What the experts say
Nigel Hetherington reviews the latest research material relating to coaching, exercise physiology, and athletic development.
Whether professional, semi-professional, or funded in some other way via the sport, through sponsorship, or from personal means, an increasing number of athletes and their coaches are tapping into the ever-growing range of offerings available from sports science support teams.
This means that the potential benefits of advice on physiology and nutrition, injury prevention, strength conditioning, and even biomechanics as well as the always-stimulating field of sports psychology are being utilized to an increasingly wider extent. Add to these lifestyle management support options, i.e. those previously run under the title of 'Athlete Career and Education' (ACE) and now widely referred to as 'Performance Lifestyles', and athletes are faced with a vast source of potential support (and some would argue confusion) to help them achieve their goals.
In this month's review, we take a snapshot of some of the latest papers and reports relating to this form of 'buy-into' support and try to untangle some of the complexities.
Recent papers reviewed relating to the field of athlete physiology include one that looks at the factors relating to 'overtraining syndrome'. Though still not fully understood the point about this condition is that performance can be badly affected, stress levels increase, the ability to train decreases; sleep and mood patterns are disrupted. Health can start to slide due to an impact on the immune system and a whole host of associated 'disorders'. Alarm bells should be ringing for coaches and athletes, but they are not always easy to hear in the early stages. The best recommendations from the paper are to watch out for changes in maximal heart rate and work output at 110% of the anaerobic threshold. However, this already moves things outside of the realistic zone of measurement and assessment for many. On a more practical note self-analysis by the athlete in terms of perceived fatigue and stress levels are very strong indicators of the onset of overtraining syndrome. If objective and subjective feelings are recorded in the athlete's log routinely, then there is a reasonable chance of hearing that alarm bell in time.
Much publicity has been given in recent times to altitude training to enhance the blood's oxygen-carrying capacity via increased haemoglobin levels. A recent publication highlights the fact that, based on a study of South American women of differing physical fitness levels from different altitudes versus German women from low altitudes, there was no impact on haemoglobin mass (i.e. overall amount rather than concentration) apparent at altitude without training. Furthermore, aerobic performance capacity was lower at altitude in untrained individuals. In other words, prolonged stays or living without exercise at high altitude will not necessarily lead to adaptation by the body, and tan appropriate exercise regime is important that can lead to increases in haemoglobin mass and hence oxygen-carrying capacity.
Hyperbaric oxygen therapy (HBOT - i.e. breathing 100% oxygen at pressures of up to 3 atmospheres) is used in various medical treatment regimes. A recent paper looked at the use of such treatment in eccentric muscle injury recovery based on principles established in a range of therapeutic medicine. The outcome was quite conclusive in that there was no measurable effect and that this line of treatment is not warranted for the treatment of eccentric muscle injury.
The interface between diet and physiology is an obvious one and a recent paper looking into serum testosterone levels in men demonstrated that during heavy resistance training both serum testosterone and free testosterone levels were affected negatively by a diet containing insufficient fat and /or excessive protein. This may serve as a warning to athletes involved in such conditioning programs not to stray too far away from balanced diets containing suitable levels of fat and also not to become too obsessed with high protein diets.
Moving on to injury prevention, identification, and treatment, a recent paper expands on earlier reports on the use of non-steroidal anti-inflammatory drugs (NSAID's) and reports on the findings of many papers to clarify recommendations for their use. When used in the treatment of exercise-induced muscle injuries, NSAID's should be given no sooner than 48 hours afterward to provide analgesia and to reduce early inflammatory damage (appropriate R.I.C.E. regimes only should be administered in the very early phase). Prolonged use (beyond seven days) is not recommended either since there is the possibility that they will delay muscle regeneration.
Identifying under what circumstances injuries are most likely to occur and then seeking to eliminate the sources or reduce the risks is always good practice. A study of video evidence of Norwegian professional football matches (a total of 174) where the match was stopped to deal with apparent injury led to 425 incidents being accounted for. Of these 121 acute injuries were reported. Interestingly only 52 of these were identifiable on video. This included all head injuries, 58% of knee injuries, and 56% of ankle injuries. Strikers were most susceptible to injury. No identifiable pattern leading to injury could be identified except that the player 'about to be injured' seemed to be unaware of the forthcoming incident (challenge). Being prepared for the encounter may, therefore, be a defence mechanism in itself.
An intervention strategy to prevent muscle strains based on the fact that muscle strains are common in high-speed sports and account for 10-40% of injuries in sports such as soccer, Australian Rules football, and American football is as follows:
A further paper may be seen as an example of this approach where the authors looked at identifying athletes at risk of hamstring strains and interventions to prevent them. Largely now understood to arise from eccentric contraction, it was found that hamstring injuries most commonly arose when repeated bouts of eccentric exercise were experienced without allowing for progressive adaptation. Microscopic damage inflicted on muscle fibres following a bout of unaccustomed exercise can lead to a strain especially if the angle of torque is acute - i.e. a greater level of contraction/probable flexion of the knee and/or hip. In the earlier stages of introducing new regimes, if repeat bouts of such activity are made after one week, then injury-free adaptation is more likely.
Further evidence is given in a paper that the remodelling (adaptation) following eccentric exercise may also be fibre-type specific. So the nature of the stimulus will impact on nature of the injury/adaptation so that also, the inflammatory response may exacerbate the situation in the early stages. This supports the initial proposal of a frequency of once weekly for a new training approach to not only avoid injury caused by the training itself but to best adapt the body to provide better concentric/eccentric muscle balance and the avoidance of injury related to that factor.
A Canadian paper looked at the relationship between the running injury and static lower limb alignment in 87 recreational runners and found no correlation between the two factors even though 79% of the runners suffered an injury of one form or another during the six months. The exception was a patellofemoral pain (under and around the kneecap) which did correlate with ankle dorsiflexion and another ankle/foot instability and bow-leggedness apparent at the knee. This seems to back up a previously reported review that indicated that hip rotator weakness was responsible for lower limb injury. Both articles, however, stress the importance of seeking advice on appropriate biomechanical assessment and injury cause consideration.
Looking further at recent papers proposing conditioning activities to avoid injury and improve performance one paper proposes a new computer-guided strength-training program to ensure that concentric and eccentric loads are appropriately matched in respect of their relative One Repetition Maximum (1RM) values. Working on knee extension with 18 males over four weeks, the results demonstrated increases in peak torque, muscle hypertrophy, and endurance. Of major interest, there was a strong indication that this form of training also facilitated a shift toward more type II fibre production and a stronger and faster muscle.
Another report looked at the effect of proprioceptive balance board training on the prevention of ankle sprains across a very large population of over 1000 male and female volleyball players throughout a whole season. Balance board trained players showed a lower incidence of ankle injury measured in injuries per 1000 total playing hours. However, this is only related to players with a history of ankle sprains. A possible contra-indication to this form of conditioning was found to be players with a history of knee injury since they showed an increase in overuse knee injury following balance board work. Looking at improving performance by applying knowledge gained through sports science studies is the real business.
A report out seems to meet this need when looking at the effects of weight only training versus combined training (weight and jump) on the impact of squat jump and countermovement jump in handball players aged 17 to 24. After a six-week training program, only those who had followed the combined training approach showed improvement in the height of the jump during the countermovement jump. Those who had trained with weights only and demonstrated an increase in maximal or explosive strength did not appear to improve their jump capability. The overall conclusions support the benefits of combined training whereby specific dynamic activities are performed in conjunction with strength development, to facilitate performance enhancement best.
Moving into the area of mental versus physical tiredness, a recent study used the Profile of Mood States (POMS) test to compare this relationship with the player position of rugby football players. In general, forwards showed a positive correlation between POMS scores and enzyme changes of musculoskeletal origin. Backs showed some similar traits but also showed a negative relationship between POMS and blood glucose levels for example. The conclusion was that different exercise loading of the position played during a rugby match may cause differences in the relationship between physical and mental fatigue and therefore could be taken into account in match preparation, strategy, and player selection.
Finally, this month, we take a look at the case for and against a multi-disciplinary sports science team behind a given performer or team. While the expected benefits of such support should by now be obvious, two recent papers[15,16] highlight the potential of working at cross-purpose and creating a highly undesirable conflict of interest. Furthermore, they point out that it is not possible to objectively monitor or attempt to control all aspects of a performer's lifestyle. On this front, the author contends that through a well-formulated training log, built-in feedback sessions, and a total empathy between coach and athlete and athlete and club/team the adoption of a lifestyle conducive to high performance is made easier. From this, I read that communication and understanding are not rocket science. However, communication needs to be at least two-way, and understanding needs to be checked!
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About the Author
Nigel Hetherington was 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 British Athletics level 4 performance coach in all events he has coached athletes to National and International honours in sprints, and hurdles as well as a World Record holder in the Paralympic shot. He has ten years of experience as a senior coach educator and assessor trainer on behalf of British Athletics. Nigel is also an experienced athlete in the 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 of experience in scientific research and publishing.