Thirsty (for knowledge) Thursday: a New Take on the "10%" Mileage Rule

An interesting article caught my eye in the recent Runner's World, and then I saw that they posted it online 2 days ago. It's a new take on how to safely increase your milage. Here are a few bits of it:

If you get injured, you must have been running too much, right? Recently, sports scientists have been rethinking this belief. In some cases, hard training may act as a “vaccine” against injuries by toughening up your body—so doing too little can be as risky as doing too much.

That doesn’t mean you should crank up your mileage immediately. Instead, focus on the balance between how much you’re running now and how much running you’ve done over the past month. By tracking this “acute-to-chronic” ratio, you guard against the twin perils of too much and too little.

Calculate the ratio. The acute-to-chronic training ratio compares your mileage for the last week to your average weekly mileage for the last four weeks. If you’ve run 50, 40, 50, and 60 miles in the past four weeks, your ratio is 60 (last week’s mileage) divided by 50 (average of last four weeks). That’s 1.2.

Here's an example of that from their magazine:

In recent studies with athletes from various sports, injury risk climbs when this ratio exceeds 1.2, and increases significantly when it exceeds 1.5. This is a more sophisticated version of the old 10 percent rule: If you increased your mileage by 10 percent each week for four weeks, you would end up with a “safe” acute-to-chronic ratio of 1.15. But by looking back for four weeks instead of one, the ratio protects you from overdoing it after periods of missed or reduced training, which leave you more vulnerable when you resume your normal routine.

Consider intensity. How much you run isn’t the only factor that affects injury risk, because races and hard workouts take a greater toll on your body than easy runs do. You can account for this by calculating a training load ratio. After each run or workout, rate the overall intensity of the session on a scale from 1 to 10. Then multiply that rating by the total duration of the run in minutes to get a more comprehensive measure of training load. For example, a 40-minute run at an effort level of 6 would produce a training load score of 240. Now calculate your acute-to-chronic ratio but using weekly totals of training load instead of miles.

I seriously, SERIOUSLY might try that last part. Intensity and mileage have always been an issue for me, and this seems to be an way to calculate both to see how much I'm "taxing" my body.

Finally, they end with this:

Personalize it. You can think of a ratio of 1.2 as a yellow light and 1.5 as a red light. But every runner is different, so what applies to the mythical “average” runner may not apply to you. This approach will be most valuable if you keep track of your changing ratios over several seasons while making note of injuries—not just major ones, but also minor aches and nagging pains. Eventually, you’ll discern patterns that tell you which ratios your body can tolerate and which ratios trigger problems.

The obvious time to be careful is when you’re pushing your mileage or intensity to new heights; keeping the ratio low will help you do it safely. But be alert for patterns at the low end, too. You might find, for example, that whenever you let your mileage drop below 20 miles for two weeks in a row, your acute-to-chronic ratio spikes a few weeks later when you get back to normal training—and that you often get injured as a result. You can’t always avoid injuries, but by looking for patterns, you can at least avoid making the same mistake twice.

They actually put up a calculator for this on their website. So you can go here and just plug in 4 weeks of training totals, and it will give you your ratio. Check it out.

For more "Thirsty Thursday" posts that highlight workouts, body science, and all kinds of interesting information, CLICK HERE. Back with some "Friday Funnies" tomorrow. :)