Low-volume high-intensity interval training induces performance and metabolic adaptations that resemble ‘all-out’ sprint interval training

For journal club we looked at the following paper:

Bayati M, Farzad, B, Gharakhanlou R, et al. A practical model of low-volume high-intensity interval training induces performance and metabolic adaptations that resemble ‘all-out’ sprint interval training. Journal of Sports Science and Medicine, 2011; 10:571-76

What was the aim of the paper?

The researchers wanted to compare a sprint interval training (SIT) protocol (3-4 x 30 seconds ‘all out’ effort with 4 minutes recovery) versus a high intensity interval training (HIT) protocol (6-10 x 30 seconds with 125% Pmax with 2 minutes recovery) . They hypothesised that the training induced changes would be the same between the two protocols. The research was carried out by researchers from the Department of Physical Education and Sports Sciences at Tarbiat Modares University.

What did the study involve?

The researchers recruited 24 male graduate students who were habitually active. After a familiarisation trial, the participants carried out a graded exercise test on a cycle ergometer to measure VO2max and power at VO2 max (Pmax). They also did a test to determine the time to exhaustion at Pmax by cycling to fatigue at a self-selected cadence. Finally they carried out a 30 second Wingate test to analyse peak power output (PPO), mean power output (MPO) and total work (Wtot).

The researchers then assigned the participants to one of three groups; HIT, SIT or a control group. The participants trained 3 times a week for 4 weeks. Following the training intervention, the three tests above were repeated. Blood lactate was measured at rest and three and 20 minutes after the Wingate test only.

What were the main results?

The researchers found that following the four week training programme, Pmax, VO2 max and PPO were significantly increased in both training groups compared to the control group. MPO increased significantly with SIT compared with the control group, but MPO did not change significantly with the HIT group. Blood lactate was significantly different in both training groups compared to the control group.

What can we take from it?

I enjoyed reading this study because I am very interested in the research area, especially after watching it on BBC Horizon. It was an easy paper to read and had some good points to take away from it. The researchers clearly stated a research question and hypothesis, and used a simple study design to test the research question. They used a quick and easy training protocol that would be easy for the general population to carry out and because the researchers used participants that were not athletes, it made the results relevant for the general population. The use of a control group in the study helped to eliminate bias and they used a relatively large number of participants compared to similar research (although they did not state if they had used a power calculation for sample size).

Although the paper had many good points, there were a number of areas that I questioned. The training was only carried out over a period of four weeks and I would have liked to see the long-term effects of the training protocols. The study was not a repeated measures design and the researchers matched the subjects, but they did not state the criteria for this and also did not say how they randomised the participants into the groups. I would have liked to have seen how the diet and physical activity adherence was measured. I also wonder why the researchers only measured blood lactate. They could have measured other markers of fitness, such as heart rate and also perceptual measures, including rating of perceived exertion. Finally, this training protocol would not be suitable for people who had an existing medical condition.

The following points that Dan made about the research are very valid.

• Are the two adequately distinctive enough to warrant such investigation? 125% Pmax for obese, unfit and/or unaccustomed individuals is still a big ask and questionably unsustainable for long-term exercise prescription. As well as being difficult to quantify this intensity in real life.
• With regard to adding to current literature, relevant is the finding that lower intensity (125% Pmax vs. ‘all out’) but more repetitions (6-10 vs. 3-5) provide similar metabolic and performance gains.
• Would be interesting if subjects were to see comparable improvements with the comparison of HIT and SIT protocols used in the current study against the utilisation of those rest periods to conduct low intensity recovery exercise (interval training)

Overall, I enjoyed reading this study but would have liked it to be a bit ‘meatier’ and feel like some important points were missing.