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'On the Web' is an internet-based supplement that provides additional web content to supplement the material in Concepts of Fitness and Wellness. Browse through the whole document to explore web content related to this concept. If you know the specific 'On the Web' number or page number of the web icon in the text you can click on the direct link you are looking for below. Click here to access the other Online Learning Center resources available from the McGraw Hill Website (http://www.mhhe.com/corbin7e). The material available here is for the exclusive use of students and instructors using the Concepts-based textbooks. All rights reserved (McGraw Hill Higher Education). On the Web - Concept 03Web03-01 Guidelines for Safe Exercise Web03-02: Criteria for Selecting Athletic Shoes Web03-03: Clothing for Physical Activity Web03-04: Potential Benefits of a Warm-up Prior to Exercise Web03-05: Heat Regulation during Exercise Web03-06: Fluid Regulation during Exercise Web03-08: Exercise at Altitude Web03-09: Exercise and Pollution Web03-10: Exercise and Delayed Onset Muscle Soreness Web03-11: Common Exercise Injuries and Basic Treatment Web03-12: Automatic External Defibrillators (AED) Web03-13: Supplemental Web Resources Web03-14: Supplemental Readings Web03-01 Guidelines for Safe ExerciseExercise provides many health benefits but participation in exercise does pose some risks. Heart rate and blood pressure both increase during an acute bout of exercise and this can precipitate a heart attack if a person has pre-existing heart conditions or specific risk factors. Click here to read an online article about sudden death during exercise in the journal Physician and Sports Medicine. The Physical Activity Readiness Questionnaire (PAR-Q) provided in the book is a popular tool for assessing the readiness of a person to begin an exercise program. It is not intended as a definitive assessment of safety but as a screening tool to determine if additional medical testing is necessary before exercise would begin. Click here to complete an online PAR-Q evaluation from Health Canada. An interesting activity to fully appreciate the extent to which the PAR-Q is used in the exercise science and fitness field is to conduct a search in a web browser such as google (www.google.com) or yahoo (www.yahoo.com) for the term "Physical Activity Readiness Questionnaire". Note the number of sites that post information on this tool. The American College of Sports Medicine (ACSM) provides recommendations for healthy exercise. Click here to review some basic tips from ACSM for beginning an exercise program. Included at the bottom of the webpage are links to guidelines for healthy aerobic activity, calculating your exercise heart rate range, and information on Healthy People 2010. Web03-02: Criteria for Selecting Athletic ShoesThere are a variety of athletic shoes available for almost every imaginable sport. These specialized shoes provide improved performance and can reduce the risks of injuries during exercise. However, the array of options available to the consumer makes selecting an appropriate shoe a challenging decision. The website of the American Orthopedic Foot and Ankle Society (AOFAS - www.aofas.org) provides consumers with general information about foot care and shoes. A good fit is the most important criteria for any shoe. A variety of factors must be considered to select the type of shoe that is best for your feet. One of the most critical factors is the type of arch you have (ie. high, medium, or low arches). To find out what type you have, wet the bottom of your foot and make a footprint. If the front and back of your footprint is connected by a thin line, you have high-arched feet. If your footprint looks like the bottom of your foot, you have a low arch. A medium arch is in between. Use the general guidelines below to choose the right type of shoe for your particular arch. If you have... high-arched feet--look for a cushioned shoe Click on Dr. Pribut's shoe selection to learn more about how to determine the proper fit for your shoes. To learn more about foot care and shoes browse through the overall AOFAS website. REFERENCES
Web03-03: Clothing for Physical ActivityThere are a variety of other types of athletic clothing that can make you more comfortable in different environments. For example, a variety of wickable fabrics are now available to help draw sweat away from the skin. This keeps you more comfortable in different temperature conditions. In the summer these fabrics can be worn alone and in the winter these fabrics can be used as a base layer to remove sweat from your skin. As the temperature drops, warmer layers can be added to improve your comfort and provide wind blocking capabilities. Other important items for comfort and enjoyment during physical activity include technical socks, watches, and sunglasses. Moisture management socks will help keep your feet dry as well as help prevent blisters. A watch with a chronograph, or timer, will allow you to keep track of your exercise time, and sunglasses will protect your eyes from the sun's harmful rays. The following links will provide information on technical athletic shoes and clothing. Runner's World Shoe Buyers Guide Web03-04: Potential Benefits of a Warm-up Prior to ExerciseMany people skip through their warm-up figuring that they would be better off just jumping right into vigorous exercise. A proper warm-up provides an important transition between rest and exercise and allows the body to perform optimally. A good warm-up can increase muscle/tendon suppleness, stimulate blood flow to the periphery, increase body temperature, and enhance free, coordinated movement. With increased blood flow and temperature, muscles are able to function more efficiently. Specifically, oxygen delivery is enhanced, nerve transmission and metabolism is accelerated, and motor unit recruitment is facilitated. Most people feel better and perform better following a moderate warm-up. There is some controversy, however, on the potential benefits of stretching as a part of a warm-up. In one study (1) , researchers investigated the effects of a pre-exercise stretching on delayed onset muscle soreness (DOMS) that often occurs after strenuous exercise. Hamstring stretches were performed for one leg prior to a series of 10 sets of 10 repetitions of knee flexion. The exercise bout produced severe DOMS but there were no significant differences found between the stretched and non-stretched legs. This study suggests that pre-exercise static stretching was not effective in preventing DOMS.. Another study (2) reviewed the research on stretching and possible risks of injury or pathophysiology of muscle injury. They identified five studies suggesting no difference in injury rates between stretchers and non-stretchers and three studies suggesting that stretching was actually detrimental. They concluded that the research doesn't support a beneficial effect of stretching prior to exercise. A recent study (3) reviewed all relevant research from 1966-2005 and found few studies of high quality on this subject. Of the high quality studies, 3 found that a proper warm-up significantly reduced the risk of injuries. While 2 studies found that a proper warm-up was not effective in reducing injuries. These researchers recommend that more randomized control studies in this field need to still be conducted. Sources:
Read a link on a pre-exercise warm-up from the American Council on Exercise Web03-05: Heat Regulation during ExerciseThe regulation of body temperature is an important physiological process. The body can only function effectively within a narrow range of temperatures and any significant deviation above or below the normal range can lead to serious health problems and even death. For example, excessively high body temperatures can lead to heat injuries ranging from heat cramps, heat exhaustion and heat stroke (in order of severity). Fortunately, the body has a very effective homeostatic mechanism that helps the body maintain temperature. The temperature regulation equation provides a way to remember the various factors that influence core body temperature.  Metabolic heat production (M) refers to heat that is gained through muscular activity. The contraction of muscles builds up internal heat in this way. Radiant heat exchange (R) refers to the transfer of heat from one object to another with no direct contact. Heat is exchanged through a temperature gradient. If outside temperatures exceed body temperature, heat is gained. If outside temperature is less than body temperature, heat is lost. On sunny days, the sun also contributes direct heat to the earth through radiant energy. Convective heat exchange (C) refers to the transfer of heat to either water or air in contact with the body. In this case, air or water molecules are warmed and move away from the heat source and are replaced by cooler molecules. The cooling effect of a fan or the wind are examples of convective heat loss. Convective heat loss from the wind is also the reason for the 'wind-chill' effect in the winter that makes it feel colder with wind. Conductive heat exchange (K) refers to the transfer of heat from a warmer object to a colder object through direct contact. The use of ice or cold towels to cool the body is also an example of conductive heat loss. Evaporative heat exchange (E) refers to heat transferred from the body to water on the surface of the skin. When the water gains sufficient heat, it is converted to a gas and takes heat away from the body. This evaporative cooling takes place even if outside temperature is greater than body temperature. Evaporative heat exchange is the primary mode of heat loss during exercise but this effect is dramatically reduced under humid conditions. Click here to see a chart of heat index and a heat index calculator. Click here to learn more about different heat related illnesses from the National Weather Service. Web03-06: Fluid Regulation during ExerciseMaintaining proper hydration levels is important for body temperature regulation. Fluid replacement is necessary to correct for the loss of body fluids from evaporative heat loss (See Web03-03). Evaporative heat loss occurs under both cold and warm environmental conditions so it is important to replace fluids during and/or following all forms of exercise. Fluid regulation is essential to avoid heat injuries such as heat exhaustion or heat stroke. It is also an important determinant of athletic performance in the heat. The reason for this is that as body fluids are lost, the blood volume decreases and there is less blood available to be pumped around the body. Heart rate increases to help correct for this deficit and causes the heart to work harder for a given level of exercise than when fully hydrated. Research has documented that performance decrements may occur with as little as 1% of body weight loss as fluid. Water is the most obvious fluid to replace the evaporative fluid loss. However, a variety of fluid replacement beverages are also available to consumers. These beverages typically include electrolytes such as sodium and potassium as well as carbohydrates to provide an energy boost during or following exercise. These products have been found to improve endurance performance for exercise lasting over an hour but are not needed for most applications. Initially, there was concern about the use of these products for replacing fluids since there was evidence that the presence of electrolytes and sugar delayed the emptying of fluids from the stomach. Research has demonstrated, however, that the delay in gastric emptying is compensated for by an enhanced absorption of the fluid in the intestines (primarily due to the electrolytes). Therefore, most of these products can provide fluid to the body at the same rate as water. If these products are used, instead of water, it is recommended that the concentration of sugar not exceed 8%. A comparison of some fluid replacement beverages is provided in the table below. Note that drinks like orange juice and soda are higher than this percentage and therefore are not recommended for fluid replacement during exercise.
The Gatorade Sports Science Institute (http://www.gssiweb.com/) has a number of resource documents regarding fluid replacement during exercise. Readers interested in more information are encouraged to look through these materials. The International Body Water Association has an interactive hydration calculator that allows you to determine your fluid needs. HYPONATREMIA References: Web03-07 Exercise in the ColdThe primary environmental concerns during exercise in the cold are from hypothermia or frostbite. Hypothermia refers to a general cooling of the body that occurs when heat is lost more rapidly than when it is produced. Heat loss during exercise is enhanced when the conditions are cold, wet, and windy. There are a number of factors which can further enhance risks for hypothermia including inadequate clothing, exhaustion, anxiety, injury, drugs, poor nutrition, and alcohol consumption.
Frostbite occurs when the body is subjected to subfreezing temperatures for an extended period of time. The body tries to maintain its core body temperature and diverts blood flow from the extremities to the core. Fingers and toes are at the highest risk of frostbite but any exposed area can be harmed. A person can have early signs of frostbite and not even be aware of it since nerve transmission is reduced. If the skin freezes, the cell membranes of the tissue can be permanently disrupted due to ice formation. As the freezing progresses, a sensation of comfortable warmth replaces the initial sensation of cold and burning. This sensation of warmth is a major symptom of a severe frostbite. The skin may also appear white and feel waxy to the touch - numbness may also occur. If frostbite occurs, do not thaw the area if there is a chance the area may become frostbit again. The best treatment is to rewarm the area gradually in water that is 102¬?F-104¬?F for 30-40 minutes (rewarming may be very painful). Dry the area and seek immediate medical attention for follow-up care. Click here to see the Wind Chill Chart prepared by the National Weather Service. Web03-08: Exercise at AltitudeMany people have experienced the out of breath sensation that occurs when climbing or skiing at a high altitude. The reason for this is that the high altitude makes it harder to obtain the necessary amounts of oxygen for the aerobic metabolism. As one moves to higher altitudes, the atmospheric pressure decreases meaning that the air becomes less dense or has fewer molecules of gases unit volume than at lower elevations. Since the percentage of oxygen is a constant at all altitudes, there is a reduction in the partial pressure of oxygen at altitude. This has a direct effect on the saturation of hemoglobin (the oxygen carrying component) in the blood. Because there is less oxygen available, the effect of altitude poses an additional challenge to the body. The body compensates by increasing respiration and heart rate to try to make up for this deficit. Thus, at any given level of exercise, the body has to work harder to provide the oxygen needed for exercise. With continued exposure to altitude, the body acclimatizes to the altitude and develops adaptations that allow the body to perform more effectively under these conditions. These adaptations occur with normal resting exposure but additional adaptations occur for people that exercise under these conditions. Individuals who quickly move from lower elevations to higher elevations (for a skiing vacation, for example), have to be particularly careful to avoid altitude sickness. This condition typically affects individuals at altitudes of 8000 feet as the body tries to quickly adjust to the different environmental conditions. The mechanisms of altitude sickness are not totally understood but the effect usually begins 4-6 hours after arrival at altitude. Signs and symptoms include headache, lack of energy, nausea, dizziness, weakness, insomnia, More severe symptoms may include extreme headache, irritability, nausea, vomiting, shortness of breath with exercise, marked fatigue, irregular or periodic breathing, apnea. The key to avoiding acute mountain sickness is to drink plenty of fluids, eat light, allow a gradual exposure to altitude and limit exercise for the first few hours or days at altitude. Descent to a lower altitude is rarely needed for mountain sickness but medical attention should be sought if symptoms persist. Click here to read guidelines for proper acclimatization to altitude. Web03-09: Exercise and PollutionMany people are rightfully concerned about the potential hazards of air pollution, particularly the increased exposure to air that occurs during exercise. Air pollution includes a variety of gases that are most directly related to the high degree of combustion of fossil fuels in our society. The "smog" that accumulates, particularly in large cities reflects a high concentration of these pollutants. These gases have a negative effect on health and can influence performance during exercise. The most common pollutants are ozone, sulfer dioxide and carbon monoxide. Because of the established links between pollution and asthma, the American Lung Association www.lungusa.org is also actively involved in air quality issue. They report that the number of asthma related deaths, like asthma cases, have been rising both in numbers and rate. The number of deaths attributed to asthma increased by 117% between 1979 and 1995. Click here for more information on asthma from the ALA. To promote awareness of this issue in the public, they recently released a document called State of the Air that summarizes the air quality in specific cities and counties in the United States. They also rate the best and worst metropolitan areas in terms of ozone and pollution control. Follow the guidelines below to minimize your exposure to air pollution: Watch The Calendar:Ozone smog tends to be worst during May-to-September. Watch the Clock:The highest levels of ozone typically occur during the afternoon. Since carbon monoxide is produced primarily by motor vehicles, the highest carbon monoxide levels usually occur during rush hour or during other traffic congestion situations. Watch the News:Pollution levels are often given with weather reports and printed in newspapers. The reports use an air pollution index to rank the air quality on a scale from 0 (pristine air) all the way up to 500 (immediate danger). Pollution control officials often can predict when pollution levels will be high. Click here to access the EPA's Air Now site to get updated information on current ozone levels in your area. Web03-10: Exercise and Delayed Onset Muscle SorenessA common experience for many exercisers is a certain degree of muscle soreness following a bout of exercise. This is usually called Delayed Onset Muscle Soreness (DOMS). A variety of possible mechanisms have been proposed to account for this but the leading explanation is that DOMS is due to microscopic tissue damage that results from the excessive mechanical forces occurring during exercise. Soreness is not a normal part of the bodies' response to exercise but occurs if an individual violates the principle of progression and does more exercise than the body is prepared for. The image below shows a microscopic image of skeletal muscle damage. To help understand the nature of the damage it is important to understand the basic function of the muscular system. On a microscopic level, a muscle fiber is divided into functional units known as sarcomeres. The sarcomere can be identified on the image as the distance between the two dark bands which are called "Z - lines". Under normal conditions the Z-lines from adjacent muscle fibers are aligned to allow for effective and coordinated muscle contractions. The image below shows that the Z-lines are not well aligned (this is called "Z - line disruption"). This disruption hampers the function of the muscle and causes the tight and constrained feelings in the muscles. The actual soreness is caused by an inflammatory response elicited to help the body repair the damage.  While the body eventually repairs this microscopic damage it is better to avoid the soreness and restriction by adding new exercises slowly or by progressing the intensity, volume or duration of activity in a reasonable and progressive manner. A recent review study indicates that massage can facilitate recovery from DOMS (1) but a different study indicated that passive stretching may not be effective (2). Sources: Web03-11: Common Exercise Injuries and Basic TreatmentParticipation in physical activity increases the risk for various types of musculoskeletal injuries. One of the most common exercise injuries is a sprained ligament. Ligaments are a type of connective tissue that connects bones together. When a joint is exposed to an extreme range of motion due to a slip or strong force, the ligament can be stretched or torn. Sprains are typically graded on a 3-point scale by severity or degree (3 being the most severe). Another common exercise-related injury is a muscle strain. While sprains are more likely the result of an acute trauma or fall, muscle strains are most commonly associated with overuse. Like ankle sprains, these are graded on a 1,2, or 3 scale with a 3 being the most severe injury. A common site for a muscle strain is the hamstring since the quadriceps are usually stronger and can overpower the hamstring during sprinting or high-intensity activities. Basic treatment for ankle sprains should follow the RICE principle (REST, ICE, COMPRESSION and ELEVATION). Maintenance of range of motion (with stretching exercises) and ankle support are also recommended for the management of ankle sprains. Early motion and mobility are recommended following a sprain but full ligamentous strength does not return until months after an ankle sprain so caution is recommended. Many people recommend the use of anti-inflammatory agents to reduce the swelling. Understanding proper guidelines for use of these agents is difficult and should be based on direct advise from physicians. To become more educated about them click on the information link for anti-inflammatory agents from the MedHelp website. Other common exercise related injuries include shin splints, side stitch or cramps, and tendonitis. Shin splints is a generic name for any pain that is found on the front or inside of the lower leg. It is generally caused through overuse. A side stitch is a sharp pain that can be felt just below the rib cage especially during endurance activities. It is generally believed to be caused by a lack of oxygen in the blood flow to that region of the body. Tendonitis is a condition that can also be caused by overuse where a tendon becomes inflamed. Depending on the tendon that is affected, a decrease in activity or cross training may be recommended.
Web03-12: Automatic External Defibrillators (AED)The recent evidence concerning the effectiveness of public access defibrillation (PAD) using automated external defibrillators (AED) has created new needs in the field. The American Heart Association has developed a course called Heartsaver that covers CPR and techniques for using an AED (see www.americanheart.org). The American Red Cross also has several training courses that include AED training (see www.redcross.org). Home defibrillators are also becoming more common (see www.heartstarthome.com). AEDs are portable devices that are used to restore a heart's normal rhythm. Pads are applied to the patient's chest and directions from the machine should be followed. The AED will monitor the patient's heart rhythm and inform the rescuer if a shock is needed. See the links below for more information on AEDs.  Web03-13: Supplemental Web ResourcesACSMS's Fit Society Page - http://www.acsm.org/health+fitness/fit_society.htm Web03-14: Supplemental ReadingsReferences new to 7e/14eAlmond, C. S. D. et al. 2005. Hyponatremia among runners in the Boston Marathon. New England Journal of Medicine. 352(15): 1550-1556. Asplund, C. A. and D. L. Brown. 2005. The Running Shoe Prescription: Fit for Performance. The Physician and Sportsmedicine. 33(1):17-24. Montain, S. J. et al. 2006 Exercise associated hyponatraemia: quantitative analysis to understand the aetiology. British Journal of Sports Medicine. 40: 98-105. Noakes, T. D. 2006. Sports drinks: Prevention of "voluntary dehydration" and development of exercise-associated hyponatremia. Medicine & Science in Sports & Exercise. 38(1):193 Noakes, T. D. 2005. Mind over matter deducing heatstroke pathology. The Physician and Sportsmedicine. 33(10):39-58 Shrier, I. 2005. An intervention program to reduce hamstring injuries. Physician & Sportsmedicine. 33(12):8-8. Rererences from Past Editions
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