Sir,

This is likely to be the definitive trial on the effectiveness of pre-exercise stretching for some time, so it is important that it is carefully reported and analysed in this paper by Jamtvedt et al. I have a few questions.

t is stated that “two primary outcomes and 12 secondary outcomes were specified a priori in the analysis plan” but only the two primary outcomes and five secondary outcomes appear in the paper. Four secondary endpoints (three reported in the paper) are listed in the trial protocol registered with the Australian and New Zealand Clinical Trial registry, accessible here. Five
secondary endpoints (three reported in the paper) are listed in the protocol available on the trial website, accessible here. In that protocol the second of the two primary endpoints (time to injury) is subdivided in a number of ways that, with the exception of whether the participant sought help from a professional, differ from the analyses reported.

The reported secondary analysis of “time to injuries to muscles, ligaments and tendons” differs from the pre-specified secondary outcome in both protocols of “time to injuries that might be considered could be preventable by stretching”? In the website protocol it is stated that this “preventability” classification would be done without knowledge of the trial group. Can the authors clarify whether this was done?

Can they also clarify which outcomes were pre-specified in the analysis plan before the trial allocation code was broken, can they report all these outcomes, and state what adjustment was made for multiple tests of statistical significance?

These questions may sound pedantic, but the primary outcome for injury was negative. The apparent effect on muscle ligament and tendon injuries was of only modest statistical significance (P=0.03), and might disappear if adjustment was made for multiple significance testing. The apparent effect on the “bothersome soreness” is unavoidably susceptible to reporting bias in an open trial. The higher rate of dropout from follow-up at all time points in the experimental group, which appears unlikely to be due to chance, might bias the results in either direction.

As a participant, I was impressed with the trial organisation and design. Without reassurance that analysis and reporting were of an equally high standard, I remain fearful that the authors’ conclusion that “stretching … probably reduces the risk of some injuries and does reduce the risk of bothersome soreness”, is too strong.

Jim Thornton
Nottingham
June 2009

This article relates the personal experience of a well-known Australian sports physician. Although thromboembolic events are reasonably uncommon among our athletes, flying is almost ubiquitous in our profession so this has more relevance than some of us might have anticipated when studying the clotting cascade in medical school.

Peter Brukner’s Personal Perspective from MJA

A recent email from a reader detailed how she used a computer application to convert text from the online edition of the BJSM to an mp3 audio file so she could listen to it while running. She used a piece of software called Visual Text to Speech MP3, but there are a number of similar applications for both Windows and Mac.

Because this is such a great idea for busy people on-the-go, I’ve provided some links that I think will be helpful for those who want to give this a try for themselves. Remember to check the system requirements for any application you are thinking of purchasing to ensure that it will work on your particular system.

For Windows:

Visual Text to Speech MP3
TextAloud

For Mac:

Ghostreader
Text to Speech to MP3
Books2burn.

Enjoy keeping physically active while motoring through your favourite BJSM content! And I promise more podcasts to come as well!

Consensus Statement on Concussion in Sport: the 3rd International Conference on Concussion in Sport held in Zurich, November 2008

It’s out! You can stop banging your head against a brick wall in frustration. Hosted by a chapter of editors of various journals, the much-awaited Consensus Statement is out. If you are into concussion, if you treat boxers, football players, heavy metal fans who head bang, then this is for you. Vienna – OUT. Prague – OUT. Passe, done, finished kaput. The equivalent of flares and a brown suede coat for a contemporary wedding.

Zurich – BJSM carries the joint statement but also the excellent key papers that made the event unique and innovative; papers the contributed to the group drawing the conclusions they did. Download the SCAT document and side-line scoring system. Everything you wanted to know about concussion – right here, right now – BJSM Concussion. Comment on the Blog or via eletters – Do these guidelines work for you? What else do you need to take care of your athletes?

Proceedings of the 3rd International Concussion Consensus Conference
HYPERLINK “http://bjsm.bmj.com/content/vol43/Suppl_1/” http://bjsm.bmj.com/content/

By Justin A Paoloni

I read with interest the Consensus Statement on Concussion, and believe this worthwhile in furthering scientific knowledge on concussion in sport. However, I have concerns about definitive comments in the consensus statement, given the lack of supporting scientific evidence. Whilst this consensus document is only “a guide and is of a general nature consistent with the reasonable practice of a healthcare professional”, it is also “reflects the current state of knowledge”. This comment does not accurately represent the documents’ contents with definitive statements not evidenced based.

I agree with the preamble; “management and return to play decisions remain in the realm of clinical judgement on an individualized basis”, as scant high level evidence is available on concussion management. However, Section 2.2 states that “a player with diagnosed concussion should not be allowed to return to play on the day of injury. Occasionally, in adult athletes, there may be a return to play on the same day of injury (see Section 4.2)”, which follows with “adult athletes, in some settings, where there are team physicians experienced in concussion management and sufficient resources…return to play may be more rapid.” These statements have multiple qualifiers, but do not represent the management of concussion in sport. More than “occasionally” do athletes return to play on the same day after medical assessment and symptom resolution, and this appears safe and effective. The return to play decision does not require the “sufficient resources” mentioned, but does require a physician experienced in concussion management. Certainly, there are no scientific studies, and no comparison studies, with high enough level of evidence to definitively support either approach.

Section 11 states that “the consensus statement is intended to serve as the scientific record of the conference”. Thus, these definitive statements on concussion management, from an expert panel, require supporting scientific evidence and appropriate referencing, as for any scientific paper. To make these statements without quoting relevant high level evidence is not scientific. There are potential legal ramifications for medical practitioners who do not follow these concussion management guidelines.

I very much enjoyed reading the ‘warm up’ article by Steven N Blair in the January edition of BJSM. The first study that he quoted on attributable fractions for all cause deaths was a real eye popper!

I was very surprised to see that low cardiorespiratory fitness was a greater attributable risk factor (in both sexes) than obesity, smoking, high cholesterol, and diabetes, as well as hypertension in women.

The second study was almost equally as fascinating. This illustrated that the risk of cardiovascular mortality in Type 2 diabetes in the obese category who took moderate to high levels of exercise, was half that of diabetics in the normal weight category who took no exercise. There was one thing that puzzled me and that was the histograms illustrated that for the type 2 diabetics who took low levels of exercise the cardiovascular risk was the same for those in the obese category as in the normal weight group.

This article will certainly alter the way that I communicate health promotion to my patients, and I would like to congratulate Steven Blair for such a stimulating article.

By Bethany B. Barone and Kerry J. Stewart, Johns Hopkins University

The use of absolute versus weight standardized maximal oxygen consumption during fitness testing has been debated, especially in the context of intervention trials that may induce weight change. We recently showed that exercise training-related changes in exercise systolic blood pressure (SBP) were independently predicted by changes in fatness (by waist circumference) and fitness (by VO2peak in mL/min.kg).

Dr. Shephard correctly points out that reductions in weight could increase VO2peak adjusted for weight without absolute increases in fitness and commented on our use of fitness standardized to weight rather than absolute change in fitness. Though our 6-month exercise-only intervention was associated with minimal weight loss compared to controls (-1.8 kg), we did repeat our analysis using change in absolute fitness to address his concerns.

Our original analysis found that each 1.0 ml/kg.min increase in VO2peak and 1.0 cm decrease in waist circumference independently predicted a 1.0 mm Hg decrease in exercise SBP (p=0.04 and p=0.001, respectively). When we repeated this analysis using maximal absolute oxygen consumption, results were consistent with our original report. A 100 ml/min increase in VO2peak was associated with a 1.1 mm Hg decrease in exercise SBP (p=0.057); a 1.0 cm decrease in waist circumference was associated with a 1.2 mm Hg decrease in exercise SBP (>0.001). Therefore, we affirm our original conclusions that increased fitness has a beneficial effect on exercise SBP beyond weight loss.

“Effects of left- or right-hand preference on the success of boxers in Turkey”, is an interesting and important addition to the research literature on the effect of handedness in sport. However, we believe that the explanation of the cause of the advantage of left- handedness is misleading and needs correction.

Gursoy attributes the superior performance of left-handed boxers to ‘superior spacio-motor skills’ and links this to neurological factors and brain lateralisation. A more prosaic alternative explanation is not mentioned, namely a frequency-dependent advantage accruing to the individuals of the minority disposition simply by virtue of their minority status1,2 . Consider a right-hander competing against a left-hander: the right-hander has had less experience facing left-handers than his opponent has had facing right-handers. The left-hander is therefore at an advantage.

Support for this interpretation is provided by the observation that the advantage accruing to left-handers does not appear to extend to ‘non- interactive’ sports, where opponents compete separately and in sequence 3,4 . For example, no advantage appears to operate among darts players or ten-pin bowlers 5 . In these sports, a competitor’s unfamiliar handedness is unlikely to have an effect on the performance of his opponents. However, ‘superior spacio-motor skills’ of the sort implicated by Gursoy as underlying the effects observed would presumably still be of value.

The results of Gursoy’s paper are particularly interesting from an evolutionary perspective. A frequency-dependent advantage accruing to left -handed individuals in male-male combat has been hypothesised to explain the evolution of a balanced polymorphism of handedness during human evolutionary history 6,7 . Although the apparent advantage accruing to left-handedness in combat has been observed by fencing masters as early as the sixteenth century 8 , to our knowledge Gursoy’s paper is the first to rigorously demonstrate an advantage in combat and adds empirical support to this theory.

1 Wood CJ, and Aggleton JP. Handedness in ‘fast ball’ sports: do left -handers have an innate advantage? Br J Psychol. 1989; 80(2):227-40

2 Brooks R, Bussiere L, Jennions MD, Hunt J. Sinister strategies succeed at the Cricket World Cup. Proceedings of the Royal Society Series B (Biology Letters, Supplement) 2003 271: S64-S66

3 Raymond M, Pontier D, Dufour A and Møller AP. Frequency-dependent maintenance of left-handedness in humans Proc R Soc Lond B 1996 263: 1627- 1633

4 Grouios G, Tsorbatzoudis H, Alexandris K and Barkoukis V. Do left- handed competitors have an innate superiority in sports? Percept Mot Skills 2000 3(2): 1273-822000

5 Aggleton, J. P. & Wood, C. J. Is there a left-handed advantage in ‘ballistic’ sports? International Journal of Sport Psychology, 1990, 21, 46-57.

6 Billiard S, Faurie C and Raymond M. Maintenance of handedness polymorphism in humans: a frequency-dependent selection model Journal of Theoretical Biology 235(1), 7 July 2005, Pages 85-93 2005

7 Faurie C and Raymond M Handedness, homicide and negative frequency- dependent selection Proc. R. Soc. B (2005) 272, 25–28

8 Harris, Lauren Julius (2007). In fencing, what gives left-handers the edge? Views from the present and the distant past. Laterality: Asymmetries of Body, Brain and Cognition, 99999 (1), 1-41. Retrieved February 24, 2009, from http://www.informaworld.com/10.1080/13576500701650430

By May Arna Risberg, Havard Moksnes, Annika Storevold, Inger Holm, and Lynn Snyder-Mackler

I work in the rehab field by 18 years with a direct experience of ACL rehabs of more than 600 cases. It’s absolutely normal that after 60 days people can’t jump like before surgery. In my experience, I use testing ACL patients, first time, after 90 days from surgery for side to side impairment with isokinetic, electronic balance board and jump test with optic fiber. Often in the first two tests we find an average good balance.It’s not the same for the jump test. Usually we start dynamic rehab later for post surgery purposes.

That’s the reason because after 60 days is very difficult to have a complete recovery, even in a functional movement like the jump. And that’s the reason because is very difficult come back to competition before than four months, especially in the pivot-shift sports.

Kind regards,
Fulvio Stradijot

3-7 June 2009, Vancouver: The Road to 2010 begins in Vancouver in 2009
Website: casm-acms.org/

14-17 October 2009, Brisbane: Be active ’09 Australian Conference of Science and Medicine in Sport
Website: sma.org.au/acsms/

18-22 October 2009, Couran Cove, South Stradbroke Island: 24th ACSP Annual Scientific Conference
Website: acsp.org.au

12-28 February 2010, Vancouver: XXI Olympic Winter Games
Website: olympic.org/uk/games/vancouver/

14-26 August 2010, Singapore: 1st Summer Youth Olympics
Website: singapore2010.sg

12-27 November 2010, Guangzhou: 16th Asian Games
Website: ocasia.org

27 July – 12 August 2012, London: Games of the XXX Olympiad
Website: olympic.org/uk/games/london

7-23 February 2014, Sochi: XXII Olympic Winter Games
Website: olympic.org/uk/games/sochi/