Personalized nutrition is an approach that is currently attracting increasing interest
in the area of sport and exercise. The prospect of individually tailored, and therefore
more effective, sport and exercise nutrition sounds appealing, but research in this
area is still in its infancy. To compliment traditional analysis of group mean response,
studies are trying to describe the totality of responses by providing individual performance
and health data to an intervention which often show large inter-individual variability.
Emerging evidence indicates that sport nutrition strategies may work in some individuals
or under certain conditions, yet not in others, likely due to a myriad of environmental
and genetic factors, highlighting the necessity in providing a more thorough examination
of results. The current Research Topic aimed to provide a platform for original data
and reviews on novel strategies for personalized sport and exercise nutrition.
The first original article in this Research Topic investigated whether a personalized
hydration strategy based upon sweat rate influenced cardiovascular and thermoregulatory
responses and exercise capacity in the heat (de Melo-Marins et al.). Participants
performed a time-to-exhaustion cycling protocol at 70% of previously determined maximal
workload (~38 min) on three occasions during which they consumed water according to
their sweat rate, ad libitum, or no fluid. Although the personalized hydration strategy
avoided dehydration resulting in lower skin temperature increases and end heart rate,
exercise capacity was not different between sessions. This suggests that although
an individualized hydration strategy may attenuate thermal strain during exercise
in the heat, this does not necessarily translate into performance improvements. Wardenaar
et al. used a novel method to monitor the dietary intake of 5 male ultramarathon runners
during a 120 km race; researchers used bicycles to follow and film the competitors
throughout the race. Large variation in carbohydrate intake was shown between runners,
and consumption was well below the 90 g·h−1 recommendation for exercise of this duration.
Furthermore, only one runner avoided dehydration >2% suggesting that recommendations
should be individualized to optimize personal intakes for future races.
Two studies focussed on individual responses to ergogenic aids. Stautemas et al. investigated
the pharmacokinetics of beta-alanine in blood following beta-alanine supplementation
individualized according to the anthropometric parameters of each participant (10
mg·kg−1 body weight) and compared it to a fixed dose of 1,400 mg. Body weight was
correlated to the pharmacokinetics and explained a large part of the variation in
responses, although the dose individualized to body weight did not reduce this variation
in beta-alanine plasma responses. These data demonstrate that there is a heterogenic
response to supplementation in an anthropometrically diverse sample suggesting further
research is warranted to optimize beta-alanine supplementation. Another study showed
that acute caffeine (6 mg·kg−1 BM) intake increases time-to-exhaustion during a supramaximal
effort without any change in estimated anaerobic energy contribution (Miyagi et al.).
Individual analysis of the data showed that 10 out of the 14 participants increased
exercise capacity above the smallest worthwhile change. Similarly, anaerobic capacity
was modified beyond the limits of the smallest worthwhile change in 11 individuals,
although the direction of change was highly variable; 4 increased their anaerobic
contribution while 7 showed a reduction. Taken together, these data highlight the
individual nature of responses to ergogenic supplements and provides scope for further
work to elucidate the modifying factors behind these differences.
Two review articles were published in this Research Topic, focusing on the optimization
of supplementation with extracellular buffering agents (Heibel et al.) and personalization
of nutrition for athletic performance based upon genetics (Guest et al.). Heibel et
al. highlighted several factors which may modify the ergogenic effects of buffering
supplements such as sodium bicarbonate, sodium citrate and calcium and sodium lactate.
These include the timing and dose of supplementation, factors relating to the exercise
activity undertaken (e.g., intensity and duration), genetic factors, training status
of the individual, and uncomfortable side-effects. The review of Guest et al. outlined
a number of genetic factors that may influence absorption, metabolism, uptake, utilization
and excretion of nutrients, and food bioactives, which may contribute to physical
performance. Specifically, they highlight the current lack of randomized, controlled
trials examining the effects of genetic variation on exercise performance in response
to nutrients and other food components which may direct future nutritional prescription
for athletic performance.
Finally, Swinton et al. provided a statistical framework to support researchers and
applied practitioners alike who wish to determine individual responses to a nutritional
intervention. This narrative review provides an overview of the fundamental concepts
of measurement error and how typical error and confidence intervals can be used to
determine uncertainty in measurements. Guidance on how to assess whether meaningful
changes have occurred following an intervention is then provided, before discussing
the challenges in identifying response or non-response. A modifiable automated spreadsheet
is provided free to download to incorporate personal data sets and readers can follow
the procedures described within the review to analyse their own responses. Importantly,
this statistical framework does not have to be limited to nutritional interventions
and can be applied to any dataset wishing to determine an individual's response.
This Research Topic has resulted in some novel articles that have furthered our knowledge
in the area of personalized sport and exercise nutrition. We hope that this topic
will act as a potent stimulus for further research in this exciting area.
Author Contributions
BS, AE-S, and WD are responsible for the writing of the manuscript. All authors approved
the final version of the manuscript.
Conflict of Interest Statement
The authors declare that the research was conducted in the absence of any commercial
or financial relationships that could be construed as a potential conflict of interest.