None listed
Conditions
Brief summary
Exercise performance is impaired in hot conditions compared with temperate conditions. During exercise in such thermally stressful conditions, fluid loss through sweat production to liberate heat from the body is accelerated, which can adversely impact cardiovascular and thermoregulatory function and ultimately hinder exercise performance. To increase the total fluid pool available for sweat production, ingestion of nutritional aids such as glycerol and sodium prior to exercise may increase total body water above normal body water levels (i.e., euhydration) prior to exercise, which is known as hyperhydration. This topic requires further investigation to determine if hyperhydration is a viable preparation strategy for endurance running in hot conditions. The hypothesis for this study is that the combined ingestion of glycerol and sodium will result in a significantly greater fluid retention than the control and this will improve half-marathon time-trial performance in hot ambient conditions.
Interventions
In a randomized and cross-over fashion, participants will complete either a hyperhydration protocol or a control protocol before completing a half-marathon under race conditions in the field (i.e., outside the laboratory), in hot ambient conditions.
The hyperhydration protocol involves ingestion 1.2 g/kg of body mass (BM) of glycerol + 7.5 g/L of sodium chloride with a large bolus of fluid totalling 25 ml/kg BM. The fluid bolus is an artificially sweetened beverage made to the manufacturers in
In a randomized and cross-over fashion, participants will complete either a hyperhydration protocol or a control protocol before completing a half-marathon under race conditions in the field (i.e., outside the laboratory), in hot ambient conditions. The hyperhydration protocol involves ingestion 1.2 g/kg of body mass (BM) of glycerol + 7.5 g/L of sodium chloride with a large bolus of fluid totalling 25 ml/kg BM. The fluid bolus is an artificially sweetened beverage made to the manufacturers instructions. The sodium will be orally consumed using opaque coloured, dissolvable tablets to protect from the salty taste. Glycerol will be orally ingested and mixed in with the large bolus of fluid. Each intervention will be orally ingested in 4 equal portions over a 60 minute period (i.e., minute 0, 20, 40 and 60). Although the intervention treatment is consumed at different time points, these are not independent interventions. The entire treatment is split into doses to manage the potential gastrointestinal discomfort that may occur with ingesting large amounts of fluid. Participants will be instructed to consume their bolus at each time point within five minutes and will be monitored by the research team to ensure adherence. As this is a cross-over trial, each trial will be completed with a wash-out period of at least 14 days.
Sponsors
Deakin University
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Prevention
Masking
Blinded (masking used) (Subject)
Eligibility
Sex/Gender
All
Age
18 Years to 45 Years
Healthy volunteers
Yes
Inclusion criteria
The inclusion criteria for this study is: trained males and females, aged 18-45 years. To be classified as 'trained', potential participants must be completing running based trained greater than or equal to 3 times per week and greater than or equal to 5 hours per week as per published criteria for participants completing exercise-based studies.
Exclusion criteria
Exclusion criteria includes any abnormal renal function, use of diuretics or creatine in the previous eight weeks as these factors can effect the body's fluid retention capability. Participants that have previously suffered from heat illness and those that have an impairment that affects thermoregulation will also be excluded. Participants will be excluded if they answer 'Yes' to any of the first six questions in stage one of the Exercise and Sport Science pre-screening tool. Participants will also complete stage 2 of the Exercise and Sport Science pre-screening tool, those that have multiple (i.e., 2 or more) risk factors will be asked to seek medical advice before participating in this project. Participants must not have sustained a lower limb injury in the previous six months and have no current injury that will impair their ability to complete the exercise protocol. Participants will also be excluded if they have a history of migraines, chronic headaches or liver disease as it is recommended that these populations avoid glycerol ingestion. Participants who are allergic to the nutritional aids used in the study (i.e., glycerol or sodium chloride) will also be excluded.
Outcome results
None listed