Quantificação do equivalente metabólico associado ao treinamento misto em circuito em pessoas com histórico de acidente vascular encefálico

Abstract

Background: The value of 3.5 mL·kg⁻¹·min⁻¹ has been used as a reference for resting metabolic rate (RMR), being considered a metabolic equivalent of task (MET). However, individuals with a history of stroke may show reduced values, largely due to significant muscle mass loss. Considering physical exercise, such as mixed circuit training (MCT), as a fundamental practice in post-stroke rehabilitation, it seems relevant to understand if the estimated value of 3.5 mL·kg⁻¹·min⁻¹ is accurate for quantifying RMR, intensity, and energy cost associated with MCT. Objectives: To evaluate the MET and energy cost associated with a single MCT session performed by individuals with a history of stroke using estimated and measured values obtained through indirect calorimetry, as well as the test-retest reproducibility of these values. Methods: The sample consisted of seven patients with a history of stroke (58 ± 12 years) who underwent two RMR measurements and two MCT sessions (test-retest). The MCT consisted of 10 exercises (squats, step-ups, leg press, seated row, knee extensions, bench press, knee flexion, shoulder press, hip abduction, and bicep curls), each performed in 3 sets of 15-RM. Between exercises, participants completed a 45-second self-paced comfortable walk on flat ground. The MET for each exercise in the MCT was calculated by dividing the oxygen consumption during exercise by the estimated and measured RMR values (mL·kg⁻¹·min⁻¹). The energy cost of the MCT was calculated using the following equation: kcal·min⁻¹ = MET × body weight in kg × time in minutes ÷ 60. The Shapiro-Wilk test was used to test data normality, and results were presented as mean ± standard deviation (SD). Potential differences between estimated and measured values for RMR, MET, and energy cost were assessed using Student's paired t-test. The intraclass correlation coefficient (ICC) was calculated using a two-way random-effects model and single measures (ICC 2,1) to analyze the test-retest reproducibility of the dependent variables. Data were analyzed using SPSS® version 23 (SPSS™ Inc., Chicago, IL, USA). A significance level of P ≤ 0.05 (two-tailed) was adopted for all analyses.On average, the RMR of 2.6 mL·kg⁻¹·min⁻¹ was significantly lower than the reference value (mean difference = 0.9 mL·kg⁻¹·min⁻¹, 95% confidence interval, CI = 0.6 to 1.3 mL·kg⁻¹·min⁻¹, t = 6.5, P < 0.001). The intensity and energy cost values of the MCT sessions were significantly underestimated when derived from the predicted RMR value of 3.5 mL·kg⁻¹·min⁻¹ (P < 0.001). The average intensity of the MCT sessions based on measured RMR was 4.7 METs compared to 3.4 METs based on predicted RMR. The average measured energy cost was 219 kcal, significantly higher than the predicted value of 132 kcal (P < 0.01). Regarding test-retest reliability of the MCT sessions, the ICC 2,1 for METs and energy cost was excellent, ranging from 0.85 to 0.97. Conclusion: The reference value of 3.5 mL·kg⁻¹·min⁻¹ overestimates 1-MET representation in individuals with a history of stroke. This same reference value underestimated the intensity and energy cost of MCT sessions. The 1-MET value of 2.6 mL·kg⁻¹·min⁻¹ appears to be more appropriate