What the experts say
Nigel Hetherington reviews the latest research material relating to coaching, exercise physiology and athletic development.
As a highly complex system the human body is prone to a host of potential injuries depending on the activity and the state of the body. It is well recognized and reported that appropriate strengthening and stabilization of the body can reduce the injury risk to soft tissue both in short-term explosive activities and longer-term pure fatigue based activities. The old saying "you cannot fire a cannonball from a canoe" holds true and conjures up a colourful image!
In order to avoid injury it is as well therefore to understand when it may arise and what may cause it. A recent study based on video data over a 12 years span taken from female Norwegian handball games revealed that for 32 anterior cruciate ligament injuries a high proportion (80%) occurred when the knee was twisted (external or internal rotation of the tibia) while almost fully extended - this occurred during either plant-and-cut moves or 1-legged jump shot landings. Clearly, many sports involve such movements and therefore run high injury risks, especially team field games, individual racquet sports, some field events in athletics - particularly the throws, as well as perhaps less obvious ones such as high speed running turns using so-called reverser boards in Sportshall athletics. A further study based on data from the US, Scandinavia and now the UK shows somewhat alarmingly that female footballers are between 2 to 6 times more likely to suffer an anterior cruciate ligament injury than their male counterparts. In the wake of the Rugby Union World Cup in 2003 an article concludes that it is a certainty that with an increased interest in playing the game there will be an increase in the number of injured players. The article goes on to look at the biomechanics and the areas of greatest injury risk and provide guidance on the physiotherapist's role as part of the medical team.
Core stability was tested pre-season in a large group of 80 women and 60 men involved in intercollegiate basketball and track athletics with view to establishing the relationship between specific areas of strength or weakness and any injury occurrence. The measures involved included hip abduction and external rotation strength, abdominal muscle function along with back extensor and quadratus lumborum endurance (muscle involved in respiration and lateral trunk flexion - raising the hip).
Both males and females with higher strength measures in these areas tended not to incur injuries against their less stable counterparts. The best measure of reduced injury potential was viewed as hip external rotation strength. The potential value of this indicator to injuries in the lower limb joints is supported by a paper which directly relates patellofemoral (anterior knee) pain to weaknesses in hip abduction and external rotation based on a study of 15 female subjects aged 12-21 years. Subjects prone to knee pain were up to 36% weaker in hip external rotation strength than those not prone to pain or injury. Clearly stabilization around the hip area is crucial to avoiding injury in the lower limb joints.
Specifically relating to the anterior cruciate ligament (ACL) a further two studies have identified that a high proportion of competitive athletes (62 from 77) were able to return to competition with 12 months of surgery (ACL reconstruction) with 55 of these returning to the same level as before. 13 of these still however, reported pain. In a different study  the effectiveness of ACL reconstruction was tested for specific rapidly applied forces during downhill running 4 to 12 months after surgery using a stereo-radiographic system. Final analysis revealed that reconstructed knees continued to exhibit greater external rotation by an average of 3.8 degrees across all subjects relative to individuals with uninjured limbs. Reconstructed knees were also more adducted by an average of 2.8 degrees. ACL reconstruction appears to fail to restore normal rotational knee kinematics as measured during dynamic loading.
The best solution is clearly 'prevention', possibly with improved core stability through specific strengthening as described above, rather than 'cure' through surgical treatment. Furthermore, the likelihood is that better stability will not only reduce the incidence of injury and hence increase the capacity for quality training but will also impact on the specific biomechanics of the event and potentially lead to a higher level of performance.
One thing though has been clarified recently on which basic science and clinical studies agree. Active treatment of injuries is essential to effect complete recovery and recovery in the optimum time. Too many athletes are still being advised to immobilize an injured area for several weeks whereas current experience and knowledge actually base treatment on a short period of immobilization followed by controlled and progressive mobilization.
Without this active treatment regime it is likely that the injured area may never return to full function and strength. The role of the physiotherapist in such treatments is obvious and the coach should encourage professional treatment at the very earliest stage. Excessive muscle tone or tightness can lead to injury when conflicting forces are in operation from the antagonists to these muscles. In young athletes excessive muscle tone may simply be a function of bone growth through a pre-pubescent or late adolescent growth spurt where the rate of bone growth exceeds that of muscle elongation. Appropriate levels of muscle flexibility can, therefore, help to reduce the risk of injury. The hamstring muscles - the biceps femoris, semitendinosus and semimembrinosus are particularly susceptible to injury in high speed running activities.
A recent study compared static hamstring stretching (3 x 30s seated with pelvic tilt) and a 20 minutes application of moist heat (160 degree F moist pack) directly to the hamstring muscles. Passive Goniometer-based measurements showed that the moist heat application was superior for generating the greatest hamstring flexibility. A further reference to hamstring flexibility is made through the impact of massage on performance of the standard sit and reach test. Despite commonly held beliefs, a massage treatment lasting 15 minutes had no impact on sit and reach measurements based on 11 male subjects compared to those who had simply rested supine for the same period.
In support of the above hamstring flexibility study published literature was reviewed on the role of massage for the treatment of delayed-onset muscle soreness (DOMS) - the result of muscle damage occurring after strenuous exercise. The broad findings were that although in around 75% of the papers athletes reported reduced muscle soreness only one study found that massage improved muscle function.
This ties in well with the sit and reach findings above. Furthermore, levels of inflammation appeared not to be affected by massage. The use of non-steroidal anti-inflammatory drugs (NSAID's) is quite common to combat pain and swelling associated with DOMS and muscle injury.
This review reports that the use of such drugs may hinder the healing process and affect long-term muscle adaptation, so important to athletes in their development. Furthermore, unwanted physiological side effects may also occur including gastrointestinal and renal complications. A parallel review basically concludes that the use of NSAID's is simply not warranted. A further review examined the case for prevention of DOMS following strenuous exercise. The main conclusion is that adapting the body more effectively to eccentric stresses can reduce the impact of DOMS.
A further review expanded on this and enforced the need to allow one to two days of reduced intensity training following activities likely to invoke DOMS. In other words better and more appropriate and specific training including resistance loading and progressive time-based training more in keeping with the capability of the body to adapt to the overload applied and to allow adequate recovery rather than continue to produce the DOMS effect in training or competition. Finally, in this review series another set of authors  looked at the effect of chronic muscle damage from repeated exercise bouts and the effect this has on the ability of the body to continuously remodel skeletal muscle. Ultimate limitations do exist and there appears to be a point at which the capacity for repair and adaptation is exhausted.
Notwithstanding the fact that prevention through appropriate conditioning or 'prehab' is better than cure the reality is that injuries will continue to occur in sport. Appropriate and well-planned treatment regimes are therefore of massive importance to athletes who always want to get back to full training and competition in the minimum time.
Chronic groin pain is prevalent in many athletes in many different sports and often goes undiagnosed. In a recent study in the Netherlands a group of 14 athletes whose groin pain remained undiagnosed were referred for further examination. 10 of these complained of unilateral and 4 of bilateral pain. The study identified the fact that almost all athletes were suffering from an operable hernia of one form or another, which were all subsequently treated successfully with surgery. Such operations can return an athlete to full sport within 3 months.
An athlete's worst nightmare is re-injury and it is a fact that most injuries that athletes suffer fall into this category. Ankle sprains are a common case in point. A recent publication highlights the use of a bi-directional bicycle pedal to improve performance in previously weakened and unstable ankles. A study of 19 subjects showed 14.2% increases in peak eversion torque, 0.24s reduction in figure of 8 running around a small circuit and improved single leg stance speed. Athletes with recurrent ankle sprains can benefit from such training.
Finally, on the basis that a fatigued body is more prone to injury and that the feeling of persistent fatigue is very depressing it is refreshing to know that our physical leisure time activities actually do help prevent the onset of persistent fatigue - those of us who take part in sport already know that but in a paper from Norway it is actually finally proven!
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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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