Effect Of Different Rating Of Perceived Exertions On The Muscle Strength In Breast Cancer Survivors

Abstract

PURPOSE: To evaluate the effect of resistance training (RT) with a higher rating of perceived exertion (RPE) and lower RPE on the muscle strength of upper limbs in breast cancer survivors (BCS). METHODS: Twenty-six BCS women (age: 56.07 ± 6.94 years old; body mass: 68.32 ± 11.16 kg) undergoing hormonal therapy, performed eight weeks of RT once a week with high supervision ratio (one trainer per volunteer). RT protocol was three sets of 8 to 12 repetitions, with a 2-min rest interval between sets, until volitional muscle failure, on the bench press (BP). RPE scale (0-10) was assessed after each set. After eight weeks, the BCS were categorized into two groups using the average of RPE, lower than 7 (< 7) and higher than 7 (≥ 7). The muscle strength was assessed by the 10-repetitions maximum (10-RM) test on the BP, and then normalized by body mass (kg/BM). A repeated measurement ANOVA with the Bonferroni post hoc tests was used to examine differences between muscle strength changes. RESULTS: After eight weeks of RT, 12 women reported RPE < 7 (6.12 ± 0.56) and 14 women reported RPE ≥ 7 (7.78 ± 0.49). There was no difference found at baseline (p = 0.23): 10-RM normalized was 0.27 ± 0.06 and 0.24 ± 0.05, for RPE < 7 and RPE ≥ 7, respectively. BCS who reported lower or higher RPE improved their 10-RM by ∆ 19 ± 12 % and ∆ 23% ± 14% (p< 0.0001), respectively, and no difference was found between groups (p = 0.30). CONCLUSIONS: The improvement in muscle strength of BCS seems is not related to higher or lower RPE, both levels of effort generated similar gains. Suggesting that RPE is not the main factor for improving muscle strength in this population. Further studies analyzing the differences between upper and lower RPE in upper muscle strength are needed.