Personalizing Exercise Protocols Based on Genetics?

Earlier this week, I reviewed ‘The Cure For Everything‘ by Timothy Caulfied, who presented a rather devastating (some would say sobering) view of ‘personalized’ medicine based on genetic analyses. His take essentially is that little (if any) of the promise of genetics for complex conditions has panned out and little (if anything) is likely to pan out in the foreseeable future.

This is not because genes (or rather their expression and function) do not influence virtually all of human structural, metabolic, and perhaps even our behavioural characteristics. In fact it is the very fact that there are countless genes that impart these effects and generally do so in complex harmony (or disharmony) with countless environmental factors, which makes ‘predictive’ medicine at the personal level so iffy.

An example is a recent paper by Roth and colleagues published in Medicine and Science in Sports and Exercise that reviews the latest findings in genetics related to exercise, fitness and performance.

The paper focusses on the highest impact papers such as one that described physical activity levels as being significantly lower in patients with mitochondrial DNA mutations compared to controls (not really a surprise given that exercise is no fun without high-performing mitochondria).

Other studies found strong associations between sequence variation in the activin A receptor, type-1B (ACVR1B) gene and knee extensor strength, with rs2854464 emerging as a possible ‘marker’ of higher muscular strength.

Genetic data has also been associated with aerobic exercise training-induced improvements in maximal oxygen consumption, but no genetic variants derived from candidate transcripts were associated with trainability.

Finally, much of this paper looks at the fat mass and obesity-associated (FTO) gene, which has been associated with a modestly increased risk for obesity especially in sedentary individuals.

Based on these findings (and a few others), the authors rather enthusiastically conclude:

“…that a strong exercise genomics corpus of evidence would not only translate into powerful genomic predictors but would also have a major impact on exercise biology and exercise behavior research.”

This is where the authors lost me (and would likely have lost Caulfield). Undeniable, genetic studies represent an amazing feat of science and teach us much about human biology. But the idea that a genetic ‘test’ will somehow reliably predict ‘performance’, ‘fitness’, ‘training response’, or any other features, may at best be of interest to extreme athletes (e.g. not having the right genes may make the quest for Olympic Gold futile – so why bother?); their application or utility for population health or even that of my patients is far less clear.

Indeed, at some level, the idea of basing a specific treatment recommendation (e.g. a certain type of exercise) simply on the results of a laboratory test, may be the exact opposite of ‘personalized’ medicine, which to me, would be about considering environment, social and cultural background, beliefs, psychology, interests, and a 100 other ‘personal’ characteristics of each of my patients.

AMS
Freeman’s Village, Antigua

Roth SM, Rankinen T, Hagberg JM, Loos RJ, Perusse L, Sarzynski MA, Wolfarth B, & Bouchard C (2012). Advances in Exercise, Fitness, and Performance Genomics in 2011. Medicine and science in sports and exercise PMID: 22330029

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