Week 2

Introduction to Biomedical Physiology and Kinesiology

• This course introduces biomedical physiology and kinesiology.
• The image shows a human figure with a skeleton overlaid.

Anthropometry and Body Composition

• The slides show data for waist circumference, visceral adipose tissue, and thigh subcutaneous adipose tissue for 60 and 80-year-old males.
• Learning outcomes involve explaining the assumptions and limitations of human body composition measurement, and correlations between body composition and health.
• Learning goals involve building knowledge of human body composition, connecting body composition to health and athletic performance, and developing empathy for obesity prevalence in society.
• Key learning outcomes include defining body composition models, anthropometry, essential and storage fat (males & females), and describing obesity's health effects.
• Assumptions and limitations of common human body composition measurements are to be described.
• The interrelated determinants of body size and the prevalence of obesity will be described.
• The keys to a healthy lifestyle and body composition will be discussed.

Body Composition - Structure and models

• The human body is composed of many elements, with oxygen the most plentiful.
• The main elements include oxygen, carbon, hydrogen, nitrogen, etc.
• A chemical model of body composition includes fat, protein, carbohydrate, mineral and water
• Tissue types include nervous, epithelial, muscle and connective tissue.
• The human body has three structural components - muscle, skeleton, and fat.
• Body components vary based on gender.
• The two-component model describes the amount of fat and fat-free mass in the body.
• Fat-free mass primarily includes bone, muscle, water, vital organs, and connective tissue.

Why Assess Body Composition

• Knowledge of bone mineral content in women and children is critical for preventing osteoporosis.
• Monitoring body composition changes with growth, maturation, and aging is important for diagnosing disease.
• Changes associated with aging in developed countries often include increased fat mass, decreased muscle mass, and decreased bone mass.
• Healthy body composition is for health and performance goals in various sports and improving weight management/strength training.
• Assessing body composition is important for assessing health (obesity, chronic diseases, and low levels of fat/muscle).
• Sarcopenia (very low muscle mass) is a potential risk factor from aging.
• Activity can maintain muscle mass and healthy body composition.

Common Techniques for Assessing Body Composition

• Direct methods involve chemical analysis of human cadavers
• Indirect methods are non-invasive techniques used on living people.
• Techniques include: Height-Weight Tables, Body Density/Volume Measurements, Weight-Height Indices, Waist Circumference, Skinfold Measurements,CSEP-PATH Body Composition Assessment, O-Scale System, Bioelectrical Impedance Analysis, and Other Procedures (e.g., DEXA, CT, MRI).

BMI and Body Composition

• Body Mass Index (BMI) is a measure of body obesity, calculated by dividing weight (kg) by height (meters) squared.
• BMI classification standards for adults (20-70 years old) are provided, along with corresponding health risks.
• BMI is not always an accurate predictor of body composition. This is especially true for individuals with high proportions of muscle versus fat, or those with differing ethnic backgrounds.
• There are some criticisms of using BMI: it does not consider body composition, data is often from specific populations, and determining frame size is problematic.

Waist Circumference

• Waist circumference is an inexpensive and effective measure of central obesity. It strongly correlates with abdominal imaging and is associated with cardiovascular disease (CVD) risk.
• Waist circumference and waist-to-hip ratio are often better predictors of obesity-related health risks than BMI.

Skinfold Measurements

• Skinfold measurements are used to assess body fat.
• A 20% or more body fat percentage for men, or 30% or more for women, may be considered obese.
• Two primary ways to use fat folds are comparing differences in individuals across time and to use the summed measurements as an indication of relative fatness.
• Skinfold measurements are site-and sample-specific.
• Issues with measurement techniques may contribute to errors.

CSEP-PATH Body Composition Assessment

• This procedure uses BMI to first determine if a person is overweight or obese and then uses waist circumference to determine if abdominal fat is present.

Other Assessment Procedures

• Dual Energy X-ray Absorptiometry (DEXA) uses low-dose X-rays to measure bone mineral density and body composition.
• Computerized Tomography (CT) provides detailed images but the radiation dose is high.
• Magnetic Resonance Imaging (MRI) produces detailed images without using radiation.

Obesity and Energy Intake

• Trends in obesity, obesity related diagnoses and caloric density have increased significantly over time.
• Several factors, such as societal changes and increased consumption patterns, have contributed significantly to the rising obesity rate across populations.
• There is a relationship between body mass index and mortality risk.
• Data from 1981 to 2009 indicates a decline in the fitness levels of Canadian populations.

Determinant of Body Composition

• Genetics play a significant role in body size and proportions.
• Overfeeding studies and genetic studies support a role for genetics in impacting weight gain, but not wholly responsible for obesity.
• Many genetic sites associated with appetite regulation influence obesity risk..

Interrelated Causes of Obesity

• Factors such as social psychology, individual psychology, physical activity environment, and physiology are all interrelated and contribute to obesity.
• Social psychology includes media, peer pressure, food advertising. Individual psychology factors include self-esteem and stress. Physical activity environment factors include occupation and availability of transportation. Related physiological factors include genetics, epigenetics, appetite control, and food consumption. Food production includes affordability, portion size, energy density and availability of convenience foods.
• NEAT (non-exercise activity thermogenesis) is the energy expended through non-planned activities including sitting, standing, walking, fidgeting etc.

Participation

• Participation rates for physical activity are low in many regions.
• Children now spend more time using devices than their parents spent at work.

Keys to Healthy Body Composition

• A person's best weight involves a lifestyle that supports health and well-being.
• Losing fat often requires maintaining a calorie deficit through reduced caloric intake and/or increased energy expenditure.
• It is essential to maintain a healthy lifestyle rather than a quick-fix approach.
• A well-planned diet rich in varied nutrients is ideal, alongside regular exercise and time outdoors, which often include self-care and sleep.