Exercise-Induced Muscle Damage after a High-Intensity Interval Exercise Session: Systematic Review.

High-intensity interval training (HIIT) is considered an effective method to improve fitness and health indicators, but its high-intensity exercises and the mechanical and metabolic stress generated during the session can lead to the occurrence of exercise-induced muscle damage. Therefore, this study aimed to describe, by means of a systematic review, the effects of a single HIIT session on exercise-induced muscle damage. A total of 43 studies were found in the Medline/PubMed Science Direct/Embase/Scielo/CINAHL/LILACS databases; however, after applying the exclusion criteria, only 15 articles were considered eligible for this review. The total sample was 315 participants. Among them, 77.2% were men, 13.3% were women and 9.5 uninformed. Their age ranged from 20.1 ± 2 to 47.8 ± 7.5 years. HIIT protocols included running with ergometers (n = 6), CrossFit-specific exercises (n = 2), running without ergometers (n = 3), swimming (n = 1), the Wingate test on stationary bicycles (n = 2), and cycling (n = 1). The most applied intensity controls were %vVO2max, "all out", MV, MAV, Vmax, and HRreserve%. The most used markers to evaluate muscle damage were creatine kinase, myoglobin, and lactate dehydrogenase. The time for muscle damage assessment ranged from immediately post exercise to seven days. HIIT protocols were able to promote changes in markers of exercise-induced muscle damage, evidenced by increases in CK, Mb, LDH, AST, ALT, pain, and muscle circumference observed mainly immediately and 24 h after the HIIT session.

Effect of a short-term whole-body high-intensity interval training on fitness, morphological, and functional parameters in untrained individuals.

BACKGROUND: High-intensity interval training protocols using the body weight (WB-HIIT) as resistance could be an interesting and inexpensive alternative due to the absence of equipment required (low cost) and the possibility to be performed in a wide range of locations. Therefore, the purpose of the present study was to analyze the effects of a short-term WB-HIIT protocol on muscle thickness (MT), muscular endurance (ME), one maximum repetition test (1RM), and maximum oxygen uptake (VO2max) of untrained individuals. METHODS: Fifty healthy men (28.2±6.7 years, 77.5±26.2 kg, 171±10 cm, 23.2±8.2% Fat) were randomized into WB-HIIT (N.=25) or control (CON, N.=25) group. The WB-HIIT performed 9 exercises (40-second stimulus in all out intensity/ 20-second of passive recovery) divided into 3 blocks with 2 sets each for 6 weeks (three times a week). RESULTS: Only WB-HIIT resulted in a significant increase in MT, ME, 1RM, and VO2max (all P<0.05) outcomes and were significantly greater compared to CON (all P<0.05). CONCLUSIONS: Our results demonstrate that a WB-HIIT program can be a time-efficient strategy to promote changes on fitness, morphological and functional parameters in previously untrained sedentary individuals.

The dose-response phenomenon associated with strength training is independent of the volume of sets and repetitions per session / O fenômeno de dose-resposta associado ao treinamento de força é independente do volume de séries e repetições por sessão / El fenómeno de dosis-respuesta asociado al entrenamiento de fuerza es independiente del volumen de series y repeticiones por sesión

ABSTRACT Introduction There are few studies on the effectiveness of training models with high volume sets per session in particular muscle groups. Objective The aim of the study was to investigate the effects of different resistance training (RT) repetitions with equalized volumes on muscle adaptations. Methods This study used an experimental design in which forty-seven volunteers underwent 8 weeks of RT after having been distributed randomly into three groups: ten sets of three maximum repetitions (10x3), three sets of ten maximum repetitions (3x10) and five sets of six maximum repetitions (5x6) for each muscular group per training session. Maximum strength (1RM test) and muscle thickness (MT) were evaluated as outcomes. Results A significant main effect (p=0.001) of time on maximum strength was observed for the three groups, but no significance was observed (p>0.05) in time x group interactions. A significant main effect (p=0.001) of time was observed on MT for biceps, triceps and vastus lateralis, without significant differences for time x group interactions. Significant correlations were found between maximum strength and muscle thickness after general statistical analyses for all protocols. Conclusion Improvements in maximum strength and muscle thickness are similar when repetition volumes are equalized through the number of series and repetitions. Level of evidence I; Therapeutic studies, investigation of treatment results.

RESUMO Introdução Existem poucos estudos sobre a eficácia de modelos de treinamento com conjuntos de alto volume por sessão em grupos musculares específicos. Objetivos O objetivo do estudo foi investigar os efeitos de diferentes repetições do treinamento de resistência (TR) com volumes equalizados nas adaptações musculares. Métodos Este estudo tem desenho experimental com 47 voluntários que realizaram oito semanas de TR depois de serem distribuídos randomicamente em três grupos: dez séries de três repetições máximas (10x3), três séries de dez repetições máximas (3x10) e cinco séries de seis repetições máximas (5x6) para cada grupo muscular por sessão de treinamento. A força máxima (teste de 1RM) e a espessura muscular (EM) foram avaliadas como desfecho. Resultados Verificou-se efeito significativo (p = 0,001) sobre o tempo na força máxima nos três grupos, contudo, nenhuma significância (p > 0,05) foi observada nas interações entre tempo e grupo. Constatou-se efeito significativo (p = 0,001) do tempo sobre a EM para bíceps, tríceps e vasto lateral, sem diferenças significativas nas interações entre tempo e grupo. Correlações significativas foram encontradas entre força máxima e espessura muscular depois das análises estatísticas gerais para todos os protocolos. Conclusões A melhora da força máxima e da espessura muscular é semelhante quando o volume de repetições é equalizado considerando o número de séries e repetições. Nível de evidência I; Estudos terapêuticos, investigação dos resultados do tratamento.

RESUMEN Introducción Existen pocos estudios sobre la eficacia de modelos entrenamiento con conjuntos de alto volumen por sesión en grupos musculares específicos. Objetivos El objetivo del estudio fue investigar los efectos de diferentes repeticiones del entrenamiento de resistencia (ER) con volúmenes ecualizados en las adaptaciones musculares. Métodos Este estudio tiene diseño experimental con 47 voluntarios que realizaron ocho semanas de ER después de ser distribuidos aleatoriamente en tres grupos: diez series de tres repeticiones máximas (10x3), tres series de diez repeticiones máximas (3x10) y cinco series de seis repeticiones máximas (5x6) para cada grupo muscular por sesión de entrenamiento. La fuerza máxima (test de 1RM) y el espesor muscular (EM) fueron evaluados como conclusión. Resultados Se verificó efecto significativo (p = 0,001) sobre el tiempo en la fuerza máxima en los tres grupos, sin embargo, ninguna significancia (p> 0,05) fue observada en las interacciones entre tiempo y grupo. Se constató efecto significativo (p = 0,001) del tiempo sobre el EM para bíceps, tríceps y vasto lateral, sin diferencias significativas en las interacciones entre tiempo y grupo. Fueron encontradas correlaciones significativas entre fuerza máxima y espesor muscular después de los análisis estadísticos generales para todos los protocolos. Conclusiones La mejora de la fuerza máxima y del espesor muscular es semejante cuando el volumen de repeticiones es ecualizado considerando el número de series y repeticiones. Nivel de evidencia I; Estudios terapéuticos, investigación de los resultados del tratamiento.