Title: Acute Effects of Resistance Exercise in Men with Symptoms of Muscle Dysmorphia
Description: Introduction: This dissertation explored the acute effects of varying resistance exercise intensities in men with symptoms of muscle dysmorphia (MD). MD is a complex and disabling disorder; yet, despite the negative health effects MD can have, few treatment methods exist, with many barriers. Exercise has the potential to overcome many of the barriers to MD treatment and has shown to have positive effects in people with related disorders; yet, these effects have not been tested in men with MD. Methods: Twenty-one men were recruited and completed four on-site sessions. Sessions 1 and 2 included a battery of psychological and physiological measures. Sessions 3 and 4 were single sessions of moderate (70% of 10-RM) and high (100% of 10-RM) intensity RE in a counterbalanced order separated by at least 48-hours. Acute changes in body image, affective valence, perceived activation, perceived muscle size, and exercise enjoyment, were assessed before (PRE), during (MID), immediately after (POST), and 30-minutes after (DELAY) each session.

Results: Repeated measures analysis of variance (ANOVA) showed significant effects of time for state body image (F = 8.05, p < .01, η2 = .17), affective valence (F = 5.12, p = .01, η2 = .28), perceived activation (F = 48.47, p < .001, η2 = .79), perceived muscle size (F = 8.79, p < .01, η2 = .31), and exercise enjoyment (F = 6.84, p < .01, η2 = .15). There were significant effects of condition (i.e., intensity) for perceived activation (F = 9.13, p < .01, η2 = .19) only. There was a significant condition x time interaction for perceived activation (F = 3.49, p = .03, η2 = .22) and exercise enjoyment (F = 3.12, p = .05, η2 = .07). Post-hoc analyses revealed a significant increase in state body image during both sessions (ps > .05), but a significant decrease in state body image emerged from POST to DELAY (p < .05) during the moderate intensity session only. Additionally, during the moderate intensity session affective valence significantly decreased from MID and POST to DELAY (ps < .01).

There were no significant changes in affective valence at any time point during the high intensity session (ps > .05). During the moderate intensity session, perceived activation significantly increased from PRE to MID, and POST (ps < .01), but significantly decreased from PRE, MID, and POST, to DELAY (ps < .01). During the high intensity session, perceived activation significantly increased from PRE to MID (p < .01), and from PRE and MID, to POST (ps < .01). Also, during the high intensity session perceived activation significantly decreased from PRE, MID, and POST, to DELAY (ps < .01). Perceived muscle size significantly increased from PRE to POST (p < .01), and significantly decreased from POST to DELAY (p < .01). Further, results suggest that participants enjoyed the high intensity RE session significantly more compared to the moderate intensity session (p < .01). Conclusion: Results suggest that men with MD symptoms have a more favorable response to high vs. moderate intensity RE.

These results support the literature suggesting that RE intensity likely plays an important role in perceived body image and muscle size among men with MD symptoms. Further research testing the effects of different RE variables (e.g., frequency, duration) is warranted to establish an optimal RE protocol to maximize body satisfaction in this population.