The effect of water dousing on heat strain and performance during prolonged exercise in trained cyclists

Materials and procedures: -Once enrolled into the study, participants will complete one familiarisation session and two experimental trials in an environmental chamber. Every session will involve only an individual participant completing the trials. -Each experimental session will take approximately 3 to 4 hours and are undertaken 3-7 days apart (washout period). -The familiarisation session will occur 3-7 days prior to the first experimental session and take approximately 3 hours and requires participants to complete an incremental test to exhaustion and a 30 km time trial on the bike. The incremental test to exhaustion will be conducted in temperate conditions (22°C and 50% relative humidity) on a bicycle ergometer with a metabolic cart to measure gas exchange. The test will consist of an initial four minute submaximal steady state exercise intensity, followed by the power output increasing by 25 W every minute until volitional exhaustion. - The two experimental sessions (intervention and control) require the participant to complete both a 30 km self-paced time trial and a 48 min fixed-intensity (65% of maximal oxygen consumption) cycle in an environmental chamber set to 35°C and 20 % relative humidity. A 60 min recovery period for rest, refuelling, and rehydrating will occur in-between the two efforts. The mass of participants will be re-measured prior to the start of the fixed-intensity effort to ensure they have lost no more than 1% of body mass (via sweat) in comparison to the start of the session. Additional fluid (water) will be provided to the participant, if necessary, to ensure that they start within 1% of body mass loss. - The intervention trial will include the self-paced 30 km time-trial where water will be doused on the participant’s arms, upper legs, chest and back of the neck. Dousing will occur immediately before the start of the time-trial and every 5 km throughout. Each douse the bike will be stopped and the participant will dismount to pour 500 ml of water evenly across the dousing sites (~1 min in total duration). The water will be approximately equal to air temperature (i.e. will not be cooled [~35°C]) to mimic water which may have been in an on-bike bidon for an extended period. During the fixed intensity effort (at 65% of maximal oxygen consumption), the same dousing procedure will be followed, starting at 0 min, and then recurring every 8 min. Participants will not be able to rehydrate during both exercise times. Sessions will include the participants experiencing air velocity from fans that is equivalent to ~25-32 km/h. -Cycling efficiency (via the use of a metabolic cart) will be tested immediately before and after the 30 km time-trial. -A 30 km cycling time-trial is a common test used in the research literature and will allow sufficient time to induce meaningful heat strain. The fixed-intensity effort will determine the isolated effects of water dousing on body temperature by fixing the metabolic heat production through a constant (fixed) intensity design. The power output of 65 % of VO2max is classified as moderate aerobic exercise and can typically be sustained for 1-3 h. Who will deliver: A sport science graduate will lead data collection, and the remainder of the team are experienced researchers with 10-20 years of academic experience. Mode: In-person testing of individual participants Location: Environmental chamber at the Mile End campus of Adelaide University. Adherence: Research team member/s will supervise the participants at all times in the environmental chamber to ensure adherence to the study protocols.