Saturday, January 21, 2012

How to quantify training load

Quantification of training load is important for several reasons. Firstly, to control periodization, if periodization is possible in football. Secondly, to control the ideal training load needed to achieve training adaptations while avoiding overreaching and overtraining.

The most common methods used to quantify training load in football are shown below. A summary of advantages and disadvantages associated with each of them ia also presented in the table for your consideration.

Table. Methods to quantify training load.
Short description
Time at heart rate zones
Time at certain heart rate (HR) zones based on individual’s maximum heart rate and treadmill testing
Easy data collection and analysis
Relatively high cost for a team system.
HR does not always represent the true physiological load (i.e. in sprint, change of direction)

Blood lactate concentration
Determination of blood lactate concentration
Easy to conduct
Not many players can be evaluated at the same time
Concentration varies and depends on the activity few minutes before sample collection

Rate of perceived exertion (RPE) after training
Perceived exertion is recorded usually 30min post training

Easy & fast
Subjective rating
Motion analysis
Total distance covered, distance at high intensity, recovery time etc are reported using GPS

External work can be estimated more precisely
Internal work is not estimated unless GPS is combined with heart rate recording & RPE
Post-training physiological measurements
Biochemical (CPK), hormonal, physiological (balance between the sympathetic and the parasympathetic nervous system function) and psychological indices are evaluated and recorded some hours after training
Methods are more accurate
A more holistic approach
High cost
Experienced sport scientist is needed
An integrated approached is needed 
More scientific evidence is needed to justify practical use of this approach

Take home message
  • There is a variety of methods to quantify training load. All have advantages and disadvantages. One must decide which is the most appropriate for the situation and remain consistent with data collection and analysis.
  • To my view view a more holistic & integrated approach might help. This approach takes into consideration as many systems of human body function as possible.
For more reading
-Algroy et al. (2011). Quantifying training intensity distribution in a group of Norwegian soccer players. Int J Sports Physiology & Performance, 6(1): 70-81.

-Reilly (2005). An ergonomics model of the soccer training process. J Sports Sci, 23 (6): 561-572.

Monday, January 16, 2012

What is the single best thing we can do for our health?

Dr. Mike Evans, an Associate Professor of Family Medicine and Public Health at the University of Toronto, answers this question in a different way. His video was uploaded on December 2nd, 2011 and more than 1,330,000 people have downloaded it so far. Hope you like it.

Wednesday, January 11, 2012

How much science is enough?

This is a question I have frequently had in my mind. Initially, as a philosophical issue when I was a young student at Loughborough University, UK. Later, as a professional dilemma working with high-level football players. So, it’s a good opportunity to put my thoughts on the paper and summarize my experiences all these years.

Scientific "revolution" in football
Early studies by Christiensen and Hansen in 1939 and by Bergstrom and colleagues in the late 60s were the first to show that carbohydrates and in particular muscle glycogen lowering was the limiting factor to performance in long lasting events such as football. The physiological responses to intermittent exercise, as in football, were firstly described by two research groups from Sweden (Edwards and colleagues in 1973 and Essen, 1978) whereas the first study on the physiological aspects of football playing was published in the early 60s. The “scientific revolution” on football took place after 1975 with research work from outstanding groups by T Reilly, B Ekblom and others. Since that time the number of studies on football has been rapidly increased from 933 in the period 1980-1990 to 1786 in 1981-90 and 4612 in 2001-10! This increasing trend in the number of scientific papers on football paralleled the growth of football market.

Does science impact football performance?
In the English Premier League, most top level clubs have a sport science department and the majority of staff holds a Master’s or a PhD degree. Moreover, a number of fitness coaches are sport scientists as well. Other teams in Europe also have established a sport science department staffed with qualified sport scientists.

Is this enough?
Having a sport science department in the club is not enough. It is the first step but not enough! The key point is the collaboration between the sport science department and coaches and between the sport science, medical and other departments. IT IS THE OSMOSIS BETWEEN THE SPORT SCIENTISTS AND THE COACHING STAFF THAT MAKES THE DIFFERENCE. In my experience, the key things are trust, mindset and good communication.
  • TRUST is being built up day by day, month by month. Usually coaches and sport scientists meet first time in the club. They might even come from different educational and ethnic backgrounds. Normally, they need time to trust each other.
  • MINDSET is also important. Coaches and sport scientists should share the same mindset, should “run or play at the same speed”.
  • COMMUNICATION means that coaches and sport scientists should develop a common communication code. Coaches should be more open to science. Sport scientists, on the other hand, should try to communicate with coaches in a clear and effective way. Some key points for the sport scientists are:
    • CONCENTRATE ON THE IMPORTANT. From a package of numbers, sport scientists should be able to separate the important ones. This requires talent, knowledge and experience.
    • THINK AS A SCIENTIST, ACT AS A COACH. Our role is to evaluate the situation based on scientific evidence. Following that, we must think on the practical applications in the field.
    • RECEIVE FEEDBACK AND IMPROVE. Input from colleagues and other staff members should be filtered and improve thinking and every day practice.
    • STAY OPEN TO THE IMPOSSIBLE. You might have evaluated almost everything but still know a little. We must be open-minded to treat the unexpected. I remember once working with a high level, 1st squad player who got hamstring injuries quite often without any reason as judged from the conventional screening. After extensive testing, we found that player’s red blood cells presented a diminished ability to load adequate oxygen at high exercise intensities. This phenomenon is called arterial hypoxemia and resulted in working muscles hypoxia (lower than normal O2). After partially correcting this limitation with specific training, muscle injuries incidence was substantially reduced. This is also an example on how science works to assist every day practice in high level football.

New challenges in football
One of the roles of sport scientists in a club is to advance sport science knowledge for the benefits of the team. The search of excellence and innovation in various areas (materials, training methods, recovery/regeneration methods etc) will give an advantage to the team. Even a small margin of improvement multiplied by 11 will give a big advantage.

Sport scientists should follow and learn from the advances in other areas like molecular biology, physiology and other markets like NBA, Formula 1, etc. Based on current trends, I believe that new areas which might give advantage in the near future are, among others:
  • Individually prescribed training based on players physiological characteristics and genes. This is an interesting area that has to add in designing more effective training sessions. Indeed, research shows that with similar training program some athletes improve more than others and this is also attributed to the genes.
  • Methods to improve recovery and regeneration. This is also an important area of research in modern football. In particular, fast recovery/regeneration after a match or training is a key element in modern elite level football where players play 2 matches per week.
  • New approaches in talent identification. For instance, recent research from the USA army reported that certain proteins can help in the identification of pilots that perform extremely well under psychological stress and this might have applications to football.
  • Innovations in training methods like the optimal combination of concurrent power and endurance training to maximize training effect, etc.

To achieve excellence we must push the limits beyond the current level. We must always search for innovative approaches to maximize the potential of our players and the benefits of training. To do so, we must be consisted in our approach, focused and clear-minded. I believe that this is the way to maximize the benefits of sport science in improving every day practice in the field.

George Nassis holds a Master’s and a PhD degree in sport science and exercise physiology. He is the Head of PANATHINAIKOS F.C. Performance Laboratory and a Lecturer in Applied Sport and Exercise Physiology at the National and Kapodistrian University of Athens, Greece. He has published a number of scientific papers and has worked extensively with football players. He is an ex Loughborough University student with long experience in Champions League team.

Saturday, January 7, 2012

Do small-sided games improve repeated-sprint ability?

English Premier League official site (January 7th, 2012)
Repeated-sprint ability (RSA) is defined as the players ability to perform maximal or near maximal short-duration sprints (<10 sec) interspersed with short recovery periods (less than 60 sec).  Studies using traditional generic (running) training show an improvement in RSA ranging between 1.5 and 9% after 4-10 weeks in team sport athletes. This large variation in performance gains could be due to differences in training, such as sprint distance, interval time and number of repetitions.

Regarding the effect of training with small-sided games on RSA, it seems that little information is available in the literature. In the study of Hill-Haas and colleagues (2009) young football players trained with small-sided games or running drills for 7 weeks. Small-sided games training consisted of 2-6 repetitions of 6-13 min games separated by 1-3 min of rest.

To summarize their results:
  1. RSA was similarly improved with the two training methods.
  2. This improvement was not significant compared with the pre-training values.
  3. Yo-Yo performance was improved with both training modes. This is important since Yo-Yo test result is associated with football-specific performance.

Take home messages
  1. We know little on the effect of small-sided games in RSA in football players. Questions to be answered are: what is the optimal combination of field dimension, number of players, drill duration, recovery time and number of repetitions?
  2. Small-sided games may be an alternative to generic training for RSA improvement.
  3. Could the combination of small-sided games with generic RS training be more effective?

For further reading
Bishop et al (2011). Repeated sprint ability-Part II. Recommendations for training. Sports Medicine 41(9):741-756.
Hill-Haas et al (2009). Generic versus small-sided games training in soccer. International Journal of Sports Medicine 30:636-642.

Sunday, January 1, 2012

Blog audience statistics

Happy New Year! I hope 2012 is a healthy, happy and productive year for all of you.

It has been 8 months since the start of the blog. For me, it has been a very nice experience so far. Thank you all for your comments and suggestions. I really appreciate your contribution.

Blog audience (May 1st, 2011 to December 31st, 2011)