Abstract:

Objectives: To observe neuromuscular and mechanical changes of lower limbs in football players during repeated sprint test . Methods: 10 professional football players participated in this study, performing repeated 6 × 35 m sprint with 10s intervals. The players wore their football shoes and received the test on an artificial turf. The mechanics of lower limbs and surface electromyography (sEMG) RMS of vastus lateralis (VL), rectus femoris (RF), and biceps femoris (BF) were tested by plantar pressure system and sEMG equipment respectively. And the blood lactate, heart rate, and rate of perceived effort (RPE) after 6 repeated sprints were measured too. Results: blood lactate, heart rate, RPE, and fatigue index was 11.2 ± 2.2 mmol/L, 170.6 ± 5.3 beats/min, 16.5 ± 1.2, and 38.4 ± 4.6 % respectively after 6 repeated sprints. Kinematic data indicated that sprint time and contact time in the final sprint increased by 28.2% and 10.7%(P<0.05 as compared to the first sprint. However, the flight time presented no significant change. The stride frequency and vertical stiffness of lower limbs declined by -8.4%(P<0.05)and -33.1% (P<0.01). The RMS of RF, BF, and VL declined by -12.3%(P<0.01), -19.6%(P<0.01),and -7.1%(P>0.05)respectively. The RMS of RF and BF and sprint time presented significant negative relationship (r=-0.89 and r=-0.98, P<0.05). Conclusion: repeated anaerobic sprint leads to substantial change of stride mechanics and neuromuscular control abilities. The results also confirm the relationship between repeated anaerobic sprint abilities and neuromuscular activation level.

Key words: football, repeated sprint, mechanics, electromyography, fatigue, test