Dive starts

The dive start is a critical component of swimming performance. This is especially true for the shorter distances where the start has been estimated to contribute up to 30% of the total race in the 50m sprints. A small improvement in starting performance can potentially lead to substantial improvements in the event placing. Therefore we must take this part of our race preparation seriously, and never just stand up and take it for granted.

In current international competition, the grab and the track starts are the most commonly used starting techniques.

Grab start

In this position, the swimmer's centre of gravity is placed as far forward as possible. This results in only a small forward displacement of the CG being required for the body to effectively generate forward propulsion. The arms provide stability and support for maintaining balance. On the starting signal, the hands pull downward and let go of the block.

Track start

The track start simulates the sprint running start which requires an initial rear leg drive, followed by a front leg drive. Upon mounting the starting block, the swimmer places one foot near the back of the block, while the other is positioned so that the toes are curled around the front edge. The front leg provides greater contribution of the total propulsive force and, hence, should be the dominant leg of the swimmer. On the 'take your mark' command, swimmer grasps the front edge of the block with CG well balanced towards the front edge of the block. On the starting signal the swimmer initially pulls on the block with the arms as well as driving forward with the rear foot. Once the CG passes over the front edge of the block, the front leg dominates force production.

As a swimmer pushes off the blocks, force is generated and applied against the starting block. According to Newton's 3rd law, there is an equal and opposite reaction force applied back to the swimmer that is used to generate velocity at take-off. Downwards force application into the blocks will accelerate the body in vertical direction (increased height) and directly backwards to generate propulsion in the forward direction.

In summary:

• There does not appear to be a superior block starting technique, with the grab, track both comprising of a level of trade-off between the time spent on the blocks and the velocity generated.
• Increasing the amount of dive start practice significantly increases dive start performances.
• When entering the water we want to limit the imaginary hole to the smallest diameter we can make. The entire body should pass through the hole to enhance the speed generated from the block. An optimal projection angle will vary slightly between people and has not been quantified for the dive start.
• For those swimmers with a large asymmetry in terms of force production in the grab start (one leg produces significantly more force than the other), it may be worthwhile changing to a track start with the dominant force producing leg forward.
• For swimmers who are very explosive and symmetrical in their force production, it may be worthwhile changing to a grab start where they can produce very high force levels in a short period of time.
• Streamlining is essential at entry and throughout the glide phase where the velocity the swimmer experiences will be the highest of the race. Deviating from a streamlined position will result in a dramatic reduction in speed.
• An efficient dive entry and appropriate timing for underwater kicking and stroke resumption is also required to maximize the starting performance.

Finally some psychology;

When standing behind the block before the race, try and focus on a positive experience (not necessarily related to swimming) that gives you a surge in adrenalin. Practice definitely helps with this tool. When you feel this tingling, step forwards in to an imaginary golden circle and wait for the starters signal.

Happy starts

Jonathon Preston, Assistant Chief Coach