Latissimus Dorsi Activation During Shoulder Extension Exercises

Condition(s) studied

Investigational drug(s) / intervention(s)

Exercise: Standing with the shoulder in \~30° abduction and external rotation and the elbow extended, participants elevate the arm to three preset flexion angles (30°,60°, 90°, 120°; measured by goniometer) and then perform shoulder extension past the trunk against color-coded elastic bands. Bands are anchored overhead and pulled diagonally downward; the band angle is adjusted to match each shoulder-flexion condition. Tempo is metronome-paced: 3 s concentric, 3 s isometric (at peak), 3 s eccentric. Resistance is individualized using the OMNI Perceived Exertion Scale and titrated until 6-8/10 is reached prior to data capture. Each condition is recorded for 3 repetitions with \~5 s between reps; \~2 min rest is provided between conditions. A brief familiarization (\~3 min per condition) is given, and the order of MVICs and exercise conditions is randomized.

Study summary

This observational, cross-sectional laboratory study at Hacettepe University will examine surface EMG activation of the latissimus dorsi during resisted, dynamic shoulder extension performed at three shoulder flexion angles (30°,60°, 90°, 120°). The primary objective is to quantify latissimus dorsi activation and to determine how elevation angle influences activation; secondary analyses compare synergists.

Eligibility

Primary outcome measure(s)

• Electromyography — Baseline (Day 1)
  Muscle activation will be assessed with an 8-channel surface EMG system (TeleMyo DTS, Noraxon). Following SENIAM, bipolar Ag/AgCl electrodes (2 cm inter-electrode distance) will be placed over medial and lateral latissimus dorsi, teres major, infraspinatus, posterior deltoid, and triceps brachii, secured with double-sided tape. Before exercise, MVICs will be obtained on the dominant arm by the same assessor (3 × 5 s with 30 s between trials and 2 min between muscles) using standardized, literature-based positions with verbal encouragement.The exercise protocol will consist of elastic-band resisted shoulder extension performed for three repetitions (3 s concentric-3 s isometric-3 s eccentric) with 5 s between repetitions and 2 min rest between conditions, while EMG from all target muscles is recorded and timing is controlled by a metronome.

Trial sites (1)

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