Grip force (Table 4; Figs. 1, 2, 3)
Physical force performances were assessed with an electronic handgrip dynamometer (Fig. 1) by means of four tonic trials measuring the elapsed time from maximal grip strength (Fmax) to 50 % of Fmax (Table 4; Figs. 2, 3) and 10 phasic trials of F max, (Fig. 4). MANOVA was performed to compare mean physical strength performances during both phasic and tonic trials, fatiguability ratios (see below) and mean time to 50 % of F during tonic trials, between groups. Pillai's trace was significant for subject groups (F = 4.187, p = .007). Outcomes showed significant differences between groups for maximal mean grip strength during tonic and phasic conditions but not for mean time to 50 % of Fmax during tonic trials (Table 4). In addition, chronic fatigue patients showed higher fatiguability ratio during phasic trials (Phasic Fatiguability Ratio, PFR = (Phasic mean Fmax -Phasic Fmaxtrial 10)/Phasic mean Fmax) with a significantly different decline of Fmax, at the end or the phasic trials (Table 4; Fig. 4). Tonic trials did not show higher fatiguability in CFS patients (Tonic Fatiguability Ratio, TFR = (Tonic mean Fmax -Tonic Fmax trial 4)/Tonic mean Fmax) (Table 4). Repeated measures analyses (mixed ANOVA. Mauchly's test of sphericity. w = 0.720. p = NS) for time to 50% of Fmax during tonic trials did not show significant effects for trials x group. However, a main effect of Fmax during tonic trials was found for group (F = 5.805, p = 0.023). Mixed ANOVA for Fmax during phasic trials (signifinicant Mauchly's test of sphericity, w = 0.001, p < 0.001) showed (Greenhouse-Geisser corrections of F ratios were performed) significant effects for trials (F = 4.654, p = 0.007) and group (F = 9.748, p = 0.004) but not for trial x group.