Establishing Accessory Muscle Activation in Healthy Individuals During a Graded Exercise Test

Abstract

Introduction: Hyperinflation impairs diaphragm function and presumably places increased demands on accessory respiratory muscles in people with COPD. The purpose of this study was to develop a new application of electromyography(EMG) to assess accessory muscle activation and apply it during a graded exercise test(GXT).

Methods: Muscle activation, ventilatory parameters and dyspnea were collected from twenty participants during the GXT. The ratio between the inspiratory muscle activation during exercise and maximal muscle activation was used to quantify activation.

Results: Accessory muscle activation progressively increased during the GXT with the amplitude of scalenes exceeding that of the sternocleidomastoid (maximal activation 29.5% and 12.7%(%MVIC), respectively). Activation was moderately associated with IRV and weakly with dyspnea.

Conclusion: Healthy individuals who fail to achieve a VO2MAX used minimal accessory muscle activation to increase ventilation. These findings lay the groundwork to investigate accessory muscle activation in individuals with COPD and assess the benefits of interventions.