Primarily, a swim start involved swinging the arms in a backward circle before leaving the block (Nicholson, 1999). This start was named the swing start. After this, the grab start was developed. Wilson and Marino (1999) found that in comparison to the swing start, the grab start allowed a swimmer’s take off to be significantly faster, due to the pulling action of the arms, an increase in angular acceleration as a result of the tucked body position, and the absence of the arm swing, which in turn – along with the more forward positioning of the centre of mass – allowed horizontal displacement to begin sooner. This is an important factor, as there was no significant difference in the horizontal velocity between the two dives, but the grab start achieved this velocity in a shorter time. Wilson and Marino’s (1999) findings contradict the findings of Zatsiosky et al in 1979 (Pearson et al, 1998). Their study found the duration of the take off to be less for the swing start than for that of the grab start.
Pearson et al (1998) cited that the grab start is faster at achieving a distance of 4-10m when compared to the swing start. The swing start has a higher angle of body lean at take off than the grab start, due to the effect of the upward arm swing just prior to take off (Wilson and Marino, 1983). This as well as the swing start’s more parabolic flight path in comparison to the grab start’s flatter one, and steeper angle of entry resulted in the swing start achieving a shorter flight distance than the grab start. (Wilson and Marino, 1983) Nicholson (1999) found a significant positive correlation between flight distance and flight time, and therefore it can be assumed that the flight time will also be shorter for the swing start.
A variation of the grab technique known as the ‘hole’ entry (Nicholson, 1999) or ‘whip’ entry (Wilson and Marino, 1983) was developed, which allowed the swimmer’s body to enter the water through the same ‘hole’ made by the hands, therefore reducing resistance (Wilson and Marino; 1983, Pearson; 1998). This technique was characterised by a higher angle of body lean at take off, a more parabolic flight path and a steeper angle of entry to facilitate the ‘hole’ entry, in comparison to the grab start (Wilson and Marino, 1983). Wilson and Marino (1983) found that due to the decrease in resistance, the swimmer was able to conserve horizontal velocity gained at take off whilst under water.
The Wilson and Marino study (1983) concluded that any form of start that involved the hands holding on to the block – that is the grab start and the whip start – resulted in a significantly faster movement time, compared to the swing start. This was said to occur as a result of gaining horizontal velocity faster, via the forward positioning of the centre of mass at the set position, and the pulling down action of the arms on the block.
When comparing the movement time of the grab and whip start, the whip start was found to be significantly faster than the grab start (Wilson and Marino, 1983). This was due to the fact that although there was no significant difference in the position of the centre of mass at the set position, at take off the bodies of the swimmers using the whip start did not fall as far forward, and had a higher angle of body lean.
The handle start came about with the modification of the starting block to include handles at the side of the block. This allows a starting position which has a centre of mass out over the block. Holding on to the handles allows this to occur, without the swimmer overbalancing and falling into the water (Nicholson, 1999). Pearson et al (1998) found as a result of the centre of mass being even further forward than for the grab start, time on the block was significantly shorter than for the handle start. Velocity of the hip was not significantly different for the grab and handle starts, nor was the time taken to reach 7m, the flight time and the glide time.
Since the development of the track start – which also involves the hands holding on to the block – there has been much analysis and comparison with the grab start. Many studies have analysed many different aspects of both dives. Fitzgerald (1973) – cited in Nicholson 1999 – stated that the lowered centre of gravity and the forward position of the body weight in the grab start allowed the swimmer to leave the block more quickly. This was considered to be the main advantage of the grab start over the track start.
Contrary to these results, Ayalon et al (1999) – cited in Nicholson 1999- stated that the track start resulted in leaving the block faster. Mills (2004) stated that the swimmers body position in the track start allows them to uncoil easier and provides a quicker start. The widened position of the feet provides a base of support which is more stable than that of the grab start. The backward positioning of the centre of mass also contributes to this. This stance also contributes to a greater total force being generated from the two independent sources (each leg on the block) as opposed to the one force produced in the grab start. (Ohtsuki;1983, Secher et al; 1988, in Welcher et al; 1999 – in Nicholson 1999)
Ayalon et al (1975) also found that there was a lower body position during flight for the track start (Nicholson, 1999). This has been supported by Mills (2004), who stated that the grab start allowed a steeper angle at take off.
Nicholson (1999) found that there were no significant differences between the two dives for the time to 10 metres, the reaction time, the movement time, the time on the block, flight time or flight distance. He did however find a significant difference in the position of the centre of mass between the track and grab start. For the track start, the centre of mass was more backward, and it continued to move backwards with training.
What Nicholson did find is that strong correlations between different aspects of the dive existed. There was a significant negative correlation between the flight time and the position of the centre of mass in the set position. The more forward the centre of mass, the shorter the flight distance was. A more forward centre of mass was also correlated with faster movement and block times after training. Movement and block times both showed a significant positive correlation with the time to 10m for both dives pre-training. Therefore a faster movement time (and therefore block time) were associated with a slower time to 10m. As previously mentioned, a significant positive correlation was found between flight time and flight distance. Therefore, the more time a swimmer spent in the air, the further they will travel before entering the water. For the grab start, a significant negative correlation between the reaction time and time to 10m was found.
A review of swimming biomechanics by Hay (1986) suggested that there needed to be a shift in studies from focusing on the starting position and movement time in the air, to reducing the resistance that occurs upon entering the water and during the glide.
Hay (1986) also suggested that many of the studies conducted in comparing diving starts have failed to overcome the influence practice has, or the complexity involved in each dive. He found that the least complex and/or the most practiced dives yielded the best results.
