Transcript EXERCISE PHYSIOLOGY - University of Jaffna

Prof K. Sivapalan
Department of Physiology,
Faculty of Medicine,
University of Jaffna
• Physical exercise is any bodily activity that
enhances or maintains physical fitness and overall
health and wellness.
• It is performed for various reasons including
strengthening muscles and the cardiovascular
system, honing athletic skills, weight loss or
maintenance, as well as for the purpose of
enjoyment.
• Day to day activities involving musculo-skeletal
system also gives the same effect as exercise but
it depends on the intensity and extent of the work
involved.
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• The strength of a muscle is determined
mainly by its size
• Maximal contractile force is between 3 and 4
kg/cm2 of muscle cross-sectional area
[number of myofibrils].
• Cross sectional area of the quadriceps of
world class weight lifter- 150 cm2 – 525 kg.
• The holding strength of muscles is about 40
per cent greater than the contractile strength.
• This would increase the strength to 735 kg.
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• Power is determined by strength, distance
of contraction and number of times per
minute.
• Power is the work done in a unit timeexpressed as kg-m/min.
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• The maximal power [kg-m/min] achievable by all
the muscles in a highly trained athlete:
– First 8 to 10 seconds
– Next 1 minute
– Next 30 minutes
7000
4000
1700
• The power output of the muscles is only one fourth
as great as during the initial power surge.
• Efficiency of translation of power to performance is
low at rapid activity than sustained activity: velocity
of 100 M dash is only 1.75 times more than 30
minute race.
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• Ability to remain active for a long period.
• Related to the nutritive support for the
muscle
EnduranceMin.
Glycogeng/kg
High carbohydrate
240
40
Mixed
120
20
High fat
85
6
Diet
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• The amount of ATP present in the muscles, even
in a well-trained athlete, is sufficient to sustain
maximal muscle power for only about 3 seconds
• The combined amounts of cell ATP and cell
phosphocreatine can provide maximal muscle
power for 8 to 10 seconds
• Glycogen-lactic acid system can provide 1.3 to 1.6
minutes of maximal muscle activity.
• This system can form ATP molecules about 2.5
times as rapidly as can the oxidative mechanism
of the mitochondria.
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• Muscles that contract at more than 50 %
of the maximal force develop strength
rapidly even if done few contractions per
day.
• Contractions with less force, without
resistance, will not develop strength
irrespective of the extent.
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• Hypertrophy – increased myofibrils.
• Increase in mitochondrial enzymes [120%]
• Phosphagen metabolic system [60-80%]
• Stored glycogen [50%]
• Stored triglyceride [75-100%]
• Rate and efficiency of oxidative metabolic
system [45%]
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Fast-twitch
Slow-twitch
Large in diameter [2 times]
Less in diameter
Phosphagen and glycogenlactic acid enzyme more
active [2-3 times]
More mitochondria,
myoglobin and enzymes for
aerobic metabolism
Less capillaries
More capillaries
Deliver extreme amounts of
power for short periods.
Provide endurance
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• Proportion of fast or slow twitch fibers appears to be
genetically determined.
• Change of the muscle type on training is minimal.
• Percentages of fibers in quadriceps muscle:
Fast
Slow
Marathoners
18
82
Swimmers
26
74
Average male
55
45
Weight lifters
55
45
Sprinters
63
37
Jumpers
63
37
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• Oxygen consumption [ml/min] under maximal
conditions:
– Untrained average male
– Athletically trained male
– Male marathon runner
3600
4000
5100
• Relation between oxygen consumption and
pulmonary ventilation is linear.
• Limits of pulmonary ventilation L/min:
– Maximal exercise ventilation– Maximal breathing capacity
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100-110
150-170
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• Training increases oxygen maximal
consumption in about 8 weeks by 10%
• Oxygen diffusing capacity appears to be
genetically determined:
– Nonathlete at rest [ml/min]
23
– Nonathlete on maximal exercise
48
– Speed skaters on maximal exercise
64
– Swimmers on maximal exercise
71
– Oarsman on maximal exercise
80
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• The increase during exercise is due to increased
pulmonary blood flow.
• Blood flow through many capillaries at rest is sluggish
but increased blood flow provides larger surface for
diffusion.
• Genetic predisposition for diffusing capacity?
• Not much change in arterial blood gas concentration in
exercise.
• Stimuli for Increased Respiration:
– Motor out flow on respiratory center.
– Proprioception from muscles and joints
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• Nicotine causes constriction of the terminal bronchioles of the
lungs, which increases the resistance of airflow.
• Irritating effects of the smoke increases fluid secretion into the
bronchial tree and swelling of the epithelial linings.
• Nicotine paralyzes the cilia of the respiratory epithelial cells
and debris accumulates in the passageways and adds to the
difficulty of breathing.
• Chronic smoking– Emphysema
– Chronic bronchitis
– Obstruction of terminal bronchiols
– Destruction of alveolar walls
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• Resting blood flow to resting muscle- 3.6
ml/100 g muscle/min
• During maximal exercise- 90 ml/100g/min
• Cardiac Output:
– Young man at rest-
5.5
– Young man at maximal exercise
23
– Marathoner at maximal exercise
30
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• In marathoners,
– Volume of chambers increase by 40 %
– Heart mass increase by 40 %
Stroke Heart Rate
Volume (beats/min)
(ml)
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Resting nonathlete
75
75
Resting marathoner
105
50
Maximum- nonathlete
110
195
Maximum-marathoner
162
185
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• Heat production increases with exercise which can
in crease body temperature to dangerous level
due to inability to eliminate the heat in hot and
humid environment or heavy clothing.
• Heat stroke: when body temperature goes to 4142 °C, it is destructive to tissue cells [including
brain] – symptoms are,
– Extreme weakness, exhaustion, headache, dizziness,
nausea, profuse sweating, confusion, staggering gait,
collapse, and unconsciousness
• It is fatal because temperature regulation is lost
and many enzymes have doubled their activities.
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• Fluid loss:
– Sweating
– Tissue fluids in muscles
• Effect on reduction of body weight by:
– 3%: diminished performance
– 5-10%: muscle cramps, nausea etc.
• By hypovoluaemia, haemoconcentration,
hyponatreamia, hypokalaemia [aldosterone]
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• Increases performance by staircase
phenomenon
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• Starling law of relationship to initial length
to the force generated.
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• High carbohydrate diet vs high fat diet
• ? Protein intake
• Vitamins and minerals
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• Facilitate heat loss
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• Quality- same
• Quantity- more in males due to testesteron
• Endurance- females have advantage
because of high energy store
• Problems of menstruation, pregnancy
• ? Efficiency due to pelvic and other
skeletal structural differences.
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Prof K. Sivapalan
Department of Physiology,
Faculty of Medicine,
University of Jaffna
• Evolution: hunter-gatherer
• Body Composition: Muscles (40%)and Bones
• Motor Centers in Brain: Cerebellum and Basal ganglia,
Motor Cortex, Brain Stem and Spinal Cord
• Control of physical activity: Neocortex [on the basis of
short and long term health, physical and other
benefits] vs Limbic System [on the basis of emotion]
• Technology: Automation and communication →
comfort → unhealthy life style
• Tissues: “USE IT OR LOSE IT”
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• Energy intake = exercise energy expenditure + energy
needed for all other functions ± body energy content
• Inadequate energy intake: ↓ muscle mass; ↓bone density;
↑risk of fatigue, injury, and illness and reproductive
dysfunction.
• Eating: before or after exercise- before for glycaemic control.
• Vitamins and minerals: Vitamins B, C, D, E and beta carotene
and minerals like calcium, iron, zinc, magnesium and
selenium – ?weight reduction and diet restriction.
• Fluid & electrolytes: dehydration and hyponatremia (muscle
cramps)
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• Enzymes for oxidation of Fat- ↑,
Carbohydrate- ↓
• ↑ oxidative capacity, ↓ glycogen depletion
• ↑ insulin sensitivity and ↓ leptin level
• When Energy Intake >Energy Expenditure,
↑ serum cholesterol and phospholipids.
• Sprint- ↑post-exercise metabolism –weight
reduction.
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• Regular exercise reduces the risk of type 2 diabetes in
overweight/obese individuals.
• Regular walking exercise: increased energy consumption, and
decreased FBG, HbA1c, and TG levels. Better response if
done after dinner.
• Incidence of complications of type II diabetes might be
reduced by implementing a regular walking exercise program.
• Moderate exercise: muscular uptake of glucose exceeds
hepatic glucose production, and blood glucose decline during
the activity.
• Plasma insulin levels concomitantly fall, making the risk of
exercise-induced hypoglycemia low as long as the individual
is not injecting insulin or taking insulin secretagogues.
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• Hypertrophy
• Feed arteries in rats: young- increase in
number of vessels, old- increased cross
sectional area of the vessels
• Gene expression: heat shock proteinsmaintain homeostasis, facilitate repair from
injury and preserve muscle function in aging.
• Anabolic effect of nutrient intake- prevent
sarcopenia in old age.
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•
Articular cartilage volume: proportional to physical activity – exercise in
older women did not show increase.
•
Postmortom findings in Horse: increase in hyaline cartilage, calcified
cartilage and subchondral bone thickness- ? Growing children.
•
Joint form: during postnatal ontogeny, it is modified primarily through
differential rates of articular cartilage proliferation across articular surfaces.
? Regulated by the magnitude and orientation of stresses in the articular
cartilage.
•
Epiphysial growth is stimulated by weight bearing.
•
Bone mass and architecture: Load-bearing is an important functional
influence. Bone's adaptive response to load-bearing depends on functional
strains. Remodeling – along the line of stress.
•
Fibroblast growth factor 21: research on blood glucose. ? Action on tissuescontribution in making tendons and ligaments stronger.
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• Excessive weight bearing on epiphysis - damage and
stunting.
• Injuries to muscles and bones occur by over use,
accidents and foul play in games.
• More physically active individuals had more knee
abnormalities.
• ? Running and osteoarthritis- may depend on preexisting health of the joint.
• Stress of competitive sports overweigh the benefits of
exercise by the action of stress hormones.
• Effects of exercise in illnesses like viral infections, liver
diseases and kidney diseases need consideration.
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• Antibody production: optimal in moderate exercise, suppression in
intense exercise.
• This transient suppression returns to normal in 24 hours. ? Can
become a chronic depression of acquired immunityif intense
exercise continues- may be due to elevated circulating stress
hormones, alterations in the pro/anti-inflammatory cytokine balance
• Exercise alters the number and function of neutrophils, monocytes
and natural killer cells- ?anti inflammatory effect of exercise.
• Prophylactic effect on insulin resistance, atherosclerosis, tumour
growth and neurodegeneration. ? Antiinflammatory effect
• Enhanced anti-tumour immunity: ?protection against
postmenopausal breast cancer and cancers of colon, endometrium,
lung and pancreas.
• AIDS: Moderate physical activity may slow HIV disease progression.
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• Improved pulmonary function at rest and exercise
[greator operating lung volumes]
• ?increased incidence of respiratory infection?immuno-suppression by exercise.
? Cool air and dust load of hyperventilation.
? Body temperature fluctuations- exercise and bathing.
• Exercise induced asthma- ?triggered by cool air
• Significant benefits from exercise training in Acute
Exacerbation of Chronic Obstructive Pulmonary Disease,
COPD, and conditions that are common co-morbidities
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• Thrombotic risk increases with aging-↑fibrinogen, factor VII, PAI-1
and plasma viscosity. Regular physical exercise ↓ risk
• Acute exercise [unaccustomed strenuous physical exertion]:
transient activation of the coagulation system, accompanied by an
increase in the fibrinolytic capacity.
• Acute exertion may precipitate ischeamic cardiac problems due to:
– Increased coagulability
– ?reduced plasma volume and haemo-concentration
– Rupture of a small, inflamed, coronary plaque and the activation
of thrombogenic factors
• Long-term moderate or strenuous physical activity is associated with
a considerable reduction in cardiovascular morbidity and mortality.
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• Resting heart rate, heart rate recovery, exercise HR, and exercise
blood pressure: strong association in runners and swimmers, less in
walkers and least in sedentary.
• Larger end diastolic volume and wall thickness, more in males [not
exceeded the limit of resolution].
• Transport capacity: ↑blood flow and capillary exchange.
Structural- cross-sectional area and angiogenesis- vascular
remodelling. Functional- control of vascular resistance.
• Improve endothelial function, vascular smooth muscle function,
antioxident systems, heat shock proteins, ↓inflammation.
• While strenuous exercise increases oxidative metabolism and
produces a pro-oxidant environment, regular moderate physical
activity promotes an antioxidant state and preserves endothelial
function.
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• Lowering BP: A bout of afternoon exercise interrupted with short rest
periods is recommended
• After Coronary Bypass: improved exercise capacity associated with
restorations of peripheral oxygen utilization in both patients with and
without Diabetes.
• Congestive Heart Failure: Aquatic exercise improves exercise
capacity and muscle function in patients with the combination of
CHF and DM
• Intermittent Claudication: no improvement observed in experiment
on old women.
• Exercise training: effective antioxidant and anti-atherogenic therapy
• Adverse events observed:12.2% for SBP, 10.4% for TG, and 13.3%
for HDL-C. About 7% of participants experienced adverse responses
in two or more risk factors.
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• Early life stress- maternal separation- ?reversed by exercise
in rats.
• Reduction of depression and fear of falling in older persons by
physical training
• Exercise training resulted in significant improvements in
depressive symptoms, fatigue and aspects of quality of life
• Exercise with integrated cognitive and motor coordination,
may help with preservation of global ability in elders at risk of
cognitive decline – observed in Chinese old subjects
• Other suggested benefits- improved problem solving ability
and feeling of wellbeing
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• Exercise has been recommended for enhancing sleep- 5-6 hours
before sleep time. In animals- exercise increases NREM sleep.
• Six months of training improved sleep in elderly.
• Participation in an exercise training program had moderately
positive effects on sleep quality in middle-aged and older adults.
• Moderate treatment efficacy for the reduction of apnea-hypopnea
index [AHI] in sedentary overweight/obese adults: exercise may be
beneficial for the management of obstructive sleep apnoea
• Exercise seems to improve the mobility, fatigue, and sleep quality in
Stage IV lung and colorectal cancer patients.
• Physical exercise could be an alternative or complementary
approach to existing therapies for sleep problems.
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•
Physical Working Capacity (at HR170) is decreased in luteal and menstrual
phases
•
Strenuous exercise: delayed puberty, luteal phase deficiency, oligoamenorrhea or anovulation – disturbance of GnRH pulsatility due to ?
inadequate energy intake. ?Role of leptin.
•
Hypoestrogenemia: premature osteoporosis. Most cases are reversible with
dietary and exercise modifications.
•
Safe limits of aerobic exercise in pregnancy depend on previous exercise
habits.
•
Pre-eclampsia: improved blood flow, reduced blood pressure, enhanced
placental growth and vascularity, increased activity of antioxidant enzymes,
reduced oxidative stress and restored vascular endothelial dysfunction.
•
Menopausal symptoms- [night sweats, mood swings, and irritability]
reduced by aerobic training.
•
High impact sports activities may produce urinary incontinence
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•
Sexuality enhancement in male subjects (frequency of various intimate
activities, reliability of adequate functioning during sex, percentage of
satisfying orgasms, etc) was proportional to fitness achieved.
•
Reduced / abstenance of sexual activity following cardiac events: fear of
coital death or re-infarction, dyspnea, anxiety, angina pectoris, exhaustion,
depression, loss of libido, impotence, partners anxiety or concern, and
feeling of guilt.
•
Patient that can climb one or two flights of stairs can keep his marital sexual
life without running further risk or even experiencing cardiac symptoms
•
?Risk of Myocardial Infarction during sexual activity is three times higher
[Sex act as acute exercise]
•
Regular exercising- significant protective effect, improved sexual activity
•
Erectile dysfunction in middle-aged men is often improved by physical
activity.
•
Adolescents indulge in sexual activities due to lack of recreation- exercise
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• Prostate cancer: positive benefits for improving
surgical outcomes, reducing symptom experience,
managing side effects of radiation and
chemotherapy, improving psychological health,
maintaining physical function, and reducing fat gain
and muscle and bone loss.
• Increase survivorship by 50%-60% in breast and
colorectal cancers.
• In the wide range of cancer populations, both young
and old, and with curative and palliative intent,
exercise is well tolerated and benefits the patient
psychologically and physically.
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• The proportion of the aged population is increasing
and minor illness will render them dependent
• Exercise training was feasible and effective in reducing
fear of falling and improving dynamic balance and
isometric strength in institutionalized older people with
fear of falling.
• Older women can effectively change the decline in
physical ability associated with aging by exercising.
• The 60-65 year group was capable of converting
physical activity into health benefits in both the short
and long term.
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• There is much evidence that a moderate amount of exercise is
needed for the maintenance of functional integrity of all body
systems.
• It is important for growth and development of children
• Not only can exercise reverse the effects of immobilization, it can
readily produce a further 10 to 20% improvement in strength and
aerobic power, effectively postponing functionally important
thresholds for some 10 to 20 years.
• In the west, regular exercise is rapidly gaining widespread advocacy
as a preventative measure in schools, medical circles and in the
popular media
• In a Medical Faculty in India, of those who were currently
exercising(50%), the proportion of boys was (62%) more compared
to girls (38%). Lack of time, laziness, and exhaustion from
academic activities were identified as important factors for not doing
exercise.
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• 5–17 years:
– at least 60 minutes of moderate to vigorous-intensity
physical activity daily.
• 18–64 years: [in bouts of minimum of10 minutes]
– at least150 minutes of moderate-intensity aerobic
physical activity weekly, or
– At least 75 minutes of vigorous-intensity aerobic
physical activity weekly, or
– an equivalent combination.
• > 64 years:
– as above depending on their abilities and conditions.
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