Exercise Physiology

Exercise Physiology Indian Medical PG Question 1: An adolescent male patient presents to you with exercise intolerance. He gives a history of developing cramps on exertion. Which of the following enzyme deficiencies could be the cause?

• A. Myophosphorylase (Correct Answer)
• B. Hexokinase
• C. Glucose-6-phosphatase
• D. Hepatic glycogen phosphorylase

Exercise Physiology Explanation: ***Myophosphorylase*** - A deficiency in **myophosphorylase** (McArdle's disease, Glycogen Storage Disease Type V) impairs muscle glycogen breakdown, leading to **exercise intolerance** and **muscle cramps** due to insufficient ATP production during exertion. - Patients often experience a "second wind" phenomenon where symptoms improve after resting, as free fatty acids become an alternative fuel source. *Hexokinase* - A deficiency in **hexokinase** would affect the first step of glycolysis, impacting glucose phosphorylation in all tissues, not specifically causing exercise-induced muscle cramps. - This deficiency is rare and typically presents with **hemolytic anemia** due to impaired erythrocyte metabolism. *Glucose-6-phosphatase* - A deficiency in **glucose-6-phosphatase** (Von Gierke's disease, Glycogen Storage Disease Type Ia) primarily affects the liver and kidneys, leading to **fasting hypoglycemia**, lactic acidosis, and hepatomegaly, not exercise intolerance. - Muscle glycogen metabolism is unaffected in this condition. *Hepatic glycogen phosphorylase* - A deficiency in **hepatic glycogen phosphorylase** (Hers' disease, Glycogen Storage Disease Type VI) mainly causes **hepatomegaly** and **mild hypoglycemia** because the liver cannot effectively mobilize its glycogen stores. - **Muscle glycogen metabolism** remains normal, so exercise intolerance and cramps are not characteristic symptoms.

Exercise Physiology Indian Medical PG Question 2: What are the products of the isocitrate to α-ketoglutarate conversion in the TCA cycle?

• A. GTP, CO2
• B. NADPH, H2O
• C. FADH2, ATP
• D. NADH, CO2 (Correct Answer)

Exercise Physiology Explanation: ***NADH, CO2*** - The conversion of **isocitrate to α-ketoglutarate** is an oxidative decarboxylation step catalyzed by **isocitrate dehydrogenase**. - This reaction produces **NADH** (from NAD+) and **carbon dioxide (CO2)**, as a carbon atom is lost. *GTP, CO2* - **GTP** is produced during the conversion of **succinyl-CoA to succinate** in a substrate-level phosphorylation step, not during the isocitrate to α-ketoglutarate conversion. - While CO2 is produced in the latter, GTP is not. *NADPH, H2O* - **NADPH** is primarily generated in the **pentose phosphate pathway** and is used for reductive biosynthesis, not directly produced in the TCA cycle. - **H2O** is consumed or produced in other steps of the TCA cycle but not as a direct product of this specific reaction. *FADH2, ATP* - **FADH2** is produced during the conversion of **succinate to fumarate** by succinate dehydrogenase. - **ATP** (or GTP which can be converted to ATP) is produced in the succinyl-CoA to succinate step, not at the isocitrate dehydrogenase step.

Exercise Physiology Indian Medical PG Question 3: Which of the following is NOT required for gluconeogenesis from lactate?

• A. Transamination of pyruvate to alanine (Correct Answer)
• B. Transport of lactate from muscle to liver
• C. Conversion of lactate to pyruvate
• D. None of the above

Exercise Physiology Explanation: ***Transamination of pyruvate to alanine*** - While **alanine** can be a substrate for gluconeogenesis, **lactate** is directly converted to pyruvate, which then enters the gluconeogenesis pathway. **Transamination to alanine** is not a required intermediate step for lactate-derived glucose production. - The direct conversion of **lactate to pyruvate** by **lactate dehydrogenase** is the key initial step, not its conversion to alanine. *Transport of lactate from muscle to liver* - **Lactate** produced in muscles (e.g., during intense exercise) must be transported to the **liver** via the bloodstream to be used for **gluconeogenesis** in the **Cori cycle**. - This transport is essential for clearing lactate from the periphery and supplying the liver with a gluconeogenic precursor. *Conversion of lactate to pyruvate* - **Lactate dehydrogenase** catalyzes the reversible conversion of **lactate to pyruvate**, which is the critical first step in converting lactate into a gluconeogenic substrate. - This reaction regenerates **NAD+** (not NADH), which is necessary for glycolysis to continue in muscle tissue. *None of the above* - This option is incorrect because there IS a step listed above that is not required: **transamination of pyruvate to alanine** is indeed not necessary for gluconeogenesis from lactate, making Option A the correct answer to this "NOT required" question.

Exercise Physiology Indian Medical PG Question 4: During heavy exercise the cardiac output (CO) increases up to five fold while pulmonary arterial pressure rises very little. This physiological ability of the pulmonary circulation is best explained by

• A. Large amount of smooth muscle in pulmonary arterioles
• B. Increase in the number of open capillaries (Correct Answer)
• C. Sympathetically mediated greater distensibility of pulmonary vessels
• D. Smaller surface area of pulmonary circulation

Exercise Physiology Explanation: ***Increase in the number of open capillaries*** - During heavy exercise, the significant increase in cardiac output is accommodated by the **recruitment of previously closed pulmonary capillaries**. - This recruitment, along with **distension of existing capillaries**, reduces overall pulmonary vascular resistance, allowing blood flow to increase without a substantial rise in pulmonary arterial pressure. *Large amount of smooth muscle in pulmonary arterioles* - While pulmonary arterioles do contain smooth muscle, their primary role is in **regulating regional blood flow** and response to hypoxia, not facilitating large increases in overall blood flow during exercise. - The pulmonary circulation is characterized by **low resistance** and high capacitance compared to the systemic circulation, meaning it has less smooth muscle tone at baseline. *Sympathetically mediated greater distensibility of pulmonary vessels* - The pulmonary vasculature has **limited sympathetic innervation** compared to systemic vessels, and sympathetic activity plays a minor role in its distensibility during exercise. - Changes in pulmonary vascular resistance during exercise are primarily due to **mechanical factors** (recruitment and distension) rather than neurogenic control. *Smaller surface area of pulmonary circulation* - The pulmonary circulation actually has a **vast capillary surface area** crucial for efficient gas exchange. - A smaller surface area would lead to **higher resistance** and a greater pressure increase for a given flow, which contradicts the observation during exercise.

Exercise Physiology Indian Medical PG Question 5: Which of the following parameters is most critical for maintaining optimal oxygenation?

• A. FiO2
• B. Respiratory rate
• C. PEEP (Correct Answer)
• D. Tidal volume

Exercise Physiology Explanation: ***PEEP*** - **Positive End-Expiratory Pressure (PEEP)** is crucial for maintaining optimal oxygenation because it prevents **alveolar collapse** at the end of expiration, thereby increasing the **functional residual capacity** and improving gas exchange. - By keeping alveoli open, PEEP increases the number of available alveoli for ventilation, preventing **atelectasis** and optimizing the **venous admixture** from non-ventilated lung units. *FiO2* - While **Fraction of Inspired Oxygen (FiO2)** is essential for providing sufficient oxygen, simply increasing FiO2 without proper alveolar recruitment and patency (often achieved with PEEP) can be less effective and potentially harmful due to **oxygen toxicity**. - High FiO2 can improve oxygenation in cases of **hypoxemia**, but it doesn't address underlying problems like **alveolar collapse** or **ventilation-perfusion mismatch** as directly as PEEP does. *Respiratory rate* - **Respiratory rate** primarily affects **carbon dioxide elimination** (PaCO2) and, to some extent, alveolar ventilation. - While an adequate respiratory rate is necessary for overall gas exchange, it is not the most direct or critical parameter for optimizing **oxygenation** compared to PEEP's role in maintaining alveolar patency. *Tidal volume* - **Tidal volume** also primarily affects **carbon dioxide elimination** and plays a role in overall minute ventilation. - Excessive tidal volume can lead to **ventilator-induced lung injury (VILI)**, while insufficient tidal volume can reduce minute ventilation, but it does not directly optimize oxygenation by preventing **alveolar collapse** in the same way PEEP does.

Exercise Physiology Indian Medical PG Question 6: Match the following drugs in Column A with their contraindications in Column B. | Column A | Column B | | :-- | :-- | | 1. Morphine | 1. QT prolongation | | 2. Amiodarone | 2. Thromboembolism | | 3. Vigabatrin | 3. Pregnancy | | 4. Estrogen preparations | 4. Head injury |

• A. A-1, B-3, C-2, D-4
• B. A-4, B-1, C-3, D-2 (Correct Answer)
• C. A-3, B-2, C-4, D-1
• D. A-2, B-4, C-1, D-3

Exercise Physiology Explanation: ***A-4, B-1, C-3, D-2*** - **Morphine** is contraindicated in **head injury** as it can increase intracranial pressure and mask neurological symptoms. - **Amiodarone** is contraindicated in patients with **QT prolongation** due to its risk of inducing more severe arrhythmias like Torsades de Pointes. - **Vigabatrin** is contraindicated during **pregnancy** due to its potential for teratogenicity and adverse effects on fetal development. - **Estrogen preparations** are contraindicated in patients with a history of **thromboembolism** due to their increased risk of blood clot formation. *A-1, B-3, C-2, D-4* - This option incorrectly matches **Morphine** with QT prolongation and **Estrogen preparations** with head injury, which are not their primary contraindications. - It also incorrectly links **Vigabatrin** with thromboembolism and **Amiodarone** with pregnancy. *A-3, B-2, C-4, D-1* - This choice incorrectly associates **Morphine** with pregnancy and **Vigabatrin** with head injury, which are not the most critical or direct contraindications. - It also misaligns **Amiodarone** with thromboembolism and **Estrogen preparations** with QT prolongation. *A-2, B-4, C-1, D-3* - This option incorrectly matches **Morphine** with thromboembolism and **Amiodarone** with head injury, which are not their most significant contraindications. - It also incorrectly links **Vigabatrin** with QT prolongation and **Estrogen preparations** with pregnancy.

Exercise Physiology Indian Medical PG Question 7: Mean bone density amongst 2 groups of 50 people each is compared, which would be the best test:

• A. McNemar test
• B. Chi-square test
• C. Student t-test (Correct Answer)
• D. Fisher exact test

Exercise Physiology Explanation: ***Student t-test*** - The **Student's t-test** is the appropriate statistical test for comparing the **means of two independent groups** when the data is continuous and normally distributed. - Bone density is a **continuous variable**, and the scenario involves comparing the mean bone density between two distinct groups. *Fisher exact test* - The **Fisher exact test** is used for analyzing **categorical data** in a 2×2 contingency table, especially when sample sizes are small. - It is not suitable for comparing continuous variables like bone density. *McNemar test* - **McNemar's test** is used to analyze paired nominal data, typically when comparing two related proportions from the same subjects before and after an intervention. - This scenario involves **independent groups**, not paired data. *Chi-square test* - The **chi-square test** is primarily used to compare **categorical variables** to see if there is a significant association between them. - It's not appropriate for comparing the means of continuous data like bone density.

Exercise Physiology Indian Medical PG Question 8: During a 100 m sprint which of the following is used by the muscle for meeting energy demands?

• A. Phosphofructokinase
• B. Phosphocreatine (Correct Answer)
• C. Glucose 1 - phosphate
• D. Creatine phosphokinase

Exercise Physiology Explanation: ***Phosphocreatine*** - **Phosphocreatine (PCr)** is the primary energy source for a **100m sprint** (lasting 10-20 seconds). - The **ATP-PC (phosphagen) system** provides **immediate energy** by rapidly regenerating **ATP** from ADP through the transfer of a high-energy phosphate group. - This system is crucial for **short bursts of maximal intensity exercise** where energy demand exceeds the capacity of glycolysis and oxidative phosphorylation to respond quickly enough. - Phosphocreatine stores can fuel maximum effort for approximately **10-15 seconds**, making it ideal for sprint activities. *Phosphofructokinase* - **Phosphofructokinase (PFK)** is a key regulatory enzyme in **glycolysis**, not an energy substrate. - While PFK-catalyzed glycolysis contributes ATP during intense exercise, it cannot provide energy as rapidly as the phosphocreatine system. - Glycolysis becomes more prominent after the first 10-15 seconds of maximal effort. *Glucose 1-phosphate* - **Glucose 1-phosphate** is an intermediate in **glycogenolysis** (breakdown of glycogen to glucose-6-phosphate). - It is part of the pathway leading to glucose availability for glycolysis, but is not a **direct, immediate energy source** for muscle contraction. - Unlike phosphocreatine, it cannot directly regenerate ATP. *Creatine phosphokinase* - **Creatine phosphokinase (CPK)**, also known as **creatine kinase (CK)**, is the **enzyme** that catalyzes the reversible transfer of phosphate from phosphocreatine to ADP. - It facilitates the energy transfer reaction but is **not an energy substrate** itself. - The enzyme enables the phosphocreatine system to function, but the actual energy comes from phosphocreatine.

Exercise Physiology Indian Medical PG Question 9: A hyperventilating patient has the following ABG values: pH=7.53, pCO2=20 mmHg, HCO3= 26 mEq/L. What is the most likely diagnosis?

• A. Metabolic alkalosis
• B. Metabolic acidosis
• C. Respiratory alkalosis (Correct Answer)
• D. Respiratory acidosis

Exercise Physiology Explanation: ***Respiratory alkalosis*** - The pH of 7.53 indicates **alkalemia**, and the low pCO2 (20 mmHg) is the primary driver, signifying **respiratory alkalosis** - A hyperventilating patient exhales more CO2, leading to a decrease in its partial pressure in the blood and a subsequent rise in pH - The HCO3 is within normal range (26 mEq/L), indicating **uncompensated respiratory alkalosis** *Metabolic alkalosis* - This would be characterized by a high pH and an elevated **HCO3**, but the HCO3 is within the normal range (26 mEq/L) - While it causes alkalemia, the primary disturbance here is respiratory, not metabolic *Metabolic acidosis* - This would present with a **low pH** and a low **HCO3**, which is contrary to the given ABG values - The patient's pH is elevated, indicating an alkalotic state, not acidotic *Respiratory acidosis* - This would be defined by a **low pH** and an elevated **pCO2**, which is the exact opposite of the provided ABG results - The patient's high pH and low pCO2 rule out respiratory acidosis

Exercise Physiology Indian Medical PG Question 10: The blood levels of hormones are elevated during exercise and sleep as shown. Which hormone would exhibit this diurnal pattern?

• A. Growth hormone (Correct Answer)
• B. Insulin
• C. Cortisol
• D. Thyroid hormones

Exercise Physiology Explanation: ***Growth hormone*** - **Growth hormone (GH)** secretion is known to increase significantly during both **strenuous exercise** and **sleep**, particularly during deep sleep stages. - The elevated levels during exercise promote **lipolysis** and **glucose production**, while during sleep, it facilitates **tissue repair** and **growth**. *Insulin* - **Insulin** levels typically **decrease during exercise** to promote the utilization of fat as fuel and increase during sleep in response to reduced metabolic demand and preparation for morning. - Its primary role is to regulate blood glucose, and its secretion is mainly stimulated by **high blood glucose** rather than exercise or sleep directly in this pattern. *Cortisol* - **Cortisol** secretion follows a **circadian rhythm**, peaking in the early morning and gradually decreasing throughout the day, reaching its lowest point at night. - While exercise can acutely increase cortisol, its **sleep-related pattern** is the opposite of what is shown, typically decreasing during early sleep. *Thyroid* - **Thyroid hormones (T3 and T4)** maintain a relatively **stable level** throughout the day and night, with minor diurnal fluctuations. - Their primary function is to regulate **metabolism** and they do not exhibit sharp, distinct peaks in response to exercise or sleep in the manner depicted.

Exercise Physiology Flashcard 1 of 9

Question: A person who consumes a _____ diet, has far more endurance for marathon races

Answer: high-carbohydrate

Exercise Physiology Flashcard 2 of 9

Question: Iso_____ exercise increases the after load of the heart

Answer: metric

Exercise Physiology Flashcard 3 of 9

Question: The lung diffusing capacity, DL, _____ during exercise due to increased surface area (A)

Answer: increases

Exercise Physiology Flashcard 4 of 9

Question: In an athelete, during exercise, the arterial pO2 will _____

Answer: remain same

Exercise Physiology Flashcard 5 of 9

Question: Blood flow _____ to muscles*, kidney, liver, and GIT during exercise

Answer: decreases

Exercise Physiology Flashcard 6 of 9

Question: Mc Ardle index is _____ rate

Answer: sweat

Extra Information: 

Exercise Physiology Flashcard 7 of 9

Question: f19bbc4344d44f18b5dc20ff1137c063-ao-

Answer: kcal energy requirements per day

Extra Information: 

Exercise Physiology Flashcard 8 of 9

Question: _____ circulation initially decreases but later increases during exercise

Answer: Cutaneous

Exercise Physiology Flashcard 9 of 9

Question: There is a sharp _____ in the diastolic blood pressure in isometric exercise.

Answer: rise