The purpose of the current study was to determine whether expected changes in body weight via a 3-day low-carbohydrate (LC) diet will disrupt the reliability of air displacement plethysmography measurements via BOD POD. Twenty-four subjects recorded their typical diets for 3 days before BOD POD and 7-site skinfold analyses. Subjects were matched for lean body mass and divided into low-CHO (LC) and control (CON) groups. The LC group was given instruction intended to prevent more than 50 grams/day of carbohydrate consumption for 3 consecutive days, and the CON group replicated their previously recorded diet. Body composition measurements were repeated after dietary intervention. Test–retest reliability measures were significant (p < .01) and high for body fat percentage in both the LC and the CON groups (rs = .993 and .965, respectively). Likewise, skinfold analysis for body fat percentage reliability was high in both groups (rs = .996 and .997, respectively). There were significant differences between 1st and 2nd BOD POD measurements for body mass (72.9 ± 13.3 vs. 72.1 ± 13.0 kg [M ± SD]) and body volume (69.0 ± 12.7–68.1 ± 12.2 L) in the LC group (p < .05). However, there were no differences (p > .05) in BOD POD–determined body fat percentage, lean body mass, or fat mass between the 1st and 2nd trial in either group. Body composition measures via BOD POD and 7-site skinfolds remain reliable after 3 days of an LC diet despite significant decreases in body mass.
Beau Kjerulf Greer, Kathleen M. Edsall and Anna E. Greer
Robert Gorinski and Wendy Stuhldreher
Stuart J. Fairclough
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.
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.
Jennifer Gornall and Rudolph G. Villani
The primary aim was to investigate whether the reduction in resting metabolic rate (RMR) and fat free mass (FFM) associated with a short-term very low kilojoule diet (VLKD) is altered by concurrent resistance exercise. Twenty overweight, premenopausal women were pair matched on body surface area and randomly assigned to either diet only (3,400 kJ/day) or diet combined with resistance training. Before and after 4 weeks of treatment, RMR was assessed by indirect calorimetry; total body mass (TBM), FFM, and fat mass (FM) by dual energy x-ray absorptiometry; total body water (TBW) by bioelectrical impedance; and strength by a weight-lifting test. Both groups had significantly lower TBM, FFM, FM, TBW, absolute RMR, and RMR, with FFM as the covariate, in the posttests than the pretests with no significant differences between groups. It was concluded that 4 weeks of resistance training did not prevent or reduce the decline in FFM and RMR observed with a VLKD.
Ezzedine Bouhlel, Myriam Denguezli, Monia Zaouali, Zouhair Tabka and Roy J. Shephard
To evaluate the effect of Ramadan fasting on parameters of insulin resistance in trained athletes at rest and after aerobic exercise.
Nine male rugby players (age 19 ± 2 yr, height 1.78 ± 0.74 m) were tested 3 times: 1 week before observance of Ramadan (C), at the end of the first week (R1), and during the fourth week (R2). They performed a progressive cycle-ergometer test at each visit. Data collected at rest and at the end of aerobic exercise included simple anthropometry (body mass, body-mass index, body fat, fat-free mass), biochemical parameters (serum glucose, cholesterol, HDL cholesterol, triglycerides, creatinine, and serum proteins), and selected hormone concentrations (plasma insulin, leptin, and adiponectin).
Ramadan fasting was associated with a reduction of body mass and body fat (R2 vs. C, p < .01) without significant change in leptin or adiponectin levels.
Lipolysis might have occurred because of increased plasma triglycerides and HDL cholesterol concentrations.
Kenneth H. Pitetti, Daniel A. Yarmer and Bo Fernhall
The purpose of this study was to compare the aerobic fitness and body mass index (BMI) of children and adolescents (8-18 yr) with and without mild mental retardation (MR). Sample size of participants with MR but without Down syndrome was 169 males and 99 females. Sample size of participants without MR was 289 males and 317 females. Analysis was made by gender and age: children (8-10 yr); early adolescents (11-14 yr); and late adolescents (15-18 yr). The 20-m shuttle run test (20 MST) was used to assess field test performance and predicted aerobic fitness. For all age groups, females and males without MR ran significantly more laps and had a significantly higher predicted aerobic fitness (V̇O2peak: ml $$ kg-1 $$ min-1) than their peers with MR. Additionally, participants with MR tended to have higher BMI than their peers without MR. The results of this study indicate that children and adolescents with MR have lower exercise capacity, lower aerobic fitness, and higher BMIs than their peers without MR.
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.
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.