When it comes to endurance sports, there is a limited number of variables you can address to get faster. You can improve your maximal oxygen uptake with training (VO2max), up to a certain level; you can improve technique in some sports, like swimming; and you can improve your economy.
Running economy is usually defined as the energy required to run at a given (submaximal) speed, and is measured as the rate of oxygen consumption for a given speed (and respiratory exchange ratio). To simplify, it’s your mpg, and you want it to be as low as possible, without lowering your power output (or running speed). After many years of training it becomes very difficult to change your VO2max, especially since you’re also fighting time (after 20, your VO2max declines gradually). Anyone who has spent a decent amount of time in the pool knows that it’s very difficult to change your technique (albeit not impossible). So economy remains. What can we do to improve running economy? Well the good thing is that, there are many things you probably do already that are factors improving running economy. For instance, just running more will increase (to a certain level) mitochondrial density and oxidative enzymes, which in turn are factors positively affecting running economy. You can also go train at altitude, which improves some metabolic processes that essentially help you use O2 more efficiently.
Another thing you can do is plyometrics. There are two (not so recent studies) that show plyometrics will yield improvements in running economy in well trained athletes as well as less trained athletes. Spurrs et al. in http://www.ncbi.nlm.nih.gov/pubmed/12627298 show an increase of close to 3% in just 6 weeks in a group of 17 Australian runners who have been training for 10 years or so, and ran between 38mi and 50mi a week. In the 3k test (just under 2mi) that amounted to an average improvement of 17secs in the test group, with no change in lactate threshold or VO2max.Turner et al. in http://www.ncbi.nlm.nih.gov/pubmed/12580657 showed similar results in less trained athletes. It was hypothesized in both papers that the improvements were due to increase leg-tendon stiffness, resulting in improved store/return of elastic energy. This was confirmed in subsequent studies. Both studies came from Australia…Not very surprising:
So, practically what does this mean? You can’t just go out and start jumping off of boxes, benches etc. because plyometrics are quite taxing, and the risk of injury is high. There are a few books available online that describes good plyo sessions for runners, and if you don’t have a coach familiar with plyometrics, the best thing to do is probably to get familiar with them prior to starting.
If you decide to go ahead:
1. Incorporate them in 2 easy / aerobic runs during the week (maybe just once per week if you’re injury prone). Here http://www.runningplanet.com/training/plyometrics.html is a pretty good list of some of the exercises you can try.
2. Start easy. 15min easy jog warm-up, 15min session, 15min cool down.
– 3x20secs running bound with 1min easy in between
– 3×5 repeats of double leg forward hops with a min easy jog in between
– 3×20 reps per leg of single leg forward jumps with a min easy jog in between
3. Test the first session and see how your legs feel the next day. If fine, then try a second session in the same week.
4. Be careful when increasing the repeats, and adding other exercises.
Your last option is wait for 6 weeks and see if I’m injured or faster.