Lecture 10 Flashcards
Economy of movement:
Energy required to maintain a constant velocity of movement
Requires evaluation of the vo2 during ex at a constant power output or velocity
*only applies to steady-rate ex where vo2 closely mirror energy expenditure
takes on added importance during longer-duration ex
Mechanical efficiency:
Relates the amount of energy required to perform a particular task to the actual energy requirement of the work accomplished
Reflects the % of total chemical energy expended that contributes to external work, with the remainder lost as heat
Mechanical efficiency (%) =
External work accomplished / energy expenditure x 100
Efficiency of humans for mechanical work is…
Below 100%
The energy required to overcome internal and external friction is the largest affecting factor
Efficiency avgs b/w…
20-25% for walking, running, and stationary cycling
falls <20% for activities with substantial drag force
Cardiorespiratory fitness:
The ability to perform large muscle, dynamic moderate to high intensity ex for prolonged periods*
Reflects functional capability to deliver o2 & remove metabolic by-products during ex (heart, blood vessels, blood, lungs, relevant muscles)
Cardiorespiratory fitness affects numerous physiological responses…
At rest, in response to submaximal ex, in response to maximal ex, during prolonged work
CR fitness aka
Max o2 uptake/consumption, CV endurance/fitness/capacity, etc.
Why is CR fitness considered health related?
1 decrease CR fitness associated with increase risk of premature death from all-cause, specifically CVD
2 increase CR fitness associated w/ reduction in death from all cause
3 *most functional activities are aerobic in nature
4 increase CR fitness associated with increase habitual PA
Criterion measure of CR fitness =
Maximal aerobic power (vo2max)
*Why is vo2 important for endur activities?
1 vo2max represents the upper limit of aerobic ex tolerance – the max rate of o2 deliver to working muscles
2 endur activities are performed at some fraction of vo2max
3 if vo2max is low then level of endur performance will be limited
Determinants of max oxygen uptake vo2max
Max Q – max HR, max SV
Max systemic a-vo2 difference – max arterial o2content, minimal mixed venous o2 content
Central factors
Pulmonary diffusing capacity, Q, o2 carrying capacity
Peripheral factors
Skeletal muscles
Central mechanisms (o2 transport)
Increase SV Increase total blood volume & Hb Decrease myocardial o2 cost Increase ventilatory efficiency (lungs) Increase pulmonary diffusing capacity (lungs)
Peripheral mechanisms (o2 utilisation)
Increase mitochondria (density & size)
Increase aerobic enzymes (SDH, MDH, CS)
Increase capillaries
Other factors (o2 transport/utilization)
Increase glycogen storage
Increase free fatty acids storage
Type IIb -> type IIa, hypertrophy type I
Increase blood lactate recycling
Normative vo2max – female 20
Good = 33.0-36.9 Superior = >41.0
Normative vo2max – male 20
Good = 42.5-46.4 Superior = >52.4
Calculating vo2
Vo2 = (volume inspired air x fraction of oxygen in the inspired air) – (volume of expired air x fraction of o2 in expired air)
Test/ex requirements to elicit vo2 max:
Sufficiently large muscle mass
Dynamic ex
Incremental ex
Maximal exertion *
Criteria for a maximal test:
HR +/- 10bpm of age-predicted maximum
A plateau in vo2 (\8-10mmol/L
RER > 1.10
RPE>17
Max ex test pro
Direct measurement of max o2 uptake
Diagnosis of cardiovascular disease
Max ex test con
Discomfort for client
Increased risk and need for medical supervision
Two fundamental r/ships allow indirect predictions of vo2max:
A linear r/ship b/w vo2 and mechanical power
A linear r/whip b/w vo2 and HR according to the fick equation
Sub-max ex tests to predict vo2 pros
Improved client comfort
Increased safety
Sub-max ex tests to predict vo2 cons
Based on assumptions
Accuracy based on assumed normative values
Conducting the test – steps:
Explain test Safe use of treadmill Familiarity w/ equipment * Use of handrails What can they expect to experience?* What do they need to tell you? When does test end? Clothing Eating drinking Prescription drugs*
What are termination criteria for VO2 test?*
What are termination criteria for VO2 test?*
