The effect of chest wall restriction on exercise capacity

Objective: Subjects with restrictive pulmonary disease exhibit a decreased exercise capacity compared to non-diseased subjects, as do subjects in certain workplace situations, for example when wearing bullet-proof vests. The purpose of this study was to examine the effects of varying degrees of chest wall restrictive loading on exercise performance. We have designed and validated a chest wall restrictor that mimics the elastic loading occurring in some disease states and some occupational situations. Methodology: In this study, 18 subjects performed five graded maximal cycling tests while wearing the device at four different inflation pressures (0, 20, 40, and 60 mmHg). Results: Maximal values of oxygen uptake (V̇O₂max), minute ventilation (V̇₁max), tidal volume (V_T at max) and breathing frequency (f_B at max) were monitored, as was the time to maximal exercise (TTM). V̇O₂, V̇₁, V_T, and f_B were also measured at three submaximal loads. The results showed that V̇O₂max, V₁max, TTM, and V_T at max were significantly decreased, while f_B at max was maintained. At submaximal loads, the ventilatory parameters V_T, and f_B were altered with load, but V̇₁ and V̇O₂ were not affected by load. Conclusions: These results indicate that the wearing of this device decreases variables associated with maximal exercise, and that the decreases are related to the degree of chest wall restriction. Furthermore, submaximal exercise ventilation was minimally altered, with an increase in f_B and a decrease in V_T associated with increasing restrictive loads. Submaximal oxygen uptake was not affected by breathing restriction.