Different whole body HIIT protocols do not promote different muscle thickness and functional adaptations among healthy physically active subjects

• Published in: Frontiers in sports and active living Vol. 6; p. 1513030
• Main Authors: Evangelista, Alexandre L., de Camargo, Júlio B. B., Rica, Roberta L., Carnevali Júnior, Luiz Carlos, Mallett, Gregg S., Bullo, Valentina, Bergamin, Marco, Gobbo, Stefano, Bocalini, Danilo S.
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 15.01.2025
• Subjects: cardiorespiratory fitness; exercise protocols; high-intensity interval training; muscle fitness; muscle thickness; Sports and Active Living; high-intensity interval training; muscle thickness; cardiorespiratory fitness; exercise protocols; muscle fitness
• ISSN: 2624-9367; 2624-9367
• DOI: 10.3389/fspor.2024.1513030

Despite robust evidence on the benefits of high intensity interval training using body weight (WB-HIIT), the effects of different training configurations on morpho-functional adaptations are still unclear. Therefore, the aim of the present study was to assess the effects of two distinct WB-HIIT protocols on morphological and general fitness adaptations in healthy active young individuals. Thirty-four participants (22 males and 12 females) were randomly assigned to one of the following groups: 30 s of all-out effort interspersed with 10 s of passive recovery (G30 × 10,  = 17) or 40 s of an all-out effort interspersed with 20 s of passive recovery (G40 × 20,  = 17). Nine exercises were performed for both protocols, in two weekly sessions, during a 6-week intervention period. Morphological (ultrasound-derived muscle thickness of the vastus lateralis [MTVL]) and general fitness (muscle endurance and maximal oxygen consumption) assessments were performed at pre- and post-intervention moments. Both training protocols elicited significant improvements in all dependent variables (  < 0.05), with no significant between-group differences. Regardless of the training configuration, both WB-HIIT programs serve as time-efficient strategies to induce changes in muscle thickness of the vastus lateralis and functional adaptations in healthy, physically active young individuals.