Injuries and Effects

Expert Discussion Advanced Sprint Training
1

I pulled my hamstring in April and never properly rehabed it. Dumb on my part, for sure.

We did some testing on Saturday and I was a little bit surprised with the results, which I’d like to share and solicit discussion.

My hamstring was still bothering me significantly, though I was able to sprint.
My flying 10 meter times were very bad, each ranging from 0.08 to 0.10 off my personal best split.
However, with the slow motion replay [120 fps], I was able to determine something interesting: my ground contact time was significantly shorter on my right (injured) leg than on my left (uninjured) leg - with GCT averaging 0.10 or less for the injured leg and 0.13 for my uninjured leg.

It wasn’t obvious from the tape because of the lack of a one-meter-markers, but I assume that the injured leg also had a reduced stride length. Though it didn’t feel jerky, the running looks somewhat disjointed when the tape is sped up to normal speed.

I had always assumed that the body tended to naturally compensate for injuries to one side by simply adjusting the other side too - that the body would just reduce the stride length on both sides and even out the GCT. However, at least in this case, it looks like I’m just applying less force (in less time) on the injured leg, and running an uneven stride length pattern. This also runs counter to my expectation that I’d have to have an increased GCT on the injured leg.

Anyone else with experience on this point?
Am I way off, and this is just natural imbalance?

I’m now aggressively rehabing the hamstring and hoping to get back into PR shape.

2

I think this is normal. Your body is trying to protect your injured leg by not applying much force to the ground. Assuming that the injury was in the distal hamstring (closer to the knee than the hip) I’d do eccentric hamstring curls. Most hamstring injuries occur just before touchdown when the hamstring contracts eccentrically to limit knee extension. If there are restrictions/scar tissue I’d also do some cross friction massage.

3

It’s actually about halfway between the hip and the knee.

I injured it early competition period last year and did a bodyweight rehab program I found online, followed up by the series of accelerating 10-20 meter runs protocol that I’ve seen mentioned here. Closed out last year with a PR, actually. The break was pretty good for me in a way.

I like the idea of eccentric hamstring curls. I assume slower and lighter is better?

I anticipated that the body would protect itself, it just seemed to be doing so in a manner that ran counter to my initial expectations: I thought the injured leg would stay on the ground longer to create the same distance - that the body would try to stay in rhythm from a stride length perspective. But thinking about it more deeply, that would really throw off the actual stride rhythm significantly. By simply having unequal stride lengths and adjusting the GCT slightly, there’s not much actual disruption in tempo. The body is genius.