Children participating in swimming training exhibit increased oxidative stress
Oxidative stress in swimmers
In recent years, the concept of exercised-induced ‘oxidative stress’ (damage caused within cells at the molecular level as a result of increased oxygen metabolism) has become much more widely understood by athletes and coaches. While maximising oxygen uptake is a good thing for athletic performance, the price paid is potentially damaging increased oxidative stress (a bad thing), which explains the growing interest in the role of protective antioxidants in the diets of endurance athletes.
Now new research carried out on swimmers by Greek researchers indicates that increased oxidative stress can also affect child athletes. This study looked at 17 trained young swimmers with an average age of 10.1 years and compared them with 12 age-matched non-athletes. In particular, the researchers looked at two types of markers in the blood; those that are associated with increased oxidative stress (such as thiobarbituric acid-reactive substances or TBARS) and other markers associated with protective antioxidant capacity (such reduced glutathione or GSH) and which would indicate protection from oxidative stress.
The results showed that reduced glutathione (GSH) was 37% lower in the swimmers compared to non-athletes and that oxidised glutathione (GSSG – this is glutathione that has reacted with oxygen radicals) was not different. This in turn meant that the ratio of GSH/GSSG) was 43% lower in swimmers compared to non-athletes (the lower this ratio, the greater the oxidative stress in the body). Moreover, TBARS concentration was 25% higher in swimmers compared to controls (indicating higher oxidative stress) and total antioxidant capacity (a measure of the body’s overall ability to combat oxidative stress) was 28% lower.
The authors comment that children participating in swimming training exhibit increased oxidative stress and less antioxidant capacity compared to untrained counterparts, which suggests they may be more susceptible to oxidative stress induced by chronic exercise. These findings raise a number of questions such as whether children (whose diets are often low in antioxidant fruits and vegetables) should supplement antioxidant nutrients and whether this increased oxidative stress could have other implications for a growing body.
Eur J Appl Physiol 2007; 28 [Epub ahead of print]
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