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Antioxidants: Friend or foe? – Part 2

2019-04-30 by Peter Hespel & Martijn Redegeld

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Do you go to the gym several times a week to get yourself a ‘summerbody’? And are you considering taking antioxidants to support your training sessions? If so, new research seems to indicate that this is not the best idea, especially when it comes to taking vitamin C and E. A recent study shows that the use of antioxidants can significantly reduce the building of muscle mass. While it was already clear that antioxidants negatively impact the progress of your physical condition during endurance training, it appears that this is also true for strength training.

In a recently published study, young women all followed exactly the same strength training programme. Half of the group took a supplement each day containing 1,000 mg of vitamin C and 400 IU of vitamin E. The other half took a placebo each day. After ten weeks, the placebo group had added an average of 1.4 kg of fat-free mass. In contrast, the group that took antioxidants were ‘held back’ and only added half that amount, namely, 0.7 kg (see graph below). In other words, exactly the same strength training programme was significantly less efficient with respect to building muscle mass.

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Percentage of body weight change after an endurance training program. Source: Dutra et al. Antioxidant Supplementation Impairs Changes in Body Composition Induced by Strength Training in Young Women, Int J Exerc Sci. 2019.

Similarly to endurance training, strength training causes muscle damage as a result of ‘oxidative stress’. You need this stress to make progress, for example to activate the signals to that start muscle protein synthesis after strength training. Taking antioxidants suppresses the muscle damage that occurs during strength training. However, it is precisely this damage that is required as a stimulus for training adaptation, namely muscle growth. In other words, antioxidants help the body during muscle damage recovery, which means the body does not have to work so hard. This means that you lose out because you reduce the benefit from the training… ‘no pain, no gain’.

In brief, this is why we recommend that you do not take antioxidants each day if you want to boost your physical condition, for example by building muscle mass. Important note: consuming small amounts of antioxidants during your normal diet, i.e. in vegetables and fruit, does not impair the benefits of training in any way whatsoever. On the contrary, antioxidants are an essential part of a healthy varied diet. Taking antioxidant supplements during training, however, is absolutely not recommended.

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