THE INFLUENCE OF HAND GUARDS ON FORCES AND MUSCLE-ACTIVITY DURING GIANT SWINGS ON THE HIGH BAR

To investigate the influence of hand guards on the loads experienced b y gymnasts during giant swings on the high bar, forces applied to the bar by each hand and muscle activity of the extrinsic finger flexor an d wrist extensor muscle groups were measured in 10 male gymnasts as th ey completed a minimum of three backward giant swings on the high bar. Measurements were made under four conditions of performance: bare han ds, 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 o f 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 bo th wrist flexor and extensor muscle activity was unchanged across cond itions. These results indicate that the use of hand guards allows grea ter tensile forces to act across the wrist without a measurable increa se in forearm muscle activity. Thus, it is possible that there is extr a 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.