PE36: Sedentary Lifestyle and Obesity

🛋️ What is a Sedentary Lifestyle?

Examples of sedentary behaviour:

• Sitting at a desk or computer for long periods (office work, school)
• Watching television or streaming for several hours daily
• Playing video games or using phones/tablets for extended periods
• Using motorised transport instead of walking or cycling
• Choosing inactive leisure activities over active ones

⚠️ Consequences of a Sedentary Lifestyle

A sedentary lifestyle has serious health consequences that affect multiple body systems:

Obesity

• Low energy expenditure combined with high calorie intake leads to weight gain
• BMI exceeds 30, classifying the person as obese
• Excess body fat accumulates from unused energy (calories)
• Reduced metabolic rate from inactivity makes weight gain easier

Coronary Heart Disease (CHD)

• Lack of exercise weakens the heart muscle
• Inactivity contributes to high blood pressure and high cholesterol
• Fatty deposits (atheroma) build up in coronary arteries
• Increased risk of angina, heart attacks and heart failure

Hypertension (High Blood Pressure)

• Sedentary behaviour is a major risk factor for high blood pressure
• The heart must work harder to pump blood through less elastic blood vessels
• Increases the risk of stroke, kidney damage and heart disease

Type 2 Diabetes

• Physical inactivity reduces insulin sensitivity
• Excess body fat (especially visceral fat) increases insulin resistance
• Blood glucose levels become harder to regulate
• Can lead to serious complications including nerve damage and vision loss

Osteoporosis

• Weight-bearing exercise stimulates bone formation and maintains bone density
• Lack of mechanical stress on bones causes them to become weak and brittle
• Increased risk of fractures, especially in older adults
• Particularly affects the hips, spine and wrists

Muscle Atrophy

• Muscles that are not used regularly decrease in size and strength
• Loss of muscle mass reduces metabolic rate, making weight gain easier
• Reduced strength makes everyday tasks more difficult
• Poor posture and increased back pain from weak core muscles

⚖️ Obesity and BMI

Causes of Obesity

• Energy imbalance: Consuming more calories than are expended through physical activity
• Sedentary lifestyle: Not meeting recommended physical activity guidelines
• Poor diet: High intake of processed, high-fat and high-sugar foods
• Genetic factors: Some people are genetically predisposed to gain weight
• Medical conditions: Some health conditions and medications cause weight gain
• Psychological factors: Stress, depression and emotional eating

🏃 How Obesity Affects Sporting Performance

Obesity significantly impairs physical performance across multiple fitness components:

Reduced Cardiovascular Endurance

• Excess body weight increases the workload on the heart and lungs
• The heart must pump harder to deliver oxygen to a larger body mass
• VO₂ max is lower relative to body weight
• Fatigue occurs more quickly during aerobic activities
• Running, swimming and cycling are significantly harder

Reduced Flexibility

• Excess body fat limits the range of motion at joints
• Movement is restricted around the hips, knees and shoulders
• Difficult to perform techniques requiring full extension or rotation
• Gymnastics, diving and martial arts are particularly affected

Reduced Speed

• Carrying excess weight slows down sprint speed and acceleration
• Greater body mass requires more force to move quickly
• Change of direction is slower due to increased inertia
• Agility and reaction time may also be impaired

Increased Injury Risk

• Extra weight places greater stress on joints, especially knees and ankles
• Higher risk of stress fractures, osteoarthritis and ligament damage
• Falls and impacts cause more damage to a heavier body
• Recovery from injury is slower due to reduced fitness and circulation
• Back problems are common due to the strain of carrying excess weight

💔 Physical, Mental and Social Impacts of Obesity

Physical Impacts

• Increased risk of CHD, stroke, type 2 diabetes and certain cancers
• Joint problems (osteoarthritis) from carrying excess weight
• Breathing difficulties (sleep apnoea, asthma symptoms)
• High blood pressure and cholesterol
• Reduced mobility and ability to perform everyday tasks
• Fatigue and low energy levels

Mental/Emotional Impacts

• Low self-esteem and poor body image
• Depression and anxiety (higher rates among obese individuals)
• Stress from social stigma and discrimination
• Feelings of shame, embarrassment and isolation
• Reduced confidence to participate in physical activities
• Emotional eating creating a vicious cycle

Social Impacts

• Bullying and social stigma, especially among young people
• Discrimination in education and employment
• Avoidance of social situations involving physical activity or revealing clothing
• Difficulty participating in active social events
• Increased healthcare costs affecting family finances
• Social isolation from avoiding situations due to embarrassment

❓ Practice Questions

✅ Answers

1. A sedentary lifestyle is a way of living that involves little or no physical activity, characterised by prolonged sitting or inactivity. Three health consequences: (1) Obesity - low energy expenditure means excess calories are stored as fat, leading to weight gain and BMI over 30. (2) Coronary heart disease - lack of exercise weakens the heart, contributes to high cholesterol and blood pressure, and allows fatty deposits to build up in coronary arteries. (3) Osteoporosis - without weight-bearing exercise, bones do not receive the mechanical stress needed to maintain density, becoming weak and brittle with increased fracture risk.
2. BMI = Body Weight (kg) ÷ Height (m)² = 85 ÷ (1.70)² = 85 ÷ 2.89 = 29.4. Classification: Overweight (BMI 25.0-29.9). This person is at the upper end of the overweight category, close to the obese threshold of 30.
3. Obesity reduces cardiovascular endurance because the heart must work harder to pump blood and deliver oxygen to a larger body mass. VO₂ max relative to body weight is lower, meaning the obese person cannot sustain aerobic activity for as long. The extra weight increases the energy cost of movement, causing faster fatigue. Obesity increases injury risk because excess body weight places greater stress on weight-bearing joints (knees, ankles, hips), increasing the risk of osteoarthritis and stress fractures. Falls cause more damage due to the greater impact force of a heavier body. Recovery from injury is slower because reduced fitness levels and poorer circulation slow the healing process.
4. Mental impacts on a young person: low self-esteem and poor body image from comparing themselves to peers; depression and anxiety from social stigma; stress and embarrassment about their weight; lack of confidence to participate in physical activities, creating a vicious cycle. Social impacts: bullying and teasing about their weight at school; avoidance of PE lessons and social activities involving physical activity or swimming; social isolation from not joining in with active peers; potential discrimination and exclusion from friendship groups centred around sport and active play.
5. A sedentary lifestyle leads to type 2 diabetes through: (1) Lack of physical activity reduces the body's sensitivity to insulin, meaning cells are less able to absorb glucose from the blood. (2) Inactivity contributes to weight gain and excess body fat, particularly visceral fat around the abdomen, which is strongly linked to insulin resistance. (3) Without the regular blood glucose-lowering effects of exercise, blood sugar levels remain elevated over time. (4) The combination of insulin resistance and consistently high blood glucose eventually leads to the development of type 2 diabetes.
6. Muscle atrophy occurs because muscles that are not used regularly decrease in size and strength - the principle of "use it or lose it." Without regular resistance or weight-bearing activity, muscle fibres shrink and the body loses muscle mass. This creates a vicious cycle because: weaker muscles make physical activity harder and more tiring, the person exercises less due to the difficulty, muscles atrophy further from even less use, metabolic rate drops (muscle burns more calories than fat), making weight gain easier, the person becomes more sedentary, and the cycle continues. Breaking this cycle requires gradually increasing activity to rebuild muscle strength.

🎯 Exam Tips

• Know the BMI formula and categories - you may be asked to calculate and classify
• Sedentary lifestyle consequences: obesity, CHD, hypertension, type 2 diabetes, osteoporosis, muscle atrophy
• Always explain HOW inactivity causes each consequence, not just that it does
• Obesity affects performance: CV endurance, flexibility, speed and injury risk
• Address physical, mental AND social impacts separately for full marks
• Remember the "vicious cycle" concept - inactivity leads to problems that cause more inactivity

⚠️ Common Errors

📝 Exam Technique

⚠️ Common Errors

✍️ Model Answer

📊 AO Deep Dive

📝 Exam Questions by Topic

• AQA Past Papers - Topic Questions -- AQA
• Edexcel Past Papers - Topic Questions -- Edexcel
• OCR Past Papers - Topic Questions -- OCR
• Eduqas Past Papers - Topic Questions -- Eduqas
• CCEA Past Papers - Topic Questions -- CCEA

🎬 Video Resources

• BBC Bitesize - GCSE PE
• PE with Mr G
• myPEexam.org