Relationship Between Peripheral Muscle Structure and Function in Patients With Chronic Obstructive Pulmonary Disease With Different Nutritional Status

Abstract

The purpose of this study was to investigate the relationships between peripheral muscle structure (mass) and function (strength, endurance, and maximal aerobic capacity) in patients with chronic obstructive pulmonary disease (COPD) with different nutritional states. Thirty-nine patients (31 male) with moderate-severe COPD (63.5 ± 7.3 [SD] years) and 17 controls (14 male; 64.7 ± 5.5 [SD] years) underwent isokinetic (peak torque [PT]), isometric (isometric torque [IT]), and endurance strength (total work [TW]) measurements of the knee extensor muscles and a maximal cardiopulmonary exercise test to evaluate the maximal aerobic capacity (peak oxygen uptake [VO(2)] peak). Muscle mass (MM) was determined using dual-energy x-ray absorptiometry. Patients with COPD presented with reduced muscle function as compared with the healthy controls: PT (105.9 ± 33.9 vs. 134.3 ± 30.9, N·m(-1), respectively, p < 0.05), TW (1,446.3 ± 550.8 vs. 1,792.9 ± 469.1 kJ, respectively, p < 0.05), and VO(2)peak (68.1 ± 15.1 vs. 93.7 ± 14.5, % pred, respectively, p < 0.05). Significant relationships were found between muscle structure and function (strength and endurance) in the patient subgroup with preserved MM and in the control group: PT·MM(r(2) = 0.36; p = 0.01 vs. r(2) = 0.32; p = 0.01, respectively) and TW·MM (r(2) = 0.32; p = 0.01 vs. r(2) = 0.22; p = 0.05, respectively). Strength corrected for mass normalized this function in both patient subgroups, whereas endurance was normalized only in the patient subgroup without muscle depletion. Maximal aerobic capacity remained reduced, despite the correction, in both patient subgroups (depleted or nondepleted) compared with the healthy controls (VO(2)peak.MM: 9.1 ± 3.7 vs. 21.8 ± 4.9 vs. 28.5 ± 4.2 ml·min·kg, respectively, with p < 0.01 among groups). Muscle atrophy seems to be the main determinant of strength reduction among patients with moderate-severe COPD, whereas endurance reduction seems to be more related to imbalance between oxygen delivery and consumption than to the local muscle structure itself. Peripheral MM did not constitute a good predictor for maximal aerobic capacity in this population. The main practical application of this study is to point out a crucial role for the strategies able to ameliorate cardiorespiratory and muscular fitness in patients with COPD, even in those patients with preserved MM.

Handgrip and functional capacity in Chronic Obstructive Pulmonary Disease patients

“…On the other hand, our results meet the findings of those in the studies, that states that the muscular strength of the upper limbs of COPD patients can be preserved in the distal muscles, due to the fact that they are used in the daily activities, and reduced in the proximal muscles due to increased dyspnea during the activity sustained by the arm (18,19,20). However, studies highlight that there is a very strong correlation between the HGS and the strength of the other peripheral muscles, like the ones evaluated by the strength of the flexors of the elbow and the knee, as well as the respiratory muscle strength (maximal inspiratory muscle pressure and maximum voluntary ventilation) (15,21).…”

Microvascular oxygen extraction during maximal isometric contraction in patients with chronic obstructive pulmonary disease

“…The reduced contractile ef iciency could be justi ied by this lower lean mass, especially given the strong correlation observed in this study, (Fig 3) and the indings obtained in other studies conducted by this laboratory, in which strong correlations were observed between muscle mass of the lower limb with peak torque, isometric force and total work in patients with COPD (25,26). However, this scenario was characterized by less muscle mass (agent) and lower torque or generated work (product), which does not explain the increased O 2 extraction observed in this study (constant of proportionality: extraction O 2 ∝ agent ‹=› product).…”

Antagonistic implications of sarcopenia and abdominal obesity on physical performance in COPD

“…ASMI positively contributed to muscle strength, peak workload and CET (CET only in men), whereas A/G%FM positively contributed to muscle strength and 6MWD in men, but negatively to 6MWD in women. The better prediction of ASMI for muscle strength and peak workload as compared with CET and 6MWD can be attributed to the direct interaction between muscle mass and weakness in this population, whereas muscle endurance is suggested to be affected by multiple additional factors related to COPD [35]. Noticeable is the independent contribution of BMC to endurance in the regression model.…”