Sports can be a great way to get in shape or stay that way. Having a specific goal can be a great motivator. Physically, you need strength and endurance. Your training will vary with your sport. You would not train the same way for pole vaulting as for swimming. You might, however, cross train. Cross training simply means that you include a variety of fitness activities in your program. Research shows that cross training builds stronger bones.

Remember to listen to your body. If you frequently feel exhausted or you are in pain, you may be overdoing it. Injuries can be the result. And be sure that you use your body and your equipment safely. What you eat and drink is also important. Water is the most important nutrient for active people. Drink it before, during and after workouts.

Physical activity is any body movement that works your muscles and requires more energy than resting. Walking, running, dancing, swimming, yoga, and gardening are a few examples of physical activity.

Aerobic means "oxygen-producing." Aerobic exercise, sometimes called endurance training, improves oxygen consumption by your body and strengthens your cardiovascular system and endurance. Activities like walking, running, swimming, and biking, in which you remain in motion and your heart rate increases for an extended period of time, are considered aerobic. When your heart is beating more rapidly, more blood is circulated around your body and more oxygen is provided to your tissues and cells.

Your heart is a muscle like any other in your body, and with regular exercise it will become stronger and slightly larger. (This is different from an enlarged, or hypertrophied, heart, in which the heart muscle thickens and actually becomes weaker.) A stronger heart can pump more blood with each beat, so that it takes fewer beats to circulate your blood. Your heart rate drops, and your heart is able to rest more between beats. But if you don't get enough exercise, your heart is weaker, has less muscle tone, and has to work harder to pump the blood. This raises your blood pressure and stresses your whole cardiovascular system.

As you progressively condition your heart with aerobic exercise, not only does your heart become stronger, but your entire body responds. New capillaries grow in your muscles and in the heart muscle itself. In fact, endurance-trained athletes have 40% more capillaries per muscle than untrained people. Your muscle cells themselves change in ways that allow them to extract greater amounts of oxygen and nutrients from the bloodstream and use them to produce energy. Your blood pressure lowers, and your body produces more red blood cells to transport oxygen.

Exercise strengthens bones ligaments and tendons by encouraging the laying down of connective tissue. Your joints become stronger and less prone to injury. Your bones will also lose less calcium as you age, helping to prevent osteoporosis.

Moderate Intensity vs. Short Bursts

It's long been thought that aerobic exercise works best when performed at moderate intensity over a long period of time. But new evidence shows that short, intense bursts of exercise may work just as well for cardiovascular health. In one study, doing about 50 minutes of moderate-intensity cycling 5 days a week provided the same benefits to the arteries as doing short, intense cycling sprints (resting between sprints) for a total of about 20 minutes, just 3 days a week. Consider this type of exercise if time is an issue for you, but consult your doctor first, as intense exercise may increase the risk of injury.

Basal Metabolic Rate

Basal metabolic rate is the measure of the energy necessary for maintaining basic functions, such as breathing, heart rate, and digestion.

NIH MedlinePlus

Metabolic Rate

The metabolic rate is the amount of energy consumed minus the amount of energy expended by the body. The basal metabolic rate (BMR) describes the amount of daily energy expended by humans at rest, in a neutrally temperate environment, while in the postabsorptive state. It measures how much energy the body needs for normal, basic, daily activity. About 70 percent of all daily energy expenditure comes from the basic functions of the organs in the body. Another 20 percent comes from physical activity, and the remaining 10 percent is necessary for body thermoregulation or temperature control. This rate will be higher if a person is more active or has more lean body mass. As you age, the BMR generally decreases as the percentage of less lean muscle mass decreases.

How do you know if you’re considered overweight or obese? Recent guidelines call for classifying obesity by measuring body mass index (BMI). A BMI between 18.5 and 24.9 is normal; a BMI between 25.0 and 29.9 is overweight; a BMI between 30.0 and 39.9 is obese; and a BMI of over 40 is morbidly (severely) obese.

How to Measure Your BMI

Calculating BMI is done using your weight and height. Measure your weight in pounds or kilograms using a basic-model or bioimpedance scale. You’ll need to measure your height in inches or meters using a tape measure or yardstick. Once you have these numbers, use one of the following equations:

IMAGE: BMI formula using pounds (lbs) and inches (in)

IMAGE: BMI formula using kilograms (kg) and meters (m)

If you’re a little rusty with a calculator, you can use the following chart instead. Or, once you have your accurate height and weight, you can use one of the many online BMI calculators to compute your body mass index for you.

Pros of BMI

• BMI is an inexpensive and easy way to calculate body mass
• It has standardized cutoff points for overweight and obesity
• BMI correlates fairly well with body fat percentage as measured by the most accurate methods

Cons of BMI

• BMI does not take into account differing age, gender, or body composition. For example, a bodybuilder with dense bones and a muscular build may be labeled as overweight according to BMI classifications, when he clearly is not. On the other side of the equation, elderly people with low bone density and low muscle mass may weigh less than others of the same height, even if they carry too much body fat. They may therefore have misleadingly low BMIs.

Your physical activity session should end by gradually slowing down. You can also cool down by changing to a less vigorous activity, such as moving from jogging to walking. This process allows your body to relax gradually. A cool down can last 5 minutes or more.

Energy Balance

The balance between calories you get from eating and drinking and those you use up through physical activity and body processes like breathing, digesting food, and, in children, growing.
National Institute of Diabetes and Digestive and Kidney Diseases

The body tightly regulates the body temperature through a process called thermoregulation , in which the body can maintain its temperature within certain boundaries, even when the surrounding temperature is very different. The core temperature of the body remains steady at around 36.5–37.5 °C (or 97.7–99.5 °F). In the process of ATP production by cells throughout the body, approximately 60 percent of the energy produced is in the form of heat used to maintain body temperature. Thermoregulation is an example of negative feedback.

The hypothalamus in the brain is the master switch that works as a thermostat to regulate the body’s core temperature (image). If the temperature is too high, the hypothalamus can initiate several processes to lower it. These include increasing the circulation of the blood to the surface of the body to allow for the dissipation of heat through the skin and initiation of sweating to allow evaporation of water on the skin to cool its surface. Conversely, if the temperature falls below the set core temperature, the hypothalamus can initiate shivering to generate heat. The body uses more energy and generates more heat. In addition, thyroid hormone will stimulate more energy use and heat production by cells throughout the body. An environment is said to be thermoneutral when the body does not expend or release energy to maintain its core temperature. For a naked human, this is an ambient air temperature of around 84 °F. If the temperature is higher, for example, when wearing clothes, the body compensates with cooling mechanisms. The body loses heat through the mechanisms of heat exchange.

Overview

Some of the energy from the food that is ingested is used to maintain the core temperature of the body. Most of the energy derived from the food is released as heat. The core temperature is kept around 36.5–37.5 °C (97.7–99.5 °F). This is tightly regulated by the hypothalamus in the brain, which senses changes in the core temperature and operates like a thermostat to increase sweating or shivering, or inducing other mechanisms to return the temperature to its normal range. The body can also gain or lose heat through mechanisms of heat exchange. Conduction transfers heat from one object to another through physical contact. Convection transfers heat to air or water. Radiation transfers heat via infrared radiation. Evaporation transfers heat as water changes state from a liquid to a gas.

Energy Consumed

Energy is another word for calories. What you eat and drink is "energy in." What you burn through physical activity is "energy out."

National Heart, Lung, and Blood Institute

Scientists use the term bioenergetics to discuss the concept of energy flow (image 1) through living systems, such as cells. Cellular processes such as building and breaking down complex molecules occur through stepwise chemical reactions. Some of these chemical reactions are spontaneous and release energy; whereas, others require energy to proceed. Just as living things must continually consume food to replenish what they have used, cells must continually obtain more energy to replenish that which the many energy-requiring chemical reactions that constantly take place use. All of the chemical reactions that transpire inside cells, including those that use and release energy, are the cell’s metabolism.

Carbohydrate Metabolism

Sugar (a simple carbohydrate) metabolism (chemical reactions) is a classic example of the many cellular processes that use and produce energy. Living things consume sugar as a major energy source, because sugar molecules have considerable energy stored within their bonds. The following equation describes the breakdown of glucose, a simple sugar:

C6H12O6+6O2→6CO2+6H2O+energyC6H12O6+6O2→6CO2+6H2O+energy

Consumed carbohydrates have their origins in photosynthesizing organisms like plants (image). During photosynthesis, plants use the energy of sunlight to convert carbon dioxide gas (CO₂) into sugar molecules, like glucose (C₆H₁₂O₆). Because this process involves synthesizing a larger, energy-storing molecule, it requires an energy input to proceed. The following equation (notice that it is the reverse of the previous equation) describes the synthesis of glucose:

6CO2+6H2O+energy→C6H12O6+6O26CO2+6H2O+energy→C6H12O6+6O2

During photosynthesis chemical reactions, energy is in the form of a very high-energy molecule scientists call ATP, or adenosine triphosphate. This is the primary energy currency of all cells. Just as the dollar is the currency we use to buy goods, cells use ATP molecules as energy currency to perform immediate work. The sugar (glucose) is stored as starch or glycogen. Energy-storing polymers like these break down into glucose to supply ATP molecules.

Solar energy is required to synthesize a glucose molecule during the photosynthesis reactions. In photosynthesis, light energy from the sun initially transforms into chemical energy that temporally stores itself in the energy carrier molecules ATP and NADPH (nicotinamide adenine dinucleotide phosphate). Photosynthesis later uses the stored energy in ATP and NADPH to build one glucose molecule from six molecules of CO₂. This process is analogous to eating breakfast in the morning to acquire energy for your body that you can use later in the day. Under ideal conditions, energy from 18 molecules of ATP is required to synthesize one glucose molecule during photosynthesis reactions. Glucose molecules can also combine with and convert into other sugar types. When an organism consumes sugars, glucose molecules eventually make their way into each organism's living cell. Inside the cell, each sugar molecule breaks down through a complex series of chemical reactions. The goal of these reactions is to harvest the energy stored inside the sugar molecules. The harvested energy makes high-energy ATP molecules, which perform work, powering many chemical reactions in the cell. The amount of energy needed to make one glucose molecule from six carbon dioxide molecules is 18 ATP molecules and 12 NADPH molecules (each one of which is energetically equivalent to three ATP molecules), or a total of 54 molecule equivalents required for synthesizing one glucose molecule. This process is a fundamental and efficient way for cells to generate the molecular energy that they require.

Metabolic Pathways

The processes of making and breaking down sugar molecules illustrate two types of metabolic pathways. A metabolic pathway is a series of interconnected biochemical reactions that convert a substrate molecule or molecules, step-by-step, through a series of metabolic intermediates, eventually yielding a final product or products. In the case of sugar metabolism, the first metabolic pathway synthesized sugar from smaller molecules, and the other pathway broke sugar down into smaller molecules. Scientists call these two opposite processes—the first requiring energy and the second producing energy—anabolic (building) and catabolic (breaking down) pathways, respectively. Consequently, building (anabolism) and degradation (catabolism) comprise metabolism.

Anabolic and Catabolic Pathways

Anabolic pathways require an input of energy to synthesize complex molecules from simpler ones. Synthesizing sugar from CO₂ is one example. Other examples are synthesizing large proteins from amino acid building blocks, and synthesizing new DNA strands from nucleic acid building blocks. These biosynthetic processes are critical to the cell's life, take place constantly, and demand energy that ATP and other high-energy molecules like NADH (nicotinamide adenine dinucleotide) and NADPH provide (image 3).

ATP is an important molecule for cells to have in sufficient supply at all times. The breakdown of sugars illustrates how a single glucose molecule can store enough energy to make a great deal of ATP, 36 to 38 molecules. This is a catabolic pathway. Catabolic pathways involve degrading (or breaking down) complex molecules into simpler ones. Molecular energy stored in complex molecule bonds release in catabolic pathways and harvest in such a way that it can produce ATP. Other energy-storing molecules, such as fats, also break down through similar catabolic reactions to release energy and make ATP (image 3).

It is important to know that metabolic pathway chemical reactions do not take place spontaneously. A protein called an enzyme facilitates or catalyzes each reaction step. Enzymes are important for catalyzing all types of biological reactions—those that require energy as well as those that release energy.

Flexibility training is exercise that stretches and lengthens your muscles. It can help improve your joint flexibility and keep your muscles limber. This can help prevent injuries. Some examples are yoga, tai chi, and pilates.

Why Is Flexibility Important?

The role of flexibility in physical fitness has been debated since the 1950’s, and studies have shown inconsistent results when measuring flexibility outcomes with physical activities. That being said, few clinicians would argue against the benefits of maintaining range of motion to effectively perform activities of daily living. Moreover, some studies show reasonable benefit from stretching in the setting of age-related loss of functionality and management of chronic illnesses.

While more research is still needed regarding the specific role of flexibility in overall physical fitness and health, most experts agree that structured flexibility exercises improve patients’ general health. Preliminary studies have suggested that flexibility may reduce arterial stiffening, which could theoretically reduce cardiovascular disease rates. Stretching can also improve heart rate variability, reduce resting heart rate in patients, and decrease blood pressure. Finally, flexibility exercises have consistently demonstrated benefits in short-term and long-term balance performance.

Current research suggests that warm-up stretching does not immediately reduce the risk of athletic injuries. However, with regular stretching over weeks, there appears to be a long-term benefit in improving muscle power and force, which can positively impact athletic performance. Some studies have also shown a correlation with less work-related injuries when chronically stretching in the workplace. Additionally, certain medical conditions such as osteoarthritis[8] and adhesive capsulitis[9] often warrant special attention to chronic flexibility training to preserve or regain function and reduce discomfort.

Despite inconsistencies in current research on flexibility training, being able to move the body in a wider range of positions and movements gives us more options for accomplishing work, enjoying play, and expressing ourselves. When flexibility increases, our range of possibility increases.

What Factors Affect Flexibility?

There are a variety of factors that contribute to a given persons tendency to be more flexible or stiff. Females tend to be more flexible than males, and flexibility generally declines with age.  Numerous genetic conditions such as Marfans syndrome and other connective tissue disorders affect flexibility. Joint hypermobility and joint hypermobility syndrome are two overlapping and somewhat poorly understood conditions associated with pronounced flexibility. These conditions exist on a continuum of severity, affect up to 30% of the population, and exhibit a strongly heritable risk pattern.

High degrees of flexibility achieved at a young age may be subsequently maintained into adulthood. For example, athletes and artists who exhibit high degrees of flexibility, such as gymnasts and contortionists, typically require initiation of flexibility training at a young age. Long-term conditioning through training and habit undoubtedly contributes to long-term flexibility differences.

How Can Flexibility be Measured?

Though the sit and reach test primarily focuses on hamstring extensibility (and is not a reliable measure of lumbar flexibility), it has been used around the world as a basic instrument for measuring baseline flexibility).If patients are interested in establishing their baseline flexibility, consider providing the instructions included at the end of this handout under additional resources. Other measures of flexibility include the zipper test, which evaluates shoulder flexibility, and the sitting-rising test, which may also predict overall mortality risk.

How Can Flexibility Be Developed?

The American College of Sports Medicine recommends that healthy and older adults perform stretching exercises at least 2 days per week, spending about 1 minute on each major muscle tendon group (shoulder girdle, chest, neck, trunk, lower back, hips, posterior and anterior legs, and ankles) for about 10 minutes per session. Many studies have noted benefit in improving range of motion in joints with just 10-30 seconds of stretching on a regular basis. Current literature does not consistently suggest immediate benefit from performing static or dynamic stretching before exercise, but warming up with light aerobic activity and, in some cases, stretching, is still recommended due to the long-term benefits of these activities.

There are many forms of exercise and physical activity that emphasize flexibility. The following is a short list to consider recommending to patients interested in improving their flexibility:

• Yoga - Research supports the use of yoga to increase flexibility.
• Pilates - Research also supports Pilates for increasing flexibility.
• Massage - Many types of massage seek to maintain flexibility of the joints and soft tissues.
• Tai chi - This inner martial art expresses the ideal of strength with flexibility and has been consistently observed to facilitate flexibility.
• Other martial arts - These often work explicitly to develop flexibility.
• Dance - In many forms from around the world, dance is a fun way to stay flexible.
• Gardening - For much of human history, humans have been bending, squatting, and kneeling for horticulture.
• Housework - Depending on how it is done, housework can be a great way to exercise the ability to stretch, bend, and reach.

Keep flexibility in mind as part of a broad-based approach to Moving the Body. Patients may see long-term improvement in range of mtion and muscle power along with other systemic health benefits if engaging in a consistent stretching regimen. 

Heart Rate

Heart rate, or pulse, is how many times your heart beats in a period of time — usually a minute. The usual pulse for an adult is 60 to 100 beats per minute after resting for at least 10 minutes.

Maximum Heart Rate

The maximum heart rate is the fastest your heart can beat.

Target Heart Rate

Your target heart rate is a percentage of your maximum heart rate, which is the fastest your heart can beat. It is based on your age. The activity level that is best for your health uses 50–75 percent of your maximum heart rate. This range is your target heart rate

 National Heart, Lung, and Blood Institute

HRs vary considerably, not only with exercise and fitness levels, but also with age. Newborn resting HRs may be 120 bpm. HR gradually decreases until young adulthood and then gradually increases again with age.

Maximum HRs are normally in the range of 200–220 bpm, although there are some extreme cases in which they may reach higher levels. As one ages, the ability to generate maximum rates decreases. This may be estimated by taking the maximal value of 220 bpm and subtracting the individual’s age. So a 40-year-old individual would be expected to hit a maximum rate of approximately 180, and a 60-year-old person would achieve a HR of 160.

HEART: ABNORMAL HEART RATES

For an adult, normal resting HR will be in the range of 60–100 bpm. Bradycardia is the condition in which resting rate drops below 60 bpm, and tachycardia is the condition in which the resting rate is above 100 bpm. Trained athletes typically have very low HRs. If the patient is not exhibiting other symptoms, such as weakness, fatigue, dizziness, fainting, chest discomfort, palpitations, or respiratory distress, bradycardia is not considered clinically significant. However, if any of these symptoms are present, they may indicate that the heart is not providing sufficient oxygenated blood to the tissues. The term relative bradycardia may be used with a patient who has a HR in the normal range but is still suffering from these symptoms. Most patients remain asymptomatic as long as the HR remains above 50 bpm.

Bradycardia may be caused by either inherent factors or causes external to the heart. While the condition may be inherited, typically it is acquired in older individuals. Inherent causes include abnormalities in either the SA or AV node. If the condition is serious, a pacemaker may be required. Other causes include ischemia to the heart muscle or diseases of the heart vessels or valves. External causes include metabolic disorders, pathologies of the endocrine system often involving the thyroid, electrolyte imbalances, neurological disorders including inappropriate autonomic responses, autoimmune pathologies, over-prescription of beta blocker drugs that reduce HR, recreational drug use, or even prolonged bed rest. Treatment relies upon establishing the underlying cause of the disorder and may necessitate supplemental oxygen.

Tachycardia is not normal in a resting patient but may be detected in pregnant women or individuals experiencing extreme stress. In the latter case, it would likely be triggered by stimulation from the limbic system or disorders of the autonomic nervous system. In some cases, tachycardia may involve only the atria. Some individuals may remain asymptomatic, but when present, symptoms may include dizziness, shortness of breath, lightheadedness, rapid pulse, heart palpations, chest pain, or fainting (syncope). While tachycardia is defined as a HR above 100 bpm, there is considerable variation among people. Further, the normal resting HRs of children are often above 100 bpm, but this is not considered to be tachycardia Many causes of tachycardia may be benign, but the condition may also be correlated with fever, anemia, hypoxia, hyperthyroidism, hypersecretion of catecholamines, some cardiomyopathies, some disorders of the valves, and acute exposure to radiation. Elevated rates in an exercising or resting patient are normal and expected. Resting rate should always be taken after recovery from exercise. Treatment depends upon the underlying cause but may include medications, implantable cardioverter defibrillators, ablation, or surgery.

Generally speaking, a low heart rate when you are at rest indicates that your heart is working efficiently. As you exercise and become more fit, your heart will beat fewer times per minute. The heart is a muscle, after all, and like other muscles it gains strength with regular exercise. This makes its pumping action more efficient. A stronger heart muscle can move more oxygen-rich blood through the blood vessels with each beat, so it does not need to pump as rapidly. It can also rest more between beats.

How to Measure Your Resting Heart Rate

Your resting heart rate is best measured when you first wake up in the morning, even before you get out of bed. To measure your heart rate, place two fingers (your index and middle finger) between the bone and the tendon on the inside of your wrist, below the thumb. You can also feel your pulse just underneath the curve of your jaw bone on your neck. Count the number of times your heart beats in 15 seconds. Multiply this number by 4 for your total beats per minute.

If you have trouble finding your pulse, you can always buy a heart rate monitor, or download one of the many mobile apps that allow you to use your phone as a heart rate monitor.

A normal resting heart rate for adults ranges from 60 to 100 beats per minute. A well-trained athlete, however, might have a normal resting heart rate closer to 40 beats per minute. Talk to your doctor if your resting heart rate is consistently above 100 beats per minute or below 60 beats per minute.

Warm Up/Warming Up

Your physical activity session should start at a slow-to-medium pace to give your body a chance to get ready for more vigorous movement. A warm up should last about 5 to 10 minutes.

National Heart, Lung, and Blood Institute

Flexibility, Warm-Up, and Cool-Down 

Older adults should maintain the flexibility necessary for regular physical activity and activities of daily life. Flexibility activities enhance the ability of a joint to move through the full range of motion. Stretching exercises are effective in increasing flexibility, and thereby can allow people to more easily do activities that require greater flexibility. Although the health benefits of these activities alone are not known and they have not been demonstrated to reduce risk of activity-related injuries, they are an appropriate component of a physical activity program. However, time spent doing flexibility activities by themselves does not count toward meeting the aerobic or muscle-strengthening key guidelines. 

Research studies of effective exercise programs typically include warm-up and cool-down activities. A warmup before moderate- or vigorous-intensity aerobic activity allows a gradual increase in heart rate and breathing at the start of the episode of activity. A cool-down after activity allows a gradual heart rate decrease at the end of the session. Time spent doing warm-up and cool-down activities may count toward meeting the aerobic activity guidelines if the activity is at least moderate intensity (for example, walking briskly to warm up for a jog). A warm-up for muscle-strengthening activity commonly involves doing exercises with less weight.

What Is Multicomponent Physical Activity? 

For older adults, multicomponent physical activity is important to improve physical function and decrease the risk of falls or injury from a fall. These activities can be done at home or in a structured group setting. Many studied interventions combine all types of exercise (aerobic, muscle strengthening, and balance) into one session, and this has been shown to be effective. An example of a multicomponent physical activity program could include walking (aerobic activity), lifting weights (muscle strengthening), and could incorporate balance by walking backwards or sideways or by standing on one foot while doing an upper body muscle-strengthening activity, such as bicep curls. Ballroom dancing also combines aerobic and balance components. 

Water Intake

We all need to drink water. How much you need depends on your size, activity level, and the weather where you live. Keeping track of your water intake helps make sure that you get enough. Your intake includes fluids that you drink, and fluids you get from food.
NIH MedlinePlus

On a typical day, the average adult will take in about 2500 mL (almost 3 quarts) of aqueous fluids. Although most of the intake comes through the digestive tract, about 230 mL (8 ounces) per day is generated metabolically, in the last steps of aerobic respiration. Additionally, each day about the same volume (2500 mL) of water leaves the body by different routes; most of this lost water is removed as urine. The kidneys also can adjust blood volume though mechanisms that draw water out of the filtrate and urine. The kidneys can regulate water levels in the body; they conserve water if you are dehydrated, and they can make urine more dilute to expel excess water if necessary. Water is lost through the skin through evaporation from the skin surface without overt sweating and from air expelled from the lungs. This type of water loss is called insensible water loss because a person is usually unaware of it.

Regulation of Water Intake

Osmolality is the ratio of solutes in a solution to a volume of solvent in a solution. Plasma osmolality is thus the ratio of solutes to water in blood plasma. A person’s plasma osmolality value reflects his or her state of hydration. A healthy body maintains plasma osmolality within a narrow range, by employing several mechanisms that regulate both water intake and output.

A Flowchart Showing the Thirst Response

The thirst response begins when osmoreceptors detect a decrease in water levels in the blood.

Drinking water is considered voluntary. So how is water intake regulated by the body?

Consider someone who is experiencing dehydration, a net loss of water that results in insufficient water in blood and other tissues. The water that leaves the body, as exhaled air, sweat, or urine, is ultimately extracted from blood plasma. As the blood becomes more concentrated, the thirst response—a sequence of physiological processes—is triggered. Osmoreceptors are sensory receptors in the thirst center in the hypothalamus that monitor the concentration of solutes (osmolality) of the blood. If blood osmolality increases above its ideal value, the hypothalamus transmits signals that result in a conscious awareness of thirst. The person should (and normally does) respond by drinking water. The hypothalamus of a dehydrated person also releases antidiuretic hormone (ADH) through the posterior pituitary gland. ADH signals the kidneys to recover water from urine, effectively diluting the blood plasma. To conserve water, the hypothalamus of a dehydrated person also sends signals via the sympathetic nervous system to the salivary glands in the mouth. The signals result in a decrease in watery, serous output (and an increase in stickier, thicker mucus output). These changes in secretions result in a “dry mouth” and the sensation of thirst.

Decreased blood volume resulting from water loss has two additional effects. First, baroreceptors, blood-pressure receptors in the arch of the aorta and the carotid arteries in the neck, detect a decrease in blood pressure that results from decreased blood volume. The heart is ultimately signaled to increase its rate and/or strength of contractions to compensate for the lowered blood pressure.

Second, the kidneys have a renin-angiotensin hormonal system that increases the production of the active form of the hormone angiotensin II, which helps stimulate thirst, but also stimulates the release of the hormone aldosterone from the adrenal glands. Aldosterone increases the reabsorption of sodium in the distal tubules of the nephrons in the kidneys, and water follows this reabsorbed sodium back into the blood.

If adequate fluids are not consumed, dehydration results and a person’s body contains too little water to function correctly. A person who repeatedly vomits or who has diarrhea may become dehydrated, and infants, because their body mass is so low, can become dangerously dehydrated very quickly. Endurance athletes such as distance runners often become dehydrated during long races. Dehydration can be a medical emergency, and a dehydrated person may lose consciousness, become comatose, or die, if his or her body is not rehydrated quickly.

Weight (Body Mass)

 Your weight is the mass or quantity of your heaviness. It is expressed by units of pounds or kilograms.

NIH MedlinePlus

Do you know if your current weight is healthy? "Underweight", "normal", "overweight", and "obese" are all labels for ranges of weight. Obese and overweight mean that your weight is greater than it should be for your health. Underweight means that it is lower than it should be for your health. Your healthy body weight depends on your sex and height. For children, it also depends on your age.

A sudden, unexpected change in weight can be a sign of a medical problem. Causes for sudden weight loss can include

• Thyroid problems
• Cancer
• Infectious diseases
• Digestive diseases
• Certain medicines

Sudden weight gain can be due to medicines, thyroid problems, heart failure, and kidney disease.

Good nutrition and exercise can help in losing weight. Eating extra calories within a well-balanced diet and treating any underlying medical problems can help to add weight.

Playing sports can be fun, but it can also be dangerous if you are not careful. You can help prevent injuries by

• Getting a physical to make sure you are healthy before you start playing your sport
• Wearing the right shoes, gear, and equipment
• Drinking lots of water
• Warming up and stretching

If you have already hurt yourself playing a sport, make sure you recover completely before you start up again. If possible, protect the injured part of your body with padding, a brace, or special equipment. When you do start playing again, start slowly.

Exercising is good for you, but sometimes you can injure yourself when you play sports or exercise. Accidents, poor training practices, or improper gear can cause them. Some people get hurt because they are not in shape. Not warming up or stretching enough can also lead to injuries.

The most common sports injuries are

• Sprains and strains
• Knee injuries
• Swollen muscles
• Achilles tendon injuries
• Pain along the shin bone
• Rotator cuff injuries
• Fractures
• Dislocations

If you get hurt, stop playing. Continuing to play or exercise can cause more harm. Treatment often begins with the RICE (Rest, Ice, Compression, and Elevation) method to relieve pain, reduce swelling, and speed healing. Other possible treatments include pain relievers, keeping the injured area from moving, rehabilitation, and sometimes surgery.

The term “sports injury,” refers to the kinds of injuries that most commonly occur during sports or exercise. Sports injuries can result from:

• Accidents.
• Improper equipment.
• Insufficient warmup and stretching.
• Lack of conditioning.
• Poor training practices.

The most common sports injuries include:

• Muscle sprains and strains.
• Tears of the ligaments that hold joints together.
• Tears of the tendons that support joints and allow them to move.
• Dislocated joints.
• Fractured bones, including vertebrae.

Regardless of the specific structure affected, musculoskeletal sports injuries can generally be classified in one of two ways: acute or chronic.

Acute Injuries

Acute injuries, such as a sprained ankle, strained back, or fractured hand, occur suddenly during activity. Signs of an acute injury include:

• Sudden, severe pain.
• Swelling.
• Inability to place weight on a lower limb.
• Extreme tenderness in an upper limb.
• Inability to move a joint through its full range of motion.
• Extreme limb weakness.
• Visible dislocation or break of a bone.

Chronic Injuries

Chronic injuries usually result from overusing one area of the body while playing a sport or exercising over a long period. The following are signs of a chronic injury:

• Pain when performing an activity.
• A dull ache when at rest.
• Swelling.

What are sports injuries?

Sports injuries are injuries that happen when playing sports or exercising. There are two kinds of sports injuries:

• Acute injuries occur suddenly when playing or exercising. For example:
  • Sprained ankles.
  • Strained backs.
  • Broken bones.
• Chronic injuries happen after you play a sport or exercise for a long time.

Points To Remember About Sports Injuries

• There are two kinds of sports injuries. Acute injuries happen suddenly, such as sprained ankles. Chronic injuries happen after you play a sport or exercise over a long period of time.
• Sports injuries are first treated with R-I-C-E: Rest, Ice, Compression (pressure on the injury), and Elevation (raise the injured area above the heart).
• Doctors will treat more serious injuries with medications, by limiting movement, or by recommending surgery, physical therapy, and rest.
• You can prevent many kinds of sports injuries by following safe exercise habits.

Who gets sports injuries?

Anyone can get a sports injury.

What are the types of sports injuries?

The most common sports injuries are:

• Muscle sprains and strains.
• Knee injuries.
• Achilles tendon injuries.
• Pain along the shin bone.
• Fractures.
• Dislocations.

What are the symptoms of sports injuries?

The symptoms of a sports injury will depend on the type of injury you have.

Symptoms of an acute injury include:

• Sudden, severe pain.
• Swelling.
• Not being able to place weight on a leg, knee, ankle, or foot.
• An arm, elbow, wrist, hand, or finger that is very tender.
• Not being able to move a joint as normal.
• Extreme leg or arm weakness.
• A bone or joint that is visibly out of place.

Symptoms of a chronic injury include:

• Pain when you play.
• Pain when you exercise.
• A dull ache when you rest.
• Swelling.

What causes sports injuries?

The cause of sports injuries can include:

• Accidents.
• Poor training practices.
• Improper gear.
• Being out of condition.
• Not warming up or stretching before you play or exercise.

How are sports injuries treated?

Doctors first treat sports injuries with R-I-C-E (Rest, Ice, Compression, and Elevation).

• Rest. Decrease your regular activities and rest the injured area.
• Ice. Put an ice pack on the injury for 20 minutes, four to eight times per day. You can use a:
  • Cold pack.
  • Ice bag.
  • Plastic bag filled with crushed ice and wrapped in a towel.
• Compression. Put even pressure on the painful area to help reduce the swelling.
• Elevation. Put the injured area on a pillow at a level above your heart.

Your doctor may recommend other things to treat your sports injury.

• Nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen, can help decrease swelling and pain.
• Immobilization is a common treatment for sports injuries. It keeps you from moving the injured area and prevents more damage. To limit movement of your injured area, your doctor may recommend using a:
  • Sling.
  • Splint.
  • Cast.
  • Leg immobilizer.
• Surgery, in some cases, is needed to fix sports injuries. Surgery can fix torn tendons and ligaments or put broken bones back in place. Most sports injuries don’t need surgery.
• Rehabilitation is a key part of treatment. It involves step-by-step exercises that get the injured area back to normal. Rehabilitation may include the following tips:
  • Moving the injured area helps it to heal. The sooner this is done, the better. Exercises start by gently moving the injured body part through a range of motions.
  • The next step is to stretch. After a while, weights may be used to strengthen the injured area.
  • As injury heals, scar tissue forms. After a while, the scar tissue shrinks. This shrinking brings the injured tissues back together. When this happens, the injured area becomes tight or stiff. This is when you are at greatest risk of injuring the area again. You should stretch the muscles every day. You should always stretch as a warmup before you play or exercise.
  • Don’t play your sport until you are sure you can stretch the injured area without pain, swelling, or stiffness. When you start playing again, start slowly. Build up slowly to full speed.
• Rest after an injury is an important part of the healing process. Your doctor can guide you on the proper balance between rest and rehabilitation.
• Other therapies your doctor may recommend include:
  • Electrostimulation, which gives you mild electric shocks.
  • Cold packs.
  • Heat packs.
  • Ultrasound or sound waves.
  • Massage.

Who treats sports injuries?

If you have a severe injury, you need to be seen immediately in an emergency room. Many other sports injuries can be evaluated and treated by your primary doctor.

You may also see:

• An orthopaedic surgeon, a doctor who specializes in diagnosing and treating injuries to bones, joints, ligaments, tendons, muscles, and nerves.
• A physical therapist or physiotherapist, a health care professional who can help you:
  • Develop a rehabilitation program.
  • Strengthen muscles and joints.
  • Prevent further injury.

Can I prevent sports injuries?

These tips can help you avoid sports injuries:

• Don’t bend your knees more than halfway when doing knee bends.
• Don’t twist your knees when you stretch. Keep your feet as flat as you can.
• When jumping, land with your knees bent.
• Do warmup exercises before you play any sport.
• Always stretch before you play or exercise.
• Don’t overdo it.
• Cool down after hard sports or workouts.
• Wear shoes that fit properly, are stable, and absorb shock.
• Use the softest exercise surface you can find; don’t run on asphalt or concrete.
• Run on flat surfaces.

For adults:

• Don’t be a “weekend warrior.” Don’t try to do a week’s worth of activity in a day or two.
• Learn to do your sport right. Use proper form to reduce your risk of “overuse” injuries.
• Use safety gear.
• Know your body’s limits.
• Build up your exercise level gradually.
• Strive for a total body workout of cardiovascular, strength training, and flexibility exercises.

For parents and coaches:

• Group children by their skill level and body size, not by their age, especially for contact sports.
• Match the child to the sport. Don’t push the child too hard to play a sport that she or he may not like or be able to do.
• Try to find sports programs that have certified athletic trainers.
• See that all children get a physical exam before playing.
• Don’t play a child who is injured.
• Get the child to a doctor, if needed.
• Provide a safe environment for sports.

For children:

• Be in proper condition to play the sport.
• Get a physical exam before you start playing sports.
• Follow the rules of the game.
• Wear gear that protects, fits well, and is right for the sport.
• Know how to use athletic gear.
• Don’t play when you are very tired or in pain.
• Always warm up before you play.
• Always cool down after you play.

Your ankle bone and the ends of your two lower leg bones make up the ankle joint. Your ligaments, which connect bones to one another, stabilize and support it. Your muscles and tendons move it.

The most common ankle problems are sprains and fractures. A sprain is an injury to the ligaments. It may take a few weeks to many months to heal completely. A fracture is a break in a bone. You can also injure other parts of the ankle such as tendons, which join muscles to bone, and cartilage, which cushions your joints. Ankle sprains and fractures are common sports injuries.

A concussion is a type of brain injury. It involves a short loss of normal brain function. It happens when a hit to the head or body causes your head and brain to move rapidly back and forth. This sudden movement can cause the brain to bounce around or twist in the skull, creating chemical changes in your brain. Sometimes it can also stretch and damage your brain cells.

Sometimes people call a concussion a "mild" brain injury. It is important to understand that while concussions may not be life-threatening, they can still be serious.

Concussions are a common type of sports injury. Other causes of concussions include blows to the head, bumping your head when you fall, being violently shaken, and car accidents.

Symptoms of a concussion may not start right away; they may start days or weeks after the injury. Symptoms may include a headache or neck pain. You may also have nausea, ringing in your ears, dizziness, or tiredness. You may feel dazed or not your normal self for several days or weeks after the injury. Consult your health care professional if any of your symptoms get worse, or if you have more serious symptoms such as

• Convulsions or seizures
• Drowsiness or inability to wake up
• A headache that gets worse and does not go away
• Weakness, numbness, or decreased coordination
• Repeated vomiting or nausea
• Confusion
• Slurred speech
• Loss of consciousness

To diagnose a concussion, your health care provider will do a physical exam and will ask about your injury. You will most likely have a neurological exam, which checks your vision, balance, coordination, and reflexes. Your health care provider may also evaluate your memory and thinking. In some cases, you may also have a scan of the brain, such as a CT Scan or an MRI. A scan can check for bleeding or inflammation in the brain, as well as skull fractures.

Most people recover fully after a concussion, but it can take some time. Rest is very important after a concussion because it helps the brain to heal. In the very beginning, you may need to limit physical activities or activities that involve a lot of concentration, such as studying, working on the computer, or playing video games. Doing these may cause concussion symptoms (such as headache or tiredness) to come back or get worse. Then when your health care provider says that it is ok, you can start to return to your normal activities slowly.

Your elbow joint is made up of bone, cartilage, ligaments and fluid. Muscles and tendons help the elbow joint move. When any of these structures is hurt or diseased, you have elbow problems.

Many things can make your elbow hurt. A common cause is tendinitis, an inflammation or injury to the tendons that attach muscle to bone. Tendinitis of the elbow is a sports injury, often from playing tennis or golf. You may also get tendinitis from overuse of the elbow.

Other causes of elbow pain include sprains, strains, fractures, dislocations, bursitis and arthritis. Treatment depends on the cause.

Each of your feet has 26 bones, 33 joints, and more than 100 tendons, muscles, and ligaments. No wonder a lot of things can go wrong. Here are a few common problems:

• Bunions - hard, painful bumps on the big toe joint
• Corns and calluses - thickened skin from friction or pressure
• Plantar warts - warts on the soles of your feet
• Fallen arches - also called flat feet

Ill-fitting shoes often cause these problems. Aging and being overweight also increase your chances of having foot problems.