Contribution of upper limb muscles to two different gripping styles in elite indoor tug of war athletes.

To investigate characteristic upper limb muscle use between two common tug of war (TOW) gripping styles, 20 elite athletes from two high school TOW teams were recruited. Under conditioned attack pulling (with 90% maximal force) on a tug machine, participants used their own habitual gripping style to pull for five 15-s trials. Force and kinematic measurements showed a significantly better force performance and higher centre-of-gravity tilting angle with the gripping style one than with the gripping style two (GS2) (both p < 0.05). However, an overall higher and more symmetrical muscle activation detected by normalised surface electromyography signal amplitude was found in the GS2 group (both p < 0.05). In both groups, the distal and flexor muscles were more activated than the proximal and extensor muscles, respectively (p < 0.05). Higher co-contraction ratio was found in the wrist joints of the latter arm in both groups (p < 0.05). As higher muscle activation level and co-contraction indicate higher muscle and joint injury incidences, we suggest that gripping style factors should be considered in training to prevent muscle and joint injury. Future study concerning segmental kinematics, ground reaction force, moment arm and muscle endurance during the defence phase are warranted.