Not All Hearts Are Created Equal

By Miriam Eisenberg, Member of The George Washington University’s Research Team for the STOP Obesity Alliance

Just recently, The New York Times published an article  on researchers at The Northwestern Feinberg School of Medicine who are reporting that the formula for calculating maximum heart rate, used by millions to track the intensity of their workouts, was actually based solely on data from men and can not be generalized to women.  In fact, the researchers report an entirely different formula for women (206 – (age X .08) = maximum heart rate) than what was found for men and assumed to be accurate for everyone (220 – (age in years) = maximum heart rate.)

This finding is one of many instances in which our health knowledge was based on studies of men and simply generalized to women.  Historically, clinical trials used all male samples and assumed that was sufficient.  The excessive disparity in knowledge about female-specific disease outcomes was not addressed until 1991 with the launch of the NIH-funded Women’s Health Initiative, which employed large samples of women to test prevailing biomedical explanations. 

Dr. David Rowlands at Massey University in New Zealand learned all too well that health information based on men is not necessarily accurate for women with his study on protein-loading after exercise.  Physical trainers normally tell both men and women to protein-load after intense workouts.  However, after conducting studies on men[i] and women,[ii] Dr. Rowlands found that protein-loading improved male athletic performance, but had no effect on female athletic performance and actually made the women feel worse.  He concluded that female athletes only need 0.65 times the amount of protein as male athletes. 

Currently, nearly 65 million American women are overweight or obese.  As public health advocates encourage overweight and obese women to lose weight, it is vital to give them accurate and tailored information.  Weight loss is difficult as it is, and without appropriate guidelines, women will not have the tools and reinforcement that they need for successful long-term weight loss.  For example, while the difference in numbers based on the formula for women and the formula for men may not seem large, it could be the difference between an invigorating and maintainable exercise routine and one that is exhausting and defeating.  By trying to keep one’s heart rate at a level that is not healthy or even achievable in some cases, some women may increase the risk of overexertion and possibly cause injury.

These are just a few of many examples emphasizing the need for health information tailored to women.  The STOP Obesity Alliance recently formed the Task Force on Women to promote health information and research that is focused on specific experiences of women and expanding the information we already know about the causes, treatment and experiences of obesity.  On July 21, the Task Force on Women held a public discussion titled “Can Women Continue Carrying the Weight of the World?” on the barriers to improving women’s health and, subsequently, the health of their families.  One of the main tenets of the Task Force is addressing the unique physiological and biological factors that disproportionally affect women and act as barriers to weight loss.  Without tailored health information for women, the charge of improving women’s health and weight becomes even more difficult and the obstacles even greater.

---

[i] Rowlands DS, Rossler K, Thorp RM, et al.  Effect of dietary protein content during recovery from high-intensity cycling on subsequent performance and markers of stress, inflammation, and muscle damage in well-trained men.  Appl Physiol Nutr Metab 2008;33:39-51.

[ii] Rowlands DS, Wadsworth DP.  Effect of high-protein feeding on performance and balance in female cyclists.  Med Sci Sports Exerc 2010; http://www.ncbi.nlm.nih.gov/pubmed/20508536.  Accessed July 13, 2010.