Six sprints of 30 seconds each change the blood more than an hour and a half of gentle cycling. A team led by Luke Olsen of Rockefeller University in New York reports this in the journal Cell Reports Medicine.
The researchers asked ten young, active men to ride a bicycle at their absolute limit six times for 30 seconds. Four minutes of rest separated each sprint. Nine further volunteers cycled for 90 minutes at moderate intensity. The scientists measured plasma proteins before the session, immediately afterwards and three hours later.
The gap was stark. Right after the sprints, 714 proteins had changed, almost a quarter of all those detected. In the moderate comparison group the figure was under a quarter of one percent, the science magazine Nautilus reports. Among the proteins released were ones involved in blood-vessel growth, tissue remodelling and hormonal signalling.
Many of them reached the blood by an unusual route. The cell did not secrete them. It clipped them off its own membrane instead, a process specialists call ectodomain shedding. It shortens the path into the circulation.
What the signals set off inside cells
To test the effect, the researchers exposed human muscle and fat cells to the volunteers' plasma. The cells then turned numerous genes up or down. The changes touched energy metabolism, the response to hormones and the sensing of nutrients.
The team then compared its results with health data from more than 53,000 people in the UK Biobank. That dataset links 33 protein markers to a lower risk of obesity, type 2 diabetes and other metabolic disorders. The sprints altered 32 of them.
"What's exciting here is that just a few minutes of intense exercise can trigger a significant molecular response," study author Paul Cohen said in a statement. "And we still see it after eight weeks of training, which tells us this response isn't simply a product of the body struggling to keep up with unfamiliar stress."
The evidence has limits. Both groups held fewer than 20 people and consisted mostly of men. Whether the molecular signals translate into measurable health gains has not been shown. The biobank data offer only an indirect hint.