Evaluation of resistance training to improve muscular strength and body composition in cancer patients undergoing neoadjuvant and adjuvant therapy: a meta-analysis

Muscle atrophy and strength decline are two of the most prominent characteristics in cancer patients undergoing cancer therapy, leading to decreased functional ability and reduced quality of life. Therefore, the aim is to systematically review research evidence of the effects of resistance exercise (RE) on lower-limb muscular strength, lean body mass (LBM), and body fat (BF) in cancer patients undertaking neoadjuvant or adjuvant therapy. This research was conducted using the following online database: Clinical Trial Register, Cochrane Trial Register, PubMed, SPORT Discus, and SciELO, from September 2014 until May 2015. We used the following keywords in various combinations with a systematic search: "Cancer therapy," "Wasting muscle," "Muscle loss," "Muscle function," "Neoadjuvant therapy," "Adjuvant thera-py," "Resistance Training," "Weight training," and "Exercise." After selection of 272 full-text articles, 14 publications were included in this meta-analysis. Resistance exercise (RE) during neoadjuvant or adjuvant therapy increased lower-limb muscular strength (mean: 26.22 kg, 95% CI [16.01, 36.43], heterogeneity: P = < 0.01, I (2) = 76%, P = 0.00001) when compared to controls over time. Similarly, lean body mass (LBM) increased (mean 0.8 kg, 95% CI [0.7, 0.9], heterogeneity: P = 0.99, I (2) = 0%, P < 0.00001), and decreased body fat (BF) (mean: -1.3 kg, 95% CI [-1.5, 1.1], heterogeneity: P = 0.93, I-2 = 0%, P < 0.00001) compared to controls over time. RE is effective to increase lower-limb muscular strength, increase LBM, and decrease BF in cancer patients undergoing neoadjuvant and adjuvant therapy regardless of the kind of treatment. RE increases muscle strength, maintains LBM, and reduces BF in cancer patients undergoing adjuvant and neoadjuvant therapies. Cancer patients and survivors should consider undertaking RE as an effective countermeasure for treatment-related adverse effects to the musculoskeletal system.