"So have you run one of these before?"

Life Watching the start of the half marathon today from my high up vantage point, I noticed that people were carrying around small white plastic tied up bags bulging with something. On my way around the park to get the Sunday newspapers, as I dodging athletes who were running on the pathway instead of the road (I literally turned a corner and there they all were coming towards me) I realised these were civilian clothes for the people taking part, being carried by their relatives and friends. I was curious that some bulged more than others and wondered if something could be understood about the person depending on how much they had in there -- rather like holiday luggage what can be said about someone who doesn't have as much of their lifestyle with them as others. I also worried about the people who didn't have anyone with them supporting. Who was holding onto their bags?