Relationship between postural control and muscle activity during a handstand in young and adult gymnasts.

The aim of this study was to evaluate the relationship between muscle activity and inter-muscle contributions patterns and postural control during a handstand. Additionally, outcomes were compared between young and adult gymnasts (mean ± SD: 13.9 ± 0.7 and 23 ± 3 years respectively). Participants performed three trials of a 10 s handstand on a force platform with simultaneous EMG signal recording at the upper and lower limbs. Adult gymnasts demonstrated significantly better postural control in each studied variable. The wrist flexors demonstrated the highest relative mean (60%) and peak (200%) EMG activity of all muscle groups studied. Wrist flexor activity was also highly correlated with postural control variables in both groups. The trapezius descendens and wrist flexor muscles demonstrated the highest contribution (20-26% and 25.5-28% respectively), followed by anterior deltoid (15-18%) and triceps brachii (13-16%) in both groups. The young gymnast group demonstrated significantly greater mean relative muscle activity at the triceps brachii, biceps brachii and rectus femoris compared with the adult group (88% (p = 0.023), 150% (p = 0.003) and 75% (p = 0.039) respectively). To conclude, despite comparable inter-muscle contributions during a handstand, young and adult gymnasts demonstrated a different relationship between muscle activity and postural control variables.