The purpose of this study was to determine the relationship between changes in heart rate variability (HRV), neuromuscular performance, and fatigue biomarkers in response to a resistance exercise bout. The root mean square of successive RR interval differences (RMSSD), neuromuscular performance - isometric handgrip (IHG), countermovement jump (CMJ), mean propulsive velocity (MPV) - metabolic stress (lactate [Lac]) and inflammation (interleukin-6 [IL-6]) were measured in 30 subjects who performed 6×10 back squat (BS), 3×10 bench press (BP), and 3×10 bent-over rows (BR) at 70% of 1-repetition maximum (1RM). The RMSSD, neuromuscular performance, and biomarkers were measured 10 min pre-exercise and 30 min post-exercise (Post30); HRV and Lac were also measured immediately post-exercise (Post0). Pre- versus post-exercise differences were evaluated using paired-samples t-tests. Pearson's correlations were used to determine the association between changes. With the exception of IL-6 (P=0.296) and MPVBP (P=0.678), LnRMSSD, neuromuscular performance, and metabolic stress were different post- compared to pre-exercise. We observed moderate associations between ΔLnRMSSD Post0 and ΔLac Post0 (r = -0.44) and ΔLac Post30 (r = -0.55), respectively. Practitioners should use multiple training load indicators to gain an accurate depiction of recovery.

African Americans have disproportionate levels of cardiovascular disease and oxidative stress. The purpose of our study was to examine racial differences between African American and Caucasian adults in time-course oxidative stress responses to a treadmill test. After a 12-hr fast, 18 participants (9 of each ethnic group; 21 ± 0.4 yrs) completed a submaximal treadmill test and underwent serial blood draws: Pre, Post (within 2 min), 30, 60, and 120 min after exercise. At each time-point, superoxide dismutase (SOD, U/mL), total antioxidant capacity (TAC, mM), protein carbonyls (PC, nmol/mg), and thiobarbituric acid-reactive substance (TBARs, μmol/L) were measured. We found no difference between groups for blood pressure, BMI, or exercise capacity (as measured by volume of oxygen consumed, VO(2) max). African Americans had significantly (p < 0.05) higher SOD (Pre: 5.45 ± 0.4 vs. 3.69 ± 0.69; 60 min: 8.99 ± 0.7 vs. 4.23 ± 0.6; 120 min: 9.69 ± 1.6 vs. 3.52 ± 0.7), TAC (Pre: 2.31 ± 0.25 vs. 1.16 ± 0.3; Post: 2.39 ± 0.2 vs. 1.34 ± 0.2; 30 min: 2.29 ± 0.2 vs. 1.09 ± 0.2), and PC (Pre: 1.09 ± 0.1 vs. 0.82 ± 0.1; Post: 1.14 ± 0.1 vs. 0.81 ± 0.1; 30 min: 1.13 ± 0.1 vs. 0.85 ± 0.1; 60 min: 1.06 ± 0.1 vs. 0.81 ± 0.05), but not TBARs. Between groups, only SOD exhibited a different time-course response: levels for African Americans rose steadily throughout the 120 min, while levels for Caucasians peaked at 30 min and by 120 min had returned to pre-exercise levels. Race had a greater effect on oxidative stress responses than submaximal exercise did. African Americans had significantly higher TAC, SOD, and PC levels compared to Caucasians.

The purpose of this study was to compare the accuracy of exercise energy expenditure (EXEE) measurements from a metabolic cart (HG_MC) to that obtained with a new exercise whole room indirect calorimeter (EX_WRIC). First, the HG_MC and the EX_WRIC were subjected to 10, 30-min ethanol (99.8% purity) and propane (99.5% purity) combustion validations, respectively, for EE, ventilation rates (liters) of oxygen (VO2), carbon dioxide (VCO2), and the respiratory quotient (RQ; VCO2/VO2). Then, 15 healthy adults (13 men and 2 women) cycled at 65% age predicted heart rate max for random determination of their EXEE, VO2, VCO2 and RQ after a 12-hr fast with both the HG-MC and EX_WRIC. Comparing stoichiometry to combustion, the HG_MC underestimated EE (P<0.05), VO2 (P<0.05), VCO2 (P<0.05), and RQ (P<0.05) while no differences were found for the EX_WRIC. The EXEE and VO2 were lower (P<0.05) while RQ was greater (P<0.05) when measured with the HG_MC versus the EX_WRIC. The EX_WRIC was more accurate than the HG_MC without the related tethered connections.

This study assessed the changes in time spent in moderate to vigorous physical activity (MVPA) on fat depots, insulin action, and inflammation. Longitudinal data were generated from 66 Hispanic adolescents (15.6±1.1 yr; BMI percentile 97.1±3.0) who participated in a 16-wk nutrition or nutrition+exercise intervention. There were no effects of the intervention on PA, but there were inter-individual changes in PA. For purposes of this analysis, all intervention groups were combined to assess how changes in PA during 16 wk affected changes in adiposity, insulin action, and markers of inflammation. MVPA was assessed by 7-day accelerometry, total body fat via DXA, liver fat by MRI, and insulin, glucose and HOMA-IR via a fasting blood draw. A repeated measures ANCOVA was used to assess the effect of MVPA on fat depots, insulin action, and inflammatory markers. Sixty-two percent of participants increased MVPA (mean increase, 19.7±16.5 min/day) and 38% decreased MVPA (mean decrease, 10.7±10.1 min/day). Those who increased MVPA by as little as 20 min per day over 16 wk, compared to those who decreased MVPA, had significant reductions in liver fat (-13% vs. +3%; P=0.01), leptin levels (-18% vs. +4%; P=0.02), and fasting insulin (-23% vs. +5%; P=0.05). These findings indicate that a modest increase in MVPA can improve metabolic health in sedentary overweight Hispanic adolescents.