About the researchers
Heather Ohly is a Registered Nutritionist who is married to Shane Ohly, the organiser of the Dragon’s Back Race™. As a keen runner herself and with some previous experience of research at mountain running events, Heather was keen to study the nutrition strategies and energy balance of competitors during the 2012 event. She enlisted the help of Nils Swindell, an undergraduate Nutrition student from Plymouth University, who assisted with data collection and analysis.
Ultra-distance running in the mountains creates a unique challenge in terms of achieving energy balance. The action of running often makes eating difficult due to loss of appetite, lack of palatability or gastrointestinal discomfort. Add to this the challenges of carrying your own food, with minimal support points, and making decisions about weight versus calories.
The main aim of this study was to measure the energy and nutrient intakes of competitors and compare these with performance. It is not possible to draw conclusions about the effect of nutrition on performance from this kind of observational study, but it may be interesting to see how the nutrition strategies of the faster competitors compared with those of the slower competitors.
|Chips and Ketchup! Mark Ford tucking into a high carbohydrate snack at the end of day three. Photo: Rob Howard / SleepMonsters.|
Competitors were recruited via the event website and emails from Shane. At registration, they were provided with information sheets and the study methods were explained. Each competitor signed a consent form and understood they could withdraw from the study at any time.
Heather and Nils measured all of the food consumed between the start line (Monday morning) and the finish line (Friday afternoon). As the event caterers provided breakfast, afternoon snacks and evening meals, this simplified matters because everyone was choosing from the same options. The items selected were recorded and weighed. Competitors were asked to keep hold of their food wrappers so that ‘race food’ could be recorded at the end of each day. Some competitors kept a list; others provided recipes for homemade items.
After the event, the weighed food inventories were entered into nutrient analysis software to provide a detailed breakdown of energy and nutrient intakes for the whole five days. The focus of the analysis was macronutrients (i.e. carbohydrate, fat and protein) since these are the nutrients that provide energy. Race food and camp food were not analysed separately because it is the combination of both that sustains a runner during a race of this length.
Energy expenditure (EE) was estimated using the following formula:
Total EE over 5 days (kcal) = (BMR x 5) + (EE whilst running x race time in min)
BMR is basal metabolic rate, the amount of energy expended daily at rest. This formula and its components take into account the following variables: height, weight, age, gender and average running pace. However, it does not take into account the additional energy expenditure due to ascent, rough terrain, weight of rucksack and climate. All of these factors varied throughout the race and there were also individual variations in route choice (distance and ascent) not accounted for in this study. Therefore, this estimate of energy expenditure should be considered an underestimate.
|Rob Baker relaxing - with a packet of his favourite crisps - at Carreg Cennen Castle after finishing the fifth and final day. Photo: Jon Brooke|
A total of 16 competitors were recruited into the study and provided data during the event. However, six of these competitors did not complete the whole event. In order to fairly compare energy and nutrient intakes with performance, data is presented (in Table 1) for the ten competitors who completed the whole event. They are listed in order of performance and grouped into faster, medium and slower groups for comparison.
The slower competitors consumed greater quantities of total energy, carbohydrate, fat and protein over the five days of the race, compared to the faster ‘elite’ competitors. This is interesting since they all completed the same distance and ascent (approximately) but the faster runners were on the hills for less time.
Estimated energy expenditure was slightly greater for the slower competitors than for the faster competitors (average 325 kcal per day). This is mainly due to the extra time spent running. Average pace during the race is accounted for in the formula, so the faster competitors would have expended more energy per minute of running.
Subtracting energy expenditure from energy intake, we can see that the faster competitors experienced greater energy deficit during the race compared to the slower competitors – in fact more than double the energy deficit in calories.
Important note: One of the faster competitors consumed considerably less energy and nutrients than everybody else according to his food records. This has skewed the results and without his data the results would be less striking.
Elite mountain runners in this race were able to sustain their performance despite experiencing greater energy deficit compared to the slower competitors. This is likely to be due to higher levels of fitness, training adaptations and experience in choosing the optimal food for their needs. The extent of the effect of nutrition on performance requires further study in ultra-distance mountain running events.
Thank you to all the competitors who took part in this study and to everyone who helped and accommodated us at the event.