Effect of resistance training on body composition, self-efficacy, depression, and activity in postpartum women.

This study assessed the effect of resistance training (RT) in 60 healthy postpartum women. Participants were randomized to 18 weeks of RT or an active comparison group (flexibility training). RT and flexibility training (FT) exercises were completed twice-weekly based on the American College of Sports Medicine recommendations. Study outcomes included muscular strength, body composition (dual-energy x-ray absorptiometry), exercise self-efficacy, depressive symptoms [Center for Epidemiological Studies Depression Scale (CES-D)], and physical activity (accelerometery). For completers (n = 44), the RT group showed greater strength gains than the FT group, respectively (bench press: +36% vs +8%, P < 0.001; leg press: +31% vs +7%, P < 0.01; abdominal curl-ups: +228% vs +43%, P < 0.01); however, body composition changes were not different. There was a significant group × time interaction for exercise self-efficacy (F = 5.33, P = 0.026). For CES-D score, the RT group decreased (F = 4.61, P = 0.016), while the FT group did not; however, the group × time interaction in CES-D score was not significant (F = 1.33, P = 0.255). Sedentary time decreased (F = 5.27, P = 0.027) and light-intensity activity time increased (F = 5.55, P = 0.023) more in the RT than FT group. Intent-to-treat analyses did not alter the results. Twice-weekly RT increases strength and may be associated with better exercise self-efficacy and improved physical activity outcomes compared with FT in postpartum women.

One set resistance training: effect on body composition in overweight young adults.

AIM: This study evaluate the impact of a 6-month, 1-set RT protocol on changes in weight and body composition in overweight young adults. METHODS: Sixty-three overweight young adults were randomized to RT or control; 55 participants (RT: N.=32; C: N.=23; BMI=27.3+2.9; age=20.7+2.7 yrs) competed the 6 month training protocol and all assessments. RT consisted of 1-set, 9 exercises, 3 times/wk., with a resistance of 3-6 repetition maximum (RM). Body composition was assessed using dual energy X-ray absorptiometry, and strength using 1RM. Participants were instructed to maintain their normal ad libitum diet and normal activities of daily living. RESULTS: Body weight and BMI increased significantly (P<0.05) in RT and C, however; the between group difference was not significant. RT induced a mean increase in fat-free mass of 1.5 kg in both males and females with significant between groups differences for change in fat-free mass noted in the total sample, and in both males and females. Between group differences for change in fat mass were not statistically significant in the total sample, or in either gender. Significant between group differences for change in % fat were noted in the total sample (RT=-0.3%, C=+5.8%, P<0.05) and in females (RT=-3.7%, C=+3.0%, P<0.01), but not in males (RT=3.4%, C=9.8%). Significant between group differences (P<0.001) were observed for change in chest (RT=45 %, C=3%) and leg press (RT=57 %, C=9%) maximal strength. CONCLUSION: A 6 month, 1-set RT program in overweight young adults increased fat-free mass and prevented increases in fat mass and % fat.

Effects of long-term aerobic exercise on EPOC.

This study sought to determine the influence of 16 months of progressive aerobic exercise on excess postexercise oxygen consumption (EPOC) and the extent EPOC contributed to weight management. Twenty-five overweight/obese women and 16 overweight/obese men participated in a 16-month exercise program (moderate-intensity treadmill walking) that progressed across the first 26 weeks to 5 days.wk(-1), 45 min.session(-1), and 75% HRR. Three-hour EPOC was measured at baseline, 9 months, and 16 months by indirect calorimetry in response to an exercise session (treadmill walking), in which energy expenditure (EE) was estimated from the participant's previous 10 exercise sessions. For women, EPOC was 7.5 +/- 4.9, 9.6 +/- 7.6, and 6.5 +/- 6.5 L at baseline, 9 months, and 16 months, respectively (p > 0.05). For men, EPOC increased from baseline (11.8 +/- 6.8 L) to 9 months (13.5 +/- 8.6 L) (p < 0.05) with no further increase at 16 months (13.5 +/- 11.0 L). Change in EPOC was correlated with change in EE at 9 months (r = 0.65; p < 0.05) and 16 months (r = 0.58; p < 0.05) for men but not women. Progressive long-term exercise significantly influenced EPOC in overweight/obese men but not women. Change in volume of exercise likely explained the increase in energy expenditure during EPOC in men. EPOC contributed modestly to EE compared to the exercise itself.

A comparison of three methods of analyzing post-exercise oxygen consumption.

Oxygen consumption after exercise is frequently plotted as a function of time and then the area under the curve (AUC) is calculated. Subsequently, this AUC is further manipulated and thus, differences between these manipulations may impact the interpretation of changes in oxygen consumption after exercise. The purpose of this study was to determine if the method of calculating AUC influences the interpretation of changes in post-exercise oxygen consumption in response to long-term aerobic exercise. Forty-three moderately obese, sedentary participants volunteered to participate in this study (26 women and 17 men). All participants performed verified supervised exercise during the study. Supervised treadmill exercise was initially conducted for 3 d/week at 60 % of heart rate reserve (HRR) for 30 min and progressed to 5 d/week at 75 % of HRR for 45 min across the first 4 months. Pre-exercise, exercise, and post-exercise oxygen consumption was measured at baseline and 9 months. AUC was calculated by three methods; total, incremental, and positive incremental. Descriptive statistics and dependent T-tests were calculated for each method of calculating the AUC. In addition, the intra-individual coefficient of variation was determined for each individual for each AUC method. A pearson product moment correlation was calculated for each method to determine the strength of the relationship between pre- and post-training values. The change in post-exercise oxygen AUC after nine months of training was 5.36+/-10.90 L, 2.17+/-7.61 L, and 1.74+/-9.10 L for the total, incremental, and positive incremental methods, respectively. There was significant change in post-exercise total AUC from baseline to 9-months (5.36 +/- 10.90 L), while there was no significant change in incremental or positive incremental AUC. There was a moderately high correlation (r=0.67, p <0.05) between baseline and 9-months for the total AUC method, while there was no significant correlation for incremental and positive incremental AUC methods. These results suggest that the method used to calculate AUC can lead to a different interpretation of the effects of training on post-exercise oxygen consumption. From this data, it appears that analyzing post exercise oxygen consumption with the total area under the curve method has a greater ability to detect a change from aerobic training, than either the positive or incremental area under the curve methods.