Cancer-Induced Fatigue and Skeletal Muscle Wasting: The Role of Exercise

Abstract

Fatigue is the most frequently reported symptom by cancer patients. Many of these patients perceive fatigue as the most distressing symptom associated with their illness because it imposes limitations on their physical activity level. Skeletal muscle wasting, which occurs as part of cancer cachexia, is one of the mechanisms that contribute to fatigue. Cancer-induced skeletal muscle wasting may occur despite normal food intake and is not prevented by nutritional supplementation. Evidence suggests that endurance exercise ameliorates cancer-related fatigue. There is no compelling evidence to support that exercise-induced reduction in fatigue is related to preservation of muscle mass. Resistance exercise attenuates muscle wasting associated with a variety of catabolic conditions. However, its effects on cancer-induced muscle wasting have not been adequately studied. This article describes the physiological mechanisms implicated in the induction of cancer-related muscle wasting, summarizes findings from endurance and resistance exercise studies in relation to fatigue and muscle wasting during cancer and selected clinical conditions, and proposes directions for future research.

Cancer cachexia-anorexia syndrome and skeletal muscle wasting

“…72 The results of the study demonstrate that resistance training attenuates wasting of the extensor digitorum longus muscle (EDL) in tumor-bearing mice. This attenuation of wasting was paralleled by an increase in muscle weight, which was due to an increase in the actual mass of muscle and not merely due to edema.…”

Muscle mass as a target to reduce fatigue in patients with advanced cancer

“…Central effects of elevated cytokine levels (among which interleukin‐2, interleukin‐6, and tumour necrosis factor alpha) cause changes in activity of the hypothalamus‐pituitary‐adrenal axis, leading to a sensation of reduced capacity to perform physical work, but also to a reduced androgen expression 6, 8. Both pathways could result in a loss of muscle mass, but whether a decreased muscle mass itself affects CRF is unclear 4, 9…”

The development of an evidence-based physical self-management rehabilitation programme for cancer survivors

“…A decreased oxygen uptake or aerobic capacity may reflect the difficulty the cardio-respiratory system has in delivering oxygen throughout the body and/or problems of the musculoskeletal system in extracting oxygen from the blood during aerobic exercise. Both radiotherapy and chemotherapy appear to have negative side effects on the cardio-respiratory system [7,28] and on the musculoskeletal system [23]. Significant muscle wasting and consequent decreased muscle strength [29] affects about 50% of persons with cancer [4,23,30,31].…”