Determinants of Physiological Resilience Among Recreational-To-Competitive Endurance Runners.

The aim of this study was to investigate (1) whether factors related to endurance performance are associated with physiological resilience in recreational-to-competitive runners, and (2) differences between recreational and competitive runners in physiological resilience. During three test days, 33 runners (15 competitive and 18 recreational) were tested for their peak fat oxidation, maximal blood lactate concentration (Lamax) after maximal anaerobic running test (MART), maximal voluntary contraction (MVC) in isometric leg press, maximal oxygen uptake (VO2max), maximal speed of incremental test (sPeak), speeds at ventilatory thresholds (sVTs), running economy (RE), and physiological resilience. Physiological resilience was tested as deterioration of VO2max, sPeak, VTs, and RE during and after ~2.5 h moderate-intensity run at ~90% of VT1. Associations between other variables and physiological resilience were analyzed using Pearson's or sex-adjusted partial correlations in the whole sample. Recreational runners had higher deterioration of VT1 (p = 0.049), but lower deterioration in RE (p = 0.042) than competitive runners. Lower decline in sPeak was associated with higher VO2max (r = 0.37, p = 0.04) and lower Lamax (r = -0.37, p = 0.03). Lower decline in sVT1 was associated with higher VO2max (r = 0.37, p = 0.04), sVT2 (r = 0.52, p = 0.002), sVT1 (r = 0.48, p = 0.006), and sPeak (r = 0.44, p = 0.01). Lower decline in RE was associated with worse RE (r = -0.49, p = 0.004) and higher MVC (r = -0.40, p = 0.02). Lower decline VO2max was associated with worse RE (r = 0.42, p = 0.02). It appears that physiological resilience is associated with multiple different physiological systems. High aerobic fitness and MVC of the leg extensors, and lower Lamax after MART may be related to better physiological resilience.