The impact of 2weeks of detraining on phase angle, BIVA patterns, and muscle strength in trained older adults.

Abstract

An intermission in the training routine, in which older adults refrain from regular structured exercise, may have deleterious effects on muscle performance and bioelectric phase angle (PhA), which is a predictive marker for cellular integrity. To determine the effects of a 2-week detraining period on PhA and muscular strength (MS) in trained older adults. A total of 14 trained older adults (6 females) aged ≥65years (77.2±6.6) were assessed at baseline (i.e. trained condition) and after 2weeks of detraining, where they refrained from their usual participation in structured exercise sessions. Whole-body resistance (R), reactance (Xc), and PhA were assessed using bioelectrical impedance analysis (BIA, single frequency, 50kHz±1%, NutriLab, Akern). MS was assessed on both lower and upper limbs under isometric conditions. Differences between moments were examined using ANOVA for repeated measures, while adjusting for sex. Bioimpedance vector analysis (BIVA) was performed to evaluate changes in cellular function and body fluid content. Detraining resulted in declines in PhA (-4.34%) (p=0.017). There was a significant difference in the mean impedance vectors from baseline to post-detraining (p<0.05), which were driven by decreases in reactance (Xc) relative to height (Xc/H) with little change in resistance (R) relative to height (R/H) for both males and females. No differences were found in MS for both the leg press (p=0.992) and bench press (p=0.166) tests. A detraining period as short as 2-weeks is enough to cause alterations in the bodies bioelectrical properties, resulting in detrimental changes in PhA, due to alterations in cellular integrity, but not in MS. These results highlight the importance of maintaining structured exercise sessions in older adults, and reinforce the potential role of PhA as a sensitive predictor to detect acute changes in muscle cell integrity following alterations in exercise training.