The purpose of this study was to compare muscular activity of the posterior deltoid muscle during three typical aquatic physical conditioning activities. This interpretative case study involved a 23 year old elite swimmer and athlete. Muscular activity was measured with surface electromyography during swimming crawl at maximum speed, and also while performing horizontal shoulder abduction using elastic band and Hydro-Tone Bells resistance. During the maximum voluntary contraction, we observed what appeared to be meaningful differences between the percentage of muscular activation during the swimming activity and that observed during the elastic band and aquatic resistance exercises (18.72% vs. 74.84% and 65.46%, respectively). No meaningful differences were observed between the percentage of muscular activation for the elastic band and aquatic resistance exercises. Resistance exercises, both in and out of the water, produce more muscle activation and may be more efficient for improving muscular strength than sprint crawl swimming