I'm going for my pb at a Parkrun this weekend. I like to do some strides and such while the instructions and introductions are being made, and when others are getting to the startline. However, this Parkrun has over 800 participants every weekend, and to get a good position for a sub 20 minute attempt you need to get a good place near the start in plenty of time, like at least 10 minutes. But then it's so packed, that you barely have space to swing your arms.
What's the best way to stay warmed up in those 10 minutes in a confined space, particularly given that it's going to be close to freezing at 9 am? Is it simply running on the spot? Fast high knees (on the spot of course)? Vertical jumps (I see a lot of elite runners like Jakob do this in the minute before the start)?