Latissimus Dorsi Activity During Different Exercises

Condition(s) studied

Investigational drug(s) / intervention(s)

Exercise: Participants will perform six standardized pulling tasks-inferior glide, low row, seated row, bent-over row, seated press-up, and body lifting-using a resistance band or body weight. Each exercise is done for 3 repetitions with \~5 s between reps and \~2 min between exercises. Resisted exercises follow a metronome-paced 3 s concentric / 3 s isometric / 3 s eccentric tempo; purely isometric tasks are held for 3 s. Load is individualized with the OMNI 0-10 scale and increased during up to 10 familiarization reps until perceived exertion reaches 6-8/10. Exercise order is randomized to minimize ordering effects.

Study summary

This single-visit, laboratory study will quantify latissimus dorsi activation during standardized band/body-weight exercises commonly used in rehabilitation (e.g., standing bent-over row, inferior glide, seated press-up, body-lifting). Healthy, physically active adults (18-40 y; Tegner ≥5) will perform three repetitions per exercise with metronome-paced phases (≈3 s concentric, 3 s isometric, 3 s eccentric), 5-s rest between repetitions and 2-min between exercises; load will be individualized to reach OMNI RPE 6-8. Surface EMG (TeleMyo DTS; Noraxon) will be recorded from the latissimus dorsi (medial and lateral) and selected synergists (teres major, infraspinatus, posterior deltoid, triceps); electrode placement will follow SENIAM recommendations. Signals will be band-pass filtered (20-500 Hz), rectified, RMS-smoothed with a 100-ms window, and normalized to %MVIC using standardized MVC tests; exercise/MVC order will be randomized to limit bias. The primary outcome is mean normalized EMG amplitude per exercise; secondary outcomes include peak amplitude and categorical activation levels (low ≤20% MVIC, moderate 21-40%, high 41-60%, very high \>60%). The study involves minimal risk (possible mild skin irritation under electrodes and transient post-exercise fatigue).

Eligibility

Primary outcome measure(s)

• Electromyography — Baseline (Day 1)
  Surface EMG from the latissimus dorsi (medial and lateral sites) will be recorded with an 8-channel system (TeleMyo DTS; Noraxon). Skin will be shaved and cleaned with 70% isopropyl alcohol; bipolar Ag/AgCl electrodes will be placed per SENIAM with a 2 cm inter-electrode distance (MLD \~lateral to T9; LLD \~4 cm inferior to the scapular inferior angle, midway between the spine and lateral trunk). A synchronized video (Logitech C920) will mark movement onset/offset and will be deleted after analysis (no copies kept). Signals will be normalized to %MVIC using three 5-s MVIC trials (30-s rest between trials; \~2-min between muscles) performed in standardized positions with verbal encouragement. The outcome is the mean %MVIC during the steady phase of each exercise.

Trial sites (1)

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