Last 30 days

Saturday, October 29, 2011

The science of happiness

by Harvard psychologist Professor Dan Gilbert on TED
http://www.ted.com/talks/dan_gilbert_asks_why_are_we_happy.html

Chronic co-ingestion of L-carnitine and carbohydrate improves performance


Carnitine is a molecule involved in fatty acid translocation in the mitochondria (Figure 2 below). Theoretically, increased carnitine levels within the muscle would increase fatty acid metabolism thus sparing muscle glycogen. Glycogen sparing will improve endurance performance. However, research over the past 30 year was unsuccessful in elevating muscle carnitine levels with oral carnitine ingestion.





What’s new?
Few months ago a research group from the University of Nottingham Medical School, UK, showed elevated muscle carnitine levels after chronic carnitine ingestion in healthy subjects (Wall et al., 2011). Subjects were divided into two groups: a) the carnitine group, ingested 80g of carbohydrate (CHO) containing 2 gr of L-carnitine tartrate for 5,5 months, and b) the control group that received only CHO for the same period. Supplements were ingested at breakfast and 4 hours later. Physiological measurements and performance test took place before and at the end of the supplementation period.


The main findings were
  • 21% increase in muscle carnitine level with oral ingestion
  • lower muscle glycogen utilization during submaximal exercise in the carnitine group
  • 35% improvement in the performance test in the carnitine group (Performance was defined as total work output in 30-min cycling in the laboratory).


Although this is a laboratory study, the findings suggest that chronic co-ingestion of L-carnitine and carbohydrate may improve endurance performance. This is the first study to show increased muscle carnitine levels with oral supplementation. To my opinion, these findings have important implications for athletic performance.

Reference

Wall et al (2011). Chronic oral ingestion of L-carnitine and carbohydrate increases muscle carnitine content and alters muscle fuel metabolism during exercise in humans. Journal of Physiology 589: 963-973.

Monday, October 24, 2011

Post-training muscle cooling may attenuate training effects

Today, I would like to comment more on a point I made few weeks ago in a post on cryotherapy after training (http://georgenassis.blogspot.com/2011/07/some-thoughts-on-use-of-water-immersion.html). Please let me remind you that cryotherapy is used by many athletes as a means to minimize muscle damage and muscle soreness and thus speed up recovery after hard training and game. In my latest post I set the hypothesis that cryotherapy-induced reduction in muscle damage and inflammation might suppress training adaptations.


One of the blog reader emailed  me the paper by Yamane et al (1996) published in European Journal of Applied Physiology. In their study, researchers had their subjects cool one leg and arm with water immersion after training whereas the other limb was the control (no cooling). One group performed arm strength training and the other endurance cycling training. Training was performed 3-4 times per week for 4-6 weeks.




Did cryotherapy improve performance more that the control?
No. In this study, control and cooled legs improved endurance performance time at similar degree. However, maximal oxygen uptake was improved only in the control leg. In addition, maximal arm strength was improved at a significantly greater magnitude in the control than in the cooled arms group.

Take-home message
I am not saying that cryotherapy is not good for recovery. There are a lot of data in the literature suggesting that cryotherapy might speed up, at least, the perception of effort by athletes. If you feel good you perform well in the next session. If you perform well you gain more adaptations. However, from this study it appears that the effect of cryotherapy on LONG-TERM training-induced adaptations requires further investigation.



Reference
Yamane et al. (2006). Post-exercise leg and forearm flexor muscle cooling in humans attenuates endurance and resistance training effects on muscle performance and on circulatory adaptations. Eur J Appl Physiol 96: 572-580.

Wednesday, October 19, 2011

Carbohydrate ingestion in training and game: why is needed?


A large amount of research suggests carbohydrate (CHO) ingestion either in liquid or solid form prior to and during prolonged exercise that lasts more than 1 hour. Limited information exists regarding the role of this strategy on performance in intermittent exercise such as football. From these studies, it appears that carbohydrate ingestion before and during exercise improves intermittent endurance capacity. Although there are no scientific data, I speculate that total distance covered and distance covered at moderate/high intensity should be improved with carbohydrate ingestion. From published research, it seems that sprint performance remains unaffected by CHO ingestion.


It is noteworthy that football skills seem to be affected by CHO ingestion. Ajmol Ali and Clyde Williams from the University of Loughborough asked 17 players to perform a football-specific intermittent test and also evaluated skill performance under two experimental conditions: 1) following ingestion of a CHO-electrolyte solution before and every 15min during the test, 2) following ingestion of a placebo solution of equivalent taste and volume. Their results showed a 17% reduction in skill performance during the control trial. This reduction was only 3% in the CHO trial. Thus, it seems that carbohydrate ingestion during exercise may maintain football skill performance during the game.

What is the mechanism behind performance improvement?
Football skill maintenance with carbohydrate ingestion could be due to direct effect of CHO in the central nervous system. Indeed, recent studies show that CHO when in the mouth may activate brain regions that are involved in reward and motor control (Chambers et al., 2009). There are two more explanations for the positive effect of CHO ingestion on intermittent running performance:  a) the sparing of muscle glycogen, b) the maintenance of blood glucose, although hypoglycemia is not usually presented in running.



Table. Effect of carbohydrate ingestion prior and during exercise that simulates football on performance.

Sprint
Endurance capacity
Skills
Decision-making
Effect
No effect
Positive
Positive
Positive
Level of evidence
5
5
3
3
Level of evidence ranges from 1 (very low) to 5 (very strong)



Is it safe for youth players?
Yes, it is. There is no study to suggest that youth players should not ingest carbohydrate solutions. Recent studies show that carbohydrate ingestion either in a beverage or gel improves intermittent endurance capacity in young players (Phillips et al., 2011a; Phillips et al., 2011b).

What to drink, how much and at what time?
-You can drink carbohydrate solutions before (150-250ml for 80kg body weight) and during exercise (at regular intervals when it is possible). Players should try to consume 50-60 g CHO per hour.
-It is better to drink solutions than contain 2-7% CHO or 20-70 gr CHO per liter.
-Commercially available carbohydrate drinks contain electrolytes. Electrolytes a) improve the drink’s taste, b) speed glucose entry into the bloodstream.
-Recent studies suggest that adding some protein may improve more endurance capacity compared with the CHO-electrolyte solution (Alghannam, 2011).
-Choose the drink temperature you like. Drink temperature must be mild and not too low (<5oC)
-It is not easy for the players to ingest beverages or solid CHO before a game or at half-time. EXPERIMENT YOUR STRATEGY BEFORE USING IT IN THE GAME.
-Do not overdo it. If you drink too much you might get stomach discomfort.


For additional reading
Ali and Williams (2009). Carbohydrate ingestion and soccer skill performance during prolonged intermittent exercise. J Sports Sci 27(14):1499-1508.

Alghannam (2011). Carbohydrate-protein ingestion improves subsequent running capacity towards the end of a football-specific intermittent exercise. Appl Physiol Nutr Metab 36(5):748-57.

Chambers et al. (2009). Carbohydrate sensing in the human mouth: effects on exercise performance and brain activity. J Physiol 587:1779-94.

Nassis et al (1998). Effect of a carbohydrate-electrolyte drink on endurance capacity during prolonged intermittent high intensity running. Br J Sports Med 32(3):248-252.

Phillips et al. (2011). Carbohydrate ingestion during team games exercise: current knowledge and areas for future investigation. Sports Med 41(7):559-585.


Sunday, October 16, 2011

Speed, agility, quickness (SAQ) training method: what’s new?

Performance in football depends among others on the ability to react fast, take fast steps, be quick in the first 5 m, and make fast movements in changing directions. All this happens in an unpredictable way for a period of at least 90min. Thus football players need to undertake strength, power, balance, speed, agility and endurance training. This makes conditioning planning a complex process.

Today, I would like to comment only on the speed, agility, quickness training. This is the so called SAQ training method. Unfortunately, there are no many scientific studies on SAQ method in elite football players. One of them is that recently published by Jovanovic and colleagues (2011). In this study, high level junior players were divided into two groups: the control group that did regular training Monday to Friday and one game each Saturday and the experimental group. Players in this group supplemented their regular training with 3 SAQ training sessions a week (Monday, Wednesday and Thursday morning for 90-120min each).





After 8 weeks of SAQ training, players showed

  • 2,1% improvement in 5m time (Quickness)
  • 3,7% improvement in 10m run (acceleration) 
  • 1% improvement in counter-movement jump (power)
No improvement in these fitness parameters were seen in the control group.


Conclusions
1)     SAQ training is effective in improving fitness in high-level players.
2)     To improve these factors coaches should plan SAQ training at least 3 times per week for 90-120 min each session.
3)     The improvement with SAQ training seems to be due to adaptations taking place in the central nervous system and the muscle itself.

Wednesday, October 12, 2011

A soccer-specific neuromuscular training program to reduce injuries in young players

In a study published last year by Emery and Meeuwisse (2010) from the University of Calgary, Canada, the effect of a soccer-specific neuromuscular training on injury rate was examined in 13-18 years old players. 750 players were split in two groups: the neuromuscular training group and the control group. Players in the first group supplemented their regular training with a neuromuscular training program performed before training. Players in the control group did only regular training. The program was for 20 weeks.

Neuromuscular training included:
-15min warm up
-10min of neuromuscular training with body weight
-15min of balance training using a wobble board

Some of the exercises are presented in figures 1-4 below (pictures are from Emery and Meeuwisse, 2010, Br J Sport Med).






Main findings
-Injury rate was almost half in the neuromuscular training group compared with the control group. In particular, the overall injury rate in the neuromuscular training group was 2.08 injuries/1000 player-hours and 3.35 injuries/1000 player-hours in the control group.

-Rates of ankle and knee sprains were lower in the neuromuscular training group compared with the control group.

CONCLUSION AND PRACTICAL APPLICATIONS
It seems that this neuromuscular training program reduces the risk of ankle and knee sprain injuries in youth players.

Cristiano Ronaldo tested for skills

Monday, October 10, 2011

Cristiano Ronaldo tested for mental ability

Be at the right place at the right moment to make the right action


So far, I have written a lot on the physiological aspects of modern football. Today I would like to deal with some key tactical aspects and support my words with scientific evidence.

At the elite level, it seems that differences between players during the game are more related to tactics, motivation and specific technical skills. Tactical skills refer to the quality of the player to adopt the right action at the right moment.


 












Is there scientific evidence behind it?
In a study published last year, researchers from the University of Groningen, The Netherlands, evaluated tactical skills in 105 elite youth players who participated in the their club’s talent development program at the start of the project (around 16-18 years of age) and at adulthood (21 years or older). At the adulthood, players were grouped as amateurs (2nd national division or lower) and professionals (those playing either with a premier league club or on the first team of the 1st division of the national league). Tactical skills were assessed with a specific questionnaire. Among others the scales “Positioning” and “Deciding” were evaluated.

Their results showed that those player scoring “good” to “excellent” in the “Positioning” and “Deciding”  at the age of 16-18 years were almost 7 times more likely to reach the professional level that those scoring in the lowest categories.

It seems that besides physical fitness, the ability to be at the right place at the right moment to make the right action is a key factor that differentiates between professional and amateur players.


Practical applications
We could add subscales “Positioning” and “Deciding” to our talent identification program.

Sunday, October 9, 2011

Cristiano Ronaldo: what makes a top performer?


Cristiano Ronaldo is not only a fantastic player but a top athlete as well. He presents the right mixture of football skills with football-specific athletic performance.


The series of videos that will be posted show some of the performance tests of Cristiano Ronaldo.

Video 1 is on speed and agility testing.

Saturday, October 8, 2011

How to estimate maturity in young players

Power, strength and endurance are all important aspects of physical fitness in top level football. In pre-pubertal boys these parameters are affected not from chronological but biological age. This explains the large variation in performance between pre-pubertal boys of similar chronological age.

Indeed, biological age is associated with hormonal changes that affect performance. For instance, puberty in males is associated with elevated testosterone concentration. High testosterone levels in the blood stream will increase muscle and heart size and this will result in sprint, jump and endurance improvements. Thus, the estimation of biological age or maturity level is important to talent identification and development in modern football.

Methods for maturity estimation
-x-ray of the fingers, hand and wrist: A hand is easily x-rayed with minimal radiation and shows many bones in a single view. The bones in the x-ray are compared to the bones of a standard atlas. This is the “gold standard” method that also can be used for height prediction with an acceptable accuracy.

-anthropometry: this is an indirect method based on certain simple anthropometric measures. It is a practical method predicting years from peak height velocity age (maturity offset value).

The equation is
Maturity offset= -9.236 + 0.0002708 (leg length X sitting height) - 0.001663 (age X leg length) + 0.007216 (age X sitting height) + 0.02292 (weight/height)

To read more on skeletal age in football please visit
Nassis G. Do talented players become elite adults? http://www.bmj.com/content/338/bmj.b490/reply


Tuesday, October 4, 2011

How to increase first step speed in football players


Strength and in particular power are important fitness components in modern football. This is because short sprints averaging 2-4 seconds might be decisive of the match result. Looking at the match analysis data, a 2-4 sec sprint occurs every 90 sec. In addition, more than 95% of sprints are shorter than 30 m and almost half of them are shorter than 10 m. It seems therefore that velocity attained in less than 10 m run and even velocity during the first step are very important fitness components.

To maximize these abilities players need to improve power. This can be done with conventional strength training, plyometric exercises and a combination of both. Let me remind you that plyometric exercises involve stretching the muscle immediately before making a rapid concentric contraction. Indeed, some studies have shown an improvement in sprint time and jumping in football players after 7-8 weeks of plyometric training.


In a recent study, Chelly and colleagues (2010) examined if plyometric training would enhance performance in young experienced players. 19 years old players were divided into the experimental and the control group. The experimental group supplemented its regular football training with plyometric exercises, 2 times per week for 8 weeks in-season.

Weekly plyometric training consisted of

-40 to 60-cm hurdle jumps X10 reps X 5-10 sets in the first 4 weeks
-40-cm drop jumpsX10 reps X 5-10 sets in the following 4 weeks

Main findings
-velocity during the first step improved by 18% with plyometric training and only 9% with regular football training

-velocity in the first 5-m of sprint improved by 10% with plyometric training and only 3% with regular training

-Maximum sprinting velocity improved by 9% with plyometric training and only 2,5% with regular training

-vertical jump improved by 2,5 % with plyometric training, no change with regular training

CONCLUSION AND PRACTICAL APPLICATIONS
In-season hurdle and drop jumps performed 2 times a week for 8 weeks can improve first step speed and enhance sprinting  to a greater extent than regular football training in young, experienced players.

Sunday, October 2, 2011

Beta alanine supplementation: does it improve performance?


Fatigue at certain points of the game or training is related, among other factors, to the high concentration of H+ in the muscle which can limit the ability of muscle contraction. Thus, any intervention that can reduce the rate of intracellular H+ accumulation during high intensity exercise would increase performance.

Physiological role of β-alanine
Carnosine is a cytoplasmic dipeptide found in skeletal muscles and in the central nervous system. One of the physiological effects of carnosine is to buffer H+. Muscle carnosine is formed by bonding histidine and beta (β)-alanine and previous studies have shown an increase in muscle carnosine concentration after long term β-alanine supplementation.



Recent findings
In a recent study, Sale et al. (2011) from the Nottingham Trent University, UK, had their subjects perform an anaerobic test before and after 4 weeks of either β-alanine supplementation (6.4 gr/day) or placebo intake. Their results showed a 16% improvement in performance during the anaerobic test that lasted 150 sec. Although this is different to what happens in football we can assume that β-alanine supplementation may enhance anaerobic performance in football players.

To my knowledge there is only one study using a football specific protocol (repeated sprints on the treadmill). In this study, physically active men performed 2 sets of  5x5-sec sprints with 45sec recovery after 5 weeks of β-alanine supplementation (Sweeney et al., 2010). Their results showed no effect of β-alanine supplementation on repeated sprints abillity.

The findings of these studies seem contradictory. To my point of view this is not the case. From these and other studies in the literature it seems that β-alanine supplementation may enhance performance during exercise bouts that stress lactic acid production and lactic acid accumulation. When exercise, as in the case of the study by Sweeney et al. (2010) above, does not result in high lactate and thus H+ accumulation β-alanine has no effect on performance. No doubt that more research, in particular on football players is needed before reach a conclusion.

One more point. There is strong evidence that β-alanine supplementation a) reduces body fat, and b) increases muscle strength. Both effects have applications to football training and performance.


What is the effective strategy?
The effective protocol seems to be the ingestion of 6.4 gr/day β-alanine for 4 weeks. Tablets should be consumed at 4 equal doses at 3 to 4 hours intervals.