Metabolic Flexibility Following High-Intensity Interval Exercise in Active Females: Effect of Feeding State

Year 2025, Volume: 16 Issue: 2, 387 - 397, 30.08.2025

Maryam Ebrahimi

https://doi.org/10.54141/psbd.1678172

Abstract

Metabolic flexibility is tightly regulated during exercise through the action of metabolites and metabolic enzymes. This randomized parallel-group study aimed to investigate how fed vs fasted state high-intensity interval exercise (HIIE) changes Glucose, lactate, pyruvate dehydrogenase kinase-4 (PDK-4), and carnitine palmitoyltransferase-1 (CPT-1) levels. 23 active females (20.09 ± 1.04 years of age) were selected from eligible volunteers and were randomly assigned into fed and 14-h fast groups. In each group, 6 participants randomly performed 1:4 HIIE (1 min all-out run, 4 min walk, for 20 minutes), and the other participants were seated. After a 5-minute cooldown, blood samples were collected from the brachial vein. Higher lactate levels were similar after HIIE in both feeding states. Fed-HIIE participants showed lower glucose levels, and fast-HIIE participants showed lower PDK-4 and CPT-1 levels than their control counterparts. It seems in the fasted 1:4 HIIE, glucose oxidation is the dominant energy production pathway. Lactate produced during exercise may be used as the precursor of gluconeogenesis in fasting.

Keywords

CPT-1 , Glucose , HIIE , Lactate , PDK-4

Ethical Statement

Ethical approval for this trial was received from the Iran National Committee for Ethics in Biomedical Research (IR.GUMS.REC.1398.002) and is registered in the Iran Registry of Clinical Trials (IRCT20190213042702N1). All participants were fully informed about the research procedure and signed an informed consent form.

Supporting Institution

University of Guilan

Project Number

15p204464

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