CARDIORESPIRATORY RESPONSES TO SEAT-TUBE ANGLE VARIATION DURING STEADY-STATE CYCLING

The effect of seat-tube angle (STA) variation on oxygen consumption (V O2), heart rate (HR), ventilation (V-E), and rating of perceived exert ion (RPE) on 25 trained competitive triathletes and cyclists was evalu ated during 10-min submaximal tests at each of four STAs (69 degrees, 76 degrees, 83 degrees, 90 degrees). Subjects averaged (mean +/- SD) 2 6.5 +/- 6.4 yr of age, 68.5 +/- 9.8 kg, 4.26 +/- 0.58 l . min(-1) for VO2peak, and 76.2 +/- 1.5 degrees for preferred STA. Tests occurred on a modified cycle ergometer (at each subject's preferred dimensions, e xcept for STA) at a power output that averaged 73% of the subjects' VO 2peak and pedaling 90 rpm while using aerodynamic handlebars. Mean VO2 HR, and RPE values at 83 degrees and 90 degrees were significantly lo wer than values at 69 degrees (3.09, 3.10 vs 3.17 l . min(-1); 149.6, 149.9 vs 152.9 bpm; 13.5, 13.5 vs 14.2, respectively; P < 0.05). V-E a t 83 degrees was significantly lower than V-E at 69 degrees (65.2 vs 6 8.2 l . min(-1); P = 0.011). A kinematic analysis found greater hip ex tension, ankle plantar flexion, and a lower-limb orientation more dire ctly over the crank axis when STA increased. Therefore, only the 69 de grees STA appeared to be a detriment to steady-state cardiorespiratory responses during cycling, whereas the 76 degrees, 83 degrees, and 90 degrees STAs elicited similar cardiorespiratory responses.