Is heart rate variability a feasible method to determine anaerobic threshold in progressive resistance exercise in coronary artery disease?

ABSTRACT Background Recent studies have shown that the magnitude of the metabolic and autonomic responses during progressive resistance exercise (PRE) is associated with the determination of the anaerobic threshold (AT). AT is an important parameter to determine intensity in dynamic exercise. Objectives To investigate the metabolic and cardiac autonomic responses during dynamic resistance exercise in patients with Coronary Artery Disease (CAD). Method Twenty men (age = 63±7 years) with CAD [Left Ventricular Ejection Fraction (LVEF) = 60±10%] underwent a PRE protocol on a leg press until maximal exertion. The protocol began at 10% of One Repetition Maximum Test (1-RM), with subsequent increases of 10% until maximal exhaustion. Heart Rate Variability (HRV) indices from Poincaré plots (SD1, SD2, SD1/SD2) and time domain (rMSSD and RMSM), and blood lactate were determined at rest and during PRE. Results Significant alterations in HRV and blood lactate were observed starting at 30% of 1-RM (p<0.05). Bland-Altman plots revealed a consistent agreement between blood lactate threshold (LT) and rMSSD threshold (rMSSDT) and between LT and SD1 threshold (SD1T). Relative values of 1-RM in all LT, rMSSDT and SD1T did not differ (29%±5 vs 28%±5 vs 29%±5 Kg, respectively). Conclusion HRV during PRE could be a feasible noninvasive method of determining AT in CAD patients to plan intensities during cardiac rehabilitation.

The reliability of the one maximum repetition in sedentary, active and strength-trained subjects / Reprodutibilidade de uma repetição máxima em sujeitos sedentários, ativos e treinados em força

The aim of the study was to verify the reliability of one maximum repetition (1-RM) in three different groups, according levels of physical fitness. The sample was composed for thirty subjects (aged 18 to 34 years old) divided in three groups with ten subjects each: sedentary (SG), physical active (PAG) and strength-trained (STG). The subjects were submitted to two familiarization sessions and two sessions of maximum strength test (1-RM1 and 1-RM2) at the following exercises: bench press and 45¨¬ leg press. The comparison between 1-RM values was made by two-way ANOVA (test and group) and association between both by intraclass coefficient correlation (p ¡Â 0.05). Data presented high correlation values between both tests (from 0.922 to 0.997; p < 0.001), however, significant differences (p < 0.05) was observed between 1-RM1 and 1-RM2 at bench press exercise in SG (56.40 ¡¾ 8.00 kg e 57.60 ¡¾ 7.89 kg, respectively), PAG (68,80 ¡¾ 9,26 kg e 69,40 ¡¾ 8,78 kg, respectively) and STG (87.20 ¡¾ 19.94 kg e 88.60 ¡¾ 19.86 kg, respectively), as well in the leg press in SG (222,5 ¡¾ 38,24 kg e 229,50 ¡¾ 38,55 kg, respectively), PAG (238.50 ¡¾ 26.25 kg e 244.00 ¡¾ 24.70, respectively) and STG (321.50 ¡¾ 46.19 kg e 336.40 ¡¾ 40.44 kg, respectively). It can be concluded that the subject¡¯s level of physical fitness does not appear to be a critical behavior at 1-RM reliability.

O objetivo deste estudo foi verificar a reprodutibilidade do teste de 1-RM em três diferentes grupos, conforme seu histórico de prática de exercícios. A amostra foi composta por trinta sujeitos (entre 18 e 34 anos): sedentários (GSE, n = 10), fisicamente ativos (GFA, n = 10) e treinados em força (GTF, n = 10) e foram submetidos a duas sessões de familiarização e a duas sessões de testes de força máxima (1-RM1 e 1-RM2) nos exercícios supino reto e pressão de pernas 45¡Æ. Foi utilizado a ANOVA two-way (teste e grupo) e o teste de correlação intra-classe (p < 0,05). Verificaram-se altos valores de correlação entre os testes (de 0,922 a 0,997; p < 0,001), contudo, diferenças significativas (p < 0,05) foram encontradas entre 1-RM1 e 1-RM2 no exercício supino para o GSE (56,40 ¡¾ 8.00 kg e 57,60 ¡¾ 7,89 kg, respectivamente), GPA (68,80 ¡¾ 9,26 kg e 69,40 ¡¾ 8,78 kg, respectivamente) e GTF (87,20 ¡¾ 19,94 kg e 88,60 ¡¾ 19,86 kg, respectivamente), assim como no exercício pressão de pernas para o GSE (222,5 ¡¾ 38,24 kg e 229,50 ¡¾ 38,55 kg, respectivamente), GPA (238,50 ¡¾ 26,25 kg e 244,00 ¡¾ 24,70 kg, respectivamente) e GTF (321,50 ¡¾ 46,19 kg e 336,40 ¡¾ 40,44 kg, respectivamente). Logo, pode-se concluir que o perfil do histórico de prática de exercícios dos sujeitos parece não ser um fator decisivo no comportamento da reprodutibilidade dos testes de 1-RM.