Breaking-Up Sedentary Behavior and Detraining Effects on Glycemic Control: A Randomized Crossover Trial in Trained Older Adults.

In a randomized crossover trial, we examined the effects of interrupting sedentary behavior on glycemic control in trained older adults, before and after 2 weeks of detraining. Fourteen participants (65-90 years old) completed two 7-hr conditions before and after 2 weeks of detraining: (a) uninterrupted sitting (SIT) and (b) sitting plus 2 min of moderate-intensity activity every 30 min (INT). Both before and after detraining, no differences were observed for 7-hr glucose area under the curve (7 hr AUC) and mean glucose between sitting plus 2 min of moderate-intensity activity and uninterrupted sitting conditions. After detraining and for the SIT condition, higher values of 7-hr AUC (p = .014) and mean glucose (p = .015) were observed, indicating worsened glycemic control. No changes were observed in INT condition between both time points. Frequent interruptions in sedentary behavior had no effect on glycemic control, prior to or after detraining. Even so, older adults experiencing a short-term detraining period should avoid prolonged bouts of sedentary behavior that may jeopardize their glycemic control.

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

BACKGROUND: 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. PURPOSE: To determine the effects of a 2-week detraining period on PhA and muscular strength (MS) in trained older adults. METHODS: A total of 14 trained older adults (6 females) aged ≥65 years (77.2 ± 6.6) were assessed at baseline (i.e. trained condition) and after 2 weeks 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, 50 kHz ± 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. RESULTS: 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. CONCLUSION: 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.