How does fatigue affect handstand balance? a non‑linear approach to study fatigue influence in handstand performance

Abstract

Background The handstand is an essential skill in acrobatic sports. This skill requires the athlete to maintain an inverted upright stance with only the hands supported, which requires a great effort of muscular coordination and motor control. Several factors influence the ability to control the posture, including fatigue, which is a bit studied constraint of handstand performance. Research question With the aim to find out whether variability in movement control can be an indicator of fatigue, the present study was carried out. Method Fourteen male acrobatic gymnasts were required to perform handstands. The time series for analyzing variability were capturing using Force Platforms, which is a traditional laboratory instrument, and Inertial Measurement Units (IMU), which is a more recent and less widely used, but more accessible tool. For this purpose, an analysis of the amount of variability was carried out, using the standard deviation. And analysis of the structure of variability (or complexity), using Detrended Fluctuation Analysis (DFA) and Fuzzy Entropy (FuEn). Results Our results reveal that fatigue causes significant increases in the amount of variability in the medio-lateral axis on the force platform, and in the IMU located in the area of the L5 vertebra. These changes are accompanied by increased auto-correlation in the medio-lateral axis of the force platform, and more unpredictable behavior in the L5 IMU. Key points • Amount of variability can discriminate between non-fatigued and fatigued states in force platform. • Structure of variability can discriminate between non-fatigued and fatigued states in force platform. • Movements are most affected in the medio-lateral axis. • Forces produced to maintain balance exhibit smoother adjustments in fatigue state. • Acceleration in the L5 tends to be less predictable in fatigue state.