How Not to Get Injured

by Andrew Heffernan on Jul 1, 2009 3:37 PM EDT Comment 3 comments

Eric Cressey has a very clear couple of articles, here and here, on how and why sports injuries happen. The basis of of the articles is this cool formula called the Law of Repetitive Motion. I imagine it's something you learn on Day One of exercise physiology class, but it was all brand-new to me:

INSULT = NUMBER (of reps) X FORCE / AMPLITUDE X RELAXATION

So: the more reps you perform with more force (resistance), the more likely you are to get hurt (insulted); the larger a range of motion you use (amplitude) and the more rest you take, the less likely.

Just makes a guy feel smart to know stuff like this! Like the quadratic equation, it's one of those simple formulas that makes a lot of intuitive sense. The piece that struck me, however, was the "amplitude" factor: the bigger range of motion, the smaller the chance of injury. I suppose that's because, with a full range of motion, no one area in the joint (or muscle or tendon) gets particularly overstressed; the force of the repetition is instead spread out over the joint's entire range.

Cressey mentions sitting, and the formula suggests that the stiller you are--the less you squiggle about like my seven-month-old as you sit--the more likely you are to get hurt: your range of motion is small, you're doing thousands of 'repetitions' (in this case, of the more or less isometric exercise of sitting upright) over the course of a day, and, if you're like most people, you're rarely taking a break. That's three of four factors--lots of reps, small range of motion, and little rest (only 'force' is low), that make continual sitting by itself an activity with a pretty high likelihood of causing injury.

Another great lesson inherent in this formula are four practical steps you can take if a given activity hurts or has caused injury in the past:

1) Do fewer reps.

2) Use less weight.

3) Use a larger range of motion.

4) Rest longer: between reps, sets, and bouts of a given exercise.

Again, good horse sense, for the most part, but a good way of distilling it all down.

0 recs | Comment 3 comments |

Story-email Email Printer Print

Comments

So if you're a runner, you're screwed?

The only option you can choose is option four, and running less miles means running slower.

by LantermanC on Jul 1, 2009 4:53 PM EDT reply actions

I'd say...

…the solution is to balance the running with other activities which require a fuller range of motion and/or opposing muscle groups. Doing some speed (quality) workouts in addition to the LSD runs is definitely viable (larger ROM); water running (lower resistance) is another good option that’s been getting lots of play.

Not my field, but it strikes me that recent literature on the topic has suggested that less mileage doesn’t in fact always mean slower running times.

by Andrew Heffernan on Jul 1, 2009 7:43 PM EDT up reply actions

More on ROM

Writers on this blog have mentioned the Feldenkrais Method® from time to time, and it is applicable here, as well.

From the perspective of the Feldenkrais Method, you’re never just pushing muscles around; you are also changing the brain itself. Athletes recovering from injury (or trying to prevent them) can make rapid progress if they take time to explore a smaller range of motion at a higher quality (more precision, more flow, more ease) rather than continuously maxing out the range, speed, and power of the movement. Your brain and nervous system can only “re-program” with attention and sensitivity, so that you are not repeating the same action that got you hurt in the first place. Starting out doing LESS than your maximum effort lets you escape from the “two steps forward, three steps back” frustration of most recovery processes.

A better kinesthetic sense and improved awareness lead to better self-use and fewer injuries. The Feldenkrais Method is an essential ingredient in any high-performance training program.

by divamover on Jul 13, 2009 11:26 AM EDT reply actions