A lot is known about protein needs for strength and power athletes such as swimmers, gymnasts, track athletes and wrestlers. Lean muscle gain is a well-researched topic. There is less certainty about the amount of protein that will optimise training and performance for endurance athletes. This is because the primary emphasis for stamina-based sports is carbohydrate or glycogen sufficiency. Also, most of the studies done on protein needs for endurance sport have used young male adults as test subjects, so that data may not be as useful for female and masters’ athletes.
Here I’m going to outline what the current research has to say about protein requirements. In part 2 I’ll discuss protein sources and how optimise your protein intake for training and recovery.
Protein is important for muscle building and repair. It’s also critical for internal processes such as forming the cells that transport oxygen and the hormones which regulate key bodily functions; creating enzymes which effect chemical reactions and antibodies for immunity; and regulating fluid balance and the acid/alkaline balance in cells.
The protein you eat comes from both animal and plant sources. It’s broken down in the digestive system into amino acids which are pooled in temporary storage, waiting to be made into internal body proteins. You need 20 amino acids for building these internal proteins and nine of these must come from the food you eat – they’re called essential amino acids. Animal food sources like dairy, eggs, fish and meat contain all of the essential amino acids, making them complete protein sources. Plants are incomplete protein sources as they typically contain only some of these essential amino acids. For this reason, non-meat eaters need to have a variety of plant foods during the day for their bodies to achieve a pool of the essential amino acids.
Your body doesn’t store excess protein, so any amino acids that aren’t used within a limited timeframe become transformed into either glycogen or fat. It’s thought that there’s an upper limit to how much protein the body can use each day and any more than this isn’t beneficial. In fact, a high protein diet isn’t advisable as it can become toxic for the body, causing symptoms such as nausea, dehydration and very smelly sweat.
How much protein do you need as an endurance athlete?
Endurance athletes need to consume enough good quality protein to:
- Support normal body processes,
- Supply the increased amino acids required for post exercise muscle recovery, and
- Replace lost leucine (this is an essential amino acid which is significantly depleted with endurance exercise).
Protein needs are best determined by a weight measurement, rather than a percentage of calories.
For general health maintenance the recommendation is around 0.8 to 0.9 gram of protein per kilogram of body weight each day.
There’s no agreement on the optimal amount of protein that will achieve specific endurance training performance goals. The research I’ve looked at suggests a range of 1.2 to 1.8 grams of protein per kilogram of body weight each day, although some authors suggest an intake of up to 2 grams. It would make sense then to eat at the lower end of the range in off season, or low volume and intensity training periods – and to eat at the higher end when training volumes and intensities are high.
For example, a 75kg male athlete training 4 hours a day at aerobic pace should aim to eat 1.7 grams and up to 2 grams per kilogram of bodyweight, which is 128 – 150 grams per day. A 55kg female athlete training 60 minutes a day at moderate to high intensities should aim to eat 1.4 to 1.6 grams protein per kilogram of bodyweight, which is 77 – 88 grams per day.
In order to achieve these protein targets, you should include smaller amounts of a variety of proteins with your meals and snacks throughout the day, rather than consuming it all in a couple of large portions.
This is because different proteins have different absorption rates. Some are taken up by the muscles quickly (eg. whey and soy isolate powders) and others are slow release (eg. casein powder, yogurt, eggs, nuts). Your muscles can take up to 48 hours to repair after strenuous exercise. If you consume a lot of fast absorbing protein immediately after exercise this can negatively impact the muscle repair process as it will peak quickly and then drop off. Ideally you want to maintain a state called ‘positive protein balance’ where muscle repair and gain is greater than muscle breakdown. You do this by eating a mix of proteins throughout the day.
So, what are the optimal protein sources for both meat eaters and plant-based eaters, and how can you ensure that you’re getting enough protein at the right time to boost both your training and recovery?
In Part 2 I discuss all this in detail. You can find it here.