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Sports Nutrition and More at the 2008 AAESS Conference

Patria A Hume1 and Carl D Paton1,2

Sportscience 12, 25-30, 2008 (sportsci.org/2008/pahcdp.htm)
1 Institute of Sport and Recreation Research NZ, AUT University, Auckland 0627, New Zealand;  Email.  2 Eastern Institute of Technology, Hawkes Bay, New Zealand; Email.  Reviewer: Dr Johann Edge, Institute of Food Nutrition and Human Health, Massey University, Palmerston North, New Zealand; Email.

Future of sport sciences: exercise science and health vs sport performance. Exercise physiology: substrate availability, muscle spindles, vibration machines, field testing, high intensity interval training, compression garments, thermal exchange, pseudoephdrine, GPS. Nutrition: regulatory genes, amino acids, protein hydrolysates, caffeine, supplements.  Anthropometry: profiling, skinfolds reliability. Physical conditioning: kicking accuracy, YoYo test, performance analysis, jumps. Biomechanics and motor control: knee taping, injury prevention, knee joint load, isometric rowing strength test, cricket bowling, cycle crank arm length, musculoskeletal stifness. Basic science: responsiveness to training, muscle oxygenation.  KEYWORDS: elite athletes, injury prevention, training.

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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