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The 2008
conference of the Australian
Association for Exercise and Sports Science (AAESS), this year held in
Melbourne Australia March 27-30, was a combination of three keynote
addresses, a special lecture, 31 invited addresses and symposia presented by
~60 people, 91 podium and 38 poster presentations. There were over
500 international and domestic delegates, which the conference
organizers estimated to be 15% sports dieticians, 40% sport scientists,
and 45% exercise physiologists.
With the theme “From Research to Practice”,
the conference aimed to make findings relevant to the practitioner and
included several workshops. The conference linked with Sports
Dieticians Australia for a major focus on nutrition for sport and exercise. Overall
it was clear there has been a shift towards exercise science and health rather
than sport performance, as evidenced by the number of presentations in the
chronic illness areas (such as obesity, cancer, osteoarthritis), and also
from the number of sport scientists who are now researching health aspects of
exercise. Be that as it may, we have limited this report to
presentations dealing with factors affecting athletic performance. Here is a
summary of the key points:
•
Blood samples on individual
athletes should be taken to determine when
their caffeine peaks, as there is variation between one hour and two
hours in peak caffeine for well-trained cyclists when using 6 mg/kg caffeine
for sprint performance (Ben Desbrow).
•
Bike set-up needs to be
individualized using optimal cadence and crank length (Cameron Christiansen).
•
Vitamin C supplementation
probably impairs endurance training
(John Hawley).
•
Isometric rowing-specific
strength assessment is more useful at predicting rowing performance than 1RM
squats (Mark Osbourne).
•
Pseudoephedrine (no longer a
banned substance) appears to offer some performance enhancing effect for
endurance athletes (Scott Beteridge).
•
Compression garments do not
appear to improve physiological markers of recovery after short-term sprint
and plyometric exercise, but they make the athletes feel better (Rob
Duffield).
•
High-intensity training when
performed in a partially carbohydrate-depleted state leads to beneficial
adaptations in fat metabolism (but not necessarily performance) with
endurance athletes (John Hawley).
•
High-intensity interval training
improves rowing performance better than traditional training (Matthew
Driller).
Forum:
Future of Sport Sciences
A panel
comprised of Ross Smith, Steve Bannon, Jen Bangsbo, and Bruce Elliot
answering questions from facilitator Mark Osbourne and from the audience. The first question related to whether technical
advances in sport assisted with behavior change or performance. Main
points of discussion included that the current focus seems to be on
developing skill
acquisition, scientists need to work more collaboratively to have
clear answers to coaches’ questions, there is a need to show that sport
science actually makes a difference, and coaches need to be part of,
and endorse research. Performance optimization needs to be the
goal of research. Linking sport research with injury issues
can help gain research money; otherwise you need specific research committees
for sport. PhD-level financial support for sport research
is a real issue. There needs to be a contribution along the
way to performance in sport, with prioritizing of research by sports. There are issues regarding confidentiality of information
and a lack of information sharing. There needs to be funding for long-term
projects that can make a difference rather than the current emphasis on showing
short-term gains. More identification of talent in sport science researchers
is needed. Panel members noted that pressure for
academics to gain research funding has led to research in exercise science
and health rather than elite sport (which has limited funding outside of
research at Australian sports institutes). There needs to be a combination of health promotion and sport, not
just an elite sport focus, if sport research institutes are to survive; for
example, soccer performance in middle-aged men with a health emphasis should
be just as important as elite soccer performance.
Exercise Physiology
John Hawley
presented an overview of the role of substrate availability to modify
training adaptations. Training with low muscle glycogen levels may
enhance adaptations to training.
It was recommended that for the train-low compete-high (glycogen) strategy,
about half the time should be spent training on low glycogen. High-fat
diets can help force muscle to use fat as the main fuel, then you
can consume carbohydrate to super-compensate. There can be increased fat oxidation and
sparing of muscle glycogen using this approach.
Supplementing with amino acids may stimulate mTOR, which leads
to increased skeletal muscle growth. Vitamin C supplementation may reduce the
effects of endurance training by limiting the growth of mitochondria in
muscle.
Uwe Proske (Monash
University) outlined
the basic anatomy and function of muscle spindles in relation to disturbed proprioception after exercise and the role in sports injuries. Muscle spindles have two different roles: to
provide signals for the sense of position and movement (conscious) and to
provide input to motor neurons as part of the stretch reflex (unconscious). Muscle
spindles are sensitive to errors in limb position history and also respond to
contraction of muscle intrafusal fibers.
Fatigue of the muscle results in disturbed position sense. A 20% decrease in force will lead to an
approximate 3º knee-flexion error. A fatigued quadriceps may lead to increased
stride length, which may then result in increased risk of hamstrings injury. Whether
the brain can recalibrate to a new position is unknown, and whether there is
a change in proprioception with hypertrophy is unknown.
Force
sense is disturbed by pain but position sense is not. Vibration
machines drive muscle spindles, but when the vibration stops the
discharge levels also drop for the spindles.
Jens Bansbo (University of Copenhagen) gave a thorough presentation on
the testing and training of elite intermittent sport (mainly soccer)
athletes. The presentation included a discussion on
the merits of various laboratory based physiological assessments
compared with the practicality of field based performance testing, which Jens
believes often yields more valuable insights into player ability. He offered
a rationale for the different types of training undertaken by
intermittent sport athletes by linking the training with functional
physiological changes in the central and peripheral systems of the body.
Carl
Paton chaired a session which included presentations from Knut Schneiker, Rob
Duffield, Aaron Coutts, Kylie Hunter, and Stephen Hill-Haas. Both Knut and Stephen (in separate studies)
looked at the athlete
response to different types of training (high intensity interval,
repeated sprint and small-sided game) on the physiology and performance of
team sport athletes. Not
surprisingly high-intensity
interval training led to substantial improvements in muscle buffer
capacity and performance.
Similarly sprint training led to improved sprint performance. Stephen’s results showed that small-sided games
training was just as effective as aerobic-type interval training for
improving aerobic fitness (in the yo-yo test) during pre-season training. You
should also periodize training to suit the particular needs of individual
athletes. Rob Duffield gave an
excellent presentation on the failure of compression garments (the current must-have
amongst athletes of all abilities) to improve markers of recovery following
high-intensity training; however athletes perceived
that they recovered better (placebo effect?).
In one of the more interesting presentations, Kylie Hunter reported that a
hand-held rapid thermal exchange device led to significant
reductions in core temperature and enhanced performance in cyclists exercising
under extreme thermal conditions.
Such devices may provide useful advantages to team sport athletes when used
in the break periods of games.
In a cycling
session Carl Paton presented a study showing that moving the cleat
position on cycling shoes did not lead to any substantial
physiological or performance benefits with well-trained cyclists. In a similar vein Jack Burns reported that
training with a commercially available system (PowerCranks) for five weeks
did not improve cycling economy and efficiency or maximum oxygen consumption
with moderately well-trained riders.
In a well controlled study Will Bradley and colleagues showed that in the
presence of adequate cooling (provided by high wind-speed fans)
prior dehydration resulting in up to 3% body weight loss did not impair 25-km
cycling performance despite a significant rise in core body temperature. Scott Beteridge and his colleagues from Massey
University presented research suggesting that pseudoephdrine use may lead to
worthwhile (but not significant) improvements in performance in endurance
cycling events. The results of this study are interesting and show good gains
in most of the athletes but also quite large negative effects (possibly due
to overheating) in a few of the athletes – hence no “significant changes”,
owing to individual responses.
John
Hawley’s PhD student Wee Kian Yoo gave an excellent presentation on the
effects of 3 wk of high-intensity training in either a high or low carbohydrate
state on cycling time-trial performance.
Evidently athletes self select a lower training intensity in the
carbohydrate-depleted state, but this does not attenuate long term
performance adaptations; indeed it appears that training in the carbohydrate-depleted
state may lead to favorable fat utilization.
Andrew Townshend reported that recent improvements in the accuracy of cheaper
non differential GPS may prove useful for monitoring athletes
in longer distance running events.
The best
poster presentation award went to New Zealander and current Tasmania PhD
student Mathew Driller for his research on the effects of high-intensity
interval training in rowers.
Matt’s research adds to the growing literature supporting the benefits of high-intensity
training for enhancing endurance performance.
Nutrition
David
Cameron-Smith presented an outline of signaling pathways and how muscle
grows, repairs and adapts via regulatory genes. The role of amino acids and glucose in
stimulating growth and recovery via insulin-stimulated protein resynthesis is
particularly important for strength athletes. Branched-chain amino acids go straight
through the liver (unlike other amino acids) to the muscle, and whey protein
is a good source. You need to eat protein before and after
exercise to ensure a positive balance of protein.
In the
sports physiology and nutrition session Jonathan Buckley showed that some protein
hydrolysates accelerate repair of damaged connective tissue. A comparison
of 25 g Natraboost and 25 g whey protein showed improvements in knee extensor
torque. There was complete recovery after six hours
with the hydrolysate.
Ben
Desbrow from the Australian Institute of Sport tested the effects of
Coke-Cola on endurance performance. A number of different drink compositions
have been studied using a cycling protocol of a 2-h steady ride followed by a
30-min time trial. For example, the effects of caffeine
(6 mg/kg total) ingested pre-exercise and at 80, 100 and 120 minutes showed a
3.3% increase in time-trial speed. There
were no effects on performance for different drink flavors or sweetness. Their
studies show marked individual differences in response to
caffeine: a fast responder peaked at 1 h post-ingestion while a slow
responder peaked at 2 h.
Stephen Bird gave a keynote on the role of supplementation strategies
to optimize performance. Key points: a combination of
carbohydrate and protein is more effective in the recovery of glycogen than
carbohydrate alone, and amino-acid supplements may be more important than
protein for recovery after exercise. A summary of his presentation is in press
in Journal of Strength and Conditioning
Research.
Susie Burrell continued the keynote from a practical perspective noting
that there is extreme protein supplementation occurring (>300 g/day) in
athletes, while there is often low carbohydrate (<100 g/day). There is
a failure to fuel pre, during and post with weight training sessions. There is
an over reliance on simple sugars for energy, and a low intake of unsaturated
fat. In Australian swimmers 87% are using supplements,
and in Canadian swimmers 80% are using supplements.
There is no evidence for glutamine enhancing performance, but some anecdotal
evidence from the AIS for recovery for hypertrophy. Olive oil and omega-3 fats have anti-inflammatory
effects, so they should be included for recovery in some form.
Anthropometry
Gary
Slater (Australian Institute of Sport) showed how he used data from the
Sydney Olympics anthropometric profiling
project as a guide for selecting rowers who had been rowing as heavy weights,
but based on the anthropometrics were more suited to being light-weight
rowers.
Although they could get athletes to drop 2-3 kg one week out from
competition, the main issue was for rowers to be able to sustain the
light-weight training program of reduced calories and high rowing mileage. Gary’s
studies have shown that there is a mean increase of ~8 s (~1.5%) in race time per kg of extra fat.
Gary Slater
also presented an overview of the main questions asked of a nutritionist when
an athlete needs to increase their muscle mass: How much should energy intake
be? Where should the energy come from?
When should energy be ingested over the day?
While he didn’t answer these questions, he did claim that it is easier
to increase lean muscle mass and allow the skinfolds to increase when trying
to get an athlete to increase lean muscle mass.
The
sports nutrition/anthropometry stream included Patria’s paper on reliability
of skinfold measurements. The key point of the presentation was that
you need to identify
the skinfold sites using anatomical landmarks, otherwise the
reliability of repeated measures is poor, and will not allow good estimation
of body composition changes with training interventions.
Andrea Braakhuis presented some of her PhD work and reported that diet
influences non-enzymatic but not enzymatic antioxidants in rowers.
Physical
Conditioning
Warren
Young presented the acute effects of 10 min of football exercise on kicking
accuracy (to a large projected bulls-eye on a screen) in elite
Australian Rules football players. However the exercise apparently was not
stressful enough. Anthony Leicht reported large differences
between air- and mechanical-braked cycle ergometers in the assessment of
anaerobic power and capacity. Robin Callister reported few differences
between the YoYo
and multistage
fitness tests, but the YoYo test provides a useful measure of
fatigue. David Buttifant reported decreased acute
traumatic injuries with increased AFL football player
rotations/replacements when looking at injury information from 2005, 2006 and
2007 seasons, even though the speed of players (using GPS tracking of eight
Collingwood players) has increased by approximately 1.5%
each year.
Robert
Newton (Edith Cowan University) presented a workshop outlining performance
analysis needs, including initial testing, training-program
design, implementation of the program, frequent assessment, and education of
the coach athlete and scientist.
He discussed a wide range of tests:
•
Maximal strength is
assessed preferably via 1RM squat or via prediction from 6-10RM.
•
Maximum rate of force development is a good measure but needs lots of practice for it to be a valid
test.
•
Loaded jump squats are
good for assessing power of the leg extensors. Force and bar kinematics should be
measured, including height, velocity, force and power output. Use a
concentric spectrum at 30, 60, 80% 1RM and determine the optimal load for
power production. Use loads of 30-40%
1RM to determine technique. There
are large errors in estimating load if you do not include body weight during
the jump squat. Standardize the
jump with no load using the shaft of a kayak paddle.
•
In the drop jump instructions are
critical and should be “jump as high as you can but with the shortest contact
time”. Use 30, 45, 60, 75 cm drop
heights, depending on athlete height. Reactive strength is useful: the better
trained, the higher the drop height and the better the reactive strength. With better
training there will be a shift in the optimal drop-jump height.
•
Repeat jumps should be
used for power endurance (peak velocity, power output, total work done,
fatigue). Skiers use a box test for 90 s jumping on
and off the box side to side.
•
Contact time should be
measured using a run onto a force plate. Instantaneous feedback is important and can
be provided by beeps indicating when the athlete is hitting the times.
•
Athlete-powered treadmills can be used to measure force, power, acceleration development
and repeated sprint. There are
four force transducers on the treadmill and the athlete is tethered to a
strain gauge. This test is useful where horizontal leg
thrust is important.
•
GPS speed profiles can
provide instantaneous velocity through a 50-m sprint.
•
Reactive agility
testing requires an athlete to respond to an arrow and change direction. This type
of test is useful for netball, where a screen shows a netball player passing
a ball and the player has to respond.
•
Musculotendonous stiffness is trainable and can be used as a diagnostic tool, but more research
is needed.
Information
dissemination is now faster, with athletes having lap tops and using web
systems. The future is on-line data collection. Field monitoring and web-based report and support
are developing. Strength and
conditioning specialists should be seen as the performance engineer (e.g.,
like mechanics at Formula 1 car races).
Biomechanics
and Motor Control
Patria
Hume chaired a session on lower limb biomechanics. Alasdair Dempsey (University of Western
Australia) showed that knee taping may decrease knee
moments. Damien O’Meara showed
unsurprisingly that video game induced soccer kicking performance produced
less muscle activation than real soccer kicking.
Bruce Elliott (University of Western Australia) summarized the use
of biomechanics for performance optimization and injury reduction, while
highlighting the current shift of biomechanics to clinical biomechanics to
improve movement following disease, driven by limited funding for sport
research. Sport performance biomechanics
must have sport validity by addressing the questions of interest to coaches
and players. Steps include identifying critical features,
such as 40% of shoulder internal rotation is needed for a tennis serve; publishing
findings in journals, so that there can be academic critique of
findings, and presenting research to practitioners and in popular media, such
as Women’s Weekly. Injury
prevention biomechanics research
has five steps: establishing the need for the research using valid
epidemiological data (extent, nature, severity); identifying the cause of the
problem; developing prevention strategies; educating the relevant population;
and evaluating the effectiveness of preventive measures.
Focus is usually on the most prevalent of the most debilitating injuries; for
example shoulder alignment greater than 30º with respect to the hips results
in increased risk of back injury. Education alone did not work with Australia
Cricket; rather, an individualized approach was needed.
To highlight the injury prevention research model football knee injury was
reported. The epidemiology and
etiology shows that varus and valgus rotation are critical factors. Unanticipated movements increase joint loading
two times normal. Greater loading
occurs with defending. Studies have shown that with balance
training there is a decrease in valgus and varus loading. The injury prevention strategies were designed
to decrease trunk lateral flexion and to decrease the lateral placement of the
foot with respect to the midline.
There was education and a randomized control trial with balance and agility
training and lab tests and field tests.
Alasdair Dempsey’s research showed that decreased knee joint load could occur
through technique modification.
Marcus Lees’s reported the role of perception in decreasing loading in the
knee (using 3D goggles and video training). Jon Donnelly’s research showed that upper
body control resulted in decreased risk of ACL injury. Bruce emphasized that the key to good
sports biomechanics research is to ask good questions.
Mark
Osbourne (Queensland Academy of Sport) works predominately with rowing and
mountain biking as the physiologist. Mark presented the Australian Rowing new isometric
rowing strength test that has been developed as a series of
rowing-specific static positions on an ergometer with force output. Force
peaks around 50-60% of stroke length. A scaling coefficient of 0.66 was used for maximal strength to allow
comparisons between light-weight and heavy-weight rowers and between males
and females. The testing at the position two-thirds
through the stroke correlated well with 2000-m ergometer rowing time (r=0.87), whereas a squat 1RM had a lower correlation
(r=0.72) to ergometer time. Isometric
rowing-specific testing is a reliable way of determining strength benchmarks
for rowing.
In the
sports biomechanics session Rene
Ferdinands presented his cricket work on forward solution questions to
address the shoulder-hip
alignment issue. Forces and torques are used to drive the
model to predict the best changes for an individual cricketer. Dean
McNamara showed upper body alignments during fast bowling. Inter-acromium markers did not accurately
present thoracic movements for mixed action. Scapula movement caused a change in the
acromium, which explained why there was not a good representation of thoracic
movement.
Cameron
Christiansen showed work to predict the optimal crank arm length for cycling. Crank arm
length is usually set as 20% of leg length, but crank arm length
is affected by cadence or task.
Cameron suggested a design for an adjustable crank arm that could change
length depending on the terrain; for example, more power is needed for a hill
climb. A cyclist with long legs wants a slow cadence
to decrease inertia, so bike set-up needs to be individualized using optimal
cadence and crank length. Small moments or tendon stiffness can be
used to predict crank length and cadence. Corey Joseph assessed the linearity of musculoskeletal
stiffness during running and jumping tasks. There was increased stiffness with
eccentric actions and landing, and a decreased stiffness with concentric
action. A full body model should be used when calculating
limb stiffness.
Basic science
In a
presentation on methodological design for assessing adaptation to resistance
training, John Sampson recommended randomizing to balance groups on responsiveness
to training rather than on 1RM. At least two weeks of training is required
to quantify responsiveness before allocating subjects to training and control
intervention groups.
Johan
Edge suggested that acidosis may interfere with training-induced metabolic
adaptations. Future research aims
to asses if any advantage is to be gained by promoting metabolic alkalosis
via appropriate supplementation.
Graham Lamb and Michael Mckenna teamed up to give an engaging presentation on
muscle fatigue. Graham presented
information from many single fiber muscle studies on the possible causes of
muscle fatigue in various situations.
Michael then completed the presentation by relating the potential mechanisms
to the intact human. David Bishop investigated the physiological
reasons for task failure (fatigue) during high intensity cycling and reported
that the most likely reason for fatigue is a reduction in muscle
oxygenation and not a failure of the central nervous system.
Acknowledgements: Patria thanks the Faculty of Health and
Environmental Sciences sabbatical fund of AUT University,
and Sport and Recreation New Zealand for funding to attend the conference. Patria
also thanks the Australian
Catholic University
for providing accommodation during the conference. Carl is grateful to the Eastern Institute
of Technology for funding to attend the conference.
Published Aug 2008.
©2008
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