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PHYSIOLOGY AND FITNESS
Physiology is the study of the body’s natural processes. Such processes include metabolic processes. Metabolic processes deal with the chemical reactions that happen in the body’s cells. From understanding such physiological factors of a specific athlete, trainers can more accurately acknowledge the athlete’s fitness. Trainers can, then, recognize unique needs of this athlete. Such needs may be nutritional supplements, method of training, and amount of rehydration.
[Metabolic Processes]
[Negative Biological Reactions in Tedious Situations]
[Evolution in Traits Dominantly Used With Growth]
[Rehydration and Supplement Intake of Juniors]
Metabolic processes are chemical reactions that happen in the body’s cells. These chemical reactions are essential to generating energy for use. Chemical potential energy from food intake is converted into kinetic energy to fuel muscle movement. A tennis player needs to use an immense amount of energy in order to sustain their performance in each match of every tournament. Matches can last up to two hours. The winner of a grand slam tournament would have normally had endured seven competitive matches over a two-week duration. An athlete’s capability of energy production through metabolic processes is evidently crucial part of his or her physiology fitness. An understanding of the principles of metabolic processes will allow trainers to create a fitness program suitable for the individual athlete.
Unfortunately, an understanding of metabolic processes during actual competition is poorly defined, even among scientists. For example, several published experiments from the past reveal data discrepancies about sources of energy production. M.A. Christmas, S.E. Richmond, N.T. Cable and P.E. Hartmann have addressed that experimental errors likely resulted from indirect methods of measurement of metabolic processes, such as heart rate, rather than incorporating bodily fluid examination. To refine our comprehension of energy production in metabolic processes, Christmas, Richmond, Cable and Hartmann presented their own laboratory report at the First World Congress on Science and Racket Sports in 1993. (Hughes, Lees, Reilly; 1995)
Christmas, Richmond, Cable and Hartman’s laboratory report was titled “A metabolic characterization of singles tennis”. During the experiment, eight volunteer male Australian state league players’ fitness, match conditions, activity intensity and metabolite concentration were accounted for. Players played 90 minutes in a competitive match. Fitness was measured by:
- maximum aerobic power- the power exerted by muscles when operating under aerobic respiration. Aerobic respiration of the muscles occurs when muscles utilize oxygen to produce energy.
- maximum heart rate- the fastest heart rate that an individual will experience. This is roughly determined by subtracting an individual's age from 220.
- maximum power index
- alactic work capacity index
- anaerobic work capacity index
- acliposity- body fat content
- proportional weight rating.
Match conditions consisted of
- the work and recovery proportion- a ratio between the time that the tennis players were actually playing and the time that the tennis players were not actually in a rally
The intensity of activity was measured in terms of:
- the proportion of the average heart rate to the maximum heart rate
- the oxygen intake compared to maximum aerobic power
- steps taken per second
Metabolites are chemicals produced during metabolic processes of energy production. The concentration of the following metabolites were examined:
- lactate
- glucose
- glycogen
- beta hydroxybutarate
The data of the results in the players’ fitness was similar. This was due to the similar level of training that players would have undergone throughout their career. The match conditions were also similar, as the work and recovery time proportions were similar. The activity intensity data was deemed as the most crucial information not obtained from bodily liquids. This was because the intensity of activity causes the levels of energy conversion and energy consumption. The activity intensity results were extremely close. The controlled level of skill amongst the players, again, could explain this.
As this experiment attempted to more directly study metabolic processes, metabolites were extracted from the blood of the players, throughout the 90-minute matches. To ensure minimal interference with players’ physical states, blood was obtained by pricing a finger of the non-dominant hand. A controlled set of data was obtained from finger prick before the athletes warmed up. Afterwards, the athletes’ fingers were pricked every odd game. (Hughes et al., 1995) Results showed a great difference in lactate production levels between the experiment’s subjects and past experiments’ data. It was also surprisingly not at all proportional to the oxygen intake data, under activity intensity. This was surprising because muscles produce lactate after repetitive contractions. Christmas, Richmond, Cable and Hartman concluded that the great variations might have been due to differing playing styles, environments and psychological strength. The data that was relative to lactate production levels was glucose production, implying their relation to each other’s production. This is because as muscles decrease respiration during recovery was it is a natural process of the human body to undergo a process that converts lactate to glucose, especially under intense activity demanding a high rate of metabolism. This process that is located in the liver is known as hepatic gluconeogenesis. As we observed the great variation of lactate metabolism between individuals, trainers need to pay detailed attention to creating a fitness program tailored to a player’s lactate metabolism needs.
The other closely related pair of metabolites included glycogen and beta-hydroxybutarate. Both metabolites steadily increased in their rates of production throughout the 90-minute matches. This indicates an increasing reliance on lipolysis from stored energy in fat as play progressed. Lipolysis involves the oxidation of fat, otherwise known as the bonding between oxygen and fat. Therefore, this metabolic process can be referred to as oxidative metabolism. Christmas, Richmond, Cable and Hartmann suggested that endurance training is crucial. Through endurance training, an athlete undergoes fat oxidation, allowing the body to adapt to this metabolic process of the muscles’ glycogen usage in actual competition. In addition, players without intake of food for a longer period of time tended to have higher levels of beta-hydroxybutarate. From this, scientists know that further research in pre-match nutrient consumption is beneficial to a tennis player’s metabolism during play.
NEGATIVE BIOLOGICAL REACTIONS IN TEDIOUS SITUATIONS
As typical individuals who want to reach the full potential in terms of our health, we often monitor our eating habits to ensure that we ingest the recommended daily intake of certain nutrients within our meals. Persistent intake of insufficient amounts of minerals can lead to deterioration of certain parts of our body. For example, an insufficient intake of calcium during childhood increases the likelihood for women to develop osteoporosis as they age. However, intake of excessive amounts of minerals can also lead to the deterioration of certain parts of our body. For example, excessive calcium intake can actually contribute to the development of kidney stones, because excess calcium in the blood stream is likely to be deposited into soft tissues, such as the kidney. Because an athlete’s body undergoes so much strenuous activity during competition, athletes must be even more careful in their nutrient intake. The tennis player replenished of nutrients will undoubtedly have a physical advantage over an opponent who is deprived of nutrients. Furthermore, tennis players must also be prudent in their nutritional intake, as some obtain oral supplements, and thus have the risk of excessive nutritional intake.
Scientists A. Thuminarias, P. Damou, M.F. Chirpaz, J. Etenadossi and A. Favre-Juvin had published a laboratory report in regards to negative biological reactions in a tedious tennis match. The laboratory report was titled “Cramps, heat stroke and abnormal biological responses during a strenuous tennis match”. In their experiment, several women tennis players volunteered to play in a timed competitive match. These matches were played outdoors in scorching temperatures. The women were also limited in their water intake.
As play progressed, several women reported certain negative biological reactions of their bodies to the tedious conditions of the tennis match. As the nutritional profiles of the subjects who exhibited cramping were examined, the scientists noticed that most of these subjects had a noticeable deficiency of a mineral in blood. One subject lacked sufficient magnesium. This subject’s cramps are explainable through the fact that magnesium is required in both anaerobic and aerobic energy generation in prolonged activity. Certain enzymes in the body depend on magnesium to produce adenosine triphosphate (ATP), chemical bonds that store potential energy for the body to convert into useful energy. Taking into consideration the intensity of activity of tennis players, it can be concluded that there needs to be a ready supply of magnesium available to the enzymes at all times. Furthermore, it was confirmed that magnesium deprevation is strongly affiliated with neuromuscular dysfunction, tetani or cramps. (Hughes et al., 1995) When the subject had an insufficient amount of magnesium in her body, her muscles underwent excessive stress as they had to maintain this energy production while simultaneously being contracted and elongated in play. Another subject who exhibited cramping suffered from a difficiency of iron. This subject’s cramping was due to the inefficient rate at which oxygen and carbon dioxide were exchanged in the body. This is because iron is required to form hemoglobin in red blood cells. Hemoglobin is the chemical in red blood cells that transports 97% of the body’s gases. Hemoglobin transports oxygen by temporarily bonding with the oxygen to form a type of iron oxide and then letting go of the oxygen at respiring cells. Without sufficient iron to transport oxygen, this subject’s muscles were overstrained in aerobic energy generation (figure 1).
Figure 1; Muscle Cramping
Muscle cramping can be directly caused by insufficient intake of iron. In the diagram, the purple colour represents insufficient receipt of oxygen of the muscle tissue. Insufficient intake of iron results in a lack of hemoglobin in the red blood cells to transport oxygen. As a result, the muscles are overstrained in aerobic energy generation.
Other than insufficient mineral intake, there was also one subject who experienced cramps due to excessive mineral intake. When examined, the scientists studied that this subject had unusually high levels of glucose. The scientists explained that this subject’s cramping was due to the glucose triggering over-contraction of muscles. This reinforces that although there are certain nutrients that are crucial to a tennis player’s performance, excessive intake of supplements can also be detrimental to the athlete.
EVOLUTION IN TRAITS DOMINANTLY USED WITH GROWTH
As juniors mature, they undergo many physical and psychological changes that influence the traits that they dominantly exhibit when in competition. From observing the league rankings of junior tennis players throughout their career, it is also apparent that the rate of change in predominant traits accelerates with age, as who used to be the “underdog” climbs to the top, or the former undisputed champion can barely keep up with the top ten. These ever-changing traits include:
- Psychological strength- motivation, analytical intelligence
- Physical fitness and build- height, weight, body fat
- Motor abilities- agility, starting speed
Intrigued with the changes exhibited by juniors in development, P. Unierzyski published his laboratory report, “Influence of physical fitness specific to the game of tennis, morphological and psychological factors on performance level in tennis in different age groups”. In his experiment, boys and girls aged 11-14 were examined. Subjects were categorized into either one of the three groups according to their regular level of competition, which included international elite, national elite and other levels of competition. Through this study, Unierzyski projected three conclusions.
- During the younger ages, the chances of winning tournaments are more based upon experience than any other attribute. This was apparent, as amongst the international elite, both boys and girls who were aged 11-12 had started playing tennis at a younger age than 11-12 year olds who belonged to lower levels of competition. Fortunately, for late starters in the game, the determining factor of success by experience decreases with age.
- The capacity of motor abilities takes precedent over playing experience in competition as junior tennis players increase in age. This was apparent, as the subjects aged 11-12 years exhibited little difference in their motor skill capacities. However, by 14 years of age, it was apparent that the international elite players exhibited an immense capacity of starting speed, agility and leg muscular strength, and did not necessarily possess more years of experience, in comparison to 14 years olds in lower levels of competition.
- The state of psychological and physical being increases its influence on a player’s success as age increases, especially with puberty. Girls tend to increasingly rely on their maturing central nervous system, as they have a tendency to prioritize intellectual placement of the ball over striking the ball with power. Taller boys tend to have an advantage over shorter boys, as the taller boys’ height allows them to serve the ball at a greater speed with less effort and be more versatile in running around the court. In both genders, it was apparent that subjects with less body fat usually ranked higher in their league.
REHYDRATION AND SUPPLEMENT INTAKE OF JUNIORS
The appropriate amount of rehydration in any sport is crucial to an athlete, as dehydration may lead to negative biological responses, such as a heat stroke. This is extremely dangerous to juniors, especially, as few extensive studies in regards to rehydration have been specifically targeted at juniors. As well, many people have the misconception that drinks containing electrolytes are necessary for intake during any form of physical activity.
In light of the little information available in regards to rehydration of junior tennis players, K. Kavasis presented his laboratory report, “Fluid replacement needs of young tennis players”. In Kavasis’ experiment, junior volunteers played competitive 90-minute matches with a same aged opponent of similar skill level. Throughout their matches, the junior tennis players ingested water according to their own judgment. Plasma electrolyte concentrations, heart rate and oxygen intake rate and body mass were measured before and after the match. Exercise intensity and stress levels of the junior tennis players were also assessed. After collecting data of the junior tennis players, Kavasis used the following formulas to calculate the water loss of each individual: (Hughes et al., 1995)
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Through calculating the average fluid consumption and average water loss amongst the entire group of subjects, and seeing that the majority of the subjects were able to judge what was a reasonable amount of fluid intake, Kavasis presumed an approximate standard for fluid consumption of junior tennis players. Kavasis projected that as junior tennis players typically reach 55% of their maximum heart rate during a competitive match, as the experiment’s subjects did, they should consume an average of 4.44-6.81mL/kg/min. (The measurement in kg refers to the junior tennis player’s body mass.) In other words, water consumption during competition should be tailored to a junior tennis player’s exercise intensity, body mass and environmental conditions, such as temperature.
In addition to calculating the water loss of subjects, Kavasis also collected data of the concentrations of glucose and electrolyte in subjects’ blood. From initial numbers to resulting data, there appeared to be an increase in glucose and little variations in electrolyte level. It can, then, be concluded that large intake of glucose supplements and sports drinks containing electrolytes are not necessary to the typical junior tennis player.
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