Is exercise a cure-all?
A friend of ours recently sent us an article from the New York Times (see here) discussing whether athletes should eat fat or carbs for performance. Personally I didn’t care for the article but I did read the comments just to see what other people thought. To my dismay one commenter noted that none of this diet stuff really matters because even “health nuts like Jim Fix” keel over while running. I was not familiar with Jim Fixx so I googled him. It turns out Jim Fixx is thought to be one of the key figures in the 70's and 80's that popularized running. Unfortunately he died at the relatively young age of 52 whilst on a run in 1984. (See bio here)
He was a former overweight business executive and smoker who took up running in his mid-thirties. While he did lose a substantial sum of weight (from 220-240 lbs to 170-180 lbs), he had a previous history of smoking (2 packs per day seems to be floating around the internet). Not to mention Fixx had a family history of cardiovascular disease; his father died of a heart attack at age 43. While looking around online I could not find if Fixx had any recommended diet (perhaps it is in one of is books, which I have not bothered to read) but according to John Robbins, Fixx did not believe a healthy diet was that important (here). His belief was shaped by a popular physician in that era, Thomas J. Bassler (see here), who espoused that not smoking and diligently exercising was enough to offer adequate protection against cardiovascular disease although other physicians and researchers at the time presented evidence to the contrary (1).
The story of Jim Fixx reminded me of Micah True aka Caballo Blanco (see bio) as he was depicted in one of my favorite books Born to Run by Christopher McDougall. True also died while running and was only 58 yeas old. True seemed to have led a pretty hard life and with lack of money being an issue for seemingly large periods of his life and may have been a barrier to obtaining high quality food. I don’t know either of these men and can only speculate. I don’t know what their stress levels were, how much they slept, what they ate, etc. The point I hope to make is that exercise alone is not a cure-all!
Unfortunately exercise is portrayed to be a cure-all at times. As an exercise physiologist and enthusiast, I will advocate for exercise all day but it does not make us super human. Furthermore exercise can be a double-edged sword as acute exercise can temporarily put a small percentage of us at increased risk for a cardiovascular event (2,3). There is also some scant evidence suggesting that excessive endurance exercise may be detrimental to cardiovascular health (4). In truth, studies investigating lifestyle, disease incidence and mortality indicate that several factors come in to play when it comes to reducing risk of disease occurrence or premature death (5,6,7,8).
For example a recent prospective cohort study sought to determine the effects of three lifestyle factors (not smoking, healthy diet, and adequate physical activity) on all cause mortality (death). The study team used data collected from 1999-2002 through 2006 from the National Health and Nutrition Examination Survey (NHANES) and the average subject was followed up for 5.7 years. The CDC's National Death Index was used to determine that 745 subjects had died. During this follow up period, individuals who had at least one of the healthy lifestyle behaviors had a 40 % decreased of risk of dying, two behaviors was associated with a 55% decrease, and adopting all three behaviors was associated with a whopping 82% decreased risk compared to individuals who did not have any of the healthy lifestyle behaviors (7). Furthermore adoption of the healthy lifestyle behaviors was associated with significant reductions in incidence of cardiovascular disease and cancer (see table 3)*. These finding have to be taken with a grain of salt considering all the data was taken with the use of questionnaires. People tend to overestimate the amount of exercise they get and underestimate how poor their diets are. Nonetheless prospective cohort studies report these types of findings consistently.
The take home point is that several factors go into lowering our risks of the diseases that plague our post-industrial societies. Epidemiological studies like the one I discussed above give us clues as to what a healthy lifestyle entails and help to shape general recommendations for the public at large, but we are all unique and have our own unique needs to optimize our health. While we all may need to focus to differing degrees on the specifics, we all need to focus on the quality and quantity of our daily food intake, sleep, stress, movement/exercise, and trying to generally enjoy our lives.
*To examine the possibility of reverse causality, the investigators ran an additional model excluding participants who died during the first year of follow-up. In this reverse causality would mean someone on the verge of death abandoned healthy lifestyle behaviors knowing that near death was imminent. See table 4 in the study.