The Independent Effects of Strength Training in Cancer Survivors: a Systematic Review

Abstract

Cancer treatment is associated with adverse changes in strength, body composition, physical function, and quality of life. Exercise training reduces cancer incidence and mortality rates and may offset some of the treatment-related effects. To determine the independent effects of strength training (ST) on the effects of cancer treatment, an initial search was performed in March and then updated in November 2015. Additional articles were identified by scanning references from relevant articles. Studies using traditional ST on strength, body composition, aerobic capacity, functional assessments, and psychosocial parameters were included. Excluded studies had no objective strength measurement or combined ST with additional exercise. Mean and standard deviations from 39 studies across seven cancer types were extracted for main outcomes. ST-induced change scores with 95% confidence intervals were calculated and were evaluated with paired t tests, where appropriate. Twenty to fifty percent improvements in maximal strength were observed, indicating that the ST programs were effective. Physical function was also enhanced (7-38%), although gains were less consistent. Body composition and psychosocial changes were rare, with only a few changes in selected cancer types. As such, ST appears to promote benefits that may be specific to cancer types. Strength was the only consistent outcome that improved in all cancer survivors. However, these gains in strength are still of tremendous importance, given its impact on functionality and quality of life. Several practical considerations for exercise testing, training, and data reporting are presented for consideration to improve the overall depth of the field.

The Effect of Familiarization on the Reliability of Isokinetic Assessment in Breast Cancer Survivors

“…Likewise, cancer-related fatigue is a subjective sense of exhaustion not relieved by rest that, also, reduces overall functionality and physical performance [12,24,36], which can play a significant role on exacerbating the loss of muscle tissue commonly observed in cancer survivors [4]. Physical exercise interventions, such as strength training, have been proposed to improve muscle function, attenuating cancer-related fatigue and cancer-induced muscle wasting [17,31,32,38]. However, to assess the effect of training interventions, it is important to use reliable measurements to meaningfully detect changes, if indeed these changes have been promoted by training and not by motor learning from repeating testing [19].…”

“…Breast cancer is the most common type of cancer diagnosed in women globally [7]. Considering that breast cancer and its treatments can induce several physical impairments during and after treatment [27,33], muscle function plays an important role in overall functionality, risk of falls and quality of life of breast cancer survivors [17]. Therefore, many interventions have already been proposed to improve muscle function in breast cancer survivors, such as progressive strength training [15].…”

“…Strength training is the most effective training intervention to develop muscle strength, leading to a better overall functionality [17]. However, to assess the efficacy of strength training interventions, it is imperative to use an accurate and reliable method to measure muscle function [37].…”

Clinical Implementation of Exercise Guidelines for Cancer Patients: Adaptation of ACSM’s Guidelines to the Italian Model

“…The independent effects of strength training in cancer survivors are generally such that strength and to a lesser degree functionality may be increased. In general, maximal strength gains in cancer patients have been on average 20%-50% [5]. It is, therefore, recommended that adult cancer patients should do muscle-strengthening activities that are moderate or high intensity and involve all major muscle groups on two or more days a week, as these activities provide additional health benefits.…”

“…It is well documented that tumorgenesis and cancer treatment is associated with adverse physical and physiological changes leading to metabolic and functional modifications, inducing pathologies of the cardiac, pulmonary, neural, bone and skeletomuscular systems [2]. These alterations effect cardiorespiratory capacity (fitness), strength, body composition, and physical function including immune system integrity, peripheral neuropathy, and quality of life [3][4][5][6][7][8]. However, it is increasingly clear that prescribing exercise during and post-cancer treatment may mitigate many of these adverse changes (Table 1) by decreasing tissue inflammation contributing to tumorgenesis [9][10][11][12][13][14].…”