In boxing, an efficient punch requires a combination of force, velocity and stability of the athlete. Being able to monitor these parameters has the potential to better inform training practices required to reach high performance. Hence, the aim of this study was to investigate the differences in punching execution between two groups of elite boxers (senior vs. junior) using three biomechanical indicators of performance in boxing. Each athlete was equipped with an instrumented suit composed of 17 inertial measurement units (IMU) and were asked to perform several series of punches with 3 standardized punching techniques (cross, hook and uppercut) on a punching bag with maximal force. Linear velocity, stability and punch forces were computed from the different sensors. Our findings show that senior boxers systematically produced more force and at a higher velocity for the three punching techniques compared to juniors. The IMU analysis also reveals differences of joint contributions between seniors and juniors, juniors presenting a higher contribution of the shoulder for the three punching techniques.

(2019). Difference of stability between two elite boxing groups: a preliminary study. Computer Methods in Biomechanics and Biomedical Engineering: Vol. 22, 44th Congress of the Société de Biomécanique, pp. S481-S483.

The purpose of this study was to validate a new motion analysis system which uses the technology of inertial sensors (Moven system). This innovative system is composed of 17 miniature inertial sensors attached to the body. The validation procedure consisted in comparing the data of the right hand trajectory collected by the Moven system with those given by an optoelectronic system (Vicon) composed of 6 infrared camcorders. The comparison of kinematic data was performed during a shot put training session in three high level athletes. The results of this preliminary study only concern the velocity module of the hand (on the middle of the second metacarpal) during the shot put. Paired ttest, r correlation coefficient and Bland & Altman test were used to compare the validity and the limit of agreement between the two tools. The results showed no difference between the measurements (p = 0.066). The correlation between the tools’ measurements is r > 0.46. Bland & Altman test showed low reliability (bias < 0.15 más-1) and accuracy (mean error = 0.63 más-1) between tools. Similar patterns of the right hand velocity curves during the shot put were obtained with both devices. However, they were differences in velocity intensity for some phases of the throw. The differences in sampling frequency and computational algorithms employed by the Moven and Vicon systems could partly explain these differences in shot-put velocity.

The maximal total power (P_max) is one of the major determinants of sprint performance. It can be calculated using a simple model based on the runner’s velocity. This velocity has already been measured with force plates, video cameras or a radar system, but not with an inertial system. The purpose of this study was to compare P_max measured with a radar system and with a multiple inertial sensors system. Seven participants (174.0 ± 6.9 cm; 67.7 ± 10.1 kg; 22.3 ± 1.7 years) realized two maximal 40-m sprints. Each athlete was equipped with an instrumented suit composed of 17 inertial measurement units (IMU) (Xsens), and a radar (Stalker ATS) was placed behind them. Both systems measured the athletes’ instantaneous horizontal velocity during the acceleration phase. Using an exponential model, P_max, maximal velocity (V_max), the slope of the exponential model (τ), maximal force (F₀) and the slope of the force, the velocity relationship (SFV) was calculated. The results showed that P_max, V_max, τ, F₀ and SFV were not significantly different between the radar and the Xsens system (p > 0.13). P_max, V_max and F₀ measured with the radar were correlated with the same parameters measured with Xsens (r > 0.81 and p ≤ 0.03). The IMU system can be accurately used to measure the main parameters that determine the sprint running performance: P_max, V_max and F₀. Moreover, contrary to the radar system, multiple inertial sensors will allow for an understanding of the role of the segments in maximal sprint running.

In order to better inform the effects of dehydration and hydration guidelines, we tested the acute effects of a 2% dehydration protocol on performance and technique of 3-point shooting (3PS) in Elite Basketball players (n = 9). The 3PS technique was monitored by using nanotechnology inertial measurement units positioned onto body joints during the exercise. When dehydrated (−2.1 ± 0.5% of body mass), 7 players experienced a slight decrease (−10.0 ± 19.6%, p = 0.16) in success rate, while RPE increased from 9.1 ± 2.6 to 13.0 ± 2.5 in euhydrated (EUH) and dehydrated (DEH) condition respectively (p = 0.003). DEH slightly altered the 3PS technique as the knee angle increased (p = 0.02) at toe-off time and the hip angle decreased during the 3PS (p = 0.01). The speed of ball release tended to be increased (p = 0.05) in DEH compared to EUH. Data from this study suggest that a 2% dehydration is tolerable for elite Basketball players, although a stronger dehydration might accentuate the effects observed.