Just three minutes of intense exercise could burn more fat than 90 minutes of moderate cycling, study suggests
Exercising in intense 30-second bursts can deliver more health benefits than 90 minutes of moderate exertion, research suggests.
Adults are currently advised to do at least 150 minutes of moderate-to-vigorous activity each week – the equivalent of two and a half hours of running or cycling.
But researchers in the US now say a short, intense burst of exercise could be a better way to reduce the risk of a range of health issues – including heart disease and diabetes.
‘What’s exciting here is that just a few minutes of intense exercise can trigger a significant molecular response,’ said the study’s lead author, Dr Paul Cohen.
‘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.
‘It may be that the responses we observed are intrinsic to intense exercise.’
The research team, based at Rockefeller University in New York, say the findings show that a quick bout of exercise, easily slotted into busy lives, could make a big difference if done frequently enough.
The study – published in the journal Cell Reports Medicine – compared the health benefits of exercising at varying levels of intensity.
A few minutes of intense exertion could have a bigger impact than 90 minutes of moderate exercise
Doing six 30-second all-out sprints on an exercise bike – resting for four minutes between each – had the most beneficial effect on the body, they found.
Totalling up to just three minutes of intense exercise, done over a half-hour period, the routine triggered rapid changes in 714 blood proteins linked to health and disease.
Proteins in the blood are responsible for transporting vital nutrients and hormones around the body, as well as keeping fluid inside blood vessels and fighting infections.
Intense exercise can impact these proteins by placing extreme demands on muscles – including the heart – forcing them to communicate rapidly with the rest of the body.
In response, cells around the body release a wave of signaling molecules into the bloodstream that help regulate energy consumption and tissue repair.
In comparison to sprint cycling, moderate cycling altered just seven proteins.
The team also compared the effects of two hours of moderate-paced treadmill running and found that, while this altered more proteins than cycling alone, it was still less effective than sprint cycling.
Sprint cycling also caused an immediate surge in proteins responsible for blood-vessel function, tissue repair and hormone signaling.
These short bursts of intense exercise were found to boost levels of Lac-Phe – an exercise-induced molecule that has previously been linked to appetite suppression.
The researchers also found that blood collected after sprint cycling showed signs of major changes in human fat cells – affecting how they burn energy, respond to hormones and detect nutrients.
In lab tests, blood taken after sprint cycling switched on or off more than 1,600 genes in human fat cells, compared with just 25 after moderate exercise.
When the researchers compared these protein levels with health data from more than 53,000 people from the UK biobank, they found that many of these proteins were associated with a lower risk of heart disease.
The connection was particularly striking for obesity and type 2 diabetes – metabolic disorders that affect how efficiently the body produces and uses energy.
Experts believe this may be because short bursts of intense exercise force the body to switch quickly between fuel sources, boosting the mechanisms involved in blood sugar control and fat metabolism.
Of 33 proteins associated with a lower risk of these conditions, 32 were altered by sprinting, compared with just three by moderate exercise.
More than a quarter of these proteins were also linked with slower biological ageing.
The researchers said the findings may help explain why high intensity interval exercises, despite requiring only a fraction of the time of traditional endurance exercise, have repeatedly been shown to deliver powerful health benefits.
‘It’s well appreciated that different intensities of exercise stimulate distinct body-wide adaptations,’ Luke Olsen, an expert in cell biology, and study co-author, said.
‘However, the molecular mechanism linking these intensity-dependent adaptations have remained largely elusive.
‘Our work suggests that exerkines-proteins and metabolites released into the bloodstream following exercise are highly sensitive to exercise intensity and may be the key mediators of the health-promoting effects of short bursts of vigorous exercise.’
However, they acknowledge that more work is needed to determine whether the findings apply more broadly across different age groups and women.
More than 20 million adults in the UK currently fail to meet government guidelines for physical activity.
Around 12 million Britons are considered severely inactive – getting less than 30 minutes of exercise per week.
