Changes in physical performance over the intervention period. (A) Maximum running speed (mean ± standard deviation). P-values indicate differences from control group (post hoc Scheffé test). (B) Courses of submaximal exercise heart rate (means ± standard error). Letters (a-c) on x-axes indicate the final three steps preceding the transgression to the ramp-shaped phase of the exercise tests. Group × test × step interaction: P = 0.039.