(7-25-2014) High intensity interval training, also known as HIIT is increasing in popularity because of its’ effectiveness in increasing endurance. It has also been consistantly shown that it is more effective in helping weight loss and stimulating fat metabolism than endurance training at one steady state intensity. Most interval training protocols used in those studies were quite high in intensity, but did take a fair amount of time to complete. To see if a shorter high intensity interval training can be effective as well, scientists of the Universities of West and Central Florida performed the following study which investigates which is better: interval training vs endurance training.

What did the researchers do?

The researchers recruted six healthy young men that exercised regularly in their free time. Before the training sessions every subject was tested on oxygen consumption during rest. Each subject was required to perform three different sessions on stationary bicycle. The first of which was to familiarize them with the equipment and testing protocol. The other two training sessions were a 30 minute continuous endurance training at 60% of heart rate reserve, and the other was an high intensity interval training. The interval training consisted of three sprints at maximum effort of 30 seconds. Between the sprints the subjecs were allowed 4 minutes of active recovery for a total training time of 11 minutes. This protocol is also known as the Wingate Protocol. To minimize the influence of the previous training, sesssions were seperated by at least 48 hours without other strenuous physical activity. During recovery after each training session, oxygen consumption was monitored for 30 minutes.

What were the results?

The results of the study are depicted in the figure below.

Figure 1: Excess post-exercise oxygen consumption (EPOC) during the 30 minute recovery period.

The results indicate that HIIT increases EPOC at all times compared with normal rest during the 30 minute recovery period. Regular moderate intensity endurance training requires only 6 minutes of increased oxygen consumption to recover. EPOC after HIIT was significantly higher compared with Endurance training at all times.

What did the researchers conclude?

The extra oxygen that was needed after training to recover indicates an increased metabolism and therfore increased caloric needs. This is an important factor in weight loss and therefore the reason why interval training is an effective method to lose fat. The researchers concluded that despite a time investment of only 11 minutes, of which only 1,5 minute total training time, HIIT is more effective for weight loss.

What does this mean for me?

-Interval training using the Wingate Protocol is a very effective method to increase metabolism and help weight and fat loss. Although regular endurance training works as well, these effects are far less impressive, especially considering the amount of time it needs for equal results.

-The Wingate Protocol used in this study consisted of three 30 second all out sprints. Between those sprints were four minute periods of active recovery at low intensity. This training form is not suitable for everybody, especially not for people with heart problems.

See also: 

-How to lose weight and fat effectively

Reference:

-Townsend, J.R.,  Stout, J.R., Morton, A.B., et al. Excess Post-Exercise Oxygen Consumption (EPOC) Following Multiple Effort Sprint And Moderate Aerobic Exercise. Kinesiology 2013, 45, 1, 16-21.