Up the pace indoors
If you plan to keep up with some interval work, it might be best to stay indoors. "Intervals and hill reps can be dangerous outside in winter and, anyway, they can be well replicated on a treadmill," says Dewar, though she does not recommend spending more than an hour on a treadmill.
It is important to maintain good form on the treadmill. Matt Sanderson (triathloncoaching.uk.com) BTF level-three coach, makes an interesting point: "I only recommend short treadmill sessions. A lot of people run on a treadmill as if they are walking down a catwalk, with one foot straight in front of the other. We don't advise too much use; it can alter your gait."
If you are sticking to the gym, a good way to maintain motivation is to use multiple brick sessions. These can sidestep boredom and give you a fast-paced, race-specific session that will prepare you for the triathlon season.
Dewar suggests a 20-minute steady bike, followed by 15-minute tempo run, then a 15-minute bike, 10-minute run, and topping the session off with a 10-minute bike and 5-minute race-pace run. The intensity should build as the sets become shorter.
"We would vary this, depending upon the athlete, and the time of year, but it is a good basic example of a session I might set. Winter is traditionally about long, slow sessions but a bit of speed work can be good," says Dewar.