Effects of Aerobic Exercise Training on Peak Aerobic Capacity, Fatigue, and Psychological Factors During Radiation for Breast Cancer

Rehabilitation Oncology, 2005 by Drouin, Jacqueline S, Armstrong, Holly, Krause, Shawn, Orr, Jennifer, Et al

ABSTRACT

Background and Purpose: Pilot to determine aerobic exercise effects (AE) on peak aerobic capacity (peak VO^sub 2^), fatigue, and psychological factors during radiation. Subjects: 20 sedentary females (50.0 ± 8.0 years) with Stage 0-III breast cancer. Methods: Following human subject approval and informed consent, participants were randomly assigned to moderate intensity aerobic exercise (AE) or placebo-stretching (PS) condition during 7 weeks of radiation. Pre- to posttests were peak VO^sub 2^ using oxygen uptake analysis, Profile of Mood States (POMS), and Revised-Piper Fatigue Scale (R-PFS). Wilcoxon-Signed Rank Test assessed pre/post differences; Spearman's Rho assessed correlations (P ≤ .05). Results: AE peak VO^sub 2^ (P = .01), POMS anger-hostility (P = .02), depression-dejection (P = .02), and R-PFS affective meaning (P = .02) improved significantly. Peak VO^sub 2^ correlated with POMS fatigue-inertia (P = .04), angerhostility (P = .02), depression-dejection (P = .01), tension-anxiety (P = .04) and R-PFS sensory (P = .040). Discussion and Conclusions: Moderate intensity aerobic exercise is effective during radiation for breast cancer to increase peak VO^sub 2^ and therefore aerobic capacity reserves which relates to improved physical function. Changes in peak VO^sub 2^ are also related to improvements in fatigue and psychological factors during this time.

INTRODUCTION

Radiation has been shown through randomized controlled trials to improve locoregional control in women with breast cancer and appears to improve survival rates in both pre- and postmenopausal females when combined with other treatments that include surgery, chemotherapy, and hormonal therapies.1 However, women undergoing radiation treatment for breast cancer commonly experience debilitating side effects that include fatigue, mood disturbances, and diminished physical function.2,3 These side effects interfere with daily activities such as self-care, household management, and vocational and recreational pursuits.4 Aerobic exercise has been reported to improve these conditions; however, there is limited physical evidence to describe or explain possible mechanisms behind this phenomenon.5-7 Physical therapists and health care professionals would benefit from data that measures and describes changes in physiological measures resulting from training in order to explain and support this technique as well as to guide the development of safe and effective training protocols during radiation for breast cancer.

LITERATURE REVIEW

The most common complaint in females undergoing radiation for breast cancer is fatigue followed by depression.4 Depression appears to magnify symptoms of fatigue since a natural response to feeling depressed is to discontinue participation in physical activities leading to further physical deconditioning.3,4,8,9 Physical deconditioning lowers aerobic capacity reserves, which is the energy available for physical function, and this contributes to a more rapid onset of fatigue during physical activity.8,10 Furthermore, when people with cancer complain of fatigue, health care professionals often recommend decreasing participation in physical activities and additional rest.11,12 Over time, this leads to further deconditioning, greater reductions in maximal aerobic capacity, and diminished ability to tolerate normal activity.10,11

In 1987, Crews and Landers used a meta-analytic technique to investigate the relationship between aerobic fitness and responses to psychosocial stressors using 34 studies with a total of 1.449 apparently healthy subjects.13 Their analysis found that individuals who participated in aerobic exercise training improved their maximum aerobic capacity measures and also experienced significant reductions in their responses to psychosocial stressors compared to their baseline values and compared to values of nontrained control groups.

In 1997, Mock and colleagues studied the effects of aerobic exercise training on physical function, fatigue, emotional distress, and difficulty sleeping in 46 females undergoing radiation therapy for breast cancer.14 Study participants were randomly assigned to an exercise or a usual care group. Exercise consisted of self-paced, home-based walking, 4 to 5 days per week during a 6-week radiation regimen. Fatigue was measured using the Piper Fatigue Scale, and emotional distress was examined by means of the Symptoms Assessment Scale. Physical fitness was assessed using the distance covered during a '12-Minute Walk Test' and by a '0-10 Exercise Rating Scale' that was a self-report of an individual's time spent exercising. Following the intervention, the walking group had significant improvements on their reported measures of fatigue, anxiety, physical function, and difficulty sleeping, but not depression. The reported time spent exercising and change in the distance covered on the '12 Minute Walk Test' were significantly better in the exercise group compared to the control group. Significant negative correlations were also found between walking and fatigue (r = -.45; P