Moderate-intensity stepping in older adults: insights from treadmill walking and daily living.

BACKGROUND: A step cadence of 100 steps/minute is widely used to define moderate-intensity walking. However, the generalizability of this threshold to different populations needs further research. We investigate moderate-intensity step cadence values during treadmill walking and daily living in older adults. METHODS: Older adults (≥ 60 years) were recruited from urban community venues. Data collection included 7 days of physical activity measured by an activPAL3™ thigh worn device, followed by a laboratory visit involving a 60-min assessment of resting metabolic rate, then a treadmill assessment with expired gas measured using a breath-by-breath analyser and steps measured by an activPAL3™. Treadmill stages were undertaken in a random order and lasted 5 min each at speeds of 1, 2, 3, 4 and 5 km/h. Metabolic equivalent values were determined for each stage as standardised values (METSstandard) and as multiples of resting metabolic rate (METSrelative). A value of 3 METSstandard defined moderate-intensity stepping. Segmented generalised estimating equations modelled the association between step cadence and MET values. RESULTS: The study included 53 participants (median age = 75, years, BMI = 28.0 kg/m2, 45.3% women). At 2 km/h, the median METSstandard and METSrelative values were above 3 with a median cadence of 81.00 (IQR 72.00, 88.67) steps/minute. The predicted cadence at 3 METSstandard was 70.3 (95% CI 61.4, 75.8) steps/minute. During free-living, participants undertook median (IQR) of 6988 (5933, 9211) steps/day, of which 2554 (1297, 4456) steps/day were undertaken in continuous stepping bouts lasting ≥ 1 min. For bouted daily steps, 96.4% (90.7%, 98.9%) were undertaken at ≥ 70 steps/minute. CONCLUSION: A threshold as low as 70 steps/minute may be reflective of moderate-intensity stepping in older adults, with the vast majority of all bouted free-living stepping occurring above this threshold.

Association of working shifts, inside and outside of healthcare, with severe COVID-19: an observational study.

BACKGROUND: Health and key workers have elevated odds of developing severe COVID-19; it is not known, however, if this is exacerbated in those with irregular work patterns. We aimed to investigate the odds of developing severe COVID-19 in health and shift workers. METHODS: We included UK Biobank participants in employment or self-employed at baseline (2006-2010) and with linked COVID-19 data to 31st August 2020. Participants were grouped as neither a health worker nor shift worker (reference category) at baseline, health worker only, shift worker only, or both, and associations with severe COVID-19 investigated in logistic regressions. RESULTS: Of 235,685 participants (81·5% neither health nor shift worker, 1·4% health worker only, 16·9% shift worker only, and 0·3% both), there were 580 (0·25%) cases of severe COVID-19. The odds of severe COVID-19 was higher in health workers (adjusted odds ratio: 2·32 [95% CI: 1·33, 4·05]; shift workers (2·06 [1·72, 2·47]); and in health workers who worked shifts (7·56 [3·86, 14·79]). Being both a health worker and a shift worker had a possible greater impact on the odds of severe COVID-19 in South Asian and Black and African Caribbean ethnicities compared to White individuals. CONCLUSIONS: Both health and shift work (measured at baseline, 2006-2010) were independently associated with over twice the odds of severe COVID-19 in 2020; the odds were over seven times higher in health workers who work shifts. Vaccinations, therapeutic and preventative options should take into consideration not only health and key worker status but also shift worker status.

Device-measured physical activity and its association with physical function in adults with type 2 diabetes mellitus.

AIM: To quantify how differences in metrics characterizing physical activity and sedentary behaviour in type 2 diabetes are associated with physical function. METHODS: This analysis included participants' data from the Chronotype of Patients with Type 2 Diabetes and Effect on Glycaemic Control (CODEC) cross-sectional study. Data were stratified into two groups according to their short physical performance battery (SPPB) score (impaired physical function = SPPB < 10 and normal physical function = SPPB ≥ 10). Hand-grip strength, sit-to-stand 60 (STS-60) and the Duke Activity Status Index (DASI) score were used to assess functional capacity, while physical activity metrics were measured with a wrist-worn accelerometer. The associations between physical activity metrics and measures of functional capacity were analysed using generalized linear modelling. RESULTS: Some 635 adults (median age 66 years, 34% female) were included in this analysis. Overall, 29% of the cohort scored < 10 in the SPPB test indicating impaired physical function. This group spent more time in prolonged sedentary behaviour (600.7 vs. 572.5 min) and undertook less-intense physical activity. Each sd increase in physical activity volume and intensity gradients for those with impaired physical function was associated with 17% more repetitions for STS-60 with similar associations seen for DASI score. Each sd in sedentary time was associated with 15% fewer repetitions in STS-60 and 16% lower DASI score in those with impaired physical function, whereas in normal physical function group it was 2% and 1%, respectively. CONCLUSIONS: The strength of the associations for physical activity measures and functional capacity were modified by physical function status, with the strongest association seen in those with impaired physical function.

Leisure-time physical activity and life expectancy in people with cardiometabolic multimorbidity and depression.

BACKGROUND: Whether and to what extent leisure-time physical activity at the recommended levels of 150-min moderate activity is associated with survival in people with cardiometabolic multimorbidity and depression is unknown. METHODS: UK Biobank participants were classified into groups: (i) no disease; (ii) diabetes; (iii) cardiovascular disease (CVD); (iv) depression; (v) diabetes and CVD; (vi) diabetes and depression; (vii) CVD and depression; (viii) diabetes, CVD and depression. Leisure-time physical activity was categorized as active (meeting recommendations) or inactive. Survival models were applied to estimate life expectancy. RESULTS: A total of 480 940 participants were included (median age, 58 years; 46% men; 95% white), of whom 74% with cardiometabolic multimorbidity and depression were inactive. During a mean follow-up of 7 years, 11 006 deaths occurred. At age of 45 years, being physically active was associated with 2.34 (95% confidence interval: 0.93, 3.54) additional years of life compared with being inactive in participants with diabetes; corresponding estimates were 2.28 (1.40, 3.16) for CVD; 2.15 (0.05, 4.26) for diabetes and CVD; and 1.58 (1.27, 1.89) for no disease. Participants with a combination of diabetes, CVD and depression, being active was associated with 6.81 (-1.50, 15.31) additional years compared with being inactive; corresponding estimates were 3.07 (-2.46, 8.59) for diabetes and depression; 2.34 (-1.24, 5.91) for CVD and depression; and 0.80 (-0.46, 2.05) for depression. A similar pattern was found at 65 years. CONCLUSIONS: Meeting the recommended level of physical activity was associated with a longer life expectancy in people with cardiometabolic multimorbidity but not in those with depression.

Testing the activitystat hypothesis: a randomised controlled trial.

BACKGROUND: It has been hypothesised that an 'activitystat' may biologically regulate energy expenditure or physical activity levels, thereby limiting the effectiveness of physical activity interventions. Using a randomised controlled trial design, the aim of this study was to investigate the effect of a six-week exercise stimulus on energy expenditure and physical activity, in order to empirically test this hypothesis. METHODS: Previously inactive adults (n = 129) [age (mean ± SD) 41 ± 11 year; body mass index 26.1 ± 5.2 kg/m(2)] were randomly allocated to a Control group (n = 43) or a 6-week Moderate (150 min/week) (n = 43) or Extensive (300 min/week) (n = 43) exercise intervention group. Energy expenditure and physical activity were measured using a combination of accelerometry (total counts, minutes spent in moderate to vigorous physical activity) and detailed time use recalls using the Multimedia Activity Recall for Children and Adults (total daily energy expenditure, minutes spent in moderate to vigorous physical activity) at baseline, mid- and end-intervention and 3- and 6-month follow up. Resting metabolic rate was measured at baseline and end-intervention using indirect calorimetry. Analysis was conducted using random effects mixed modeling. RESULTS: At end-intervention, there were statistically significant increases in all energy expenditure and physical activity variables according to both accelerometry and time use recalls (p < 0.001) in the Moderate and Extensive groups, relative to Controls. There was no significant change in resting metabolic rate (p = 0.78). CONCLUSION: Taken together, these results show no evidence of an "activitystat" effect. In the current study, imposed exercise stimuli of 150-300 min/week resulted in commensurate increases in overall energy expenditure and physical activity, with no sign of compensation in either of these constructs. TRIAL REGISTRATION NUMBER: ACTRN12610000248066  (registered prospectively 24 March 2010).

Small Steps: Preliminary effectiveness and feasibility of an incremental goal-setting intervention to reduce sitting time in older adults.

OBJECTIVE: This study aimed to evaluate the preliminary effectiveness and feasibility of a theory-informed program to reduce sitting time in older adults. DESIGN: Pre-experimental (pre-post) study. Thirty non-working adult (≥ 60 years) participants attended a one hour face-to-face intervention session and were guided through: a review of their sitting time; normative feedback on sitting time; and setting goals to reduce total sitting time and bouts of prolonged sitting. Participants chose six goals and integrated one per week incrementally for six weeks. Participants received weekly phone calls. OUTCOME MEASURES: Sitting time and bouts of prolonged sitting (≥ 30 min) were measured objectively for seven days (activPAL3c inclinometer) pre- and post-intervention. During these periods, a 24-h time recall instrument was administered by computer-assisted telephone interview. Participants completed a post-intervention project evaluation questionnaire. Paired t tests with sequential Bonferroni corrections and Cohen's d effect sizes were calculated for all outcomes. RESULTS: Twenty-seven participants completed the assessments (71.7 ± 6.5 years). Post-intervention, objectively-measured total sitting time was significantly reduced by 51.5 min per day (p=0.006; d=-0.58) and number of bouts of prolonged sitting by 0.8 per day (p=0.002; d=-0.70). Objectively-measured standing increased by 39 min per day (p=0.006; d=0.58). Participants self-reported spending 96 min less per day sitting (p<0.001; d=-0.77) and 32 min less per day watching television (p=0.005; d=-0.59). Participants were highly satisfied with the program. CONCLUSION: The 'Small Steps' program is a feasible and promising avenue for behavioral modification to reduce sitting time in older adults.

Assessment of magnetic resonance techniques to measure muscle damage 24 h after eccentric exercise.

The study examined which of a number of different magnetic resonance (MR) methods were sensitive to detecting muscle damage induced by eccentric exercise. Seventeen healthy, physically active participants, with muscle damage confirmed by non-MR methods were tested 24 h after performing eccentric exercise. Techniques investigated whether damage could be detected within the quadriceps muscle as a whole, and individually within the rectus femoris, vastus lateralis (VL), vastus medialis (VM), and vastus intermedius (VI). Relative to baseline values, significant changes were seen in leg and muscle cross-sectional areas and volumes and the resting inorganic phosphate concentration. Significant time effects over all muscles were also seen in the transverse relaxation time (T2) and apparent diffusion coefficient (ADC) values, with individually significant changes seen in the VL, VM, and VI for T2 and in the VI for ADC. A significant correlation was found between muscle volume and the average T2 change (r = 0.59) but not between T2 and ADC or Pi alterations. There were no significant time effects over all muscles for magnetization transfer contrast images, for baseline pH, phosphocreatine (PCr), phosphodiester, or ATP metabolite concentrations or the time constant describing the rate of PCr recovery following exercise.

Accelerometer counts and raw acceleration output in relation to mechanical loading.

The purpose of this study was to assess the relationship of accelerometer output, in counts (ActiGraph GT1M) and as raw accelerations (ActiGraph GT3X+ and GENEA), with ground reaction force (GRF) in adults. Ten participants (age: 29.4 ± 8.2 yr, mass: 74.3 ± 9.8 kg, height: 1.76 ± 0.09 m) performed eight trials each of: slow walking, brisk walking, slow running, faster running and box drops. GRF data were collected for one step per trial (walking and running) using a force plate. Low jumps and higher jumps (one per second) were performed for 20 s each on the force plate. For box drops, participants dropped from a 35 cm box onto the force plate. Throughout, three accelerometers were worn at the hip: GT1M, GT3X+ and GENEA. A further GT3X+ and GENEA were worn on the left and right wrist, respectively. GT1M counts correlated with peak impact force (r = 0.85, p < 0.05), average resultant force (r = 0.73, p < 0.05) and peak loading rate (r = 0.76, p < 0.05). Accelerations from the GT3X+ and GENEA correlated with average resultant force and peak loading rate irrespective of whether monitors were worn at the hip or wrist (r > 0.82, p < 0.05, r > 0.63 p < 0.05, respectively). In conclusion, accelerometer count and raw acceleration output correlate positively with GRF and thus may be appropriate for the quantification of activity beneficial to bone. Wrist-worn monitors show a similar relationship with GRF as hip-worn monitors, suggesting that wrist-worn monitors may be a viable option for future studies looking at bone health.

Increasing children's physical activity: a peer modelling, rewards and pedometer-based intervention.

BACKGROUND/OBJECTIVES: To evaluate a peer modelling, rewards and pedometer-feedback intervention designed to increase children's physical activity and which uses the same behaviour-change principles underlying the Food Dude Healthy Eating Programme. SUBJECTS/METHODS: The study was conducted in two primary schools in Wales. Participants were 47 children (21 boys, 26 girls) from the experimental school and 53 children (29 boys, 24 girls) from a matched control school, aged 9-11 years. Children in the experimental school took part in the intervention; over 8 days they were introduced to fictional role models (the Fit n' Fun Dudes) via visual and audio intervention materials and received small rewards when their daily pedometer step counts increased by 1500 steps per day relative to their baselines. Pedometer measures were taken from children in both schools at baseline, intervention (baseline 2 for the control school) and 12-week follow-up. RESULTS: Among experimental girls, steps per day were significantly higher during the intervention (14 686+/-2540) and at follow-up (13 737+/-3288) compared to baseline (10 864+/-2481, P<0.001) and control girls (P<0.005). Experimental boys showed significantly higher daily steps during the intervention compared to baseline (16 237+/-4204 cf. 13 452+/-3258, P<0.001) and control boys (P<0.005). There were no significant differences between activity levels of experimental and control boys at follow-up. CONCLUSIONS: The intervention resulted in substantial increases in children's physical activity, which was well maintained over a 12-week period in girls.

The prediction of maximal oxygen uptake from submaximal ratings of perceived exertion elicited during the multistage fitness test.

The purpose of this study was to assess whether maximal oxygen uptake (V.O(2 max)) could be predicted from submaximal ratings of perceived exertion (RPE) elicited during the multistage fitness test (MFT). Eleven female volunteers completed three maximal exercise tests in random order; the MFT, a simulated MFT on a motorized treadmill and a graded exercise test to volitional exhaustion (GXT), also on a motorized treadmill. RPE values were recorded at the end of each 1 min stage in all three tests. Oxygen consumption (VO(2)) was recorded continuously during the treadmill tests. Measured V.O(2 max) values from the GXT and simulated MFT were not significantly different (48.2 and 47.5 ml/kg/min, respectively), but they were significantly higher than V.O(2 max) values predicted by the MFT (41.2 ml/kg/min, p<0.05). Regression of submaximal RPE values (7-17) elicited from the MFT and VO(2) values predicted by the MFT were extrapolated to RPE 20 to predict V.O(2 max). The RPE-predicted V.O(2 max) from the MFT (47.5 ml/kg/min) was similar to measured V.O(2 max). The findings suggest that submaximal RPE values can be used to provide acceptable estimates of V.O(2 max) which are more accurate than the published table values for the MFT. Furthermore, the use of RPE measures in conjunction with the MFT enhances the accuracy of V.O(2 max) prediction by the MFT.

Prediction of DXA-determined whole body fat from skinfolds: importance of including skinfolds from the thigh and calf in young, healthy men and women.

OBJECTIVE: To investigate the relationship of percent body fat (%fat), assessed by dual energy-X-ray absorptiometry (DXA) or a four-compartment model, with upper body and lower limb skinfolds. DESIGN: Cross-sectional design involving forward stepwise and hierarchical multiple regression analyses to assess the relationship of %fat with skinfolds and a combination of four commonly used upper body skinfolds (biceps, triceps, subscapular and iliac crest) with the calf and thigh skinfolds. SETTING: University research laboratory. SUBJECTS: In all, 31 females, mean age 20.9 (+/-2.0) y, and 21 males, mean age 22.3 (+/-5.5) y volunteered for this study, which was approved by the Ethics Committee of the School of Sport, Health and Exercise Sciences, University of Wales, Bangor. MEASUREMENTS: %fat from DXA in both groups, and %fat from a four-compartment (water, bone mineral mass, fat and residual) model (%fat4C) in females only. Skinfolds were measured at the abdomen, iliac crest, biceps, triceps, subscapular, calf and thigh. RESULTS: All skinfolds were positively associated with DXA estimates of %fat (P < 0.01). In males and females, the thigh skinfold had the highest correlation with %fat. This was also observed when %fat4C was used as the criterion in females. Stepwise multiple regression analysis using %fatDXA as the criterion selected the thigh (R(2) = 0.82), calf (R(2) change 0.04) and iliac crest (R(2) change = 0.03) for females, and the thigh (R(2) = 0.79), iliac crest (R(2) change = 0.11) and abdomen (R(2) change = 0.03) for males (all P < 0.01). When %fat4C was used as the criterion in the females, only the thigh was selected as a significant predictor (R(2) = 0.76). Independent prediction factors were created from the sum of biceps, triceps, subscapular and iliac crest (sigma4skf) and from the sum of the thigh and calf (sigmathigh + calf). These factors were then entered into a hierarchical multiple linear regression analysis to predict percent fat. Order of entry was varied to allow the assessment of unique variance accounted for by each predictor. The sum of the thigh and calf explained more variance in %fatDXA than that explained by the sigma4skf alone, irrespective of the order of entry in both males and females. This was also observed when %fat4C was used as the criterion in the females. CONCLUSIONS: The results of this study confirm that lower body skinfolds are highly related to percent body fat in fit and healthy young men and women, and uphold current recommendations by the British Olympic Association to include the thigh skinfold with sigma4skf. Conventional use of the sigma4skf to estimate percent body fat is significantly enhanced by the inclusion of the thigh and calf skinfolds, either independently or in combination. In this group of males and females, the sum of the thigh and calf skinfolds accounted for the most variance in percent fat.

Effect of stride length manipulation on symptoms of exercise-induced muscle damage and the repeated bout effect.

This study assessed the effects of stride length on symptoms of exercise-induced muscle damage after downhill running and whether the extent of the symptoms sustained in a repeated bout of downhill running are influenced by stride length manipulation in the first bout. Eighteen males aged 21.1 +/- 0.6 years (mean +/- s) were allocated to one of three groups for bout one: preferred stride frequency, overstride and understride. Bout two was performed 2 weeks later at the participants' preferred stride frequency. Maximal isometric force and perceived muscle soreness were assessed pre-test and 30 min, 24, 48 and 72 h post-exercise for each downhill run. Three-factor analyses of variance with repeated measures on time and bout were used for analysis. Results revealed a three-way interaction for soreness (F8,60 = 3.56, P < 0.05) and relative isometric strength (F5.0,37.8 = 3.2, P < 0.05). Post-hoc analyses revealed that, after bout one, the overstride group perceived most soreness and the understride group retained most strength. After the second bout, the overstride and preferred stride frequency groups perceived less soreness than the preferred stride frequency group in bout one. Strength retention was greater after bout two for all groups. In conclusion, strength retention after a repeated bout appears to be independent of the damage experienced in the initial bout of downhill running. However, understriding may provide least protection against soreness in a subsequent bout.

The effect of type of physical activity measure on the relationship between body fatness and habitual physical activity in children: a meta-analysis.

BACKGROUND: The relationship between activity levels and body fat in children is unclear, despite a large number of studies. The issue is clouded by the wide variety of methods used to assess children's activity levels. It is important to assess whether the type of activity measure influences the fatness-activity relationship. This is a first step to uncovering the role of modifying variables such as gender, age, maturity, etc. PRIMARY OBJECTIVE: This study uses meta-analytic procedures to synthesize the results of such studies and to assess whether the type of activity measure used has an effect on the strength of the relationship observed. METHODS AND PROCEDURES: Fifty studies were located that satisfied the inclusion criteria. Seventy-eight per cent of the studies showed a negative relationship, 18% no relationship and 4% a positive relationship between physical activity and body fatness. Data were analysed using the meta-analytic procedures described by Rosenthal (Meta-analytic Procedures for Social Research, Sage, 1991). MAIN OUTCOMES AND RESULTS: The mean effect size indicated a small to moderate, inverse relationship (r = -0.16). Mean effect sizes differed significantly (F(3,52) = 8.04, p < 0.001) according to the activity measure used: questionnaire, r = -0.14; motion counters, r = -0.18; observation, r = -0.39; heart rate (HR), r = 0.00. Observation measures elicited a significantly stronger relationship with body fat than did questionnaire or heart rate measures (p < 0.05). However, there was no significant difference between the effect sizes elicited by observation and motion counters. Correlational analyses revealed no effect of age group or gender on the strength of the relationship between fatness and activity. CONCLUSIONS: This meta-analysis suggests there is a small to moderate relationship between body fat and activity in children. It is important to note, however, that the size of the relationship depends on the activity measure used. It is therefore recommended that direct measures of movement, such as observation or motion counter methods, are used to assess the relationship of activity levels with health.

Stages in the development of a research project: putting the idea together.

We have considered some of the most important factors involved in designing a viable study that will adequately address the research question. Although we do not profess to be experts in all aspects of the above, we have learned through experience that attention to many of the above points will help to avoid frustration during the experimental process and when the study is presented for external review and subsequent presentation and publication. Good luck in your research.

Relationship between activity levels, aerobic fitness, and body fat in 8- to 10-yr-old children.

The relationships between children's activity, aerobic fitness, and fatness are unclear. Indirect estimates of activity, e.g., heart rate (HR) and recall, may mask any associations. The purpose of this study was to assess these relationships by using the Tritrac-R3D, a pedometer, and heart rate. Thirty-four children, ages 8-10 yr, participated in the study. The Tritrac and pedometer were worn for up to 6 days. HR was measured for 1 day. Activity measured by Tritrac or pedometer correlated positively to fitness in the whole group (Tritrac, r = 0.66; pedometer, r = 0.59; P < 0.01) and in boys and girls separately (P < 0.05) and correlated negatively to fatness in the whole group (r = -0.42, P < 0.05). In contrast, HR did not correlate significantly to fitness, and HR of >139 beats/min correlated positively to fatness in girls (r = 0.64, P < 0.05). This suggests that HR is misleading as a measure of activity. This study supports a positive relationship between activity and fitness and suggests a negative relationship between fatness and activity.

Validity of heart rate, pedometry, and accelerometry for predicting the energy cost of children's activities.

Heart rate telemetry is frequently used to estimate daily activity in children and to validate other methods. This study compared the accuracy of heart rate monitoring, pedometry, triaxial accelerometry, and uniaxial accelerometry for estimating oxygen consumption during typical children's activities. Thirty Welsh children (mean age 9.2 +/- 0.8 yr) walked (4 and 6 km/h) and ran (8 and 10 km/h) on a treadmill, played catch, played hopscotch, and sat and crayoned. Heart rate, body accelerations in three axes, pedometry counts, and oxygen uptake were measured continuously during each 4-min activity. Oxygen uptake was expressed as a ratio of body mass raised to the power of 0.75 [scaled oxygen uptake (sVO2)]. All measures correlated significantly (P < 0.001) with sVO2. A multiple-regression equation that included triaxial accelerometry counts and heart rate predicted sVO2 better than any measure alone (R2 = 0.85, standard error of the estimate = 9.7 ml.kg-0.75.min-1). The best of the single measures was triaxial accelerometry (R2 = 0.83, standard error of the estimate = 10.3 ml.kg-0.75.min-1). It is concluded that a triaxial accelerometer provides the best assessment of activity. Pedometry offers potential for large population studies.

Measurement of physical activity in children with particular reference to the use of heart rate and pedometry.

Understanding the progression of physical activity behaviour from childhood to adulthood requires a valid, reliable and practical method of assessing activity levels which is appropriate for use in large groups. The measurement of physical activity in large scale research projects requires a method which is low in cost, agreeable to the study volunteer and accurate. Self-report can be used to determine adult activity patterns, but children lack the cognitive ability to recall details about their activity patterns. Heart rate telemetry has been used to estimate daily activity in children as a sole criterion and to validate commercial accelerometers. However, heart rate is an indirect estimate of physical activity which makes assumptions based on the linear relationship between heart rate and oxygen uptake. It is sensitive to emotional stress and body position, and takes longer to reach resting levels after physical exertion compared with oxygen uptake. It also lags behind movement, particularly as children's physical activity is spasmodic or intermittent in nature. One alternative is the pedometer. Many early studies reported that the pedometer is inaccurate and unreliable in measuring distance or counting steps. While reasonably accurate at mid range speeds, the accuracy of the pedometer decreases in very slow walking or very fast walking or running. However, more recent studies have examined the efficacy of using pedometers to assess daily or weekly activity patterns as a whole, and these have produced more promising results. In this regard, the pedometer has a number of advantages. It is very cheap, objective and does not interfere with daily activities and is therefore appropriate for use in population studies. Commercial accelerometers with a time-sampling mechanism offer further potential and could be used to provide a picture of the pattern of children's activity. As it has been observed that prolonged activity periods are not typically associated with childhood behaviour patterns, the use of a threshold value for 'aerobic' training stimulus is not appropriate as a cut-off value for physical activity. Instead, there is evidence to suggest that the total activity data measured by pedometers over limited periods of time may be more appropriate to assess how active children are.