A few key workouts per week are all you need to improve performance—that’s the essence of the 90-10 rule
In business, there is a principle called the 80-20 rule, which states that 80 percent of business sales comes from 20 percent of its clients.
In endurance sports, there’s the 90-10 rule.
Depending on the distance, most endurance events are around 90 percent aerobic (endurance) and 10 percent anaerobic (intensity). The 90-10 rule recommends that training should reflect the same relationship between easy and hard sessions. Although not quite the same, both rules prove the Law of the Vital Few. Just as a business can prosper with a few clients, an athlete can perform well on a few key workouts per week.
When I make training programs for my students, I schedule one hard session per sport every week for two to three weeks, after which I schedule a week-long recovery period. During this time, the only hard sessions are the time trials. If possible, I try to emphasize one sport per week or month such that the key workouts for the other two sports are less intense.
The build period is when both volume and intensity are high and consequently when an athlete’s risk of overtraining is high as well; I make sure to stay in this period no more than six weeks plus two weeks of recovery.
Many athletes make the mistake of reversing the 90-10 rule.
I see this a lot in my highly motivated and competitive students. They insist on focusing all their energy on hard workouts week after week at the expense of easy endurance and recovery sessions. I warn them about the consequences of this skewed approach to triathlon training. Some listen but those who refuse to back down end up getting sick or injured before a big race. They throw away months and months of hard work and money because in the end, they fail to make it to the starting line.
I apply a more conservative yet still scientific approach to coaching because I’ve experienced its effectiveness firsthand. The only time I overtrained in my entire career was when I had to work with a coach whose style was more like that of a drill sergeant. It’s possible for his bootcamp style to work for some, but I find that being guided by the 90-10 rule ensures an age-grouper’s longevity in the sport.