It is clearly totally unexpected that a train will begin to move once the doors have closed. For this reason, there is no reason to hold on to anything.

Instead, you should perform one of two acrobatic routines when the train starts to move:

1) The ‘off-balance tap dancing shuffle’ along the train gangway.

Or

2) The ‘nearly lost my balance but managed to grab a support bar whilst punching the person next to me in the face’ manoeuvre.

You should aim to kick or tread on at least one person’s foot along the way.