Can N-acetylcysteine (NAC) supplementation enhance altitude training in elite swimmers?
Can N-acetylcysteine (NAC) supplementation enhance the haematological response and reduce excessive exercise induced fatigue in elite swimmers during training camps at moderate altitudes?
Australian Institute of Sport
20 participants
Aug 1, 2017
Interventional
Conditions
Summary
Elite swimmers regularly incorporate living and training at altitude into their programs to enhance physiological and performance adaptations. Although altitude training and research has been undertaken previously in swimming the use of a novel dietary supplement to enhance adaptation to altitude training at accessible altitudes would be highly beneficial. Typical training locations in Australia for swimming at altitude typically require additional time and resources to achieve similar physiological adaptations to higher altitudes overseas. Additionally swimming can add an additional hypoxic stressor to altitude training that NAC may help support and hence reduce the risk of illness or overtraining seen when swimmers travel to altitude. 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, part of a series of studies will be the first to comprehensively examine the acute and medium term 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 performance 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 in elite swimmers.
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
- Elite swimmers with 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 Criteria12
- Participants will be excluded from participantion 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
- Participants with low ferritin levels (30-100ug/L) prior to the commencement of the study will be required to take daily oral iron supplement (Ferrograd C: 100 mg elemental iron) during the course of the study.
- 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
Interested in this trial?
Get notified about updates and connect with the research team.
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 2.5 weeks Randomised parallel groups matched pair design. This study design is optimal as it allows for comparison of the intervention effects between closely matched participants while avoiding the impracticality of using two within-subjects factors, i.e. long washout period required between interventions. Elite swimmers (n = 20) will receive either NAC (1200 mg/d) (n=13) or a placebo (n=7) supplement 4 days prior to departure and for the initial 2 wk of a 4 wk training camp (funded by Swimming Australia) in Thredbo, AUS (elevation 1300 m). Select athletes (random allocation) in the supplementation group (n=7) will also spend 10-12 hours per day (7-9 hours nightly, 2-3 hours during the day) exposure to normobaric hypoxia (simulated altitude 3000 m, 17% oxygen) via the use of hypoxic tents which will occur during the entire 4 week altitude training camp. Researchers will be present in-person on the training camp to encourage compliance with supplementation and other experimental procedures. Performance will be assessed via a 2km swim time trial and an incremental swim step test pre, post and 1 week post the altitude training camp. Baseline measures for blood iron status (serum iron, ferritin, transferrin saturation, iron incorporation) will be taken to determine suitability (see exclusion criteria under eligibility) for iron supplementation at altitude (prescribed daily for 5 weeks, 1 week prior to altitude training and entire 4 weeks altitude training, Ferro-Grad C, Abbott Laboratories, Australia - 100 mg elemental iron once daily with dinner, oral tablet supplement)), and participants will be excluded from taking any other antioxidant supplements. Venous blood samples will be taken at baseline (pre-departure to altitude), after 36 h and 2 wk at altitude, and immediately prior return to sealevel to determine haematological (EPO, reticulocytes) oxidative (GSH:GSSG ratio, F2-isoprostane) and adaptive (NFKB) responses to altitude training and supplementation. Haemoglobin mass will be assessed via CO rebreathing pre and post altitude training. Throughout the investigation, athletes will complete a daily wellness diary to assess the impact of supplementation on athlete health, incidence of illness and tolerance to training. Training load will be individualised to each athlete by personal coaches, and monitored using session RPE throughout the altitude intervention, and 4 wk prior. Participants will be randomly matched in pairs according to baseline; ferritin status, training load, gender and performance
Locations(1)
View Full Details on ANZCTR
For the most up-to-date information, visit the official listing.
ACTRN12617000426381