Exercise elicits a wide range of physiological changes in the body that improve multiple aspects of cardiovascular, neurological, and metabolic health. The molecular mechanisms that drive these improvements are not well understood. Findings from a new study suggest that an acute bout of aerobic exercise alters more than 9,000 distinct molecules in the human body to positively influence health.

The study involved 36 adults between the ages of 40 and 75 years. The average body mass index among the participants was 28, which is considered overweight. Their steady-state blood glucose levels ranged from 86 to 220 milligrams per deciliter, suggesting a wide range of insulin resistance, from very low to very high.

The authors of the study collected blood samples from all the participants before exercise and two, 15, 30, and 60 minutes afterward. They collected fasting blood samples from 15 of the participants the morning after the exercise protocol to assess inter-day variability. One group of participants engaged in an acute bout of aerobic exercise on a treadmill for eight to 12 minutes at their maximum capacity. A control group of 14 participants did not perform any exercise.

Analysis of the participants' blood before and after exercise revealed that an acute bout of aerobic exercise induced extensive changes in 9,815 molecules, including proteins, lipids, genes, immune markers, and many others, that correlate with a person’s aerobic fitness.

The authors of the study suggested that their findings could lay the groundwork for the development of a simple blood test that measures fitness in the future.

• Link to full study.