In most sports an explosive start is a must. Not only for track athletes but even in field and court sports where accelerating short distances is required.
To have an explosive start the athlete must have great strength in the extensors (hips) quads, knee flexion and extension, glutes and eccentric strength in the hamstrings. The box start will devlop these muscle groups.
When performed properly the box squat can provide greater benefits than a regular style squat.or leg press.
Start with light wqeight to learn technique then increase resitance.
You can perform the squat one of two ways. First, squatting down just to the point of touching the box or secondly, completely sitting on the box before raising up.
*Reps and sets are season dependent.
The technique is best described by this edited excerpt from Louie Simmons at http://www.deepsquatter.com:
Box squats are to be done on a below parallel box (I suggest paralell for beginners).
1. Fill your stomach with air and push out against your belt. Push your knees out to the sides and with a tightly arched back, squat back, not down, until you are sitting on the box (or touching).
2. Sit back as far as possible and push against the bar, not the box, to come up. Remember, the form is butt back, knees out. Work hard on controlling your descent and maintaining you form. As you descend, so shall you rise. Never drop onto the box.
3. Pause on the box (or just to touch). Relax the hip flexors and then contract strongly as you drive back into the bar to stand up (quickly). Don’t turn the feet out too far.
4. Use a flat soled shoe.
Remember, hamstrings and glutes are the key.
5. Generally, you will use weights between 65-82.5% of the 1RM on the box you are using. Most of the time this will be about 50-70% of what you squat.
6. Keep rest periods short – 45-75 seconds.