Saturday, April 19, 2014

Who is leading the change in a Club or Organization?


Look at the best clubs and the best teams in the world, being in sport or other sector. What do they have in common?

Someone might say that it is the players/employees who make the difference in a team or organization. I would agree, at least in part. No change will happen if the CEO or the Board of Directors or the Head Manager, whoever is leading the team/organization, are not ready for the change and are not convinced about the “where to go”.

The leader will develop the vision & the strategic plan, he will communicate it with all people involved and will inspire them to work hard every day for the common purpose.

If (the leader) has a clear vision he will place the right people at the right position. This will be one of the first steps for a successful journey.

Take home message
Next time choose your manager!

For further reading
Jim Collins. Good to Great. Harper Business, 2001

Anita Elberse with Sir Alex Ferguson. Ferguson's formula. Harvard Business Reviews, October 2013 http://hbr.org/2013/10/fergusons-formula/ar/1  

Friday, March 28, 2014

Effect of cryotherapy on performance: what's new?

Open Access J Sports Med. 2014 Mar 10;5:25-36. eCollection 2014.

Whole-body cryotherapy: empirical evidence and theoretical perspectives. Bleakley CM, Bieuzen F, Davison GW, Costello JT.

Abstract
Whole-body cryotherapy (WBC) involves short exposures to air temperatures below -100°C. WBC is increasingly accessible to athletes, and is purported to enhance recovery after exercise and facilitate rehabilitation postinjury. Our objective was to review the efficacy and effectiveness of WBC using empirical evidence from controlled trials. We found ten relevant reports; the majority were based on small numbers of active athletes aged less than 35 years. Although WBC produces a large temperature gradient for tissue cooling, the relatively poor thermal conductivity of air prevents significant subcutaneous and core body cooling. There is weak evidence from controlled studies that WBC enhances antioxidant capacity and parasympathetic reactivation, and alters inflammatory pathways relevant to sports recovery. A series of small randomized studies found WBC offers improvements in subjective recovery and muscle soreness following metabolic or mechanical overload, but little benefit towards functional recovery. There is evidence from one study only that WBC may assist rehabilitation for adhesive capsulitis of the shoulder. There were no adverse events associated with WBC; however, studies did not seem to undertake active surveillance of predefined adverse events. Until further research is available, athletes should remain cognizant that less expensive modes of cryotherapy, such as local ice-pack application or cold-water immersion, offer comparable physiological and clinical effects to WBC.

FULL paper http://www.dovepress.com/whole-body-cryotherapy-empirical-evidence-and-theoretical-perspectives-peer-reviewed-article-OAJSM


Int J Sports Physiol Perform. 2013 May;8(3):227-42. Epub 2013 Feb 20.
Cooling and performance recovery of trained athletes: a meta-analytical review. Poppendieck W, Faude O, Wegmann M, Meyer T.

Abstract
PURPOSE: Cooling after exercise has been investigated as a method to improve recovery during intensive training or competition periods. As many studies have included untrained subjects, the transfer of those results to trained athletes is questionable. METHODS: Therefore, the authors conducted a literature search and located 21 peer-reviewed randomized controlled trials addressing the effects of cooling on performance recovery in trained athletes. RESULTS: For all studies, the effect of cooling on performance was determined and effect sizes (Hedges' g) were calculated. Regarding performance measurement, the largest average effect size was found for sprint performance (2.6%, g = 0.69), while for endurance parameters (2.6%, g = 0.19), jump (3.0%, g = 0.15), and strength (1.8%, g = 0.10), effect sizes were smaller. The effects were most pronounced when performance was evaluated 96 h after exercise (4.3%, g = 1.03). Regarding the exercise used to induce fatigue, effects after endurance training (2.4%, g = 0.35) were larger than after strength-based exercise (2.4%, g = 0.11). Cold-water immersion (2.9%, g = 0.34) and cryogenic chambers (3.8%, g = 0.25) seem to be more beneficial with respect to performance than cooling packs (-1.4%, g= -0.07). For cold-water application, whole-body immersion (5.1%, g = 0.62) was significantly more effective than immersing only the legs or arms (1.1%, g = 0.10). CONCLUSIONS: In summary, the average effects of cooling on recovery of trained athletes were rather small (2.4%, g = 0.28). However, under appropriate conditions (whole-body cooling, recovery from sprint exercise), postexercise cooling seems to have positive effects that are large enough to be relevant for competitive athletes.


J Strength Cond Res. 2014 Mar 11. [Epub ahead of print]
Effect of run training and cold-water immersion on subsequent cycle training quality in high performance triathletes. Rowsell GJ, Reaburn P, Toone R, Smith M, Coutts AJ.

Abstract
The purpose of the study was to investigate the effect of cold-water immersion (CWI) on physiological, psychological, and biochemical markers of recovery and subsequent cycling performance following intensive run training. Seven high-performance male triathletes (age: 28.6±7.1 y; cycling VO2peak: 73.4±10.2 mL·kg·min) completed two trials in a randomized crossover design consisting of 7 x 5-min running intervals at 105% of Individual Anaerobic Threshold followed by either CWI (10°C±0.5°C) or thermoneutral water immersion (TNI; 34±0.5°C). Subjects immersed their legs in water five times for 60-s with 60-s passive rest between each immersion. Nine hours post-immersion, inflammatory and muscle damage markers, and perceived recovery measures were obtained before the subjects completed a 5-min maximal cycling test followed by a high quality cycling interval training set (6 x 5-min intervals). Power output, heart rate (HR), blood lactate (La) and rating of perceived exertion (RPE) were also recorded during the cycling time-trial and interval set. Performance was enhanced (change, ±90% confidence limits) in the CWI condition during the cycling interval training set (power output (W·kg ), 2.1±1.7%, La (mmol·L), 18±18.1%, La:RPE, 19.8±17.5%). However, there was an unclear effect of CWI on 5-min maximal cycling time-trial performance and there was no significant influence on perceptual measures of fatigue/recovery, despite small to moderate effects. The effect of CWI on the biochemical markers was mostly unclear, however there was a substantial effect for interleukin-10 (20±13.4%). These results suggest that compared to TNI, CWI may be effective for enhancing cycling interval training performance following intensive interval running training.


J Sport Rehabil. 2014 Mar 12. [Epub ahead of print]
Comparison of Electrical Stimulation Versus Cold Water Immersion Treatment on Muscle Soreness Following Resistance Exercise. Jajtner AR, Hoffman JR, Gonzalez AM, Worts P, Fragala MS, Stout JR.

Abstract
CONTEXT: Resistance training is a common form of exercise for competitive and recreational athletes. Enhancing recovery from resistance training may potentially improve the muscle remodeling processes, stimulating a faster return to peak performance. OBJECTIVE: To examine the effects of two different recovery modalities, neuromuscular electrical stimulation (NMES), and cold water immersion (CWI) on performance, biochemical and ultrasonographic measures. PARTICIPANTS: Thirty resistance-trained males (23.1±2.9yrs; 175.2±7.1cm; 82.1±8.4kg) were randomly assigned to NMES, CWI or control (CON). DESIGN AND SETTING: All participants completed a high-volume lower-body resistance training workout on day one and returned to the Human Performance Lab 24- (24H) and 48h (48H) post-exercise for follow-up testing. MEASURES: Blood samples were obtained pre-exercise (PRE), immediately post (IP), 30-minutes post (30P), 24H and 48H. Subjects were examined for performance changes in the squat exercise (total repetitions, and average power per repetition), biomarkers of inflammation, and changes in cross sectional area (CSA) and echo intensity (EI) of the rectus femoris (RF) and vastus lateralis (VL) muscles. RESULTS: No differences between groups were observed in the number of repetitions (p=0.250; power: p=0.663). Inferential based analysis indicated that increases in C-reactive protein (CRP), concentrations were likely increased by a greater magnitude following CWI compared to CON, while NMES possibly decreased more than CON from IP to 24H. Increases in IL-10 concentrations between IP-30P were likely greater in CWI than NMES, but not different compared to CON. Inferential based analysis of RF EI indicated a likely decrease for CWI between IP-48H. No other differences between groups were noted in any other muscle architecture measures. CONCLUSIONS: Results indicated that CWI induced greater increases in pro- and anti-inflammatory markers, while decreasing RF EI, suggesting CWI may be effective in enhancing short-term muscle recovery following high-volume bouts of resistance exercise.

Friday, March 14, 2014

Carbohydrate ingestion during exercise: time to rethink its role?

The effect of carbohydrate (CHO) ingestion on performance during prolonged exercise has been investigated in a number of studies. The majority of published papers show a positive effect. Does this fact mean that CHO ingestion during exercise is beneficial to exercise performance under all conditions? Is this effect due to biological advantage? 

Nassif and colleagues from the School of Human Movement Studies, Charles Sturt University, Australia, published a nice study in 2008 that questions the value of CHO ingestion during exercise.

What they did?
Nine well trained athletes with VO2max 65.8 ml/kg/min cycled at 70% of VO2max until volitional fatigue under three experimental conditions while
  • ingesting placebo capsules with distillated water (PLAc),
  • ingesting CHO capsules with distillated water (CHOc),
  • ingesting CHO capsules with distillated water whilst both researchers and athletes knew that CHO were being consumed (CHOk).

What they found?
  • Exercise duration was similar between PLAc and CHOc
  • Exercise duration was 24% longer in CHOk compared with PLAc

Take-home message
  • The ingestion of carbohydrate capsules did not improve performance under these experimental conditions.
  • Knowledge of the ingested ergogenic substance may improve performance. "Coaches and trainers of endurance athletes should be aware that knowledge of the performance enhancement supplement may have a significant psychological effect on endurance performance" (Nassif et al., 2008). 

Source
Nassif et al. Double blind carbohydrate ingestion does not improve exercise duration in warm humid conditions. Journal of Science and Medicine in Sport 2008; 11: 72-79.

Friday, March 7, 2014

Repeated sprint training in hypoxia: a new training method?



scienceopen.com
 The use of methods to speed up adaptations to training are of major importance especially for high level athletes. Along this line, recent studies have investigated the repeated sprint training in hypoxia as a new training method. Raphael Faiss, Olivier Girard and Gregoire Millet from Aspetar and the University of Lausanne have published a relevant review in the December issue of the British Journal of Sports Medicine which is free to download at http://bjsm.bmj.com/content/47/Suppl_1/i45.full.pdf+html

Given the opportunity you can also watch the video of a recent study conducted by Olivier in Aspetar (http://www.youtube.com/watch?v=cl62P771uU4 ).

Hope you enjoy both!

George


How to make millionaires to sweat?

huffingtonpost.com
This is one of the most challenging opportunities in our professional life. Are millionaires willing to sweat and improve themselves? How can we (the sport scientists) influence them to work harder? Here are some tips:

  • Share with them your vision and plans: show them that you are ready to sweat first. If they see the “fire inside” you they will follow.
  • Ask them to set their objectives: Simply, they must write on a piece of paper how they see themselves next year, after 2 years etc. Ask them to write down the objective of each month. The objectives must be SMART (Specific-Measurable-Achievable-Relevant-Time based).
  • Give them feedback: Have they achieved this month’s objective? Why not? What they have to change? Be honest and specific. 
  • Challenge them: Millionaires need new approaches, methods and more challenging targets. Stress yourself to find new ideas. Get out of your comfort zone. Challenge them to get out of their comfort zone!

Saturday, March 1, 2014

Does wearing compression garments improve performance and speed-up recovery?

Del Coso et al. Compression stockings do not improve muscular performance during a half-ironman triathlon race. Eur J Appl Physiol. 2014, 114(3):587-95.

Abstract
PURPOSE: This study aimed at investigating the effectiveness of compression stockings to prevent muscular damage and preserve muscular performance during a half-ironman triathlon.

METHODS: Thirty-six experienced triathletes volunteered for this study. Participants were matched for age, anthropometric data and training status and placed into the experimental group (N = 19; using ankle-to-knee graduated compression stockings) or control group (N = 17; using regular socks). Participants competed in a half-ironman triathlon celebrated at 29 ± 3 °C and 73 ± 8 % of relative humidity. Race time was measured by means of chip timing. Pre- and post-race, maximal height and leg muscle power were measured during a countermovement jump. At the same time, blood myoglobin and creatine kinase concentrations were determined and the triathletes were asked for perceived exertion and muscle soreness using validated scales.

RESULTS: Total race time was not different between groups (315 ± 45 for the control group and 310 ± 32 min for the experimental group; P = 0.46). After the race, jump height (-8.5 ± 3.0 versus -9.2 ± 5.3 %; P = 0.47) and leg muscle power reductions (-13 ± 10 versus -15 ± 10 %; P = 0.72) were similar between groups. Post-race myoglobin and creatine kinase concentrations were not different between groups. Perceived muscle soreness (5.3 ± 2.1 versus 6.0 ± 2.0 arbitrary units; P = 0.42) and the rating of perceived effort (17 ± 2 versus 17 ± 2 arbitrary units; P = 0.58) were not different between groups after the race.

CONCLUSION: Wearing compression stockings did not represent any advantage for maintaining muscle function or reducing blood markers of muscle damage during a triathlon event.



Vercruyssen et al. The influence of wearing compression stockings on performance indicators and physiological responses following a prolonged trail running exercise. Eur J Sport Sci. 2014,14(2):144-50.

Abstract
The objective of this study was to investigate the effects of wearing compression socks (CS) on performance indicators and physiological responses during prolonged trail running. Eleven trained runners completed a 15.6 km trail run at a competition intensity whilst wearing or not wearing CS. Counter movement jump, maximal voluntary contraction and the oxygenation profile of vastus lateralis muscle using near-infrared spectroscopy (NIRS) method were measured before and following exercise. Run time, heart rate (HR), blood lactate concentration and ratings of perceived exertion were evaluated during the CS and non-CS sessions. No significant difference in any dependent variables was observed during the run sessions. Run times were 5681.1±503.5 and 5696.7±530.7 s for the non-CS and CS conditions, respectively. The relative intensity during CS and non-CS runs corresponded to a range of 90.5-91.5% HRmax.

Although NIRS measurements such as muscle oxygen uptake and muscle blood flow significantly increased following exercise (+57.7% and + 42.6%,+59.2% and + 32.4%, respectively for the CS and non-CS sessions, P<0.05), there was no difference between the run conditions.

The findings suggest that competitive runners do not gain any practical or physiological benefits from wearing CS during prolonged off-road running.



Bieuzen et al. Effect of wearing compression stockings on recovery after mild exercise-induced muscle damage. Int J Sports Physiol Perform. 2014, 9(2):256-64. 

Abstract
Background: Compression garments are increasingly popular in long-distance running events where they are used to limit cumulative fatigue and symptoms associated with mild exercise-induced muscle damage (EIMD). However, the effective benefits remain unclear.

Objective: This study examined the effect of wearing compression stockings (CS) on EIMD indicators. Compression was applied during or after simulated trail races performed at competition pace in experienced off-road runners.

Methods: Eleven highly trained male runners participated in 3 simulated trail races (15.6 km: uphill section 6.6 km, average gradient 13%, and downhill section 9.0 km, average gradient -9%) in a randomized crossover trial. The effect of wearing CS while running or during recovery was tested and compared with a control condition (ie, run and recovery without CS; non-CS). Indicators of muscle function, muscle damage (creatine kinase; CK), inflammation (interleukin-6; IL-6), and perceived muscle soreness were recorded at baseline (1 h before warm-up) and 1, 24, and 48 h after the run.

Results: Perceived muscle soreness was likely to be lower when participants wore CS during trail running compared with the control condition (1 h postrun, 82% chance; 24 h postrun, 80% chance). A likely or possibly beneficial effect of wearing CS during running was also found for isometric peak torque at 1 h postrun (70% chance) and 24 h postrun (60% chance) and throughout the recovery period on countermovement jump, compared with non-CS. Possible, trivial, or unclear differences were observed for CK and IL-6 between all conditions.

Conclusion: Wearing CS during simulated trail races mainly affects perceived leg soreness and muscle function. These benefits are visible very shortly after the start of the recovery period.

Source
PubMed 

Saturday, February 22, 2014

Is cold water immersion beneficial or harmful to long-term performance improvement?


 
wikipedia
Cold water immersion (CWI) is a popular means for athletes recovery. Although most of the studies report an improved feeling of fatigue following CWI, not all of them agree on the performance benefits. The aim of this post is to stimulate the discussion on the effect of repeated sessions of cold water immersion on performance and adaptations to training.

As you may remeber I published a post in July 2011 challenging the concept of CWI as a means of recovery in athletes http://georgenassis.blogspot.com/2011/07/some-thoughts-on-use-of-water-immersion.html. The idea was that CWI, which reduces exercise-induced inflammation, may result in attenuated adaptations to training. Let me remind you that exercise-induced inflammation is a "trigger" to adaptations and hence every method that reduces inflammation would affect adaptations to training in a negative way.

The study by Halson et al. (2014) published few days ago in Medicine & Science in Sports and Exercise tested the effect of repeated CWI sessions on performance of trained cyclists. Their results showed that, following 39 days of training, cyclists in the CWI condition did not show performance impairement compared with the control group. This data do not support the speculation that prolonged use of CWI may attenuate adaptations to training. I am sure you will build your own opinion by reading the paper, but there are 2 points I would like to raise; the first point is that CWI did not produce any performance benefit compared with the control condition in this study. So, what's the reason of using CWI besides the players/athletes satisfaction? The second point is that we still don't know what might happen with longer exposure to CWI.

In another study, volunteers had one limb in cold water post training while the other leg was not cooled (Fröhlich et al., 2014). The individuals performed strength training for both legs for a period of 5 weeks. The results of the study showed a tendency for greater strength gains in the control group.

Overall, these recent findings highlight the need for more studies on the effect of repeated CWI sessions on long-term performance. Given that it is difficult to have high performance athletes in these experiments, studies with competitive athletes would help a lot.

For more reading
 Halson SL1, Bartram J, West N, Stephens J, Argus CK, Driller MW, Sargent C, Lastella M, Hopkins WG, Martin DT. Does Hydrotherapy Help or Hinder Adaptation to Training in Competitive Cyclists? Med Sci Sports Exerc. 2014 Feb 5. [Epub ahead of print]

Fröhlic M, Faude O, Klein M, Pieter A, Emrich E, Meyer T. Strength training adaptations after cold water immersion. J Strength Cond Res. 2014 Feb 18. [Epub ahead of print]

http://georgenassis.blogspot.gr/2011/10/post-training-muscle-cooling-may.html

Friday, February 14, 2014

Are there biomarkers to predict adaptations to training?

The variability in exercise training induced adaptations is a fascinating subject both for scientists and practitioners. From a practical point of view many have noticed that some individuals may improve more with training than others. It would be very helpful in the future if we are able to identify the players/athletes with higher potential in advance.

What is the science behind the heterogeneity of adaptations to training? What are the prevailing concepts in the area? The papers below, free to download, might be useful.
George

http://jap.physiology.org/content/110/3/846.full.pdf+html

http://jap.physiology.org/content/108/6/1487.full.pdf+html

Friday, January 24, 2014

How to combat the negative effects of hyperthermia on cognitive function?

Although cognitive performance improves with mild heat strain, an impairements might be observed at high levels of hyperthermia (gastrointestinal temperature above 39 oC, Racinais et al., 2008). Neck cooling has been shown to improve enduarnce performance in previous studies but very limited information exists on the effect of this method on cognitive function.

The study by Lee and colleagues, published this week in the European Journal of Applied Physiology, examined the effect of neck cooling on cognitive performance during prologed exercise in the heat. A neck-cooling collar was placed on the neck of individuals who run for 75min or until exhaustion in an environmental chamber which mantained dry bulb temperature of 30 oC and 70% relative humidity.

The main finding was that neck cooling may enhance performance in high complexity tasks. It is important to note that this beneficial effect was observed while the neck-cooling collar was kept at the neck for the enitre period of exercise. Although this method of cooling could be applied in some endurance events, certain questions need to be answered before using it in team sports. For instance, what is the effect of neck cooling when applied just before the start of the match an/or in half-time?

For further reading
Lee et al. Neck cooling and cognitive performance following exercise-induced hyperthermia. Eur J Appl Physiol 2014;114: 375-384
Racinais et al. Hyperthermia impairs short-term memory and peripheral motor drive transmission. J Physiol 2008;586: 4751-4762

Friday, January 3, 2014

Do muscles "remember"? Implications for training

The term "muscle memory" has been used to describe the observation that muscle function related tasks seem to be performed more effectively after a period of detraining in previously trained muscle groups compared with the control ones. Additional evidence on this phenomenon has been published on October 28th 2013 by Egner, Bruusgaard and colleagues in the Journal of Physiology.


What they did?
  •  Mice were treated with testosterone for 14 days. This treatment resulted in 66% increase in the number of myonuclei and 77% increase in fibre cross-sectional area.
  • Fibre size was decreased within 3 weeks of treatment removal. However, myonuclei number remained elevated for at least 3 months post-treatment. 
  • At the end of the 3 month post-treatment period, exercise that lasted 6 days increased cross-sectional area by 31% in the group with elevated myonuclei without any change in the control group.

Potential practical applications
Based on these findings, the authors speculated that muscles might "remember". It can be assumed that previously trained muscles/individuals might improve at a faster rate when they resume training after a period of detraining compared with the control ones. "Muscle memory" could also explain, at least in part, why some individuals improve more with training than others.

Future challenges
Does strength training early in sports life, which results in extra nuclei, maximize the athletic potential?

Source
Egner, Bruusgaard, Eftestol and Gundersen (2013). A cellular memore mechanism aids overload hypertrophy in muscle long after an episodic exposure to anabolic steroids. Journal of Physiology DOI: 10.1113/physiol.2013.264457

Thursday, December 5, 2013

High intensity exercise for performance enhancement & health promotion (FREE downloads)



Laursen P (2010). Training for intense exercise performance: high-intensity or high-volume training? Scand J Med Sci Sports. 2010, 20 Suppl 2:1-10.

http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0838.2010.01184.x/pdf


Oliveira BR, Slama FA, Deslandes AC, Furtado ES, Santos TM.Continuous and high-intensity interval training: which promotes higher pleasure? PLoS One. 2013 Nov 26;8(11):e79965.

http://www.plosone.org/article/fetchObject.action?uri=info%3Adoi%2F10.1371%2Fjournal.pone.0079965&representation=PDF 

Monday, November 11, 2013

Training loads and injuries (FREE downloads)



Gabbett TJ. Reductions in pre-season training loads reduce training injury rates in rugby league players. Br J Sports Med. 2004 Dec;38(6):743-9.

 http://bjsm.bmj.com/content/38/6/743.long


Johnson A, Doherty PJ, Freemont A. Investigation of growth, development, and factors associated with injury in elite schoolboy footballers: prospective study. BMJ. 2009, 338: b490

http://www.bmj.com/content/338/bmj.b490.pdf%2Bhtml

Saturday, November 9, 2013

What's new on small-sided games?

A number of interesting papers have been published on small-sided games. Without ignoring the importance of each one of them, I would like to focus more on the paper published by Fradua and colleagues in the Journal of Sports Sciences (Fradua et al., 2013).

The aim of the study was to examine, among others, the individual playing area and length and width of the rectangles during professional football (soccer) matches.


Matches from 5 different 1st Spanish division teams were analysed and the main findings were:
  • The individual playing area ranged from 79 to 94 m2.
  • Rectangle length and width varied at different playing zones (1-6; zone 1 was the zone nearest the goal of the team in possession of the ball & zone 6 was the one nearest the opponent's goal).

Practical implications
  • Pitch sizes should vary and range between 80 (zone 3 & 4) and 90 m2 (zones 1, 2, 5 & 6)
  • Length to width ratio should also be adjusted to 1:1 (zones 1, 2, 5 & 6) and 1:1.3 (zone 3 & 4)

Source
Fradua, Zubillaga, Caro, Fernandez-Garcia, Ruiz-Ruiz, Tenga (2013). Designing small-sided games for training practical aspects in soccer: extrapolating pitch sizes from full-size professional matches. J Sports Sci 31(6): 573-581

Thursday, November 7, 2013

What's new in sport science?




Training and game loads and injury risk in elite Australian footballers

Rogalski B, Dawson B, Heasman J, Gabbett T (2013). J Sci Med Sport  16(6): 499-503

Tohe aim was to examine the relationship between combined training and game loads and injury risk in elite Australian footballers. Prospective cohort study. Forty-six elite Australian footballers (mean±SD age of 22.2±2.9 y) from one club were involved in a one-season study. Training and game loads (session-RPE multiplied by duration in min) and injuries were recorded each time an athlete exerted an exercise load. Rolling weekly sums and week-to-week changes in load were then modelled against injury data using a logistic regression model. Odds ratios (OR) were reported against a reference group of the lowest training load range. Larger 1 weekly (>1750AU, OR=2.44–3.38), 2 weekly (>4000AU, OR=4.74) and previous to current week changes in load (>1250AU, OR=2.58) significantly related (p<0.05) to a larger injury risk throughout the in-season phase. Players with 2–3 and 4–6 years of experience had a significantly lower injury risk compared to 7+ years players (OR=0.22, OR=0.28) when the previous to current week change in load was more than 1000AU. No significant relationships were found between all derived load values and injury risk during the pre-season phase. In-season, as the amount of 1–2 weekly load or previous to current week increment in load increases, so does the risk of injury in elite Australian footballers. To reduce the risk of injury, derived training and game load values of weekly loads and previous week-to-week load changes should be individually monitored in elite Australian footballers.


The physiological response, time-motion characteristics and reproducibility of various speed endurance drills in elite youth soccer players: small sided games vs generic running.
 
Ade, Harley, Bradley (2013). Br J Sports Med 47(17): v-e4     
The aim of the study was to quantify the physiological responses, time-motion characteristics and reproducibility of various speed endurance production (SEP) and speed endurance maintenance (SEM) drills. Twenty-one elite male youth soccer players completed four drills: (1) SEP 1 v 1 small sided game, (2) SEP running drill, (3) SEM 2 v 2 small sided game and (4) SEM running drill. The SEP drills consisted of eight bouts of 30 s with 120 s recovery (1:4 exercise to rest ratio) whilst SEM drills encompassed eight bouts of 60 s with 60 s recovery (1:1 exercise to rest ratio). Heart rate response, blood lactate concentration, rating of perceived exertion and time-motion characteristics were recorded for each drill. The SEP and SEM running drills elicited greater (P<0.05) heart rate responses, blood lactate concentrations and subjective ratings of perceived exertion than the equivalent small sided games (ES: 1.1-1.4 & 1.0-3.2). Players covered less (P<0.01) total distance, high-, very high-speed running and sprint distance in the SEP and SEM small sided game's compared to the equivalent running drills (ES: 6.0-22.1 & 3.0-18.4). Greater distances (P<0.01) were covered in high and maximum acceleration/deceleration bands during the SEP and SEM small sided game's compared to the equivalent running drills (ES: 2.6-4.6 and 2.3-4.8). Small-moderate test-retest variability was observed for heart rate response (CV: 0.9-1.9%), ratings of perceived exertion (CV: 2.9-5.7%) and blood lactate concentration (CV: 9.9-14.4%); Moderate-large test-retest variability was observed for high-intensity running parameters (CV: >11.3%) and the majority of acceleration/deceleration distances (CV: >9.8%) for all small sided games and running drills. The data demonstrate the differential response of SEP and SEM training for taxing various energy systems and the superior acceleration/deceleration profiles of small sided games compared to generic running drills.


Effects of small-sided game and change-of-direction training on reactive agility and change-of-direction speed.


Young, Rogers (2013). J Sports Sci Sep 9 [Epub ahead of print]

The purpose of this study was to determine the effects of training change-of-direction speed and small-sided games on performance in the Planned-AFL agility test and reactive agility. Twenty-five elite-standard U-18 Australian Rules football players were randomly allocated either to a change-of-direction group or a small-sided games group. Players participated in one or two 15-min sessions per week with 11 sessions conducted over a 7-week period during the season. Tests conducted immediately before and after the training period included the Planned-AFL agility test and a video-based reactive agility test specific to Australian Rules football. The reactive agility test variables were total time, decision time and movement response time. The small-sided games group improved total time (P = 0.008, effect size = 0.93), which was entirely attributable to a very large reduction in decision time (P < 0.001, effect size = 2.32). Small-sided games produced a trivial change in movement response time as well as in the Planned-AFL agility test (P > 0.05). The change-of-direction training produced small to trivial changes in all of the test variables (P > 0.05, effect size = 0-0.2). The results suggest that small-sided games improve agility performance by enhancing the speed of decision-making rather than movement speed. The change-of-direction training was not effective for developing either change-of-direction speed as measured by the Planned-AFL test or reactive agility.
 

 
Preconditioning strategies to enhance physical performance on the day of competition.

Kilduff, Finn, Baker, Cook, West (2013). Int J Sports Physiol Perform 8(6): 677-681

Sports scientists and strength and conditioning professionals spend the majority of the competition season trying to ensure that their athletes' training and recovery strategies are appropriate to ensure optimal performance on competition day. However, there is an additional window on the day of competition where performance can be acutely enhanced with a number of preconditioning strategies. These strategies include appropriately designed warm-up, passive heat maintenance, postactivation potentiation, remote ischemic preconditioning, and, more recently, prior exercise and hormonal priming. The aim of this review was to explore the potential practical use of these strategies and propose a theoretical timeline outlining how they may be incorporated into athlete's precompetition routine to enhance performance. For the purpose of this review the discussion is confined to strategies that may enhance performance of short-duration, high-intensity sports (eg, sprinting, jumping, throwing).



Tendon and skeletal muscle matrix gene expression and functional responses to immobilisation and rehabilitation in young males: Effect of growth hormone administration. J Physiol Nov 2013  

Boesen, Dideriksen, Couppé, Magnusson, Schjerling, Boesen, Kjaer, Langberg. J Physiol Nov 2013 [Epub ahead of print]

We examined the effect of growth hormone (GH) on connective tissue of tendon and skeletal muscle during immobilisation and re-training in humans. Young men (20-30 years; n=20) were randomly assigned to daily recombinant GH (rhGH)(33-50μg/kg/d) or placebo (Plc), and had one leg immobilised for two weeks followed by six weeks of strength training. Cross sectional area (CSA), maximal muscle strength (MVC) and biomechanical properties of m.quadriceps and patellar tendon were determined. Muscle and tendon biopsies were analysed for mRNA of collagen (COL-1A1/3A1), insulin-like growth factors (IGF-1Ea/Ec), lysyloxidase (LOX), matrix metalloproteases (MMP-2 and -9), decorin and tenascin-C. Fibril morphology was analysed by transmission electron microscope (TEM) to detect changes in fibril diameter distribution. In muscle the CSA and MVC declined with immobilisation, and recovered with rehabilitation similar in both groups. Likewise, both groups increased in IGF-1Ea/Ec and COL-1A1/3A1 expression in muscle during re-training after immobilisation compared to baseline, and the rise was more pronounced when subjects recieved GH. The tendon CSA did not change during immobilisation, but increased in both groups during six weeks of rehabilitation (~14%). A decline in tendon stiffness after immobilisation was observed only in Plc, and an increase during six weeks rehabilitation was observed only in GH. IGF-1Ea and COL-1A1/3A1 mRNA increased with immobilisation in the GH group only, and LOX mRNA was after immobilisation higher in the GH group vs Plc. Both groups increased in MMP-2 with immobilisation, whereas no changes in MMP-9, decorin and tenascin-C were observed. Tendon fibril diameter distribution remained unchanged in both groups. In conclusion, GH stimulates collagen expression in both skeletal muscle and tendon and abolishes the normal inactivity related decline in tendon stiffness and LOX, and results in an increased tendon CSA and stiffness during rehabilitation. GH has a matrix stabilising effect during periods with inactivity and rehabilitation in humans.

Sources: PubMed & the journals

Monday, November 4, 2013

Hot topics in Sport Science (Free downloads)



Muscular and systemic correlates of resistance training-induced muscle hypertrophy by Mitchell et al., PLoS One. 2013 Oct 9;8(10):e78636


VO2max Trainability and High Intensity Interval Training in Humans: A Meta-Analysis by Bacon et al., PLoS One. 2013 Sep 16;8(9):e73182

Wednesday, October 16, 2013

Why do humans vary in their responses to exercise training?

The concept of human variation in response to exercise training has been introduced about 30 years ago. Since the early 1980s a number of studies have supported this concept. In addition, several studies have shown that there is a genetic component that may explain the interindividual variation to training adaptations.

Professor Claude Bouchard, a pioneer on genetics of human adaptability to training, has summarized the available evidence in a review article last year.

You can download the paper from the Experimental Physiology at  http://ep.physoc.org/content/97/3/347.full.pdf+html

Saturday, October 5, 2013

How to build your case

I know from my experience that many sports scientists might face difficulties to persuade their managers or senior management of the power of their plans. To help you towards becoming more effective in your communication, I am quoating below a relevant tip by the Harvard Business Reviews. I have highlighted some points which, I think, are more crucial.


"To Build Your Case, First Identify the Business Need

Before you can build a compelling case for a new product or initiative at your company, make sure the business need is crystal clear. If your stakeholders don’t understand and agree with your explanation of the problem, they’re not going to approve it. Start by talking to the people who are directly affected by the problem and will therefore benefit from the solution. Ask them: When did the issue start? How does it manifest itself? Gather any relevant data, reports, surveys—whatever evidence they can provide. But don’t just take people’s word for it. If possible, observe the issue firsthand. Through conversations with your beneficiaries and your own observations, develop a full picture of the problem so your solution is that much more enticing."

Friday, October 4, 2013

How to assess bilateral strength assymetry

Most of the sport scientists use isokinetic strength assessments to evaluate bilateral strength assymetry. However, this method is expensive and time consuming. It can also be argued that both the speed and the mode of muscle action is far from what is happening in real life. It appears that performing a vertical jump test on a force platform is a good alternative. It is much cheaper and evaluates muscle strength assymetries with a functional test.

This test should be repeated for the left and the right leg unless you have a system with two synchronized force platforms. Impellizzeri and his colleagues (MSSE 2007) have used this test and suggested that the range of normal bilateral assymetry should by -15 to 15%. These normative values are from more than 300 Italian football players (professional, semi-professional and amateur level).

Friday, September 27, 2013

Chocolate milk for optimum recovery?



Low-fat chocolate milk consumption has been suggested as an effective strategy to speed up recovery after exercise. However, not all studies have shown a positive effect following chocolate milk consumption and this should be taken into consideration when applying these findings. For a comprehensive review you can read the article by Spaccarotella and Andzel

http://www.ncbi.nlm.nih.gov/pubmed/21993044

Everything is possible


foglobe.com

I believe that it is important to learn by example. That's why I decided to post the link below showing Roger Bannister to brake one of the man's greatest barriers; the 4 min mile. 

This historic event took place on 6 May 1954 during a meet between British AAA and Oxford University at Iffley Road Track in Oxford. It was watched by about 3,000 spectators.

It is an inspirational video that I hope all will enjoy!



Source: wikipaedia.com

Thursday, September 12, 2013

How to manage change? Lessons from Sir Alex Ferguson

Are you keen in learning keys for success from Sir Alex Ferguson? In this October’s edition of the Harvard Business Reviews Professor Anita Elberse and Sir Alex Ferguson collaborated to summarize key strategies to Ferguson’s successful career. These approaches apply to other places and life conditions. For me, it was an exciting time to read this paper. I have learned a lot.

Among others, you will read about:
  • The value of observing
  • How to manage change, and
  • How to make winners

You can access the publication at the Harvard Business Review website http://hbr.org/2013/10/fergusons-formula/ar/1

I am sure you will enjoy the reading too.
George

Wednesday, September 11, 2013

Which is the most effective method to improve football-specific decision-making?

seedspeed.com

Warren Young and Nathan Rogers from Australia investigated the effect of two different training methods on planned and reactive agility tests. Although the data are on Australian rules players, I think they apply also to football (soccer).

What they did?
  • 25 U18 players were randomly assigned to 2 training groups i) the change of direction group, ii) the small-sided game group.
  • Players performed 11 sessions, of 15 min each, in 7 weeks.
  • A planned-AFL agility test and a video-based reactive agility test were performed before and after intervention.



Main results
  • The small-sided games group improved total time in the reactive agility test and this was entirely due to a very large reduction in decision time.
  •  Small-sided games produced a trivial change in movement response time as well as in the planned-AFL agility test.
  • The change-of-direction training produced small to trivial changes in all of the test variables.

Conclusions
  • Small-sided games seems to improve agility and this may be due to better speed of decision-making.
  • The specific change of direction training was not effective in improving either agility or reactive agility, at least in this group of players.

Source
Young W and Rogers N. Effects of small-sided game and change-of-direction training on reactive agility and change-of-direction speed. Journal of Sports Sciences [Epub ahead of print 9 September 2013]

Monday, September 2, 2013

What’s new in sport science?

Skein M, Duffield R, Minett GM, Snape A, Murphy A. The Effect of Overnight Sleep Deprivation Following Competitive Rugby League Matches on Post-Match Physiological and Perceptual Recovery. Int J Sports Physiol Perform 2013; 8: 556-564.

School of Human Movement Studies, Charles Sturt University, Bathurst, NSW, Australia

This study examined the effects of overnight sleep deprivation on recovery following competitive rugby league matches.Eleven male, amateur rugby league players performed two competitive matches, followed by either a normal night's sleep (~8h; CONT) or a sleep deprived night (~0h; SDEP) in a randomised fashion. Testing was conducted the morning of the match, and immediately post-match, 2h post and the next morning (16h post-match). Measures included counter-movement jump (CMJ) distance, knee extensor maximal voluntary contraction (MVC), voluntary activation (VA), venous blood creatine kinase (CK) and C-reactive protein (CRP), perceived muscle soreness and a word-colour recognition cognitive function test. Percent change between post- and 16h post-match was reported to determine the effect of the intervention the next morning.Large effects indicated a greater post- to 16h post-match percentage decline in CMJ distance following SDEP compared to CONT (P=0.10-0.16; d=0.95-1.05). Similarly, the percentage decline in incongruent word-colour reaction times were increased in SDEP trials (P=0.007; d=1.75). Further, large effects indicated higher CK and CRP responses 16h post-match during SDEP compared to CONT (P=0.11-0.87; d=0.80-0.88).

Conclusion
Sleep deprivation negatively affected recovery following a rugby league match, specifically impairing CMJ distance and cognitive function. Practitioners should promote adequate post-match sleep patterns or adjust training demands the next day to accommodate the altered physical and cognitive state following sleep deprivation.


Argus CK, Driller MW, Ebert TR, Martin DT, Halson SL. The Effects of Four Different Recovery Strategies on Repeat Sprint Cycling Performance. Int J Sports Physiol Perform 2013; 8: 542-548.


Performance Recovery, Australian Institute of Sport, Belconnen, ACT, Australia

The aim of this study was to evaluate the effectiveness of different recovery strategies on repeat cycling performance where a short duration between exercise bouts is required. Eleven highly-trained cyclists (mean ± SD; age = 31 ± 6 years; mass = 74.6 ± 10.6 kg; height = 180.5 ± 8.1 cm) completed four trials each consisting of three 30 s maximal sprints (S1, S2, S3) on a cycle ergometer, separated by a 20-min recovery period. In a counter-balanced, cross-over design, each trial involved subjects performing one of four different recovery strategies; compression garments (COMP), electro-muscle stimulation (EMS), humidification therapy (HUM) and a passive control (CON). The sprint tests implemented a 60 s pre-load (at an intensity of 4.5 W·kg-1) prior to a 30 s maximal sprint. Mean power output (Watts) for the three sprints, in combination with perceived recovery and blood lactate concentration were used to examine the effect of each recovery strategy. In CON, S2 and S3 were (mean ± SD): -2.1 ± 3.9% and -3.1 ± 4.2% lower than S1. Compared to CON, COMP resulted in a higher mean power output from S1 to S2 (mean ±90%CL: 0.8 ±1.2%; possibly beneficial) and S1 to S3 (1.2 ±1.9%; possibly beneficial); whilst HUM showed a higher mean power output from S1 to S3 (2.2 ±2.5%; likely beneficial) relative to the CON.

Conclusion
We would suggest that both compression garments and humidification therapy may be effective strategies to enhance recovery between repeated sprint cycling bouts separated by ~30min.


Buchheit M, Al Haddad H, Simpson BM, Palazzi D, Bourdon PC, Di Salvo V, Mendez-Villanueva A. Monitoring Accelerations With GPS in Football: Time to Slow Down? Int J Sports Physiol Perform 2013; July 30 [Epub ahead of print]

Physiology Unit, Football Performance and Science Department, ASPIRE Academy for Sports Excellence, Doha, Qatar

The aim of the present study was to 1) examine the magnitude of between-GPS model differences in commonly reported running-based measures in football, 2) examine between-unit variability and 3) assess the effect of software updates on these measures. Fifty identical brand GPS units (15 SPI-proX and 35 SPI-proX2, 15 Hz, GPSports, Canberra, Australia) were attached to a custom-made plastic sled towed by a player performing simulated match running activities. GPS data collected during training sessions over 4 weeks from 4 professional football players (n = 53 files) were also analyzed before and after 2 manufacturer-supplied software updates. There were substantial differences between the different models (e.g., standardized difference for the number of acceleration >4 m.s-2 = 2.1; 90% confidence limits (1.4, 2.7), with 100% chance of a true difference). Between-unit variations ranged from 1% (maximal speed) to 56% (number of deceleration >4 m.s-2). Some GPS units measured 2 to 6 times more acceleration/deceleration occurrences than others. Software updates did not substantially affect the distance covered at different speeds or peak speed reached, but one of the updates led to large and small decreases in the occurrence of accelerations (-1.24;-1.32,-1.15) and decelerations (-0.45; -0.48,-0.41), respectively.

Conclusion
Practitioners are advised to apply care when comparing data collected with different models or units, or when updating their software. The metrics of accelerations and decelerations show the most variability in GPS monitoring and must be interpreted cautiously.


Bradley P, Carling C, Gomez Diaz A, Hood P, Barnes C, Ade J, Boddy M, Krustrup P, Mohr M. Match performance and physical capacity of players in the top three competitive standards of English professional soccer. Hum Mov Sci 2013; Aug 23 [Epub ahead of print]

Department of Sport and Exercise Sciences, University of Sunderland, UK

The aim of this study was to compare the match performance and physical capacity of players in the top three competitive standards of English soccer. Match performance data were collected from players in the FA Premier League (n=190), Championship (n=155) and League 1 (n=366) using a multiple-camera system. In addition, a selection of players from the Premier League (n=56), Championship (n=61) and League 1 (n=32) performed the Yo-Yo intermittent endurance test level 2 (Yo-Yo IE2) to determine physical capacity. Players in League 1 and the Championship performed more (p<.01) high-intensity running than those in the Premier League (Effect Size [ES]: 0.4-1.0). Technical indicators such as pass completion, frequency of forward and total passes, balls received and average touches per possession were 4-39% higher (p<.01) in the Premier League compared to lower standards (ES: 0.3-0.6). Players also covered more (p<.05) high-intensity running when moving down (n=20) from the Premier League to the Championship (ES: 0.4) but not when players moved up (n=18) standards (ES: 0.2). Similar Yo-Yo IE2 test performances were observed in Premier League, Championship and League 1 players (ES: 0.2-0.3). Large magnitude relationships (p<.05) were observed between Yo-Yo IE2 test performances and the total and high-intensity running distance covered in both Championship (r=.56 and .64) and Premier League matches (r=.61 and .54).  

Conclusion
The data demonstrate that high-intensity running distance was greater in players at lower compared to higher competitive standards despite a similar physical capacity in a subsample of players in each standard. These findings could be associated with technical characteristics inherent to lower standards that require players to tax their physical capacity to a greater extent but additional research is still required to confirm these findings.

Source: PubMed

Monday, August 19, 2013

Keeping your cool: strategies to improve football performance in hot conditions

Paul Laursen, Ph.D.
Performance Physiologist, High Performance Sport New Zealand
Adjunct Professor of Exercise Physiology, AUT University, New Zealand
paul@teknicool.com


Thanks to Dr Nassis for the invitation to write a guest post. What I’ll present herein are some facts around performance in the heat, along with some practical strategies we can use to improve a player’s performance and the effectiveness of play in such conditions. To begin, we should note that a hot environment is typically defined as an ambient/environmental temperature greater than 28°C.  As noted by Tyler and colleagues (2013) in the most recent review on the topic, the 2022 FIFA World Cup will be held in Qatar, where the conditions are expected to exceed 40°C, so optimising cooling strategies has been highlighted as a research priority by a FIFA-endorsed panel of experts (Grantham et al. 2010). It’s important therefore that collectively we are aware of the issues and strategies that can improve our player’s football performance and well being in the heat.

Scientific background – Why do we get hot?

Remember that when we do any form of exercise, we convert our stored food energy (carbs and fat) into the mechanical energy needed for movement. This is a relatively inefficient process, whereby 75% of that energy conversion gets turned into heat. When it’s cold out, that a good thing, as that metabolism keeps our body temperature up and processes working efficiently at the right temperature. But when exercise intensity is raised, and environmental temperature/humidity is high, the resultant can be a rate of heat gain that is greater than one’s ability to lose the heat, leading to an increased core temperature. Normal core temperature sits around 37°C, and a typical exercising temperature is around 38°C. Interestingly, our brain doesn’t typically let us exercise too much past 39-40°C. Studies show that once we get in this range, the brain sends stern signals for our body to reduce its efforts or stop altogether. And that’s a good thing because it recognizes the grave danger beyond this point, including the possibility of death at just 43°C.

So the reduced performance that happens when we exercise in the heat is a protective mechanism.  Our brain is saying to us, you’re producing too much heat, and we need to reduce that intensity or you’re going to harm us.  This happens subconsciously. Despite our desire to go harder, our brain just won’t let us.  Everyone experiences this reduced work rate, even the very best players out there – they just might experience less of a decline due to their efficient use of energy, leanness, and greater ability to rid the heat.

But that begs the question; if performance is key, what can we do to better football performance for our players in hot conditions?  The key practical points include heat acclimation, keeping cool before and during exercise, and shortening the warm-up.

Heat acclimatization

It’s always about the preparation. So it's probably not surprising that heat acclimatization is the most important thing you can do to better your performance in hot conditions. This means training in hot conditions in the days preceding the event in question. About the minimum you can get away with is 4 days, and an optimal time is considered to be more like 10 days, or longer if you can afford it.  In these sessions, you should be aiming to get hot during training for time periods ranging from 45-90 minutes or longer per day, depending on the fitness of your players/club. Sitting in a sauna (20-40 min) post-training is a good alternate method if a hot training environment isn’t possible.

As you spend accumulative days in the heat, for each consecutive day, your player’s heart rate and core temperature tends to be lower for a given exercise intensity, and sweat rates are higher. One of the main things going on in the body to cause this to occur is a rise in the water portion of your blood, called your plasma volume. So exercise feels easier, and players perform better after a number of days in the heat.

Cooling methods

You may have heard before that we’re comprised of about 60% water (we’re a water bath). So anything small we can do to either start cooler, or slow down the process of getting hot, tends to be conducive to bettering our exercise performance. Tyler et al. (2013) just published a meta-analysis on the topic in BJSM, and importantly showed that intermittent and prolonged exercise are improved with various cooling methods. Another recent review by Jones and colleagues (2012) highlight a number of effective ways you can go about lowering your body temperature before and during exercise, including cold water baths, hanging out in air conditioned rooms, wearing ice jackets, or drinking cold fluids or ice slushies. The main way these methods work is by increasing the amount of heat one can store before attainment of those aforementioned critical core temperatures. While all of these methods have shown some success, the only one that is usually of any practical benefit is the drinking of cold fluids and ice slushy concoctions before and during the game (Jones et al., 2012).   




Figure 1. Likely mechanism of ice slushies effect on thermoregulation.
  Ice slushy/cold fluid ingestion

The ingestion of cold fluids and ice slushy prior to exercise in the heat has received much interest of late. Siegel et al. (2010) were the first to show how the ingestion of 7.5 g/kg (~500-600 ml) 30 min before running in the heat at threshold, significantly increased run time by 19%, or about 10 min compared with drinking cold (4°C) fluids. For any given time point, subjects felt cooler and perceived the exercise as easier. The authors speculated that it was added heat removal from the phase change (solid ice to liquid water) that created the additional heat sink and cooler temperatures.  Another interesting finding from this study was that final core temperature was about 0.3°C higher at exercise completion, suggestive of the fact that the ingestion of ice slushy may exert its effect of improving exercise in the heat through the lowering of brain temperature, which could occur conductively due to the proximity of the mouth to the brain and associated arteries (Figure 1; Siegel & Laursen, 2012). 

Due to both its effectiveness and practicality, ice slushy ingestion is a good means of precooling athletes prior to and during (i.e., at half time) exercise in the heat. It has been shown to be just as effective as cold water immersion (Siegel et al., 2012), and it is much easier to implement compared with cold plunge baths and ice jackets. Plus, you gain the added hydration effects once the ice turns to water.

Shorten your warm-up

Undoubtedly, some form of warm-up is going to better your football performance. However, when it’s hot out, you run the risk of over-heating during your warm-up and storing too much of this heat before the game. Remember that starting at a lower body temperature will lower the time it will take for you to reach those critical, or very high core temperatures. Thus, if the temperature is hot, consider cutting your typical warm-up time in half. 

Summary

You’re going to get hot playing football this summer. The things you can do to improve your football performance in hot conditions include training in the heat in the days leading up to the competition (heat acclimatization), cooling yourself before the game and at half time using cold fluid or ice slushies, and shortening your warm-up. Remember that the coaches and support staff can get hot and bothered too, so similar advice holds true for the entire team to allow the best collective performance.

Take home points

1) Prepare your team by training in the heat in the days leading into competition in hot environments (i.e., 4-10 days our, or longer). A 20-40 min sauna post-training is a good alternate method of heat acclimating if you can’t train directly in the heat.
2) Get players to ingest about 7.5 g/kg (500ml) of ice slushy drink or ice cold fluids in the 30-40 min period prior to the game. This will allow them to be cooler before play (ice slushy lowers core temperature by about 0.3-0.5°C). 
3) Abbreviate your warm-up duration and intensity by about 50%.
4) Drink another 300 ml (to thirst) of ice slushy during the half time break to get another small reduction in body heat content.

Follow this advice and keep your cool!


References

1. Grantham J, Cheung SS, Connes P, Febbraio MA, Gaoua N, González-Alonso J, Hue O, Johnson JM, Maughan RJ, Meeusen R, Nybo L, Racinais S, Shirreffs SM, Dvorak J. Current knowledge on playing football in hot environments. Scand J Med Sci Sports 2010;20(Suppl 3):161–7.
2. Jones PR, Barton C, Morrissey D, Maffulli N, Hemmings S. Pre-cooling for endurance exercise performance in the heat: a systematic review. BMC Medicine 2012;10:166.
3. Siegel R, Laursen PB. Keeping your cool: possible mechanisms for enhanced exercise performance in the heat with internal cooling methods. Sports Med. 2012;42(2):89-98.
4. Siegel R, Maté J, Watson G, Nosaka K, Laursen PB. Pre-cooling with ice slurry ingestion leads to similar run times to exhaustion in the heat as cold water immersion. J Sports Sci. 2012;30(2):155-65.
5. Siegel R, Maté J, Brearley MB, Watson G, Nosaka K, Laursen PB. Ice Slurry Ingestion Increases Core Temperature Capacity and Running Time in the Heat. Med Sci Sports Exerc. 2010;42(4):717-25.
6. Tyler CJ, Sunderland C, Cheung SS. The effect of cooling prior to and during exercise on exercise performance and capacity in the heat: a meta-analysis. Br J Sports Med. 2013 Aug 14. doi: 10.1136/bjsports-2012-091739. [Epub ahead of print]