Figure 3

In order to normalise the conditioned H-reflexes in percent (%) for each participant, the unconditioned test H-reflex (not represented) was considered as the baseline. In all graphs, black boxplots/shapes represent the external (EF), the white ones the internal focus of attention (IF) and the grey ones the REST condition (no contraction and no focus). On the abscissa of (A) and (C), the early facilitation was adapted individually for each participant as the ISI that resulted in the first facilitation peak followed by an inhibition of the test H-reflex 1–2 ms later. (A) Shown are mean values and SEM (n = 14) of the peak-to-peak amplitudes of the conditioned H-reflexes at five different interstimulus intervals (ISIs : early facilitation, + 4, + 8, + 12 and + 16 ms) under both attentional strategies (EF and IF) in the right soleus muscle. On the abscissa, the ‘early facilitation’ was adapted individually for each participant as the ISI that resulted in the first facilitation peak followed by an inhibition of the test H-reflex 1–2 ms later. When comparing ISI curves, post hoc comparisons (see C for all interactions) showed that adopting an EF resulted in reduced conditioned H-reflexes at ISIs + 4, + 8 ms and + 16 ms, when compared with an IF. (B) Shown are individual values and boxplots of the of the peak-to-peak amplitudes of the conditioned H-reflexes comparing the three conditions (EF, IF and REST). The main effect of condition revealed that conditioned H-reflexes at REST were significantly smaller when compared with H-reflexes at EF and IF. *** P ≤ 0.001. (C) Shown are individual values (n = 14) and boxplots of the peak-to-peak amplitudes of the conditioned H-reflexes at five different interstimulus intervals (ISIs : early facilitation, + 4, + 8, + 12 and + 16 ms) under both attentional strategies (conditions: EF and IF) and the REST condition (no contraction and no specific focus of attention) in the right soleus muscle. When comparing the early facilitation, no significant difference was found between the conditions (EF, IF and REST). When comparing the ISI curves between the EF and IF condition, post hoc comparisons showed that adopting an EF resulted in reduced conditioned H-reflexes at ISIs + 4 (around − 16%) + 8 ms (around − 25%) and + 16 ms (around − 10%), when compared with an IF. The H-reflexes measured at the + 4 ms ISI were significantly smaller during the REST condition than the EF and or IF conditions. In order to normalise the conditioned H-reflexes in percent (%) for each participant, the unconditioned test H-reflex (not represented) was considered as the baseline.