Exercise Physiology Practice Questions

Q: In a 40-year-old person, what is the estimated maximum heart rate?

180 bpm. **Explanation:** The maximum heart rate (MHR) is the highest number of beats per minute a person's heart can safely reach during maximum physical exertion. In clinical physiology and sports medicine, the most widely accepted and high-yield formula for estimating MHR is the **Fox-Haskell formula**: **Maximum Heart Rate (MHR) = 220 – Age (in years)** For a 40-year-old individual: $MHR = 220 - 40 = 180 \text{ bpm}$ **Analysis of Options:** * **Option B (180 bpm):** Correct. This aligns perfectly with the standard physiological calculation ($220 - 40$). * **Option A (160 bpm):** Incorrect. This would be the MHR for a 60-year-old ($220 - 60$). * **Option C (200 bpm):** Incorrect. This would be the MHR for a 20-year-old ($220 - 20$). * **Option D (220 bpm):** Incorrect. This represents the constant used in the formula, or the theoretical MHR of a newborn. **High-Yield Facts for NEET-PG:** 1. **Age-Dependency:** MHR decreases linearly with age due to a decrease in the intrinsic heart rate and a reduction in the sensitivity of beta-adrenergic receptors in the SA node. 2. **Target Heart Rate (THR):** For moderate-intensity exercise, the target is usually 50–70% of the MHR. For vigorous intensity, it is 70–85%. 3. **Tanaka Formula:** A more precise (though less commonly tested) formula is $208 - (0.7 \times \text{Age})$. 4. **Clinical Correlation:** MHR is a critical parameter during **Treadmill Testing (TMT)**. A test is often considered "diagnostic" if the patient reaches 85% of their age-predicted MHR.

Q: Which of the following is NOT a physiological change during severe exercise?

Decreased paO2. In exercise physiology, maintaining arterial blood gas homeostasis is a key regulatory mechanism. Here is the breakdown of the physiological changes: **Why "Decreased paO2" is the Correct Answer:** In a healthy individual, even during severe exercise, **arterial oxygen tension (paO2) does not decrease.** The respiratory system is highly efficient; the increase in alveolar ventilation matches or even exceeds the increase in oxygen consumption ($VO_2$). While the *venous* $O_2$ content drops significantly as tissues extract more oxygen, the *arterial* $PO_2$ remains normal (~100 mmHg) or may slightly increase due to hyperventilation. **Analysis of Incorrect Options:** * **Hyperventilation (A):** At the onset of exercise, there is an immediate "neurogenic" increase in ventilation (driven by the cerebral cortex and joint proprioceptors) followed by humoral adjustments. * **Hyperkalemia (B):** During strenuous exercise, repeated muscle depolarization leads to an efflux of Potassium ($K^+$) from the skeletal muscle cells into the extracellular fluid. This transient hyperkalemia is a classic finding in severe exercise. * **Decreased paCO2 (D):** During severe (anaerobic) exercise, lactic acid accumulates. The resulting metabolic acidosis stimulates peripheral chemoreceptors, leading to compensatory hyperventilation. This "blows off" $CO_2$, causing the arterial $PCO_2$ to drop below normal resting levels. **High-Yield Clinical Pearls for NEET-PG:** * **Diffusion Capacity:** $O_2$ diffusion capacity increases up to 3-fold during exercise due to increased pulmonary capillary perfusion and recruitment. * **Oxy-hemoglobin Curve:** Exercise shifts the curve to the **Right** (due to increased $H^+$, $CO_2$, Temperature, and 2,3-DPG), facilitating $O_2$ unloading at tissues. * **Anaerobic Threshold:** The point where lactic acid starts accumulating and $V_E$ (ventilation) increases disproportionately to $VO_2$.

Q: Soreness and pain in muscles after vigorous exercise is due to -

Lactic acidosis. **Explanation:** **Why Lactic Acidosis is the Correct Answer:** During vigorous or strenuous exercise, the oxygen demand of the skeletal muscles exceeds the supply provided by the cardiovascular system. To meet the energy requirements, muscles switch from aerobic metabolism to **anaerobic glycolysis**. In this pathway, pyruvate is converted into **lactic acid** by the enzyme lactate dehydrogenase (LDH). The accumulation of lactic acid leads to a drop in local pH (lactic acidosis), which irritates sensory nerve endings (nociceptors), resulting in the characteristic sensation of muscle soreness and burning pain during or immediately after exercise. **Analysis of Incorrect Options:** * **A. Hyperkalemia:** While potassium shifts from the intracellular to the extracellular space during muscle contraction, it primarily contributes to muscle fatigue rather than acute soreness. * **C. Hyperthermia:** Vigorous exercise increases core body temperature due to metabolic heat production, but this causes systemic exhaustion or heat cramps rather than localized muscle soreness. * **D. Hyponatremia:** Low sodium levels (often due to excessive water intake during endurance sports) lead to confusion, seizures, or generalized muscle cramps, but not the specific soreness associated with anaerobic exertion. **High-Yield Facts for NEET-PG:** * **Cori Cycle:** Lactic acid produced in the muscles is transported to the liver, where it is converted back into glucose (gluconeogenesis). * **Oxygen Debt:** The extra oxygen required after exercise to metabolize accumulated lactate and restore ATP/creatine phosphate stores is known as the "Oxygen Debt" or EPOC (Excess Post-exercise Oxygen Consumption). * **DOMS (Delayed Onset Muscle Soreness):** While acute pain is due to lactic acid, soreness occurring 24–48 hours later is primarily due to microscopic tears in muscle fibers (microtrauma) and subsequent inflammation, not lactic acid.

Q: Which of the following does not increase during isotonic exercise?

Total peripheral resistance. **Explanation:** In **isotonic (dynamic) exercise**, such as running or swimming, the body undergoes significant cardiovascular adjustments to meet the increased oxygen demand of skeletal muscles. **Why Total Peripheral Resistance (TPR) decreases:** The hallmark of isotonic exercise is **marked vasodilation** in the active skeletal muscle beds, mediated by local metabolic factors (e.g., increased $K^+$, $H^+$, adenosine, and $CO_2$). Although there is sympathetic vasoconstriction in non-essential organs (like the kidneys and GI tract), the massive vasodilation in the large muscle mass significantly outweighs this, leading to a **net decrease in Total Peripheral Resistance.** **Why the other options are incorrect:** * **Heart Rate (C):** Increases significantly due to sympathetic stimulation and withdrawal of parasympathetic (vagal) tone to increase cardiac output. * **Stroke Volume (D):** Increases due to increased venous return (skeletal muscle pump) and increased myocardial contractility (Frank-Starling mechanism and sympathetic effect). * **Respiration Rate (A):** Increases (hyperpnea) to enhance gas exchange and meet the metabolic demands of the tissues, driven by central command and peripheral chemoreceptors. **High-Yield Clinical Pearls for NEET-PG:** * **Isotonic vs. Isometric:** In **Isotonic** exercise, TPR decreases and Pulse Pressure increases. In **Isometric (static)** exercise (e.g., weightlifting), TPR may actually increase or stay the same due to mechanical compression of blood vessels, leading to a sharper rise in Mean Arterial Pressure. * **Systolic BP** increases in isotonic exercise, while **Diastolic BP** usually remains constant or decreases slightly (due to decreased TPR). * **Cardiac Output ($CO = HR \times SV$):** Both components increase, leading to a 4–6 fold increase in CO in elite athletes.

Q: Investigators observe that sending children outside to play instead of letting them sit for hours in front of the television can have long-term health benefits. Which of the following tissues is most likely to be in better condition by middle age from this lifestyle change?

Bone fractures. **Explanation:** The correct answer is **Bone fractures**. This question highlights the physiological principle of **Peak Bone Mass (PBM)** and the impact of weight-bearing exercise on skeletal health. **Why Bone Fractures is correct:** During childhood and adolescence, bone tissue is highly responsive to mechanical loading. Physical activity (like running and playing) stimulates osteoblast activity via mechanotransduction, increasing bone mineral density (BMD). Approximately 90% of peak bone mass is acquired by age 18 in girls and age 20 in boys. A sedentary lifestyle (e.g., excessive TV time) during these formative years leads to lower PBM. By middle age, as natural age-related bone resorption begins, individuals with a higher "skeletal bank account" from an active childhood are significantly less likely to suffer from osteoporosis and fragility fractures. **Why the other options are incorrect:** * **Ocular cataracts:** These are primarily related to aging, UV exposure, and metabolic factors (like diabetes), rather than childhood physical activity. * **Urinary tract calculi:** While hydration and diet play roles, childhood exercise is not a primary preventative factor for kidney stones in middle age. * **Pulmonary emphysema:** This is a chronic obstructive pulmonary disease (COPD) primarily caused by smoking or alpha-1 antitrypsin deficiency, not a lack of childhood exercise. **NEET-PG Clinical Pearls:** * **Wolff’s Law:** Bone grows or remodels in response to the forces or demands placed upon it. * **Mechanostat Theory:** There is a threshold of mechanical strain required to trigger bone formation; sedentary behavior fails to reach this threshold. * **High-Yield Fact:** Weight-bearing exercises (jumping, running) are superior to non-weight-bearing exercises (swimming) for increasing BMD.

Question 1

In a 40-year-old person, what is the estimated maximum heart rate?

Accepted Answer

180 bpm

Answer

160 bpm

Answer

200 bpm

Answer

220 bpm

Question 2

Which of the following is TRUE regarding physiological changes in the brain during moderate exercise?

Accepted Answer

Blood flow remains unaltered

Answer

Blood flow is decreased

Answer

Blood flow is increased

Answer

Blood flow initially increases and then decreases

Question 3

Which of the following maximally increases the aerobic capacity?

Accepted Answer

Regular 3 minute exercise

Answer

Spurts of exercise

Answer

Prolonged exercise

Answer

Strenuous exercise

Question 4

All of the following are TRUE about isometric exercises, EXCEPT:

Accepted Answer

Useful in ventricular arrhythmia

Answer

S3, S4 is accentuated

Answer

Increases systemic vascular resistance

Answer

Diastolic murmur of Mitral stenosis becomes louder

Question 5

Which of the following is NOT a physiological change during severe exercise?

Accepted Answer

Decreased paO2

Answer

Hyperventilation in the beginning

Answer

Hyperkalemia

Answer

Decreased paCO2

Question 6

During vigorous strenuous exercise, which of the following amino acids is liberated from the skeletal muscles in the maximum amount into circulation?

Accepted Answer

Alanine

Answer

Glutamate

Answer

Glutamine

Answer

Branched chain amino acids

Question 7

Soreness and pain in muscles after vigorous exercise is due to -

Accepted Answer

Lactic acidosis

Answer

Hyperkalemia

Answer

Hyperthermia

Answer

Hyponatremia

Question 8

Which of the following does not increase during isotonic exercise?

Accepted Answer

Total peripheral resistance

Answer

Respiration rate

Answer

Heart rate

Answer

Stroke volume

Question 9

Which of the following is NOT a true change in the circulating blood flow of an exercising muscle?

Accepted Answer

Peripheral resistance increases.

Answer

Complete flow stops on maximal tension reaching 70% of maximum.

Answer

Blood supply increases by approximately 30 times between contractions.

Answer

Dilation of arterioles and pre-capillary sphincters occurs.

Question 10

Investigators observe that sending children outside to play instead of letting them sit for hours in front of the television can have long-term health benefits. Which of the following tissues is most likely to be in better condition by middle age from this lifestyle change?

Accepted Answer

Bone fractures

Answer

Ocular cataracts

Answer

Urinary tract calculi

Answer

Pulmonary emphysema

Exercise Physiology — MCQs

Exercise Physiology — MCQs

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