The effects of sprint interval training on aerobic fitness in untrained individuals: a systematic review

Greater aerobic fitness is associated with improved cardiovascular health. Traditionally high volume (long duration and low intensity) endurance training (ET) has been used to increase aerobic fitness. Interval training where periods of hard exercise are interspersed with periods of recovery can also enhance endurance performance. Sprint interval training (SIT) is a low volume and high intensity form of interval training. Energy for SIT is produced via both the aerobic and anaerobic metabolic pathways and is potentially an efficient and effective means to improve aerobic fitness. The aim was to systematically review the effects of SIT on aerobic endurance performance in untrained individuals. PubMed, the Cochrane Library, ScienceDirect, and SPORTDiscus were searched up to August 2008. The reference lists of relevant papers were also searched. Included articles were limited to English language, controlled studies, investigating SIT in healthy untrained or recreationally active participants (VO2max< 55 ml/kg/min) with an outcome measure of endurance performance (as a measure of aerobic fitness). Studies fulfilling the selection criteria were assessed for methodological quality and relevant outcome data extracted. A consistent association was noted between SIT and improved endurance performance. SIT produced an improvement of ∼ 4% (95%CI −0.2 to 8.7), ∼8 to 10% (0.4 to 16), and ∼15% (0.8 to 29) after 1, 2 and 6 weeks respectively. These improvements were of the same magnitude as the improvements noted for ET, but the training volume required was approximately 90% less. Short duration SIT is an effective and efficient form of improving aerobic fitness in untrained individuals. These results could have a significant impact upon physical activity recommendations for health and fitness if further studies can confirm the health benefits associated with longer duration ET also occur with brief SIT interventions.