Sprint Interval Training Works, and Here's How To Do It
And as always, the devil's in the details.
Sprint interval training (SIT) has exploded in popularity a decade or two ago, touted as a time-efficient shortcut to aerobic and anaerobic gains without the monotonous hours typically required in traditional endurance training. It has since given up its heralded place to the very long, slow aerobic work we rallied against back then. We are a fickle bunch. So what does the science say now-ish?
This systematic review and meta-analysis by Hall and colleagues examined 55 studies and 432 performance outcomes to determine whether the hype surrounding SIT is backed by solid science—and what protocols actually deliver results. Published in the Journal of Strength and Conditioning Research in 2023, the findings reveal both the promise and the pitfalls of interval training, including critical methodological flaws that may have inflated the reported benefits.
The Study
Sprint interval training involves short bursts of “all-out” effort performed above maximal oxygen consumption, typically on a cycle ergometer, with periods of rest or low-intensity recovery in between. Unlike high-intensity interval training (HIIT), which operates at near-maximal intensities, SIT demands maximal power output during brief efforts lasting anywhere from 6 to 30 seconds. This study aimed to synthesise the existing research on SIT’s effects on physical performance and identify which training variables—such as sprint duration, number of sprints, and recovery time—produce the best outcomes.
Key Points
55 studies were included in the review, comprising 589 subjects who participated in SIT interventions.
Most studies (58%) involved interventions lasting 4 weeks or fewer, with 31% lasting just 2 weeks.
The overall methodological quality was moderate to low: 50% of studies received a moderate quality rating, while 42% received a low rating.
Only 9 studies demonstrated sufficient statistical power, and only 3 adjusted for analysing multiple outcome variables.
Less than half of the studies (44%) reported session attendance, and fewer (39%) included familiarisation sessions for the training protocol.
Extensive small study effects were identified, suggesting that published results likely overestimate SIT’s true effectiveness.
Book a call with me here.
We’ll sit down and upgrade or build out your entire training and performance program in one session.
Aim
The primary aim of this systematic review and meta-analysis was to comprehensively synthesise published research on SIT performed on a cycle ergometer and quantify its effects on physical performance outcomes in healthy adults. The researchers also sought to identify potential moderators, such as sprint duration, volume, intensity, and work-to-rest ratios, that influence training adaptations, and to assess the overall methodological quality of the existing research base.
Methods
Search Strategy
The researchers conducted a comprehensive search of MEDLINE, Web of Science, and SPORTDiscuss databases for studies published between 2000 and February 2020. Studies were included if they involved healthy adults aged 18 to 45 years, featured at least 2 weeks of maximal-intensity sprints on a stationary bike lasting 30 seconds or less, and measured performance outcomes categorised as aerobic, anaerobic, or mixed aerobic-anaerobic.
Inclusion Criteria
Studies were excluded if they recruited overweight or obese subjects, combined SIT with other training modalities (such as resistance training), or involved nutritional supplementation. Both controlled and uncontrolled study designs were accepted.
Quality Assessment
Methodological quality was evaluated using a modified version of the Downs and Black Checklist, which assessed reporting quality, internal validity, confounding factors, and statistical power. Studies were rated as high, moderate, low, or very low quality.
Statistical Analysis
The researchers used Bayesian meta-analysis to calculate standardised mean differences (SMDs) for performance outcomes. They employed three-level random-effects models to account for multiple outcomes reported within the same study and conducted meta-regressions to investigate how training variables (intervention duration, sprint length, number of sprints, and work-to-rest ratios) moderated effects. Small study effects (publication bias) were assessed using funnel plots and Egger’s regression.
