Just three minutes of sprinting can produce a very different molecular response than that which occurs after 90 minutes of moderate exercise.
Researchers at Rockefeller University compared how the body responds to exercise performed at different intensities. They found that six 30-second all-out sprints changed almost a quarter of the proteins measured in the blood immediately after exercise. In comparison, 90 minutes of continuous moderate cycling altered less than a quarter of one percent. Moderate treadmill running affected more protein than cycling, but still much less than the short sprint session.
Sprint Triggers Rapid Molecular Rise
Speed training also altered more than 200 metabolites and rapidly increased levels of proteins involved in blood vessel growth, tissue remodeling, and hormonal signaling.
Some of these proteins appeared to reach the bloodstream through a rapid cell signaling process called ectodomain shedding: Instead of being produced and released again, pieces of proteins that were already located on the surface of cells were cut off and quickly sent into the circulation.
The researchers also tested how human fat cells responded to blood drawn after a sprint. Those cells showed widespread changes in gene activity, including changes in the way they processed fuel, reacted to hormones, and sensed nutrient availability.
Moderate exercise produces a slower response
Moderate exercise caused a much less dramatic immediate reaction. A substantial increase in fatty acids and liver-derived proteins associated with the demands of resistance exercise did not appear in the bloodstream until three hours after training.
Human fat cells exposed to blood drawn after a moderate cycle also showed only small changes in gene activity.
Links to metabolic health and biological aging
The researchers then compared the proteins that responded to exercise with health information from more than 53,000 participants in the UK Biobank. Many of these proteins were associated with lower risks of cardiovascular and metabolic diseases.
The pattern was especially notable in obesity, type 2 diabetes and other metabolic disorders. Among the 33 proteins associated with lower risk, 32 were altered by sprinting, while only three were affected by moderate exercise. More than a quarter of those proteins were also linked to slower biological aging.
“The interesting thing here is that just a few minutes of intense exercise can trigger a significant molecular response,” says Cohen. “And we still see it after eight weeks of training, which tells us that this response is not simply a product of the body’s struggle to keep up with an unknown stress. It may be that the responses we see are intrinsic to intense exercise.”
Why exercise intensity may matter
The findings suggest that exercise intensity can strongly influence the proteins and metabolites released into the bloodstream and, in turn, the way tissues throughout the body respond.
“It is well known that different exercise intensities stimulate different adaptations throughout the body,” says Luke Olsen, a postdoctoral fellow who conducted the studies. “However, the molecular mechanisms linking these intensity-dependent adaptations remain largely elusive. Our work suggests that exercins (proteins and metabolites released into the bloodstream after exercise) are highly sensitive to exercise intensity and may be key mediators of the health-promoting effects of short bursts of vigorous exercise.”