“The more we do, the more we can do.” William Hazlitt
Winter is the time to build mileage. Build up the distance of your long run, ride and swim gradually. The effort should be at a comfortable level. Usually, this is 80% or less of maximum effort. You need to include at least one long run every three weeks, one long ride on an alternate weekend. In the pool you should work on distance too. Gradually increase the length of your swim to 1.5 times the distance you’ll be racing (for sprint distances, for Half and full Ironman distances work up to race distance). These long swims should be done on alternate weekends from your long run and long ride.
For example – week 1 do a long run, week 2 do a long ride and week 3 do a long swim, week 4 start the cycle again.
During the week alternate medium distance runs, rides and swims with easy days (or days off). It’s usually better to take an Active Recovery Day, than to take a day totally off. This would be a run of 1 to 3 miles at 60-65% effort (of maximum heart rate). A ride of about 30 minutes – an easy spin with friends. The swim should be less than 30 minutes.
The benefit of an Active Recovery Day over a day off is that if you increase the blood flow to muscles the waste and soreness will diminish faster than with total rest.