Another more recent interval training method follows the research of Gunnarsson and Bangsbo published in 2012, called the 10-20-30 Training Concept, more commonly known as the Copenhagen Method (Gunnarsson & Bangsbo, 2012).
In this study, 18 moderately trained runners (6 females and 12 males) were divided into a high-intensity training (10-20-30) group and a control group to compare the effects of both methods on the health profile, muscular adaptations, VO2max, and running performance of the study participants.
While the control group continued their normal training methods during the seven-week study, the 10-20-30 group implemented a format of 30 seconds of low-intensity running at less than 30% of maximal intensity, 20 seconds of moderate-intensity running at less than 60% of maximal intensity, and 10 seconds of high-intensity running at more than 90% of maximal intensity (i.e., a 60-second exercise interval). This interval was repeated five times (i.e., 5 minutes of continuous exercise) before taking a 2 minute recovery, and the entire circuit was repeated three to four times.
At the conclusion of the study, VO2max in the 10-20-30 group was 4% higher, and performance in a 1,500 metre and a 5 km run improved by 21 and 48 seconds, respectively. Furthermore, in the 10-20-30 group, systolic blood pressure was lower by 5 mm Hg, and total and LDL cholesterol were lower by 0.5 and 0.4 mmol/L, (19.3 and 15.5 mg/dL) respectively, in comparison with the control group.
The results demonstrated that this method of training, with short, near-maximal bouts (e.g., 10 seconds), can improve health, fitness, and performance despite large reductions in training volume. This format of training with slightly longer recovery intervals is generally better suited for most individuals contemplating HIIT.
You can find further information on interval training here.
Gunnarsson, T.P. & Bangsbo, J. (2012) The 10-20-30 Training Concept Improves Performance and Health Profile in Moderately Trained Runners. Journal of Applied Physiology. 113, pp.16-24.