Physiological and psychological recovery from muscle disruption following resistance exercise : the impact of chronic stress and strain
Stults, Matthew Alan
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A large body of evidence supports the notion that chronic stress and strain may impact healing from physical trauma. However, no evidence exists to substantiate whether chronic stress impacts recovery from exercise-induced muscle damage. In this study, a group of 31 undergraduate weight-training students completed the Perceived Stress Scale (PSS), Undergraduate Stress Survey (USQ, a measure of life event stress) a series of fitness tests and then returned 5 to 10 days later for an exhaustive resistance exercise stimulus (E-RES) workout. This workout was performed on a leg press to the cadence of a metronome to ensure a strong eccentric component of exercise. Participants were monitored for 1 hour after this workout and every day for 4 days afterwards. Hierarchical Linear Modeling (HLM) multi-level growth curve analyses demonstrated that stress measures were related to recovery from maximal resistance exercise for both functional muscular (maximal isometric force, jump height, and cycling power) and psychological (perceived energy, perceived fatigue, and soreness) outcomes. Stress was not related to outcomes immediately post-workout (except maximal cycling power) after controlling for pre-workout values. Thus, the effect of stress on recovery is not likely due to magnitude of disruption from maximal exercise. After controlling for significant covariates, including fitness and percent disruption from baseline, individuals scoring a 10 on the PSS at their first visit reached baseline 288% (2.88 times) faster than individuals who scored a 19 at this same time point. There were significant moderating effects of stress on affective responses during exercise. Feeling (pleasure/displeasure), activation (arousal), muscular pain and RPE (exertion) trajectories were moderated by stress. Exploratory analyses found that stress moderated physical recovery, but not psychological recovery in the first hour after the E-RES workout. Also, stress was related to the increase in IL-1[beta], a pro-inflammatory cytokine, in the 48 hour period after exercise for a sub-set of participants. These findings likely have important theoretical and clinical implications for those undergoing vigorous physical activity. Those experiencing chronic loads of stress and mental strain should include more rest time to ensure proper recovery.