EFFECTS OF ANTIOXIDANT SUPPLEMENTS COMBINED WITH RESISTANCE EXERCISE ON GAINS IN FAT‐FREE MASS IN HEALTHY ELDERLY SUBJECTS: A PILOT STUDY

To the Editor: Although resistance training is promoted to increase fat-free mass (FFM) in older adults,1 50% of clinical trials report no meaningful effects of resistance training on FFM in older persons.2 One potential explanation is that oxidative stress, which characterizes the process of aging, may minimize the adaptations to resistance exercise3 and may attenuate muscle cell hypertrophy. Although regular exercise training enhances adaptive responses, thereby diminishing oxidative stress in younger individuals,4 it appears that aging may attenuate these adaptations.5 It thus has been proposed that elderly people who exercise have a greater dietary antioxidant requirement,6 especially for vitamin E.7 To our knowledge, no studies have specifically examined changes in FFM in response to high-intensity resistance training combined with dietary antioxidants in older men and women. The purpose of this study was to investigate whether 6 months of resistance training combined with antioxidant treatment could produce greater increases in FFM than one or no intervention. Sixty-one older men (n=27) and women (n=34) (aged 65.8±3.7, range 60–75) were recruited to participate in a double-blind controlled study and were randomly assigned to one of four groups: placebo (PL), placebo+resistance training (PL+RT), antioxidant (AO), and antioxidant+RT (AO+RT). Subjects had to be physically healthy and not use supplements or medication. The ethics committee of the Sherbrooke Geriatrics University Institute approved the procedures. Before and after 6 months of intervention, subjects were submitted to metabolic testing, including body composition (dual-energy x-ray absorptiometry), dietary intake (3-day food record), and plasma alpha-tocopherol concentrations (reverse-phase high-performance liquid chromatography). The resistance training program consisted of three sessions per week of eight different resistance exercises (3 × 8 repetitions at 80% of one-repetition maximum). Antioxidant treatment consisted of 600 mg per day of vitamin E (dl-α-tocopherol) and 1,000 mg per day of vitamin C (ascorbic acid) or a placebo. These daily doses have been shown to beneficially alter the oxidative profile of physically active adults.8 The investigators maintained close control of adherence for the exercise and antioxidant or placebo treatment. A one-way analysis of variance (ANOVA) was performed to assess differences between groups at baseline. Repeated-measure ANOVAs were used to examine the treatment effect on all variables when adjusting for sex. Paired t-tests were used to examine differences between baseline and postintervention measurements in each group. All analyses were performed with SPSS software version 13.0 (SPSS Inc., Chicago, IL). As shown in Table 1, groups were similar at baseline for all variables. Both RT groups showed similar significant increases in strength (all P≤.001). Nevertheless, a significant treatment effect (time × group interaction) was found for FFM and muscle mass index (MMI) (P≤.01). As such, there was an increase of 0.5±1.4 kg in the RT group, whereas the AO+RT group had an increase of 1.3±1.2 kg of total FFM. Adequate absorption of vitamin E was ensured by measuring plasma concentrations of alpha-tocopherol, which showed that the AO and AO+RT groups had significant increases (P≤.05), whereas the PL and PL+RT groups showed no change. To our knowledge, this is the first study to examine the effect on FFM and MMI in older adults when antioxidant supplements are combined with 6 months of resistance training. These preliminary findings show that antioxidants provided a significantly greater beneficial effect when combined with resistance training on FFM and MMI gains than resistance training alone, supporting the hypothesis that vitamins C and E reduce damage induced by muscle contraction and possibly intervene in the inflammatory response associated with high-intensity resistance exercise.9 This may, in turn, potentialize the effect of exercise on muscle mass gains. From a clinical standpoint, this study does not provide sufficient information to establish new clinical recommendations regarding vitamin E and C intakes for healthy exercising elderly people. Nevertheless, prudent recommendations in this population should be to ensure adequate vitamin E intake and a diet containing a mix of different antioxidants from functional foods. Older adults are at a greater risk for nutritional deficiencies,10 and there is little information regarding antioxidant requirements for exercising elderly people. Further research is needed to determine appropriate recommendations for this population, especially because nutrition and exercise are two effective and accessible strategies for health maintenance in the elderly population. These results demonstrate that 6 months of antioxidant supplements combined with resistance training increases FFM and MMI in older adults more than resistance training alone. These preliminary results raise interesting hypotheses that merit further exploration. The study was funded by the Canadian Diabetes Association. Vitamin E and placebos were graciously supplied by Arkopharma, Ltd (Carros, France). IJD received a salary grant from the Canadian Institute of Health Research and AK from the FRSQ. ML held a scholarship from the Faculty of Physical activity and Sports of University of Sherbrooke. Conflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this letter. Author Contributions: M Labonté: study concept and design, acquisition of subjects and/or data, analysis and interpretation of data, and preparation of manuscript. DR Bouchard: acquisition of subjects and/or data, analysis and interpretation of data, and revision of manuscript. M Senechal: acquisition of subjects and/or data, analysis and interpretation of data, and revision of manuscript. F Bobeuf: acquisition of subjects and/or data, analysis and interpretation of data, and revision of manuscript. A Khalil: study concept and design, analysis and interpretation of data, and revision of manuscript. D Tessier: study concept and design, analysis and interpretation of data, and revision of manuscript. IJ Dionne: study concept and design, analysis and interpretation of data, and preparation of manuscript. Sponsor's Role: None.

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