Saturday, February 4, 2012

Low-volume high-intensity interval training: what’s new?

From the Official website of Manchester City
A number of studies from Burgomaster and Gibala from McMaster University, Canada, have shown that low-volume high-intensity interval training (HIT) results in muscles’ adaptations and endurance performance improvements that are similar to those induced after the traditional endurance training. For example, in one of the first such studies by Gibala et al (2006) 16 healthy university students were assigned either to HIT or traditional endurance training group (ET). Training for the HIT group consisted of 4-6 repetitions of 30 sec “all-out” supramaximal exercise with 4 min recovery. In the ET group, individuals performed continuous 90-120 min cycling at 65% of their peak maximal oxygen uptake. Training was performed 3 times per week for 2 weeks in both groups. Training time (including rest periods) was 14-23 min for HIT and 90-120 min for ET. Endurance was assessed with time trials on the cycle ergometer and the average performance in this test was ~60min before training.

The results of this study showed that endurance performance was improved at the same degree with both low-volume high-intensity interval and continuous endurance training (Gibala et al., 2006). This effect was despite the fact that exercise volume and training time were much lower in HIT compared to ET (about 90% and 75% lower, respectively).

What’s new?
In a recent study, Jonathan Little and colleagues (2010) from the same research group, introduced a modified HIT realizing that it is hard for the individuals to perform repeated bouts of supramaximal exercise. In their study, they asked again seven men to train 3 times per week for 2 weeks with HIT. Training consisted of 8-12 repetitions of 60sec bouts at 100% of peak power output as it was previously determined on the cycle ergometer. Active cycling at low loads was introduced for 75sec between each sprint.

Their results showed that:
  1. Endurance performance was improved by 9-11% with HIT. This is a big change considering the timeframe it was achieved (over 2 weeks or 6 training sessions).
  2. This improvement was associated with increased skeletal muscle oxidative capacity. This indicates that HIT was effective in altering working muscles’ quality.

Do these changes translate in football match performance improvements?
We don't know. There are no studies to show the effect of this kind of HIT on football endurance. Of course, it is difficult to replicate the above mentioned training protocol in the field. More work is needed to define the most effective and practical protocol for HIT in the field. Iaia et al (2009) have shown that performing repeated sprints at 93% of the speed achieved in a 30sec “all-out” sprint run was effective in maintaining muscle oxidative capacity and endurance performance in well-trained runners.

Another limitation for the majority of above mentioned studies is that they used active and mainly non-trained individuals. So we do not know if these findings apply to highly trained football players. Besides that, one must remember that football is a multi-task sport and success is determined by a mixture of factors such as physical, tactical, technical, psychological and environmental.

General Comments
In my view HIT is a nice tool for endurance performance improvement in football players. However, only players that are used with performing repeated high intensity bouts could train this way effectively. I believe that before you apply this training method as fitness coaches you must consider the followings:
  • INTENSITY: the intensity is maximal and this will increase injury risk. In addition, a sudden change in training intensity may not always be beneficial.
  • DURATION: It seems that this training should incorporate bouts of 30-60 sec. This is a very hard training that stresses also the anaerobic lactic acid mechanism of energy production. Therefore, children and some adolescents should avoid this kind of training.

For more reading
  • Burgomaster et al (2005). Six sessions of sprint interval training increase muscle oxidative potential and cycle endurance capacity in humans. Journal of Applied Physiology 98, 1985-1990.
  • Gibala et al (2006). Short-term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance. Journal of Physiology 575, 901-911.
  • Iaia et al (2009). Four weeks of speed endurance training reduces energy expenditure during exercise and maintains muscle oxidative capacity despite a reduction in training volume. Journal of Applied Physiology 106, 73-80.
  • Little et al (2010). A practical model of low-volume high-intensity interval training induces mitochondrial biogenesis in human skeletal muscle: potential mechanisms. Journal of Physiology 588, 1011-1022.

No comments: