Can N-acetylcysteine (NAC) supplementation enhance exposure to altitude in well-trained cyclists?
Can N-acetylcysteine (NAC) supplementation enhance the haematological response and reduce excessive exercise induced fatigue in well trained cyclists during exposure to moderate altitudes?
Australian Institute of Sport
12 participants
Apr 1, 2017
Interventional
Conditions
Summary
Athletes regularly incorporate living and training at altitude into their programs to enhance physiological and performance adaptations. It can be logistically difficult and expensive for Australian athletes to gain the benefits of altitude training. Current options available in Australia are limited to relatively low levels of natural altitude or the use of artificial hypoxic environments. Preliminary data suggests that supplementation with the antioxidant nacetylcysteine (NAC) may boost the erythropoeitic response (i.e. increase red blood cell production) to hypoxia and support the immune system during strenuous training blocks. However, to date, the efficacy of NAC to enhance these physiologic systems has not been determined in an applied sports setting. This investigation forms part of a series of studies will be the first to comprehensively examine the acute effects of NAC supplementation to augment the physiological adaptations to hypoxic exposure in elite athletes. It will also contribute to the existing knowledge regarding the ergogenic effect of NAC on repeat sprint cycle performance in well trained cyclists and add further real-world data to the debate regarding the potential blunting of cellular adaptations with antioxidant supplementation. Importantly, it will also provide valuable information to physiologists, coaches and athletes regarding the prescription and periodisation of NAC supplementation and the optimal integration of hypoxic interventions to produce peak performance during targeted competitions.
Eligibility
Inclusion Criteria8
- For inclusion in the investigation, participants must fulfil the below criteria:
- Sex: Male and female
- Age range: 18 to 40 y
- Disease status: Healthy individuals
- Well trained cyclists with a high level of physical fitness (VO2max above 55 ml/kg/min)
- Completed 10-15 hrs of training per week for at least 2 years
- Willingness to give written and oral informed consent.
- Willingness to participate to and comply with the study.
Exclusion Criteria11
- Participants will be excluded from participation based on the below criteria:
- Regular NAC supplementation use for the previous 6 months
- Illness or injury which may be exacerbated through participation in the study
- Exposure to a hypoxic stimulus in the previous 3 months
- Inconsistent pretesting diet and exercise
- Women lactating, pregnant or of childbearing potential who are not willing to avoid becoming pregnant during the study.
- Patients with a history of a psychological illness or condition such as to interfere with the patient's ability to understand the requirements of the study.
- Patients with a haematological disease that is likely to interfere with the evaluation of the patient's safety and of the study outcome.
- The following medication(s) can have interactive effects, may confound the findings of the investigation and may interfere with the patient's ability to meet the study requirements; they cannot be administered during the clinical study:
- Any antioxidant vitamins and mineral supplement
- Any substance or method included in the World Anti-Doping Association List of Prohibited Substances and Methods. Unless the participant has a Therapeutic USE Exemption for the substance /method from the Australian Sports Anti-Doping Authority
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Interventions
Supplementation with N-acetylcysteine (NAC) in a randomised, double-blind, placebo controlled study to assess the effects of supplementation on erythropoiesis, exercise-induced inflammation and performance during altitude training in athletes. N-acetylcysteine (NAC) will be administered orally in tablet form, 1200 mg per day, daily for 2 weeks. Supplementation will occur for a 6 day loading period prior to the first of 3 experimental trials, and for the duration of the exercise trials (1 week). Double blind randomised placebo controlled crossover design. Well trained cyclists (n=12) will receive either NAC (1200mg/d) or a placebo supplement. Participants will complete 3, 2 h trials in each condition. Trials will be conducted in a hypoxic chamber located at the NSW Institute of Sport and administered/supervised by one of the researchers (exercise physiologist). On the days of the exercise trials, the daily dose of NAC/placebo will be taken 2 hours prior. Control, seated in normoxia Hypoxia, seated in fraction of inspired oxygen [FiO2]=15% Exercise + hypoxia, FiO2=15%, 30 min seated, incremental cycle test to exhaustion (starting at a power output of 2 Watts per kg body mass, increase 50 watts every 3 minutes until exhaustion), 20 minutes recovery, repeat sprint protocol (3 sets of 12 x 5 s efforts with 30 s rest - interspersed with 5 min recovery) Venous blood samples (pre, post and 2 h post) will be taken to assess hypoxic inducible factor 1alpha, nuclear factor kappa B, EPO, gluthathione:reduced glutathione ratio (GSSG:GSH) and a full blood count. At least 36 h between each trial and a 3 wk washout between conditions.
Locations(1)
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ACTRN12617000425392