This study assessed the physical activity levels of 20 high school girls (age 13 years, SD = 1.1) during physical education classes, over an 8-month period. Physical activity was measured by heart rate telemetry and accelerometry. Skinfold measurements were used to estimate percent body fat, and peak VO2 was assessed by maximal treadmill running. Girls engaged in moderate-to-vigorous intensity physical activity (MVPA) for 38.5% of class time and produced 961.8 vector magnitude (Vmag) counts · min−1. Body fat was inversely correlated with Vmag counts · min−1 (r = −.65, p < .01) and peak VO2 (r = −.65, p < .01). Girls’ MVPA in physical education did not meet the Healthy People 2010 50% of class time criterion. Body fat significantly predicted 42% of the variance in Vmag counts · min−1. Cardiorespiratory fitness appeared not to influence physical activity during physical education, regardless of measurement method. Girls’ physical activity in physical education may be improved if schools advocate planned lesson outcomes that aim to maximize opportunities for physical activity.
Lee E.F. Graves, Nicola D. Ridgers, Greg Atkinson and Gareth Stratton
Active video game interventions typically provide children a single game that may become unappealing. A peripheral device (jOG) encourages step-powered gaming on multiple games. This trial evaluated the effect of jOG on children’s objectively measured PA, body fat and self-reported behaviors. 42 of 58 eligible children (8–10 y) randomly assigned to an intervention (jOG) or control (CON) completed the trial. Intervention children received two jOG devices for home use. Analyses of covariance compared the intervention effect at 6 and 12 weeks from baseline. No differences were found between groups for counts per minute (CPM; primary outcome) at 6 and 12 weeks (p > .05). Active video gaming increased (adjusted change 0.95 (95% CI 0.25, 1.65) h·d−1, p<.01) and sedentary video gaming decreased (-0.34 (-1.24, 0.56) h·d−1, p > .05) at 6 weeks relative to CON. No body fat changes were observed between groups. Targeted changes in video game use did not positively affect PA. Larger trials are needed to verify the impact of active video games on children’s PA and health.
Peter Pagels, Anders Raustorp, Trevor Archer, Ulf Lidman and Marie Alricsson
Health organizations suggest that adults ought to engage in at least 30 minutes of moderate-intensity daily physical activity. This study investigated the effects of a 30-minute single daily bout of brisk walking upon risk factors for coronary heart disease with blood lipid profile in particular.
Thirty-three (25–45 y) adults, were randomly assigned into an exercise group (EG; n = 16, 9w) and a control group (CG; n = 17, 6w). The EG walked briskly 30 minutes daily during the 3-week test period. Compliance/adherence was maximal throughout the 3-week intervention due to stringent daily monitoring.
The EG showed a significant decrease in concentrations of low density lipoprotein cholesterol (LDL-C) and total cholesterol (TC) during the intervention period. A significant inverse correlation between Δ energy expenditure/day and Δ LDL-C (r = –0.39, P < .05) and an improvement in weight and BMI in the EG was found. Average steps during 30 minutes brisk walking bout was 3669 steps/bout generating a mean energy expenditure of 191 kcal/ bout.
The most unique findings were that daily single bouts of moderate-intensity physical activity for 30 minutes, during 3 weeks, induced favorable effects upon body weight, BMI, and blood concentration of LDL-C and TC in healthy adults.
To examine variations in physical, physiological, and performance parameters over an annual training cycle in a world champion rowing crew.
Four world-class rowers, all of them members of the men’s heavyweight quadruple sculls squad who are current world rowing champions, were assessed 3 times at regular 4-mo intervals during the 2011 season (November 2010, March 2011, and July 2011). Physical assessments included stature, body mass, body composition, whereas physiological and performance assessments obtained during an incremental rowing ergometer test to exhaustion included maximum oxygen uptake and anaerobic gas-exchange threshold with corresponding power output values.
Body mass (∼95 kg) and body composition (∼12% body fat) remained stable over the annual training cycle. Power output at anaerobic gas-exchange threshold increased +16% from November to July, whereas the corresponding oxygen uptake, expressed as a percentage of maximum oxygen uptake, increased from 83% to 90%. Maximum oxygen uptake decreased from 6.68 L/min in November to 6.10 L/min in March before rising to 6.51 L/min in July. The corresponding power output increased steadily from 450 W to 481 W.
Seasonal variation in body mass and body composition of 4 examined world-class rowers was minimal. Oxygen uptake and power output corresponding to anaerobic threshold continuously increased from off-season to peak competition season. Seasonal variation in maximum oxygen uptake reached ∼10%; however, it remained above 6 L/min, that is, the value consistently observed in top caliber heavyweight rowers regardless of the time of the assessment.
Jennifer W. Bea, Robert M. Blew, Carol Howe, Megan Hetherington-Rauth and Scott B. Going
This systematic review evaluates the relationship between resistance training and metabolic function in youth.
PubMed, Embase, Cochrane Library, Web of Science, CINAHL, and ClinicalTrials. gov were searched for articles that (1): studied children (2); included resistance training (3); were randomized interventions; and (4) reported markers of metabolic function. The selected studies were analyzed using the Cochrane Risk-of-Bias Tool.
Thirteen articles met inclusion criteria. Mean age ranged from 12.2 to 16.9 years, but most were limited to high school (n = 11) and overweight/obese (n = 12). Sample sizes (n = 22–304), session duration (40–60min), and intervention length (8–52 wks) varied. Exercise frequency was typically 2–3 d/wk. Resistance training was metabolically beneficial compared with control or resistance plus aerobic training in 5 studies overall and 3 out of the 4 studies with the fewest threats to bias (p ≤ .05); each was accompanied by beneficial changes in body composition, but only one study adjusted for change in body composition.
Limited evidence suggests that resistance training may positively affect metabolic parameters in youth. Well-controlled resistance training interventions of varying doses are needed to definitively determine whether resistance training can mitigate metabolic dysfunction in youth and whether training benefits on metabolic parameters are independent of body composition changes.
Eric T. Poehlman and Christopher Melby
In this brief review we examine the effects of resistance training on energy expenditure. The components of daily energy expenditure are described, and methods of measuring daily energy expenditure are discussed. Cross-sectional and exercise intervention studies are examined with respect to their effects on resting metabolic rate, physical activity energy expenditure, postexercise oxygen consumption, and substrate oxidation in younger and older individuals. Evidence is presented to suggest that although resistance training may elevate resting metabolic rate, il does not substantially enhance daily energy expenditure in free-living individuals. Several studies indicate that intense resistance exercise increases postexercise oxygen consumption and shifts substrate oxidation toward a greater reliance on fat oxidation. Preliminary evidence suggests that although resistance training increases muscular strength and endurance, its effects on energy balance and regulation of body weight appear to be primarily mediated by its effects on body composition (e.g., increasing fat-free mass) rather than by the direct energy costs of the resistance exercise.
Christie L. Ward, Rudy J. Valentine and Ellen M. Evans
Adiposity, lean mass, and physical activity (PA) are known to influence physical function in older adults, although the independent influences are not completely characterized. Older adults (N = 156, M age = 68.9 ± 6.7 yr, 85 men) were assessed for body composition via dual-energy X-ray absorptiometry, PA by accelerometer, and physical function via timed up-and-go (UP&GO), 30-s chair stand, 6-min walk (6-min WALK), and Star-Excursion Balance Test. In the absence of percentage-body-fat by PA interactions (p > .05), main effects existed such that a higher percentage body fat was associated with poorer performance in UP&GO, 30-s chair stand, and 6-min WALK (p < .05). No significant main effects were found for PA and functional performance. Adiposity explains 4.6–11.4% in physical functional variance (p < .05). Preventing increases in adiposity with age may help older adults maintain functional independence.
Heidi K. Byrne and Jack H. Wilmore
The present cross-sectional study was designed to investigate the relationship between exercise training and resting metabolic rate (RMR). The focus of this investigation was to compare RMR in aerobically trained (AT), resistance trained (RT), and untrained (UNT) women. Subjects were also classified as highly trained (HT), moderately trained (MT), or untrained (UNT) in order to examine the relationship between RMR and level of training. Sixty-one women between the ages of 18 and 46 years volunteered to serve as subjects in this study. Each subject completed measurements of body composition, maximal oxygen uptake (V̇O2max), and two consecutive measurements of RMR. The data presented show that there was no significant difference in resting metabolic rate between resistance-trained, aerobically trained, and control subjects. However, when grouped by intensity of training, there was a trend for an increased resting metabolic rate (kcal/day) in the highly trained subjects, regardless of mode of training.
Robert C. Eklund and Sally Crawford
The purpose of this investigation was to replicate and extend Crawford and Eklund's (1994) investigation of social physique anxiety (SPA) and exercise. Women (N = 94) enrolled in physical education activity or major classes participated in the investigation. Data were collected on SPA, weight satisfaction, percent body fat, reasons for exercise, exercise behaviors and preferences, and attitudes toward two aerobic class video presentations featuring a manipulation of physique salience. Consistent with the previous investigation, self-presentational reasons for exercise (body tone, weight control, and physical attractiveness) were positively associated with SPA in both simple correlations and hierarchical analyses controlling for body composition. In contrast to previous findings, SPA was not associated with favorability of attitudes toward either of the video presentations. The inability to fully replicate Crawford and Eklund's (1993) findings raised interesting questions with regard to variables that may moderate or mediate self-presentational anxiety in exercise settings.