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Nutrition for Pool-Swimming – Let’s Talk Energy and Carbohydrates

Energy requirements for swimming

Swimming events can be compared quite well to middle-distance track running as the duration of the races are similar (e.g. 100m swim can equate to a 400m run <1min, 200m swim can equate to 800m run <2min). The duration of such events requires elements of power, speed and endurance to reach performance potential. Though, with swimming being an aquatic sport, there are unique challenges to take into account in understanding physiological demands placed on swimmers such as water resistance and applying propulsion through the water4.

For sprint swim events (200m or less), our bodies rely heavily on energy from our anaerobic (without oxygen) energy pathways. Training for these events often involves using repeated supramaximal efforts to activate these energy pathways and enhance the muscles ability to reach their peak velocities as quickly as possible! When considering nutrition for optimising this energy system, this is largely centred around creatine supplementation as creatine is a key component for our anaerobic energy pathways. You can check out our Creatine Monohydrate here.

For middle-distance swim events (400m, 800m, 1500m), we use both our anaerobic and aerobic (with oxygen) energy pathways. This is where our carbohydrate and fat become key substrates for energy provision. Nutrition here, should be focused around ensuring adequate glycogen stores are available for the start of events.

In all events, there are differences in the energy requirements for many reasons such as:

  • Drag depending on the stroke – according to a study done in a flume, energy expenditure is greater in butterfly and breaststroke than backstroke or freestyle2.
  • Differences in body morphology i.e. height, weight and overall shape between individuals.
  • Speed of swimming and how much effort is being exerted.
  • Swimmers individual degree of technical skill.

So overall, energy requirements vary greatly between the four strokes on top of large individual differences in energy expenditure due to technique and body shape.

Carbohydrate requirements

Carbohydrates are a key macronutrient that our body uses as a fuel source. Research has shown swimmers who failed to increase carbohydrate intake in response to a sudden increase in training volume had greater fatigue, muscle soreness and an inability to complete designated workouts in comparison to others who increased their carbohydrate intake1.

Further to this, when looking at a group of well-trained swimmers, reducing carbohydrate consumption by 10% resulted in a poorer timed performance, whilst increasing carbohydrate consumption by 10% led to performance enhancement over the same distance5. Taken together it is evident carbohydrate plays a role in swimming performance.

However, this does not mean carbohydrate always needs to be high, but when the intensity is higher such as during a threshold session, carbohydrate intake should be increased to enable high carbohydrate availability6. Other training sessions such as drill focused sessions that are lower in intensity, may not be affected as much by lower carbohydrate availability, which is sometimes inevitable when several sessions are undertaken in close succession during training weeks with particularly high training loads.

Further to this, some sessions may even benefit from lower carbohydrate availability as this can lead to greater metabolic adaptations3, but such practice should be carefully programmed into a swimmers training plan to ensure low carbohydrate strategies are used at appropriate times and would not compromise training quality.

Practically, we can increase carbohydrate consumption by using carbohydrate-rich foods during meals and snacks as well as consuming additional carbohydrates before, during and recovery. Our energy range of products provide great carbohydrate-rich supplements that can be used alongside your diet to increase carbohydrate, our GO Energy Bars, GO Energy Bakes and Beta Fuel Energy Chews are all prime carbohydrate-rich snack options!

During exercise, our GO Energy or GO Electrolyte powders can provide carbohydrate for those longer sessions (longer than 90 min). Consuming carbohydrate during prolonged exercise will provide additional fuel when energy stores start to deplete, which can help maintain blood glucose and prevent fatigue.

Nutrition for competition

Nutrition for a gala should consider both the nutrition-related factors that underpin fatigue in the event or competition schedule, whilst also managing the practical issues of the competition environment. A competition-day nutrition plan should include familiar meals/food where possible, remember the golden rule of nothing new on race day! This is not always possible if travelling for an event but worth keeping in mind.

A high-carbohydrate meal should be consumed 1-3 hour before warm up. After this and between events on the same program, carbohydrate containing drinks such as GO Energy or GO Electrolyte and light carbohydrate foods such as GO Isotonic Energy Gels, bars or bakes to help maintain energy levels and prevent hunger.

If having a meal at the event i.e. lunch before an afternoon session, this should be high in carbohydrate still but consider the portion size and what is likely to cause bloating or gastrointestinal upset, this will vary between individuals but again the key is to use familiar foods where possible.

Caffeine supplements can also be used around competition to increase alertness, products such as our GO Energy + Caffeine Gel, but only use if you are used to consuming caffeine and do not exceed the maximum dosage.

As an example, see below for a timeline for nutrition of an athlete swimming a 100m freestyle, 400m freestyle in the morning session then 2 relays in the afternoon session, the first being 50m freestyle, the second being 200m freestyle.

A high carbohydrate breakfast should be consumed 1-3 hours before, in this case this athlete is going for oats with banana and honey. After the warm-up they should be staying hydrated and sipping on a water bottle containing  GO Energy Powder in time for the 100m free. Once this is finished, they can consume an GO Energy Bake to curb any hunger cravings and keep energy up. 30 min before the 400m free they can consume an energy gel to give a boost pre-400m.

At lunch this athlete is consuming a familiar pasta dish that they know won’t cause them any gastrointestinal distress. Again, they are continually sipping on water bottles containing carbohydrate throughout. They will then compete in relay 1 (50m free), then finally 30 min before relay 2 (200m free), the swimmer can have a final energy gel but this time with caffeine as they are starting to feel mentally fatigued, and caffeine is something they are used to consuming.

This is purely an example of how carbohydrate sources can be used and at what points during a gala, but a lot of choices on what to consume will come down to personal requirements and preferences.

The focus of this article is on carbohydrate, protein and hydration are also important for swimmers, so watch this space for further information on those areas!


Take home messages

  • The energy requirements for swimming varies drastically between distances, strokes and individuals.
  • Carbohydrates are key for training and competition, any low-carbohydrate strategies should be planned carefully so not to affect training quality.
  • At galas, familiar foods should be used to minimise gastrointestinal upsets and carbohydrate should be provided in small but regular intervals throughout the competition to maintain energy levels and prevent hunger.

Overall, nutritional support for competitive swimming should be based around the energy requirements of training and competition and some supplements as mentioned above could be used to develop peak performance. However, if under 16, here at Science in Sport we do recommend a food-first approach and it is to be noted that all of our products are developed around nutritional recommendations for adults. We would also advise against caffeinated products.


  1. Costill, D. L., Hinrichs, D., Fink, W. J., & Hoopes, D. (1988). Muscle glycogen depletion during swimming interval training. Journal of Swimming Research, 4, 15-18.
  2. Holmer, I. (1974). Energy cost of arm stroke, leg kick and the whole stroke in competitive swimming styles. European Journal of Applied Physiology and Occupational Physiology, 33, 105-118.
  3. Mujika, I., Stellingwerff, T., & Tipton, K. (2014). Nutrition and training for adaptations in aquatic sports. International Journal of Sport Nutrition and Exercise Metabolism, 24, 414-424.
  4. Pyne, D. B., & Sharp, R. L. (2014). Physical and energy requirements of competitive swimming events. International journal of sport nutrition and exercise metabolism24(4), 351-359.
  5. Reilly, T., & Woodbridge, V. (1999). Effects of moderate dietary manipulations on swim performance and on blood lactate swimming velocity curves. International Journal of Sports Medicine, 20, 93-97.
  6. Shaw, G., Boyd, K. T., Burke, L. M., & Koivisto, A. (2014). Nutrition for swimming. International journal of sport nutrition and exercise metabolism24(4), 360-372.
Written By

Dr Emily Jevons - PhD in Exercise Physiology & Nutrition, Clean Sport Advisor

Emily has worked with Science in Sport since 2021. With a PhD in Exercise Physiology & Nutrition, she currently provides nutritional advice for endurance athletes. Emily not only understands the science behind performance nutrition solutions, but also the physiological and psychological demands of sport after competing competitively in swimming and triathlon for a number of years.