Accumulated O₂ Deficit during Intense Exercise and Muscle Characteristics of Elite Athletes

Abstract

The accumulated O₂ deficit (the difference between the estimated energy demand and the actual O₂ uptake) was determined during intense exhaustive exercise (2-7min) in elite athletes, and its relationship with muscle buffer capacity, muscle enzymes and muscle morphology was examined. Five oarsmen, fifteen soccer players, and fourteen distance runners ran, and three sprint cyclists cycled intensely to exhaustion (2-7 min). The oarsmen also performed exhaustive rowing. Blood lactate was measured immediately after several submaximal exercise bouts. A muscle biopsy was taken at rest from m. gastrocnemius of the soccer players and runners, and from m. vastus lateralis of the cyclists. The accumulated O2 deficit for the oarsmen, soccer players and runners during treadmill running was 47.3 (range: 29.6-62.4), 49.5 (34.3-73.7) and 51.9 (26.5-85.5) ml O₂ equivalents (“O₂-Eq”)·kg^-1 b.w., respectively, and it was 56.5 (47.5-73.2)ml “O₂-Eq”·kg^-1 for the cyclists during cycling. The O₂ deficit was not related to blood lactate during submaximal exercise, muscle enzyme activity (citrate synthase, 3-hydroxyacyl-CoA-dehydrogenase, lactate dehydrogenase), number of muscle capillaries, %ST fibres or muscle buffer capacity. The accumulated O₂ deficit was 36% higher (p<0.05) during rowing compared to running. The present data suggest that the anaerobic energy production during intense exercise is related to the muscle mass involved. However, it appears that the anaerobic energy turnover is not determined by muscle fibre type distribution, muscle buffer capacity or muscle endurance capacity.

Key words

O₂ deficit - anaerobic energy production - muscle mass - muscle buffer capacity - muscle enzymes - muscle capillaries - intense exercise