The influence of hand guards on forces and muscle activity during giant swings on the high bar

Abstract

To investigate the influence of hand guards on the loads experienced by gymnasts during giant swings on the high bar, forces applied to the bar by each hand and muscle activity of the extrinsic finger flexor and wrist extensor muscle groups were measured in 10 male gymnasts as they completed a minimum of three backward giant swings on the high bar. Measurements were made under four conditions of performance: bare hands, with webbing loops, with doweled hand guards (DHG), and a wind-up swing using DHG. Peak reaction forces at the hands were of the order of 2.2 times body weight (BW) on each hand, and were significantly (P < 0.05) lower when swinging bare-handed, compared with the other three conditions. By contrast, the integrated electromyograms showed that both wrist flexor and extensor muscle activity was unchanged across conditions. These results indicate that the use of hand guards allows greater tensile forces to act across the wrist without a measureable increase in forearm muscle activity. Thus, it is possible that there is extra stress on the ligaments of the wrist or at the epiphyseal plates. In adolescent and preadolescent gymnasts, the additional tension on the distal epiphyses of the radius and ulna may have implications for bone growth.