est-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 perpendicular to the ground. They maintained an anterior pelvic tilt and kept their trunk in the upright cycling position. In the aero position the participants assumed a crouched position, with their trunk held parallel to the ground. They were asked to maintain a posterior pelvic tilt and to allow their thoracic spine to “drop” towards their thighs. Wrists and hands rested on the aerobars. All participants were monitored and given verbal feedback to maintain the positions.
Maximal oxygen uptake
Two Vo2max tests were completed on each participant (aero and upright). Vo2 was measured with an online, indirect calorimetry system. Participants exercised on a Monark stationary bicycle. The standard Monark handlebars were modified with clip on aerobars (Bioarm, Italy) with forearm pads for the aero position. Seat height was set for each participant with 25–30° flexion in the extended leg. Seat height for each participant remained constant for the four protocols. Leg length was measured from the anterior superior iliac spine to the distal portion of the lateral malleolus.
Each participant was fitted with a nose clip and mouthpiece attached to a Hans Rudolph two way R2700 valve. This was passed through a metre of large bore tubing to a 2.6 1itre mixing chamber from which dried gas was sampled continuously. A Labview On-line computer system was used to perform the calculation of Vco2, Vo2, minute ventilation (Ve), tidal volume, and respiratory exchange ratio every 30 seconds. Heart rate was recorded continuously using a Polar Electro PE3000 Sportstester heart rate monitor (information recorded every 15 seconds).
The protocol for both maximum tests started with a five minute warm up followed by a five minute rest. The participant then began cycling at 50 W increasing to 100 W after one minute. The workload was then increased by 25 W every minute until volitional exhaustion or he reached a plateau in heart rate and/or Vo2 response. The max tests were performed on two different days at approximately the same time, one to two we