I love the internet, e-mail and on-line communications of all sorts. You can never get away from the ones you with which you want to remain in contact. One of my good friends, Preston, shot me a note which I got to chew on while I was on a job assignment in Austin, Texas. Nothing like thinking about someone else's discomfort to take you away from your own, right?
"Michael: I suspect I sprained my anterior cruciate ligament during a speed workout a couple of nights back. I was doing some tempo repeats, 2 minutes at tempo with 1 minute recovery, down an underpass (downhill). That is when I believe the sprain happened. The knee doesn't hurt too badly when I run; there is no swelling, just a slight, dull pain when I extend my leg and foot fully. Besides R.I.C.E. (rest, ice, compression, elevation) what else can I do to help the issue? If I shouldn't run, how long should I stay off? If I can run, how much? Thanks!"
The first problem with answering e-mail questions about injuries is this: I'm not a medical professional by any stretch of the imagination, I've not even played one on television. That's why when it comes to running injuries I always prefer to lay out the advice of "check with a medical professional if the symptoms persist, and please let me know what it is if it isn't what I thought." I like to know where my thought process went a little awry, you understand what I mean?
Secondly, I have to read much into the question without knowing what the athlete has done on the outside, how long the injury really has been around, and stuff like that. Since the pain wasn't described as continuous, from what I could read into the question it sounded like a grade two ligament injury, as described in Timothy Noakes' (fourth edition, 2001) "Lore of Running." That obviously means the injury has been around a little while. It probably first showed as discomfort which would occur a few hours after the run and was ignored.
This is nothing new. We all have varied levels of tolerance to pain. Our society tells us to "buck up and suck it up" on a daily basis. I'm a weenie when it comes to pain; the person I'm training, however, could be the type who won't stop running until a bone is sticking out of their lower leg - even then they're going to ask whose bone was stuck into their lower limb. I've seen it; the young woman in question is now, as described by John L. Parker, Jr., "once a runner."
Preston would probably benefit from a week of rest. But, knowing his tendencies - common of every young person who continues to see themselves as bulletproof - would do best to do the typical recovery regimen of icing, compression, elevation, and non-steroidal anti-inflammatory drugs (such as acetaminophen, ibuprofen or naproxen sodium) to relieve the pain.
On top of all this, I'd probably kick him in the butt if I found him doing speed work or hill running over the next three-week period. I would also recommend he back off the training volume (distance/duration) of his running by anywhere between ten and twenty percent. He could ride a bike or use an elliptical trainer...or any non-impact exercise...in place of the decreased training volume, at an intensity which did not cause any knee pain. Better yet, he could use the gym time to strengthen the muscles around the knees, which were probably weaker than he suspected and the weakness was revealed by the eccentric forces of downhill running. Hip flexion work, squats, lunges, standing calf raises, and bridge raises with leg extension top the list.
Once Preston was back onto running, he might benefit from a brief warm-up before exercise, which could be as simple and passive as taking a hot shower, or an active warm-up of very light jogging. A warm-up increases blood circulation to muscles, and makes them more resistant to the forces which can tear muscle bodies. After the light jog, a series of static stretches - for 30-to-60 seconds - of the hamstrings, quadriceps, hip, sartorius, and lower legs would also set him up for a good run. While the defenders and detractors of stretching are still at loggerheads with each other, this can also be seen as an extension of the pre-run warm-up (I'm not a pro-stretch person, but if it works for you...).
And lastly, after about three weeks of no hills, I would recommend a gradual return to hill running, as tolerated, with focus on shorter strides and faster turnover, since the knee pain might have been caused by over-striding.
Like any good "chef" knows, R.I.C.E. is only a part of the injured & recovering runner's "meal." Don't forget to adapt the main course!