Can Brain Stimulation Increase Endurance? Or is there still no easy way to get into shape?

Exploring the limits of human endurance has inspired innovative research into brain stimulation techniques.

Transcranial direct current stimulation, or tDCS, is a non-invasive method where low-intensity electrical currents are applied to the scalp to influence brain activity. It has shown promise in enhancing exercise performance in strength and cycling studies, but its effects on running endurance remain unclear.

In a recent trial, researchers investigated whether tDCS applied to the motor cortex could improve running endurance by measuring the time runners could sustain high-intensity treadmill exercise.

How tDCS could energize performance - the hypothesis
Our nerve cells communicate with each other by electrical impulses. TDCS works by altering the excitability (the threshold for when to send an impulse) of nerve cells in targeted areas of the brain. Anodal stimulation increases activity, while cathodal stimulation decreases it.

Theoretically, applying tDCS over the motor cortex could enhance endurance by boosting the brain’s drive on the muscles, reducing perceived fatigue, and delaying exhaustion.

Still, evidence for this remains mixed. While some studies on cycling and strength exercises suggest potential benefits, others show no clear improvement.

The current trial took a step forward by using a larger sample and controlling for placebo effects.

The study
The study examined the effect of tDSC in 45 trained male athletes. Researchers monitored oxygen consumption, heart rate, and blood lactate to track physiological responses and subjective ratings of perceived exertion.

Endurance performance was assessed using a “time to exhaustion” test, a standard method where participants run at a constant high intensity until they can no longer continue.

Despite a rigorous design, the study found no significant differences between active stimulation and a placebo condition in running performance or physiological markers like heart rate, oxygen consumption, and blood lactate.

Interestingly, the athletes’ baseline fitness levels, measured by maximal oxygen consumption, also did not predict their response to tDCS. While some prior studies hinted that less-trained individuals might benefit more, this trial did not support that idea for runners.

These findings suggest that tDCS does not boost running endurance.

Is there a road ahead for tDCS and endurance?
Although this study concluded that a single session of tDCS does not enhance running endurance, it raises intriguing questions for future research.

Could multiple sessions, higher intensities, or different stimulation protocols produce better results? Might individual differences, such as brain structure or genetic factors, influence responsiveness to tDCS?

For now, tDCS appears unlikely to revolutionize endurance sports or pose a doping concern. So, unfortunately, it seems there’s still no easy way to get in shape — unless wishful thinking suddenly becomes a full-body workout.

About the scientific paper:

First author: Geraldine Martens, Belgium and Canada
Published in: PLoS ONE, December 2024
Link to paper: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0312084