Hanson et al matched participants by age, body mass, and running ability in a 10km time trial, which was undertaken seven weeks before the Copenhagen marathon. The study sample size included 14 matched pairs. Each participant undertook their own training program, with the authors reporting that they did not interfere with what each individual had planned. One of the groups freely chose their nutritional strategy, whereas the other group were provided with individualised nutrition advice, based on scientific evidence. Race performance, nutritional intake and gastrointestinal comfort were assessed as outcome measures.
The major findings reported were:
- Those who freely chose their program consumed significantly less carbohydrates than runners using the scientific strategy
- Similar amounts of fluid were consumed
- GI symptoms were similar between groups
- Those in the scientifically chosen group performed, on average, nearly 5%, or 10 minutes and 55 seconds better in the marathon than the freely chosen nutrition group