The goal of this clinical trial is to understand how the body responds to short-term, severe low energy availability (LEA) in healthy, weight-bearing endurance athletes aged 18-45 years old. LEA describes a mismatch between an individual's dietary energy intake and the energy cost of their commitments for training and competition. The main questions this trial aims to answer are:
1. What effect does short-term, severe LEA have on sleeping metabolic rate? 2. What effect does short-term, severe LEA have on other body systems identified within the Relative Energy Deficiency in Sport (REDs) Health and Performance Conceptual models?
Researchers will compare a control trial with both a LEA trial achieved through diet restriction and a LEA trial achieved through increased exercise to see if there are differences in the body's response.
Participants will complete three 6-day trials, a minimum of 3-weeks apart, involving:
* Prescribed diet (all food provided) * Prescribed running and/or cycling exercise * Two visits to ACU Fitzroy campus for blood tests and exercise testing * 50 hour stay (two nights and two days) in the ACU metabolic chamber
18-45 years old
Well trained weight-bearing athlete (tier 2-4 1)
Perform ~45km per week of weight-bearing endurance training, and able to undertake the prescribed exercise in each trial condition
Pass the ESSA pre-exercise screening tool and/or obtain GP clearance to exercise
Assessment of red status on the REDs Clinical Assessment Tool
Unable to attend ACU in Fitzroy, Victoria, for the 6 study visits for completion of the study protocol
Pregnancy
Use of hormonal contraceptive with the previous 3 months
Crossover
Diet-induced low energy availability
Other intervention6-days of severe low energy availability (LEA, 15kcal/kg FFM/d), achieved by superimposing restricted energy intake on the control trial.
Exercise-induced low energy availability
Other intervention6-days of severe low energy availability (LEA, 15kcal/kg FFM/d), achieved by superimposing increased exercise energy expenditure on the control trial.
Sleeping metabolic rate between trials, measured using a human metabolic chamber on night 5 of each trial condition.
The primary outcome is the within-participant and sex-based difference in Sleeping Metabolic Rate (SMR) across the three trial conditions. Analyses will also compare differences in SMR responses between sexes.
Fasting values of metabolic and reproductive hormones between trials.
Within-participant and sex-based changes in fasting values of metabolic and reproductive hormones (testosterone, estrogen, progesterone, IGF-1, T3, leptin, iron status, lipids, glucose/insulin). Measured via venous blood sample on day 1 and day 5 of each trial.
Overnight pulsatility of luteinising hormone between trials.
The secondary outcome is within-participant and sex-based difference in overnight pulsatility of luteinising hormone. This will be measured via venous blood samples taken every 15 minutes for 8 hours on night 4 of each trial.
Overnight pulsatility of growth hormone between trials.
The secondary outcome is within-participant and sex-based difference in overnight pulsatility of growth hormone. This will be measured via venous blood samples taken every 15 minutes for 8 hours on night 4 of each trial.
Overnight pulsatility of cortisol between trials.
The secondary outcome is within-participant and sex-based difference in overnight pulsatility of cortisol. This will be measured via venous blood samples taken every 15 minutes for 8 hours on night 4 of each trial.
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Australian Catholic University
Lead sponsor
Wu Tsai Human Performance Alliance
Collaborator
