Aerobic Testing - Exsc Testing

Rockport Walk Test - Physiological Rationale

• Field test

• Minimal equipment

• Application to large groups

• Ease of administration

• Highly effective option to a lab test

Rockport Walk Test Population Uses

• More appropriate test for use in sedentary persons and older adults

RPWT Procedures

• Measure and record participants basic data

  • Age

  • Height

  • Weight

  • Gender

• Participant walks on level terrain for 1 mile has fast as possible

• HR recorded immediately after the 1 mile test has been completed

• Estimate VO_{2 MAX}

VO_{2 MAX} Estimate

• 132.853 + (Gender x 6.315) - (age (y) x 0.3877 - (weight (kg) x 0.1692) - (walk time (min) x 1.4537) - (HR (bpm) x 0.1194)

• Gender

  • Male = 1

  • Female = 0

VO_{2 MAX} Test

• Directly measures oxygen uptake through the collection of exhaled air during exercise to fatigue

• Best laboratory test of aerobic fitness

  • Reflects training status of tissue

  • More highly trained tissues = more O₂ transport/extraction = higher VO_{2 MAX}

Factors Affecting Consumption of Oxygen (VO₂)

• CV and respiratory system ability to transport and supply oxygen

  • cardiac output

• Ability of skeletal muscles to extract and use oxygen

  • reflected by arteriovenous oxygen difference (a-vO_{2 DIFF)}

Limiting Factors of VO_{2 MAX}

• Low ability to transport and supply oxygen

  • Strength or training of the heart (left ventricular muscles)

  • Low capillary and mitochondrial density

  • Small size of mitochondria

• Genetics

• Enzymes

  • Pyruvate dehydrogenase limited inability to make Acetyl CoA to extract H⁺ in the citric acid cycle

a-vO_{2 DIFFERENCE} and Exercise

• Resting

  • Smaller difference between blood in arteries and veins

• Maximal

  • Large difference dur to larger PO₂ gradients and lower O₂ affinity of hemoglobin

• Due to increase in

  • Capillary and mitochondrial density

  • Size of mitochondria

Where does aerobic metabolism occur?

Mitochondria

Citric Acid Cycle

• Uses Acetyl CoA to pull H⁺ from the intermediary molecules and electrons

• Electrons transported by CoA in the inter-membrane to and power the protein channels

• With channels open H⁺ molecules are pushed through the electron transport chain and enter the inter-membrane space

• Food or nutrients are consumed and through the Active Protein Channel H⁺ in the IMS pushed through

• In APC ADP and Pi combine and form ATP

• With H⁺ entering channels to IMS, Cyt C in IMS moves through and electrons attach to O₂

• O₂ is then utilized

VO_{2 MAX}

• Maximal oxygen consumption

  • Highest possible value attained during a max effort graded exercise test using a large muscles mass

VO_{2 PEAK}

• Peak oxygen consumption

Conditions Used During VO_{2 PEAK}

• Exercise test using different modes elicit different oxygen consumption values

  • Running vs Cycling

• Symptoms or lack of motivation limit the participants ability to reach a physiological maximum

Mode Specificity

• Best use a mode that stimulate the type of movement participant is training in

  • Running = treadmill

  • Cyclist = cycle ergometer

  • Rowers = rower

  • Swimmers = swim fume

• Adaptations occur only in specifically trained muscles

  • Heart = systemic adaptation

  • Can’t expect a difference if you are using a different mode specificity

Exercise Protocol

• Test is a continuous graded exercise protocol to exhaustion

  • Submaximal

  • Maximal

  • Supra maximal

    • Contributes to exhaustion and combines aerobic and aerobic systems

• (MISSING SLIDES 17-22)

Respiratory Exchange Ratio (RER)

• VCO₂/VO₂

• 3.75 L/min / 3.35 l/min = 1.12

RER Reflections (DNF)

• Intensity

  • RER at rest = 0.7-0.75

  • Moderate intensity exercise = 0.85-0.9

  • Maximal intensity exercise = 1.10-1.20

• Fuel Usage

  • 0.7 = 100% fat

  • 0.85 = 50% fat, 50% CHO

  • 1.00 0r above = 100% CHO

Ventilatory Threshold

• Describes point where ventilation increased disproportionately relative to increases in VO₂ and workload

• Ventilation increases linearly with VO₂ until pass the lactate threshold

  • 20-25 L of air breathed for every 1 L of O₂ consumed

    • An RER above 1.0 indicates there is an accumulation of lactate

    • Increasing ventilation during intense exercise is from increase in CO₂ when lactate buffering

    • RER > 1.00 is achieve by increase in CO₂

Lactate Buffering

• Breathing rate increases indicating an accumulation of lactate

• Produced carbonic acid which is then degraded to water and carbon dioxide

• CO₂ can be exhaled

• Causes increases in CO₂ and RER

Energy Expenditures (kcal/min)

• Estimated from oxygen consumption by the process of indirect calorimetry

• ~5 kcals of energy is expended for every 1 L or O₂ consumed

• VO₂ L/min x 5.0 kcal/L

  • 3.35 L/min x 5 kcal/L = 16.8 kcals/min

Absolute Oxygen Consumption

• Difference between volume of oxygen inhaled and the volume of oxygen exhaled

• V_iO₂ and V_EO₂

Relative Oxygen Consumption

• Variable is used to describe an individual fitness level

• Convert L/min to mL/min and then divide by BW (kg)

• Relative VO₂ = (3.35 L/min x 1000) / 80 kg = 41.9 mL/kg/min

VO_{2 MAX} Test-Related Variables

• Energy expenditures

• Absolute oxygen consumption

• Relative oxygen consumption

How to increase transport, extraction, and utilization of O₂

• Exercising at 50-80% of VO_{2 MAX} or HR can improve capillarization through prolonged periods of stretching on capillaries

  • Enhances the diffusion of oxygen and improve the exchange of waste materials and nutrients

• Exercising at 150% of VO_{2 MAX} for 1 min with 3 mins rest

  • Increase in capillaries surrounding both fiber types

  • Seems to short-term with no further changes after 4 weeks