Module 9 : Exercise

Lecture 11 : Exercise

Exercise

After discussing eating, in logical sequence we discuss exercise , its connection with health and itsconnection with eating. The physiological, the cognitive and the psychological effects of exercise aredocumented. The effects of exercise on aging, contextual factors that play a role in exercising andencouraging physical activity are further discussed.

There are two forms of exercise aerobic and anaerobic.

Aerobic exercise: is exercise that increases oxygen utilization in the body’s metabolic process. It ismoderate in intensity and of longer duration. Aerobic capacity is measured by the VO2 max test whichchecks maximal oxygen consumption by the body during exercise. It is expressed in liters per minute. The normal range for a young male is 3.5ltrs/min and for a young female is 2ltrs/min

Anaerobic Exercise: is exercise that does not use oxygen, which causes anaerobic metabolism. It isexercise that develops speed, power and strength and builds muscle e.g. weight lifting.

The recommended exercise routine is aerobic exercise everyday for 20 minutes and anaerobic exercisetwice or thrice a week.

The documented benefits of aerobic exercise include

increased efficiency of cardio respiratory system (lungs and heart)improved circulation and reduced blood pressureincreased red blood cells – oxygen transportationimproved muscle strengthincreased soft tissue and joint flexibilityimproved glucose tolerance increased longevity

According to the US surgeon general’s report (DHHS, 1996 , as cited in Marks et al., 2008)it wasestimated that physical inactivity leads to 400,000 preventable deaths (17%) per year. Physicalinactivity also impacts on morbidity especially cardiovascular disease, hypertension and diabetes ofwhich there may be a premature onset due to physical inactivity.

Mental Health

Plante & Rodin (1990) review suggests that physical activity improves mood and well being and reducesanxiety, depression and stress in healthy populations.

The biological pathways that mediate this effect are:

increases in body temperature due to exercise result in short term tranquilizing effectsreduction in resting muscle activity potential after exercise helps release tensionenhances neurotransmission of noradrenalin, serotonin and dopamine leading to improved mood.releases endorphins (natural opiates) (enhanced feeling well being) (Plante & Rodin, 1990).

The psychological pathways that mediate this effect are:

Physical fitness provides people with a sense of mastery, control and self sufficiency

Triggers an altered and more relaxed state of consciousnessProvides distraction, or time out from unpleasant cognitions emotions and behaviorRepeated pairing of the physical symptoms of the sympathetic ns in the absence of distressresults in improved psychological functioning (Plante & Rodin, 1990).

Thus the effects of exercise are not limited only to the body but also affect psychological processeswhich in turn affect general mental health.

In a year long longitudinal study of adolescents who exercised by Brown & Siegel (1988) it was foundthat the negative impact of stressful life events on health declined as exercise levels increased. Thenegative effects of stress on ill health have been documented; that exercise can have a protective effectagainst stress has important implications for both physical and mental health.

Exercise and Cognition

Castelli et al (2007) in a study with 259 3-5th graders found an association between their performanceon field exercise routine and math and reading scores on standardized tests. The children with the bestperformance on the field exercises also had the best math and reading scores.Researchers have found that in animal models exercising rats indicated higher levels of Brain derivedneurotrophic factor (BDNF) than control rats (Farmer et al 2004).

IGF-1 (insulin like growth factor1) crosses the blood brain barrier into the brain and orders theproduction of several chemicals including BDNFBDNF is associated with neurogenesis (birth of new neurons) and exercise increases BDNF levels in thehippocampus -an area associated with memory and learning (Cotman & Berchtold 2002; Neeper at al1995).

According to Vaynman et al (2004) “A brain low on BDNF shuts itself off to new information”

Blood Volume to the brain increases as a result of exercise which increases blood flow in the brain.

Astrocytes increase with exercise. Astrocytes are glial cells in the central nervous system that play asupporting role and help in myelination and repair. Thus these functions are also maintained withexercise.

Exercise and Aging

In a study by Larson et al (2006)1,740 men and women above the age of 65 were asked about theirlevels of physical activity and related factors such as diet, lifestyle, health and smoking and drinkingwere taken into account. They were followed for 6.2 years - it was found that the incidence rate forAlzheimer’s dementia was significantly higher for those who exercised fewer than 3 times a week.

Alzheimer’s and vascular dementia may get postponed with regular exercise.

Cognitive function

Aging brains benefit from exercise and show the effects of BDNF – older adults who exercised faredbetter on cognitive tests.

Safdara, et al. (2011) in a study with rats who had malfunctioning mitochondria (which causespremature aging) were divided into 2 groups, one that exercised and one that didn’t otherwise theirenvironments were similar. The exercise group ran on a wheel for 45 min 3 times a week. which byhuman standards is like running 6.2 miles. This continued for 5 months. When they were compared thesedentary rats were bald, frail and dying the running rats were youthful with full pelts of dark fur and alltheir muscle mass and brain volume intact.

Who are these people who exercise regularly?

What are the factors that predict regular exercise? (Marks et al, 2000)

Gender – women are less active than men especially through adolescence and adulthood even if thelevels of activity were similar in childhood. In India especially among the middle class sometimeswomen have very low levels of physical activity.

SES – people from the lower SES have higher activity levels because of their jobs which may be manualhowever they are less likely to voluntarily exercise as compared to those from a higher SES. In theBritish Whitehall study it was found that 95% of men at the highest grade exercised as opposed to 69%at the lowest grade.

Education impacts on activity levels data from the Center for Disease control in the U.S (2008) indicatesthat almost half of those with less than a high school education do not exercise as opposed to only 15%of college graduates.

Family can have an impact on exercise behavior. There is a norm of exercise and time is made for itand members may engage in an activity together. Families where most of the members exercise, mayperceive themselves as athletic and feel responsible for their health.

Self efficacy beliefs – refers to the individual’s confidence or sense of mastery or control over aparticular behavior (Bandura’s Social Learning Theory, 1986). Self efficacy has been found to be relatedto higher levels of exercising. Research has looked at barrier self efficacy (self efficacy to overcomebarriers to regular exercise) and scheduling self –efficacy.

Characteristics of the Setting

How does location or the physical situation affect exercise?

The physical surroundings include weather (extreme temperatures are unpleasant to exercise in). In theU.S. there are heated gyms and in India there are air conditioned gyms for those who can afford it. Thatbrings us to the issue of cost, what are the costs incurred to exercise – do you have to travel a longway to get to a open space, how expensive are gyms, are there other activities that can be engaged ineasily?

Walkability of neighborhoods - Mixed land use results in a mix of destinations to walk to (walk to thegrocery etc). Street connectivity and neighborhood aesthetics also encourage walking. Safety concernsare another important factor that influence how much people walk and use open spaces. Exercise facilities or open spaces in the neighborhood are another vital factor in determining levels ofactivity.

In a study by Zenk et al (2009) on characteristics of the Neighborhood Environment and Adherence to aWalking Intervention in African American Women most of the above factors were considered. Resultsrevealed that the availability of indoor walking spaces in their neighborhood predicted adherence to theintervention program. Thus women may feel safer in an indoor facility and it gives them the flexibility oftime to exercise at a later time in the evening when they are free from household reponsibilities .

Social and Cultural Norms

In certain societies there is a norm to exercise or be physically fit such as the U.S. or the Scandinaviancountries or Germany whereas in other developing societies this norm may not be there as neitherleisure time nor facilities are available and it is not important as opposed to earning a living. In the

developing countries the elite would follow western norms in keeping with their lifestyle. Urbanmiddleclass women would be more likely to exercise than their counterparts in small towns or ruralareas

Encouraging Physical Activity

Given the value of physical activity in reducing and postponing morbidity, one can see it’s largerimplications for productivity, for lowered costs in healthcare and optimal functioning.Thus there is an effort to increase levels of physical activity at the population level in developedcountries. Programs that have been effective were home based and encouraged walking and hadfrequent professional contact (Marks et al, 2000).

Effort needs to be directed to creating a habit of regular exercise among the young as well as high riskpopulations.

Those forms of exercise that are indigenous to the culture are more likely to succeed such as yoga orkabbadi or cricket in India. That yoga has become an international craze but is not as widely practiced inIndia is telling.

Exercise that is fun and has some socializing involved is more likely to be effective in terms of peoplebeing regular about it (walking with friends or playing badminton with them).Home based, informal,moderate intensity, walking for e.g – would be most likely to succeed.

Interventions need to focus on how to prevent relapse as most people tend to relapse after a while.Some of the strategies suggested by Robinson & Rogers (1994) is providing cues that remind people ofthe program, combining behavioral and cognitive strategies, providing rewards and punishments andincreasing people’s belief that they have control over the design and conduct of the program. References

Bandura, A. (1986). Social Foundations of Thought and Action: A Social Cognitive Theory.Englewood Cliffs, NJ.: Prentice-Hall.Brown, J. D. & Siegal, J. M. (1988). Exercise as a buffer of life stress: A prospective study ofadolescent health. Health Psychology, 7 (4), 341-353.Castelli, D, M., Hillman, C.H., Buck, S.M.& Erwin, H.M., (2007).Physical Fitness andacademic achievement in Third- and Fifth-Grade Students. Journal of Sport & ExercisePsychology, 29, pp. 239-252.Cotman, C. W. & Berchtold, N.C. (2002). Exercise: a behavioral intervention to enhance brainhealth and plasticity. Trends in Neuroscience, 25 (6), 295-301.Farmer, J., Zhao, X., van Praag, H., Wodtke, K., Gage, F. H., & Christie, B. R. (2004). Effects ofvoluntary exercise on synaptic plasticity and gene expression in the dentate gyrus of adult maleSprague-Dawley rats in vivo. Neuroscience, 124 (1), 71-79.Larson, E. B., Wang, L., Bown, J. D., McCormick, W. C., Teri, L., Crane, P. & Kukull, W. (2006).Exercise is associated with reduced risk for incident dementia among persons 65 years of age andolder. Annals of Internal Medicine, 144 (2), 73-81.Marks, D.F., Murray, M., Evans, B., Willig, C., Woodall, C., & Sykes, C. (2008). Exercise andactivity. In Health Psychology (2nd ed) (pp. 194-214). New Delhi: Sage.Neeper, S. A., Goauctemez-Pinilla, F., Choi, J. & Cotman, C. (1995). Exercise and brainneurotrophins. Nature, 373 (109). doi:10.1038/373109a0.Plante, T.G. & Rodin, J. (1990). Physical fitness and enhanced psychological health. CurrentPsychology: Research & Reviews, 9 (1), 3-24.Robinson, J. I. & Rogers, M. A. (1994). Adherence to exercise programmes: Recommendations.Sports Medicine, 17 (1), 39-52.Safdara, A., Bourgeoisd, J. M., Ogborne, D. I., Littlea, J. P., Hettingab, B. P., Akhtarb, M. et al.,(2011). Endurance exercise rescues progeroid aging and induces systemic mitochondrialrejuvenation in mtDNA mutator mice. Proceedings of the National Academy of Sciences of theUnited State of America. doi:10.1073/pnas.1019581108.U.S. Department of Health and Human Services. 2008 Physical Activity Guidelines for Americans.Washington, DC: U.S. Department of Health and Human Services; 2008.Vaynman, S., Ying, Z., & Gomez-Pinilla, F. (2004). Hippocampal BDNF mediates the efficacy ofexercise on synaptic plasticity and cognition. The European Journal of Neuroscience, 20 (10),2580-2590.Zenk, S. N., Wilbur, J., Wang, E., McDevitt, J., Oh, A., Block, R., McNeil, S. & Savar, N. (2009).

Neighborhood environment and adherence to a walking intervention in African-American women.Health Education & Behavior, 36 (1), 167-181. doi: 10.1177/1090198108321249