While carbohydrates provide the optimum fuel for energy in the form of glycogen and should make up about 60% of your daily training diet, you also need around 15% of protein to help optimise carbohydrate storage, aid muscle repair, maintenance and growth, and support your immune system.
Triathletes ideally require 1-1.6g of protein per kg of bodyweight, which should be largely provided by a healthy, balanced diet. Protein taken in combination with quickly digestible carbohydrate at crucial feeding times can greatly enhance performance. Before and during a workout, protein will reduce muscle damage and delay loss of muscle strength; immediately after a workout, it will promote muscle recovery and repair, and glycogen restoration. Current theory suggests an optimal combo of 4:1 (4g carbs for every 1g protein), amounting to about 10-20g protein.
Protein supplements such as whey protein are an easily digestible and practical solution for during and after a workout, especially as a protein/carb combo shake. A scoop of whey powder contains 15-22g of protein, so four scoops and that’s your total daily protein requirement.
Over-consumption of protein can result in under-consumption of carbs, which are vital for endurance, and can also raise blood acid levels, leading to the leaching of calcium from your bones and possible osteoporosis. Far better to make your own protein/carb combo by blitzing egg whites with banana and milk.