Assignment 2

1. What was the unique way Dr. Morris combined the areas of physical activity and public health?

Dr. Morris conducted a study on workers (large group of men who worked all day moving people around the city of London) employed by the London transport system. Dr. Morris assessed their physical activity rates and then related it to the risk of getting a heart attack. Dr. Morris studied the bus drivers who were inactive all day long and the conductors who were walking up and down the stairs of the buses taking tickets from riders all day. (Morris et al. 1953) Physically active conductors had significantly lower rates of coronary heart disease than the drivers. If conductors did develop the disease, it was less severe and occurred at later ages. Dr. Morris promoted physical activity and health, not just exercise for performance.

Dr. Morris also found that postmen delivering the mail on foot had similarly lower CHD rates than sedentary postal clerks and telephonists. Analysing national death rates in an early test of their hypothesis, the Morris team found gradient levels of CHD with occupations of intermediate physical activity.

Dr. Morris chose middle aged civil servants free of clinical CHD who held sedentary desk jobs and traced them over time for CHD occurrence and death. Contrary to expectation, no benefit in lower heart attack incidence was found from high totals of leisure time physical activity. Instead, men engaging in vigorous exercise (for example, running at about 6 mph) did manifest less than half the disease of their fellow workers, who were comparable in health status and health habits. (Paffenbarger, R. S., 2000)

2. What is the exercise/heart hypothesis?

Exercise/ heart hypothesis protects against coronary heart disease. People who exercised more frequently had healthier, better functioning circulatory systems than those who did not exercise. This physiological benefit resulted in a lower risk of death from heart disease among those who were more active. Nowaday, in primary prevention, regular physical activity decreases the incidence of cardiovascular disease. Exercise has an effect on cardiovascular improvement in lean and overweight normoglycemic subjects. In a 1-year study in non-obese individuals, without dietary intervention, a 16-20% increase in energy expenditure (any form of exercise) resulted in a 22.3% reduction in body fat mass, LDL cholesterol , total cholesterol/high-density lipoprotein lowering ratio, and C-reactive protein concentration, all risk factors associated with CVD.(Fontana L, 2007)

Exercise induces adaptations in several cell types and tissues throughout the body. Exercise increases mitochondrial biosynthesis in adipocytes, skeletal muscle myocytes, and cardiomyocytes, thereby increasing aerobic respiration within these tissues. In addition, exercise improves systemic oxygen delivery through vasodilation and angiogenesis, preventing cardiac ischemia-reperfusion injury. In addition, exercise leads to long-term anti-inflammatory effects that are inversely associated with increased inflammation commonly seen in CVD and obesity. (Kasapis C, 2005)

3. What are five chronic disease conditions that might be positively influenced by participation in regular physical activity? Discuss each.

Heart disease: Dr. Morris found that the physically active conductors had significantly lower rates of coronary heart disease than the less active drivers. The exercise/heart hypothesis, now more of an accepted fact than a hypothesis. People who exercised more frequently had healthier, better functioning circulatory systems than similar people who did not exercise. Regular physical activity also results in lower blood pressure, healthier cholesterol levels, and better blood sugar regulation. It encourages the heart’s arteries to dilate more readily.

Cancer: Physical activity, including both aerobic and resistance exercise, has protective effects on cancer risk because it improves insulin sensitivity, reduces circulating insulin levels, increases glucose intake by skeletal muscle, lowers fatty acid synthesis, and improves immunity.

Stroke: Physical activity provides strong preventative effects on stroke recurrence. The American Stroke Association (ASA) noted that physical activity reduces blood pressure, improves endothelial function, reduces insulin resistance, improves lipid metabolism, and may help reduce weight. Physical activity helps lower high blood pressure which is an important risk factor for stroke. It can control other things that can put at risk such as obesity, and high cholesterol.

Pulmonary disease: Physical activity especially aerobic exercise can improve the circulation and help the body better use oxygen. Build energy levels so that people can do more activities without becoming tired or short of breath.

Osteoporosis: Physical activity can reduce bone loss in terms of reducing fracture risk. When people exercise regularly, the bone adapts by building more bone and becoming denser. It also improves balance and coordination.

Diabetes mellitus: Physical activity can make the body more sensitive to insulin which helps manage diabetes. It can also help control blood sugar levels. It can also helps control weight.

4. What are the 2018 Physical Activity Guidelines for Americans?

For children (aged 3 to 5 years), preschool-aged children should be active throughout the day to enhance growth and development. Children this age should be encouraged into active play for at least 3 hours per day. For children and adolescents (aged 6 to 17 years), children and adolescents should do 1 hour or more of physical activity every day. Most of the 1 hour or more per day should be either moderate or vigorous intensity aerobic physical activity. As part of their daily physical activity children and adolescents should do vigorous-intensity activity at least 3 days per week. They also should do muscle-strengthening and bone-strengthening activity at least 3 days per week. For adults (aged 18 to 64), adults should do 2 hours and 30 minutes per week of moderate-intensity, or 1 hour and 15 minutes per week of vigorous-intensity aerobic physical activity, or an equivalent combination of moderate and vigorous intensity aerobic physical activity. Aerobic activity should be performed in episodes of at least 10 minutes, preferably spread throughout the week. Additional health benefits are provided by increasing to 5 hours per week of moderate-intensity aerobic physical activity, or 2 hours and 30 minutes per week of vigorous-intensity physical activity, or an equivalent combination of both. Adults should also do muscle-strengthening activities that involve all major muscle groups performed on two or more days per week. For older adults (aged 65 and older), they should follow the adult guidelines. If this is not possible due to limiting chronic conditions, older adults should be as physically active as their abilities allow. It is important for older adults to avoid inactivity. Older adults should do exercises that maintain or improve balance if they are at risk of falling.

5. Define the following terms:

(a) total energy expenditure - TEE, also referred to as total caloric expenditure - The combination of one’s resting metabolism (basal metabolic energy expenditure), thermic effect of food, and physical activity energy expenditure over time, usually expressed as kilocalories.

(b) thermic effect of food - TEF, the amount of energy that is used to digest and metabolize energy that is ingested (food and drink). Usually expressed as kilocalories.

(c) basal metabolic energy expenditure - BMEE, the energy expended to maintain breathing and circulation while at rest; usually expressed as kilocalories.

(d) accelerometers - Small piezoelectric devices that estimate physical activity energy expenditure by measuring movement. Specifically, they measure the magnitude and direction of acceleration. They constitute an indirect measure of physical activity.

(e) pedometers - electronic monitoring devices that can be used to take the recall bias out of physical activity assessment. They are usually most useful for measuring walking, running or jogging, or any other type of physical activity that involves the lower body. Some rely on a spring or a spring lever to record the movement, others use a strain gauge, and still others use a magnetic switch.

6. What two direct observation techniques are commonly used for measurement of physical Activity?

Sofit is a system for observing fitness instruction time and Soparc is a system for observing play and recreation in communities. They are two examples of direct observation techniques to assess physical activity among children and adolescents in defined areas. Both measure, developed at San Diego State University by Dr. Thom Mckenzie and colleagues have helped to get objective measures of physical activity in youth. SOFIT is used to assess the amount of physical activity occurring during physical education classes, or during any physical activity class setting (e.g. an aerobics or yoga class). SOFIT provides important information about the quality of the physical activity class by measuring not only the amount of physical activity the students are engaging in during class, but also the quality of specific class activity and behaviors of the instructor. SOPARC is used to measure physical activity and associated environmental characteristics in park and recreational settings.

If an organization may be interested in diagnosing and improving the levels of physical activity occurring in public recreation centers in low-income neighborhoods. SOPARC would be an excellent tool for measuring physical activity in that project. Therefore, direct observation techniques can be very useful in many situations.

7. What is public health surveillance, and how does it apply to physical activity measures? what are the three sources of public health surveillance data related to physical activity behaviors?

Public health surveillance is the continuous, systematic collection, analysis and interpretation of health-related data (e.g. regarding agent or hazard, risk factor, exposure, or health event) needed for the planning, implementation, and evaluation of public health practice. Surveillance helps understand the extent of a health problem and identify the types of people and populations that may be at higher risk of that health problem. Physical activity is any skeletal movement that results in energy expenditure. It is a behavior and energy expenditure in the direct result that physical activity has on bodies. The most accurate techniques to measure physical activity are those that involve quantifying the amount of energy expenditure that results from being physically active. It is because noncommunicable diseases are becoming an issue, acknowledging physical activity and its importance in decreasing disease risk helps determine the dose

and types of physical activity needed for health benefits. For example, the best science-based guidelines state that adults should accumulate at least 150 minutes per week of moderate-intensity physical activity or at least 75 minutes per week of vigorous-intensity physical activity or some equivalent combination of intensities (U.S. Department of Health and Human Services, 2018) People who do moderate and vigorous PA# of people who meet the physical activity guidelines; prevalence of physical activities and sedentary behavior.

Surveillance of physical activity is a core public health function that is necessary for monitoring population engagement in physical activity, including participation in physical activity initiatives. Surveillance activities are guided by standard protocols and are used to establish baseline data and to track implementation and evaluation of interventions, programs, and policies that aim to increase physical activity.

The three sources of public health surveillance data related to physical behaviors are The International Physical Activity Questionnaire (IPAQ), Global Physical Activity Questionnaire (GPAQ), National Health Interview Survey. Questions like what proportion of adults in a population are active at recommended levels? How many report regular walking? Do these proportions vary by age, sex, or race or ethnicity? What are long-term trends in these values over time? Etc.

References:

1. Paffenbarger, R. S. (2000, June 1). Jerry Morris: Pathfinder for health through an active and fit way of life. British Journal of Sports Medicine. Retrieved March 14, 2022, from https://bjsm.bmj.com/content/34/3/217

2. Kohl, H. W., Murray, T. D., & Salvo, D. (2020). Foundations of Physical Activity and Public Health. Human Kinetics.

3. Fontana L, Villareal DT, Weiss EP, Racette SB, Steger-May K, Klein S, et al. C.G. Washington University School of Medicine, Calorie restriction or exercise: effects on coronary heart disease risk factors. A randomized, controlled trial. Am J Physiol Endocrinol Metab. (2007) 293:E197–202. doi: 10.1152/ajpendo.00102.2007

4. Kasapis C, Thompson PD. The effects of physical activity on serum C-reactive protein and inflammatory markers - A systematic review. J Am Coll Cardiol. (2005) 45:1563–9. doi: 10.1016/j.jacc.2004.12.077