Effects of Pedal Frequency on V̇O₂ and Work Output at Lactate Threshold (LT), Fixed Blood Lactate Concentrations of 2mM and 4mM, and max in Competitive Cyclists

 

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Abstract

To determine the effects of differing pedal frequencies on V̇O₂ and work output values at the lactate threshold (LT), fixed blood lactate concentrations of 2mM and 4mM (2 mM, 4mM), and at max, nine male competitive road racing cyclists (USCF category I or II) completed three V̇O₂max tests; on a Monark bicycle ergometer, at pedal frequencies of 60, 90, and 120rpm. Each stage was 3 min in duration, starting at 0 kgm/min with subsequent stages increased by either 180 kgm/min (60 and 120 rpm) or 178 kgm/min (90 rpm). Blood samples were taken during the last 30 s of each stage. V̇O₂ and work output at LT, 2 mM, and 4mM were determined from individual blood lactate-work rate and V̇O₂-work rate relationships. V̇O₂max and maximal work output were chosen as the peak values observed during the V̇O₂max tests. Results indicated that work output at LT, 2mM, and 4mM was affected by choice of pedal frequency (1278, 1140, 999 kgm/min at LT; 1533, 1450, 1182 kgm/min at 2 mM; 1780,1703,1487 kgm/min at 4mM; for 60, 90, and 120 rpm, respectively, P < 0.05). Max work output at 60 and 90 rpm was significantly greater P < 0.05) than at 120 rpm (2035, 2053, 1879 kgm/min for 60, 90, and 120 rpm, respectively). V̇O₂ values at LT, 2mM, and 4mM and max were also affected by pedal rate (41.31, 37.20, 39.99 ml/kg·min^-1 for V̇O₂ at LT; 49.70, 45.44, 44.82 ml/kg·min^-1 for V̇O₂ at 2mM; 56.79, 51.51, 52.13 ml/kg·min^-1 for V̇O₂ at 4mM; 65.06, 61.28, 61.73 ml/kg·min^-1 for V̇O₂max with 60, 90, and 120 rpm, respectively, P < 0.05). It was concluded that, in competitive cyclists, use of 60rpm may besuperior to 90 or 120 rpm for laboratory assessment of V̇O₂ values at LT, 2mM, 4 mM, and max; and for work output values at LT, 2mM, and 4mM.