This isn’t normal, but not unheard of, and might have occurred for a number of reasons.
Firstly, your hydration during the race may have been flawed. Triathletes have always been advised to drink plenty of fluid, as dehydration is a race breaker. But too much water can lead to flushing out electrolytes, i.e. sodium, which in turn can cause edema (the medical term for swelling).
Secondly, you’re putting your body through sustained impact stress for up to 17 hours, which, for some, will cause muscle injury and edema.
To help prevent these two situations, make sure you haven’t overlooked your race fuelling strategy, ensure you’re continually introducing electrolytes through your fluid into your body (take a sweat test when training) and wear tried-and-tested cushioned footwear. Also consider a pair of compression calf guards, as they can alleviate calf soreness and aid venous flow.
Post-race, if on offer, take a saline drip, fully hydrate, rest and where possible try an ice bath and/or sports massage. If the edema hasn’t dispersed after a few days see your doctor, as there might be a more serious underlying factor causing the problem.
Qualified remedial massage and anatomy specialist Kevin works as a sports therapist with both age-groupers and elites.