A.3.2 Benefits to Health of Being Active

Adapted from class notes.

Benefits to an Active Lifestyle

• Prevents diseases such as diabetes, heart disease, stroke, some cancer

• Reduces risk of obesity

• Improves mental health, symptoms of depression and anxiety

• Improves cognitive ability

• Improves sleep

• Improves balance

• Improves bone health

Immunity

• Pathogens are disease causing microbes

• Around 45 minutes of exercise regularly will support the immune system

• Evolutionarily, short term stress increases preparation for danger/disease (increases immune function)

• Norepinephrine, epinephrine, and cortisol signal leukocytes (WBCs) movement to the skin, intestines, lung, liver, lymph (places where pathogens might first enter the body)

• Increased risk factors include intense training (and in the cold), travel, low energy, poor nutrition, psychological stress, lack of sleep, environmental extremes

• Upper respiratory infections are common in athletes. Proper nutrition, sleep, and training loads are necessary

Models for Activity and Immunity

• A j-curve graph shows the risk of upper respiratory tract infections with activity. Lowest at regular training, highest with overtraining, and inactivity is between them.

  • Example: 60 miles/week vs. 20 miles/week were twice as likely to have URTI

• When elite athletes are considered, the J becomes an S curve

• If inadequate recovery after periods of overreaching, the athlete is more susceptible to infection. “Open window” model

Recommendations for Healthy Immune Function

• Effective management of training load

• Have an easy workout following a difficult workout

• Easy weeks every 2-3 weeks

• Manage physical and psychological stress

• Manage life demands

• Mood, stress, anxiety

• 7 hours of sleep per night

• Sleep hygiene

  • Dark sleep

  • Be mindful of heat and altitude

• Short exposure to extreme environments

• Eat enough

• Balance of nutrition

Risks of Inactivity

• Similar professions show that an inactive lifestyle are twice as likely to suffer heart disease (bus drivers vs bus conductors)

• Hypokinetic disease - Associated with an inactive lifestyle

  • Cardiovascular disease, cancers, obesity, type 2 diabetes, osteoporosis, mental health disorders

  • More than one factor contributes to each of these beyond inactivity

• Prevalence = people with disease/people in population

• Incidence = estimation of new cases

Metabolic Equivalent of Task (MET)

• 1 MET is the oxygen consumption or energy expenditure at rest per unit of body mass

  • 3.5mL O2 x kg-1 x min-1 or 1kcal x kg-1 x hr-1

  • A 100kg man running at 10 MET is consuming 3500mLO2 x min-1 or buring 1000kcal x hr-1

• Higher MET is more vigorous exercise. 4-6 is moderate, >6 is vigorous

Cardiovascular Disease

• Hypertension, coronary heart disease, stroke

• Coronary heart disease was responsible for nearly 9 million deaths in 2019 (leading cause)

  • Stroke number 2 at over 6 million

• Atherosclerosis - Hardening of arteries due to fat and cholesterol. These can cause a full blockage or break off and block somewhere else

• Physical activity reduces modifiable risks through:

  • Increasing coronary artery size

  • Ability to vasodilate

  • Lowering incidence of obesity, diabetes, hypertension, cholesterol

  • High levels of HDL-cholesterol

Obesity

• Excess body fat can potentially endanger health

• BMI (body mass index) relates height to weight

  • Misleading because it doesn’t account for body composition, only mass. Meaning someonw with a large muscle mass would rank as overweight or even obese

• For people who do not have excessive muscle mass, fairly useful

• Too high (25 or over), or too low (under 18.5) shows an increased risk of CVD

• Obesity prevalence is increasing worldwide, which is also increasing prevalence of other hypokinetic diseases

Energy Balance

• Weight is largely determined by calories in/calories out

  • When intake is more than use, then weight gain

  • When use is more than intake, then weight loss

  • When use and intale are equal, then weight maintenance

• More factors will influence weight such as:

  • Taking in fewer calories will eventually lead to lower metabolic rate

• Ghrelin is a hormone that sitmulate hunger; Leptin is a hormone that suppresses hunger

  • Availability, desirability, and affordability also affect appetite

• Physical activity increases the energy use part of the equation

• ACSM recommmends 150-250 minutes of exercise/week is recommended for preventing obesity (others higher)

• Individual differences (both genetically and environmentally) will affect speed of weight loss

Type 1 Diabetes and Type 2 Diabetes

• Diabetes is characterized by high blood sugar (hyperglycaemia, >10mmol/L; normal ~5mmol/L)

• Type 1 Diabetes is an autoimmune disease that is potentially hereditable in which immune cells destroy insulin producing cells of the pancreas

• Type 2 Diabetes is a lifestyle disease (with genetic influence) mainly caused by insulin resistance due to low activity and consistent high blood sugar. Insulin resistance means that insulin is there, but cells don’t respond to it

  • Major risk factors - Obesity related to overeating/inactivity; certain ethnicities

• Diabetes can cause risk to health such as:

  • Stroke

  • Retinopathy (damage to the light receptor cells)

  • Coronary heart disease

  • Nephropathy (kidney damage)

  • Peripheral vascular disease (narrowing of blood vessels)

  • Neuropathy (nerve damage)

  • Diabetic foot

• Exercise increases insulin sensitivity, when cells respond more to insulin (insulin has a greater effect of lowering blood sugar)

Bones

• Bones are a compromise of strength and lightness. Heavy bones would be too difficult to move

• Bone mineral density (BMD) is the main determinant of bone strength. Peaks between 25-45 years

• Bone density is lower in females, decreases (faster than in males) following menopause (low estrogen)

• Low calcium intake causes calcium stores in the bones to be depleted, decreasing BMD and leading to osteoporosis

• Osteoporosis is a severe loss of bone mass, making bone fractures more easy

• Bones are naturally a lattice. Between osteoporosis and normal is osteopenia

• Weight bearing exercise decreases demineralization