# Plasma longitudinal metabolic changes with acute maximal aerobic exercise and one-hour recovery

## TL;DR

This study shows how people with different fitness levels have distinct metabolic responses during and after intense aerobic exercise.

## Contribution

The study reveals novel metabolic differences in bile acid and purine metabolism between high and low fitness individuals during maximal exercise and recovery.

## Key findings

- High fitness individuals showed rapid clearance of bile acids and amino acids during exercise onset.
- Low fitness individuals had reduced clearance of triacylglycerols and glycerophospholipids during recovery.
- Metabolic differences were identified using likelihood-ratio testing and hierarchical clustering of metabolomic data.

## Abstract

Total body metabolism continuously adapts to match energy supply with demand. During exercise metabolic alterations occur because skeletal muscles require a continuous supply of newly generated ATP to match the demand of the intensity of the exercise, and products of muscle metabolism must be eliminated. The metabolic and energetic flexibility greatly impact maximum physical fitness and exercise duration, as well as the speed of elimination of metabolism end-products. However, so far, the temporal profiling of metabolomic changes in response to exercise of persons with different fitness levels remains relatively unexplored. This study examined metabolic changes during each person’s peak aerobic exercise and one-hour post-exercise recovery in 29 Baltimore Longitudinal Study of Aging (BLSA) participants.

Blood samples were collected at baseline, and at 3-min intervals during both incremental exercise on a treadmill until exhaustion and during recovery. Participants were classified based on the stage when they reached exhaustion as low fitness (LF, completing up to 3 treadmill incremental stages) or high fitness (HF, completing up to 7 incremental stages). The time course of exercise-associated changes in the circulating metabolome were mapped and unique metabolomic trajectories were identified with likelihood-ratio testing and hierarchical clustering.

The HF group had rapid clearance of bile and amino acids at exercise onset, along with effective clearance of triacylglycerols and glycerophospholipids during recovery. In contrast, the LF group had much reduced clearance of these metabolites and had persistent elevation of triacylglycerols and glycerophospholipids.

These findings highlight differences in bile acid clearance and purine metabolism in people of differing fitness levels and provide novel insights into the role of metabolic adaptive responses to aerobic exercise assessed through circulating metabolomic measures.