What the experts say
Nigel Hetherington reviews the latest research material relating to coaching, exercise physiology and athletic development.
We are always in search of absolute measurements of the potential of an athlete to perform. In the case of ultra marathon distance runners, researchers in Japan may have found the answer. A total of 247 male participants in a 100km event were monitored using echocardiography. Correlations between age, body surface area, monthly running distances, echocardiographic variables and the actual race times were examined. Multiple regression analysis of the data demonstrated that age, monthly running distance and the left ventricular diameter were significant predictors of performance. Bigger heart, better runner .
The interval endurance capacity, IEC, is the ability to perform high-intensity activities like running and sprinting, as well as the ability to recover well during low-intensity activities such as walking and jogging. IEC was the subject of a study in both elite and sub-elite field hockey players over a three-year period. The study found that when the youth players were on average fourteen years old, differences in IEC scores were not significant yet between elite and sub-elite players. One year later, there was a trend that elite players outscored the sub-elite players on their IEC, but again differences were not significant. Two years later, at an average age of sixteen years, differences were significant, favouring the elite players. Even after considering the effect of percentage body fat, additional training hours, and motivation, the remaining differences between individual players are considerable.
Before and immediately after the 2004 Ironman Triathlon ambient temperature, % relative humidity, body mass, plasma concentrations of sodium, potassium and chloride ions and urine specific gravity were measured in 10 well-trained triathletes. Core temperature was measured intermittently during the event using an ingestible pill telemetry system, and heart rate was measured throughout. Mean performance time was 611 minutes; heart rate was 143bpm (83% of HRmax) and core temperature was 38.1°C. Body mass significantly declined during the race by 2.3 kg whereas urine specific gravity significantly increased (1.011 to 1.0170 g/ml) and plasma sodium, potassium and chloride ion concentrations did not change. Changes in body mass were not related to finishing core temperature, plasma sodium or urine specific gravity. In contrast with previous laboratory-based studies examining the influence of hypohydration on performance, a body mass loss of up to 3% was found to be tolerated by well-trained triathletes during an Ironman competition in warm conditions without any evidence of thermoregulatory failure.
Hydration has also been the subject of a study in tennis, where, following a substantial practical review a series of conclusions were made: " Maintaining appropriate fluid levels is vital for performance and temperature regulation. Tennis players need to be on a structured fluid intake program during practice and match sessions.
A series of papers on training for power, speed, anaerobic capacity and the effects of recovery and stretching also came to light this month. In the first the authors looked at power output and heart rate during repeated bouts of rowing with different recovery periods of 1.5, 3 or 6-minutes. Nine male junior rowers performed two all-out bouts of 1000m rowing on an ergometer on three separate occasions in a random order with respect to recoveries between the two repetitions. The conclusion was that with performance times in the region of 209s and power output of the order of 313W recovery of mean power output was incomplete even after 6 minutes suggesting that to achieve certain aims the recovery period needed to be greater than 6 minutes.
The purpose of the second study was to identify the effect of 4 months of different training modalities on power, speed, skill and anaerobic capacity in 15-16 year old male basketball players. 35 basketball players were randomly assigned into three groups: power endurance (intermittent exercise, PE), general endurance (continuous exercise, GE) and a control (regular basketball training, CG). The training models were used for 16 weeks in sessions conducted 3 times a week for 90 minutes each in the competition period. The following tests were performed: 20m speed run, squat jump, countermovement jump, running-based anaerobic sprint test (RAST), 2 min. shooting test and the shuttle ball-dribbling test. No statistically significant differences in the 20m-speed run, squat jump and countermovement jump were observed. On the other hand, RAST showed significant increases in PE, with greater increases during the 5th and 6th runs. The PE training model also produced a significant improvement in the shuttle ball-dribbling test (falling from 48.7 to 45.5). The results suggested that both training modalities were able to maintain initial values of speed and power, however, the anaerobic capacity and skill increased only in the players from the power endurance group. Therefore, the power endurance training (intermittent high intensity exercise) may be more beneficial to prepare junior players according to the game cardiovascular and metabolic specific determinants.
A further paper looked at active versus passive recoveries in climbers who completed five two-minute climbing trials before a two-minute recovery period followed by a one and half minute passive refocusing period for all climbers before the next trial. There was a significant difference between active and passive recovery conditions in terms of lactate concentration and Rating of Perceived Exertion RPE with both measures being lower across all five climbing trials for the active recovery protocol. After active recovery climbers started the next trial with a lower arterial lactate concentration than for a passive recovery and indicated lower RPE scores at the end of each climb. The refocusing period following active recovery allowed climbers heart rates to return to a lower level at the start of the next climb than for the passive recovery condition.
On a technical point a study highlighted the importance of equipment and experiment design in terms of reliability of results. The study determined levels of muscle activation in the hamstring and quadriceps groups of muscles in triathletes during the cycling phase and the effect on this of bicycle seat tube angle (STA). The STA is defined as the position of the seat relative to the crank axis, the pedal shaft and the canter axis of rotation for the front gears, of the bicycle. The typical range in STA for a road bike is between 70° to 76°. This position places the rider in a posture more similar to sitting in a chair with the hips behind the feet and crank axis. A triathlon bike usually has a steeper geometry with a STA greater than 76°. The steeper STA places the rider in a posture more similar to running with the hips over the feet and crank axis. This particular study identified that when the STA was increased to 82° triathletes were able to maintain power production while significantly reducing hamstring activation (by about one third).
Various studies have reported on the loss of power output through static stretching prior to activity but a study looked at the possible impact of prolonged stretch training to increase the range of movement to establish if this was a factor. In other words, could it be that just those athletes who have poor flexibility are prone to stretch-induced deficits. The findings were quite conclusive in that the pre-existing ROM of the performer bears no relation to the deficit to power caused by static stretching immediately prior to activity and power loss in these circumstances is universally measurable factor.
Participation in sport has many benefits and so it was refreshing to read a study from the Netherlands that had analysed a large volume of data to establish what relationship exists between levels of physical activity and sick leave. Moderate levels of activity did not appear to correlate. However, for those involved in activity at least three times per week significantly less sick leave to the extent of more than 4-days per annum. Interestingly the duration of vigorous activity did not correlate with sick leave. Sounds like three short-sharp bursts of activity each week are all that is required to keep you healthy!
Increasingly athletes are turning to physiotherapists rather than their General Practitioner / Physician for diagnosis and treatment of musculo-skeletal injury and in supporting rehabilitation. A recent study examined to what extent (if at all) the Physiotherapist, in this situation, is responsible for the psychological wellbeing of the patient. A conclusion stated that 'the major psychological issues for physiotherapists in facilitating injury rehabilitation are communication, motivation and encouragement'. A deeper conclusion stated: 'the role of the physiotherapist in facilitating athletes' recovery from injury is, without question, pivotal. An intuitive understanding of psychological principles often underpins the treatment approaches adopted by physiotherapists. The athlete who has physically recovered from injury but remains psychologically unprepared to compete is not fully recovered.'
Finally this month, and I do not have it in for footballers, a study examined the presence of biochemical markers of brain tissue damage in footballers based on an analysis of activities within a competitive game. Interestingly there was a clear correlation between the presence of such markers from brain tissue damage and the number of headers completed - hence the quaint expression used to describe someone who may not be quite all there: 'he's a head the ball!'
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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, 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 British Athletics. 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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