Soccer: Alactic-Aerobic Sport: Part II

In part two of this article, Dave discusses the specific adaptations that occur in response to different types of training and the research behind energy systems in repeated sprints. To conclude this discussion, he also finishes up by going over the practical implications of the research and how he approaches training the Seattle Sounders FC as a result of his findings..

What Adaptations Take Place?

Much has been written about the advantages of interval training vs. LSD training, but there has been little discussion about which adaptations actually take place from different types of training.

It’s typically understood that short periods of high-intensity interval training (HIIT) have positive affects on performance, with the benefits of such work slowly reaching a plateau at the 4-6 week mark. Why would this happen? Recent research at the biochemical and even molecular level gives us an insight into what may be taking place in the working musculature in response to such work.

One such recent study (Little et al., 2010) observed the difference in a group of athletes following 6-sessions and two weeks of low-volume, high-intensity training sessions. The sessions consisted of a series of 60-second all out efforts, followed by 75-seconds of low-intensity recovery work.

Typically, “anaerobic” adaptations such as increased glycogen storage and improved buffering ability resulted after two weeks of interval training. Most impressively, molecular pathways similar to endurance training had been triggered, leading to an increase in mitochondrial biogenesis.

In a study of repeated sprint ability (RSA) of professional Italian soccer players as compared to amateur players, Rampini et al. (2009) tried to discern the physiological characteristics associated with a high ability to repeat intermittent sprinting. Their study consisted of 6x40m (shuttle of 20m+20m) with 20 seconds of passive rest in between each repetition.

The results indicated that there were two main factors responsible for a high level of performance in an RSA test. First, and fairly expectantly, the ability to buffer H+ ions was a good indicator of efficiency in intermittent activity. Surprisingly though, the other main indicator was a faster VO2 kinetics indicating that an ability to respond oxidatively during intense intermittent activity is an important adaptation required for high level soccer performance.

In fact, this research found that there was no significant difference between the measured VO2max of the professional and amateur soccer players (58.5 ml/min/kg vs. 56.3 ml/min/kg, respectively), but there was however, a large significant difference in the VO2 kinetics in professional players. It was concluded that the faster VO2 kinetics and improved ability to buffer H+ are vital for an improved RSA, an important characteristics of elite level soccer players. All of this suggests that the desired training adaptations over time may be a lower contribution from anaerobic metabolism due to a faster activation of the aerobic system, as well as a better buffering capacity when glycolysis was utilized.

Anecdotally, we have seen similar results with our MLS team here. Using our OmegaWave technology, we have found that players with an extremely high anaerobic potential are able to create large amounts of energy during matches but often appear to fatigue faster and typically display higher levels of long-term fatigue in the days following competition.

Could it be that such high reliance on anaerobic metabolism will decrease RSA, thus increasing fatigue and time needed in recovery? Rampini et al. suggest that soccer players should prioritize training aimed at improving VO2 kinetics by creating high-intensity (6-10 seconds) work periods, followed by brief recovery periods (20-40 seconds). Most importantly, it seems as though reducing the role of anaerobic energy production in this work is an important indicator in improved RSA performance, since there was little correlation found between lactate and H+ production and RSA ability.

A final review (Iaia & Bangsbo, 2010) by two of the more known soccer-specific researchers Marcello Iaia (Manchester United) and Jens Bangsbo (ex-Juventus, Danish National team) found very similar results across the width of studies they analyzed regarding “speed endurance” (anaerobic) training. Some of the research they cited throughout their review had the following points:

* Repeated 30-sec maximal sprints will show an increased reliance on oxidative phosphorylation, and a decreased utilization of PCr hydrolysis and glycolysis (Parolin et al., 1999).
* Highly trained individuals will experience less of a training effect through the use of low-volume, high-intensity interval work than lesser trained subjects, thus indicating once again that a low-volume interval type of conditioning work may not be the most efficient long-term in maximizing conditioning benefits of elite athletes (Laursen et al., 2002).
* The main immediate training effects of high-intensity interval training appear to be a reduced mean net rate of glycogen degradation (Iaia et al., 2009), and an elevated rate of fat oxidation (Bangsbo et al., 2009).
* There appears to be higher levels of CK flux and activity from 6-sec maximal runs, with 1-min of recovery than when performing a series of 30-sec intense, but submaximal interval runs (Mohr et al., 2007). This again appears to lend credence to the idea of an alactic-aerobic type of fitness work in producing a training response rather than less maximal interval type of work.

Practical Training Application

Alactic-aerobic training has become one of the foundations of what we do through the off-season, as well as in-season with players who do not get a lot of minutes in league play. With only a nine-week off-season training program, we divide our off-season work into three three-week blocks.

As we begin this nine-week off-season period we will often have our athletes perform a three-week general endurance block. We actually see a degradation of the aerobic system over the course of an MLS season, due to travel, lack of high-intensity training time, and residual fatigue. As a result, the first block of training during this off-season period must address general endurance. We will start by stressing either cardiac output or local muscular oxidative ability depending on whether or not that player requires cardiac output work.

After this first block of general endurance our MLS players are ready for some higher intensity alactic-aerobic work. We will start with sets of 8-10 reps of 8-10sec prowler pushes with 40sec rest in between. As we progress through this block we will increase the duration of work slightly – up to around 12sec – while eventually decreasing rest to 30sec.

In our final block of training, then we will use more soccer-specific types of activities for this alactic-aerobic work. We will use more multi-directional sprint activities on our turfed area, or go out to do some sprints up a medium grade hill. The progression from sled work to hill sprints to multi-directional field sprints seems to have produced adaptations in our team that has resulted in athletes this year experiencing increased aerobic, as well as 10sec alactic jump mat test results.

Once the team gets into the in-season portion of work then much of the alactic-aerobic conditioning sessions will be used as “game replacement” exercises for those players who are not playing MLS games. I will typically have a group of 10 players who don’t suit up on MLS game days. I am able to create different high-intensity intensive endurance activities in the form of 5v5 and 4v4+2 soccer-specific training exercises.

However, I will supplement this one-hour training session with three sets of 10 reps of alactic-aerobic fitness work, which will often involve a lateral plyo activity into a 20-25m shuttle (total duration of 8-10sec). The rest can be altered anywhere from 25-40sec between sprints depending on how much of a loading week it is, or what stage of the season.

After the 10 reps are completed we will give the group three minutes of rest before starting the next soccer-specific aerobic activity. In this way, we hope to simulate some the demands of the “repeat-sprint” capacity that is loaded during competition.

Final Thoughts

What is our “take home” message from the review of all of this research? Soccer is a sport that stresses and utilizes each one of the energy systems at different rates and different times during elite match play. The question for the S&C/fitness coach is which energy systems should be stressed, and in what manner, during the training process in order to maximize adaptations and on-field performance.

It appears pretty clear from the evidence laid out in the research cited in this article that the aerobic-oxidative system is the key system which will determine metabolic performance potential. While the ability to be fast and powerful will rely on the PCr (alactic) system during those very important bursts of movement required, it’s the aerobic system which will help replenish those PCr stores as quickly as possible.

Where does the anaerobic-glycolytic system fit in? There will be times when the body WILL need to use glycolysis in order to continue intense movement. PCr stores may be exhausted, or an athlete’s VO2 kinetics may be too slow to provide oxidative energy soon enough. In this moment, glycolysis IS important.

However, it’s very important that an athlete does not become too reliant on glycolysis for energy, as the byproducts of glycolysis – H+, lactate, lowered pH – will both slow PCr replenishment, as well as eventually inhibiting further glycolysis from taking place.

In these moments, it’s pretty clear that soccer should strive to be an alactic-aerobic sport as much as possible, yet still have a developed enough anaerobic-glycolytic system that it can sustain high levels of energy with little byproduct production as possible.

References

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