Can N-acetylcysteine (NAC) supplementation enhance altitude training in elite runners?
Can N-acetylcysteine supplementation enhance the haematological response and reduce excessive exercise induced fatigue in elite runners during training camps at moderate altitudes?
Australian Institute of Sport
18 participants
Apr 17, 2017
Interventional
Conditions
Summary
Elite 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 n-acetylcysteine (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 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 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 ful l the below criteria:
- Sex: Male and female
- Age range: 18 to 40 y
- Disease status: Healthy individuals
- Elite middle distance runners with a high level of physical fitness (VO2max above 55 ml/kg/min)
- Completed 10 to 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 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
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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 18 days 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 middle distance runners (n = 18) will receive either NAC (1200 mg/d) or a placebo supplement 4 days prior to departure and for the initial 2 wk of a 4 wk training camp (funded by Athletics Australia) in Flagstaff, USA (elevation 2100 m). Performance will be assessed via competitions within the 3 wk preceding and following the 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 (Ferro-Grad C, Abbott Laboratories, Australia - 100 mg elemental iron once daily with dinner for 5 weeks, [1 week pre altitude, 4 weeks at altitude], oral tablet supplement), and participants will be excluded from taking any other antioxidant supplements. Researchers will be present in-person on the training camp to encourage compliance with supplementation and other experimental procedures. 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 sea-level to determine haematological (erythropoietin - EPO, reticulocytes) oxidative (GSH:GSSG ratio, F2-isoprostane) and adaptive (nuclear factor kappa B - 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 GPS watches (Forerunner, Garmin, USA)/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. At the same time-points as venous blood samples, participants will complete a 6 minute running test on a motorised treadmill at a submaximal intensity - 2 x 3 minute stages at 13 and 15 kmph for females and 14 and 16 kmph for males. Heart rate and and subjective rating of perceived exertion will be measured during these trials. This will be included to measure the effect of NAC supplementation on tolerance to exercise at altitude.
Locations(1)
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ACTRN12617000427370