How intense is high-intensity interval training? Biomarker responses and associations with training load and fitness.

ABSTRACT: High-intensity interval training (HIIT) enhances physical performance but requires close monitoring to avoid illnesses/injuries. We monitored physiological responses at rest during and up to 14 days following a 7-day HIIT intervention to identify chronic physiological changes and to explore correlations between blood biomarkers (blood count, cytokines, creatine kinase [CK], urea, ferritin, and transferrin), training load, cardiorespiratory fitness (VO_2max), and muscle soreness. Thirty participants were randomly allocated to either HIIT shock cycle (10× HIIT in 7 days) (1) with or (2) without additional low-intensity training after each HIIT session or (3) control group. Repeated HIIT resulted in a chronic decrease of hemoglobin, hematocrit, red blood cells, CK, interleukin [IL]-

SUBMITTER: Haller N 

PROVIDER: S-EPMC12595005 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature