The extensive molecular changes that occur during and after working out underscore how consequential activity is for our bodies and health.

When we exercise, the levels of thousands of substances in our bloodstream rise and drop, according to an eye-opening new study of the immediate, interior impacts of working out. The study is the most comprehensive cataloging to date of the molecular changes that occur during and after exercise and underscores how consequential activity — and inactivity — may be for our bodies and health.

Already, of course, we have reams of evidence that exercise alters our metabolisms, muscles, genes, immune responses, hearts, stamina and almost every other organ and biological system within us. But only in recent years, with the development of sophisticated new techniques for counting and typing the thousands upon thousands of different molecules within us, have scientists been able to quantify more of the substances and steps involved in those processes.

With these techniques, they have zeroed in on various sets of molecules in our bloodstreams associated with different aspects of our biology. This research generally is known as “omics” science. Metabolomics, for instance, enumerates and analyzes molecules in our blood that influence metabolism — everything from appetite hormones to enzymes excreted by gut microbes. Genomics maps the molecules involved in gene expression; proteomics ditto for proteins; lipidomics for fat-related molecules; and so on.

Recently, many studies have looked into particular ’omics affected by exercise. Almost all have focused on one arena, such as metabolomics or genomics and usually exclusively in people who are healthy and fit or those who are not.

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.

This undertaking is daunting, but these researchers already had been quantifying the various ’omics of a group of about 100 adult men and women and knew a great deal about their health and fitness. Now, they chose 36 of them, representing an age range between 40 and 75 and a full spectrum of fitness and metabolic health. Some were in good aerobic condition, others out of shape, and some displayed fine blood-sugar control, while others were insulin resistant.

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. Later, they also drew blood from some of the volunteers before and after they had quietly rested, as a control measure.

Then they started counting and characterizing a boggling quantity of molecules in each person’s blood. 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.

They wound up measuring the levels of 17,662 different molecules. Of these, 9,815 — or more than half — changed after exercise, compared to their levels before the workout. Some increased. Others declined. Some gushed immediately after the exercise, then fell away, while others lingered in heightened or lowered amounts for an hour after the workout.

source: The New York Times, link