INTRODUCTION: Fundamental biomechanical parameters in trail running are step length (SL) and frequency (SR), contact (CT) and flight time (FT), and shock attenuation (SA) (Derrick et al., 1998). SA is considered a significant indicator for injury prevention (Mizrahi et al. 2000) and is influenced by several factors such as fatigue and foot strike pattern (Giandolini et al. 2014). The aim of the present study was to investigate the effect of fatigue on the kinematic parameters of step and SA during downhill trial running. METHODS: Eleven well trained participants (10 men and 2 women, age: 31.5±11.4 years, height: 173.9±5.6 cm, mass: 34.1±6.5 Kg) were enrolled. Four inertial sensors (EXLs3, 200 Hz) were attached to the pelvis, tibia, heel and second metatarsal head of the foot (Giandolini et al., 2014). Data were collected during a 290m downhill running (mean inclination 13°). The task was performed before and after an 18km trail running and filmed by a videocamera (Panasonic HC-V700, 50hz). The self-selected running speed was similar in both pre and post-trial acquisitions. 854 steps were analyzed. For each step, the following parameters were estimated SL, SR, step time (ST), CT, FT, SA, center of mass acceleration (CA), tibial acceleration (TA) and foot strike pattern (Giandolini et al. 2014). RESULTS: Reduced FT (p<0.009) and CA (p<0.047) were found comparing pre- and post- trial acquisitions. TA and FT (r=-0.664) and TA and SA (r=0.818) were found to be correlated. Considering foot strike pattern, forefoot strike decreased both TA and CA with respect to midfoot (p=0.013 and 0.013, respectively) and rearfoot strike (p=0.015 and 0.013, respectively). Comparing post- with respect to pre-trial acquisition, athletes used more the forefoot strike pattern (+7.38%). CONCLUSION: According to Mercer et al. (2002), the reduced SL, enhanced by a lower FT with similar SR and velocity, leaded to a lower TA. This result is confirmed by the negative correlation between FT and TA and by the positive correlation between TA and SA. Forefoot strike sustained the significant reduction of TA, according to DeWit et al. (2000). In the fatigued condition, the athletes tended to diminish FT and to use a forefoot strike pattern with the aim of reducing the impact of the tibia to the ground. References: De Wit B, De Clercq D, Aerts P. (2000). J Biomech, 33(3), 269-278. Derrick TR, Hamill J, Caldwell GE. (1998). Med Sci Sports Exerc, 30(1), 128-135. Giandolini M, Poupard T, Gimenez P, Horvais N, Millet GY, Morin JB, Samozino P. (2014). J Biomech, 47(7), 588-1593. Mercer JA, Vance J, Hreljac A, Hamill J. (2002). Eur J Appl Physiol, 87(4-5), 403-408. Mercer JA, Bates BT, Dufek JS, Hreljac A. (2003). J Sports Sci, 21(11), 911-919 Mizrahi J, Verbitsky O, Isakov E, Daily D. (2000). Hum Mov Sci, 19(2), 139-151.
FATIGUE EFFECT ON BIOMECHANICAL PARAMETERS OF TRAIL RUNNING.
CIACCI S.;TOTTI V.;BARTOLOMEI S.;NIGRO F.;FANTOZZI S.
2018
Abstract
INTRODUCTION: Fundamental biomechanical parameters in trail running are step length (SL) and frequency (SR), contact (CT) and flight time (FT), and shock attenuation (SA) (Derrick et al., 1998). SA is considered a significant indicator for injury prevention (Mizrahi et al. 2000) and is influenced by several factors such as fatigue and foot strike pattern (Giandolini et al. 2014). The aim of the present study was to investigate the effect of fatigue on the kinematic parameters of step and SA during downhill trial running. METHODS: Eleven well trained participants (10 men and 2 women, age: 31.5±11.4 years, height: 173.9±5.6 cm, mass: 34.1±6.5 Kg) were enrolled. Four inertial sensors (EXLs3, 200 Hz) were attached to the pelvis, tibia, heel and second metatarsal head of the foot (Giandolini et al., 2014). Data were collected during a 290m downhill running (mean inclination 13°). The task was performed before and after an 18km trail running and filmed by a videocamera (Panasonic HC-V700, 50hz). The self-selected running speed was similar in both pre and post-trial acquisitions. 854 steps were analyzed. For each step, the following parameters were estimated SL, SR, step time (ST), CT, FT, SA, center of mass acceleration (CA), tibial acceleration (TA) and foot strike pattern (Giandolini et al. 2014). RESULTS: Reduced FT (p<0.009) and CA (p<0.047) were found comparing pre- and post- trial acquisitions. TA and FT (r=-0.664) and TA and SA (r=0.818) were found to be correlated. Considering foot strike pattern, forefoot strike decreased both TA and CA with respect to midfoot (p=0.013 and 0.013, respectively) and rearfoot strike (p=0.015 and 0.013, respectively). Comparing post- with respect to pre-trial acquisition, athletes used more the forefoot strike pattern (+7.38%). CONCLUSION: According to Mercer et al. (2002), the reduced SL, enhanced by a lower FT with similar SR and velocity, leaded to a lower TA. This result is confirmed by the negative correlation between FT and TA and by the positive correlation between TA and SA. Forefoot strike sustained the significant reduction of TA, according to DeWit et al. (2000). In the fatigued condition, the athletes tended to diminish FT and to use a forefoot strike pattern with the aim of reducing the impact of the tibia to the ground. References: De Wit B, De Clercq D, Aerts P. (2000). J Biomech, 33(3), 269-278. Derrick TR, Hamill J, Caldwell GE. (1998). Med Sci Sports Exerc, 30(1), 128-135. Giandolini M, Poupard T, Gimenez P, Horvais N, Millet GY, Morin JB, Samozino P. (2014). J Biomech, 47(7), 588-1593. Mercer JA, Vance J, Hreljac A, Hamill J. (2002). Eur J Appl Physiol, 87(4-5), 403-408. Mercer JA, Bates BT, Dufek JS, Hreljac A. (2003). J Sports Sci, 21(11), 911-919 Mizrahi J, Verbitsky O, Isakov E, Daily D. (2000). Hum Mov Sci, 19(2), 139-151.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
