Protein timing for endurance athletes: how much, and when
Protein timing for endurance athletes has been argued about for two decades, mostly by people selling shakes. The short version: total daily protein matters a lot, and the 30-minute window after training matters much less than you were told.
That doesn't make timing irrelevant. It makes it a secondary lever you pull once the primary one is sorted.
Total daily intake comes first
The International Society of Sports Nutrition puts the useful range for physically active people at 1.4 to 2.0 grams of protein per kg of body weight per day (Jäger et al., JISSN 2017). Endurance athletes in heavy training blocks sit comfortably in the middle of that, around 1.6 g/kg.
For a 70kg athlete that's 112g a day. Spread across four eating occasions, roughly 28g each. Most people training seriously are somewhere near this already, or they're 20 to 30 grams short and don't know it.
Work out your number before you think about anything else. If you're under it, no amount of clever timing will compensate.
The anabolic window is wider than advertised
The idea that you have 30 to 45 minutes post-session to get protein in or lose the adaptation came from early studies that mostly used fasted subjects. When Schoenfeld and Aragon reviewed the literature and controlled for total daily protein, the timing effect largely disappeared (Nutrient timing revisited, JISSN 2013).
Muscle protein synthesis stays elevated for around 24 hours after a hard session, and longer after eccentric-heavy work. The window is closer to a garage door than a letterbox.
Practically: if you eat a proper meal within a couple of hours of finishing, you've done the job. Sprinting home to drink a shake in the car park is not the difference between adapting and not adapting.
Where timing does earn its place
Three situations where it genuinely matters.
Two sessions in a day. If you're running in the morning and lifting in the evening, the gap between them is short and glycogen resynthesis is the priority. Protein alongside carbohydrate in the first hour after session one is worth doing, mostly because it gets you eating rather than because of any anabolic magic.
Training fasted. If you train early on an empty stomach, you finish in a genuinely catabolic state. Eating sooner rather than later is sensible here. This is the scenario the original window research was closest to modelling.
Pre-sleep. 30 to 40g of a slow-digesting protein before bed increases overnight muscle protein synthesis. This one has held up reasonably well in the literature and costs you nothing to implement.
Dose per meal, not just per day
Muscle protein synthesis responds to a dose of roughly 0.3 to 0.4 g/kg per meal, which is around 20 to 30g for most athletes. Beyond that the response plateaus, though the extra protein is still used for other things.
So four meals of 30g beats one meal of 120g, even though the daily total is identical. Endurance athletes tend to get this wrong in the same direction every time: light breakfast, light lunch, then a huge dinner. Front-loading the day is usually the easiest fix available.
Collagen is a different job
Worth separating out, because collagen gets lumped in with protein powders and the two do different things. Collagen is a poor source of complete protein for muscle, low in leucine and missing tryptophan. It's not competing with whey for that role.
Where it has evidence is connective tissue. Studies on collagen taken with vitamin C around an hour before loading show improvements in tendon and ligament collagen synthesis (Shaw et al., Am J Clin Nutr 2017). For Hyrox athletes putting repeated load through Achilles and knees across a race season, that's the relevant use case.
Our bovine collagen is unflavoured, 300g, £18.99. Add it to your daily protein rather than counting it towards your protein target. More on the mechanism in our piece on collagen for athletes.
Race week and race day
During a taper, training volume drops and your protein requirement drops slightly with it. Most athletes should hold intake steady rather than cutting, because appetite falls during taper anyway and undereating protein while carb-loading is a common accident.
On race morning, protein is a minor player. Keep the pre-race meal carbohydrate-led and low in fibre, and put 15 to 20g of easily digested protein alongside it if that sits well with you. Test it in training first. Race morning is a poor time to discover something disagrees with you.
Afterwards, eat when you can face it. Carbohydrate first, protein alongside. The adaptation window is still open tomorrow.
The version that fits on a postcard
Hit 1.6 g/kg a day. Split it across four meals of 25 to 35g. Eat within a couple of hours of finishing a session. Add a slow protein before bed if you want the small extra. Use collagen for tendons, not for muscle.
The athletes who make progress on this are the ones who get the daily total right and stay consistent for months. The ones optimising their post-session window while eating 90g a day are solving the wrong problem.