Leg and Forearm Muscle Power Changes Associated with Two Types of Underwater Exposure.

Abstract : Forearm muscle strength and leg muscle power were studied in 26 Explosive Ordnance Disposal (EOD) and 5 Special Warfare Swimmer Delivery Vehicle (SDV) divers. Control tests were done on non-driving days. An ischemic handgrip test measured developed force at a contraction rate of 1 per sec for a period of 60 sec. The Wingate anaerobic test measured leg muscle power during 30 sec of high intensity exercise on a bicycle ergometer. The results indicated that the EOD divers had a faster rate of body heat loss during their pool swim than did the SDV divers during their open water dives. Handgrip force was noticeably reduced in EOD divers post-dive, while no significant change was observed following SDV dives. The rate of forearm muscle fatigue was largely unaffected by either the pool swim or the cold water exposure. Peak leg muscle power was lower post-dive in the EOD group, but unchanged in the SDV group. This could be explained partially by the moderate leg exercise during the EOD swim, whereas the SDV divers had minimal leg exercise during their lives. The average leg power was reduced post-dive in both groups, suggesting that both dive exposures lessened the ability to sustain power. This study indicates that muscle performance is reduced after underwater exposures that mimic operational diving. The nature of the task performed during a dive in conjunction with water temperature, determines the extent to which muscle power or fatigue will be affected. Keywords: Hyperbarc exposures; Hypothermia; Muscle power; Human exercise testing; Immersion; Exercise.