When it comes to experiments using samples to find out the effect of a variable on an entire population by finding out the representative effect on the sample, the larger the size of the sample, the better.
A larger sample comes closer to being the actual size of the population so when this larger sample is experimented upon, the results it gives will be closer to the results that would be gotten if we experimented on the entire population. The 100 player sprinting experiment would therefore come closer to matching its theoretical probability.