Sprint interval training (SIT)
Sprint interval training uses short all-out efforts, typically 20–30 s, separated by easy recovery. Meta-analyses show it raises VO2max by about 8%, the same as moderate continuous training, with far less time. Just two or three sprints per session work as well as more.
What the science says
- Raises VO2max as much as endurance training Strong evidence
A meta-analysis of 16 randomized trials (Gist et al., 2014) found SIT raised aerobic capacity by about 3.6 mL/kg/min (about 8%), with no difference from moderate continuous endurance training.
- More sprints per session do not add more Strong evidence
A meta-analysis of 93 trials with 1,188 participants (Hutchinson et al., 2026) found SIT raised VO2max by 8.3%; adding sprints per session made a trivial difference, while longer programs (+0.7% per extra week) mattered more.
- Health gains in a fraction of the time Moderate evidence
In 12 weeks of training in sedentary men (Gillen et al., 2016), 3 × 20 s all-out sprints in a 10-min session improved VO2peak (19%), insulin sensitivity and muscle mitochondrial content as much as 45 min of continuous cycling, with a five-fold lower exercise volume.
How to apply it
Use a bike, warm up, then do a few true all-out sprints with easy pedaling in between.
Who should be careful
All-out sprints are very demanding. If you are sedentary, older, or have heart disease, high blood pressure, diabetes or chest symptoms, get medical clearance first and build up from moderate cardio. Stop if you feel chest pain, dizziness or unusual breathlessness. Cycling sprints are gentler on the joints and hamstrings than running sprints.
Frequently asked questions
Does sprint interval training improve fitness as much as long cardio?
Yes for VO2max: about an 8% gain, with no difference from moderate continuous training in a meta-analysis of 16 trials.
How many sprints do I need per session?
Two to four are enough; a meta-analysis of 93 trials found more sprints per session made a trivial difference.
How much time does it take?
In one 12-week study, sessions lasted 10 min with just 1 min of all-out sprinting, and results matched 45 min of continuous cycling.
Scientific references
- Sprint interval training effects on aerobic capacity: a systematic review and meta-analysis
- Number of Sprint Repetitions in a Sprint Interval Training Session Does Not Moderate Improvements in V̇O(2)max With Training: A Systematic Review and Meta-Analysis
- Twelve Weeks of Sprint Interval Training Improves Indices of Cardiometabolic Health Similar to Traditional Endurance Training despite a Five-Fold Lower Exercise Volume and Time Commitment
More training methods
- Drop sets Moderate evidence
A drop set takes a set to failure, then immediately cuts the load and keeps going.
- Rest-pause sets (including myo-reps) Limited evidence
Rest-pause means taking a set close to failure, resting 15–30 seconds, then squeezing out a few more reps, repeated a few times.
- Supersets Moderate evidence
A superset pairs two exercises back to back with little or no rest.
- High-intensity interval training (HIIT) Strong evidence
HIIT alternates short hard efforts with recovery.
- Zone 2 training Limited evidence
Easy, steady cardio clearly improves fitness and health, but the popular claim that "Zone 2" is a special, optimal intensity for building mitochondria and burning fat is not supported.
- Fasted training (fasted cardio) Limited evidence
Training on an empty stomach burns more fat during the session, but that does not translate into more fat lost over weeks.