Muscle Strength and Activation as Determinants of Upper Extremity Exercise Capacity in Adolescent and Young Adult Patients with Pulmonary Arterial Hypertension

Purpose: Pulmonary arterial hypertension (PAH) impairs aerobic capacity due to combined cardiopulmonary and skeletal muscle dysfunction. However, upper extremity aerobic performance and its muscle-related correlates remain underexplored. This study aimed to examine the relationship between maximal workload achieved during an arm ergometer test and peripheral muscle parameters in adolescents and young adults with PAH.

Method: Sixteen PAH patients (mean age: 19.88±7.44 years; 9 females) were assessed. Maximal workload (watts) was measured via arm ergometry. Handgrip and shoulder abduction strength were recorded using dynamometers and normalized to percent predicted values. Fat-free mass (FFM) was estimated via bioelectrical impedance analysis. Surface electromyography (EMG) of the anterior deltoid was collected during the initial and final stages of the exercise and expressed as %Maximum Voluntary Isometric Contraction (MVIC) following SENIAM standards. Brain Natriuretic Peptide (BNP) values were retrieved from clinical records. Spearman correlation was used to assess associations.

Results: Maximal workload showed positive correlations with FFM (r = 0.615, p = 0.011), shoulder abduction strength (r = 0.535, p = 0.033), and handgrip strength (r=0.620, p=0.010). It was negatively correlated with BNP (r = –0.728, p = 0.005) and early-stage anterior deltoid EMG (%MVIC) (r = –0.602, p = 0.014). Final-stage EMG showed a non-significant negative trend (r = –0.442, p = 0.086).

Conclusion: Upper extremity aerobic performance in PAH is associated with muscle strength, mass, activation, and cardiac stress. Arm ergometry may serve as a functional indicator in this population.

Key Words: Upper Extremity, Motor Activity, Electromyography, Muscle Strength, Pulmonary Hypertension