Bio-energetics
Name the rate limiting enzymes for the ATP-PC system, glycolysis, Krebs Cycle, and the ETC.
Creatine Kinase
PFK
Isocitrate Dehydrogenase
Cytochrome Oxidase
A marathon runner “hits the wall” after several hours of exercise. Which stored fuel has become severely depleted?
Glygogen
At the onset of exercise, ATP demand increases immediately but VO₂ rises gradually. What term describes the energy demand temporarily supplied by anaerobic pathways before steady state?
Oxygen deficit
A trained and untrained individual complete the same graded exercise test. Who typically reaches lactate threshold at a higher percentage of VO₂max?
Trained individual
During exercise, insulin decreases but contracting skeletal muscle can still increase glucose uptake. Which transporter moves to the muscle membrane?
GLUT4
What are the ATP equivalents for NADH, FADH2 and GTP?
NADH (2.5 ATP), FADH2 (1.5 ATP) and GTP (1 ATP)
During prolonged exercise, the liver can produce new glucose through gluconeogenesis. Name THREE molecules that can enter this pathway.
Lactate, glycerol, amino acids
During a graded exercise test, a subject reaches exhaustion without a clear VO₂ plateau. Name THREE secondary criteria that could support that VO₂max was achieved.
High RER
Near-max HR
High Blood Lactate
(High RPE)
As exercise intensity increases, blood lactate and which ion tend to rise together?
H+
After epinephrine binds its membrane receptor, what protein activates adenylate cyclase to begin the second-messenger pathway?
G protein
List the NET products of glycolysis from one molecule of blood glucose.
2 ATP + 2 NADH + 2 pyruvate
Exercise intensity rises above ~70% VO₂max and the body shifts toward greater carbohydrate use. Name this concept.
Crossover
An athlete exercising at steady state has an RER of 0.77. Which fuel is primarily being oxidized? What would an RER of 1.00 indicate?
0.77 = mostly fat
1.00 = completely carbohydrate
High lactate concentrations inhibit which enzyme responsible for stimulating triglyceride breakdown in adipose tissue?
HSL
During prolonged or high-intensity exercise, which catabolic hormone mobilizes amino acids and FFA while also stimulating gluconeogenesis?
Cortisol
During intense exercise, glycolysis is producing NADH faster than its electrons can enter the mitochondria. Name the TWO products formed when pyruvate accepts the hydrogens/electrons from NADH.
Lactate & NAD⁺
Lactate produced by working muscle can be transported to the liver and used for gluconeogenesis. Name this lactate–glucose pathway.
Cori cycle
Which portion of EPOC is associated with elevated body temperature, circulating hormones, and increased HR and ventilation after exercise?
Slow Portion
High-intensity exercise increases lactate, which inhibits HSL and reduces fat mobilization. Which metabolic process is therefore reduced?
Lipolysis
Name the FIVE hormones that can activate hormone-sensitive lipase during exercise.
Epinephrine, norepinephrine, glucagon, cortisol, growth hormone
Trace a fatty acid to aerobic ATP production: Where does β-oxidation occur, what does the fatty acid become, and which TWO products carry its electrons to oxidative phosphorylation?
Mitochondria → Acetyl-CoA → NADH + FADH₂ → ETC
During high-intensity exercise, fat oxidation decreases even though plenty of fat is stored in the body. Give TWO physiological reasons why.
↓ adipose blood flow + ↑ carbohydrate metabolism
Which TWO major recovery processes occur during the rapid portion of EPOC?
ATP-PC restoration + O₂ replenishment
As lactate and H⁺ rise during high-intensity exercise, the muscle becomes increasingly dependent on which fuel?
Carbohydrate
Which TWO adrenergic hormones increase during exercise and help maintain blood glucose by stimulating liver glycogen breakdown while also promoting fat mobilization?
Epinephrine & Norepinephrine