Exercises using the upper limbs hyperinflate COPD patients more than exercises using the lower limbs at the same metabolic demand.

BACKGROUND: Lower and upper body exercise are mandatory constituents of a rehabilitation programme for patients with COPD. However, it is not known how much these exercises may induce pulmonary dynamic hyperinflation (DH). OBJECTIVE: To evaluate the DH in patients with COPD exercising the upper and lower parts of the body at the same metabolic demand. METHODS: Sixteen patients aged 63 +/- 13 years and with a FEV1 of 1.5 +/- 0.7 L (41 +/- 11% pred) were studied. Patients initially performed a maximal exercise test with the arms using the diagonal movement technique. The lower limbs were exercised on a treadmill at the same metabolic demand. RESULTS: Inspiratory capacity decreased 222 +/- 158 ml (9.8%) after the upper body exercise (p < 0.0001) and 148 +/- 161 ml (7%) after exercise with the lower body (p = 0.0028) and a difference between the two groups was found (p < 0.05). There was no difference between resting IC before upper and lower limbs exercises (p = 0.8); increase in minute ventilation and in pulmonary ventilation in percentage of maximum voluntary ventilation and reduction of expiratory time were larger in the upper limbs exercise (p < 0.05). Dyspnea as measured by the Borg Scale was higher in the upper body (3.9 +/- 2.2) than in the lower body (2.3 +/- 1.3) at the end of the exercise (p = 0.033). Pulmonary ventilation and inspiratory capacity were correlated (p = 0.0001; r = 0.82). CONCLUSION: Exercise with the upper part of the body causes more DH and dyspnea than exercise with the lower part of the body at the same metabolic demand.

Superficial shoulder muscle co-activations during lifting tasks: Influence of lifting height, weight and phase.

This study aimed to assess the level of co-activation of the superficial shoulder muscles during lifting movement. Boxes containing three different loads (6, 12, and 18 kg) were lifted by fourteen subjects from the waist to shoulder or eye level. The 3D kinematics and electromyograms of the three deltoids, latissimus dorsi and pectoralis major were recorded. A musculoskeletal model was used to determine direction of the moment arm of these muscles. Finally an index of muscle co-activation named the muscle focus was used to evaluate the effects of lifting height, weight lifted and phase (pulling, lifting and dropping phases) on superficial shoulder muscle coactivation. The muscle focus was lower (more co-contraction) during the dropping phase compared to the two other phases (-13%, p<0.001). This was explained by greater muscle activations and by a change in the direction of the muscle moment arm as a function of glenohumeral joint position. Consequently, the function of the shoulder superficial muscles varied with respect to the glenohumeral joint position. To increase the superficial muscle coactivation during the dropping phase may be a solution to increase glenohumeral joint stiffness.