One of the most exciting new studies related to the health benefits of weight training was recently published. Researchers followed 8,677 men, aged 20 to 82, from 1980 to 2003. All of the men were enrolled in the long-term study at the Cooper Aerobics Center in Dallas. Ken Cooper, M.D., who founded the center, is credited with coining the word aerobics and was a fervent advocate of aerobic exercise for more than 30 years. More recently, however, he has also focused on the health benefits of weight training.
The study was led by a team of researchers from the Karolinska Institute in Stockholm, Sweden. The 8,000-plus subjects were monitored over 23 years to determine which of the men developed cancer or died from the disease.
The men who regularly lifted weights and had the highest level of muscular strength—as tested by lifts on bench press and leg press machines—were 30 to 40 percent less likely to die from cancer. The researchers noted that being strong overruled other risk factors associated with cancer, such as age, having lots of abdominal fat and smoking. They suggest lifting weights a minimum of twice a week to protect against cancer.
Why would maintaining strength make a difference? The authors suggest several possible mechanisms. First, lifting weights modulates the activity of several hormones: It helps control insulin metabolism, and excess insulin is linked to several types of cancer. Training increases glucose uptake—independently of insulin—into muscle tissue. Insulinlike growth hormone 1, a.k.a. IGF-1, is an anabolic hormone, but it also fosters the spread of several types of cancer, including breast, colon and prostate cancers. When you lift weights, the liver boosts production of a binding protein that is transported with IGF-1 in the blood. As long as IGF-1 is bound to this protein, it can’t interact with tumors to spread them throughout the body.
Weight training also reduces systemic inflammation, which is an underlying cause of cancer. Other mechanisms include a modulation of sex hormones, heightened antioxidant defense mechanisms, increased immune system vigilance against incipient tumor formation and reduced bodyfat.
Ruiz, J.R., et al. (2009). Muscular strength and adiposity as predictors of adulthood cancer mortality in men. Cancer Epidemiol Biomarkers Prev. 18:1468-76.