Becoming More Scientific Regarding Outcomes of Exercise

Is it possible to predict outcomes of exercise well enough to be able to prescribe a specific dose of exercise for an individual to achieve a certain outcome in improvement of long-term health? This is an interesting question, and the answer is probably "no" at the present time, given all of the variables involved, such as the state of the gut microbiome, for example. It does seem a plausible goal for the near future, though, given the trend towards the cost-effective collection of ever more biological data from individuals. In the meanwhile, there are likely useful stepping stones towards greater rigor in determining likely outcomes for exercise, such as that noted here.

Research explains that when exercise is personally prescribed based on what is called "critical power," the results show greater improvement in endurance and greater long-term benefits for the individual. The authors define critical power as the highest level of our comfort zone. "It's the level at which we can perform for a long period of time before things start to get uncomfortable."

It works something like this: Suppose two friends have the same Max Heart Rate. Previous understanding of exercise would suggest that if they run together at the same speed, they should have very similar experiences. However, it so happens that when these two friends run at 6 mph, the exercise is easy for one, but difficult for the other. These distinctive experiences at the same speed and same percent of Max Heart Rate are because 6 mph is below the one friend's critical power, but above the other's critical power.

When exercise is below a person's critical power, their body can compensate for the energy challenge and reach a comfortable and controlled homeostasis. However, when exercise is above one's critical power, their body cannot completely compensate for the energy demand, resulting in exhaustion. Traditionally, individualized exercise has been recommended based on a fixed percentage of one's maximum rate of oxygen consumption (VO2 Max) or their Max Heart Rate.

Researchers discovered that prescribing exercises based on VO2 Max as a reference point results in alarming variability in results. There were participants who benefited significantly from the training period and others who did not, even though the training was personalized to them. They compared this to each individual's critical power and found that it accounted for 60% of the variability in their findings. If exercises had been prescribed using critical power as a reference point versus their heart rate, the results would have varied less, meaning the training sessions would have been more effective and beneficial for each participant. Using "critical power" is a better way of prescribing exercise because it not only accurately serves athletes and those in great shape, but it also serves those who are older or have a more sedentary lifestyle.


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