Reflections on London - The Sports Dietitians Australia Update
There were four presentations on the day, all from the sports nutrition team at the AIS. First up was their Head of Sports Nutrition, Prof. Louise Burke. Louise presented an overview of the thought processes their team goes through each Olympic cycle, and how they decide where to concentrate their efforts from a research and support perspective.
London was quite different to the last few Olympics where Australia had enjoyed so much success - Atlanta, Athens and Beijing all featured heat as a major factor. Athens and Beijing had the added complications - non-English speaking cultures, and dealing with food hygeine issues to prevent athletes from getting sick (especially in Beijing). The only significant challenge anticipated for London was the coincidence of Ramadan during the time of the games, however it turned out that no Australian athletes participated in the Muslim ritual of fasting and feasting.
The insights into the AIS approach to nutrition for an Olympic cycle were particularly interesting. First of all, the team looked at the emerging sports nutrition strategies that warranted further research between Beijing and London. This included:
- More specific use of protein after training to optimise the body's adaptations and recovery
- Using small amounts of carbohydrate (even mouth rinses) to improve performance in high intensity sports of less than an hour's duration. Previous thinking suggested that carbohydrate was unnecessary in such events.
- Increased amounts of carbohydrate (up to 90g an hour) consumed during endurance events such as the marathon and the 50km race walk.
- Deliberately training with low caborhydrate stores in order to maximise training adaptations
- The emergence of new or refined supplement protocols, including beetroot juice, beta-alanine, reduced caffeine doses and combinations of multiple supplements
- Regularly monitoring the Vitamin D status of athletes, and supplementing where necessary
- The use of probiotics to reduce the risk of illness in athletes
- Enhancing recovery from injury via nutrition
Louise went on to present a case study of one of the athletes she worked with, race walker Jarrod Talent. With a new race nutrition strategy (consuming around 90g/hr carbohydrate) Jarrod achieved a personal best in the 50km event and finished with the silver medal, less than one minute behind the existing world record holder (who broke the Olympic Record on the day).
The second presentation was from the AIS Food Service Dietitian, Jo Mirtschin. Jo presented on her experience in London, where she got a last minute call up to cater for 22 members of the Olympic rowing team that were staying together in a rented house next to the event venue. The team chef who was due to do this job had to pull out, leaving Jo with only two weeks to prepare. Jo outlined her approach to menu planning, stock management, and pulling it all together in the kitchen. The rowing team that stayed in the house benefited from what they felt was a much more home-style catering than what they'd experienced, coming off several months of travelling in Europe prior to the games. Three of the crews in the house returned home with medals.
The third presentation was from the Australian Rowing dietitian, Bronwen Lundy. Bronwen presented on the subject of energy availability, and the effect of under-nutrition on the health and performance of athletes. Energy availability is the concept that when energy is used for one body function (eg. in the muscles for exercise) that it is not available for other functions (reproductive function and bone metabolism). If the energy available to the body for those key functions is restricted, hormonal changes (eg. altered or no menstrual cycle in women), a lowered Resting Metabolic Rate and a loss of bone density can result, increasing the risk of stress fractures in athletes, or osteoporosis later in life. In the lightweight rowing squad it was felt that at least two medals may have been lost due to rib stress fractures, resulting from chronic under-nutrition in these athletes who must meet a specific body weight for competition. Whilst this problem was originally thought to only apply to athletes in weight restricted sports (eg. jockeys, lightweight rowers, martial arts, boxing) and aesthetic sports (eg. gymnastics, synchronised swimming), there is now a realisation that this can also be a problem due to large training loads that are not compensated for in the diet (eg. heavy blocks of endurance training in runners, triathletes and cyclists).
The only solution to low energy availablity is to increase the calories in the diet to better match what's being used. Bronwen suggested from experience that any body fat gain can be minimised by very gradually increasing the calories, rather than a sudden, large increase. She also recommended regular (eg. once a year) Bone Mineral Density testing for those who are thought to be at risk.
The final presentation for the day was from Alison Garth. She presented four examples of supplement research and refinement undertaken by the AIS between Beijing and London. Firstly, beta-alanine was studied for its effects with the national swimming team. Beta-alanine is a buffer supplement, allowing athletes to sustain very high intensity exercise for longer. Beta-alanine or a placebo was taken over a ten week training block, and pre and post performance testing occured. Interestingly they found no difference in performance at the end of the ten week training block. Their explanation was that beta-alanine may have allowed the swimmers to push harder in training, but because their training was not adjusted for this the swimmers may have missed out on the potential capacity gained from the supplement. Future studies may focus on whether or not beta-alanine allows athletes to train harder, and if that ends up translating into performance improvements over a period of time.
The second supplement looked at was caffeine. In the mid-2000's a variety of studies emerged suggesting that the large caffeine doses used in earlier studies was not required to achieve performance benefits. The team then went about re-educating athletes, and changing their pre-event protocols to lower the caffeine levels to around 1-3mg per kilogram of body weight, using a variety of sports food products to achieve this (mainly gels and drinks). They even tried caffeinated gum (not available commercially in Australia) with some athletes, but the feedback was mixed. Some people really liked it, other people didn't like chewing gum or reported an unpleasant aftertaste.
The third supplement looked at was bicarbonate. Another buffer, bicarbonate was in regular use with the swimming team, but there was no research available to know whether the pre-race warm up reduced the effectiveness of the taking bicarb before a race. It was found that the warm-up possibly had a small effect on blood bicarb levels, and based on these results the doses and protocols were adjusted for each individual athlete in an attempt to optimise their race performance.
The fourth and final supplement invetsigated was beetroot juice, and the study described above for the teams pursuit was the example given.
Alison finished by looking ahead to the 2016 Olympics in Rio, and focussed on three potential areas:
- How does a combination of multiple supplements change their effectiveness? Are the effects additive, synergistic, or does adding one supplement counteract the effect of another one
- Do some supplements give us the capacity to train harder? And if so, does that actually translate into performance improvements? Should coaches be factoring this into to their training programs?
- What new supplements will emerge over the next four years?