AEROBIC ENERGY SUPPLY LIMITS HIGH-INTENSITY EXERCISE
Bishop, D., Bortolotti, S., & Ferri, A. (2009). Task failure during high-intensity exercise is associated with a critical reduction in tissue oxygenation. A paper presented at the 14th Annual Congress of the European College of Sport Science, Oslo, Norway, June 24-27.
This study assessed the hypothesis that task failure during high-intensity, whole-body exercise is associated with a critical reduction in tissue oxygenation. Well-trained cyclists (N = 6) performed an incremental test to exhaustion on a cycle ergometer. They then performed a familiarization session, followed by, in a random order, constant-load exercise tests at 100, 110, and 120% of VO2max until task failure. During these trials, monitoring of changes in the concentration of oxygenated haemoglobin and myoglobin (delta[02Hb]), deoxygenated Hb+Mb (delta [HHb]) in the right vastus lateralis, muscle and the frontal cerebral cortex occurred. Oxygen uptake (VO2) and rating of perceived exertion were also monitored.
At task failure, there was no significant difference between the three conditions for delta[HHb], delta[02Hb], oxygen uptake, or rating of perceived exertion. There were no significant differences between trials for cerebral oxygenation levels. Task failure during three different exercise intensities occurred at similar tissue oxygen (and oxygen consumption) levels.
Implication. Task failure during high-intensity exercise (at sea level) is associated with an inability to increase the rate of aerobic energy supply.
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