Chapter 2 – Principles of Physical Fitness (Video)
What is Physical Activity and Exercise
Exercise is a planned, structured, repetitive movement explicitly intended to improve or maintain physical fitness. \text{Exercise}
Physical activity is any movement carried out by the skeletal muscles that requires energy; it exists on a continuum with exercise but is broader than formal workouts.
Physical fitness is a set of physical attributes that allow the body to respond or adapt to the demands of physical effort; it supports longevity and health span (the healthy, functional years of life).
Health-related fitness components contribute to wellness and include: \text{cardiorespiratory endurance},\ \text{muscular strength},\ \text{muscular endurance},\ \text{flexibility},\ \text{body composition}.
Exercise benefits vary by fitness and performance ability, but regular physical activity provides many health benefits for everyone. Benefits increase as you move from sedentary to moderate activity and further with higher intensity and duration.
Health Guidelines and Activity Recommendations
The recommended guidelines for adults (health benefits) include:
At least 150\ \text{minutes} per week of moderate-intensity aerobic activity or 75\ \text{minutes} per week of vigorous-intensity aerobic activity, or an equivalent combination.
Any amount of moderate- to vigorous-intensity activity contributes toward the goal.
For more extensive benefits, increase aerobic activity to 300\ \text{minutes} per week of moderate-intensity or 150\ \text{minutes} per week of vigorous-intensity activity, or an equivalent combination.
1 minute of vigorous-intensity training is roughly equivalent to 2 minutes of moderate-intensity training: 1\ \text{min vigorous} \approx 2\ \text{min moderate}.
Muscle-strengthening activities are recommended on two or more days per week, involving all major muscle groups.
Avoid inactivity; otherwise, sedentary behavior increases health risks.
In daily life, any movement counts; break up long periods of sitting with short activity bouts.
Health guidelines stress that some physical activity is better than none, and more activity brings greater health benefits.
Additional context from the guidelines:
The Health and Retirement Study shows higher fitness levels are associated with longer life expectancy and lower death rates: vigorous exercise yielded higher survival rates than moderate or sedentary activity.
Guidelines emphasize both health benefits of activity and improvements in fitness through structured training (exercise) to enhance longevity and health span.
Quantitative examples of moderate-intensity activity that roughly equals about 150 calories in 15–60 minutes include:
Washing a car, 45–60 minutes
Washing windows or floors, 45–60 minutes
Gardening, 30–45 minutes
Pushing a stroller, about 1.5 miles, ~30 minutes
Walking modestly (2 miles, ~30 minutes)
Shoveling snow, 15 minutes
Stair-walking, 15 minutes
See the moderate-intensity column in Figure 2.3 for more examples and calories.
Why Exercise Improves Brain Health
Exercise is described as brain-boosting or "brain food" due to multiple mechanisms:
Endurance and resistance training improve cognitive function (learning, memory, reasoning).
Exercise promotes neurogenesis (creation of new neurons) and supports brain plasticity.
Exercise can offset negative dietary effects on brain health.
Exercise reduces anxiety and depression via endorphin release and other neurochemical changes.
Exercise may delay age-related brain decline, including hippocampal atrophy, and help protect against neurodegenerative diseases such as Alzheimer's.
Even light to moderate activity benefits mental health and cognitive function across the life span, including children and older adults.
Components of Physical Fitness (Health-Related) and Skill-Related Fitness
Health-related components:
Cardiorespiratory endurance
Muscular strength
Muscular endurance
Flexibility
Body composition
Neuromuscular (skill-related) components also influence performance in specific activities:
Speed, Power, Agility, Balance, Coordination, Reaction Time
The purpose of training is to improve these components through specific, well-rounded programs.
Cardiorespiratory endurance is especially important for overall health, and improvements in this area affect energy use, insulin sensitivity, blood pressure, and metabolic health.
Body composition reflects fat mass vs fat-free mass (muscle, bone, water).
Somatotypes (body build) can influence exercise preferences and performance tendencies:
Endomorphs: round/pear-shaped; may excel in weight lifting and cycling, but may struggle with long-distance running.
Mesomorphs: lean and muscular; typically perform well across many activities.
Ectomorphs: thin and linear; light frame can aid endurance activities.
Relative strength is the maximum force per unit body weight or size.
Maintaining muscular strength contributes to healthy aging and can extend life expectancy.
Regular physical activity benefits people of all ages and abilities; genetics and behavior influence fitness potential, but regular activity yields health benefits for everyone.
Basic Principles of Physical Training (Adaptation to Stress)
The body adapts to the physical demands placed on it; improvements come from long-term adjustments (adaptations) to sustained training.
Specificity: to improve a given fitness component, train it specifically; training for one component (e.g., weight training) improves that component more than others (e.g., cardiorespiratory endurance).
Progressive overload: to continue improving, gradually increase training stress (volume or intensity). The overload must be progressed carefully to avoid injury; there are thresholds and safe zones depending on the component and the individual.
Reversibility: fitness gains are reversible; when training stops or declines, fitness declines. Different components reverse at different rates (cardiorespiratory fitness declines more quickly than strength, for example).
Individual differences: people respond differently to training; genetics influence how much improvement is possible and how quickly it occurs.
Training adaptations can be explained with the FITT framework and its extensions: Frequency, Intensity, Time, Type (FITT), plus Volume and Progression (FITT-VP).
A well-designed program balances safety, progression, and individual needs, with attention to rest and recovery.
The FITT-VP Framework for Exercise Design
FITT components:
Frequency: number of training days per week
Intensity: how hard you train (e.g., % of max heart rate, weight loads, etc.)
Time (Duration): how long each session lasts
Type (Mode): the activity type (cardio, strength, flexibility, neuromotor)
Additional factors:
Volume: total amount of exercise, often calculated as Frequency × Intensity × Time
Progression: gradual increases in overload to continue improving
Practical notes:
For endurance, typical recommendations: 3–5 days/week at 20–60 minutes per session; aim for at least 1,000 kcal/week expended, which roughly equals 150 minutes of moderate activity or 75 minutes of vigorous activity.
For muscular strength: resistance training 2–3 days/week; 8–12 repetitions per set; multi-set regimens offer greater benefit if time allows.
For flexibility: stretch major muscle groups 2–3 days/week, hold each stretch 10–30 seconds, 2–4 repetitions per stretch, total ~90 seconds per exercise.
The target heart rate intensity and exact prescriptions for different components are detailed in ACSM guidelines (Table 2.3).
Example of a simple planning approach: a beginner might start with a walk (low-to-moderate intensity) and gradually add short periods of jogging, then intervals, while also incorporating resistance training and flexibility work throughout the week.
The concept of periodization (cycle training) is introduced to vary load and recovery in order to optimize gains and reduce overtraining risk.
Exercise safety and medical screening (PAR-Q+) is emphasized before starting a new program, especially for vigorous activities or in individuals with health risks.
Volume and locomotion details:
For endurance training, target approximately 1,000 kcal per week (or 150 minutes at moderate intensity, or 75 minutes at vigorous intensity).
In resistance training, a common prescription is 1 set of 8–10 exercises, 2–3 days/week, with 8–12 repetitions (older adults: 10–15 reps with lighter weights).
For flexibility, include static stretches of major muscle groups 2–3 days/week.
The overall exercise pyramid depicts three layers of activity: daily lifestyle activity at the base, then moderate-intensity activity and strength/flexibility work, and finally more structured, higher-intensity training on top, with cross-training and variety encouraged.
Designing Your Exercise Program
Key steps to design a safe and effective program:
Medical clearance as needed (PAR-Q+ screening; referral for graded exercise testing if necessary).
Assess current fitness and health status.
Set clear, realistic goals (SMART: Specific, Measurable, Attainable, Realistic, Time-bound).
Choose activities that address all fitness components: cardiorespiratory endurance, muscular strength/endurance, flexibility, and body composition.
Plan a balanced program with progression to avoid stagnation and reduce risk of injury.
Include warm-up and cool-down phases; warm-ups prepare muscles and joints, cool-down aids recovery and circulation.
Build in rest and recovery; avoid overtraining; sleep is essential for recovery.
Consider supervision or guidance from qualified professionals (ACSM, NSCA, ISSA, etc.).
Monitor progress and adjust goals as needed.
Maintain balance with other life activities to prevent burnout.
Important safety notes:
In some individuals, vigorous exercise can trigger risk of sudden cardiac events; risk is lowest around 150 minutes/week (as per guidelines) in healthy adults.
PAR-Q+ is a screening instrument to identify potential safety concerns before starting exercise; a YES to certain items suggests medical clearance is prudent.
In case of fever, illness, or significant symptoms, delay starting or intensifying exercise until recovery.
The role of nutrition and hydration: proper fueling and hydration support recovery and training adaptation; detailed nutrition guidance is covered in later chapters.
The importance of motivation, social support, and coaching:
Working with a partner or trainer can improve adherence and technique.
Trainers should be qualified (ACSM, NSCA, ISSA) and have appropriate background.
Avoid fad programs; focus on evidence-based, sustainable approaches.
Warm-Up, Cool-Down, and Safety Practices
Warm-up: 5–10 minutes of light activity prior to intense exercise; increases blood flow, warms muscles, reduces injury risk. Not the same as static stretching; stretching is best done after warm-up or after the workout when muscles are warm.
Cool-down: gradual reduction in activity after exercise to return blood to resting levels and reduce dizziness or light-headedness; includes light activity and gentle stretching.
Practical safety measures:
Wear appropriate protective gear (helmet, eye protection, reflective gear).
Exercise with a partner or in well-lit, populated areas.
Use proper technique; avoid lifting beyond your capacity; ensure equipment is in good condition.
Hydrate adequately and fuel appropriately to support training sessions.
Overcoming Barriers to Being Active
Lab 2.2 identifies common barriers and provides strategies to overcome them. Barriers include:
Lack of time
Social influences
Lack of energy
Lack of willpower
Fear of injury
Lack of skill
Lack of resources
Scoring from the barriers quiz helps identify which barriers are most important for you; strategies are provided to address each barrier (e.g., scheduling, social support, simple activities, progressive skill-building, affordable options).
Additional barrier categories include weather, travel, retirement, family obligations.
Using a Fitness Tracker or Smartphone App to Measure Activity (Lab 2.3)
Baseline measurement: use a fitness tracker or smartphone app for a week to establish average daily steps, distance, and flights of stairs.
Set goals based on guidelines:
At least 150 minutes of moderate activity per week.
60 minutes of moderate-to-vigorous activity most days to manage weight.
60–90 minutes daily for weight maintenance or loss.
Break goals into mini-goals (e.g., increase daily steps by 2,000 with weekly progress increments).
Develop strategies to increase daily activity (e.g., walk more, take stairs, park farther away, walk during breaks, use walkable routes).
Track progress weekly and adjust plans as needed; consider visualizing progress with graphs.
The Activity Pyramid and Program Tiers (Figure 2.5)
Four levels of activity / health benefits:
Lifestyle physical activity (daily movement such as walking, stairs, chores) – baseline benefits.
Moderate-intensity aerobic exercise (e.g., 150–300 minutes/week) plus resistance training and flexibility.
Vigorous-intensity exercise or interval training (more intense workouts with possible HIIT, higher adaptation potential but higher injury risk).
High-volume or highly structured programs for advanced goals; include cross-training to reduce injury risk.
A practical takeaway: aim for a mix of daily movement, regular moderate activity, and periodic higher-intensity sessions, adjusting to your goals and safety.
Exercise and Cardiorespiratory Endurance: A Closer Look (Component Details)
Cardiorespiratory endurance is the ability to perform prolonged, large-muscle, dynamic exercise at moderate to high intensity.
Benefits and adaptations include:
Increased stroke volume (more blood per heartbeat)
Improved oxygen delivery and utilization
Reduced resting heart rate and improved blood volume
Better thermoregulation, blood vessel pliability, and metabolic efficiency
Enhanced antioxidant systems and reduced oxidative stress
Practical tip: Treat cardiorespiratory fitness as a core pillar; schedule regular endurance work as the base of most programs.
Neuromuscular and Skill-Related Fitness (Context and Training)
In addition to health-related fitness, sport- or activity-specific skills depend on neuromuscular fitness:
Speed, Power, Agility, Balance, Coordination, Reaction time
These are often developed through practice of the specific movement and can be enhanced by focusing on neuromuscular training (e.g., balance and proprioception exercises; yoga, tai chi for older adults).
Diversity and Disability in Fitness
Fitness and athletic achievement are not limited to those without disabilities (Diversity Matters):
Paralympics demonstrate high levels of fitness and performance among athletes with disabilities.
Approximately 67 million Americans have some type of chronic disability; inclusive programs and adaptive equipment enable participation across ages and abilities.
Guidelines emphasize equal access and reasonable modifications to ensure participation in physical education and sport; seek professional medical advice when needed.
The Design Principles of Physical Training (Adaptation Theory) – Detailed Overview
Specificity: training should be matched to the desired goal and the specific body parts or skills involved.
Progressive overload: to improve, you must gradually increase stress; there are safe thresholds and zones.
Volume and progression concepts:
Volume V = Frequency × Intensity × Time (F × I × T)
Progression means gradually increasing overload and adjusting to the body’s response to training.
Reversibility: the body reverts toward baseline if training stops; train regularly to maintain gains.
Individual differences: genetics influence the potential for adaptations and the rate of improvement.
Practical guidance:
Beginners should start at the lower end of beneficial zones and progress gradually.
Avoid increasing frequency, intensity, and time all at once; progress incrementally.
Use periodization to cycle through phases of higher intensity and lower intensity to facilitate recovery.
The ACSM guidelines and the FITT-VP framework provide structured recommendations for different fitness domains (cardio, strength, flexibility) and emphasize a balanced, progressive approach.
Medical Screening, Safety, and Program Start (PAR-Q+ Lab 2.1)
PAR-Q+ is a screening tool used to determine safety for increasing physical activity; if you answer YES to any follow-up questions, seek medical advice or an online/ePARmed-X+ assessment.
Categories covered in the PAR-Q+ follow-up:
Arthritis or back problems
Cancer
Heart or cardiovascular conditions
High blood pressure
Metabolic conditions (diabetes, etc.)
Mental health issues
Respiratory diseases
Spinal cord injuries
Stroke or TIA
Other medical conditions
The PAR-Q+ process emphasizes obtaining medical clearance when risk factors exist and using an informed, individualized plan.
If you answer NO to all follow-ups, you can proceed with activity but still consider a professional assessment for personalized guidance.
Overcoming Barriers to Being Active (Lab 2.2)
Barriers quiz identifies seven main barrier categories:
Lack of time
Social influence
Lack of energy
Lack of willpower
Fear of injury
Lack of skill
Lack of resources
Scores help identify which barriers are most important for you; strategies are provided to address each barrier (e.g., schedule, social support, skill-building, low-cost options).
Additional barriers include weather, travel, retirement, family obligations. Practical strategies cover home-based options, indoor alternatives, and community resources.
Practical Tools for tracking and goal-setting (Lab 2.3)
The use of fitness trackers and smartphone apps helps quantify activity: steps, distance, flights of stairs, heart rate, and workout metrics.
Goals to aim for (SMART) and actionable mini-goals help sustain motivation.
The resources emphasize finding realistic goals and tracking progress to sustain adherence.
Common Questions and Useful Guidance
If you have asthma: start gradually and consult a doctor to tailor activity types and intensities.
Goals should be based on overall health aims (reducing disease risk, increasing energy, maintaining healthy weight) and informed by labs (Chapters 3–6) for precise targets.
Vaccination and public health context (boxed in the chapter): vaccines (e.g., COVID-19) are highly beneficial for public health; individual decisions should consider risk-benefit analysis and rely on trustworthy sources.
For people with disabilities or chronic conditions, adaptions and supportive programs enable safe exercise and health benefits.
Boxed Topics and Their Implications
Vaccine Hesitancy: A health context box detailing safety, efficacy, and societal implications of vaccines, including:
Adverse event rates for vaccines (e.g., ~0.006% for a severe adverse event in Covid-19 vaccination among those who were vaccinated).
Large-scale vaccination coverage statistics (e.g., 81% have received at least one dose; 70% fully vaccinated).
The role of misinformation, trust in healthcare systems, and the importance of credible information.
Ethical considerations: balancing individual autonomy with collective health benefits; historical contexts (e.g., Tuskegee) shaping trust.
The box emphasizes that vaccines are a major public health achievement and that vaccination reduces risk of severe outcomes, with practical considerations for individuals and communities.
Diversity Matters: Fitness and Disability – emphasizes inclusion, accessibility, and adaptive strategies to ensure participation for people with disabilities.
Fitness Center Selection: Guidance on evaluating facilities for safety, staff qualifications, equipment, and accessibility; the importance of orientation and credible certification (ACSM, NSCA, ISSA, ACE, etc.).
Critical Consumer: Exercises caution in selecting trainers and facilities; beware of fad programs; look for evidence-based practices and qualified professionals.
Speficial Formulas and Quantitative Details (LaTeX)
Weekly guidelines (health benefits):150\,\text{minutes (moderate)} \leq \text{per week} \,\text{or}\, 75\,\text{minutes (vigorous)}
Equivalent:1\,\text{min vigorous} \approx 2\,\text{min moderate}
Volume (endurance) target:V = f \times I \times t \approx 150\ \text{min/week (moderate)} \; \text{to} \; 300\ \text{min/week (more benefits)}
Caloric volume example:1{,}000\ \text{kcal/week} \ \text{(endurance)}; equivalently, the duration could be 75\ \text{min/week (vigorous)} or other combinations that yield the same energy expenditure.
Resistance training recommendations:1\ \text{set} \times 8\text{–}12\ \text{reps} \times \text{major muscle groups}; older adults: 10\text{–}15\ \text{reps} with lighter weights.
Warm-up and cool-down durations: indicated for optimizing safety and recovery, with the warm-up preceding the main session and cool-down following.
The 60–90 minutes/day range for intensive weight management goals is discussed in weight-management guidelines.
Summary Takeaways
Moderate daily physical activity contributes substantially to health; more activity yields greater health benefits.
The five health-related fitness components (cardiorespiratory endurance, muscular strength, muscular endurance, flexibility, body composition) are central to wellness.
Training improves fitness through adaptation to stress; specificity and progressive overload guide targeted improvements.
Reversibility, individual differences, and safe progression mean plans should be tailored, monitored, and adjusted.
A well-designed program includes assessment, goal-setting, progressive overload, warm-up/cool-down, safety considerations, and strategies for adherence.
Regular physical activity benefits brain health and mental health across the lifespan.
Diversity and inclusion in fitness programs ensure opportunities for people with disabilities or different backgrounds to participate.
Digital tools can aid motivation and tracking, but success hinges on consistent use, realistic goals, and integration into daily life.
When starting a program, prioritize safety, informed decision-making, and balanced development of all fitness components; seek professional guidance as needed.
Key Formulas and Tables Referenced (Names and Content)
Table 2.1: Examples of moderate- and vigorous-intensity activities and their calories per duration; Table 2.2: General guidelines for exercise for health, weight management, muscle strength, flexibility, and neuromuscular training; Table 2.3: ACSM exercise recommendations for fitness development (cardiorespiratory, muscular, neuromotor, flexibility).
Figure 2.2: Added years of life with higher cardiorespiratory fitness; Figure 2.1: Relative risk of death decreases with increased activity.
Figure 2.3: Examples of moderate-intensity activities that use about 150 calories (caloric expenditure varies with duration and intensity).
Figure 2.4: Physical activity pyramid (Sedentary activities, Strength training, Cardiorespiratory endurance, Moderate-intensity activity, and Overall daily activity).
Figure 2.5: Health and fitness benefits of different activity levels (lifestyle activity, moderate program, vigorous program, and higher-volume programs).
Box: TAKE CHARGE Move More, Sit Less – strategies to reduce sedentary time and fit activity into daily life.
Box: Vaccine Hesitancy – risk/benefit data, trust and misinformation issues, and public health implications.
Box: DIVERSITY MATTERS Fitness and Disability – inclusion strategies and adaptive resources.
LAB 2.1 PAR-Q+ Safety of Exercise Participation – the follow-up questions and scoring to determine safety and need for medical clearance.
LAB 2.2 Overcoming Barriers to Being Active – a structured set of strategies for common barriers.
LAB 2.3 Using a Fitness Tracker or Smartphone App – baseline, goal setting, mini-goals, and progress-tracking templates.
If you’d like, I can tailor these notes further to target specific exam topics or convert them into a more compact study guide. Also, I can export this as a PDF if needed.