Water Exercise Is Excellent, But There Are Pitfalls
Popular internet doctor Dr. Joseph Mercola believes that in some ways a water workout may be better than one on land. He explains that the heart rate during aerobic exercise is slower in water than on land because the pressure of the water helps your blood circulate more effectively with fewer heartbeats. He explains:
According to the American Council on Exercise, your heart rate will be reduced by as much as 17 beats per minute compared to land exercise, so be sure to keep this in mind if you measure your heart rate to watch your intensity.
When you’re in the water, your heart rate will be lower than on land, even if you’re exercising very strenuously, so you need to listen to your body, not rely on heart rate, to gauge when you’ve had enough.
Dr. Mercola cautions, however, that water exercise has its pitfalls. Chlorine is a major concern.
Swimming pools typically contain chlorine, he points out, and along with it, disinfection byproducts (DBPs), which are formed when bromide, naturally existent in the source water, and/or organic materials like hair, skin, sweat, dirt and urine react with the large amounts of chlorine used to sanitize the pool water.
DBPs are over 10,000 times more toxic than the chlorine itself and have been linked to DNA damage and cancer. In one study, more than 100 DBPs were identified in pool water, and when researchers measured evidence of genotoxic (DNA damage that may lead to cancer) and respiratory effects on swimmers who swam in a chlorinated pool for 40 minutes, they found:3
- Increased micronuclei in blood lymphocytes, which are associated with cancer risk
- Urine mutagenicity, a biomarker of exposure to genotoxic agents
- An increase in serum CC16, which suggests an increase in lung epithelium permeability
This is a serious issue if you swim in chlorinated pools on a regular basis, as your body absorbs higher levels of DBPs by swimming in a chlorinated pool once than you would by drinking tap water for one week! In fact, in one study on trihalomethanes (THMs), one of the most common DBPs, found the cancer risk from skin exposure while swimming comprised over 94 percent of the total cancer risk resulting from being exposed to THMs!4 The authors even went so far as to conclude that swimming in a chlorinated pool presents “an unacceptable cancer risk.”
As an aside, DBPs are also the likely culprits for the increased incidence of sinusitis and sore throats among swimming instructors,5 as well as the negative impact of chlorinated pools on the respiratory health of children and adolescents. In fact, one study found that in children with allergic sensitivities, swimming in chlorinated pools significantly increased the likelihood of asthma and respiratory allergies.6
This doesn’t necessarily mean you have to give up swimming. Swimming in an ocean is an excellent alternative, as is swimming in a lake or other natural body of water. You can also find a way to keep your pool clean from bacteria, algae, and other organisms without the use of dangerous chemicals.
One of the best solutions is NOT to chlorinate your pool and just use a maintenance “shock” treatment every five or six days, which will kill the algae buildup. The shock treatment volatilizes in about 24-48 hours and gives you a several-day window in which you can safely use your pool. You can also reduce the amount of organic material you bring into the pool, and thereby the amount of DBPs created, by showering prior to entering and teaching your children not to urinate in the water.