Journal of Exercise Science & Fitness

Policies to Increase Physical Activity in Children and Youth

Russell R. Pate, Jennifer L. Trilk, Wonwoo Byun, Jing Wang

The World Health Organization is encouraging countries to develop and implement policies aimed at increasing physical activity in children and adolescents. The purpose of this paper is twofold: (1) to identify the common existing international policies established to increase physical activity in children and adolescents; and (2) to examine the extent to which these policies are supported by solid scientific evidence. Existing policies as well as intervention studies for children and adolescents in Europe, America, Asia, and Oceania that were written in English and Chinese were identified via scientific databases, reference lists of articles, and existing archives and databases via non-electronic search. The policy areas found to be the most common were: (1) Physical Education in School; (2) Physical Activity-Related Health Education; (3) Community Environmental Support; (4) School Environmental Support; (5) Active Transport/Urban Design; and (6) Mass Media/Advertising Campaigns. For these policy areas, the intervention literature was reviewed and segmented into three domains: policy research (studies examining the relationship of policies to physical activity levels in young people), effectiveness studies (multi-site physical activity interventions), and efficacy studies (single site or local physical activity interventions). Effectiveness studies provided support for policies that focus on increasing Physical Education in School, improving School Environmental Support and Active Transport/Urban Design, and launching Mass Media/Advertising Campaigns designed to increase physical activity levels in children and adolescents. The results for Physical Activity-Related Health Education and Community Environmental Support were mixed, indicating that more research is needed to determine the effectiveness of physical activity policies in those areas.

Measuring Children's Physical Activity and Sedentary Behaviors

Paul D. Loprinzi, Bradley J. Cardinal

The high prevalence of overweight and obesity among children necessitates the need to promote physical activity and reduce sedentary behaviors in children. Consequently, there is a need to be able to reliably and accurately measure physical activity and sedentary behaviors in children. Unfortunately, there is no one measurement tool that captures physical activity and sedentary behaviors perfectly. When choosing a measurement tool to assess physical activity and sedentary behavior, researchers and practitioners must be aware of the strengths and limitations of each measurement. To assist researchers and practitioners in choosing the appropriate measurement tool for the desired study, we overviewed the most common methods currently being used to measure physical activity and sedentary behavior in children, noting the strengths and limitations of each instrument.

Play Pattern of Seated Video Game and Active “Exergame” Alternatives

Jessica W.K. Lam, Cindy H.P. Sit, Alison M. McManus

The purpose of the study was to compare the play pattern of “exergames” and seated internet-based video games between boys and girls. Seventy-nine participants (40 boys, 39 girls) aged 9 to 12 years (M = 10.85 ± 0.9) were involved in two 1-hour video game sessions. Play pattern in terms of frequency, duration and intensity were assessed from observation, accelerometry and heart rate monitoring. Results indicated that children spent half of the available time playing the activity-promoting exergames (XaviX bowling 47.6 ± 14.9%; XaviX J-Mat 48.8 ± 12.8%). No differences between the boys and girls were apparent for total time played, number of play bouts or duration per bout (p ≥ 0.05). Boys however played both exergames more actively than the girls (XaviX bowling RT3 counts.s−1: boys 10.47 ± 4.71, girls 6.34 ± 2.76; XaviX J-Mat RT3 counts·s−1: boys 66.37 ± 13.84, girls 51.94 ± 17.83). This study concludes that both boys and girls choose to play exergames for similar periods of time, but play style during the XaviX bowling was often inactive in the girls and during the XaviX J-Mat less active in the girls than the boys. Reasons underlying choice of play was similar between the girls and boys. Active video games appear to be suitable for longer-term physical activity interventions in children, but attention will need to be given to the intensity of game play in girls.

Reliability and Validity of an Incremental Cadence Cycle O2max Testing Protocol for Trained Cyclists

Glen B. Deakin, Allan J. Davie, Shi Zhou

Cycle tests for maximal oxygen uptake ( O2max) have traditionally used incremental resistance protocols (RP) at a constant cadence. The purpose of this study was to evaluate whether an incremental cadence protocol (CP) using a constant resistance relative to gross body mass was as reliable and valid in eliciting O2max as RP in trained cyclists. Ten male recreational cyclists aged 25.2 ± 6.8 years completed two CP and one RP trials in a randomized order over a 3-week period. The CP started at a workload of 2.75 W per kg body mass, with the cadence increased by 10 rpm each minute from 70 rpm. The RP started from 125 W with workload increased 25W each minute with a constant cadence of 90 rpm. The results showed no significant differences between the CP (mean of the two CP trials) and RP for peak O2 (3.9 ± 0.6 vs. 4.0 ± 0.8 L·min−1), peak ventilation (140.5 ± 22.8 vs. 143.0 ± 27.1 L·min−1) and post-exercise blood lactate (11.4 ± 2.1 vs. 11.9 ± 1.6 mmol·L−1), while peak heart rate (183.9 ± 10.5 vs. 187.5 ± 11.4 beats·min−1) and peak workload (319.9 ± 60.2 vs. 375.1 ± 67.3W) were significantly less for the CP than the RP. For the two CP trials, the intraclass correlation coefficient for test-retest reliability was 0.96, the technical error of measurement (TEM) was 0.17 L·min−1, and the relative TEM was 4.35%. The results indicate that the CP is equally effective in eliciting O2max as the RP and is a reliable method of measuring O2max in trained recreational cyclists.

Peak Torque and IEMG Activity of Quadriceps Femoris Muscle at Three Different Knee Angles in a Collegiate Population

Shweta Shenoy, Priyaranjan Mishra, J.S. Sandhu

The coordinated activities of the four heads of the quadriceps femoris muscle results in knee extension. It is still a matter of debate as to whether the different heads of the quadriceps can be activated differentially by the central nervous system at different joint angles. This study aimed to investigate the influence of different angles of knee joint on the activation level of the vastus medialis oblique (VMO), vastus lateralis (VL) and rectus femoris (RF) using electromyographic activity during maximal voluntary isometric contraction (MVIC) and occurrence of peak torque measurement. Forty healthy subjects (20 males, 20 females) participated in the study. The peak torque for the dominant leg was measured using HUR5340 leg extension/curl with simultaneous recording of MVIC of the VMO, VL and RF using surface electromyography (SEMG). Test angles were presented randomly in 30° increments from 30° to 90° of knee flexion. To get peak torque, each subject performed maximal contraction of 10 seconds at each test angle and the myoelectrical activity was recorded simultaneously. The results illustrated that peak torque occurred at 60° for the entire group, including males (F = 39.654, p < 0.001) and females (F = 32, p < 0.001). Significant difference was found in integrated electromyographic (IEMG) activity of the VMO at all the angles in males (F = 14.665, p < 0.001) and females (F = 22.40, p < 0.001), with maximum activity at 60° of knee flexion followed by 90° and then 30° of knee flexion. It was thus concluded that the myoelectrical activity of the VMO changes with change in peak torque at the different joint angles during MVIC in both sexes.

Effect of Diet and Exercise-induced Weight Reduction on Complement Regulatory Proteins CD55 and CD59 Levels in Overweight Chinese Adolescents

Ru Wang, Peijie Chen, Wenhe Chen

Recent studies have suggested that complement plays an important role in adipose tissue homeostasis and insulin resistance, but the involvement of complement regulatory (CReg) proteins in obesity has not been elucidated. In this study, we examined whether weight reduction induced changes in the levels of the CReg proteins CD55 (decay accelerating factor) and CD59 (membrane attack complex inhibitory factor) on blood cells, before and after a 4-week diet and physical exercise intervention. Fourteen overweight Chinese adolescents with a body mass index > 25 kg·(m2)−1 were enrolled, 12 of whom completed the study. CD55 and CD59 levels on cell surfaces were assessed by flow cytometry. It was observed that anthropometric parameters, serum lipid levels, and glycemic-related factors improved significantly post-intervention. On all cells, the CD59 level was significantly increased post-intervention, while the CD55 level on lymphocytes and neutrophils was significantly decreased post-intervention. The pre-intervention CD55 level on lymphocytes positively correlated with the pre-intervention percent body fat (r = 0.737, p < 0.01). This correlation remained significant (r = 0.737, p < 0.01) post-intervention. In conclusion, these observations show that a 4-week diet and exercise program in overweight Chinese adolescents improved physical characteristics, anthropometric parameters, serum lipid levels, and glycemic-related factors. The CD55 level on lymphocytes correlates with percent body fat. Therefore, adipose-derived factors may constitute possible targets for ameliorating overweight and obesity and its adverse metabolic consequences.

Validity of a Pediatric RPE Scale When Different Exercise Intensities are Completed on Separate Days

Jacob E. Barkley, James N. Roemmich

Typically pediatric-specific ratings of perceived exertion (RPE) validation studies have utilized a perceptual estimation paradigm consisting of a single exercise test that incrementally increased in intensity. This may result in an overestimation of concurrent validity as the increases in exercise intensity and participant recall of their previous RPE likely encourages participants to respond with increases in RPE. The purpose of the present study was to assess the concurrent validity of the Cart and Load Effort Rating (CALER) RPE scale in children exercising either above or below the ventilatory threshold (> T, T on another day. Heart rate (HR) and RPE were recorded during the final 20 seconds of each minute of exercise. HR and RPE increased from T (p < 0.001). Univariate correlations demonstrated a moderate relationship between HR and RPE (r = 0.30). Multilevel model regression demonstrated that RPE scores were positively associated with HR (estimate = 2.06 CALER, p < 0.01). Pediatric RPE scores assessed on separate days appropriately increased with exercise intensity and were positively associated with HR. However, the RPE-HR relationships are lower than for research that used exercise tests that incrementally increased in intensity within the same session.

Effects of a Running Bout in the Heat on Cognitive Performance

The aim of this study was to examine the effect of a running bout under hot conditions on cognitive performance in physically active men. Sixteen participants ran at 60% of maximum aerobic speed for an average time of 52.4 ± 7.6 minutes under hot environmental conditions (35°C, 60% relative humidity). Changes in body mass, lean mass, hematocrit, plasma volume, serum urea, creatinine, and thirst score were assessed to evaluate the state of hydration immediately before and after exercise. Cognitive performance was assessed using the Vienna Test System battery before and after exercise. The running protocol led to a decreased body mass, lean mass, plasma volume and an increased hematocrit, serum urea, creatinine and thirst score (all p < 0.05), implying that there was significant impairment in the state of hydration. After the running bout, complex and peripheral reaction time consistently improved, whereas visual angle was impaired (all p < 0.05). A running bout in the heat improves the speed of response in complex tasks but impairs the field of vision and leads to a deleterious hydration state.

Exercise Intervention for Cancer Survivors With Heart Failure

Daniel C. Hughes, Daniel J. Lenihan, Carol A. Harrison, Karen M. Basen-Engquist

Cardiotoxicity is a troubling long-term side effect of chemotherapy cancer treatment, affecting therapy and quality of life. Exercise is beneficial in heart failure patients and in cancer survivors without heart failure, but has not been tested in cancer survivors with treatment-induced heart failure. We present case studies for two survivors: a 56-year-old female Hodgkin's lymphoma survivor (Patient 1) and a 46-year-old male leukemia survivor (Patient 2). We conducted a 16-week exercise program with the goal of 30 minutes of exercise performed 3 times per week at a minimum intensity of 50% heart rate reserve or “12” rating of perceived exertion (RPE). Patient 1 improved from 11.5 minutes of exercise split over two bouts at an RPE of 13 to a 30-minute bout at an RPE of 15. Patient 2 improved from 11 minutes of exercise split over two bouts at an RPE of 12 to an 18-minute bout at an RPE of 12. Both improved in O2peak (Patient 1: 13.9 to 14.3 mLO2·kg−1·min−1; Patient 2: 12.5 to 18.7 mLO2·kg−1·min−1). Ejection fraction increased for Patient 2 (25–30% to 35–40%) but not for Patient 1 (35–40%). Quality of life as assessed by the SF-36 Physical Component Scale improved from 17.79 to 25.31 for Patient 1, and the Mental Component Scale improved from 43.84 to 56.65 for Patient 1 and from 34.79 to 44.45 for Patient 2. Properly designed exercise interventions can improve physical functioning and quality of life for this growing group of survivors.