eks apart.
Steady state sessions
After the participant had assumed the experimental position (aero or upright), exercise started at 50 W and continued for 45 minutes at the three absolute workloads previously outlined. Blood samples were taken every 2.5 minutes as previously described.
Venous catheters were inserted into the antecubital vein. An initial 2 ml of the catheter system contents (blood saline mixture) was discarded before withdrawal of the main 3 ml sample. Between samples, the catheter system was flushed with 12 ml heparinised saline to prevent clotting. From each main sample, 1 ml was immediately deproteinised in 2 ml ice cold 8% perchloric acid. The samples were vortex mixed and centrifuged, and the supernatant was frozen at −20°C for later enzymatic analysis of lactate.
Gross mechanical efficiency
The percentage gross mechanical efficiency (%GME) was calculated from the following equation at the final minute of each workload (steady state):
Individual mean maximal exercise data were analysed with a paired t test. The steady state exercise data were analysed using the last five minutes of each of the three levels of intensity (50, 100, 150 W). Submaximal exercise data were analysed using paired t tests and repeated measures analysis of variance. Data are reported as mean (SD).
The participants had a mean age of 19.1 (1.10) years, height of 181.95 (4.27) cm, mass of 70.98 (3.12) kg, and body mass index of 21.46 (1.21).
Table 1 summarises maximal values for participants in both aero and upright positions during one minute of incremental exercise testing. Participants had a significantly higher Vo2max (ml/kg/min), heart rate maximum, and VEmax, and achieved a greater workload in the upright position. There was no significant difference between positions for Vo2max measured in litres/min.
Steady state exercise
During submaximal work at three absolute work outputs (50, 100, 150 W), variables increased in a stepwise fashion as intensity of exercise increased (table 2). A significant difference was found between positions for Vo2 using a repeated measures analysis of variance. Other variables did not differ between groups (figs 1 and 2).
Gross mechanical efficiency
The %GME increased as exercise progressed in both positions. There was a significantly higher value obtained for the upright position at 50 and 100 W, which was not significant at 150 W.
Physiological response to the aero position is not well understood, and previous results using “trained” participants are inconsistent. The conflict of previous results may be due to different experimental controls, experience of the cyclists, or the adaptation of training. To our knowledge, no studies have investigated the response of untrained cyclists to the variation of positions. For this reason, this study is unique in that: participants were unfamiliar with aerobars and the crouched position; results were obtained using standardised positions and several different exercise intensities and durations were tested.
In the maximal exercise testing, significant differences were found in Vo2max, Ve, heart rate maximum, and maximal workload. The crouched aero position was associated with smaller increases in tidal volume compared with the upright position. Subsequent reliance on increased breathing frequency was associated with earlier termination of exercise. Origenes et al3 believed that cyclists in the aero position should show a higher breathing frequency but smaller tidal volume and therefore higher inspiratory flows caused by a possible restriction imposed by the position.
Franke et al2 found that the aero position gave higher stroke volume at rest resulting from an increased pre-load. They did not find this phenomenon during exercise. If the assumption that the aero position provides a greater stroke volume is true, but heart rate remains the same in both positions, one would expect to see some advantages resulting from greater cardiac output. However, this may be difficult to measure non-invasively. The crouched aerobar position may impair the ability to increase