Chronic Effects of Resistance Training in Breast Cancer Survivors

Wanderson Divino Nilo dos Santos,Paulo Gentil, Rafael Felipe de Moraes, João Batista Ferreira Júnior, Mário Hebling Campos, Claudio Andre Barbosade Lira, Ruffo Freitas Júnior, Martim Bottaro, and Carlos Alexandre Vieira.

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Chronic Effects of Resistance Training in Breast Cancer Survivors

Wanderson Divino Nilo dos Santos,Paulo Gentil, Rafael Felipe de Moraes, João Batista Ferreira Júnior, Mário Hebling Campos, Claudio Andre Barbosade Lira, Ruffo Freitas Júnior, Martim Bottaro, and Carlos Alexandre Vieira.

Objective. To analyse effects of resistance training (RT) in breast cancer survivors (BCS) and how protocols and acute variables were manipulated. Methods. Search was made at PubMed, Science Direct, and LILACS. All articles published between 2000 and 2016 were considered. Studies that met the following criteria were included: written in English, Spanish, or Portuguese; BCS who have undergone surgery, chemotherapy, and/or radiotherapy; additional RT only; analysis of muscle performance, body mass composition (BMC), psycho social parameters, or blood biomarkers.

Results. Ten studies were included. PEDro score ranged from 5 to 9. Rest interval and cadence were not reported. Two studies reported continuous training supervision. All reported improvements in muscle strength, most with low or moderate effect size (ES), but studies performed with high loads presented large ES. Five described no increased risk or exacerbation of lymphedema. Most studies that analysed BMC showed no relevant changes.

Conclusions. RT has been shown to be safe for BCS, with no increased risk of lymphedema. The findings indicated that RT is efficient in increasing muscle strength; however, only one study observed significant changes in BMC. An exercise program should therefore consider the manipulation of acute and chronic variables of RT to obtain optimal results.

Main findings

  • They did not find an increase in the appearance or exacerbation of oedema with resistance training (RT) when compared to the control groups in any study reviewed.
  • Resistance training can potentially have an important role in the control of body composition, but surprisingly, the current systematic review found only one study that observed significant changes in body composition.
  • It does not seem plausible to suggest that resistance training promotes a clinically relevant reduction in body fat in BCS, nor is it possible to get insight into what RT protocol may be more suitable for that outcome.
  • This lack of results seems to be related to training intensity, since the reviewed studies reported that participants increased the load based on subjective perceptions of discomfort.
  • Participants were probably training at submaximal intensity.
  • Women with breast cancer who underwent chemotherapy showed a loss of muscle mass, mainly in the lower body.
  • RT is important both for maintenance and for increasing muscle mass in BCS, and it is an efficient tool to increase functional capacity.
  • The present review found important weaknesses in training protocols; for example, many studies did not report the rest interval between sets, movement velocity, supervision ratio, and whether the exercise was performed until muscle failure.
  • A study in older people reported that shorter rest intervals (1min) resulted in higher body composition and performance gains than longer rest intervals (4min).
  • Results also suggested that BCS may need rest intervals longer than 2 minutes to be able to fully recover; however, the chronic effects of recovery intervals on resistance training adaptations in BCS remain unknown.
  • Studies with a high supervision ratio presented a large effect size for muscle strength gain.
  • Studies should evaluate the effects of load, volume, rest intervals between sets, cadence (speed of execution), exercise choice and order, and training methods, on muscular adaptations in BCS so as to determine and consolidate the potential benefits of resistance training for this population.