Physiological comparison of intensity‐controlled, isocaloric intermittent and continuous exercise^†

Abstract

VO2 fluctuations are argued to be an important mechanism underpinning chronic adaptations following interval training. We compared the effect of exercise modality, continuous vs. intermittent realized at a same intensity, on electrical muscular activity, muscular oxygenation and on whole body oxygen uptake. Twelve participants (24 ± 5 years; VO2peak: 43 ± 6 mL· min·kg) performed (i) an incremental test to exhaustion to determine peak work rate (WR); two randomized isocaloric exercises at 70%WRpeak; (ii) 1 bout of 30 min; (iii) 30 bouts of 1 min work intercepted with 1 min passive recovery. For electromyography, only the CON exercise showed change for the vastus lateralis root-mean-square (+6.4 ± 5.1%, P < .01, 95%CI 3.2, 8.3) and mean power frequency (-5.2 ± 4.8, P < .01, 95%CI -8.2, -3.5). Metabolic fluctuations (i.e. Oxygen Fluctuation Index and HHb Fluctuation Index) were higher in the intermittent modality, while post-exercise blood lactate concentrations (4.80 ± 1.50 vs. 2.32 ± 1.21 mM, respectively, for the CON and INT, P < .01, 95%CI 1.72, 3.12) and the time spent over 90% of VO2 target (1644 ± 152 vs. 356 ± 301 sec, respectively, for the CON and INT, P < .01, 95%CI 1130, 1446) were higher in the continuous modality. In conclusion, despite a similar energy expenditure and intensity, intermittent and continuous exercises showed two very different physiological responses. The intermittent modality would lead to a larger recruitment of fast twitch fibres that are less mitochondria-equipped and therefore may be more likely respondent to mitochondrial adaptations. In addition, this modality induces greater metabolic variations, a stimulus who could lead to mitochondrial development.

Muscle Fatigue in the Three Heads of Triceps Brachii During Intensity and Speed Variations of Triceps Push-Down Exercise

“…The RMS of sEMG signals is considered an important indicator of muscle activation and has been used by numerous researchers (Christie et al, 2009;Sakamoto and Sinclair, 2012). In addition to the aforementioned temporal parameters, many researchers (Combes et al, 2018;Whittaker et al, 2019) have used the mean power frequency (MPF) and median frequency (MDF) of sEMG signals to analyze muscle fatigue. Spectral parameters such as MPF and MDF tend to decrease with the advent of muscle fatigue, and their rates of decrease are termed rate of fatigue (ROF) (Gerdle and Fugl-Meyer, 1992;Cifrek et al, 2009;Yung et al, 2012;Cruz-Montecinos et al, 2018), which is frequently used to analyze the fatiguing effects of exercise on muscles.…”

RESPOSTA CRÔNICA DA CARGA INTERNA DE TREINAMENTO: treinamento continuo versus treinamento intermitente

“…Os autores apontaram em seu estudo que o VO2max é considerado um dos mais importantes preditores de mortalidade por DCV; além do tabagismo, hipertensão (hipertensão) e distúrbios do colesterol, os baixos níveis de CRF aumentam o risco de DCV, estão associados à morbidade e mortalidade pela mesma causa, bem como à mortalidade por todas as causas, onde é possível apontar também que evidências epidemiológicas mostram a ligação entre o VO2max e sua associação com condições crônicas que desencadeiam DCV e, subsequentemente, aumentam a probabilidade de morte. Combes et al (2018) concluíram que dois exercícios intermitentes e contínuos de intensidade de exercício e gasto energético combinados apresentaram respostas fisiológicas diferentes, sendo que o treino intermitente parece levar a um maior recrutamento de fibras de contração rápida, que possuem menos equipamento mitocondrial e são mais sujeitas a adaptações oxidativa. Tais resultados podem ser justificados pois o treino intermitente está associado a um padrão constante de recrutamento de unidades motoras com maior recrutamento de fibras musculares do tipo II.…”

Effects of molecular hydrogen supplementation on fatigue and aerobic capacity in healthy adults: A systematic review and meta-analysis

“…Third, subgroup analyzes revealed that H 2 supplementation may be more effective for fatigue induced by intermittent exercise as compared to continuous exercise ( 24 , 28 , 30 ). This may be because bouts of intermittent exercise are typically completed against greater external physical load, which may enable mitochondrial respiratory function to more efficiently intake H 2 and/or increase the concentration level of ROS in muscles, boosting the redox procedure between ROS and molecular hydrogen ( 58 – 60 ).…”