Evidence / Health / Uncategorized

The Unknown Knowns: 4 Myths about Health and Exercise

We’re pretty good at knowing what we know and don’t know. But the trouble lies in deciphering the truth in what we think we know. To that end, I set out to debunk 4 health and exercise myths that have been perpetuated despite a wealth of accumulating evidence refuting them. In no particular order or category, I bring you:

Picture taken from www.globalfit.comMyth #1: Exercising after dinner or late at night disrupts your sleep.  Survey data from 1000 adults on indices of sleep quality support that evening moderate or vigorous exercisers do not differ in sleep quality relative to non-exercisers. These evening exercisers also reported equal or better sleep on the days they exercised vs. the days they didn’t. While morning vigorous exercisers had the most favorable sleep outcomes, evening exercisers didn’t appear to suffer from their nightly physical activity, a finding that has been established in laboratory studies of late-night cycling exercise as well as at home investigations involving running.

Myth #2: Anyone can exercise if they just have the willpower to do it.  Exercise adoption, maintenance, and adherence have multiple influences, including genetics. For example, genetic variants in angiotensin converting enzyme (ACE), which is involved in blood pressure regulation, influence adherence to exercise training over 6 months. Similarly, candidate genes associated with the dopamine and serotonin systems (neurotransmitters that play a role in mood and behavior) have also been linked to exercise adherence in college students. There are also myriad non-genetic factors, including social support, exercise self-efficacy, environment and education, that contribute to compliance with routine physical activity.

Picture taken from www.progressive-charlestown.comMyth #3: The United States is a healthy country. We’re a healthy country if you compare us to a developing or emerging country. But relative to our developed international cohort, we’re at the bottom of the heap in terms of longevity, morbidity and mortality.  A recent analysis of health and longevity, reports the New York Times, shows that “younger Americans die earlier and live in poorer health than their counterparts in other developed countries, with far higher rates of death from guns, car accidents and drug addiction.”  These statistics contribute to the dramatic differences in American life expectancy (U.S. men rank last and U.S. women rank second-last among 17 developed countries). The health disadvantages of our younger years (accidents, cardiovascular and metabolic disease, smoking, drug use, physical inactivity) explain the discrepant mortality rates observed in our later years.

Myth #4: Data don’t lie. Perhaps data alone are quantitative truthtellers, but the interpretations and analyses that come out of any data set are far more subjective than most of us realize.  A 2010 article suggested that almost one third to one half of our hallmark clinical trials (randomized, double-blind trials that establish links between interventions and outcomes, such as a dietary supplement or surgical procedure on heart disease) may be flawed. For example, in about 40% of studies establishing a major finding, follow-up studies fail to confirm the results of the original study, suggesting that the original publication may be inaccurate or exaggerated. A recent example of this occurrence is found in the new evidence failing to find a direct link between saturated fat and heart disease.  A large study of over 500,000 people “did not find that people who ate higher levels of saturated fat had more heart disease than those who ate less.” Does this mean that you can’t trust science and medicine? Of course not! But perhaps the quote “There are lies, damned lies, and statistics,” can be interpreted as a reminder that we need to exercise caution in defining the knowns and unknowns in science, health and medicine.


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