Some of the terminology used here is explained more fully in my previous post about polarized training. Be sure to read that first.
Our lives revolve around a seven day cycle, the infamous week. Between work, family, and friends, the best we can hope for is six workouts a week without resorting to two-a-days. If we schedule one hard day and the remaining days easy, we get close to 80/20.
In his landmark book “Fast After 50,” Joe Friel makes a case that aging athletes should do two hard workouts per week, one aerobic capacity (very hard) and one lactate threshold (moderately hard). He also makes a point that aging athletes need more recovery time. In true Friel style, he offers a solution that even he admits is awkward, a nine day training cycle. If you are old enough or wealthy enough to be free of a rigid work schedule, this might work for you. For most of us, a constantly shifting routine, with long runs and long rides coming on different days week to week, is impractical.
What I suggest also comes from the same book. Create a seven day framework that spreads hard days one or two days apart, then fill in the rest with easy workouts with the understanding that there will be a day here and there where you know you need more rest. The agreement is to listen to your body and not be a slave to your training plan.
The framework I use is this:
Mon - rest
Tue - Aerobic Capacity (AC) high intensity, high stress
Thu - Lactate Threshold (LT) high intensity, high stress
Sun - Aerobic Threshold (AT) (Long bike or run) low intensity, high stress
Wed, Fri, Sat - (AT) low intensity, low stress
High intensity days = 2
Low intensity days = 4
There is a bit more work to turn this framework into a training plan. Each type of workout gets a dose. I never do two high dose, high intensity workouts in the same week. It would be much more likely to pair a high dose AC workout with a low dose LT workout, or vice versa. When aerobic threshold work takes priority, the AC and LT workouts will pull back to medium or low dose.
This is not exactly 80/20. More like 60/30. If I had more time to train I might be able to reach 80/20, but for an aging athlete there is only so much stress the body can absorb. The issue here is that those two high intensity workouts are there to hold back the effects of aging.
The 3 - 3 - 3 Rule
A different kind of framework that can be superimposed on the above is the 3 - 3 - 3 rule. The goal is to balance the three modalities that make up triathlon by doing an equal number of workouts a week in each discipline. Ideally they should be spaced evenly, but due to constraints such as available swim times and other commitments, this is not always possible.
As I said earlier, you are limited to six workouts per week without two-a-days. That will mean using 2 - 2 - 2. This is enough work for a senior athlete to stay healthy and minimize the impact of aging, but to excel in sport there is much agreement that it takes three sessions a week to make progress. If you are new to any of the three triathlon sport modalities, those three additional sessions should all be about technique, with very low intensity.
This is my framework. Yours might look a little different, but there are only so many hours in a day, and days in a week, so the possibilities are not exactly unlimited. Sometimes you just have to juggle. The point is to do the best you can to balance your workouts and get just enough high intensity work while recovering well each day.
Bottom line: Doing more hard work is not the way.