Recently, a novel type of high-intensity interval training known as sprint interval training has demonstrated increases in aerobic and anaerobic performance with very low time commitment. However, this type of training program is unpractical for general populations. The present study compared the impact of a low-volume high-intensity interval training to a "all-out" sprint interval training. Twenty-four active young males were recruited and randomized into three groups: (G₁: 3-5 cycling bouts ËŸ 30-s all-out with 4 min recovery; G₂: 6- 10 cycling bouts ËŸ 125% P_max with 2 min recovery) and a non-trained control group. They all performed a VO₂max test, a time to exhaustion at P_max (T_max) and a Wingate test before and after the intervention. Capillary blood lactate was taken at rest, 3, and 20 min after the Wingate trial. Training was performed 3 sessions per week for 4 weeks. In G₁, significant improvements (p < 0.05) following training were found in VO₂max (9.6%), power at VO₂max (12.8%), T_max (48.4%), peak power output (10.3%) and mean power output (17.1%). In G₂, significant improvements following training were found in VO₂max (9.7%), power at VO₂max (16.1%), T_max (54.2%), peak power output (7.4%; p < 0.05), but mean power output did not change significantly. Blood lactate recovery (20^th min) significantly decreased in G₁ and G₂ when compared with pre-testing and the CON group (p < 0.05). In conclusion, the results of the current study agree with earlier work demonstrating the effectiveness of 30-s all-out training program to aerobic and anaerobic adaptations. Of substantial interest is that the low volume high intensity training provides similar results but involves only half the intensity with double the repetitions.

• Given the markedly lower training volume in the training groups, our results suggest that intense interval training is indeed a time-efficient strategy to induce rapid metabolic and performance adaptations.

• The results demonstrate that a practical low-volume HIT program is effective for improving metabolic and performance adaptations that resemble many of the same performance gains occurred in all-out SIT protocol.