What the experts say
Nigel Hetherington reviews the latest research material relating to coaching, exercise physiology and athletic development.
The old adage 'Prevention is better than cure' was never more relevant than in the prevention of injury to sportspeople. No one has time to be injured. Setting aside the freak accident that will always happen from time-to-time, however careful we may act and however knowledgeable we may become, there are a host of approaches that need to be considered in injury prevention. This month, for example, we take a look at papers reporting on different types of injuries and their potential causes as well as intervention programs designed to reduce injury such as education through video exposure, specific training and psychological profiling.
We go on to take a look at major risk groups and key risk factors - identifying these can, once again, allow the opportunity for application of appropriate injury prevention strategies. Reports offering screening techniques and specific conditioning approaches are then reviewed finishing off with details from several papers on clinical approaches. The final paper reviewed takes a more holistic approach to injury prevention and poses an interesting question.
At one end of the spectrum of injury causes is 'collision' and a paper looking at ice hockey revealed that 65% of all injuries occurred during games and, of those, around 50% arose resulted from collisions during actual games either between players or between player and boards. This means that one third of all injuries to ice hockey players occur as a direct result of collision during match play. The question that should be asked at this point is 'Is this level of injury acceptable?' If not then further measures are required. What else can be done?
A different study looked at the causes of head injuries in elite football (soccer) players. Not surprisingly, it concluded that from 112 cases of head injury, 58% were caused during collision between players and, of these a high elbow caused 79 cases. The report asks the question 'should rules be more strictly applied or even should rules be changed to protect players?'
One approach that completely failed to show any positive outcome was the use of a video-based awareness program with elite male soccer players from Iceland. The program included a 15-minute presentation with information on the injury risk of playing elite soccer, typical injuries, and their mechanisms. Then the players worked together in pairs and analyzed video sequences to develop preventive strategies. Absolutely no change in injury occurrence, rate and type was observed throughout the following football season in comparison with the two previous seasons.
Success did, however, arise from a program in Sweden, where 32 high-risk soccer players, identified from various psychological profiling scales for anxiety, life events and coping skills, were split into either a treatment or control group. The group treated with a 19-week program of mental skills development in 6 different mental areas, significantly lowered their occurrence of injury relative to the control players as measured in subsequent play.
A physical approach that also showed measurable success was applied to rugby league players. Based on a specific tapering of pre-season training loads with a group of 220 sub-elite players over 3 years, with controls in place, the players who underwent the tapering demonstrated a significantly lower injury rate.
Incidentally, the same players also showed an increase in maximal aerobic power. These results suggest to me, at least in part, that taking account of overload / adaptation / recovery actually works since surely, fitter and better-rested players are more likely to avoid certain types of injury?!
Classification of risk groups and prioritizing these can also help to prevent injury so it may come as a surprise to find that if you have a family member with an anterior cruciate ligament problem you are more than twice as likely as anyone else to suffer a related problem! This was the finding from a study that looked at matching patients with diagnosed problems with similar people i.e. taking account of gender, age and primary sport.
On a similar tack complete Achilles tendon ruptures are found more often in athletes who participate in sports involving explosive acceleration or maximal effort. In most studies, the consensus for athletes is surgery. This form of treatment has been shown to exhibit the best functional performance with a lower re-rupture rate. A study highlighted the fact that younger sports people under the age of 30 are highly likely to re-rupture the tendon whereas it is almost unheard of for sportspeople older than 30 to have such a recurrence. Interestingly, having concluded this, the authors then point out that the older group all received surgery on average 2.65 days after injury whereas the younger group's delay was longer at 7.1 days. Could this delay prove critical in rehabilitation and a return to full strength?
Hamstring injuries continue to be all too common and a study from Australia throws yet more light on this area. Footballers studied showed a 20% incidence of hamstring injury as their first injury of the season. Once this data was adjusted for overall game exposure both increasing age and decreased quadriceps flexibility were significant predictors in hamstring injury. This fact specifically applied to players over 23 years of age. Players with increased quadriceps flexibility, as measured with the modified Thomas test, were less likely to suffer hamstring injury
In relationship to endurance activity a study points out that although the human body has a remarkable ability to undergo soft tissue repair and adaptation as a result of endurance training there may be a limit. In other words a point at which the body can no longer support adaptive repair and chronic injury or loss of muscular function may set in.
The paper reports on some clear relationships between training intolerance and long-term, high volume training but concludes that further research is essential to gain a fuller understanding. Maybe more quality, less volume is the answer to this conundrum?
Many a coach may decide there is little they can do rectify certain physical traits and continue with broadly appropriate training that may benefit the athlete in other ways. However, poor biomechanics and sub-optimal technique can lead to injury if the reason is not understood or rectified. One example of this is the fact that a lower limb valgus alignment (knock-kneed status) has been shown to lead to anterior cruciate ligament injuries. The Drop-Jump Screening test with video analysis was used to compare such alignment in a large group (325 females and 130 males all aged 11 to 19) of athletes. The drop jump revealed that 80% of female and 72% of male participants showed a true reduction in knee separation on landing suggesting a valgus alignment (and hence the potential for cruciate ligament injury). When a sub-set of 62 female athletes subsequently underwent a specific neuromuscular training program their knee separation increased from 23cm to 29cm, which was also measurably greater than the untrained boys at 22cm. This more 'neutral' lower limb alignment is strongly believed to lead to a lower injury incidence.
As ever, there is a caveat emptor factor when it comes to training to avoid injury or indeed to simply develop a specific fitness component. A paper reports that based on a study of ground reaction forces in school based jump training that children appear able to attenuate the impact forces associated with higher jumps - a self-defence mechanism that may also serve to inhibit the training effect being sought after. More rehabilitation than prevention but an interesting paper looking at the condition of patellar tendinopathy (an injury characterized by pain in the large tendon just below the kneecap) demonstrated use of a novel declined squat (with the heals raised on a platform) protocol to facilitate recovery worked better than the traditional 'flat footed' squat in terms of overall return of function particularly with those who continue to train and play in pain.
In issue 18 of Successful Coaching we reported on the effect of a proprioceptive balance board training program for the prevention of ankle sprains. The author has published a related paper looking at the cost-effectiveness of such treatment in volleyball where players were asked to evaluate all costs associated with not playing and injury treatment whether it included use of the balance board or not. The total cost per player was higher in the intervention group and the cost of preventing one ankle sprain was more than 10 times the individual cost to a member of that group. Aiming treatment only at those players who had previously suffered a sprain was the most cost-effective approach.
In a broad review of the clinical literature on acute muscle injury a paper once again spells out the general risk factors as being previous recent muscle injury and past muscle injury, decreased muscle strength (mainly eccentric muscle strength), muscle imbalance (decreased eccentric (antagonist) to concentric (agonist) muscle strength), decreased musculotendinous flexibility, increased age, and increased training load. Many of these factors can be attenuated or dealt with this prior knowledge.
The same author reviews chronic muscle strains and once again reports that a history of injury is very common. Together these papers support the notion that complete and appropriate treatment and rehabilitation is fundamental in avoidance of repeat injury. The challenge is to recognize that the level of function required by the sports participant is usually measurably higher than that of the average patient and that full performance can only be achieved following extensive and progressive rehabilitation.
Finally, a thought-provoking paper points out that science and medical researchers and practitioners working in the field of sports injury prevention tend to have very tangible objectives and focus on identifying and solving specific injury risks. There is an uncertainty, however, that "solving" one problem may not simply create another. As the field matures, it is worth considering whether theories and models can be developed that have more general application to a range of injury issues. The author suggests there is a need for an integrated perspective on sports injury that is inclusive of medical, behavioural (psychological, sociological, and organisational), physiological, and biomechanical factors. On the one hand, training and skills development are advocated as the best methods to reduce injury, but injury rates appear only to increase the more competitively a person approaches sport. This leads to the questions: are significant reductions in sports injury risk possible at all?
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About the Author
Nigel Hetherington is the Head Track & Field Coach at the internationally acclaimed Singapore Sports School. He is a former National Performance Development Manager for Scottish Athletics and National Sprints Coach for Wales. Qualified and highly active as a UK Athletics (UKA) level 4 performance coach in all events he has coached athletes to National and International honours in sprints, hurdles as well as a World Record holder in the Paralympic shot. He has 10 years experience as senior coach educator and assessor trainer on behalf of UKA. Nigel is also an experienced athlete in sprint (World Masters Championship level) and endurance (3-hour marathon runner plus completed the 24 hour 'Bob Graham Round' ultra-endurance event up and down 42 mountain peaks in the English Lake District). He is a chartered chemist with 26 years' experience in scientific research and publishing.
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