787 Effects of Repeated Ultraendurance Cycling on Muscle Injury

Physiological Considerations of Ultraendurance Performance

“…In our recent ultraendurance cycling study (8,9,16,17,18,19,20,35,36,37,38), six professional cyclists (V0,max 83.4 rnl*kg-'min-') competed in two 4day stage-races (161 km-d-') on a computerized race simulator under controlled laboratory conditions (30°C, 60% relative humidity). Each 4-day stage-race was separated by an 18-day recovery period in which the athletes resumed normal training and race schedules.…”

“…Whether ultraendurance athletes have a greater capacity of gastric emptying and/or an increased capacity to provide carbohydrate during ultraendurance events remains unclear. However, ultradistance athletes have been reported to consume between 1-2 1.h-' of 5-10% carbohydratecontaining solutions that could potentially provide between 50-200 gm of carbohydrate per hour or 200-800 kcaloh-' (1,18,29). Additionally, ultradistance athletes typically consume various solid and semisolid foods throughout an event.…”

“…Therefore the highest serum enzyme levels have been reported in ultraendurance marathons and triathlons. Non-weight-bearing ultradistance events such as swimming or cycling have also been reported to increase serum enzyme activities, but to a lesser extent (18,53).…”

“…Although each of the aforementioned serum enzymes has been reported to increase following endurance or ultraendurance exercise (18,23,30,40), the origin of injury has been primarily attributed to significant muscle tissue trauma rather than cardiac or liver damage (53). Most authorities suggest that enzyme efflux is a result of myofibrillar damage and alterations in sarcolemmic structure precipitated by eccentric muscle contraction involved in weight-bearing exercise.…”