Serotonin: Good For Mood, Bad For Endurance by Joan Kent, PhD
Serotonin: Good For Mood, Bad For Endurance
By Joan Kent, PhD
Serotonin is a brain chemical with different functions.
• It’s a neurotransmitter that’s targeted and enhanced by several antidepressants.
• It’s the precursor of melatonin, the “sleep hormone” and anti-inflammatory.
• It affects satiety and modulates general food intake and carbs specifically.
• It’s a vasoconstrictor.
• At high levels, it can make us lethargic.
• It plays a role in energy expenditure and motor activity.
Exercise can raise levels of serotonin. People typically consider that beneficial because serotonin is often referred to – somewhat mistakenly – as a “happiness” hormone.
But among athletes, increased serotonin is known to affect endurance training negatively by bringing on fatigue. Various studies over the past decade or so have shown this to be true in both human and animal studies.
The connection between serotonin and fatigue during endurance exercise is more pronounced in high-intensity (“exhaustive”) training. We definitely want to keep working out, so how can we prevent unnecessary fatigue?
Red Ginseng
Red (panax) ginseng has been promoted as an ergogenic aid for endurance athletes. Having never tried it, I can’t vouch for its effectiveness.
Tests on animals, however, suggest that the mechanism behind the ergogenic benefit of ginseng lies in its ability to suppress brain levels of serotonin.
The side effects of red ginseng vary and may include anxiety, headache, insomnia, nervousness, or dizziness. If consumed with coffee, it can cause irregular heart rhythms. Anyone taking meds for hypertension should avoid red ginseng.
Peony Root
Other animal studies show that peony root (paeonia radix) works similarly. It reduces fatigue by blocking the synthesis of serotonin during exercise.
The drawbacks of peony root are stomach upset, rashes in sensitive people, or its ability to slow blood clotting. That may lead to negative interactions with anticoagulant meds – either prescription drugs like Coumadin or over-the-counter items, such as aspirin, ibuprofen, or naproxen (Naprosyn).
Acupuncture and glucose
Still other animal studies have shown that acupuncture at selected sites or glucose injections in the brain can improve treadmill running by suppressing serotonin synthesis and release.
So the serotonin/fatigue connection in athletes and animals has been shown time and again.
Protein To the Rescue
When I long ago learned of the connection between exercise-induced serotonin and fatigue, my first thought was of protein. A combination of mid-ride protein and starch would tend to block serotonin synthesis, I figured.
Sure enough, research supports that.
Protein added to a carb supplement has been shown, for example, to enhance running endurance capacity in football players toward the end of a game.
Experiments on rats trained on a treadmill and given free access to food and a choice between water and a water/amino acid solution showed that the rats preferred the amino acid solution when made to run on the treadmill. Tests revealed decreased brain serotonin in those rats. This suggests an ergogenic benefit of the amino solution.
How Can You Use This Info?
Fatigue has multiple symptoms that may occur simultaneously when you work out. For best results overall, a few basic guidelines should help.
Stay hydrated, of course, always. Dehydration produces severe fatigue (and worse).
Don’t overdress. Hyperthermia can increase perceived effort and derail endurance efforts.
Add protein to your fuel mix. Preferable types would be fairly easy to digest, such as organic pea protein powder. It could easily be added to the recipe for Dr. Joan’s Potato Goo or the No-Bonk Breakfast, both in my book The Sugar-Free Workout.
Wishing you excellent results with your endurance workouts in the year ahead!