The concepts of physical activity, exercise, sport, health, wellness and fitness are introduced in this Chapter. Physical activity, exercise or participation in a sport helps an individual to attain or maintain physical fitness. Physical fitness is the ability of the body to tolerate physical stress. Physical fitness is of two types: health-related and performance-related. The factors that can influence physical fitness are heredity, lifestyle, physical, social and psychological environment, and also personal attributes. The health benefits of physical activity/exercise are immense and regular exercise or being active is the key to health. The benefits of exercise or physical activity depend on the type, duration and intensity of exercise. Every individual should try to be active daily and must do at least 30 minutes of exercise/activity for five times in a week to attain health and fitness. Optimal nutrition is the base of achieving health, physical fitness and excellence in sports.
Human body is designed for activity and can adapt to a wide range of metabolic demands imposed by physical activity or exercise. Evolution teaches us that early humans could not have survived without the ability to perform very demanding physical work. Yet, in the current times the physical activity levels of humans have declined greatly due to increased automation, changed working patterns and lifestyle.
“Lack of activity destroys the good condition of every human being, while movement and methodical physical exercise save it and preserve it”—Plato (427–347 BCE)
Physical inactivity is also termed as “sedentary death syndrome” and is associated with chronic degenerative diseases (cardiovascular disease, diabetes mellitus, cancer, obesity, hypertension, osteoporosis and depression) and premature death. Physical inactivity is a modifiable risk factor. Individuals can adopt an active lifestyle; play a sport or exercise regularly to improve health and fitness.
“Positive health requires knowledge of man's primary constitution and of the powers of various foods, both those natural to them and those resulting from human skill”—Hippocrates (480 BC)
Similarly, good nutrition is inevitable to attain health, fitness, and excellence in sport. Appropriate diet helps to prevent illness, lowers the risk of chronic degenerative diseases and also helps athletes to excel in sports.
This chapter introduces you to the basics of physical activity, exercise, health, fitness and sports, while explaining the importance of being active and perform regular exercise to attain lifetime health and fitness. The precise role of nutrition in active lifestyle is also discussed.
PHYSICAL ACTIVITY, EXERCISE AND SPORT
Physical activity is defined as any body movement produced by skeletal muscle that results in energy expenditure and produces progressive health benefits (e.g. occupation, household chores, leisure time activities and sport).
Physical inactivity is an extremely inactive lifestyle characterized by excessive sitting all throughout the day, a level of activity lower than that is required to maintain good health.
Exercise is a subset of physical activity that is planned, structured, and repetitive and has the objective of improving or maintaining physical fitness, health performance and appearance. Table 1.1 explains the various elements of physical activity and exercise.
It is necessary to understand the difference between physical activity and exercise in order to decide the life style modifications required to attain health.
Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.2 Health has both positive and negative dimensions. Positive health is associated with a capacity to enjoy life and to withstand challenges; it is not merely absence of disease. Negative health is associated with morbidity and in the extreme with premature mortality.3 Many a time's health is synonymously used to wellness. But, Wellness is an active process of becoming aware of and making choices towards a healthy and fulfilling life.
The concept of physical fitness: When physical activity becomes more organized and goal oriented, it may be referred to as sport. Physical activity, exercise and sport help to attain or maintain physical fitness. Sport is defined as any organized activity that involves exercise, follows rules and has an element of competition. Sports can be broadly classified as power/strength, endurance, skilled, esthetic and team sports (Table 1.2). Every sport is unique, uses different energy systems, and requires varied training, fitness and nutritional needs.
Physical fitness is a state of bodily function that is characterized by the ability to tolerate physical stress. The stress could be as simple as climbing the stairs or a strenuous workout at the gym. Fitness for an individual is the ability to perform a given physical task with ease in a specified physical, social and psychological environment. WHO (1968)8 defines physical fitness as the ability to perform muscular work satisfactorily. It is the capacity to carry out tasks with vigor and alertness, without undue fatigue and with ample energy to enjoy pursuits and meet unexpected emergencies.
Physical fitness appears to be similar to physical activity in its relation to morbidity and mortality, but is more strong predictive of health outcomes than physical activity.9 Hence, fitness can be described as health related and performance related fitness.
Health-related fitness is defined as a state characterized by the ability to perform daily activities with vigor; and by traits and capacities that are associated with a low risk of developing chronic diseases and premature death.10 The fitness components are classified as cardiorespiratory, metabolic, muscle strength and endurance, motor and morphological fitness (Table 1.3).
Performance-related fitness refers to those components of fitness that are essential for optimal work and sports performance. It is defined in terms of individual's ability in athletic competition. Performance-related fitness depends on motor skills, cardiorespiratory power and capacity, muscular strength and power or endurance, body size and composition, motivation and nutritional status11 (Table 1.4).
THE PARADIGM: PHYSICAL ACTIVITY AND HEALTH
The benefits of exercise and physical activity on health and fitness are well recognized. There exists a graded linear relation between the volume of physical activity and health status as seen in Flowchart 1.1.
Flowchart 1.1: Relationship between physical activity, health-related fitness and health status.11
However, there are various other confounding variables that influence health and fitness as genetics, lifestyle, physical and social environmental conditions and personal attributes (Nutrition spotlight).
Health benefits of physical activity and exercise:
Exercise plays a major role in primary as well as secondary prevention of various chronic degenerative diseases. Here we discuss in detail the indisputable benefits of physical activity and exercise:
- Body weight and composition: Physical activity or exercise promotes weight loss in overweight and obese persons; and also helps to maintain ideal body weight and composition in both athletes and non-athletes.
- Musculoskeletal fitness: Exercise improves musculoskeletal fitness, muscle tone, strength, endurance and flexibility, body posture and physical appearance. Improved musculoskeletal fitness with exercise is particularly important for aging population. It is positively associated with functional independence, mobility, glucose homeostasis, bone health, psychological well-being and overall quality of life.
- Bone health: High impact/weight-bearing/resistance exercise increases bone mineral density and reduces the risk of osteoporosis and fractures. Intervention of regular exercise training prevents or reverses bone loss in postmenopausal women.
- Cardiovascular health: Exercise improves and strengthens the cardiovascular and respiratory systems. Exercise can attenuate or reverse the disease process in symptomatic as well as asymptomatic patients with cardiovascular disease. It reduces serum triglycerides and increases high density lipoprotein (HDL) cholesterol levels. Exercise also prevents rise in blood pressure, reduces systemic inflammatory markers such as C reactive protein, decreases blood coagulation, improves coronary blood flow and reduces plaque formation in heart patients.
- Diabetes: Both resistance and aerobic exercise can prevent or delay the incidence of type 2 diabetes mellitus especially in those with increased risk. Exercise intervention is also effective in the management of diabetes. It improves cellular glucose sensitivity by increasing the activity of glycogen synthase and hexokinase; improving muscle capillary density and glucose delivery to the muscles.
- Cancer: Exercise reduces the incidence of breast and colon cancer in women. Exercise, increases energy expenditure, regulates sex hormone levels, improves immunity, and reduces free radical generation and consequently tumor formation. Exercise can also improve the overall quality of life and health status of patients with cancer. Further research is necessary to examine its role in prevention of cancer.
- Cognition and psychological well-being: Exercise increases serotonin in the brain which helps maintain mental health. Exercise increases circulating neurotrophin such as brain-derived neurotrophic factor (BDNF) that helps to alleviate depression. Furthermore increase in the levels of endorphins, epinephrine, serotonin and dopamine with exercise relieve pain, elevate mood and reduce anxiety. Exercise also improves the cognitive function and delays incidence of dementia.Exercise plays an important role in psychological well-being of individuals. Research suggests that exercise can be effectively used to treat anxiety, stress, mood swings, and premenstrual depression. It also helps to improve individuals’ self-esteem and body image.
- Sleep disorders: Exercise training helps individuals sleep better, improves sleep quality in individuals with obstructive sleep apnea.
- Immunity: Regular exercise or physical activity improves resistance to infections.
- Quality of life: Physical activity improves quality of life and physically fit individuals feel healthy and lead a happy life.
PHYSICAL ACTIVITY GUIDELINES
Benefits of exercise depend on the type and intensity of the activity. The types of exercise are classified on the basis of extent of muscle contraction and predominance of energy system.
Types of Exercise
- Exercise based on resistance or extent of contractile activity
- Endurance means prolonged continuous or intermittent periods of contractile activity against low resistance. It increases breathing and heart rate for an extended period of time, e.g. walking, jogging, swimming, sweeping, dancing and playing tennis.
- Resistance or strength exercise involves short periods of contractile activity against high resistance. These exercises build muscle, and even small changes in muscle strength can make a real difference in the ability to perform daily activities, e.g. weightlifting.
- Sprint exercise consists of short periods of maximal contractile activity against low resistance, e.g. competitive 50 meter swim.
- Exercise based on predominance of energy system
- Aerobic exercise derives energy mainly from biochemical processes that require oxygen directly or indirectly.
- Anaerobic exercise derives energy from processes that do not require oxygen.
Endurance exercise is aerobic and also termed as cardiorespiratory exercise, while resistance and sprint exercises are anaerobic.
Intensity of Exercise
Intensity of activity/exercise is the ability to perform physical work and is dependent on the ability of the muscle to transform chemical energy into mechanical energy. The intensity of exercise determines the amount of energy expended and energy substrate required. The relative intensity of exercise is quantified in terms of oxygen consumption (VO2 max), heart rate (HR), rate of perceived exertion (RPE) and metabolic equivalents (METs). Each of these methods has strengths and limitations. A person is rarely able to describe his/her intensity of exercise or activity.
However, a sports/exercise nutritionist needs to be aware of these concepts to understand the extent of individuals’ exercise to determine nutritional requirements. In depth details of these methods are beyond the scope of this book. But brief details on the quantification and levels of intensity of exercise are explained below (Table 1.5).
Quantification of intensity of exercise:
- VO2 max: VO2 max is the maximum capacity of an individual's body to transport and use oxygen during exercise and reflects individual's physical fitness. The relative rate of oxygen consumption is expressed as mL/kg/min.
- Heart rate (HR): The increase in heart rate is proportional to intensity. Maximal HR is estimated by subtracting age from 220 (220-Age). For example, the maximal heart rate for a 20y individual equals to 200, i.e. 220-20. It can be easily monitored using a monitor or recording the pulse for a minute.
- Rate of perceived exertion (RPE): RPE is measured by asking the person to rate how they feel while performing an activity. It is a psychological parameter linked to many physiological events that occur during exercise. The scale is valid and it generally evidences a linear relation with both heart rate and oxygen uptake during aerobic exercise. It is simple and user friendly. The Borgs Rating of Perceived Exertion (RPE) is widely used to determine the exertion.13 It is a 1–20-point scale but is now modified to 1–10-point scale (Table 1.6).
Physical Activity Guidelines for Indians
Research on exercise, physical activity, sports and physical fitness on Indians is limited. The American College of Sports Medicine (ACSM), American Heart Institute and US Department of Health and Human Services (2008)12 recommends at least 150 minutes (2 hours and 30 minutes) of moderately intense physical activity per week for healthy adults. The Consensus Physical Activity Guidelines for Asian Indians recommends a total of 60 minutes of physical activity including 30 minutes of moderate-intensity aerobic activity, 15 minutes of work-related activity, and 15 minutes of muscle strengthening activity in view of the high proneness to Type 2 diabetes and coronary heart disease. The exercise guidelines for athletes are different and aim at enhancing performance related fitness components with the help of sports specific training.
The guidelines aim at reducing the risk of chronic degenerative diseases and promote health-related fitness (see Table 1.2) particularly cardiovascular and muscular fitness which is possible due to the various exercise induced metabolic alterations in working muscles as well as other organs and tissues such as liver and adipose tissues. The rate of metabolism is increased during physical activity and may remain elevated for hours or days. The alterations depend on many factors, viz. types of exercise, intensity and duration of exercise.15
Physical Activity Guidelines for Indians of Varied Age Groups
Healthy adults must adopt and follow these activity guidelines to prevent illness and attain good health and fitness. Children and adolescents need to be active to ensure proper growth and development. Along with increase in physical activity children must restrict their leisure time television/computer viewing to less than 2 hour per day. Schools should give more time for active participation in sports and help inculcate active lifestyle among children. Pregnant women with uncomplicated pregnancy can exercise throughout and also begin to exercise as soon as practicable following the birth of the baby. Senior citizens should initiate exercise in consultation with a physician if they have not exercised before. The activity recommendations for them are similar to healthy adults. Resistance training is particularly beneficial to improve strength and physical functioning (Fig. 1.1).
Table 1.7 elaborates the physical activity guidelines for varied age groups and pregnant women. The activity guidelines are compiled by the authors on the basis of FITT principle. FITT stands for frequency, intensity, type and time or duration of exercise; and guides individuals to exercise for achieving health and fitness.
Safety Concerns in Exercise and Physical Activity
Any individual who wants to start with an exercise regimen or routine must take into consideration the following aspects.
- Physical activity should be in accordance to individuals fitness level and health goals.Fig. 1.1: Physical activity pyramid.Source: ACSM guidelines for physical activity for illustration purpose.15
Table 1.7 Physical activity guidelines for Indians.9,14,16Age groupFrequencyIntensityTypeTimeNoteChildren and adolescents(5–17 years)Preferably dailyModerate or vigorousHopping, jumping, skipping, swimming, cycling, dancing60+ min/dSports oriented activities are most suitable childrenAt least 3 days/weekMuscle strengtheningClimbing trees, weights, playing on playground equipment20–30 min/dActive transport over and above habitual physical activityAt least 3 days/weekBone strengtheningRunning, jumping rope, basketball, tennis, etc.20–30 min/dTelevision viewing and computer restricted to less than 2 hr/dHealthy adultsDailyModerately intense aerobic activityBrisk walking, jogging, hiking, gardening, bicycling30 min/dBrisk walking preferred initial mode of exerciseWork-related activityClimbing stairs, walking during breaks15 min/dFor health benefits—moderately intense aerobic activity< 300 min/weekVigorous intensity <150 min/weekMuscle strengthening activityWarm up, stretching of upper and lower body limbs, and weight training using lightweights15 min/dPregnancyDailyModerate intensityWalking, cycling, swimming30 min/dConsult the doctorIn absence of contraindications, exercise is recommended and safe throughout pregnancySenior citizens(age above 60 years)Daily(a) Moderately intense aerobic activity(b) Muscle strengthening exerciseSame as healthy adultsWeight training using light weights30 min/d15 minAerobic activity has an inverse dose response relationship with major chronic diseases (cardiac disease, type 2 diabetes, depression, cancer, dementia, disabilities)Resistance exercise is recommended to improve strength and physical functioning
- Exercise or physical activity should be gradually increased to meet health goals
- Use appropriate clothing and sports equipment and exercise in safe environment, make sensible choices as to when, where and how to be active.
- Exercise under close supervision of a healthcare provider if an individual has severe chronic conditions or symptoms.
- Ensure adequate hydration prior to physical activity. During physical activity/exercise, fluids should be consumed frequently in an amount sufficient to compensate losses in sweat. The maximal amount of fluid should be comfortably tolerated without causing any gastrointestinal discomfort.
NUTRITION FOR SPORTS, EXERCISE AND FITNESS
Nutrition, the science of food goes hand in hand with exercise and fitness. If an individual is physically active or on an exercise regimen he/she should consume the right blend of foods to support exercise and remain fit. It appears prudent for all to understand the basics of food, nutrition and diet to support activity, exercise, sports and health. A brief description on certain relevant terms is given below. But in depth scientific information on energy and nutrient requirements is given in the subsequent chapters.
Food is that which nourishes the body. It is also defined as anything that is eaten or drunk which meets the need for energy, building, regulation and protection of the body. Food is the raw material of our body. Intake of the right amounts and type of nutrients ensures good nutrition and health.
Nutrition is defined as food at work in the body. Nutrition is the intake of food, considered in relation to the body's dietary needs. It is everything that happens to food from the time it is eaten until it is used for various functions in the body.
Nutrients are components of food that are needed by the body in order to grow, reproduce and lead a normal healthy life. Nutrients include water, carbohydrates, fats, proteins, vitamins and minerals.
Balanced diet is the one which contains different types of foods in quantities and proportions that the need for energy, protein, carbohydrates, fats, vitamins and minerals is adequately met and a small provision is made for extra nutrients to withstand short duration of leanness.
Adequate, optimum and/or good nutrition indicates adequate supply of essential nutrients in correct proportion. It also implies that the nutrients are utilized in the body to the highest level in order to achieve and maintain physical and mental health throughout life.
Nutrients are of two types: macronutrients and micronutrients.
Macronutrients are defined as those macromolecules present in plant and animal structures that can be digested, absorbed, and utilized by another organism as energy sources and as substrate for the synthesis of the carbohydrates, fats and proteins required to maintain cell and system integrity.
Micronutrients are nutrients required in small quantities and essential for effective regulation of metabolic processes in the body. Micronutrients include vitamins and minerals.
Vitamins are organic substances that have crucial role in almost all bodily processes and must be obtained from food or dietary supplements.
Vitamins are classified as water soluble and fat soluble. Water soluble vitamins are thiamin, riboflavin, niacin, folic acid, pantothenic acid, biotin and vitamin B12 (cobalamin). Fat soluble vitamins are A, D, E and K. The functions of vitamins are listed here and the recommended dietary allowance (RDA) for vitamins is discussed elsewhere. The requirement of vitamins and minerals could be increased in physically active individuals.
Minerals are constituents of enzymes, hormones, and vitamins. Minerals are either bound to other chemicals such as calcium phosphate or available ionic form in body fluids. Minerals required in amounts higher than 100 mg/d are macrominerals (calcium, phosphorus, potassium, sodium and magnesium) and those required less than 100 mg/d are microminerals (iron, fluorine, zinc, copper, selenium, iodine and chromium).
Water is vital to life. Body cannot carry out most of its activities without water. It is abundant in the body and amounts to 40–70% of body weight. The water content in the body varies with age, gender and body composition. It constitutes 65–75% of muscle mass and about 50% of adipose tissues. Water, does not provide energy but must be consumed in sufficient amounts to replace the amounts lost—a balance between intake and output should be maintained. Water is a universal solvent, transports biomolecules, facilitates cellular reactions, acts as a lubricant, regulates body temperature and maintains acid base balance.
The precise functions, recommended dietary allowances (RDA) and sources of macro and micronutrients is explained in detail in upcoming chapters.
- Explain the difference between physical activity, exercise and sport.
- Classify the different sports.
- Discuss in detail the health related components of fitness.
- Explain in detail the benefits of exercise.
- Differentiate between resistance and endurance exercise.
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