Neuromuscular characteristics and fatigue during 10 km running

This study investigated neuromuscular characteristics and fatigue during 10 km running (10 K) performance in well-trained endurance athletes with diff erent distance running capability. Nine high (HC) and ten low (LC) caliber endurance athletes performed the 10 K on a 200 m indoor track, constant vel ocity lap (CVL, 4.5 m x s(-1)) 5 times during the course of the 10 K and ma ximal 20 m speed test before (20 mb) and after (20 in,) the 10 K. Running v elocity (V), ground contact times (CT), ground reaction forces (F) and elec tromyographic activity (EMG) of the leg muscles (vastus lateralis; VL, bice ps femoris: BF, gastrocnemius; GA) were measured during 20 mb, 20 m,, and C VLs, The 10 K times differed (p < 0.001) between HC and LC (36.3 +/- 1.2 an d 39.2 +/- 2.0 min, respectively) but; no differences were observed in 20 m b velocity. The 10 K led to significant (p < 0.05) decreases in V, F and in tegrated EMG (IEMG) and increases in CTs of 20 m, in both groups. Mo change s were observed in Hf or LC in F and IEMG during the CVLs but HC showed sho rter (p < 0.05) mean CT of CVLs than LC, A significant correlation (r = -0. 56, p < 0.05) was observed between the mean CT of CVLs and velocity of 10 K (V-10K). Pre-activity of GA in relation to the IEMG of the total contact p hase during the CVLs was higher (p < 0.05) in HC than LC. The relative IEMG s of VL and GA in the propulsion phase compared to the IEMG of the 20 mb we re lower (p < 0.05) in HC than LC, In conclusion, marked fatigue took place in both HC and LC during the 10 K but the fatigue-induced changes in maxim al 20 m run did not differentiate endurance athletes with different V-10K. However, a capability to produce force rapidly throughout the 10 K accompan ied with optimal preactivation and contact phase activation seem to be impo rtant for 10 km running performance in well trained endurance athletes.