Abstract des Autors

The aim of this study was to assess the changes determined by increased cadence on skeletal muscle oxygenation during cycling at an exercise intensity equal to the ventilatory threshold (T vent ). Nine healthy, active individuals with different levels of cycling experience exercised at a power output equal to T vent , pedaling at cadences of 40, 50, 60, 70, 80 and 90 rpm, each for 4 min. Cadences were tested in a randomized counterbalanced sequence. Cardiopulmonary and metabolic responses were studied using an ECG for heart rate, and gas calorimetry for pulmonary oxygen uptake and carbon dioxide production. NIRS was used to determine the tissue saturation index (TSI), a measure of vastus lateralis oxygenation. TSI decreased from rest to exercise; the magnitude of this TSI reduction was significantly greater when pedaling at 90 rpm (−14±4%), compared to pedaling at 40 (−12±3%) and 50 (−12±3%) rpm (P=0.027 and 0.017, respectively). Albeit small, the significant decrease in ΔTSI at increased cadence recorded in this study suggests that skeletal muscle oxygenation is relatively more affected by high cadence when exercise intensity is close to T vent.