Could a single workout session help slow down the growth of cancer cells? That question, which might have sounded far-fetched just a few years ago, is now at the center of a remarkable new study that’s giving hope to breast cancer survivors and adding fresh urgency to the role of exercise in cancer care.
On September 12, 2025, researchers led by Francesco Bettariga at Edith Cowan University in Australia unveiled findings that both resistance training and high-intensity interval training (HIIT) can trigger a short-term surge in certain proteins—known as myokines—in the blood of breast cancer survivors. According to the team, these myokines, specifically decorin, IL-6, and SPARC, are released by skeletal muscles when we exercise. While they’re already known to help with muscle growth, fat burning, and reducing inflammation, the new study shows they may also have the power to slow the growth of cancer cells themselves.
"The results from the study show that both types of exercise really work to produce these anti-cancer myokines in breast cancer survivors," said Bettariga in a statement, as reported by multiple outlets. "The results from this study are excellent motivators to add exercise as standard care in the treatment of cancer."
The study, which was published last month and involved 32 women who had survived breast cancer, set out to answer a very specific question: Can a single bout of physical activity create measurable, beneficial changes in the blood that might slow the progression of cancer? To get their answer, researchers took blood samples from participants before exercise, immediately after, and then again 30 minutes later. They were looking for changes in the levels of myokines, those remarkable proteins that muscles pump out when they’re put to work.
The results were striking. After just one session of either interval training or weightlifting, participants’ blood showed a significant increase in decorin, IL-6, and SPARC. But what happened next was even more compelling. When the researchers exposed laboratory-grown breast cancer cells to the post-exercise blood samples, they found that the cancer cells’ growth slowed down. This was true even for triple-negative breast cancer cells—a form of the disease that lacks hormone receptors and was previously thought to be less responsive to exercise-related interventions.
According to the New York Times, which covered the study’s release, the molecules released by exercising muscles helped suppress the growth of breast cancer cells in the lab. For survivors and their families, this is more than just an academic breakthrough—it’s a potential game-changer in how we think about recovery and long-term health after cancer.
Preclinical and experimental studies have long hinted that myokines can slow tumor growth, including in breast cancer. But until now, it wasn’t clear whether the same phenomenon would occur in people who had already survived cancer. The latest research bridges that gap, providing real-world evidence that even a single workout can trigger biological changes that might help keep cancer at bay.
"Our findings demonstrate that both resistance training and high-intensity interval training elicit acute changes in circulating myokines and reduced cancer cell growth, which may contribute to proposed biological pathways involved in cancer control. However, further research is needed to determine the long-term relevance of these responses for disease recurrence in breast cancer survivors," the authors wrote in their summary.
This isn’t to say that exercise is a cure or a replacement for conventional treatments like chemotherapy or radiation. But it does suggest that exercise could be a valuable addition to the standard toolkit for cancer care. Bettariga and his team are careful to note that more research is needed to determine whether these short-term effects translate into long-term benefits—such as reducing the risk of cancer recurrence or improving overall survival rates.
The study’s design was straightforward but powerful. Thirty-two women who had survived breast cancer were recruited for the experiment. Each participant completed a session of either resistance training or HIIT. Blood samples were drawn at three key points: before exercise, immediately after, and 30 minutes post-exercise. The samples were then analyzed for myokine levels and tested on laboratory-grown breast cancer cells to observe any changes in growth rates.
What’s particularly intriguing is the effect on triple-negative breast cancer cells. These cells lack the hormone receptors that many traditional treatments target, making them notoriously difficult to treat. Yet, in this study, even these stubborn cells appeared to be slowed down by the surge of myokines released after exercise. It’s a finding that could have wide-reaching implications for future research and treatment strategies.
So, how do these myokines work their magic? When muscles contract during exercise, they release myokines into the bloodstream. These proteins have a range of beneficial effects: they help regulate metabolism, reduce inflammation, and support tissue repair. In the context of cancer, they appear to interfere with the signaling pathways that allow tumors to grow unchecked. Think of them as the body’s own internal defense system—one that can be activated simply by getting up and moving.
Of course, the study’s authors are quick to caution that their findings are just the beginning. "Further research is needed to determine the long-term relevance of these responses for disease recurrence in breast cancer survivors," they emphasized. In other words, while a single workout can spark measurable changes, scientists still need to find out whether regular, ongoing exercise can have a lasting impact on cancer outcomes.
For now, though, the message is clear: exercise isn’t just good for the heart, the waistline, or mental health—it may also play a role in keeping cancer at bay. As Bettariga put it, "The results from this study are excellent motivators to add exercise as standard care in the treatment of cancer."
What does this mean for breast cancer survivors? While it’s too early to make sweeping clinical recommendations, many oncologists and exercise specialists are already encouraging patients to incorporate physical activity into their recovery plans. The benefits are manifold, from improved strength and mobility to better mood and reduced fatigue. Now, with this new evidence, there’s even more reason to lace up those sneakers or hit the gym.
It’s worth noting that the study focused on two distinct types of exercise: resistance training (think weightlifting) and high-intensity interval training. Both were effective in boosting myokine levels and slowing cancer cell growth. This suggests that survivors have options when it comes to choosing activities that fit their preferences and abilities.
As the research community continues to explore the links between exercise and cancer, one thing is becoming increasingly clear: the body has powerful tools for healing itself, and sometimes, all it takes to activate them is a single workout. For those living with or recovering from cancer, that’s a message worth taking to heart.