ABSTRACT Contrary to original findi...

ABSTRACT

Contrary to original findings that attributed improvements in exercise capacity solely to psychological adaptations, physiologic adaptations to exercise have also piercing shown in patients with mild to morose COPD. Skeletal muscle is an adaptable tissue and exhibits a response to training in these patients similar to that of healthy individuals. Whole material part endurance training studies demonstrate reductions in lactic acidosis with exercise, improvements in oxidative enzyme and metabolism of muscle, and improvements in muscle vigor of the lower extremity. Although small in number resistance training studies are available, preliminary findings present to view an increase in upper and lower corpse muscle strength, muscle cross-sectional area, and an added benefit to aerobic training. events to come studies on skeletal muscle adaptation should use training protocols that vary in intensity and duration to target the specific abnormalities rest in skeletal muscle of patients with COPD

INTRODUCTION

Exercise training is a key-note component in the rehabilitation of patients with chronic obstructive pulmonary disease (COPD) and has been associated with increased functional capacity and improvements in quality of life.1 The mechanism by way of which tolerance for exercise is increased in consequence of training is multifactorial and includes the two psychological and physiological factors.2 Early studies in succession exercise training in COPD used subdued intensity training programs and conclud that patients with COPD were unable to exercise to an adequate intensity to induce a physiologic training power They concluded that any observ increase in exercise tolerance was to be ascribed to psychological factors such as desensitization to dyspnea, increased motivation, reduc anxiety, and also to improved efficiency of motion This was further substantiated at the fact that exercise training did not end in any changes in pulmonary function (eg airflow limitation) which was notion to be the only physiologic limitation to exercise in this population.3

Further studies have demonstrated that dyspnea may not be the one limitation to exercise in patients with COPD Leg fatigue has been reported as a general symptom limiting exercise in these patients with up to 30%-40% of patients with moderate to cruel disease reporting it as the main limiting factor to maximal period exercise.4,5 The presence of contractile fatigue of the quadriceps has been demonstrated in 60% of patients with COPD following maximal period exercise.6 Further support for skeletal muscle function as a limitation to exercise tend hitherwards from correlational studies where isometric power of the quadriceps has been correlated to maximal exercise capacity in succession a cycle ergometer (r = 065) and to the distance overlayed during a Six Minute Walk exhibition (r = 0.61) in this patient population.7

A growing corpse of evidence suggests that the skeletal muscle of patients with COPD demonstrates abnormalities in comparison to healthy age- and weight-matched rule subjects. The limb muscles of these patients exhibit a reduced oxidative capacity demonstrated by means of a reduced proportion of symbol I fibers, smaller cross-sectional area of sign I and IIa fibers, reduc concentration of oxidative enzyme and a lower capillary density.8 In addition, the muscle cross-sectional area measured using CT also is significantly reduc in comparison to healthy controls9 A number of contributing factors have been identified including inactivity, altered relations gases, nutritional depletion, electrolyte imbalance, systemic inflammation, and oxidative stress810

Exercise training is an intervention that can overset many of the changes seen in muscle of patients with COPD In healthy young and older adults, endurance training can end in muscle adaptations such as increased mitochondrial density and concentration of oxidative enzyme improved capillary density, and transformation of image IIb to Type Ha fibers.11 Resistance training can accrue in increased muscle strength and increases in muscle cross-sectional area.12 The final cause of this paper is to review the literature onward skeletal muscle adaptation as a rise of whole body endurance training and resistance training programs in patients with COPD Skeletal muscle in this paper directs only to muscles of the upper and lower extremity and not to muscles of respiration.

WHOLE material substance ENDURANCE TRAINING

Evidence for skeletal muscle adaptations to whole carcass endurance exercise can be arrangeed as follows: indirect evidence including reductions in lactic acidosis with exercise and direct evidence including changes in oxidative enzyme muscle bioenergetics, and improvements in measures of skeletal muscle performance (eg puissance endurance, and fatigue). Evidence from each of these 3 areas will be discussed. Table 1 provides details in succession subject characteristics and training protocols for these studies.

Indirect Evidence: Reductions in Lactic Acidosis

The lactate entrance also called the anaerobic entrance (AT), is associated with a disproportionate increase in concentration of serum lactate during incremental exercise. The AT is the arise of an increasingly greater connection on anaerobic metabolism by the working muscle and generally offers at high levels of exercise intensity; approximately 80% to 85% of VO^sub 2^max in healthy individuals.11 It was previously reflection that individuals with COPD were unable to exercise to an adequate intensity to reach their AT. However, a close attention by Sue et al13 reliably exposeed the onset of the AT at depressed levels of incremental exercise in two-thirds of patients with moderate to strait-laced COPD. This suggests an increased reliance in succession anaerobic metabolism in patients with COPD and is in keeping with the histochemical and morphological changes seen in (heir skeletal muscle. This finding l to further investigation to determine whether increases in lactate concentration with exercise could be attenuated with high intensity exercise training. A reduction in the concentration of lactate could be indicative of skeletal muscle adaptation (ie, improved oxidative capacity of muscle). brace well-designed studies have been done in this area and are discussed below.