Efeito da fadiga sobre as adaptações do treinamento de força em sobreviventes de câncer de mama

Abstract

Losses in muscle mass and strength, morphological changes, and impairments in physical performance are commonly observed in the aging process and also in some pathologies, such as breast cancer. These deficits can be improved with the practice of physical exer-cise, especially resistance training (RT). However, it is common for breast cancer survi-vors (BCS) to report fatigue (both sensation and performance), which compromises the performance of daily activities and worsens the quality of life. It is uncertain whether fatigue moderates RT adaptations in BCS. To clarify this gap, a clinical trial was condu-cted with 28 BCS (fatigue group - n 15 / non-fatigue group - n 13), aged 37 to 73, who underwent 12 weeks of RT. Fatigue (sensation) was assessed by the Cancer Fatigue Scale questionnaire and fatigue (performance) was assessed by maximum voluntary isometric contractions (MVIC) to calculate critical torque and w'. Mass (cross-sectional area of the vastus lateralis - CSA) and muscle function (dynamic and isometric strength, force-velo-city profile) and physical performance (chair stand test - CST, Timed Up and Go - TUG, and 400m walk test) measures were evaluated before and after the intervention. Descrip-tive analysis was performed to characterize the sample, a Generalized Linear Model was used to assess the effect of the intervention, and an independent t-test was used to calcu-late total volume, average loads, repetitions, and frequency. Our results showed a reduc-tion in fatigue (sensation) in both groups, regardless of the level of fatigue reported at the start of the intervention (p 0.022). For performance fatigue, there was an increase in cri-tical torque (p 0.022) and in the average of 60 contractions (p 0.056). We observed an increase in strength for 1RM (p 0.001), F0 (p 0.001), isometric (p 0.002), and improve-ment in TSL (p 0.007). Additionally, both groups increased CSA (p 0.016) and walking speed (p 0.003). There was an increase in maximum power (p 0.029) and a reduction in handgrip strength (p 0.039) in the fatigue group. Although frequency was lower in the fatigue group (p 0.038), the volume was equalized between both groups. We conclude that fatigue does not moderate RT adaptations in BCS.