 assuming the near horizontal position during a maximal oxygen uptake (Vo2max) test. They found a significant advantage in Vo2max, maximum work output, and maximum ventilation in the aero position compared with the upright position. Origenes et al3 hypothesised that cyclists in the aero position should show a higher breathing frequency but smaller tidal volume (as the result of a possible restriction). Some studies1,3 have suggested that the aero position is like the catch phase of rowing, where restriction is placed on the abdomen and thorax. However, these studies, unlike that of Faria et al,6 failed to show any significant ventilation differences between positions. More recently, Sheel et al7 found that the aero position provided energy savings, whereas Gnehm et al8 concluded that the aero position increased the metabolic costs of cycling, and Grappe et al9 found no difference between positions for some variables.
Most studies on the impact of position on performance have used trained athletes.1–3,10 Because training creates adaptation to the equipment and the near horizontal position, the physiological response in trained athletes may not generalise to most recreational cyclists. To our knowledge, there are no published studies on the physiological impact of position on untrained participants.
Previous studies of body position and cycling have investigated brief incremental exercise. Berry et al1 suggested that ventilation changes only become apparent after prolonged exhaustive exercise. For example, the restrictive nature of the aero position may impair the ability to sustain the position for long periods. This illustrates the need to investigate the effect of the aero position for various durations and intensities of cycling. Thus, the purpose of this investigation was to measure the cardiorespiratory response of recreationally fit young men, who were unfamiliar with aerobars, in standardised aero and the upright positions. Studies were performed during both maximal testing and submaximal exercise using a test-retest design with the participant acting as their own control.
Twelve healthy, physically active but untrained men were recruited from the University of Adelaide using advertisements on poster boards. The inclusion criteria were non-smokers aged 17–25 years. Recreational or competitive cyclists were excluded from the study as were those with known cardiovascular or respiratory conditions, smokers, and those with aerobar experience. Two participants were excluded because of an inability to complete the exercise protocol.
Each participant was asked to refrain from any stimulants (caffeine, drugs, cigarettes, etc), exercise, or alcohol for 12 hours before the testing. Each had eaten a light breakfast/lunch at least two hours before each experimental protocol. Normal hydration was requested. All testing was completed within a six week period in an air conditioned laboratory with a constant temperature of 21.2°C and 50% humidity. Approval for the experimental protocol was obtained from the human ethics committee of the University of Adelaide. Written informed consent was obtained from the participants.
Each participant completed four tests: Vo2max test in the upright and aero positions, in addition to a 45 minute steady state exercise protocol in both aero and upright positions. The tests were performed on four separate days. The 45 minute steady state protocol involved cycling for 15 minutes each at 50, 100, and 150 W. Cadence was maintained at 60 repetitions per minute. Blood samples were taken every 2.5 minutes for lactate analysis. The volume of blood removed by the venous blood sampling was replaced seriatim with an equivalent volume of normal saline to maintain blood volume.
Aero and upright position
Participants were randomised into two groups (n = 5). Group 1 exercised first in the upright position, then in the aero position, on different days. Group 2 exercised in the aero position first, then in the upright position, again on different days. In the upright position participants sat with their trunk perp