Archive for the ‘Sports science’ Category

Sleep and race better

Posted in Adventure racing, Kayaking, Multisport, Orienteering, Sports Science Interviews, Sports science, Trail running
Tuesday, September 7th, 2010

Clearly, anybody who has raced a 24 hour, 48 hour or expedition event will attest to the dramatic effect sleep deprivation has on performance and recovery.  The devastating effect that poor sleep has on health and well being was recently bought to the fore by the meltdown of players and coaches in the AFL who routinely take a plethora of legal uppers to get ready for night games and then prescription sedatives afterward to try and grasp somesleep. Getting the balance seems elusive.

 

Events to one side, quite often the juggling of exhaustive training loads with work, study and family comes at the cost of regular sleep.

 

Research over the past decade has looked to understand exactly what the metabolic and performance downsides are of disrupted and truncated sleep patterns.

 

Eve Van Cauter, Ph.D., (University of Chicago Medical School) in 1999, studied the effects of three different durations of sleep in 11 men ages 18 to 27. For the first three nights of the study, the men slept eight hours per night; for the next six nights, they slept four hours per night; for the last seven nights, they slept 12 hours per night.

 

Results showed that after four hours of sleep per night (the sleep deprivation period), they metabolized glucose least efficiently. Levels of the stress hormone cortisol (a by product also in abundance post heavy resistance exercise) were also higher during sleep deprivation periods.

 

This has been linked to memory impairment, age-related insulin resistance, and impaired recovery in athletes.

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Skill acquisition for the off-road athlete - go mental

Posted in Sports science, Training tips
Tuesday, August 3rd, 2010

illness.jpgBeing an effective off road endurance athlete requires you to develop efficient technique whether it be MTB cornering and rock hopping or a fluid paddling stroke;endurance, strength and agility are not enough.

Skill acquisition is a mental and physical challenge that requires a good deal of mental and emotional knowledge and understanding as prerequisites to practice and improvement. Investing the time and effort into improving the control of the mental and emotional elements in your discipline(s) elevates task performance and builds a psychological foundation for confidence and well-being (Boyd & Zenong, 1999).

Of the vast array of methods employed to evolve the necessary mental skills for task performance, the two most important are cognitive and somatic. As is the case with building your VO2 max and your core strength, the mental skills required for technique improvement require you to be motivated, set time to one side to learn and practice techniques and the commitment and self knowledge needed for goal setting.

Why bother improving your technical skills? What exactly motivates you to take on such a challenge? Is it a case of the extrinsic rewards you are pursuing in the sport such as the podium and or peer recognition? Or is it the desire for self-improvement; the intrinsic motivators?

Different researchers Weinberg (1984), Martens (1987) and Rushall (1992) have come up with the same common thread of findings that athletes should catalyse performance improvements from intrinsic rather than extrinsic motivation to reach their goals. Why? Extrinsic rewards by definition require control over many external variables; control that can be at best problematic and at worst, elusive.
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Join the Resistance Part II

Posted in Sports science, Training tips
Thursday, July 22nd, 2010


push-up-med-ball.jpgIt’s important to note that all of the test programmes and exercises cited in the preceding article did not involve sport specific movements. As such the link between endurance sports and resistance training is not clear cut. If we use a runner as an example with multiple joint actions and numerous muscle groups requires the various actions to work together to maintain control and balance where standard weight training only focus on a particular muscle group in a constant plane of motion. For example leg extensions will make ones quadriceps stronger however the strength gain is not specific to the way the quadriceps are activated while running and is not weight bearing. One could suggest this type of training is like coaching rugby players individually on their own position and without practicing together as a team expecting them to play in sync.

Resistance exercises aimed at improving running performance should not just attempt to increase general muscle strength; they should enhance specific activities of the nervous and muscular systems which promote faster, more coordinated movements (3).

While free weights are much more sport specific than machines integrated actions in medicine ball work, plyometric and kettlebell training can offer use for certain sports (8). It is also important that sport specific movements do not interfere with technique when the movements are similar but not identical (8) furthermore strength exercises of high force at low velocity do not provide benefits for sports requiring acceleration and vice-versa (8,2).

Plyometric Training

Plyometrics are any exercise that helps to develop the stretch shortening cycle of a muscle (4). They start with the stretching of a muscle, an amortisation phase (the period of time from the beginning of the lengthening phase to the beginning of the take-off phase) and then a muscle contraction phase (4). In this sense the faster the stretching phase, the faster the contraction phase. Such exercises can include jumping, bounding or throwing. During the early part of an athletes career the aforementioned exercises can be improved simply by increasing strength, however once maximal strength is reached one must increase their explosive strength or power to improve (4), hence the reason for plyometric training. One study in particular found that the greatest gains from plyometric training came from professional/elite athletes than amateur athletes (4). In this sense plyometric training should only typically be conducted after years of strength training, furthermore those highly trained athletes who failed to benefit from high resistance work should implement plyometric training.

 Kettlebell Training

 

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Join the Resistance - Part I

Posted in Adventure racing, Multisport, Sports science
Thursday, July 22nd, 2010


med-ball-lunge-home.jpgThe application of resistance training largely comes down to the individual. Do you to fit into the ectomorph slot (those with low muscle mass levels)? If so, you are going to be likely more suited to plyometric and strength based work, whereas if you fit into the mesomorph slot (those with high muscle mass levels) you may be more suited to postural/core and proprioception exercises.

Your work:life balance, access to facilities and resources as well as your budget and personality will influence how much and what type of resistance training is prescribed as will your age and resistance training experience.

Muscle Mass

Bigger, stronger muscles generate more forceful contractions which produce higher power and greater speed (1). However big muscles use more of our limited energy stores which is not compatible with the demands of endurance sport.

Other important findings to keep in mind when shaping a resistance training program:

  • High peak power – endurance races are typically performed at a constant speed and peak power often secondary is important as powering over short hills attacking quickly will make your race more successful (1). Excellent for races like the coast to coast run where direction and terrain changes constantly.

  • Lower relative muscular effort – Movements require a given force by the muscles, when your muscular strength is increased less of your maximal force is required to make the movement, increasing your muscular endurance (1).

  • Reduced injury risk – Stronger muscles are more capable of withstanding injury producing forces (1).

In effect, high muscle mass is useful in sports which are of shorter duration, require frequent intense bursts of power and where body weight is largely supported (1). For example a multisports race dominated by cycling and running will require limited strength, however if this race finishes with a technical and short kayak upper body and core strength training could provide an advantage. Interestingly some sports, particularly cycling will construct optimal power to weight ratios for climbers and power to height ratios for time trial specialists (1). Muscle mass is critical for performance of all endurance athletes however the importance is deciding how much time you will devote to it given your particular sport, event or individual physiology.

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VO2 MAX & interval training

Posted in Sports science, Training tips
Tuesday, July 6th, 2010


What is VO2max again?

The amount of oxygen(milliliters) you can use in one minute per kilo of body weight is the individuals VO2max or the highest rate of oxygen consumption attainable during maximal or exhaustive exercise(2). An athlete who is fit will have higher a VO2max than an untrained athlete at higher exercise intensities (3). As an athlete increases their exercise intensity their oxygen consumption increases until it reaches its maximum capacity. It is this point where VO2max is reached, however it is important to note that the exercise intensity can still increase however without further oxygen uptake (3). It is important to note that VO2max on its own is an inappropriate predictor of athletic performance (2,3) however it does provide a indication of athletic potential where lactate threshold will provide a better indication of athletic performance relative to the individuals ability (2).

Factors affecting VO2max

Genetic endowment contributes largely to ones VO2max due to the body’s ability to either utilize available oxygen or deliver oxygen to active tissues.

Utilization Theory

Maintains that VO2max is determined by the body’s ability to utilize the available oxygen. In effect, VO2max is limited by a lack of sufficient oxidative enzymes within the cell’s mitochondria (2).

Presentation Theory

Maintains that it’s the ability of the body’s cardio-vascular system to deliver oxygen to active tissues that is the key determinant, VO2max depends on increased blood volume, maximal cardiac output and better perfusion of blood into the muscles (2).

While both theories have their role in determining VO2max it is concluded that oxygen supply is the major influence in determining endurance performance as only weak relationships exist between oxidative enzymes and increase in VO2max (2).

Age

VO2max decreases with age, at an average rate of decline of 1% every year after age 25 and is typically attributed due to the effects of aging on the cardio-vascular system (2).

Intensive training during younger years does not offset this process, actually elite athletes have shown a more rapid decline (1.5% per year) once their careers are finished (2). This is not all doom and gloom, conversely master athletes show only minor loss (0.5-0.6% per year) while maintaining the same relative intensity of training (2).

Interval Length/Rate of Recovery and VO2max

vVO2max is the velocity at VO2max. When work intervals are conducted below vVO2max the total load on the cardio-vascular system can be directly related to the length of the work interval (1). On a study of work intervals over 30 seconds, 1 minute, 2 minutes, 3 minutes all carried out at moderately high but not high vVO2max intensities it was found that the shortest intervals produced sub maximal load on the circulatory and respiratory systems as well as low lactate levels (1). From this we must suggest intervals lower than vVO2max are more appropriate as the lactate production and elimination should be trained for longer endurance events and maximum speed at vVO2max is not as necessary as for a 5 kilometer runner.

In using the longer intervals VO2max will be attained in the first interval and subsequent recovery intervals will need less time to depress oxygen usage. Why? When moving at less than 90% vVO2max but above 90% of vVO2max it takes roughly two minutes.

From a practical point of view one should decrease work intervals during the session instead of increasing recovery interval as this will decrease average oxygen consumption rates and mean levels of lactate production effects which are counter productive in terms of VO2max and lactate threshold (1).

If VO2max or lactate threshold are unimportant and you only want to improve running economy the recovery to work ratio should be high(1) e.g. a 400m runner with little need for lactate threshold and aerobic capacity would have short work intervals and long recovery intervals to increase economy and speed.

Importance of vVO2max and Interval Progression

Long intervals can produce problems as they may display a false positive. Athletes with high vVO2 will be able to run quickly at VO2max, hence is fairly efficient making vVO2max a good indicator of performance (1). For example an athlete with excellent economy (running speed) may have a poor VO2max and is unable to reach high speeds at VO2max (1), a vital attribute for racing.

French researcher Veronique Billat has suggested the best way to convert interval training into performance increases is utilize vVO2max efforts in training to improve vVO2max, VO2max and lactate threshold and economy (1). While this training may cause lactate threshold to remain consistent the velocity at lactate threshold will increase due to improvements of vVO2max, furthermore training at vVO2max increases strength and power, strength boosts economy as when muscle fibers are stronger fewer are recruited to move at similar paces (1).

Ofcourse for the majority of athletes performing 3 minute intervals at vVO2max is not attainable from the get go; they need to build up to such an intensive session.

Billat suggests the use of 30 seconds at 100% vVO2max followed by 30 seconds at 50% of vVO2max. Interestingly even when the 30-30 is performed till exhaustion (when vVO2max cannot be sustained for 30 seconds) it is still less taxing than 5 x 3minutes at vVO2max (1). This 30-30 session can then progress to a 60-60 at which point one can begin training the classic 5 x 3 minutes at vVO2max.

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Bouncing back

Posted in Sports science, Training tips
Thursday, March 18th, 2010

Trained for 12 months, overcome injuries and illnesses fronted for the big race and fallen well short of your ambitions?

It feels anywhere from disappointing to devastating doesn’t it? Failure can be due to a poor judgment call whether it be a technique breakdown under pressure, poor choice of nutrition on the day or a tactical misread of pace; there are many nuances of implementing your race plan that may bring you undone. Failure may also simply be due to falling short, despite every preparation and every effort on race day; you simply do not get the time or place you had worked for; this hurts, yet this type of failure should scream to you that you are just a step away from succeeding.

Deciding what effect failure has on you is entirely in your hands. So, what do you do to bounce back?

Keeping a perspective

As corny and cliche as it may sound, the path you took to the start line is what should allow you to draw strength; it is the preparation, the application, the problem solving and persistence that you have acquired in getting ready to race that will have underpinned your physical and mental reserves you can now draw upon.

You have experienced a setback; not a failure, so get it through your head and repeat it in front of the mirror. You have been knocked back, not knocked down. Has anybody died as a result of you not landing a PB or a medal? Probably not; so keep it in perspective.

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It’s HOT… get used to it

Posted in Sports science, Training tips
Wednesday, January 14th, 2009

heat-exhaust.jpgOK it’s that time of year again Down Under when it’s dangerous just walking in the sun let alone ripping into a multi-sport event or trail race. It’s important to sensibly manage any ventures in the heat and ensure you acclimatise first.

Acclimatization is the physiologic and psychological adjustment to a new environment different to that which you live in.

Some of the physiologic adaptations that occur as part of heat acclimatization include: reduced heart rate, core temperature, and utilization of muscle glycogen, as well as increased blood flow to the skin, plasma volume, and work time until exhaustion. Well-conditioned athletes have a higher heat tolerance than sedentary people, as regular exercise creates “internal heat stress” and thus pre-acclimatizes athletes to some degree.

Heat acclimatization usually takes 10 to 14 days, although 75% of the adaptations are believed to occur within the first five days. Exercise sessions during the acclimatization process should be shorter and less intense, gradually building up to normal by the end of the two week period.

It is the process by which the body makes physical adaptations to better respond to physical activity in the heat. It occurs only after repeated bouts of heat stress from training that is sufficient to increase core body temperature and produce a significant amount of sweat.

Heat acclimatization has a number of benefits. You feel more comfortable at a given pace while racing in the heat. Your core body temperature and heart rate for a given training intensity will be lower. The onset of sweating and the amount of sweat produced increases,  improving heat transfer, but the electrolyte concentration of sweat decreases.

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