Women who’ve had breast cancer surgery needn’t avoid weight training for fear of developing uncomfortable swelling in their arm (lymphoedema). New research shows that weight training may actually cut the risk of this distressing condition, rather than increase it, as previously thought.

What do we know already

Most women have one or more of the lymph nodes under their armpit removed during surgery for breast cancer. Without these nodes to drain to, lymph fluid may build up in the soft tissues of their arm, causing swelling, pain, and weakness. This is called lymphoedema.

The risk of lymphoedema is higher for women who’ve had more lymph nodes removed from their armpit. But even when women have had all these nodes removed, most (up to 87 percent, by some estimates) don’t develop the condition.

Nonetheless, women are often discouraged from lifting anything heavy with their at-risk arm, whether that be a child, a shopping bag, or weights at the gym. As a result, many women steer clear of weight training, which means they miss out on the health benefits of this exercise, such as strengthened muscles and bones.

But does weight training really increase the risk of lymphoedema? To find out, researchers have conducted a year-long study of 154 women who’d had at least two lymph nodes removed during breast cancer surgery. The women were randomly split into two groups: half continued their usual exercise habits, while the other half had weight training instruction at a community gym twice a week for 13 weeks. They then continued doing upper- and lower-body weight training on their own for the rest of the year, gradually increasing their weights and repetitions.

What does the new study say?

Women who did weight training were at no higher risk of getting lymphoedema than those who did not do this exercise. In fact, they appeared to have a lower risk.

Overall, 11 percent of women in the weight training group developed arm swelling, compared with 17 percent of those who didn’t lift weights. The difference was even larger for women who’d had at least five lymph nodes removed. Among these women, only 7 percent of those doing weight training developed arm swelling, compared with 22 percent in the other group – nearly a 70 percent difference in risk.

By the end of the study, women in the weight training group were also stronger and had less body fat than those who didn’t lift weights.

How reliable are the findings?

This was a good-quality study (a randomised controlled trial) and it was well conducted. The researchers made sure the women in the two groups were similar in age, the number of lymph nodes removed during surgery, and other factors that could have affected their risk of lymphoedema. And by following the participants for a year, the researchers were able to assess how weight training might affect women over time, including whether any problems might develop.

Still, we need to be cautious about how we interpret these findings. This study was designed to test whether weight training was safe for women at risk of lymphoedema, not to show whether it can lower their risk. So, although the researchers found that women doing weight training were less likely to get lymphoedema, we need additional research to know whether this exercise might help prevent the condition.

Where does the study come from?

The study was conducted by US researchers in Pennsylvania and Minnesota, and was funded by grants from the US National Cancer Institute and the US National Institutes of Health. It was published in the Journal of the American Medical Association (JAMA).

What does this mean for me?

If you’ve had breast cancer surgery, this study provides strong evidence that weight training won’t increase your risk of lymphoedema, as previously thought. This type of exercise might even reduce your risk, although we need more research to know for certain.

What we do know, however, is that weight training can provide other benefits, such as higher bone density, better flexibility, better posture, and increased muscle, tendon, and ligament strength, which can help prevent injury. And you might also like the way weight training makes you look and feel.

What should I do now?

If you’re interested in starting a weight training programme, be sure to check with your doctor first and enlist the help of an experienced fitness instructor to teach you how to do the exercises properly and safely. In the study, women started training using a very low weight (2 pounds or less, which is under a kilogram) and increased the weight slowly, by the smallest possible increments.

From:
Schmitz KH, Ahmed RL, Troxel AB, et al.Weight lifting for women at risk for breast cancer-related lymphedema. Journal of the American Medical Association. Published online 8 December 2010.