RECOVERY AND FATIGABILITY FOLLOWING MAXIMAL AND SUBMAXIMAL EXERCISE
Authors: Wooten Liana C. , Aldhahi Monira I. , Murray Donal , Chin Lisa MK. , Keyser Randall E. 
Published: June 2021

Measures of cardiorespiratory function during recovery from an exercise challenge may provide insight into the capacity to perform subsequent bouts of activity. However, the relationship between recovery of cardiorespiratory homeostasis and fatigability during subsequent bouts of activity is not well understood.PurposeTo characterize oxygen consumption (VO2off) kinetics during the recovery following maximal and submaximal exercise and examine the relationship between VO2off kinetics and fatigability during a subsequent bout of submaximal activity.Methods6 healthy subjects (2 male, 4 female; 31.8±4.6 years) completed a maximal cardiopulmonary exercise test followed by a 10‐minute walk test (10‐MW). On a separate day, a submaximal constant work rate test was followed by a 10‐MW. Indices of VO2off kinetics, including the off‐kinetics transition constant (KtO), mean response time (MRT), time constant (τ), VO2 amplitude change (Δamp), and Δamp half‐time (t1/2) were determined. Performance (PF) and perceived (PC) fatigability were scored during each 10‐MW as change in walking speed and change in self‐rated fatigue severity, each normalized the individuals' distance walked. Higher PF and PC scores indicate greater presence of fatigability. Data were analyzed using paired samples t‐test and Pearson's correlation coefficient (r).ResultsMean values of KtO were greater (p<.001) following maximal vs. submaximal exercise (−43.6±18.4 mL/min/s vs. −24.2±17.4 mL/min/s, respectively). No difference was observed for fatigability scores during the 10MW between maximal and submaximal exercise (PF: 0.97±0.15, 1.0±0.09; PC: 3.8±1.5, 3.56±0.88). Following maximal exercise, PF was directly correlated with KtO (r=0.68) and Δamp (r=0.68), while PC was directly correlated with τ (r=0.74). Following submaximal exercise, PF was directly correlated with τ (r=0.76), t1/2 (r=0.91), Δamp (r=0.55), and KtO (r=0.52). PC following submaximal exercise was indirectly correlated with all indices of VO2 off‐kinetics including Δamp (r=−0.60), τ (r=−0.62), t1/2 (r=−0.84), MRT (r=−0.81), and KtO (r=−0.62).ConclusionDespite a greater VO2 amplitude change during maximal compared to moderate exercise, indices of VO2off kinetics suggested an efficient recovery in this sample of healthy individuals, in that neither intensity effected performance nor perceived fatigability. PF scores were directly associated with VO2off kinetics indices following both maximal and submaximal exercise, while PC scores were directly associated with VO2off kinetics only after maximal exercise. Findings of this pilot study may suggest that performance fatigability could reflect the recovery rate of the oxidative metabolic system following cessation of both severe and moderate intensity activity. Results of this study must be delimited to the current sample and cannot be generalized to the population at large.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.