In the Feldenkrais movement class I was teaching the other night I had an interesting discussion with a student who is a parkour instructor at Seattle's Parkour Visions gym. One of the fundamental skills in parkour is jumping with power and landing jumps safely. The instructor was relating some of the ways he teaches these skills and some of the challenges he sees in his clients. In his experience, two big problems are that women tend to land jumps with their knees collapsed inward (a valgus pattern), and everyone seems to have inhibited glutes. About a day after our conversation I picked up the new strength and conditioning research review put out by Brett Contreras and Chris Bearsdley (highly recommended by the way) and immediately noticed that there were two studies (back to back!) that address the exact issues my student was talking about. And the studies suggest some neurological solutions, which I find particularly interesting because that is the theme for this blog. Here they are.
Imagery and jump landing
In the first study, researchers wanted to see whether the use of mental imagery could improve landing technique in a group of women. Many experts believe that the epidemic of ACL injuries in women athletes is partly due to a tendency to collapse the knees inward during deceleration, and the failure to use sufficient hip flexion and knee flexion. With that in mind, they had two groups of women land some jumps while recording data on their joint angles. Then one group received instruction on landing technique from an expert while practicing jumps, while the other group simply visualized landing with better form. They didn't do any jumping at all, they were simply asked to imagine landing with increased hip flexion and knee flexion, and less inward collapse of the knee.
The groups were then retested to assess changes from the baseline. The imagery group made some very favorable and substantial changes in their joint movements - 15% less movement into valgus, and a 38% increase in degrees of hip and knee flexion. And the non-imagery group made no changes at all! Maybe their teacher wasn't very good. Anyway, this is some good evidence for the use of imagery as an aid to performance, which I have discussed previously here.
Glutes and vertical leap
In the second study, researchers looked at whether glute "activation" drills could increase vertical jump performance. It has often been observed that vertical jump correlates well with some other basic measures of athletic ability, such as sprinting. Further, many physical therapists, athletic coaches, and their mixed offspring believe that inhibited glute action is a common cause of poor technique in performing powerful movements such as jumping or sprinting. This problem is sometimes called gluteal amensia, and the common prescription is glute activation drills such as bridges, band walks, fire hydrants, etc.
How did the glute activation exercises come out? Pretty good. Out of three groups that performed three different warm ups before vertical jump testing, the glute activation group did best, outperforming the vibration group by 6% and the general warm up group by 4%. Not earth shattering I suppose, but interesting as a matter of principle.
So how do glute activation exercises make you jump higher? And what gets activated? Activation occurs in the central nervous system that controls the firing of the muscles, not in the muscles themselves. So this is a change to the software for the glutes, not the hardware. Perhaps not a permanent change, but apparently a useful one that can be won at the low price of a brief wake up call to the glute maps. And much easier than going to the trouble of building bigger hardware. (But that helps too.)
Anyone have any interesting experience working on vertical leap? Let me know in the comments.