Kin 310
Exercise/Work Physiology
• Office hours - HC 2910 (lab)
• F 10:30-11:20
– or by appointment (ryand@sfu.ca)
• class email list
– announcements, questions and responses
– inform me of a preferred email account
• class notes will be posted on the web
site in power point each week
– can be printed up to six per page
• lecture schedule along with reading
assignment on web site
• www.sfu.ca/~ryand/kin310.htm
1
Energy for
Exercise
and
Work
Brooks p1-10; ch 4
•
• Astrand ch. 17 p 503-540
• Mcardle, Katch and Katch Appendix D
• Outline
•
•
•
•
Introduction to Exercise Physiology
Course overview
Energy, work and power
Calorimetry and the estimation of
metabolic rate
• Assessment of workload
– Relative VO2, HR, Hormonal response
• Energy expenditure over workday
– Energy systems, work rest ratio
2
Exercise Physiology
• Physiological responses to exercise
depend on
– Intensity, Duration, Frequency,
Environmental circumstances, Diet,
Health, Physiological status
• Exercise requires the conversion of
chemical into mechanical energy
• Principles of bioenergetics control
and limit performance
• Acquisition and utilization of energy
and the role of organ systems in
supporting these processes will be
discussed
• Understanding short (acute) and
long term (chronic) effects of
exercise on the human machine is
important in exercise science and
health
3
Rate Limiting Factor
• What limits performances?
• Proper analysis of a sport or work
situation is important to identify;
– Pathways and metabolic sequences that
are used
– The factors which turn the rate of these
pathways up or down
– The steps that are limiting or slow
• All of this is required to
understanding function,
pathophysiology (disease) and to
concentrate efforts when training to
improve performance
• Eg. VO2 fig 1-5
• Limited by cardiovascular system
• Widely used criterion of physical
fitness
4
Performance
• Stress and Response
• With appropriate stimuli,
physiological systems respond with
increased functional capacity
(training)
• Overload but not overtrain
• Seyle - General Adaptation
Syndrome (GAS)
– Alarm Reaction (shock)
– Resistance Development (adaptation)
– Exhaustion (staleness)
• Principles of Fitness
–
–
–
–
Overload
Specificity
Reversibility
Individuality
5
•
•
•
•
•
•
•
•
•
•
Course
Overview
Discussion of the physiological basis of exercise
and work
Evaluating Energy and Workload
Cardiovascular and respiratory compensations and
capacities
– Limitations and adaptations to training
Cellular bioenergetics
– Providing ATP to meet demand and recovery
Fatigue - inability to sustain activity level
– description of fatigue in the CNS, the
neuromuscular junction and the muscle cell
Molecular level adaptation
– activity changes the cellular environment stimulating adaptation to better meet demand
Work place / sport analysis and assessment of
worker /athlete capacity
Strength evaluation variables
Ageing - change in physiological capacities impacts of disease and activity level
Exercise and the Environment
– Heat and barometric pressure can create
additional demands on physiological systems
6
Energy
• Energy - capacity or ability to perform
work - joules, calories
• Work - application of a force through a
distance - joules, calories, Kg*m
• Biological work - transport, mechanical
and chemical work
• Power - amount work performed over a
specific time (workrate) - Joules/s; kg*m
*min-1
• Transformation of energy - forms of
energy can be converted from one form to
another
– chemical energy in food is transformed into
mechanical energy of movement or other
biological work
– Biological energy cycle
7
Metabolism
• Metabolism - the total of processes
occurring ina living organism
– Because heat is produced by these
processes, the ‘metabolic rate’ can be
measured by the rate of heat production
• Ultimately, all metabolic processes
depend on biological oxidation
• Measuring O2 consumption is a good
estimate of heat production, or
metabolic rate
• Energy Transduction
– Photosynthesis
– cell respiration (*not ventilation*)
– cell work
8
Calorimetry
• Calorie - heat energy required to
raise one gram of water one degree
Celcius
• Calorimetry - procedure to measure
metabolic rate
– Direct Calorimetry - measurement of
heat - very difficult
– Indirect Calorimetry - measurement of
Oxygen use - valid and reliable
• Fig 4-8 Atwater and Rosa
– Determined heat production, oxygen
consumption and carbon dioxide
production simultaneously
– Established relationship between direct
and indirect methods
• Bomb calorimeter - energy value of
food when ignited - fig 4-9
• Appendix D - Mcardle, Katch and
Katch (on resreves)
9
Respiratory Quotient
• Table 4.1 - energy per unit oxygen
different - carbohydrates 6.4 %
higher
• Respiratory Quotient - Ratio of CO2
produced to O2 consumed
• Value obtained gives an indication of
the type of fuel being used in muscle
– Pure Glucose RQ = 1.00
– Pure Fat RQ = .70
– Mixed fuel will provide intermediate
value depending on mix
• Fig 4.10 marathon RQ values
• R value - an estimate of RQ that is
measured at the mouth
– Must consider non-metabolic sources
of CO2 - Fig 4-14
10
Measurement of
Metabolic Response
• Evaluation provides info about absolute
and relative intensity of exercise bout (fig
10.1a)
–
–
–
–
absolute VO2 (L/min or ml/Kg/min)
% of VO2 max
% of HR max
multiples of Metabolic Rate (MET’s)
• 1kcal/Kg/hour at rest; 3.5mlO2/kg/min
• determination of metabolic response
allows estimation of
–
–
–
–
Total energy cost
Nutritional requirements
Efficiency calculations
Estimation of workload indicates metabolic
system utilization, and the potential for fatigue
11
Work Load Assessment
• Assessment of work load in relation
to work capacity
– variability in capacity
– variability in response
• expression of workload by absolute
VO2 alone is almost meaningless
• Need work load as % of individual max
• Assessment requires the determination of ;
– individual VO2 max
– VO2 requirement of imposed load
– assessment of muscle groups being utilized, and
the % of their maximum strength -to determine
fatigue onset
12
Assessment
• Maximal aerobic power
– direct - VO2 max test
– estimation - predictive tests
• Assessment of Workload
– measure O2 uptake during work
• Fig 17-2 O2 uptake vs bike/work
– portable devices, rapid analysis of
VCO2 and VO2 - large data base
– field studies - collect expired air
• Douglas bag
– or - use flow meter to determine
volume of air, and take samples of air
for content analysis
• Fig 17-3 commercial fisherman
– subjects often affected - test atypical
– Eg. Breathing through mouth not nose
13
Indirect assessment
• Recall linear relationships between
HR and VO2, VO2 and work rate
– HR may be used to estimate workload on individual basis
– same muscle groups environmental
temperature, and emotional stress
• Continuously recorded HR
– provides general picture of overall
activity level during entire day
– along with time activity studies
collected by observers
– possible to separate different activities
with respect to HR
– Fig 17-5 - fisherman
14
Comparison studies
• Fig 17-6 - strong day - day consistency
• Computer analysis of HR data gives;
– mean values, peak values, distribution
and HR variability
• Fig 17-8 comparison of direct vs
indirect measurement +/- 15 %
• HR is good estimate of workload
when work uses large muscle groups
• Fig 17-9 arm vs leg work
– HR is higher in arm work than leg work
for the same work load.
• O2 uptake for work load must be
expressed as % max of individual
– indicates relative degree of exertion
• HR reserve (HR max - HR rest)
– Circulatory strain is best expressed as a
percentage of an individuals HR reserve
15
Stress of Work
• The total stress imposed on the organism
by a given work situation (physical or
psychological) is generally reflected by
nervous and hormonal stimulation
– Proportional to the degree of stress
• Nervous Response
• Inc sympathetic tone - inc HR
– influence linear relationship
– Eg HR vs workload
• Hormonal response
– total stress reflected by sympathetic
response
– Measure ep and/or nor ep with urinary
excretion or blood samples
• Fig 17-16, 17-17 - Catecholamines - inc
with standing, cold and emotion
– Also inc with duration and severity of
muscular exertion
16
Energy Expenditure
• Need to establish practical limits for
physical work loads
• Type of work and work/rest cycles
are important
• Large individual differences in
physical work capacity
– 30 - 40% VO2 max for 8 hour day
– 40 % of max strength in repetitive
muscular work;
• rest:work ratio of ; 2:1
• physiological and psychological
responses influenced by
–
–
–
–
–
–
individual max aerobic power
size of muscle being engaged
working position
Static or dynamic work
intermittent vs continuous activity
environmental conditions
17
Daily Energy Expenditure
• Important for
– calculation of energy needs
– determine physical activity of groups
– role of physical activity in health
• Methodology
– 24 hr recorded HR
– time activity data
– assessment of daily energy intake to
maintain body weight
– all fairly accurate +/- 15%
• show large individual variability
– 1300-5000 kcal /day
• Table 17-1, 17-2
18
Energy expenditure
• O2 uptake and HR - Table 17.1
• Important for ;
– Calculation of energy needs
– Determine physical activity of groups
– Role of physical activity in health
• Methodology All fairly accurate +/- 15%
– 24 hr recorded HR ; Time activity data
(video analysis)
– Assessment of daily energy intake to
maintain body weight
• Wide individual variability in energy
output - Table 17-1,2
–
–
–
–
Occupation
Leisure activity / Physical activity
Environmental temp
Daily rate 1300 - 5000 kcal
• Reg active male 2900 kcal/day
• Reg active female 2100 kcal/day
19
Energy Expenditures
•
•
•
•
•
•
•
•
•
Work expenditures
Most light work < 5 kcal /min
Some physical jobs 7.5 - 10.5 kcal/min
Permissible limits for daily work 20002500 kcal
Limits are difficult due to individual
differences in work capacity or fitness
Individuals will usually self regulate the
rest pauses
Peak load is more important than mean
energy expenditure
You can attain a higher 8 hour energy
expenditure if the work is consistent and
does not have peak loads
Basal Metabolic rate (BMR) - rate of
energy metabolism in a resting individual
14-18 hours after eating
20
Energy Expenditure
• Recreational activities
• McArdle, Katch and Katch
– Appendix C (on reserves)
• Different activities have different
energy expenditures
–
–
–
–
–
Cycling race
Golf
Skiing uphill fast
Swimming -fast
Running 5:30 mile
13 kcal/min
6 kcal/min
21 kcal/min
13 kcal/min
22 kcal/min
• Individuals do activities at different
intensities
• Must take body weight into account
21