This randomized, double-blinded, placebo-controlled study aimed to investigate the effect of strength training (ST) combined with vitamin C and E supplementation on perceived and performance fatigability in breast cancer survivors (BCS). Twenty-five BCS were randomly assigned to one of two groups: vitamins (VIT; n = 12; 51.0 ± 9.0 years); or placebo (PLA; n = 13; 48.2 ± 8.3 years). Both groups performed a 10-week ST protocol, twice a week. VIT was supplemented with vitamins C (500mg/day) and E (180mg/day) and PLA with polydextrose (1g/day), once a day after breakfast. At the beginning and at the end of training period, perceived fatigability was assessed using MFI-20 (general fatigue and physical fatigue). Performance fatigability was assessed during 30 maximal isokinetic knee extension at 120º/s-1. General fatigue reduced similarly in VIT (p = 0.004) and PLA (p = 0.011). Physical fatigue reduced similarly in both, VIT (p = 0.011) and PLA (p = 0.001). Performance fatigability also decreased similarly in VIT (p = 0.026) and PLA (p < 0.001). There was no difference between groups in any moment (p > 0.05). In summary, antioxidants supplementation does not add any positive synergistic effect to ST on improving perceived or performance fatigability in BCS. Novelty: -Strength training with maximal repetitions reduces perceived and performance fatigability of BCS. -Vitamins C and E supplementation does no add any positive synergistic effect to ST on reducing fatigability in BCS.
Measuring ankle torque is of paramount importance. This study compared the test–retest reliability of the plantar flexion torque–generating capacity between older and younger men. Twenty-one older (68 ± 6 years) and 22 younger (25 ± 5 years) men were tested twice for maximal isometric plantar flexion. Peak torque (PT), rate of torque development, and contractile impulses (CI) were obtained from 0 to 50 ms (rate of torque development0–50; CI0–50) and from 100 to 200 ms (rate of torque development100–200; CI100–200). Typical error as the coefficient of variation (CVTE) and intraclass correlation coefficient were used to assess test–retest reliability. Student’s t test was applied to investigate systematic errors. The CVTE ratio was used for between-group comparisons. Only PT demonstrated acceptable reliability (intraclass correlation coefficient ≥ .75 and CV ≤ 10%). Older men demonstrated greater CVTE than younger men for PT (ratio = 2.24), but lesser for rapid torque (ratio ≤ 0.84). Younger men demonstrated systematic error for PT (6.5%) and CI100–200 (−8.9%). In conclusion, older men demonstrated greater variability for maximal torque output, but lesser for rapid torque.
Aging is associated with neurodegeneration and a loss of muscle function, especially in lower-limb muscles. While caffeine may augment muscle force generation through multiple effects on the central nervous system, no studies have yet compared the effects of caffeine on force-generating capacity between younger and older men, who might respond differently due to age-related changes in the structures on which caffeine acts. In a double-blind, controlled trial, 22 younger (25 ± 5 years) and 21 older (68 ± 6 years) men were tested for isometric plantarflexor torque on two separate days (2–7 days apart) before and 60 min after ingesting 3 mg/kg (∼2 cups of coffee) of caffeine or placebo. No effects of caffeine ingestion on peak torque or rate of torque development were detected in either older or younger men. Therefore, 3 mg/kg of caffeine may not acutely counteract age-related decreases in force capacity of the functionally important plantarflexor muscles.
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