Physiological responses to load holding and load carriage

Abstract
Seven young healthy men held and carried loads of 15, 20, 25, 30 and 40 kg to exhaustion in a total of 280 tests. The mean maximum time .**GRAPHIC**. for load holding was hyperbolically related to the mass of the load. The .**GRAPHIC**. for load carrying was shorter than for load holding, and the hyperbolic relationships for both load holding and load carrying were of a form similar to those found for segmental isometric contractions. Heart rate increases (.DELTA.HR) at exhaustion were linearly related to the load and .DELTA.HR was, for every load, greater when the load was carried rather than simply held. Electromyographic activity in the forearm flexor muscles increased when the load was carried and appeared in the form of marked fluctuations synchronous with the stepping frequency.