None listed
Conditions
Brief summary
One of the major adaptations of muscle to endurance training is a slower utilization of carbohydrate stored in the muscle (muscle glycogen) and blood glucose and greater reliance on fat oxidation during low intensity exercise. . These adaptations are thought to play an important role in the large increase in the ability to perform prolonged strenuous exercise that occurs in response to endurance exercise training. However, the results of early studies demonstrate ‘carbohydrate dependence’ during prolonged endurance events (i.e. marathon running) lasting up to 3 hours, with little (<10%) contribution from fat to the total fuel requirements of exercise. Using a pharmacological agent Nicotinic acid(also known as Niacin or Vitamin B3) to block the breakdown and liberation of free fatty acids into the bloodstream(lipolysis) and impair rates of fat oxidation during exercise, we will test the hypothesis that carbohydrate is the predominant (>90% of total energy requirements) fuel for muscle oxidation during cycling time trials lasting from 60-120 min. Using a repeated measures design, we will test our hypothesis in 10 well-trained cyclists who, after a standardised diet/exercise control, will each perform six maximal, all-out cycling time-trials (over 60, 90 and 120 min duration), three under conditions where lipolysis and fat oxidation are ‘blocked’ and three under normal conditions (control). We hypothesise that there will be no differences in the time-trial performance for any duration, and that carbohydrate oxidation will be the major fuel for oxidative energy production.
Interventions
Using a repeated measures design, we will test our hypothesis in 10 well-trained cyclists who will each perform six maximal, all-out cycling time-trials (over 60, 90 and 120 min duration), three under conditions where lipolysis and fat oxidation are ‘blocked’ and three under normal conditions (control). Lipolysis will be blocked via orally administered nicotinic acid.
1a) The dose administered for the the 60 min trial will be 20 mg/kg BM
The dose administered for the 90 min trial will be 25 mg/
Using a repeated measures design, we will test our hypothesis in 10 well-trained cyclists who will each perform six maximal, all-out cycling time-trials (over 60, 90 and 120 min duration), three under conditions where lipolysis and fat oxidation are ‘blocked’ and three under normal conditions (control). Lipolysis will be blocked via orally administered nicotinic acid. 1a) The dose administered for the the 60 min trial will be 20 mg/kg BM The dose administered for the 90 min trial will be 25 mg/kg BM The dose for the 120 min trial will be 30 mg/kg BM b)Doses 1x10 mg/kg BM dose 30 mins before trial, 1x5 mg/kg dose 15 min before trial, and 5 mg/kg BM after completion of every 30 min of trial. 2)TT's will be conducted on a stationary bike. 3) wash out period will be at least 72 hr between trials
Sponsors
Australian Catholic University
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Educational / counselling / training
Masking
Blinded (masking used) (Subject, Investigator)
Eligibility
Sex/Gender
All
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
Inclusion criteria: Aged 18-35 years Participants must be engaged in cycling training > 200km/week. Participants must have at least 2 years of competitive cycling experience. VO2max of greater than 60 mL/ (kg BM/min).
Exclusion criteria
Exclusion criteria: Current or prior use of anabolic steroids or other prohibited substances. Contraindications to strenuous physical activity as indicated by cardiovascular risk factor questionnaire.
Outcome results
None listed