Improvements in muscle strength, power, and size and self-reported fatigue as mediators of the effect of resistance exercise on physical performance breast cancer survivor women: a randomized controlled trial

• Published in: Supportive care in cancer Vol. 28; no. 12; pp. 6075 - 6084
• Main Authors: Santagnello, Samarita Beraldo, Martins, Fernanda Maria, de Oliveira Junior, Gersiel Nascimento, de Freitas Rodrigues de Sousa, Jairo, Nomelini, Rosekeila Simões, Murta, Eddie Fernando Candido, Orsatti, Fábio Lera
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-12-2020; Springer; Springer Nature B.V
• Subjects: Aged; Body Composition - physiology; Breast cancer; Breast Neoplasms - complications; Breast Neoplasms - pathology; Breast Neoplasms - rehabilitation; Cancer Survivors; Clinical trials; Exercise; Exercise - physiology; Fatigue - etiology; Fatigue - therapy; Female; Humans; Leg; Medicine; Medicine & Public Health; Middle Aged; Muscle strength; Muscle Strength - physiology; Muscle, Skeletal - pathology; Muscle, Skeletal - physiology; Muscular system; Nursing; Nursing Research; Oncology; Organ Size; Original Article; Pain Medicine; Physical Functional Performance; Political aspects; Rehabilitation Medicine; Resistance Training; Self Report; Strength training; Survivor; Womens health; Muscle power; Self-reported fatigue; Breast cancer survivors; Muscle strength
• ISSN: 0941-4355; 1433-7339
• DOI: 10.1007/s00520-020-05429-6

Purpose
To gain more knowledge about the mechanism (i.e., mediators) of resistance exercise (RE)-induced improvements in physical performance (PP), we seek to investigate whether improvements in muscle strength (MS), muscle power (MP), and lean body mass (LBM) and (or) self-reported fatigue (SRF) are mediators of the effect of RE on PP in breast cancer survivor women (BCSW).
Methods
The volunteers were randomly divided into two groups: control group (CT;
n
 = 9) and resistance exercise (RE;
n
 = 11). The RE protocol consisted of three sets in each exercise (leg extension, leg curl, 45° leg press, and calf raise), between 8 and 12 repetitions per set, with an estimated load of 80% of one-repetition maximum (1RM), and three times a week on non-consecutive days for 12 weeks. The CT group performed only stretching exercises twice a week. SRF, maximal muscle power (Pmax), MP, LBM, and PP were assessed using the Brief Fatigue Inventory Questionnaire; 1RM test; isoinertial dynamometer; DXA; and walking speed, sit-to-stand (STS), and timed up and go (TUG) test, respectively.
Results
Following 12 weeks, the RE group reduced SRF and increased MP, Pmax, LBM, and performance in all tests (walking speed, STS, and TUG) when compared with the CT group. There were significant associations of the changes in LBM, MS, Pmax, and SRF with changes in physical performance tests only in the RE group.
Conclusion
Our findings suggest that improvements in LBM, MS, MP, and self-reported fatigue mediate the effect of resistance exercise on physical performance in BCSW.