Does limb partitioning and positioning affect acute cardiorespiratory responses during strength exercises in patients with COPD?
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BACKGROUND AND OBJECTIVE: Cardiorespiratory responses and symptoms in response to endurance exercise in patients with COPD vary with the number and position of involved limbs. Responses to such variations have never been quantified for strength exercises. We therefore assessed acute cardiorespiratory responses during brief bouts of weight lifting exercises. METHODS: We compared double- versus single-limb leg extensions and arm elevations, as well as arm elevation done above or below shoulder level in patients with moderate to severe COPD (n = 10, 6 males, 66 (8.1 years), forced expiratory volume on 1 s (FEV1 ) % predicted = 34% (14%)). Minute ventilation, oxygen uptake, oxygen saturation, heart rate (HR), blood pressure (BP), rate of perceived exertion (RPE) and recovery time were collected during single sets of each exercise (10 repetitions at 80% of one repetition maximum). RESULTS: Ventilatory and gas exchange responses were not affected by the number of exercising limbs. Changes in HR, BP and RPE scores during arm elevation above shoulder level were greater after double- compared with single-arm elevation (P ≤ 0.001) and greater when exercising above compared with below shoulder level (P ≤ 0.01). Double-arm elevation above shoulder level required 1.5 min longer HR recovery time (P ≤ 0.041) compared with other exercises. CONCLUSION: Double-arm elevation above shoulder level appears to be more challenging than other strength exercise variations. Partitioning exercises and limb position may reduce perceived exertion during training.