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Select one of the following sports: soccer, basketball, volleyball, distance running (5000 meters), or track (200-meter dash). Indicate athlete gender and approximate age.
Outline the general principles for designing an appropriate training program for the athlete in your selected sport. List and discuss the objectives of this athlete’s off-season conditioning, preseason conditioning, and in-season conditioning. What are some of the more common errors made in training this type of athlete for this sport? What are some additional professional recommendations or considerations you may have for this athlete given the sport, gender, and age?
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Exercise Physiology – Ch. 19-22 https://online.vitalsource.com
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08 Lecture Notes
This week, we will look at the physiology of performance-specifically the factors that affect performance, how to assess performance in a laboratory setting, and methods of training for improved performance-including the most appropriate methods for women, children, and other special populations.
Performance goals require much more time, effort, and risk of injury than other fitness goals. Diet, central nervous system functioning, the environment, energy production, and an individual’s strength and skill all affect performance.
Have you ever noticed how fatigue impacts your performance-in all areas of life? When we are tired, our motivation and reflexes decrease, and whatever we are trying to accomplish suffers.
In exercise performance, our fatigue is the inability to maintain a power output or force during repeated muscle contractions. There are several possible sites where the fatigue could originate, and include the brain, spinal cord, or the muscles themselves.
Researchers have different opinions about what causes fatigue, based in part on the differences in how they study it. Depending on the nature of the exercise, the individual’s overall fitness, and the method used to study fatigue, different results can be discovered. There are advantages and disadvantages to each of the research methods, and their limitations should be kept in mind.
Two terms important to the study of fatigue are central fatigue and peripheral fatigue.
Central fatigue-the type that originates in the central nervous system-is caused by a reduction in the number of functioning motor units involved in the performance activity or a reduction in motor unit firing frequency. Over the last several years, research studies have found contradicting evidence of central fatigue, however there is consensus that the central nervous system is intimately involved in exercise. How the brain begins exercise with a motivation to perform, and ends exercise by reducing power output to halt performance and protect the human body, perpetuates continued research on central fatigue.
Peripheral fatigue is where most of the evidence points, and suggests that neural, mechanical, or energetic events hamper tension development in muscles during performance resulting in fatigue. Examples of peripheral fatigue resulting from a neural factor include a repeated stimulation of the sarcolemma resulting in a reduction in the size and frequency of action potentials, and an action potential block in the t-tubule resulting in a reduction in the calcium release from the sarcoplasmic reticulum.
One mechanical factor that may be related to fatigue is cross-bridge cycling. This phenomenon results typically in heavy exercise due to either a reduction in the force per cross-bridge, a reduction in the force generated at a given calcium concentration, or an inhibition in the calcium release. This type of fatigue manifests in a longer relaxation time in isometric contractions.
The energetics of muscle contractions are related to a simple imbalance between the ATP requirements of a muscle and its ATP-generating capacity. When the rate at which the muscles use ATP and the rate at which ATP can be supplied do not match, muscles may be fatigued. Slide 3
As exercise intensity increases, the ATP supply needed for tension development becomes increasingly dependent on anaerobic metabolism. Ultra-short performances, such as the high jump and 50-meter sprints, require tremendous amounts of energy to be produced in a short period of time and utilize type II muscle fibers for energy production. Maximal performance for these events is limited by the fiber type distribution and the number of muscle fibers recruited. Motivation, arousal, skill, and technique also impact performance in these events.
Short-term performances lasting up to 60 seconds are still predominately anaerobic, however when a maximal performance extends to 180 seconds, about 60% of the energy comes from a slower aerobic, ATP-generating process. As a result of this switch, maximal running speed decreases with the increase of performance duration.
Moderate-length, intermediate-length, and long-term performances are all considered aerobic performances, and factors influencing performance include increasing demands placed on the aerobic sources of energy, environmental factors such as heat and humidity, and dietary factors such as hydration.
One of the ethical concerns in exercise physiology is how we assess the athlete’s performance. When elite athletes are treated like racing cars in which scientists and coaches try and spot weaknesses in order to recommend solutions, just like engineers and mechanics do with automobiles, does the athlete’s personhood become exploited?
There are several different opinions on this issue, which is why universities, hospitals, and research centers have Institutional Review Boards that oversee all research on human subjects to ensure that the rights of those subjects are protected. Additionally, research journals require that authors submitting articles to their journal follow all research guidelines if they want their article published.
Physical performance is measured in two different ways-field tests that require basic performance demands and laboratory assessments of the body’s capability, such as VO2 max, anaerobic power, and exercise economy. While testing basic performance is important, detailed physiological information that is provided through lab testing provides a better profile for assessing performance related to specific athletic events.
Generally speaking, physical performance is determined by the individual’s capacity for maximal energy output, muscle strength, coordination of movement, psychological factors such as motivation, and the environment. Lab testing understands that each of these factors is essential optimal performance in a particular athletic event and can assess performance accordingly.
The athlete benefits from lab testing in at least three major ways:
1) The athlete’s strengths and weaknesses are identified, which can aid in the development of training programs.
2) Feedback can be given about the effectiveness of a particular training program.
3) Lab testing can increase an athlete’s understanding of exercise physiology, which may help the athlete to make better personal decisions regarding exercise training and diet and other lifestyle choices.
To optimize efficiency of laboratory assessments, physiological testing should meet several criteria.
First, testing should be relevant to the sport. Assessing handgrip is not important for a sprinter because it is irrelevant to the sport.
Secondly, the test itself should be valid and reliable, which means that it should measure what it is supposed to measure and be reproducible across time.
Third, tests should be sport specific, and assess an athlete in similar or identical skills to what a sporting event requires. Runners should be tested while running, cyclists should be tested while cycling, and so on.
Fourth, tests should be repeated at regular intervals so that feedback can increase training effectiveness.
Fifth, testing should be standardized so that a test’s reliability is unquestionable. Factors that should be controlled to assure standardization include properly calibrating the instruments involved in testing, controlling for environmental conditions such as heat and humidity, assuring consistency in prior exercise and the athlete’s diet, and checking for hydration and injury.
The last criterion for assuring that physiological testing is efficient is assuring that test results are clearly interpreted and well communicated to the athlete and coach.
Common lab tests to predict endurance performance include measuring lactate threshold, critical power, and peak running velocity.
The lacate threshold can be determined using a treadmill, cycle ergometer, or any other appropriate exercise modality and represents an exercise intensity in which blood lactate levels begin to systematically increase. Critical power is defined as the power output at which the running speed/time reaches a plateau, while peak running velocity is determined on a treadmill or track and defined as the highest speed that can be maintained for more than five seconds. Slide 8
Muscular strength testing assesses the maximum force that can be generated by a muscle or muscle group. Evaluating muscular strength is especially useful in assessing training programs for athletes involved in power sports or events, such as American football players and weight lifters. Muscular strength can be evaluated using isometric or free-weight testing, isokinetic techniques, or variable-resistance devices such as specialized weight machines that vary resistance with normal range of movement.
Now, let’s shift our focus to performance training. We begin by reviewing some fundamental training principles.
The overall goal of a sport conditioning program is to improve performance. Depending on the sport, or competitive events, improving an athlete’s performance can be achieved by increasing the muscle’s ability to generate force and power, improving muscular efficiency, and/or increasing muscular endurance. A well-designed conditioning program will allocate the appropriate amount of aerobic and anaerobic conditioning time to match the energy demands of the sport. For example, the energy needed by1500-meter runners is 40% of its ATP from anaerobic pathways and 60% from aerobic pathways. This means that an appropriate training program should be divided into 40% of anaerobic training and 60% aerobic training.
Important considerations for performance training are overload, which can lead to overtraining or overreaching; specificity, and reversibility. Overtraining is defined as an accumulation of training stress that impairs an athlete’s ability to perform training sessions and results in long-term decrements of performance. Examples of overtraining include chronic fatigue and mood disturbance. Recovery can restore performance but may require up to months of reduced exercise training.
Overreaching is defined as excessive training that leads to a short-term reduction in performance. With adequate rest in between training sessions, overreaching can actually improve performance over time.
Specificity relates to both the muscles and the energy systems involved in performance. Training programs should be designed to use the specific muscle groups involved in competition and the energy systems that supple the ATP required to complete muscle movement during competitive conditions.
Finally, reversibility refers to what happens when the athlete stops training. Studies have shown that within two weeks of halting training, significant reductions VO2 max can occur. Reversibility should be taken into consideration during off-season and other similar circumstances in an athlete’s career.
Every training session should include a warm-up period, workout session, and a cool-down period, as we learned about in week 7. Warming up increases cardiac output and blood flow to the skeletal muscles to be used during training and increases muscle temperature, elevating enzyme activity. Warm-ups typically last 10 to 20 minutes and may reduce the risk of injury while improving performance potential.
Following a workout session, low-intensity cool-down exercises will help return the pooled blood from the exercised muscles back to the body’s central circulation. This also lasts between 10 and 20 minutes depending on environmental conditions and the nature of the training session.
Slide 11 Training to improve maximal aerobic power has historically used three methods: interval training, long, slow-distance exercise, and high-intensity, continuous exercise. Recent research suggests that intensity, rather than duration, is the most important factor for improving VO2 max.
Most training injuries are the result of overtraining and can result from either short-term, high-intensity exercise or prolonged, low-intensity exercise. One way to increase the training load without increasing the risk of injury is to remember that training intensity or duration should not be increase more than ten percent from one week to the next. Incremental increases are best.
Training to improve anaerobic power involves a special type of interval training that utilizes short duration, high-intensity exercise. This type of training is physically and psychologically demanding and requires a high commitment from the athlete. Because of these demands, athletes are often advised to alternate hard-interval training days and light training sessions to avoid injury and burnout.
Improving muscle strength can be achieved by progressively increasing demands using either isometric, isotonic, or isokinetic exercise. Because isometric strength gains only occur at the specific joint angles that are held during isometric training, both isotonic and isokinetic training are preferable for developing strength in athletes.
While one agreed upon formula for strength training does not exist, there does exist a general guideline for strength-training. The most common recommendation for intensity training is 8-12 maximal repetitions practiced in multiple sets. Rest days between workouts seem to increase optimal strength improvement. Training schedules of two to four days per week is typically recommended for novice or immediate individuals, while those engaged in advanced weight training benefit from four to six days per week when using split routines.
Training to improve flexibility has been historically believed to reduce the risk of exercise-induced injury. However, limited evidence actually exists to support this argument. Nevertheless, stretching is recommended to improve the body’s overall flexibility and optimize the efficiency of muscular movement. Improving flexibility can be achieved through static stretching-which is continuously holding a stretch position-or dynamic stretching-which is the ballistic stretching when movements are not controlled, with static stretching being the preference because the reduced chance of injury.
The last portion of this week’s lecture looks at training specifics for women, children, special populations, and the masters athlete. While the general physiological principles of exercise training to improve performance apply to anyone, when planning competitive training programs for special populations, there are several specific issues that require additional consideration.
Female athletes may experience menstrual disorders, such as amenorrhea or dysmenorrhea due to over training, psychological stress, and low energy availability. These conditions may necessitate a physician consultation and training should be modified accordingly.
Eating disorders affect over 10 million women in the United States, and female athletes are especially susceptible to anorexia nervosa and bulimia.
Anorexia nervosa is an eating disorder in which the individual eventually enters a state of starvation and emaciation. While the causes are unknown, it is likely linked to an unfounded fear of fatness associated with pressures to be an ideal weight, shape, or look. A person with anorexia may show signs with rapid and extreme weight loss; excessive exercise; preoccupation with food, calories, and weight; and cessation of menstruation.
Bulimia is characterized by binge eating and purging and may result in damage of the teeth and esophagus due to the excessive vomiting of stomach acids. Most people with bulimia look normal and are within their ideal weight, however they may exhibit other warning signs such as bathroom visits after meals, strict dieting followed by eating binge, excessive concern about weight, and an increasing criticism of one’s body. The sports with the highest incidents of earing disorders are distance running, swimming, diving, figure skating, gymnastics, body building, and ballet. Trainers and coaches should be able to recognize warning signals and be prepared to assist any athlete with finding professional help.
One important physiological distinction between male and female athletes is the increased risk in women for knee injuries. Evidence suggests that differences in leg muscle strength and/or jumping and landing strategies may contribute to women’s increased risk. Trainers and coaches should be aware of the existing programs aimed at reducing ACL injury in women and help female athletes adjust their performance training accordingly.
Endurance training is neither detrimental to the growth and development of cardiovascular system in children, nor has a negative impact on bone and cartilage health. Under proper supervision, resistance training can be performed safely in young athletes, and may even increase both bone density and muscular strength in prepubertal children.
Masters athletes are individuals over the age of 50 and who compete in athletic events. They often train on a daily basis and strive to maintain athletic performance that was achieved at earlier ages. While a decline in athletic performance is both normal and inevitable, many of these athletes possess unique physiological characteristics that demonstrate exceptionally successful aging.
Because of the age-related decline in muscle mass and muscular strength begins around 50-years-of-age, regular bouts of resistance exercise training can assist in maintaining muscle mass and muscular strength throughout the entire lifespan. The progressive decline in endurance performance is largely due to a decrease in VO2 max. While endurance exercise training cannot completely halt the decline in cardiac output, it can protect against some of the age-related decreases.
This concludes our week 8 lesson. Next week, we will finish the course with a review of nutrition and body composition for performance training, how the environment affects exercise, and the use of performance enhancing substances.