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Ferdous Wahid, Rezaul Begg, Noel Lythgo, Chris J. Hass, Saman Halgamuge and David C. Ackland

Normalization of gait data is performed to reduce the effects of intersubject variations due to physical characteristics. This study reports a multiple regression normalization approach for spatiotemporal gait data that takes into account intersubject variations in self-selected walking speed and physical properties including age, height, body mass, and sex. Spatiotemporal gait data including stride length, cadence, stance time, double support time, and stride time were obtained from healthy subjects including 782 children, 71 adults, 29 elderly subjects, and 28 elderly Parkinson’s disease (PD) patients. Data were normalized using standard dimensionless equations, a detrending method, and a multiple regression approach. After normalization using dimensionless equations and the detrending method, weak to moderate correlations between walking speed, physical properties, and spatiotemporal gait features were observed (0.01 < |r| < 0.88), whereas normalization using the multiple regression method reduced these correlations to weak values (|r| < 0.29). Data normalization using dimensionless equations and detrending resulted in significant differences in stride length and double support time of PD patients; however the multiple regression approach revealed significant differences in these features as well as in cadence, stance time, and stride time. The proposed multiple regression normalization may be useful in machine learning, gait classification, and clinical evaluation of pathological gait patterns.

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Nicholas M. Edwards, Philip R. Khoury, Heidi J. Kalkwarf, Jessica G. Woo, Randal P. Claytor and Stephen R. Daniels

Establishing and maintaining healthy physical activity (PA) levels is important throughout life. The purpose of this study was to determine the extent of PA tracking between ages 3 and 7 y. Objective measures of PA (RT3, triaxial accelerometer) were collected every 4 mo from ages 3–7; data from 234 children with PA measures available during each year of age were analyzed. Mean PA (total, moderate/vigorous (MV), and inactivity [IA]) was calculated for each year of age and adjusted for wear time. Correlations with age 3 PA were moderate at age 4 (r = .42−.45) but declined by age 7 (r = .19−.25). After classification into sex-specific tertiles of PA at age 3, boys in the high age 3 MVPA tertile maintained significantly higher PA at all subsequent ages, while girls in the high age 3 MVPA tertile were not significantly higher at age 6 and 7. Boys and girls in the high age 3 IA tertile had significantly higher IA at multiple subsequent years of age (p < .05 at ages 5 and 6). In conclusion, boys who were relatively more active at age 3 remained more active for several subsequent years. These findings highlight early-childhood differences in physical activity patterns between boys and girls.

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David Diggin, Ross Anderson and Andrew J. Harrison

Evidence suggests reports describing the reliability of leg-spring (kleg) and joint stiffness (kjoint) measures are contaminated by artifacts originating from digital filtering procedures. In addition, the intraday reliability of kleg and kjoint requires investigation. This study examined the effects of experimental procedures on the inter- and intraday reliability of kleg and kjoint. Thirty-two participants completed 2 trials of single-legged hopping at 1.5, 2.2, and 3.0 Hz at the same time of day across 3 days. On the final test day a fourth experimental bout took place 6 hours before or after participants’ typical testing time. Kinematic and kinetic data were collected throughout. Stiffness was calculated using models of kleg and kjoint. Classifications of measurement agreement were established using thresholds for absolute and relative reliability statistics. Results illustrated that kleg and kankle exhibited strong agreement. In contrast, kknee and khip demonstrated weak-to-moderate consistency. Results suggest limits in kjoint reliability persist despite employment of appropriate filtering procedures. Furthermore, diurnal fluctuations in lower-limb muscle-tendon stiffness exhibit little effect on intraday reliability. The present findings support the existence of kleg as an attractor state during hopping, achieved through fluctuations in kjoint variables. Limits to kjoint reliability appear to represent biological function rather than measurement artifact.

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Kate Giles and Alison L. Marshall

Background:

One- to two-week test–retest reliability and construct validity (against pedometer step counts) of the CHAMPS physical activity questionnaire were evaluated in older Australian adults.

Methods:

Participants (n = 100, age >65 years) were invited to complete CHAMPS by mail. Spearman correlation coefficients are reported for physical activity constructs time (min/wk) and sessions per week for walking, moderate-, and vigorous-intensity activity and total physical activity. Correct classification of participants as meeting physical activity recommendations was assessed using percent agreement and kappa statistics.

Results:

Seventy-three participants completed CHAMPS at T1; 54 provided repeat data (T2). Sixty percent of the participants provided complete data. Good to excellent test– retest reliability was observed for all the physical activity constructs (r s = .70 to .89 for sessions/wk and r s = .65 to .75 for min/wk). Agreement between proportions classified as meeting recommendations at T1 and T2 was good (79%; kappa = 0.55). Fair to low validity coefficients were observed between steps and T1 CHAMPS walking and total activity sessions/wk (r s = .57 and r s = .52), and min/wk (r s = .40 and r s = .21).

Conclusions:

Mailed self-complete CHAMPS data provided reliable and valid estimates of physical activity in older Australian adults. Observed measurement coefficients were comparable to those reported in previous evaluations of CHAMPS. Further work is required to identify strategies to prevent data loss.

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Tiego A. Diniz, Fabricio E. Rossi, Clara Suemi da Costa Rosa, Jorge Mota and Ismael F. Freitas-Junior

The objective of this study was to compare moderate-to-vigorous physical activity (MVPA), minutes per week (min/wk), and fulfillment of the current recommendation (150 min/wk of MVPA) based on different cut-points in postmenopausal women. The sample was composed of 233 postmenopausal women aged 59.8 ± 6.7 years old. MVPA was measured using triaxial accelerometers. Accelerometers were initialized to collect in 60-s epochs. Participants were included if using at least 5 days. MVPA min/wk were obtained using Freedson, Troiano, Copeland, and Sasaki cut-points. Box-plot indicated large mean differences between almost all cut-points, except for Freedson and Troiano (9.3 [95% LoA: –5.6; 24.3] min/wk). The proportion of women who achieved 150 min/wk of MVPA was similar between Freedson and Troiano (31% vs. 30%). Sasaki and Copeland cut-points resulted in a greater proportion than other cut-points. We concluded that the cut-points analyzed generated different results in MVPA min/wk and low agreement when using current guidelines for MVPA pattern classification, except for the comparisons between Freedson and Troiano cut-points.

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Ansku Holstila, Ossi Rahkonen, Eero Lahelma and Jouni Lahti

Background:

The association between changes in physical activity and sickness absence is poorly understood. The aim of this study was to examine the association between changes in leisure-time physical activity and long-term sickness absence due to any cause and musculoskeletal and mental causes.

Methods:

We measured physical activity at baseline in 2000–2002 (response rate 67%) and at follow-up in 2007 (response rate 83%) among middle-aged employees of the City of Helsinki, Finland. The survey data were linked to the Finnish Social Insurance Institute’s register data on sickness benefit periods > 9 days, including diagnoses (ICD-10; International Statistical Classification of Diseases and Related Health Problems, 10th revision) (mean follow-up 2.3 years). We used a negative binomial model to calculate rate ratios. The analyses included 4010 respondents (81% women).

Results:

Those who were persistently vigorously active and those whose physical activity level changed from low to moderate or vigorous, from moderate to vigorous, or from vigorous to moderate were at lower risk for sickness absence than were the persistently low-activity group. For sickness absence due to musculoskeletal causes, vigorous activity showed stronger associations, whereas mental causes showed no such associations.

Conclusions:

To reduce sickness absence due to both musculoskeletal and mental causes, middle-aged and aging employees should be encouraged to engage in physical activity.

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Naoki Kikuchi, Dai Ueda, Seok-ki Min, Koichi Nakazato and Shoji Igawa

Purpose:

To examine the relationship between ACTN3 polymorphisms and level of athletic performance in Japanese wrestlers.

Methods:

The control group consisted of 243 healthy Japanese individuals. The authors divided 135 wrestlers into 3 groups based on their results in national or international competitions. They classified as elite 24 wrestlers who had placed in the top 8 in a world championship or participated in Olympic games, 28 wrestlers who had participated in world championships or become champions in Japan’s national championships were classified as subelite, and 83 wrestlers were classified as national (N-W, ie, national-level wrestler). In addition, the authors combined the elite and subelite to form the classification international-level wrestlers (I-W).

Results:

The frequency of the null X allele and the XX genotype were significantly lower in the I-W group than in the control group. However, there was no significant difference in ACTN3 genotype or allele frequency between the N-W and control groups. The frequency of the ACTN3 XX genotype in the elite groups was lower than that of all groups, and a linear tendency was observed between ACTN3 XX genotype and athletic status.

Conclusions:

In conclusion, the data indicated that ACTN3 polymorphisms were related to athletic performance in Japanese wrestlers.

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Meke Mukeshi, Bernard Gutin, William Anderson, Patricia Zybert and Charles Basch

The validity of the Caltrac movement sensor for use with preschool children was assessed. Caltrac-derived values for energy expenditure were compared with those derived via laborious coding of direct observation that involved classification of the child’s videotaped activity every other 5 seconds for an hour in the day-care center or on the playground. Both Caltrac and direct observation values were expressed in kilocalories. The subjects were 20 children with a mean age of 35 months. The correlation coefficient for the total of indoor and outdoor activity was r= .62 (p<.01). The separate correlations for indoor and outdoor activity were r=.56 (p<.05) and r=.48 (p<.05), respectively. However, when the children’s weight, height, age, and sex were factored out of both the Caltrac and direct observation scores, the correlations fell to r= .25 (n.s.), r= .47 (p<.05), and r=.16 (n.s.) for the total, indoor, and outdoor activity, respectively. Thus the Caltrac seemed to record indoor activity (mainly walking) more accurately than it recorded the more varied playground movements, casting doubt on its value as a means of measuring physical activity in children 2-3 years of age.

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Jennifer L. Gay, Harold W. Kohl III, Jennifer J. Salinas, Joseph B. McCormick and Susan P. Fisher-Hoch

Background:

The association between light-intensity activity and cardiovascular disease risk is not well understood. The purpose of this study was to determine the association of light-intensity activity with census-based occupational activity classifications and cardiovascular risk factors among Mexican American adults.

Methods:

118 Mexican American adults (68.6% female) provided cross-sectional accelerometer and biological data. Self-reported occupations were classified by activity level (sedentary, low, moderate). Participants were classified as At-Risk for BMI, glucose, triglycerides, HDL, blood pressure, waist circumference, and percent body fat.

Results:

Participants engaged in > 5 hours of light-intensity activity on average, and those in sedentary occupations engaged in fewer light-intensity activity minutes than low-active or moderately active workers (P < .001). Self-reported occupation explained 14% of the variation in light-intensity activity (P < .001). Participants in moderately active occupations were at increased risk for high %body fat than other workers (P = .01), but no other associations between occupation and cardiovascular risk were detected.

Conclusion:

Early work in physical activity underscored the importance of occupational activity. This study presents evidence of a dose-response association for light-intensity activity by occupational category such that workers in sedentary occupations had less light-intensity activity than employees in more active occupations. Future research on how light-intensity activity derived from occupation may reduce the risk of chronic disease will contribute to improved interventions as light-intensity activity participation may be more feasible than meeting current physical activity guidelines.

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Grace E. Figley

The development of positive attitudes toward physical education has been a longstanding and desirable goal of the program of physical education. The intent of this investigation was to identify those aspects of the program students reported as turning them on to or turning them off from physical education. The critical incident report was the tool used to gather information. The subjects (N = 100) classified the reported incidents as either positive or negative, and their comments were then categorized into five broad categories: (a) teacher, (b) curriculum, (c) atmosphere of the classroom, (d) peer behavior, and (e) perceptions of self. Further classification occurred within each category. The results indicated that the items most frequently mentioned in relation to both positive and negative attitudes related to the teacher and the curriculum. Some interesting patterns evolved both within and between the various categories. The most encouraging aspect of the investigation is that the great majority of causal determinants of negative attitudes are amenable to change. If physical educators value the goal of developing positive attitudes toward physical education, then information gathered in studies such as this should prove valuable to both current physical educators and those involved in teacher education programs.