Exercise Intensity and Circulating Exerkine Responses: A Narrative Review of Selected Molecules

Area of Science:

• Exercise physiology
• Molecular biology
• Endocrinology

Background:

• Exerkines are bioactive molecules released during physical exercise, mediating systemic adaptations.
• Previous research focused on exercise modalities, leaving the impact of exercise intensity on exerkine responses unclear.

Purpose of the Study:

• To review the effects of different exercise intensities on nine key circulating exerkines in healthy populations.
• To synthesize current evidence on intensity-dependent exerkine regulation.

Main Methods:

• Narrative review of studies examining exercise intensity and exerkine levels.
• Focused on irisin, follistatin-like 1, myostatin, FGF21, follistatin, leptin, adiponectin, apelin, and BDNF.
• Included studies with sufficient data in healthy individuals.

Main Results:

• Acute exercise alters several exerkines; some studies report greater responses at higher intensities.
• Findings across intensities show increases, decreases, or no significant changes in exerkines.
• Chronic exercise interventions yield inconsistent results regarding exerkine level changes.

Conclusions:

• Exercise intensity may influence exerkine responses, particularly in acute settings.
• Current evidence is limited and inconsistent, suggesting a need for further research.
• Findings are descriptive and hypothesis-generating due to the review's narrative design.