Introduction to Movement Behaviors and Physical Activity

Exam Tip: Remember that physical activity and sedentary behavior are distinct constructs. You can meet the guidelines for physical activity (e.g., a 30-minute run) and still be considered "sedentary" if you spend the remaining 9.6 hours of your day sitting.

Components of Physical Fitness

To optimize health and performance, we focus on three key areas of fitness:

1. Cardiorespiratory Fitness

This describes the ability of the heart, lungs, and blood vessels to function efficiently. It is often assessed using $VO_{2max}$, which estimates the body's maximum ability to take in and use oxygen during exercise.

2. Muscular Strength and Endurance

Muscular strength is the maximum amount of force a muscle can exert in a single contraction (often measured by a one-repetition maximum, or 1RM). Muscular endurance is the ability of a muscle to exert force repeatedly without fatiguing, such as performing multiple push-ups.

3. Flexibility

Flexibility refers to the range of motion available at a joint or series of joints. It is categorized into static flexibility (the limit of a joint's range of motion in a held position) and dynamic flexibility (the ease of movement during active tasks).

Planning Your Program: The FITT Principle

When designing a structured fitness program, you can use the FITT principle to ensure you are targeting your goals effectively:

• Frequency: How often you exercise (e.g., 3–5 times per week for cardiorespiratory health).
• Intensity: How hard you work (e.g., light, moderate, or vigorous).
• Time: How long each session lasts (e.g., 20–30 minutes).
• Type: The kind of activity you choose (e.g., swimming for cardio or weightlifting for strength).

Worked Example: Calculating Target Heart Rate To find your target heart rate for moderate-to-vigorous activity, first calculate your Maximum Heart Rate (MHR):

$\text{MHR} = 220 - \text{age}$

If you are 20 years old: $\text{MHR} = 220 - 20 = 200 \text{ bpm}$

For a vigorous intensity target (75–90% of MHR): $\text{Lower Bound} = 200 \cdot 0.75 = 150 \text{ bpm}$ $\text{Upper Bound} = 200 \cdot 0.90 = 180 \text{ bpm}$

Your target range would be 150–180 beats per minute.

Understanding Sedentary Behavior

Sedentary behavior is any waking behavior characterized by an energy expenditure of less than 1.5 METs (metabolic equivalents) while in a sitting, reclining, or lying position. Common examples include watching TV, using a computer, or sitting during a commute.

It is important to note that high levels of sedentary time are associated with increased risks of obesity, type 2 diabetes, cardiovascular disease, and even neck or back pain. While increasing physical activity is beneficial, reducing sedentary time is a separate, equally important goal for improving health outcomes.