Start with Wall Drives
The most important part of sprinting is the start. To practice the correct starting form:
Stand in front of a wall in a two-point stance, as shown in the following video.
Drive into the wall, achieving triple extension (hip extension, knee extension, ankle plantar flexion) on your back leg, and drive your front knee forward and up to hip height. Your front knee should be bent at 90 degrees in the top position.
Once you're comfortable getting into this position, add more steps to the drill. Mimic this movement when running sprints to ensure a powerful start.
Use this as a warm-up before sprinting to learn proper mechanics. Don't just lean into the wall. Try to drive the wall away from you as hard as you can.
Perform Heavy Sled Drags
Another way to practice efficient acceleration at the start is to perform Heavy Sled Drags for 10 to 15 yards. To be considered "heavy," the weight on the sled should be close to your max Squat. The key here, as with Wall Drives, is to achieve triple extension on the back leg while powerfully driving your front knee forward. Then drive your front foot down and back into the ground to propel yourself forward instead of reaching out and "pulling" yourself forward.
Perform 3-5 sets of 10 to 15 yards with 3 minutes of rest between sets.
Develop Isometric and Eccentric Hamstring Strength
The best way to train your hamstrings to improve running speed is to perform eccentric and isometric exercises. When running, the hamstrings don't act primarily as knee flexors. Instead, they work to keep the knee joint stable as force transfers from the hips. They also assist the glutes in hip extension and slow down knee extension during the swing phase.
For isometric strength, do Bent-Knee Hip Thrusts on a ball or bench for three sets of 10 to 15 reps. Start with your knees at a 10- to 20-degree bend and maintain that angle throughout the entire exercise by contracting your hamstrings. Don't rest your butt on the ground. Just tap and go. Add weight in the form of a barbell or dumbbell placed across your waist if necessary.
For eccentric strength, do Glute/Ham Raises for 3 sets of 8 to 10 reps. Use your arms as little as possible and lower yourself to the ground as slowly as possible.
Use Good Arm Swing Mechanics
An easy way to speed up your sprint is to make sure your arms are moving efficiently. As you run, keep your elbows at 90 degrees and bring each hand up in front of your face. Lower your hand as if you're about to put it in your pocket. Don't let yourself hunch forward with slouched shoulders; it will slow you down.
The Rev-Up Start is a good drill to ingrain good arm swing mechanics. Get into a two-point stance and move your arms as if you were running. Keep your shoulders back and your arms at 90 degrees. After a few practice arm swings, take off into a sprint and maintain focus on your arm swing.
Improve Stride Length
Many runners make the mistake of taking lots of short, choppy steps when they try to run fast. A better option is to take longer strides, and make them as powerful as possible. To lengthen your stride, focus on getting full triple extension on your back leg, rather than attempting to reach forward with your front leg. If your foot lands in front of your center of gravity during acceleration, it will slow you down; so focus on driving your feet back at ground strike instead of just letting your feet smack the ground.
To develop a feel for powerful hip extension, perform three to five sets of Standing Triple Jumps at the beginning of your workout.