Objective: To explore associations between subjective GMax contraction and surface EMG (sEMG) of GMax, hamstrings (HS), and lumbar extensors (LE) during a standardized hip-extension task.

Background: Aerobic, resistance, and balance training benefit Parkinson’s disease (PD), yet individualized exercise prescriptions remain limited. Clinically, reduced hip extensor function may impair gait propulsion and stability. During gluteus maximus (GMax) training, PwP often show hamstring cramping or lumbar compensation, and the symptom-dominant side may have a reduced “sense of contracting.” Few studies have examined subjective contraction sense alongside objective muscle activity during targeted GMax tasks.

Method: Prospective pilot study in four women with PD (Hoehn & Yahr 1–2). Task: quadruped hip extension with slight knee flexion; raise to end-range, hold 5 s, five repetitions per side (medication ON). Bilateral sEMG was recorded from GMax, HS, and LE (normalized when feasible), and hip extension angle was measured. After each set, participants rated symptom-dominant GMax contraction on a 10-point VAS (non–symptom-dominant side = 10). Adverse events were monitored.

Results: All sessions were completed safely. Hip extension angle was smaller on the symptom-dominant side. sEMG often showed relatively higher LE activity on that side, while GMax and HS amplitudes varied across individuals. Subjective contraction sense on the symptom-dominant side was ≤6/10 in all participants. Exploratory analyses did not show a consistent correlation between VAS ratings and single-muscle amplitudes or simple activity ratios, likely due to small sample size and heterogeneous compensation patterns.

Conclusion: Targeted GMax training in PD revealed reduced contraction sense and hip extension with lumbar compensation on the symptom-dominant side. Given high inter-individual variability, strengthening programs should address asymmetry and compensations using technique cues, posture modifications, and graded progressions to improve selective GMax recruitment. Larger longitudinal studies integrating perception, sEMG selectivity, and kinematics are warranted.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/exploring-sense-of-muscle-contraction-during-gluteus-maximus-training-in-parkinsons-disease-a-preliminary-emg-perception-study/