Scientists have made a breakthrough in studying the link between exercise and the absence of anxiety and depression. Image source: sciencealert.com
We’ve all heard that exercise is good for health. Indeed, regular workouts strengthen the heart, improve metabolism, and help keep the body in shape. But new research shows it’s not just about muscles — physical activity directly affects brain biochemistry, specifically through a molecule that few people have heard of.
How Exercise Helps with Anxiety and Depression
Many of us live with some form of mental health issues: anxiety, depression, or other disorders. People report mental illnesses almost three times less frequently than physical ones, and access to diagnosis and treatment can take years. Medications for mood disorders sometimes cause side effects that lead patients to abandon treatment. Traditional psychotherapy is expensive and far from always covered by insurance.
But there is a tool that doctors have long prescribed to improve heart health and metabolism, and it turns out to be an incredibly useful addition to mental health care. That tool is physical exercise. Science confirms: workouts truly reduce symptoms of anxiety and depression in both the short and long term. They help with mood regulation and, most importantly, increase emotional resilience to acute stress.
You’ve probably heard the expression “runner’s high.” This feeling of euphoria after a workout is largely explained by a surge of endocannabinoids and endorphins — hormones and molecules that literally make us happy. But it turns out that they’re not the only ones responsible for the good mood after the gym.
What Is Tryptophan
The main character of this story is tryptophan. It’s an essential amino acid that we obtain from food, and it plays many important roles in the body. Serotonin — that very “happiness hormone” — is produced from tryptophan. But tryptophan can also be broken down through another pathway, producing molecules with entirely different effects on the brain and body.
The main pathway of tryptophan breakdown is called the kynurenine pathway. And this is where things get really interesting. Some products of this pathway, such as kynurenic acid, protect against inflammation and are beneficial for brain health. Others, such as quinolinic acid, are conversely associated with toxicity and inflammatory processes.
The fact is that many chronic conditions like depression, Alzheimer’s disease, and even cancer are associated with elevated levels of specifically the “bad” kynurenine metabolites. Simply put, depending on which route tryptophan breakdown takes, we either get brain protection or, conversely, harm. And this is exactly where physical exercise enters the picture, as it appears capable of switching this route in the right direction.
Many types of physical activity can increase the amount of tryptophan metabolites and improve mood. Image source: sciencealert.com
How Exercise Affects the Brain
Research has shown that physical exercise causes an immediate and direct increase in brain-protective molecules such as kynurenic acid. Its elevated levels were detected in the blood and muscles immediately after a workout. Moreover, this works not only for runners — beneficial changes have been found after cycling, strength training, and high-intensity interval workouts.
But that’s not all. People with additional metabolic problems, such as type 2 diabetes, also demonstrate positive shifts in tryptophan metabolites even after a single workout. And what’s especially encouraging — improvements have been recorded across different age groups. This means that both young and elderly people benefit.
To date, laboratory studies have mainly used classic protocols — cycle ergometers, strength exercises. However, scientists emphasize that higher physical activity in general improves the profile of these metabolites. In other words, you don’t necessarily have to exercise strictly in a lab or follow a rigid program to get the effect. That said, research in this area continues: scientists still need to precisely understand the molecular mechanisms explaining why exercise so effectively regulates these metabolites.
Why Everyone Should Exercise
Ultimately, physical exercise is a powerful tool for improving mental health. There is compelling evidence that workouts help manage stress and stimulate the production of “happiness hormones” and protective metabolites that provide support for mood disorders.
But it’s not limited to biochemistry. A workout is also a change of scenery, social interaction, or simply a conscious shift of attention for a certain period of time. All of these factors are important for mental health. Group activities, running clubs, team sports — can work as universal mood boosters through multiple channels simultaneously.
The study’s author, Megan McCue, a postdoctoral fellow in the Faculty of Health Sciences at McMaster University, notes that even when a workout seems like the last thing you want to do, the result is absolutely worth the effort.
