Efectos del entrenamiento intervalado de alta intensidad sobre parámetros fisiólogicos, neuromusculares y perceptivos del rendimientooptimización de la carga de entrenamiento basada en el intervalo de trabajo y la especificidad deportiva

Résumé

High- Intensity Interval Training (HIIT) has shown to be an effective method to improve endurance. It has been demonstrated that HIIT generates higher increases in maximal and submaximal performance parameters than continuous methods of low or moderate intensity. This fact is based on the different effects observed on the exercise responses, due to the partition of the training load. However, a precise modulation of the load components is necessary to optimize HIIT sessions and increase its effectivity. The present doctoral thesis deepens upon the methodological aspects of these formats, and the influence on the parameters used to monitor exercise responses. Specifically, it analyzes the effects of work-interval duration on heart rate, blood lactate concentration, rate of perceived exertion, and neuromuscular status, in relationship with the sport disciplines. To develop this thesis, we have completed a literature review on the topic, and identified several aspects that had not been sufficiently clarified. The first issue that presented some controversies was the categorization of a HIIT protocol as short or long, based on the work-interval duration. This aspect was addressed in the study 1, in which we compared the metabolic, cardiac, and perceptual responses, among four HIIT sessions of equal load but different work-interval duration (10 s, 50 s, 90 s, and 130 s). The findings of this study allowed us to define the interval formats based on the responses observed in each session. The second point that showed no consensus in the literature was related to the criteria to determine the total volume recommended for HIIT sessions. In this line, in the studies 1 and 3, we have established an individualized parameter based on the time to exhaustion reached in a previous test. The third aspect identified was scant evidence associated to the neuromuscular responses during HIIT sessions. In particular, no studies had compared the neuromuscular status among regular HIIT sessions not conducted until exhaustion, and the specific effects on countermovement jump (CMJ) sub-phases. To address this point, we initially completed a study (study 2) to assess the reliability of measures of the CMJ performance variables, during a four-sessions repeated measures trials, and analyzed across the different sub-phases of the execution. This allowed us to establish the measures of higher reliability that would be used as parameters for the detection of neuromuscular fatigue during the completion of different HIIT sessions (study 3). The last aspect found was the lack of studies aimed to analyze the possible differences in the parameters to monitor HIIT associated to the specificity of the sport disciplines. For this purpose, in the statistical analyses of the studies 1 and 3 we have included the type of the sport discipline as inter-subject factor. In this way, we could contrast if an interaction between this factor and the type of protocols was observed. The results of the present compendium indicate that HIIT sessions with short work-interval duration entail efforts lower than one minute, while HIIT sessions with long work-interval duration above 90 seconds. They also indicate that the relative accumulated volume may be used as a valid criterion to design HIIT sessions. Furthermore, they allow establish the reliability of measures of the CMJ performance variables for the different sub-phases, and determine that the neuromuscular status is conditioned by the relative total volume accumulated, but not by the type of work-interval duration implemented. Finally, the present findings suggest that the acute responses observed during HIIT sessions with different work-interval duration, are independent to the functional profile of the sport discipline. Based on the mention results we can state the present conclusions: • The work-interval duration determines the metabolic and perceptual responses during HIIT sessions. • HIIT with short work-interval duration (< 60 s) generate low blood lactate concentrations (≈ 3 mmol · L-1), and a moderate rate of perceived exertion. • HIIT with long work-interval duration produce high blood lactate concentrations (≈ 7 mmol · L-1) and a strong rate of perceived exertion, indicating a major participation of the glucolitic pathway for the energy generation. • The performance observed in a time to exhaustion test may be used as a valid criterion to determine the total volume of a HIIT session. • The neuromuscular fatigue associated to the completion of a given HIIT session may be detected through the analysis of the sub-phases of the CMJ test. • During HIIT sessions, the neuromuscular status in not affected by the type of work-interval duration selected. • The total relative volume of a HIIT session diminishes the neuromuscular performance when is equivalent to three time the distance reached in a previous time to exhaustion test. • The sport specificity and the characteristics of the physical demands of the studied disciplines do not condition the metabolic, perceptual, and neuromuscular responses expected during HIIT sessions with different work-interval duration, and volumes.