Analyzing Sex Differences and the Dose-Response Relationship Between Aerobic Exercise and Cognitive Processing Speed in Young Active Adults

Available research has identified a positive relationship between 10 minutes of aerobic exercise and improvements in cognitive processing speed (CPS) in young adults, although participant activity level was unclear Additionally, research indicates possible sex differences concerning exercise and CPS, defined as the rate in which human beings take in information and generate a response. PURPOSE: To investigate the potential effects of aerobic exercise bout length on cognitive processing speed in active adults. A secondary aim was to explore differences in CPS and aerobic exercise bout length between sexes. METHODS: Male (n=6) and female (n=6) participants who were classified as physically active based on ACSM guidelines participated in aerobic exercise sessions of different bout lengths (15, 20, and 25 minutes) in a balanced cross-over design. When participants arrived for the three testing trials, they first completed a computerized Symbol Search test. This matching test lasts two minutes and provides a score based on how many matches they answer correctly. Next, the exercise treatment consisted of a 5-minute warm-up, followed by a moderate intensity walk or jog on the treadmill (approximately 50-59% of Heart Rate reserve), and ending with a 5-minute cooldown. Participants then remained seated for ten minutes to allow for their heart rate to return to a resting state. Once in the resting state participants were administered the symbol search test again to determine if there were any changes in CPS following an exercise bout. All treatment sessions were performed at least 24 hours apart. Exercise bout length (T15, T20, T25) and time (pre-/post- exercise) were compared between sexes (M, F) using an ANOVA (1 between, 2 within) α=0.05. RESULTS: The main effects for bout length (p=0.849) and sex (p=0.232), bout length x sex interaction (p=0.563), bout length x time interaction (p=0.491), and bout length x time x sex interaction (p=0.956) were not significant. However, the main effect for time was significant (p=0.0001) where CPS was faster post-exercise (50+9) than pre-exercise (45+9) when pooled across bout length and sex. Also, there was a significant time x sex interaction (p=0.009) where, when pooled across bout length, there was greater CPS improvement from pre- to post-exercise in the males (Pre 46+8, Post 53+8) than in the females (Pre 43+11, Post 46+9). CONCLUSION: Active individuals experience improvements in CPS following an exercise bout. We did not find any significant distinction between bout lengths, indicating that active individuals do not require a specific exercise dose time to elicit improvements in CPS. However, male participants had a statistically significant increase in their processing speed assessment (pre-/post- exercise) compared to the females. This suggests that females may require additional exercise bouts or alternate exercise forms to experience similar improvements as the male participants

The Effect of Rest Interval Length on Upper and Lower Body Exercises in Resistance-Trained Females

International Journal of Exercise Science 14(7): 1178-1191, 2021. The purpose of this study was to investigate the effects of SHORT (1 min) and LONG (3 min) rest intervals (RI) on total volume lifted (TVL), repetition performance, fatigue index (FI), and blood lactate [La] during upper body (chest press) and lower body (leg press) exercise with low-intensity (75% of a 10-RM) in trained female lifters. Fourteen females (mean ± SD, age = 22.9 ± 5.4 years, training experience = 5.2 ± 2.5 years, height = 166.1 ± 6.9 cm, weight = 61.3 ± 5.1 kg, body fat % = 21.7 ± 3.3%) participated in this randomized, repeated-measures, cross-over design study. They performed four sets to failure on chest press (CP) and leg press (LP) under two conditions (SHORT and LONG RIs) in a counterbalanced manner. Paired-samples t-tests were used to analyze mean differences for TVL in CP and LP, separately. A 2 (exercise) x 2 (rest interval) repeated measures ANOVA was used to analyze mean differences in FI and average [La] values. A 2 (rest interval) x 4 (sets) repeated measures ANOVA was used to analyze mean differences in repetitions completed for each exercise. TVL for SHORT was significantly less when compared to LONG for both exercises. There was no significant difference in average [La] between RIs despite a greater FI in SHORT compared to LONG for both exercises. Lastly, [La] was higher during LP compared to CP irrespective of RI length. These results suggest that longer RIs are better for female lifters who want to optimize TVL with low-intensity resistance training. Metabolic stress, as measured by blood lactate, was greater during lower-body exercise

A Comparison of Multiple Body Composition Measurement Methods to the Department of Defense’s Physical Fitness and Body Fat Program Procedures

INTRODUCTION: The Department of Defense (DoD) developed body composition standards that require service personnel to meet sex- and branch-specific body mass index criteria. Failing to meet these criteria leads to body fat percentage (%BF) estimation via the DoD’s circumference method. Service members exceeding these standards face administrative action and a possible premature discharge, thus emphasizing the importance of accurately estimating %BF with this method. PURPOSE: To compare the predictive accuracy of the DoD’s circumference-based equation to estimate %BF compared to hydrostatic weighting (HW); segmental and whole-body bioelectrical impedance analyses (BIA), and sex-specific skinfold thickness assessments. METHODS: Physically active men (n = 35, 25 ± 4.7 yrs, 79.6 ± 21 kg, 176.3 ± 6.7 cm) and women (n = 34, 24.7 ± 5.1 yrs, 63.6 ± 8.6 kg, 166.0 ± 7.3 cm) participated. Population-specific equations were used to compute body density (Db) from ΣSKF and HW and to convert Db to %BF. Sex-specific repeated measures ANOVAs with Bonferroni’s multiple comparisons tests were applied. Agreement between the DoD and the other %BF results were quantified via Bland-Altman 95% limits-of-agreement plots. Statistical significance was set at p\u3c.05. RESULTS: The DoD method predicted a significantly (p\u3c.05) higher %BF (27.1 ± 6.3%) compared to upper body BIA (23.1 ± 4.9%) and SKF (21.9 ± 4.8%) for the women only. For men, the DoD method estimated a significantly lower (p\u3c.05) %BF (12.9 ± 5.5%) compared to lower body BIA (17.5 ± 5.7%). Wide limits-of-agreement (\u3e ±3.5 %BF) for mean differences in %BF were observed between the DoD method and all assessments for both men and women. CONCLUSION: Our findings suggest that at the group level, the DoD’s current method of assessing %BF produces similar values compared to whole-body vertical BIA and HW. However, DoD estimates of %BF at the individual level lack predictive accuracy given the wide limits-of-agreement. Since the DoD method is applied at the individual level, caution is needed when determining if administrative action is necessary