nutritional demands for triathlon


Demands of the Sport

Triathlon is one of the fastest growing sports in the UK and combines the individual sports of swimming, cycling and running into a single, continuous race. Overall distances and the distances raced in each section can vary.

A triathlon is split into élite and age-group competition. Elite racing is primarily for professional athletes and differs from age-group racing in that ‘drafting’ (reducing wind resistance) is allowed on the bike phase of the race. Therefore, élite triathletes often have the physique of runners, as opposed to top age groupers who develop more powerful physiques to gain advantage during the bike section of the race where a significant amount of time can be won or lost. With three sports to train for, as well as general conditioning training, élite athletes will usually train between 18-22 sessions per week. While this volume of sessions requires structured nutritional practices to support training, adaptation and recovery, the endurance nature of training and racing means that age-group athletes training less than this can also benefit from following nutritional guidelines.

General Nutrition

As described above, the volume of training that is typically completed by a triathlete, whether elite or age group, is high. Therefore, ensuring a suitable energy intake throughout the day is crucial to any sports nutrition strategy. The basis of this is a platform of regular meals. It is normal for many athletes to have three regular meals throughout the day, but for those training hard, it might be advisable to increase the number of meals to 5/6 per day through the inclusion of suitable snacks.

Classically, many documents refer to a specific percentage of carbohydrate, fat and protein that is required in the diet. This is hard to do, and more current guidelines prefer to suggest amounts of carbohydrate and protein based on individual body weight. Unfortunately, these guidelines are not easily transferred into practical meals, so for most participants, it is much easier to emphasise that they should be consuming carbohydrate and protein within all meals. Low glycaemic index carbohydrates are better consumed at main meals, whilst high glycaemic carbohydrates should be consumed in the immediate periods before, during and after training.

Endurance athletes are traditionally sensitive to protein in their diet, based on the myth that it will make them ‘big’. In reality, it is specific training methods (resistance training) that will increase muscle mass, rather than protein intake per se. Protein is crucial in the diet and should be consumed regularly throughout the day to help aid repair, regeneration and general protein balance. Although, the overall protein requirements are unlikely to be as high as strength based athletes, a focus on protein in recovery from training is an area most triathletes can make improvements.

Hydration is another area that requires focus for triathletes. The amount that any individual will sweat is highly individual and dependent on several factors e.g. weather, intensity, duration. Dehydration is known to reduce training intensity, so maintaining a regular fluid intake throughout the day is something that should be maintained. Urine colour is the simplest way to monitor hydration status, with urine that is yellow/colourful suggesting a dehydrated state. Electrolytes (or sodium) are another area that have received significant press in the triathlon world. Consuming a sports drink with electrolytes is recommended practice, whilst for longer events (Ironman) and/or in hot climates, higher electrolyte drinks may be appropriate.

Training Vs. Competition

The training diet is largely about ensuring that the timing of food is good enough to prepare and then subsequently recover from training. Classical guidelines remain the same with a high carbohydrate meal before training, the use of carbohydrate during high intensity and/or long duration training, and the combination of protein and carbohydrate in the immediate recovery period after. However, triathlon is characterised by early morning swims, lunch time runs, and late night sessions just to fit in the training sessions. In these situations, triathletes will have to think on their feet and find snack solutions and pre-prepared meals to overcome these situations.

In theory, competition becomes easier in that races have a pre-determined start time, so it is a routine that can be practiced in advance. Triathlons normally have early starts, so there is an emphasis on a high carbohydrate meal the night before and breakfast that might consist of porridge, orange juice and a banana. The importance of practicing race strategies in training first cannot be overestimated, as the potential to suffer from stomach discomfort can be high. Once the race starts, it can become as much about discipline as anything else. The bike is where nutrition is won or lost, and the use of energy bars, gels and a sports drink provide the energy to recover from the swim and prepare for the run.

Other Considerations

Carbohydrate Loading

Carbohydrate loading for days prior to events is probably a strategy of the past. It is well known that you can saturate the carbohydrate stores in the muscles with 24 hours of a high carbohydrate diet, so a focus on eating well the day before a race is logical. Many tend to eat too much in one go, whereas those who manage to load effectively spread out their food intake into 5/6 meals across the day.


Caffeine has been shown to increase alertness and endurance capacity in athletes; therefore, some athletes may wish to use caffeine in their pre-race nutritional plan. If an athlete chooses to use caffeine in competition it is suggested that (after trials in training) 1-3mg per kg body weight is consumed 60 mins before competition.


Most athletes who are eating a well-balanced diet will consume sufficient vitamins and minerals to meet their nutritional requirements without the need for additional supplements.  However, a good multi-vitamin can provide a useful insurance policy, particularly during the winter months.


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