Effects of unsupported arm training on arm exercise-related perception in COPD patients

Abstract

We hypothesized that arm training might affect unsupported arm exercise-related perception by decreasing motor output to arm/torso muscles in patients with chronic obstructive pulmonary disease (COPD). Eleven patients were studied at 80% of peak incremental arm exercise, before and after unsupported arm training. Training increased endurance time, decreased respiratory effort and much more arm effort (by Borg scale) without affecting chest wall dynamic hyperinflation or configuration. Ventilatory response to carbon dioxide output was the same before and after training so that at isotime the reduction in ventilation correlated strongly with a simultaneous reduction in metabolic output. These changes reflect a reduced ventilatory drive. We conclude that: (i) a reduced level of ventilation, relative to a decrease in central motor output, is the contribution of arm training to symptom alleviation during unsupported arm exercise in COPD patients, and (ii) arm training improved patients’ exercise-related perception without affecting chest wall operational volumes or configuration.

Introduction

Many patients with chronic obstructive pulmonary disease (COPD) complain of dyspnea during arm exercise. The increased demand during simple arm elevation may play a role in the development of dyspnea and in the limitation that is frequently reported by these patients when performing daily-life activities involving the arms (Celli et al., 1986, Tangri and Wolf, 1973). To limit dyspnea and arm fatigue, COPD patients often reduce the use of their arms during activities.

Upper extremity training is increasingly recognized as an important component of pulmonary rehabilitation (Ries et al., 2007). While arm ergometry may be best for measuring peak arm exercise capacity and endurance during supported arm exercise, the unsupported arm exercise (UAE) test may better reflect daily-life activity (Janaudis-Ferreira et al., 2012).

Although some studies have demonstrated improvement in UAE after upper extremity training (Holland et al., 2004, Janaudis-Ferreira et al., 2011, McKeough et al., 2005), suggesting that the test can be sensitive to changes in arm exercise capacity, the impact of upper extremity training on UAE dyspnea and arm fatigue remains unclear (Costi et al., 2009, Martinez et al., 1993, Neiderman et al., 1991, Ries et al., 1988) or undemonstrated (Costi et al., 2009, Couser et al., 1993, Janaudis-Ferreira et al., 2011, Lake et al., 1990).

Surprisingly, despite the discrepancy between respiratory patients’ self-reported dyspnea and the true extent of the pathophysiology, few studies (Costi et al., 2009, Couser et al., 1993, Janaudis-Ferreira et al., 2011, Martinez et al., 1993) have investigated the effect of upper extremity training on ratings of perceived dyspnea by applying psychophysical methods, that is, the quantitative study of the relationship between stimuli and the evoked conscious sensory response. Critical appraisal of symptoms can only come with application of psychophysical techniques applied within the framework of respiratory and sensory physiology (Killian et al., 1992). We based this study on sensory-perceptual measures which include real-time rating of intensity. We avoided using impact measures which, although very important, “do not directly assess what breathing feels like” (ATS, 2012). On this basis we have recently demonstrated that neither chest wall dynamic hyperinflation nor dyssynchronous breathing per se are the major contributors to dyspnea during either cycling leg exercise (Innocenti Bruni et al., 2012) or UAE (Romagnoli et al., 2011) in COPD patients. Using the same approach we tried to document the impact of unsupported arm exercise training (UAET) on UAE-related perceptions. The finding that patients stop UAE mainly because of arm effort prompted us to speculate that afferent information elicited by arm/torso muscles and conveyed to the motor-sensory cortex is perceived as a sensation of excessive arm effort (Romagnoli et al., 2011).

We therefore hypothesized that a decrease in ventilatory demand reflective of decreased central motor output might explain the salutary effects of UAET in patients with COPD.