The time-constant of postexercise heart rate recovery (HRRτ ) obtained by fitting heart rate decay curve by a first-order exponential fitting has being used to assess cardiac autonomic recovery after endurance exercise. The feasibility of this model was not tested after resistance exercise (RE). The aim of this study was to test the goodness of fit of the first-order exponential decay model to fit heart rate recovery (HRR) after RE. Ten healthy subjects participated in the study. The experimental sessions occurred in two separated days and consisted of performance of 1 set of 10 repetitions at 50% or 80% of the load achieved on the one-repetition maximum test [low-intensity (LI) and high-intensity (HI) sessions, respectively]. Heart rate (HR) was continuously registered before and during exercise and also for 10 min of recovery. A monoexponential equation was used to fit the HRR curve during the postexercise period using different time windows (i.e. 30, 60, 90, … 600 s). For each time window, (i) HRRτ was calculated and (ii) variation of HR explained by the model (R(2) goodness of fit index) was assessed. The HRRτ showed stabilization from 360 and 420 s on LI and HI, respectively. Acceptable R(2) values were observed from the 360 s on LI (R(2) > 0.65) and at all tested time windows on HI (R(2) > 0.75). In conclusion, this study showed that using a minimum length of monitoring (~420 s) HRR after RE can be adequately modelled by a first-order exponential fitting.

INTRODUÇÃO: O exercício resistido (ER) é um tipo de exercício amplamente praticado, sendo recomendado para a manutenção ou aprimoramento da força e massa musculares e utilizado com fins estéticos e de saúde. Apesar disto, pouco se sabe sobre o impacto deste tipo de exercício sobre o controle autonômico cardíaco, tampouco da influência do grupamento muscular nesta resposta. OBJETIVO: Verificar a influência do grupamento muscular utilizado durante o ER, na recuperação da frequência cardíaca (REC-FC) pós-exercício. MÉTODOS: Participaram deste estudo 14 indivíduos do sexo masculino (27,4 ± 6,1 anos; 79,4 ± 10,4 kg; 1,77 ± 0,1 m; 10,5 ± 4,6 %G) experientes na prática de ER. O protocolo experimental constou da realização de teste e reteste de 1RM nos exercícios supino horizontal e meio agachamento para determinação da força dinâmica máxima e execução do número máximo de repetições a 80% de 1RM com avaliação da REC-FC durante um minuto pós-exercício. RESULTADOS: Os resultados encontrados indicam menor REC-FC nos 10, 20, 30 e 40 segundos após o exercício meio agachamento em comparação ao supino horizontal. CONCLUSÃO: Os achados confirmam a influência do grupamento muscular na resposta autonômica cardíaca pós-esforço, no ER.

-This study aimed to compare the perceived subjective exertion (PSE) and total load lifted in resistance exercises performed on stable platforms (SP) and unstable platforms (UP). Participants were 20 men (24.6 ± 3.4 years, 179 ± 0.1 cm, 80.6 ± 9.1 kg and 11.8 ± 3.4% fat). Each subject performed a 15 maximum repetition test in half squat exercises (soil and balance discs), pronated barbell row (soil and bosu) and biceps curl (soil and balance discs) in both conditions. PSE was measured using the OMNI-RES scale and the load lifted value (kg). To verify the normality of data, the Shapiro-Wilk test was used. Possible differences related to loads and PSE on the platforms were performed by the paired t test. Significance level of p <0.05 was adopted. No significant differences between PSE values on SP and UP were respectively observed in the half squat (8.2 and 8.5 / p = 0.8), pronated barbell row (8.4 and 8.4 / p = 0.7) and biceps curl (8.6 and 8.7 / p = 1.0). Higher load values on SP and UP were respectively found in half squat (83.9kg and 70.3kg / p <0.001) and pronated barbell row exercises (53.2kg and 48.6kg / p = 0.01) on SP. However, biceps curl showed dissimilar behavior (48.2kg and 47.4kg / p = 0.5). It was concluded that UP does not promote differences in PSE responses even working with smaller load or similar load. Key words: Instability; Perceived exertion; Resistance strength. (24,6 ± 3,4 anos, 179 ± 0,1 cm, 80,6 ± 9,1 Kg e 11,8 ± 3,4 PSE em PE e PI respectivamente, no meio agachamento (8,2 e 8,5 / p=0,8), remada curvada pronada (8,4 e 8,4 / p=0,7) e rosca bíceps (8,6 e 8,7 / p=1,0). Foram encontrados maiores valores de carga em PE e PI respectivamente, nos exercícios de meio agachamento (83,9kg e 70,3kg / p<0,001) e remada curvada pronada (53,2kg e 48,6kg / p=0,01) na PE. Em contrapartida, para a rosca bíceps não ocorreu o mesmo (48,2kg e 47,4kg / p=0,5 Resumo -Objetivou-se comparar a percepção subjetiva do esforço (PSE) e a carga total levantada nos exercícios resistidos em plataformas estáveis (PE) e plataformas instáveis (PI). Participaram do estudo 20 homens % de gordura). Cada voluntário realizou um teste de 15 repetições máximas nos exercícios meio agachamento (solo e discos de equilíbrio), remada curvada pronada (solo e bosu) e rosca bíceps (solo e discos de equilíbrio) em ambas as condições. Foram medidas a PSE através da escala de OMNI-RES e o valor da carga levantada (kg