Relationship between recovery of neuromuscular function and subsequent capacity to work above critical power

Purpose To investigate the relationship between the recovery of neuromuscular fatigue and the recovery of amount of work done above critical power ( W´ ). Methods Ten healthy men performed, on different days, constant work rate exercises until task failure to determine critical power (CP) and W´ . In the three following visits, participants performed two exhausting constant work rate exercises estimated to induce task failure within 6 min (P6 1 and P6 2 ), interspaced by 3, 6 or 15 min of recovery. Neuromuscular function was assessed before and periodically after the P6 1 using percutaneous electrical femoral nerve stimulation. The W ´ recovery was measured from the total work performed above CP during the P6 2 . Results The P6 1 induced a full use of W´ and a reduction in maximal voluntary contraction (MVC, − 19 ± 4%), voluntary activation (VA, − 6 ± 2%) and twitch force stimulated at 1 Hz (− 37 ± 11%), 10 Hz (− 50 ± 16%) and 100 Hz (− 32 ± 11%), when compared to baseline ( P < 0.05). The time constant of VA recovery was significantly faster than the time constant of W ´ recovery ( P < 0.05), but there was no significant difference between the time constant of W ´ recovery and the time constant of recovery of MVC or twitch force stimulated at 1, 10 and 100 Hz ( P > 0.05). However, the time constant of W ´ recovery was only associated to the time constant of MVC recovery ( r = 0.73, P < 0.05). Conclusion The W ´ recovery is not associated to the recovery of peripheral or central fatigue alone. Rather, W ´ seems to be associated to the recovery of the overall capacity to generate force.