It is often wondered how middle distance (800m) athletic performances utilise their energy expenditure and work distributed. This technique of training can be described as a “pacing strategy” according to sports physiologist Marino.
During middle distance performances, the human body uses different types of energy systems to maintain a high power output for the sustained duration. In order for this power demand to be met, the body will use a specific type of energy system depending on the length of the task. The muscles call upon an alternative process called the anaerobic glycogenolysis when performing middle distance activities. This entails the break down of stored carbohydrates in the muscles explains. However, fatigue prevents middle distance running performance. The buffering capacity and an increase in the acidosis within the cells for ATP resynthesis are only some of the many processes that cause fatigue. The null hypothesis is: Fast start and constant pacing strategies for 800m will not have an effect on performance.
The study investigated 25 participants through randomised selection (double blind) and conducted the three different pacing techniques on a weekly basis. Fitness levels of all athletes was moderate to extremely well active.
It is understood that exercise performance is the amount of work done over a given period of time. Therefore the body adapts to meet the physical demands need in order for an aesthetic and effective performance to occur. Many factors can effect this outcome, the duration of the event means that a different energy system will be used depending on the demands. In addition other factor will include type of event and the environment in which they are being performed. Sports scientists Maughan and Gleeson, state that shorter exercises uses more of an explosive “all out” strategy for performance lasting <30s. Where as in middle distance performances a more positive pacing strategy appears, meaning that after reaching a peak speed the performer slowly decreases until the task is complete. From our finding it is clear to see that this might be the case, as a significant difference was shown between the fast start pacing strategy compared to constant pacing for the full 800m. In addition there was also a significant difference between the fast start first lap (400m) than that of the constant pacing used. In the latter part of the task, the second lap showed no significant at all. Thompson et al. (2004) examined the effects of swimmers performing at 102% of there maximal and found they significantly slowed their pacing in the latter part of the event. The explain how there was evidence of high blood lactate levels and respiratory gaseous exchange ratios after the performance.
However many other factors affect fatigue, especially while dealing with middle distance performance and anaerobic glycogenolysis. Hormonal activity, oxygen availability and rate limiting enzymes (hexokinase, phosphoralase, phosphofructokinase and pyruvate kinase) in the anaerobic carbohydrate metabolism will have a major impact in pacing strategies determining the rate at which the muscles can break down glycogen and glucose into lactate. The location (muscles, liver, and blood glucose) and the amount of glycogen in the body will also influence this process. It is important to emphasise that the carbohydrate stores are the key function. So eating a more dominating carbohydrate diet will impact on the physiological metabolisms. In order to determine if there was a significant difference between the two pacing strategies and if the anaerobic glycoletic energy system was being used, maybe collecting blood samples form the participants after there performance to determine if there was a high blood lactate level would have made this experiment more reliable. Glycogen stores are replenished by blood glucose, and this usually takes approximately 24 hours. Showing that although this energy system is effective in the right environment and not too many factors, it can not be used multiple number of times, like during a game of soccer. It is ideal for middle distance athletic events and middle distance cycling events too.
This post was written and undertanken at the University of Chichester and carried out by Fitness Fan memberDane Michael