Critical power for the upper limb in patients with chronic obstructive pulmonary disease: A pilot study

To investigated the impact of the ventilatory constraints in the power-duration relationship for upper limbs exercise in patients with chronic obstructive pulmonary disease (COPD).

Eight patients with COPD and eight healthy subjects performed an arm incremental test on cycle ergometer and four constant workload tests (100%, 90%, 80% and 70% of peak workload). The power-duration (or critical power - CP) estimative was determined. The inspiratory capacity was measured before and after each test.

There was no significant difference in the CP between patients and controls. Also, the curvature constant (W_AT, work do able above CP) was similar between patients and control subjects. Finally, the limits of tolerance for all constant workload tests in the patients with COPD were closely associated with the presence of dynamic hyperinflation and ventilatory reserve.

Despite patients typically showed more ventilatory stress compared with control subjects, the ventilatory constraints did not limit the sustained upper limbs exercise at the critical power.