Effects of Ultrasound-Guided Percutaneous Neuromodulation on Shoulder Muscle Strength in CrossFit Athletes: A Pilot Randomized Controlled Trial.

Abstract

Background: CrossFit integrates diverse functional movements to optimize overall fitness, with muscle strength training being a core component. Ultrasound-guided percutaneous neuromodulation (US-guided PNM) has emerged as a potential adjunct to enhance muscle strength gains; however, its efficacy in the upper limb in healthy individuals remains unexplored.

Objective: This study evaluated the efficacy of two US-guided PNM protocols (three sessions and one session) targeting the axillary and suprascapular nerves in improving shoulder muscle strength in healthy CrossFit athletes.

Materials and methods: A pilot, randomized, controlled, single-blind clinical trial was conducted with 39 healthy CrossFit athletes randomly allocated to one of three groups: control (G1, no intervention), one session of US-guided PNM (G2), or three sessions of US-guided PNM (G3). Shoulder muscle strength was assessed using a hand-held dynamometer to measure external and internal rotation muscle strength at various shoulder positions before each treatment session (days 1, 7, and 14) and one week after the last session (day 21). Moreover, the one-repetition maximum (1RM) shoulder press exercise was evaluated on day 1 and day 21.

Results: No statistically significant differences were observed among groups for any outcome. However, the within-group analysis indicated statistically significant improvements over time in the treated limbs of intervention groups (G2 and G3), whereas no statistically significant changes were observed in the control (G1) or the untreated limbs of G2 and G3. The improvements were more consistent for shoulder strength measured in the neutral position than at 90° abduction.

Conclusions: Although US-guided PNM did not yield significantly greater improvements than did the control group, both one and three sessions targeting the axillary and suprascapular nerves enhanced rotational shoulder muscle strength in treated limbs and 1RM shoulder press performance. These findings should be interpreted with caution, and further investigation is warranted, particularly in populations with lower baseline strength and in exploring varied application parameters to optimize efficacy.

Clinical trial registration: The Clinicaltrials.gov registration number for the study is NCT06529770.