Hill sprints are optimal for developing speed.
Uphill sprints and pulling tires are forms of sprint loading, which is a method of training to improve your running speed and acceleration. Coach Brad Hudson says that the challenge of hill sprints can be equated to Olympic lifts and requires as much explosive power to perform. Resistive sprints -- using an incline or pulling weight -- can increase lower-body strength and improve stride length.
Rocketing Up an Incline
When you perform short sprints on steep hills at maximum effort, the exercise requires an exaggerated forward lean, a higher knee thrust, more hip drive and a fully extended leg during the stance phase. To clear the ground with your lead foot, you have to bend your ankles, knees and hips to a greater degree and push harder with your back foot. The overload imposed by a steep incline puts more pressure on your quads, which work in overdrive to thrust your knee up. All of these biomechanical changes build lower-body power and flexibility as well as improve your stride length and the economy of your stride.
More Muscle, Faster Firing Rate
As a form of maximal power training, hill sprints increase the number of muscle fibers that your brain simultaneously activates. The more fast-twitch muscle fibers you can instantly fire up translates into greater lower-body power for sprinting. While you're tapping into more muscle, you also speed up your motor unit firing rate, or the time between your brain's signal for your muscle to contract and the actual contraction. By shortening this window of time, the muscles in your legs can produce power more rapidly. When you run hills at maximum effort, you're not only conditioning your lower body but also overloading your nervous system.
The Upside of Short and Fast
If you incorporate hill sprints into your training regimen, limit the time of the runs to 10 seconds. By doing so, you can avoid lactate production in your leg muscles and minimize fatigue. According to Bill Foran's book вЂњHigh Performance Sports Conditioning,вЂќ you should be able to run up an 8- to 10-degree incline for anywhere from 10 to 30 yards in 2.5 to 3.5 seconds. When you've finished that first short sprint, you can do another sprint up the same incline, but increase the distance to between 20 and 80 yards. As you grow stronger and more adept at hill sprints, you can tailor your training regimen to match the duration and intensity of race conditions. Because of the effect of overload on your muscles, allow for three days of rest between hill-sprint workouts.
Harnessing Power with a Tire
Pulling a tire is a form of resistive sprinting and can improve your ability to accelerate as well as increase your forward drive and stride length. In contrast to elastic resistance, the relative load of a tire pull is highest at the beginning of the sprint. You have to work hard to overcome the inertia of both your body and the tire. In addition, the tire creates friction with the ground, which adds to the amount of overload. A common rule-of-thumb is to use a tire that's at most 10 percent of your body weight, according to вЂњDeveloping SpeedвЂќ by Ian Jeffreys. An effective tire-pulling workout consists of six 44-yard sprints with 90-second rest intervals between reps.