Moderators of the relationship between exercise and mood changes: gender, exertion level, and workout duration

Abstract

Although the role of exercise in improving mood is well established, less is known about moderators of this effect, particularly outside of the laboratory. The current study examined the effect of gender, type of exercise, level of exertion, and duration of workout on the exercise–mood relationship in a naturalistic setting. One hundred and thirty five participants (64 females) either engaged in weight training (n = 52) or cardiovascular (n = 83) exercise. Pre- and post-exercise assessments of mood were collected and changes in two types of mood, negative mood and exhaustion, were examined. Overall, participants reported improved mood after exercise in both domains. Workout duration and level of exertion significantly moderated the relationship of exercise to mood improvement (i.e., an increase in either corresponded to greater improved mood, ps<0.05). Overall, women showed more improved mood than men in the domain of exhaustion (p = 0.001).

Keywords:

• Exercise
• Mood
• Perceived exertion
• Gender

Notes

The literature on changes in plasma endorphin levels due to exercise and resultant mood changes is equivocal. Generally, beta endorphin levels have been found to increase during moderate to intense (i.e., 60–80% of Maximum Heart Rate; MHR) cardiovascular exercise, but not in lower intensity cardiovascular exercise (i.e., 40–60% of MHR; e.g., Kraemer et al., 1989; Goldfarb et al., 1998). Other studies have found that cardiovascular workouts at 80% of MHR led to decreases of beta endorphin (Kraemer et al., 1990). Typically, no gender differences in beta endorphin levels at pre- or post-exercise have been observed and the relationship between mood and beta endorphin levels has been similar for men and women. However, Kraemer et al. (1990) found that, while no relationship between beta endorphin levels and mood emerged in women, decreased beta endorphin led to improved mood in men. More commonly, researchers have reported a positive relationship between beta endorphin levels and enhanced mood resulting from cardiovascular exercise (e.g., Harte et al., 1995). In contrast to cardiovascular exercise, beta endorphin levels seem most commonly to decrease in response to resistance exercise (e.g., McGowan et al., 1993; Pierce et al., 1994). McGowan et al. (1993) observed no relationship between beta endorphin level and mood. The diverse findings in this area may result from difficulties in measuring endorphin levels. The endorphin hypothesis posits that endorphin levels in the brain should be positively related to mood. However, measuring CNS endorphin levels is a highly invasive procedure that would lead to physical and psychological changes itself (Yeung, 1996). The dominant approach to this problem has been to measure plasma, or peripheral, endorphin levels, which is much less invasive. Unfortunately, it is unclear whether plasma endorphin levels correlate well with CNS levels, making work in this area difficult to interpret.