Painfulness of the stimulus.

To evaluate the painfulness of DOMS all subjects rated the pain perceived during contraction or physical stimulation. Subjects contracted the thigh repeatedly during 5 cycles of 24 seconds each or the respective muscle was stimulated with the heavy marble rolling pin by the experimenter (compare protocol in Fig. 1). Individual pain-ratings (VAS-scale) are given as averages across the 5 cycles (grey lines) and as common average (black circles) across the group. On average the subjects rated the painfulness of (a) the voluntary contraction to 35±14 % and (b) the physical stimulation as 50±8 % on the VAS scale. Thus, physical stimulation was judged as more painful (n = 8 each; p = 0.02 Mann-Whitney U-test; error bars show S.E.M.; grey areas indicate averaged highs and lows). Subjects had no resting pain and experienced pain only during stimulation of the affected limb and not of the control side.