Medicine & Science in Sports & Exercise

Evidence suggests exercising in hypoxia can produce a stress response, characterized by increased negative mood, and relatively poor performance. Lane and Terry 2000) suggested that depressed mood is the most influential mood dimension, and that individuals reporting it tend also to report mood disturbance.

PURPOSE

To investigate: 1) mood changes during a two-hour cycling test during hypoxic and normoxic conditions, and 2) mood dynamics that lead to depressed mood.

METHODS

Eight volunteer male elite cyclists performed two 50-mile cycle bouts on a cycle ergometer. Trials were randomly assigned from normobaric normoxia and normobaric hypoxia (2,500 metres), and were separated by two weeks. Both cycle bouts were performed at an intensity equivalent to lactate threshold. Mood was assessed before, after one hour, after two hours and on completion of the 50 mile ride using the 24-item Brunel Mood Scale.

RESULTS

Repeated measures ANOVA (time × condition) results showed that fatigue increased significantly more at altitude than at sea level(F 1,7 = 5.73, p < .05, Eta2 = .45). Other unpleasant mood states also increased more during the hypoxic condition than the normoxic condition. Effects were moderate, although not statistically significant, for anger (Eta2 = .36), confusion (Eta2 = .24), depression (Eta2 = .29), and tension (Eta2 = .31). Vigor scores decreased more during the altitude ride (Eta2 = .25). An examination of mood dynamics indicated that increases in depressed mood followed an exponential increase in fatigue, rather than the other way around, and that once depressed mood was activated it was associated with increased anger, confusion, and tension and reduced vigor.

CONCLUSIONS

Findings lend support to the notion that, compared to sea level, performing intense exercise at altitude is associated with greater mood disturbance. Future research should investigate the interplay between mood dynamics and the type of coping strategies used by athletes during intense exercise.

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