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