A rigorous medical study evaluating the benefits and negative consequences of dietary choices requires a high number of participants to produce meaningful results. The summary headlines typically tout findings that say something like 70% of people who did [something] achieved [some positive health benefit.] That data is the basis for general recommendations that are the foundation of good medical advice.
However, we tend to gloss over the fact that simple math reveals that whatever was being studied actually might not have worked for many people. In my notional example above, that was 30% of study participants. So while these large-scale medical studies are great and necessary for universal one size fits all recommendations, what really matters on an individual basis is how it works for a single person.
“N” is the standard scientific notation for the number of participants in a study. Generalized nutritional recommendations are a great starting point for a tennis player looking to achieve peak performance. However, what really matters is how nutritional choices impact each player individually. On a micro level, the optimal number of participants in a personalized nutritional study is 1. In other words, the individual player themselves.
The top senior tennis players have a clear sense of how their nutritional choices impact their on-court performance. Essentially at various levels of rigor and fidelity, they have a lifetime of performing their own N of 1 studies. They don’t discount or disregard broad medical recommendations, but rather continuously test and evaluate how particular practices work specifically for themselves.
For example, many tennis players avoid dairy before competition because it upsets their stomachs. I have never experienced any issue with that in particular. However, I recently discovered that my digestive system doesn’t handle soy-based products very well. If I were to blindly follow the general recommendation to reduce dairy by substituting soy, it would put me in a world of hurt. (In fact, I did that for a while, and it did.)
We live in an unprecedented time of technology that supports data-driven critical evaluation of our nutritional choices and training techniques. Wearable technology such as smartwatches and heart rate monitors are in ubiquitous use during competition. I recently caught sight of a WTA player wearing a continuous glucose monitor during a televised match. Long before COVID raised awareness of devices to measure blood oxygen levels, Taylor Fritz was the spokesperson for a major manufacturer of pulse oximeters.
Tennis players that truly want to achieve peak performance should consider performing N of 1 studies on themselves. We have the ability to collect high-fidelity personalized data. It only makes sense to leverage it to optimize performance. The best players do exactly that.
