How Should I Warm-Up For My Triathlon?
Or should you at all? It's almost standard procedure, and evidence backs it up, that for the individual sports of swimming, cycling and running you perform the exercise for a some time before the gun goes off. The benefits are not only physiological— higher oxygen uptake, lower lactate concentration and higher blood pH when the work is preceded by active warm-up—but a thorough warm-up is also thought to prevent injury. However, a 2012 study looked specifically at sprint triathlon and found no difference in performance either in the swim, or subsequent total triathlon times, in those that warmed up and those that didn't. I suspect the swim of the test event was in a pool, and the subject pool was small and amateur, so I still tend to think that a warm up is a good idea, especially for the shorter events. I've read that many pros don't warm-up at all for half or full Ironman length events and I would tend to agree with that as long term energy conservation is key there. But for the shorter distances let's break it down:
There's a couple of reasons why I think the swim warm-up is the most essential of the three. One, it's the first event and your swimming specific muscles won't have time to "cool down" before the real work takes place. Two, the way wetsuits work to keep you warm is the layer of water between your skin and the wetsuit warms up with exercise. The only way to get it warm before your race (a-hem) is by being active with it in the water. Unless it's absolutely freezing in the water I'd encourage you to get in. Also, it does wonders for any pre-race nerves.
While real swimmers might warm up for 1500 meters before a race I think about 400-600 yards for a moderately trained triathlete for a total of about 10 mins is enough to get the benefits. I try to finish the warm up about 5-10 mins before the gun goes off. If you're not allowed to swim before the race, or have to get out 30 mins before and wait in the cold, it might be best to forgo the swim warm up altogether and just content with some jogging around and some windmills with your arms to warm up the shoulder joints.
There's probably limited benefit physiologically to a bike warm up especially for the longer distances. I doubt your cycling specific muscles will "remember" anything by the time you get to the bike. If there is a benefit it's worth doing it as close as you can to the swim start (within an hour of the start time). There are other reasons to do a bike warm-up and they are course familiarization and making sure your equipment is ready. Having a look at both the transition entries and exits from your bike, as well any tricky technical parts of the course, if you weren't able to do it the previous day will probably be worth the energy expended. Also if you knocked your handlebars out of alignment in the car it's best to find out before the race than after exiting T1 (hey, Cecilia!). 10-20 mins is probably enough of a warm-up depending on your experience and training.
Scientific or not I like to do a 5-10 min jog sometime before a race. Again, checking the tension of my elastic laces and just waking the muscles up the morning of I think may help injury prevention when you bolt out of T2. If there's a long wait before the transition area closure and your swim start, bring a 2nd pair of shoes and it'll give you something to do before start time. If it's a beach start, and I can't get in for a swim, getting a bit sweaty in the wetsuit with a beach jog may help warm it up before the race or prevent an injury from the initial sprint into the waves.
In conclusion, I definitely try to do a swim warm-up and sometimes a bike and/or run before most short distance races. While the physiological benefits might not be proven there are some psychological and tactical reasons to get moving before your triathlon.