(Key Laboratory of Ministry of Education,Beijing Sport University,Beijing 100084,China) Abstract: A continuous wavelet transform analysis was used for characterizing and manipulating the ground reaction whose statistics vary in time during the running stance phases and to investigate the neuromuscular tuning law by considering the lower limb stiffness and the activation degree of lower extremity muscles. 17 healthy males ran at forefoot (FFS), mid-foot (MFS) and rearfoot strikes using natural stride speed, and ground reaction forces and lower extremity muscle surface EMG were assessed during stance. The results showed that the maximum signal power (Pmax) and the sum of signal power are significantly higher in the stance of FFS than in MFS and RFS (P<0.05). In the early 20% of stance, the FFS exhibited a significantly less maximum pseudo-frequency (PFmax), and the PFmax also appeared significantly later. In addition, MFS exhibited significantly stiffer lower limb stiffness (P<0.05), while FFS had higher levels of lower extremity muscle activation in both. In conclusion, it is possible for runners to adjust the impact frequency by changing footstrike landing, FFS has a lower impact frequency and lower limb stiffness compared with MFS and RFS, which is not conducive to storage and utilization of lower limb elastic energy, and the higher level of lower extremity muscle activation easily led to fatigue. Keywords: sports biomechanics;running;wavelet transform;neuromuscular tuning law |