KPE264 - Module 3

• During maximal exercise, energy contribution is either aerobic or anaerobic, with no blending.

Energy Systems Contribution

• ATP-PC dominates at the start but quickly declines
• Anaerobic lactate increases and then plateaus
• Aerobic O2 rises steadily and accounts for most energy after ~2 minutes

Effects of H+ and Temperature

• High H+ concentrations and temperature inhibit PFK
• This affects X-bridge binding
• Can be altered with creatine supplementation
• Use bicarbonate and temperature to buffer H+

Fuel Use During Maximal Exercise

• Phosphagen system dominates in the first ~5 seconds (85%), 40m dash
• Glycolytic increases around ~30 seconds (50%), Wingate test occurs
• Oxidative system becomes dominant around ~5 minutes (80%), 1500m run completed
• Prolonged exercise relies almost entirely on oxidative system ~3 hours (99%), marathon distance occurs

Anaerobic Exercise Response

• Wingate bike test measures anaerobic performance
• Consists of a 30-second all-out test against high break force equal to 0.075kg/kg of body mass resistance

Wingate Bike Test Measurements

• Peak power (first 5 seconds)
• Mean power (entire 30 seconds)
• Fatigue index (% decline in power over the entire test)

Power and Exercise Type

• High peak power is indicative of powerlifting
• Mean power is indicative of distance running and hockey

Total Anaerobic Energy Production from Biopsies

Calorimetry

• Measurement of aerobic metabolism
• Quantification of energy production is achieved directly or indirectly

Direct Calorimetry

• Involves measuring heat production
• Assumes a proportional relationship between temperature and energy production
• 1 kcal increases the temperature of 1 kg of water by 1 degree Celsius

Indirect Calorimetry

• Measures oxygen utilization at the mouth
• O2 uptake of 1L is equivalent to 5 kcal of expanded energy
• Fuel use can be also determined if CO2 production is measured

Respiratory Exchange Ratio (RER)

• Ratio of CO2 produced to O2 consumed
• RER = VCO2/VO2
• A constant amount of O2 is required to combust each unit of food
• The amount of O2 needed differs between carbs and fats

Glucose and RER

• C6H12O6 + 6 O2 → 6 CO2 + 6 H2O
• VCO2/VO2 = 6/6 = 1
• 32 ATP/6 O2 = 5.3
• Carbs are more O2 efficient

Palmitate and RER

• C16H32O2 + 23 O2 → 16 CO2 + 16 H2O
• VCO2/VO2 = 16/23 = 0.7
• 106 ATP/23 O2 = 4.6 (ATPs/unit of O2)

RER Applications

• Allows determination of the "fuel mix" of CHO and Fat
• 1L O2 consumed = 5 kcal burned
• High RER indicates carbs being oxidized for energy
• Fasted state results higher RER's of 0.7+

RER Limitations

• Hyperventilation where expelled CO2 is not from metabolism can impact results
• Intense exercise results in increased CO2 not from substrate oxidation

Oxygen Uptake

• Refers to the rate of O2 utilization by the body
• VO2 = volume of O2 consumed per min expressed: L/min or mL/min (absolute), mL/kg/min (relative, in body mass)
• Average resting VO2 = 0.2-0.3 L/min or 250 ml/min
• 3.5 ml O2/kg/min → 1 MET (“metabolic equivalent”)

Resting VO2: Estimating Energy Expenditure

• Assume VO2 = 3.5 ml O2 / kg / min:
  • e.g., 70 kg person → 245 ml / min → 0.245 L/min
  • 1 L O2 ≈ 5 kcal, 1.23 kcal/min, ≈ 1770 kcal / day
• Alternatively, measured VO2 = 250 ml O2 / min
  • 0.25 L/min
  • 1.25 kcal / min
  • 1800 kcal / day

VO2 Max Values

• Consider a 60 kg female and 80 kg male

Measurement of VO2 Max

• VO2max is the point when ATP is in demand and O2 consumption is maximized
• Trained athletes don't always see a plateau and are used to working through discomfort
• Plateau, is a vital risk sign of CV health
• Unaccustomed may not reach plateau and are unable to push to reach plateau

Criteria for determining VO2 max

• Plateau in VO2 demonstrated, often termed VO2peak if criterion #1 not satisfied
• Reach age-predicted max HR
• High blood lactate – 8x rest
• RER > 1.1
  • Hyperventilation (may reach @ end of exercise) and samples of H+, more CO2 is expelled (not reflective of mitochondria)
• Voluntary exhaustion (choosing to stop

Oxygen Uptake: "Rest-Work Transition"

• O2 consumption:
  • Gradually increases
  • Point where O2 does not meet demand.
  • Oxygen deficient... rectified w/ anaerobic sources. Rely on anaerobic system @ onset of activity
  • O2 demand > O2 consumed (really early in exercise)

Lactate Threshold

• Exercise intensity where there is an abrupt increase in blood lactate
  • Reflects ability to sustain oxidative metabolism, and is an anaerobic threshold
  • Higher VO2 max allows closer work to max

Factors Affecting Muscle Lactate

• Oxygen availability
• Enzyme activity
• Muscle fiber type
• Muscle lactate transporters
• Sympathetic nervous system activity

Lactate Threshold (LT)

• Is the ability to sustain aerobic activity

Characteristics of Successful Endurance Athletes

• High VO2 max
• High lactate threshold (as % VO2 max)
• High economy of effort
• High percentage of type I muscle fibers
  • Sub max intensity is more economical to meet ATP demands
• Less economical is better to have good technique, don't waste energy

Lactate Threshold & Endurance Performance

• The following two athletes have the same VO2max Left person is quicker and works at higher pace (race pace)

Economy/efficiency (O2 uptake, some measurement of work) of effort

• Greater economy of effort can be demonstrated by:

1. More work performed for a given energy cost OR
2. Lower energy cost for a given amount

Fuels for Exercise

• Muscle glycogen
• Blood glucose (from liver)
• Muscle triglyceride
• Blood fatty acids (from adipose tissue)

Effect of Exercise Intensity on Fuel Selection

• Plasma FFA decrease and increases in muscle glycogen occur
• Blood glucose remains constant
• Best exercise intensity to burn fat/weight loss occurs at low to moderate intensity (25%)
• Consistent rate of energy expenditure

All Fuel Increase besides Muscle

• Increase intensity leads to rely on carbs for more O2 efficiency

Factors Effecting

• Trained vs untrained have better using fat
• Difference between male/female- oxidize well

VO2max for KPE Student

• VO2max of 4.0 L/min

Assume the student exercises for 30 min

• Intensity (% VO2max) |Intensity|( kcal)|VO2max Energy from Fat|% Energy from CHO|Rate of Energy Use |Total |--- |--- |--- | ---|--- |--- | | 25% | 70% |30% |55kcal |75 min | 50% |50% |50% |10 kcal |150| |75% |30% | 70% |150 kcal|315min |

Effect of Exercise Duration on Fuel Selection

• Decline in limited stores of Muscle Glycogen occurs

How to Research

• By measuring overall rate of energy use (VO2)
• Determine % CHO and fat use (RER) -Measure muscle glycogen utilization (biopsy)
• "other" CHO = blood glucose help determine carbohydrate break down
• Measure muscle uptake of FFA (A-V catheters) a. "other" FAT = muscle TG

Estimating RER

• RED - athlete begins test in morning after overnight fast
• BLUE - athlete has eaten pancakes, strawberries and orange juice 2 hrs before test

Neurons in Blood Work

• Relative contribution of of fat (%) occurs
• Releases hormones into bodily fluids to take specific effects

Classifications

• Releases steroids from the membranes -Not lipid solvable -Derivded from lipid (cholesterol)
• Releases hormones from the liver-Lipid soluble → can cross cell membranes which alters the production
• Alters enzyme activity or the membrane trasport

Major Hormones

• Alters membrane activity or their protein
• Insulin can effect more
• Nor/epinephrine glycogen phosphorolysis

How to Determine Hormone effect

2 Types

• GL
• NE
• Epi

Mobilization

• Recretes proteins and activate enzyme activity
• Overall time- ≤1 min
• Cellular response

Diabetes

• Inactivity of blood, less bloodflow
• Body produces more induli

Muscle Uptake

• Glucose upate increases the intake of more -Allows the most insulin delievered to muscles
• Causes the glucose and blood concentrate
• More insulin signal is directed where glocuse is needed

CHO

-Increases in CHO but is low in the blood

• Increases in Skeletal muscle when feeting and during heavy exercise
• Reductions increase the fat stores and are difficult to control

Adaptations

• Helps mobilize the fuel during exercise

• Increases the glucose uptake

• Glucogon activity increase during HSL

• Helps create energy during muscle movement

• Stimlate the muscle and liver movement with the help of glucose and glucagon

• Helps mobilize the fuel by being effective during exercise

• Helps the muscle glucsose by taking up insulin -Helps to support Glucose by increaseing energy production during HSL

Mitrochondrias

• key adaptations to training
  • Helps with the enyme, oxidative system and the muscle movement
• Fuel storange
• Incerases the glycogen and muscles
• Cho usse decreases in the body to create more training by Decressing the ATP

Minmizes

• It minminzes glucosue by using less energy and blood cells
• more efficeit energy and no gluose

Mitochondria

• • More trained and is found in varibles during more Mitochondria

Performance

• Deacreae resistance at give work loods

Why its important

-Because it reduces workload and it decreases the blood and energy it delivers

These exercise physiology questions cover key concepts like VO2 max, lactate levels, economy of effort, and fuel selection during endurance events. They also address the impact of the lactate threshold and factors affecting the respiratory exchange ratio (RER). These questions aim to test understanding of physiological adaptations and metabolic responses to exercise.