chair compared with the younger subjects.
Reilly, T.; Seaton, A. (1990) Physiological strain unique to field hockey. J Sports Med Phys Fitness. 30, 2, 142-146.
Abstract: Unique requirements of field hockey include dribbling the ball and moving quickly in a semi-crouched posture. First, the net physiological strain due to dribbling was examined. Seven male hockey players completed a 5 min run on the treadmill at 8 km h-1 and 10 km h-1: subjects also ran at these speeds whilst dribbling a hockey ball. Dribbling increased energy expenditure by 15-16 kJ min-1 above that observed in normal running. Heart rates and perceived exertion were also increased. The posture in dribbling is likely to cause back ache among players: 53% of respondents (n = 81) reported experience of lower back pain. Finally, the shrinkage of spinal length during dribbling was examined. Subjects (n = 7) ran for 7 min on the treadmill whilst dribbling a ball. Shrinkage occurred at a rate of 0.4 mm min-1, which is greater than previously reported for other activities. The peculiar postural requirements of field hockey seem to cause physiological strain and spinal loading in excess of orthodox motion.
Reilly, T.; Chana, D. (1994) Spinal shrinkage in fast bowling. Ergonomics 37, 1, 127-132.
Abstract: The load on the spine during physical activities may be reflected in decreases in stature, referred to as shrinkage. Spinal shrinkage reflects the creep behaviour of the intervertebral discs and vertebral end-plate compression when loaded. This study was concerned with shrinkage induced during practices corresponding to fast bowling in cricket, an activity associated with risk of back injury. Eight cricketers (aged 19-24 years), all free of back pain, acted as subjects. They were first trained for measurement on the stadiometer until 10 consecutive recordings of stature with SD 0.05).
Rodacki, C. L.; Fowler, N. E.; Rodacki, A. L.; Birch, K. (2001) Technical note: repeatability of measurement in determining stature in sitting and standing postures. Ergonomics 44, 12, 1076-1085.
Abstract: The aim of this study was to determine the effect of sitting and standing postures on the repeatability of a stadiometer designed to detect small variations in spinal length. Two groups of ten healthy subjects, with no previous or known history of back problems, participated in this study. One group was measured in the standing posture, while the other group was measured in a sitting posture. All subjects gave informed consent to participate in this study. Subjects had a set of landmarks defining the spinal contour marked on their backs and then stood in the stadiometer for three series of ten measurements to be performed. At the end of each measurement, the subjects were requested to move away from and then be repositioned in the stadiometer. Subjects improved the repeatability across the measurement series.
At the end of the second measurement series, all subjects presented mean standard deviations of 0.43 ± 0.08 mm (range 0.30-0.50 mm) in the standing posture. In the sitting posture, deviations of less than 0.05 mm were obtained only at the end of the third measurement series (0.48 ± 0.08 mm; range 0.34-0.62 mm), suggesting that this posture required three measurement series before repeatable measurements could be assured rather than two in the standing posture.
Sandiford, P.; Cassel, J.; Melendez, D.; Coldham, C. (1994) The electronic stadiometer: an appropriate technology for height measurement in health surveys. Trop Doct. 24, 1, 24-25.
Seixas, N. S.; Sheppard, L. (1996) Maximizing accuracy and precision using individual and grouped exposure assessments. Scand J Work Environments Health. 22, 2, 94-101.
Objectives: Random errors in exposure data were explored to determine their effect on exposure-response relationships using individual, grouped, or combined (grouped and individual) exposure assessment methods.
Methods: Monte Carlo simulations were conducted by generating small "studies" of one hundred subjects divided into four exposure groups. Observed exposure data were generated for each individual using assumed inter- and intra individual variances and a lognormal distribution. The data were used to calculate the following three estimates of exposure: an individual mean, a group mean, and a hybrid estimate using the James-Stein shrinkage estimator. The exposure estimates were regressed on generated (continuous) "health outcomes," and the regression results were stored and analyzed.
Results: Random errors in exposure data resulted in attenuation of the exposure-response relationship when the individual estimates were used, especially when the within-subject variability was high. The attenuation was substantially controlled by the group mean estimate, however, at a cost of decreased precision. The hybrid estimator simultaneously Controlled both bias and imprecision in the observed exposure-response function.
Conclusions: While estimates of exposure based on individual means may result in attenuation of the exposure-response relationship, grouped estimates may control bias while decreasing precision. Combining individual and group estimates can simultaneously control both types of error. However, further research is required to determine how robust these findings are to different error structures, grouping strategies, exposure-response models, and exposure assessment methods.
Stalhammar, H. R.; Leskinen, T. P.; Rautanen, M. T.; Troup, J. D. (1992) Shrinkage and psychophysical load ratings in self-paced and force-paced lifting work and during recovery. Ergonomics 35, 1, 1-5.
Abstract: The purpose of this study was to investigate the effects of the load on the human spine during force-paced and self-paced lifting and subsequent rest. Five women and five men worked under self-paced and force-paced (4 lifts/min) conditions on two days lifting a box for 30 min. The weight of the box was determined by the rating of acceptable load (RAL) method. During the work the lift rate was observed, and subjects made rating of perceived exertion (RPE) in 5 min intervals. The stature was measured with a stature meter before and after the work period and during the following 30 min rest lying.
In self-paced work women had a higher lift rate than men (p < 0.05). In general, RPEs increased towards the end of the lifting period but RPEs did not differ between women and men or between self-paced and force-paced work. The mean shrinkage during the 30 min work was in self-paced work 5.1 ± 2.0 mm for women and 5.8 ± 1.2 mm for men, and in force-paced work 5.8 ± 2.3 mm and 6.8 ± 2.2 mm, respectively.
There were no significant differences in shrinkage at work between women and men nor between the two different pacing methods. During the 30 min rest recumbent the subjects regained almost the same amount of height as they had lost during lifting. The rapid shrinkage and recovery when loading and unloading suggest that a few minutes rest lying after heavy activities would be beneficial for the spine.
Stothart, J. P.; McGill, S. M. (2000) Stadiometry: on measurement technique to reduce variability in spine shrinkage measurement. Clinical Biomechanics (Bristol, Avon). 15, 7, 546-548.
Objective: To test the effect of two measurement techniques for repeated measures of spine height using stadiometry following five experimental activity conditions. Design. Six subjects were repeatedly measured while they stepped in and out of the stadiometer for each pair of measures and again on another day when they remained in place in the stadiometer for all 10 measures.
Results. There was much greater variability in height measures with the "in-out" method while the "in place" method demonstrated a steady shrinkage over the 3-3.5 min required to obtain the repeated measures.
Relevance: Contrary to popular practice, leaving a subject in the stadiometer during repeated measures includes the shrinkage that occurs over the 3-3.5 min of measurement when standing and reduces random variation due to posture change.
Tyrrell, A. R.; Reilly, T.; Troup, J. D. (1985) Circadian variation in stature and the effects of spinal loading. Spine. 10, 2, 161-164.
Abstract: Using a method comparable with that of Eklund and Corlett (1984) stature was measured with an accuracy of I mm in eight young adults. The mean circadian variation was 19.3 mm (1.1% of stature).
Fifty-four percent of the diurnal loss in stature occurred in the first hour after rising. Approximately 70% was regained during the first half of the night. With static shoulder loads (2.5-40 kg), increases in the rate of shrinkage with increasing weight were nonlinear. Repetitive lifting led to greater shrinkage than with equivalent static loading. Rest in Fowler’s position gave more rapid regains in stature than post-exercise recovery in standing positions. The technique is therefore suitable for assessment of the effects of manual work with both occupational and therapeutic applications.
van Deursen, D. L.; Goossens, R. H.; Evers, J. J.; van der Helm, F. C.; van Deursen, L. L. (2000) Length of the spine while sitting on a new concept for an office chair. Applied Ergonomics 31, 1, 95-98.
Abstract: Changes in spinal length were used to evaluate a new concept for an office chair. This so-called dynamic chair imparts passive forced motion to the seated subject. The passive forced motion is a rotary movement about an axis, perpendicular to the seat with amplitude of 0.6° and a frequency of 0.08 Hz. Change of stature is assumed to provide a measure for spinal load. Eight subjects were measured in two situations: static (without motion) and dynamic. In both situations the same office tasks were performed and the duration of the sitting period was 1 h. To allow for the normal shrinkage curve the starting time was the same on each of the measurement days.
The results indicated a significant difference: when sitting on the dynamic chair the average spinal length increased in comparison to the spinal length in the static chair, where average spinal length decreased. It was concluded that there is spinal distress relief due to the passive motion of the chair.
van Deursen, D. L.; Lengsfeld, M.; Snijders, C. J.; Evers, J. J.; Goossens, R. H. (2000) Mechanical effects of continuous passive motion on the lumbar spine in seating. J Biomechanics 33, 6, 695-699.
Abstract: The aim of this study was to develop a model which describes the mechanical spinal response to small alternating pelvic stimulation induced by an active rotational movement of a normal chair. The rotary continuous passive motion (RCPM) of the seat about a vertical axis of only 0.6° resulted in an increased in spinal length as opposed to the normal daily shrinkage, and back patients experienced pain relief. Passive and active exercises have been broadly applied for treating and healing spinal disorders. A rigid body package (ADAMS Android) was used to translate the stimulation of the ischial tuberosity in caudo-cranial handing-over visualization. The parameters of the model were set so that the values of the global stiffness and geometry of the intervertebral discs could be changed. In vivo validation of the model was based on force and moment measurements using an internal AO fixator. The predictions of the model concerning natural frequency (4.5Hz) in vertical direction and the axial torsion response on small pelvic torsion are comparable with experimental data.
van Dieen, J. H.; de Looze, M. P.; Hermans, V. (2001) Effects of dynamic office chairs on trunk kinematics, trunk extensor EMG and spinal shrinkage. Ergonomics 44, 7, 739-750.
Abstract: Seated work has been shown to constitute a risk factor for low-back pain. This is attributed to the prolonged and monotonous low-level mechanical load imposed by a seated posture. To evaluate the potential health effects with respect to the low back of office chairs with a movable seat and back rest, trunk kinematics, erector spinae EMG, spinal shrinkage and local discomfort were assessed in 10 subjects performing simulated office work. On three separate occasions subjects performed a 3 h task consisting of word processing, computer-aided design and reading. Three chairs were used, one with a fixed seat and back rest and two dynamic chairs, one with a seat and back rest movable in a fixed ratio with respect to each other, and one with a freely movable seat and back rest.
Spinal shrinkage measurements showed a larger stature gain when working on the two dynamic chairs as compared with working on the chair with fixed seat and back rest. Trunk kinematics and erector spinae EMG were strongly affected by the task performed but not by the chair type. The results imply that dynamic office chairs offer a potential advantage over fixed chairs, but the effects of the task on the indicators of trunk load investigated were more pronounced than the effects of the chair.
Wallace, P.; Reilly, T. (1993) Spinal and metabolic loading during simulations of golf play. J Sports Science 11, 6, 511-515.
Abstract: Changes in stature during physical activity reflect alterations in spinal column length that occur as a result of loading the spine. The shrinkage is associated with loss of intervertebral disc height. This study aimed to measure both the load on the spine during simulations of a round of golf and the physiological responses to carrying golf clubs. Fine measurement of stature was achieved using a computer-linked stadiometer inclined to 13°. Shrinkage was measured (n = 6) after performance regimens which mimicked (1) the ambulatory activity during golf play, (2) ambulation and skills employed in par performance and (3) ambulation and carriage of clubs.
Our observations indicate significant shrinkage associated with golf skills, mean shrinkage after nine holes being 2.53 mm compared to 1.78 mm in the walking condition. The highest shrinkage was observed when the player carried his clubs, the amount of stature loss being 4.76 mm over nine holes. The highest rates of shrinkage occurred over the first three holes. In a second experiment to further examine the effects of carrying the golf clubs, five of the subjects walked on a motor-driven treadmill at 5 km h-1 for 5 min. Carrying the clubs caused a 15% increase in VO2 and a 25% rise in VE compared to normal walking. Increases were found also in perceived exertion. The physical and physiological loadings associated with recreational golf were deemed to be light to moderate and do not denote undue strain in occasional practices.
Watt, V.; Pickering, M.; Wales, J. K. (1998) A comparison of ultrasonic and mechanical stadiometry. Archives Diseases Childhood. 78, 3, 269-270.
Abstract: Aim: To compare an ultrasonic height measuring device (Gulliver) with mechanical stadiometry and the classical "book and tape measure" method. Methods: Blinded duplicate measurements of height were made on each of 14 children by a pair of observers using a stadiometer (H) and Gulliver (G). Height was measured on a further 18 children by parents and an auxologist using Gulliver and the book and tape method (TM), and the results were compared with those obtained with a single stadiometry measurement. Finally, measurement of a rigid metal box was made on 10 occasions by the three methods.
Results: In the group of 14 children, the mean difference (range) in height (H minus G) was +2.8 cm (+0.5 to +4.55 cm), with H giving a systematically higher value in 276 of 280 individual measurements. In the group of 18 children, height by H was greater than by G or TM in 47 of 52 individual measurements. The mean (SD) height of the box by H (61.60 (0.07) cm) was greater than by G (60.96 (0.15) cm; p 0.05). G and TM produced three times less reliable estimations of height than H, but with a large difference in cost, and there was evidence of systematic under-recording of height by 0.5 cm with G.
Conclusions: Stadiometry is precise and reproducible, and can detect true changes in height over one month periods in mid-childhood, and should remain the standard way of observing growth. The book and tape method can produce clinically acceptable quarterly estimations of height that can be performed in the home.
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