Tips/Settings for Sharp 10k Start Line Photos

Hi everyone! I volunteer to photograph and take pictures for my local road runners club for various races. Every year they have a 10k road race. This year, today (I just got back) I specifically volunteered to photograph the start line of the race this year.

Runners bunched up, so it was hard to avoid getting some shots that were blurry. I really want to avoid this next year. Any advice on how to avoid blurry runners.

• Gear: Canon 6D Mark II + 24-105mm & 70-200mm lens
• Goal: Crisp runners, in-focus