Why do some athletes develop into accomplished middle distance runners, capable of running fast and winning races, while others get just a little better despite doing similar workouts throughout their careers? Also, most young seventh and eighth graders are about equal in distance running ability after their first season and usually only a few seconds separate runners of the same age, body size and skill level. Yet, following puberty and many seasons of training, a tremendous diversity exists in distance running skill despite similar body size. The reasons cannot be found just in athletic desire and determination differences among people. There must be detectable physiological reasons as well that are less obvious than general characteristics such as body size differences. Today we will discuss the trainability of the middle distance athlete.
Anyone who has ever trained middle distance runners will tell you that the rate at which a given individual within a group “becomes fit” or acquires new skills in response to training can vary dramatically. Trainability is the general term used to describe either the rate of change or the magnitude of change in fitness or skill acquisition in response to training.
An individual runner who shows rapid and most marked improvement to a given “dose” of training is said to be highly trainable. A slower responder or an individual who improves less over time is said to be less trainable. However, the rate of change to a training stimulus is not always uniform over time. So, an initial or fast response may not always be predictive of the total magnitude of the response after a period of months or longer.
* Coaching Resource: The Mile: Successful Coaching Strategies
In addition, because the duration of a vast majority of training studies is measured in months, it is not clear how years of training might influence ideas about trainability and responders. Many high school junior varsity runners go on and suddenly show dramatic improvement while in college. Trainability in many ways is unpredictable over the life of a long career.
It is also important to distinguish between trainability and natural (intrinsic) ability when analyzing middle distance runners and their potential. Some runners might enter a training program faster, stronger, or more skilled than others. However, high levels of natural or initial fitness are generally unrelated to the magnitude of change seen in response to standard middle distance training standards and stimuli. The initial skill seen in some beginning high school middle distance runners may just stem from a more active youth or perhaps many years of playing soccer. This will be unrelated to their trainability, specifically in the middle distance events.
n regard to the middle distance events, chiefly the 800 meter and 1500/1600 meters, it is important to recall the tremendous reliance on the aerobic energy system that is needed to successfully compete in these races. The ability to use a higher maximum amount of oxygen than the other competitors while at specific racing speeds has been shown to be a tremendous physiological advantage and usually separates the winners from the losers. With this in mind, and in the context of middle distance events, trainability must be defined as the increase in VO2 max in response to a specific training program.
VO2 max describes the maximum ability of a whole runner to transport oxygen from the air to the tissues and especially the exercising skeletal muscles. It is thus dependent on, and potentially limited by, numerous sites in the so-called O2 transport cascade.
This cascade includes the following:
1) pulmonary ventilation,
2) diffusion of oxygen across the pulmonary capillary membrane to the blood,
3) the bulk flux of O2 away from the lungs via a combination of cardiac output and arterial O2 content,
4) increased blood flow to contracting muscles, and
5) diffusion of O2 from blood to tissue and ultimately oxidative metabolism in the mitochondria.
Although each of the five factors previously outlined can influence VO2 max to a degree, if VO2 max is going to reach a peak two-fold increase due to chronic aerobic influenced training, then most of the gain will occur due to improved cardiac output and greater total body hemoglobin mass. The other factors only become potentially rate inhibiting in middle distance runners receiving chronic doses of aerobic training.
Data from a limited number of “sibling twins doing rigorous aerobic training” studies indicate that genetics does play a part in trainability. Most sets of twins experienced the same VO2 max increase with the same chronic aerobic training schedule. However, one contrary study on identical twins experiencing the same aerobic training each day produced data that showed an 18 ml/kg/min increase in one twin while the other showed a 29 ml/kg/min increase after 27 weeks of aerobic training.
Several observations challenge the idea that genetic factors are the major determinant of trainability in middle distance runners. First, none of the gene variants identified in twins studies are clearly linked to cardiac output, stroke volume, blood volume and red cell mass – the predominant physiological determinants of VO2 max. In addition, a survey of approximately 3000 elite male endurance athletes who regularly compete at the international level has identified no common gene variants associated with unusually high VO2 max values.
It seems reasonable to assume that these men’s training response is likely sufficient to generate maximum biological adaptations in their O2 transport systems rather than a gene variant being the major determinant of VO2 max improvement. This brings us back to the original question as to why some middle distance runners are more trainable than others.
* Additional Teaching Resource: The Training Model for High School Middle Distance
It is likely that genetics may play a small part, but not to the degree most coaches believe. The trainability difference is most likely in the day to day training stimulus. What may look like identical training in a group of runners probably isn’t. The most trainable of the runners do the quality work to the highest degree and frequently do a little extra. It does come down to effort of training as the biggest determinant of success.
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