But for the new study, which was published in May in Cell, scientists at Stanford University and other institutions decided to try to complete a full census of almost every molecule that changes when we work out.

The researchers drew blood from each volunteer and then asked them to complete a standard treadmill endurance test, running at an increasing intensity until exhaustion, usually after about nine or 10 minutes of exercise.

The researchers drew more blood immediately after this exertion and again 15, 30 and 60 minutes later.

They looked for molecules that were known to change when people exercise, but also for any that might not have been examined in previous exercise studies but were showing up in people’s blood now.

Some gushed immediately after the exercise, then fell away, while others lingered in heightened or lowered amounts for an hour after the workout.