We know that lifestyle choices significantly impact our health, and cancer is no exception. Factors like smoking and obesity are well-known risks, but what about physical activity? Strong evidence shows that regular exercise isn't just good for your heart and waistline; it's also linked to a lower risk of developing several types of cancer, including colon, breast, endometrial, stomach, and esophageal cancers. In fact, estimates suggest that physical inactivity might contribute to around 10% of breast and colon cancers.
While moderate activities like jogging or brisk walking are beneficial, a more intense form of exercise is grabbing attention for its potential health impacts: High-Intensity Interval Training, or HIIT. Could these short, sharp bursts of effort offer unique advantages in the fight against cancer?
HIIT isn't about spending hours at the gym. It involves short periods of vigorous exercise (think pushing yourself to 80-90% of your maximum effort) followed by brief recovery periods of rest or low-intensity movement. A typical HIIT session might involve intervals ranging from 30 seconds to 4 minutes of hard work. This contrasts with Moderate-Intensity Continuous Training (MICT), like a steady jog, which keeps your heart rate at a moderate level for a longer, continuous duration. One of HIIT's main appeals is its time efficiency – you can often achieve significant fitness benefits in less time compared to traditional cardio.
Beyond saving time, researchers are exploring whether the intensity of HIIT triggers more powerful biological changes than moderate exercise. Dr. Kerry Courneya, a leading expert in exercise oncology, uses the metaphor of HIIT "stirring the biological soup". The idea is that the higher intensity acts as a stronger stimulus, potentially activating crucial anti-cancer pathways more effectively.
What's in this "soup"? Key ingredients include:
Every time you exercise, especially intensely, your body mobilizes an army of immune cells, pulling them from storage into your bloodstream. This response is largely driven by adrenaline. Importantly, the cells that get the biggest boost from intense exercise include Natural Killer (NK) cells and cytotoxic T-cells – key players in hunting down and destroying abnormal or cancerous cells. Studies show HIIT leads to a greater mobilization of these crucial defenders compared to lower-intensity exercise.
Furthermore, some evidence suggests acute exercise might temporarily decrease the levels of certain immune-suppressing cells (like MDSCs), potentially creating a short-term window where the immune system is more primed to attack cancer. The theory is that these mobilized "killer" cells don't just circulate; they travel into tissues, potentially infiltrating tumors and enhancing immune surveillance throughout the body. Preclinical studies support this, showing exercise increases immune cell infiltration into tumors in mice.
While the acute immune boost from HIIT is compelling, the long-term effects on the resting immune system compared to MICT are more complex and still under investigation, with some studies showing potentially different effects on markers of immune aging (immunosenescence).
Intriguing lab studies add another layer. Researchers have taken blood serum from people after they've exercised (creating "exercise-conditioned serum") and applied it to cancer cells grown in dishes. Several studies found this post-exercise serum can slow the growth of cancer cells (including breast, prostate, and colon cancer lines) and even trigger cancer cell death. One study specifically using serum taken immediately after a HIIT session in colorectal cancer survivors showed it significantly reduced colon cancer cell growth in vitro. This effect was temporary, disappearing when serum taken later was used, suggesting the acute "stirred soup" contains factors that directly challenge cancer cells.
While we don't yet have large-scale human trials proving that doing HIIT prevents people from getting cancer in the first place, the biological case is strong.
Here's what we know:
HIIT offers a time-efficient and biologically powerful way to exercise. Its ability to significantly boost fitness and acutely mobilize cancer-fighting immune cells makes it a very promising strategy, potentially offering enhanced benefits for cancer prevention compared to moderate-intensity exercise alone. While more research is needed to confirm its direct impact on cancer incidence, the existing evidence strongly supports the idea that incorporating high-intensity intervals could be a valuable part of a cancer-preventive lifestyle.
We are strong believers in HIIT at Unleashed Capacity, your Myrtle Beach and Murrells Inlet Personal Training Gym.
As always, consult with your healthcare provider before starting any new exercise program, especially if you have underlying health conditions or are undergoing cancer treatment.