2020, Volume 16
The carried military load increases the impulse and time of a front kick but reduces the peak velocity of the knee, hip, and shoulder of the kicking leg
Michal Vagner1, Petr Stastny2, Petr Kubovy1, Vladimir Hojka1, Jan Malecek1
1Charles University, Faculty of Physical Education, Prague, Czech Republic
2Department of sport games, Charles University, Faculty of Physical Education, Prague, Czech Republic
Author for correspondence: Michal Vagner; Charles University, Faculty of Physical Education, Prague, Czech Republic; email: firstname.lastname@example.org
Background and Study Aim: Wearing of protective equipment and a backpack is a crucial factor that influences velocity and dynamic forces during the front kick, which is largely described in unloaded conditions. Therefore, the aim of this study was the knowledge about the effects of wearing a ballistic vest and backpack on the peak velocity and dynamic forces during the front kick.
Material and Methods: Twenty-five male soldiers (27.7 ±7.2 yr, 83.8 ±6.1 kg, 180.5 ±6.5 cm) performed six individual front kicks with no carried load (NL) and with 30-kg loads composed of military equipment (WL) (boots and rifle = 3 kg, ballistic vest =12 kg and backpack = 15 kg). The 3D kinematics and kinetics were used to estimate the kick velocity and dynamic forces of the front kicks. Peak force (N), impulse (N·s), time to reach peak force (s), time of the kick (s) and peak velocity of the foot (PFV), knee (PKV), hip (PHV) and shoulder (PSV) of the kick (m·s-1) were measured. Data were analyzed using the ICC, Wilcoxon paired test or paired sample t-tests, correlation coefficient and Cohen’s d. The alpha level of significance was p<0.05.
Results: Significant differences were found between the NL and WL conditions in PHV (p = 0.001; d = 0.79) and PSV (p<0.001; d = 0.60), impact (p = 0.045; d = 0.49) and time of the kick (p = 0.046, d = 0.23, respectively). The NL condition produces higher PHV and PSV and lower impact force and time of the kick.
Conclusions: The 30-kg carried load reduces PHV and PSV and dynamic forces during the front kick. Therefore, individuals who execute a front kick while wearing a load of more than 30 kg should focus on strengthening the muscles associated with maintaining postural stability.
Key words: Reaction forces, impact, dynamic, kinematic, self defense, close combat, personal protective equipment, military back pack