Jens Bangsbo ia a Danish published author on physiology and sport science. He is also a former assistant coach to both Juventus FC and the Danish national football team.

Jens Bangsbo: Fitness Training in Soccer: A Scientific Approach
Jens Bangsbo: Aerobic and Anaerobic Training in Soccer

Jens Bangsbo is one of the most respected names in sports science. In this series of video’s Jens demonstrates a number of drills and practices that can be used to improve the aerobic and anaerobic conditioning of soccer players. Traditionally soccer conditioning was carried out by performing running exercises. However, small sided games offer several potential benefits:

The players improve their tactical and technical skills.
Other physical elements are trained. For instance, small sided games produce many accelerations and decelerations. These are high stress actions that occur in real matches and if players have not been sufficiently exposed to this type of work in training there is an elevated risk of injury.
The work is intermittent in small sided games by which we mean they combine periods of moderate intensity with periods of very high intensity. The ability to handle abrupt changes in aerobic demands may be better trained in small sided games than in isolated running exercises.

When Jens talks about moderate intensity aerobic exercise he is referring to intensities around 75-85% of maximum heart rate(MHR). While for high intensity aerobic exercise he is referring to intensities between 85-95%of maximum heart rate. A general rule for calculating maximum heart rate is 220 – your age. Jens differs from many when performing high intensity aerobic training in that he prefers shorter intervals. Most academic research has been performed using work intervals in the 3 – 6 minute range. The recovery period is usually half of the work period. However, Jens prefers short intervals, many times around 2 minutes. His reasoning is that the intensity of work is higher in these very short intervals and that this translates into a better quality of play and can produce superior fitness effects because the higher intensity produces more adaptations in the muscle (which has to be able to utilize oxygen pumped to it) even though average heart rates might be slightly lower throughout the exercise (as it takes a while for heart rates to get up into the desired range).

Recovery between the drills is important and the recovery times should be respected. If the work to recovery is too high in this type of work then in the latter repetitions the players will be exhausted and the intensity and quality of play will be much lower than desired. Recovery between repetitions should be active. Research suggest that If the players are able to keep their heart rate around 70% of maximum heart rate in the recovery then this leads to the optimal removal of waste products from the muscle, which in turn leads to better quality in later repetitions.

This type of training is very intense and the total work period does not need to be high. A standard prescription is 4 x 4 minutes work with 2 to 3 minutes recovery and this should be very effective. How effective? Helgerud et al ( Helgerud J, Engen LC, Wisløff U, et al. Aerobic endurance training improves soccer performance. Med Sci Sports Exerc 2001 Nov ) demonstrated that one single session as described above increases a players VO2 max (basically their aerobic capacity) by about 0.5%. Similar results have been repeated in multiple other studies. Repeated over the course of a season this will obviously have a profound effect on aerobic fitness.

High intensity aerobic training could be used twice a week for post pubescent players playing one game per week although the sessions should not be on concurrent days.

Recommended resources:

1/ Dave Tenney Fitness in Football
a great review of where we stand in terms of research and our knowledge about how to condition the modern soccer player

2/ Javier Mallo Periodization Fitness Training

3/ Jens Bangsbo Fitness Training In Soccer: A Scientific Approach

4/ Jens Bangsbo Aerobic and Anaerobic Training Of Players in Soccer: Special Emphasis on Youth Players

5/ Tony Strudwick: Soccer Science