Neuromuscular and electromechanical properties of ultra-power athletes: the traceurs

Practising a power-type activity over years can shape the neuromuscular profile of athletes. This study aimed at comparing the neuromuscular profile of a non-trained group (NT, n = 10) to power athletes practising Parkour (= traceurs, group PK, n = 11), an activity consisting of jumping obstacles mostly in an urban landscape. Maximal isometric plantar flexion force (MVC) and rate of torque development (RTD) were evaluated, and neuromuscular function of triceps surae muscles was assessed and compared between groups through the analysis of evoked potentials from posterior tibial nerve stimulation. PK group exhibited higher MVC force (131.3 +/- 8.7 Nm) than NT (110.4 +/- 9.6 Nm, P = 0.03) and higher RTD (489.1 +/- 93 Nm/s) than NT (296.9 +/- 81 Nm/s). At a nervous level, this greater performance was related to a greater voluntary activation level (PK: 96.8 +/- 3.6%; NT: 91.5 +/- 7.7%; P = 0.02) and soleus V-wave amplitude (P = 0.03), and a lower antagonist co-activation (P = 0.02) and rest soleus spinal excitability (PK H (max)/M (max): 0.32 +/- 0.13; NT: 0.58 +/- 0.17; P < 0.001). At a muscular level, PK group exhibited higher mechanical twitch amplitude (PK: 13.42 +/- 3.52 Nm; NT: 9.86 +/- 4.38 Nm; P = 0.03) and electromechanical efficiency (P = 0.04). The greater maximal force production capacity of traceurs compared to untrained was underlain by nervous factors, such as greater descending command and greater ability to modulate the spinal excitability, but also by muscular factors such as greater excitation-contraction coupling efficiency. The high eccentric loads that characterize Parkour training may have led traceurs to exhibit such neuromuscular profile.