Impact of rescuer position, arm angle, and anthropometric variables on muscle fatigue during cardiopulmonary resuscitation: an international multicentric randomized crossover simulation study

Abstract

Background: There is a lack of studies using surface electromyography (sEMG) to objectively assess the impact of rescuer position and arm angle on muscle fatigue during CPR. Additionally, the relationship between anthropometric variables (height and weight) and muscle fatigue remains underexplored.

Aim: This study aims to objectively assess muscle fatigue during CPR by analyzing triceps brachii sEMG activation during continuous chest compressions (CCs) across different rescuer positions and arm angles. A secondary objective is to examine correlations between anthropometric variables and muscle fatigue, while also evaluating the impact of CCs quality on fatigue levels.

Methods: This international, multicentric, randomized crossover simulation trial included healthcare professionals assigned to one of four rescuer positions: kneeling on the floor, standing, standing on a step stool, and kneeling on a bed. Participants performed two 3-minute trials of continuous CCs at 90° and 105° arm angles. Muscle fatigue was assessed via sEMG, while compression quality was evaluated using manikin-derived data.

Results: A total of 72 participants were included. The 105° arm angle significantly increased muscle fatigue compared to 90° (p < 0.001) across all rescuer positions. Taller and heavier rescuers exhibited lower fatigue for both arm angles (p < 0.05); however, fatigue levels were consistently higher at 105° than at 90°.

Conclusion: Arm angle is a key determinant of rescuer muscle fatigue, with 105° increasing fatigue compared to 90°. Rescuer position alone was not significant, though fatigue was more pronounced in kneeling and elevated positions. Taller and heavier rescuers demonstrated greater endurance but remained affected by suboptimal arm angles.

Keywords: Anthropometric variables; Arm angle; Cardiopulmonary resuscitation; Chest compressions quality; Rescuer fatigue; Rescuer position; Surface electromyography.

Fig. 1

Participant flow diagram. Group 1: kneeling on the floor; Group 2: standing beside a bed; Group 3: standing on a step stool; and Group 4: kneeling on the bed.

Fig. 2

Boxplot representation of the AUC of iMDF per arm angle and across all rescuer positions. Left panel − all participants; Right panel – participants with high quality CCs. OCS – Overall compression score.

Fig. 3

Correlations between AUC of iMDF and anthropometric variables, for both arm angles. Left panels − all participants; Right panels – participants with high quality CCs at both arm angles. Lines represent the linear regression curves fitted to the data. OCS – Overall compression score.