Influence of light additional arm cranking exercise on the kinetics of V̇O₂ in severe cycling exercise

This study examined the influence of light additional arm cranking exercise on the V̇O₂ slow component observed during severe cycling exercise. During incremental tests, eleven triathletes exercised to exhaustion cycling with leg, cranking with arm and combined arm and leg cranking and cycling (arm work-rates being set at the third of leg work rates) to determine arm, leg and combined arm and leg lactate threshold and V̇O₂max. After these incremental tests subjects performed in random order severe exercises until exhaustion at work-rates corresponding to the lactate threshold + 50% of the difference to the work rate associated with V̇O₂max and the lactate threshold, i.e., Δ50: 1) with legs only (leg Δ50) 2) leg Δ50 plus a very light arm cranking exercise at 25% of the arm lactate threshold (LΔ50 + A25). V̇O₂ slow component was the increase of V̇O₂ (in ml x min^-1) between the third and the sixth minute of exercise (ΔV̇O₂ 6 - 3 min). Results showed 1) Nine of the eleven triathletes had a V̇O₂ slow component in arm Δ50; 2) a light cycle arm exercise (25% of lactate threshold) added to a severe leg cycle exercise did not decrease time to exhaustion in severe exercise (493 ± 154 s vs 418 ± 84, P = 0.4); 3) For the five subjects who had a V̇O₂ slow component in leg cycling, the addition of a light arm exercise (25% of arm LT) decreased the V̇O₂ slow component significantly (from 457 ± 173 ml x min^-1 for leg Δ50 to 111 ± 150 ml x min^-1 for LΔ50 + A25, Z = -2.0, P = 0.04). In conclusion, light additional arm cranking decreases the V̇O₂ slow component in severe cycling. Further studies are needed to confirm the hypothesis that extra work due to an increasing handgrip on the handlebars may contribute to the V̇O₂ slow component in cycling.