Predicting perceived exertion during high-intensity exercise using quantitative MRI: insights from T2* value and...

Area of Science:

• Exercise Physiology
• Biomedical Imaging
• Sports Science

Background:

• Subjective exercise intensity, measured by Rating of Perceived Exertion (RPE), is crucial for training.
• Objective biomarkers are needed to complement RPE.
• Magnetic Resonance Imaging (MRI) offers potential for non-invasive muscle assessment.

Purpose of the Study:

• To investigate the relationship between MRI-derived skeletal muscle biomarkers and RPE.
• To identify which MRI biomarker best predicts RPE.
• To explore the potential of MRI T2* value as a non-invasive RPE biomarker.

Main Methods:

• Participants underwent MRI scans before and after exercise.
• T2* relaxation time and Cross-Sectional Area (CSA) of skeletal muscle were measured.
• Correlation and random forest analyses were used to assess relationships with RPE.

Main Results:

• T2* value and CSA showed time-dependent changes post-exercise.
• The percent change in T2* (T2* PC-post/pre) was significantly correlated with RPE (ρ=0.45, p<0.01).
• Random forest analysis identified T2* PC-post/pre as the strongest predictor of RPE.

Conclusions:

• Post-exercise T2* value changes reflect metabolic stress and are a specific predictor of RPE.
• T2* value is a more sensitive biomarker for RPE than CSA or muscle strength.
• MRI-derived T2* value shows promise as a non-invasive biomarker for assessing subjective exercise intensity.