Published Paper Details:

Context: The double-handed backhand (DHB) is a fundamental stroke in modern tennis, executed from a variety of stances, primarily "square" and "open." While the biomechanical implications of stance have been explored in the forehand, the specific demands on the trunk musculature during a DHB remain less understood. The trunk is critical for power generation and transfer. Objective: This study aimed to quantify and compare the muscle activation patterns of key trunk muscles - bilateral rectus abdominis (RA), serratus anterior (SA), and erector spinae (ES) - between the open and square stance DHB drives in skilled players. Methods: A total of 15 university-level tennis players (N = 15) participated in a repeated-measures, within-subjects study. Muscle activation was recorded using surface electromyography (sEMG) from six targeted muscles. Each participant executed a series of double-handed backhand (DHB) drives delivered by a ball machine under two stance conditions: (1) traditional square stance and (2) modern open stance. For each stroke, mean integrated EMG (iEMG) values were computed for the execution phase and normalized. Differences in muscle activation between stance conditions were analyzed using paired-samples t-tests. Results: The square stance DHB elicited significantly higher levels of muscle activation (p < 0.001) in the bilateral rectus abdominis (Right RA: +45.5%; Left RA: +49.5%) and the bilateral erector spinae (Right ES: +10.7%; Left ES: +8.5%) compared to the open stance. Conversely, the serratus anterior muscles showed a minor, non-significant trend (p > 0.05) towards higher activation in the open stance. Conclusion: Stance selection during the double-handed backhand was shown to have meaningful biomechanical and physiological implications. The square stance placed greater demands on both anterior and posterior trunk-stabilizing muscles, contrasting with prior findings on forehand strokes. These results suggest that the bilateral nature of the DHB produces distinct trunk recruitment patterns. Such evidence underscores the importance of incorporating stance-specific considerations into coaching pedagogy and strength and conditioning programs.