OL training is associated with a reduction and greater daily fluctuation in vagal activity compared with BL, concurrent with decrements in perceived fatigue and muscle soreness. These effects are reversed during TP where these values returned to baseline or peaked leading into successful competition. The strong inverse relationship between average vagal activity and its daily fluctuation weakened during TP.

Purpose: The purpose of the study was to compare a single two-dimensional image processing system (IMAGE) to underwater weighing (UWW) for measuring body volume (BV) and subsequently estimating body fat percentage (%Fat), fat mass (FM), and fat-free mass (FFM) via a 3-compartment (3C) model. Methods: A sample of participants age 18-39 yr was recruited for this study (n = 67, 47.8% female). BV was measured with UWW and predicted via the IMAGE software. The BV estimates from UWW (3C UWW ) and IMAGE (3C IMAGE ) were separately combined with constant total body water and body mass values for 3C model calculation of %Fat, FM, and FFM. Results: BV obtained from the IMAGE was 67.76 ± 12.19 and 67.72 ± 12.04 L from UWW, which was not significantly different (P = 0.578) and very largely correlated (r = 0.99, P < 0.001). When converted to %Fat (3C UWW = 21.01% ± 7.30%, 3C IMAGE = 21.08% ± 7.04%, P = 0.775), FM (3C UWW = 14.68 ± 5.15 kg, 3C IMAGE = 14.78 ± 5.08 kg, P = 0.578), and FFM (3C UWW = 57.00 ± 13.20 kg, 3C IMAGE = 56.90 ± 12.84 kg, P = 0.578) with the 3C model, no significant mean differences and very large correlations (r values ranged from 0.96 to 0.99) were observed. In addition, the standard error of estimate, total error, and 95% limits of agreement for all three metrics were small and considered acceptable. Conclusions: An IMAGE system provides valid estimates of BV that accurately estimates body composition in a 3C model.

Background Research comparing bioimpedance spectroscopy (BIS) to dual-energy X-ray absorptiometry (DXA) is limited, especially with newer BIS devices that take measures in a standing position instead of the traditional supine position.Purpose The purpose of this study was to compare a standing BIS device (BIS STA ) and a supine BIS device (BIS SUP ) to DXA for measuring body fat percentage (BF%), fat mass (FM) and fat-free mass (FFM) in a cohort of male and female subjects displaying a wide range of ages and BMI levels. Methods Ninety-five subjects (30 AE 15 years, 170 AE 8Á0 cm, 72Á6 AE 14Á8 kg) participated in the study. Body composition measures were taken from BIS STA , BIS SUP and DXA during a single visit to the laboratory following an 8-to 12-h fast in a euhydration state. Results Supine BIS device and BIS STA produced r-values >0Á91 and low SEE values for all measurements compared to DXA. Effect sizes were 'trivial' for FFM comparing both BIS SUP and BIS STA to DXA (<0Á1) and 'small' for FM and BF% (<0Á39). Compared to DXA, BIS STA resulted in lower total (TE) and constant errors/mean differences (CE) (TE < 3Á6 kg, CE < À1Á82 kg) versus BIS SUP (TE < 4Á35 kg, CE < À3Á10 kg) for FFM. Conclusion Fat-free mass values for BIS STA resulted in the most comparable measurements to DXA with no mean differences and the lowest total error and effect size. However, the findings indicated both BIS devices may be acceptable alternatives to DXA for BF%, FM and FFM in clinical practice. BIS STA -DXA (FFM kg) BIS STA -DXA (FFM kg) BIS STA -DXA (FM kg) BIS STA -DXA (FM kg) BIS SUP -DXA (FFM kg) BIS SUP -DXA (FFM kg) BIS SUP -DXA (FM kg) BIS SUP -DXA (FM kg) BIS STA -DXA (BF%) BIS STA -DXA (BF%) BIS SUP -DXA (BF%) BIS SUP -DXA (BF%) Standing BIS (BIS STA ) v DXA Supine BIS (BIS SUP ) v DXA Figure 1 Bland-Altman plots comparing the standing (BIS STA ) and supine (BIS SUP ) bioimpedance devices to dual-energy X-ray absorptiometry (DXA) for fat-free mass (FFM), fat mass (FM) and body fat percentage (BF%). The solid line represents the constant error, the outside dashed lines represent the 95% limits of agreement and the dashed-dotted regression line represents the trend between the x-and y-axes.

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PurposeThis study aimed to describe maximal and submaximal cardiorespiratory fitness from early adulthood to midlife and examine differences in maximal fitness at age 20 yr and changes in fitness overtime by subcategories of sociodemographic, behavioral, and health-related factors.MethodsData include 5018 Coronary Artery Risk Development in Young Adults participants (mean (SD) age, 24.8 (3.7) yr; 53.3% female; and 51.4% Black participants) who completed at least one maximal graded exercise test at baseline and/or the year 7 and 20 exams. Maximal and submaximal fitness were estimated by exercise duration and heart rate at the end of stage 2. Multivariable adjusted linear-mixed models were used to estimate fitness trajectories using age as the mechanism for time after adjustment for covariates. Fitness trajectories from ages 20 to 50 yr in 5-yr increments were estimated overall and by subgroups determined by each factor after adjustment for duration within the less favorable category.ResultsMean (95% confidence interval) maximal fitness at age 20 and 50 yr was 613 (607–616) and 357 (350–362) s; submaximal heart rate during this period also reflected age-related fitness declines (126 (125–127) and 138 (137–138) bpm). Compared with men, women had lower maximal fitness at age 20 yr (P < 0.001), which persisted over follow-up (P < 0.001); differences were also found by race within sex strata (all P < 0.001). Differences in maximal fitness at age 20 yr were noted by socioeconomic, behavioral, and health-related status in young adulthood (all P < 0.05), which persisted over follow-up (all P < 0.001) and were generally consistent in sex-stratified analyses.ConclusionsTargeting individuals experiencing accelerated fitness declines with tailored intervention strategies may provide an opportunity to preserve fitness throughout midlife to reduce lifetime cardiovascular disease risk.