My physio suggests I put on a second layer at around the 20 mile mark to reduce heat loss in the closing stages, which he believes leads to reduced performance. Quite the opposite of what everybody else, including myself, does. He refers to the many runners verging on hyperthermia at the finish, wearing tin foil blankets. He suggests a light long-sleeved top which can either be carried to that point, or preferably, have an appointed person at the stage of the race to hand it to you. Not sure I take this, any thoughts?