PHYS30005 Lecture Notes - Lecture 1: Glycogenolysis, Fluid Balance, Acclimatization
Increasing environmental temp from 20 degrees to 40 degrees is associated with reduced exercise tolerance. 30 min time trial well-trained cyclists at 2 temps: 32c vs 23c, hotter environment, they reduced their power output. During isometric exercise at 2/3 of maximal voluntary contraction sustained for 2 mins. Marked reduction in the activation of the contracting muscles in the presence of hyperthermic: suggests that increased body temp is associated with reduced activation of muscle (major by-product of muscle contraction is heat) Increased cho use during exercise in the heat. Increased reliance on muscle glycogen with heat: associated with increased lactate production. Increase in muscle temp + increase circulating adrenalin -> increase glycogenolysis. Impacts: metabolism + muscle function, circulation + fluid balance, sweating -> lower co, lower. Sv -> influences ability of cardiovascular system to deliver oxygen to contracting muscles: cns + motor centres (recruitment and activation of muscles) Improved exercise tolerance in the heat with acclimatization.