ANAEROBIC ATP PRODUCTION AND ACCUMULATED O-2 DEFICIT IN CYCLISTS

Anaerobic ATP production in skeletal muscle and the accumulated oxygen deficit (O2D) incurred during an exhaustive cycle bout (duration = 17 3 +/- 24 s; intensity = 112 +/- 3% VO2peak), were determined in 10 mal e cyclists (mean +/- SD: VO2peak = 69.8 +/- 4.2 ml . kg(-1) min(-1)). Anaerobic ATP production (mmol . kg(-1) d.w.) was determined from chan ges in lactate, phosphocreatine, ATP, and ADP in vastus lateralis. Mus cle buffer value and the activities of glycogen phosphorylase (PHOS), phosphofructokinase and citrate synthase (CS) were also determined. Th e anaerobic ATP production determined from measured muscle metabolites was 202.7 +/- 46.9 mmol . kg(-1) d.w. and was correlated (P less than or equal to 0.05) with muscle buffer value (r = 0.81), PHOS (r = 0.69 ) and the ratio of PHOS to CS activity (r = 0.77). The O2D was 55.2 +/ - 10.3 ml O-2 Eq . kg(-1), but was not correlated (P > 0.05) with anae robic ATP production (r = -0.38), buffer value (r = -0.50) or PHOS (r = -0.39). These latter findings could be explained by error in measuri ng the O2D and/or muscle anaerobic ATP production in well-trained cycl ists.