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TSAC-F practice questions

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Question 1Scientific Foundations

Which characteristic best describes Type I (slow-twitch) muscle fibers?

  1. Large motor unit size
  2. High glycolytic capacity
  3. High oxidative capacity Correct answer.
  4. Rapid force production

Explanation

Type I fibers are rich in mitochondria and capillaries and rely mainly on oxidative metabolism, which gives them a high resistance to fatigue. Fast-twitch fibers possess the greater glycolytic capacity and force-generating potential.

Question 2Scientific Foundations

Approximately how long can the phosphagen (ATP-PC) system supply energy at maximal intensity?

  1. 8 to 12 seconds Correct answer.
  2. 2 to 5 seconds
  3. 3 to 5 minutes
  4. 60 to 90 seconds

Explanation

Stored ATP and phosphocreatine can fuel all-out effort for roughly 8 to 12 seconds before depletion limits power output. Beyond this window, anaerobic glycolysis becomes the dominant contributor.

Question 3Scientific Foundations

At rest, which fuel source supplies the largest proportion of ATP production?

  1. Alcohol
  2. Muscle glycogen
  3. Fat Correct answer.
  4. Protein

Explanation

In the resting state, fatty acid oxidation provides the majority of ATP for skeletal muscle and other tissues. Carbohydrate use rises sharply as exercise intensity increases.

Question 4Scientific Foundations

Which term describes a muscle that opposes the action of the prime mover?

  1. Antagonist Correct answer.
  2. Stabilizer
  3. Agonist
  4. Synergist

Explanation

The antagonist produces the opposite action at a joint and lengthens or relaxes as the agonist shortens. This pairing allows controlled, coordinated movement.

Question 5Scientific Foundations

In the sliding filament theory, which ion binds to troponin to expose myosin-binding sites on actin?

  1. Sodium
  2. Potassium
  3. Calcium Correct answer.
  4. Magnesium

Explanation

Calcium released from the sarcoplasmic reticulum binds troponin, shifting tropomyosin and uncovering the actin binding sites. Cross-bridge formation can then proceed.

Question 6Scientific Foundations

Which resting heart rate range is most typical for a healthy adult?

  1. 30 to 40 bpm
  2. 60 to 80 bpm Correct answer.
  3. 100 to 120 bpm
  4. 130 to 150 bpm

Explanation

Normal resting heart rate for adults falls near 60 to 80 beats per minute, though trained individuals may sit at the lower end. Values well outside this range warrant follow-up.

Question 7Scientific Foundations

Which plane divides the body into left and right portions?

  1. Transverse plane
  2. Oblique plane
  3. Sagittal plane Correct answer.
  4. Frontal plane

Explanation

The sagittal plane runs vertically front to back and separates the body into left and right sections. Movements such as flexion and extension of the knee occur largely within it.

Question 8Scientific Foundations

Delayed-onset muscle soreness typically peaks how long after an unaccustomed exercise bout?

  1. 24 to 72 hours after exercise Correct answer.
  2. Immediately after exercise
  3. 2 to 4 hours after exercise
  4. 6 to 8 hours after exercise

Explanation

Soreness from eccentric or novel exercise usually appears within a day and peaks between 24 and 72 hours. It reflects an inflammatory response to mechanical damage rather than acute lactate accumulation.

Question 9Scientific Foundations

During glycolysis, what is the net ATP yield from one molecule of glucose?

  1. 6 ATP
  2. 2 ATP Correct answer.
  3. 38 ATP
  4. 4 ATP

Explanation

Glycolysis produces four ATP but consumes two during its investment phase, leaving a net yield of two ATP plus two pyruvate molecules.

Question 10Scientific Foundations

Excess post-exercise oxygen consumption (EPOC) is best described as:

  1. Cooling of the body during exercise
  2. Reduction of heart rate during exercise
  3. Elevated glycogen breakdown during exercise
  4. Restoration of homeostasis after exercise Correct answer.

Explanation

EPOC reflects the elevated oxygen uptake after exercise that supports replenishment of phosphocreatine, lactate clearance, and normalization of hormones and temperature. It is a recovery process rather than a within-bout phenomenon.

Question 11Scientific Foundations

According to the force-velocity relationship for concentric muscle actions, as shortening velocity increases, force production:

  1. Increases linearly
  2. Remains unchanged
  3. Decreases Correct answer.
  4. Increases then plateaus

Explanation

Force and shortening velocity are inversely related: the faster a muscle shortens, the fewer cross-bridges are attached at any instant and the lower the force. Maximal force occurs at zero velocity.

Question 12Scientific Foundations

Muscle spindles primarily detect changes in:

  1. Local blood flow
  2. Muscle tension
  3. Muscle length and rate of stretch Correct answer.
  4. Joint position alone

Explanation

Spindles lie parallel to muscle fibers and signal both the magnitude and speed of stretch, driving the stretch reflex. Tension sensing is handled by a different receptor.

Question 13Scientific Foundations

Which receptor signals tension and triggers reflexive relaxation when force becomes excessive?

  1. Ruffini ending
  2. Muscle spindle
  3. Pacinian corpuscle
  4. Golgi tendon organ Correct answer.

Explanation

The Golgi tendon organ sits in series with the tendon and monitors tension, producing autogenic inhibition that reduces force output when loads are excessive. This protects the muscle-tendon unit.

Question 14Scientific Foundations

If stroke volume is 80 mL and heart rate is 150 beats per minute, cardiac output is approximately:

  1. 1.2 L/min
  2. 120 L/min
  3. 18.75 L/min
  4. 12 L/min Correct answer.

Explanation

Cardiac output equals stroke volume multiplied by heart rate, so 80 mL times 150 beats per minute gives 12,000 mL, or 12 L/min.

Question 15Scientific Foundations

Blood lactate threshold is best defined as:

  1. The maximal lactate concentration attainable during sprinting
  2. The intensity where lactate accumulates faster than it is cleared Correct answer.
  3. The intensity at which lactate first appears in blood
  4. The point at which lactate production ceases

Explanation

Lactate is always present at low concentrations; the threshold marks the intensity at which appearance in the blood outpaces clearance, causing a sustained rise. It is a key marker of endurance performance.

Question 16Scientific Foundations

For tactical athletes performing strength training, general daily protein intake recommendations are approximately:

  1. 2.5 to 3.0 g/kg/day
  2. 0.8 to 1.0 g/kg/day
  3. 1.4 to 2.0 g/kg/day Correct answer.
  4. 0.4 to 0.6 g/kg/day

Explanation

Strength-trained individuals generally need roughly 1.4 to 2.0 grams of protein per kilogram of body mass daily to support repair and adaptation. This exceeds the requirement for sedentary adults.

Question 17Scientific Foundations

During the first 4 to 6 weeks of a resistance training program, most strength gains are primarily attributable to:

  1. Muscle fiber hyperplasia
  2. Increased muscle cross-sectional area
  3. Increased tendon stiffness
  4. Neural adaptations Correct answer.

Explanation

Early strength gains outpace measurable muscle growth and are driven largely by improved motor unit recruitment, rate coding, and coordination. Hypertrophy contributes more once training continues beyond this initial phase.

Question 18Scientific Foundations

Which response is most closely associated with an active warm-up before a tactical fitness test?

  1. Decreased nerve conduction velocity
  2. Reduced muscle compliance
  3. Reduced blood flow to working muscles
  4. Increased muscle temperature Correct answer.

Explanation

An active warm-up raises muscle temperature, which enhances enzyme activity, cross-bridge cycling rate, and nerve conduction velocity. These changes support faster and more forceful contractions.

Question 19Scientific Foundations

Prolonged static stretching performed immediately before a maximal power test is most likely to:

  1. Increase peak power output
  2. Increase muscle spindle sensitivity
  3. Reduce force and power output Correct answer.
  4. Improve jump height

Explanation

Extended static stretching before power activity can transiently reduce musculotendinous stiffness and neural drive, lowering force and power. Dynamic preparation is preferred before explosive testing.

Question 20Scientific Foundations

Which physiological change occurs during a Valsalva maneuver?

  1. Increased intrathoracic pressure Correct answer.
  2. Decreased heart rate throughout the strain
  3. Reduced systolic blood pressure
  4. Decreased intrathoracic pressure

Explanation

Breath holding against a closed glottis raises intrathoracic pressure, which stiffens the trunk and temporarily elevates blood pressure. The maneuver should be used cautiously with tactical athletes who have cardiovascular risk.

Question 21Scientific Foundations

Peak active force production in a sarcomere occurs when:

  1. The sarcomere is maximally shortened
  2. Optimal actin-myosin overlap is present Correct answer.
  3. Actin filaments overlap each other at the Z-lines
  4. The sarcomere is fully stretched

Explanation

Force is greatest at the length where the maximum number of myosin heads can bind actin. Both overstretching and over-shortening reduce the number of available cross-bridges.

Question 22Scientific Foundations

According to the size principle, motor units are recruited:

  1. Randomly, independent of force demand
  2. From largest to smallest with increasing force
  3. Simultaneously at all force levels
  4. From smallest to largest with increasing force Correct answer.

Explanation

Motor units are recruited in ascending order of size, so small, fatigue-resistant units fire first and larger, more powerful units are added as demand rises. This pattern preserves efficiency and fine control.

Question 23Scientific Foundations

Which event is required for myosin to detach from actin during the cross-bridge cycle?

  1. Release of inorganic phosphate
  2. Hydrolysis of ATP to ADP and phosphate
  3. Calcium binding to troponin
  4. ATP binding to the myosin head Correct answer.

Explanation

Binding of a new ATP molecule to the myosin head reduces its affinity for actin and allows detachment. Subsequent hydrolysis of that ATP re-cocks the head for the next power stroke.

Question 24Scientific Foundations

During a maximal 30-second sprint, the predominant energy system is:

  1. Oxidative phosphorylation
  2. Anaerobic glycolysis Correct answer.
  3. The ATP-PC system alone
  4. The ATP-PC system and glycolysis in equal share

Explanation

By roughly 10 seconds, phosphocreatine stores are largely depleted and anaerobic glycolysis supplies most of the ATP for the remainder of a 30-second maximal effort. Oxidative contribution remains small at this intensity.

Question 25Scientific Foundations

Which adaptation is most consistently observed in skeletal muscle after prolonged endurance training?

  1. Increased fiber cross-sectional area
  2. Increased capillary density Correct answer.
  3. Increased glycolytic enzyme activity
  4. Increased Type IIx fiber proportion

Explanation

Endurance training promotes angiogenesis around trained fibers, improving oxygen and substrate delivery. It also raises mitochondrial and oxidative enzyme content while shifting IIx fibers toward IIa.

Question 26Scientific Foundations

Which neurotransmitter is released at the neuromuscular junction to initiate skeletal muscle contraction?

  1. Dopamine
  2. Norepinephrine
  3. Gamma-aminobutyric acid
  4. Acetylcholine Correct answer.

Explanation

Motor neurons release acetylcholine from the axon terminal into the synaptic cleft. It binds nicotinic receptors on the sarcolemma, causing depolarization that spreads into the T-tubules and triggers calcium release from the sarcoplasmic reticulum.

Question 27Scientific Foundations

The phosphagen (ATP-PC) system is best described by which statement?

  1. Powers brief maximal efforts of about 10 seconds Correct answer.
  2. Becomes the dominant ATP source after 2 minutes of exercise
  3. Provides the majority of ATP during a 10-minute steady-state run
  4. Requires oxygen to resynthesize ATP from creatine phosphate

Explanation

Creatine kinase rapidly resynthesizes ATP from phosphocreatine without oxygen, but the intramuscular store is small. It dominates only during very short, very intense efforts, generally up to about 10 seconds.

Question 28Scientific Foundations

What is the primary metabolic action of insulin?

  1. Promotes glucose uptake by muscle and fat Correct answer.
  2. Increases lipolysis in adipose tissue
  3. Increases sodium reabsorption in the kidney
  4. Stimulates glycogenolysis in the liver during fasting

Explanation

Insulin binds receptors on skeletal muscle and adipose tissue and causes GLUT4 transporters to move to the cell membrane, increasing glucose entry. It also promotes glycogen and fat storage, functioning as the body's main anabolic storage hormone.

Question 29Scientific Foundations

Creatine monohydrate supplementation improves high-intensity performance primarily by doing which of the following?

  1. Enhancing fat oxidation during steady-state work
  2. Raising stored phosphocreatine for ATP resynthesis Correct answer.
  3. Improving oxygen delivery to working muscle
  4. Increasing muscle protein synthesis after heavy resistance training

Explanation

Loading creatine increases intramuscular phosphocreatine content, extending the capacity of the ATP-PC system to regenerate ATP during short, intense efforts. The benefit is therefore greatest in repeated sprints and heavy resistance work.

Question 30Scientific Foundations

Which set of characteristics best describes Type I skeletal muscle fibers?

  1. High mitochondrial density and fatigue resistance Correct answer.
  2. High glycolytic enzyme activity
  3. Large cross-sectional area and rapid contraction
  4. Low myoglobin content and pale appearance

Explanation

Type I fibers are oxidative, richly supplied with mitochondria and capillaries, and possess high myoglobin content. These traits give them a slow contraction speed but strong resistance to fatigue, making them suited to postural and endurance work.

Question 31Scientific Foundations

A limitation of body mass index when screening tactical athletes is best described by which statement?

  1. It is only valid for adults over 65 years of age
  2. It does not distinguish between fat mass and lean mass Correct answer.
  3. It requires underwater weighing equipment
  4. It cannot be calculated from height and weight

Explanation

BMI uses only height and weight, so a heavily muscled athlete can be classified as overweight or obese despite low body fat. Body composition methods such as skinfolds or bioelectrical impedance are needed to separate fat from lean tissue.

Question 32Scientific Foundations

Progressive overload is best defined as which of the following?

  1. Alternating hard and easy training days within a week
  2. Systematically increasing the training stimulus as the body adapts Correct answer.
  3. Performing the same workout at the same load indefinitely
  4. Training to momentary muscular failure on every set

Explanation

Progressive overload means the training stress is raised over time, through load, volume, density, or complexity, so that adaptation continues. Without a gradually increasing stimulus, gains plateau once the body has adapted to the current demand.

Question 33Scientific Foundations

Sarcopenia is best described as which of the following?

  1. Age-related loss of skeletal muscle mass and strength Correct answer.
  2. Excessive muscle hypertrophy from overtraining
  3. Sudden muscle weakness caused by nerve injury
  4. Loss of joint range of motion with aging

Explanation

Sarcopenia is the gradual decline in muscle mass, quality, and strength that accompanies aging, beginning in midlife and accelerating later. Resistance training and adequate protein intake are the primary countermeasures.

Question 34Scientific Foundations

Within physiological limits, an increase in end-diastolic volume raises stroke volume because of which mechanism?

  1. Heart rate decreases proportionally to the volume increase
  2. Greater myocardial stretch increases contraction force Correct answer.
  3. Sympathetic outflow is inhibited by atrial distension
  4. Afterload falls automatically as preload rises

Explanation

This is the Frank-Starling relationship: greater filling stretches cardiac myocytes, which increases calcium sensitivity and actin-myosin interaction, producing a stronger contraction. The result is a larger stroke volume from the same neural drive.

Question 35Scientific Foundations

A force of 200 N is applied 0.25 m from a joint's axis of rotation. What torque is produced?

  1. 500 N·m
  2. 50 N·m Correct answer.
  3. 800 N·m
  4. 8 N·m

Explanation

Torque equals force multiplied by the perpendicular moment arm, so 200 N × 0.25 m = 50 N·m. Moment arm length has a large influence because the relationship is linear with distance.

Question 36Scientific Foundations

A tactical athlete has a blood pressure of 128/76 mmHg. The estimated mean arterial pressure is closest to which value?

  1. 128 mmHg
  2. 102 mmHg
  3. 76 mmHg
  4. 93 mmHg Correct answer.

Explanation

Mean arterial pressure is estimated as diastolic pressure plus one-third of the pulse pressure. Here the pulse pressure is 52 mmHg, so MAP ≈ 76 + 17 = 93 mmHg.

Question 37Scientific Foundations

After 7 to 14 days of training in a hot environment, the most characteristic adaptation is which of the following?

  1. Higher sweat rate with lower sodium concentration Correct answer.
  2. Reduced plasma volume
  3. A higher core temperature threshold for the onset of sweating
  4. Decreased cutaneous blood flow during exercise in the heat

Explanation

Heat acclimation expands plasma volume, allows sweating to begin earlier and at a higher rate, and reduces sodium lost per liter of sweat. Together these improve heat dissipation and lower cardiovascular strain.

Question 38Scientific Foundations

Which change is most typical after 2 to 4 weeks of complete training cessation in a previously trained individual?

  1. Increase in capillary density
  2. Reduction in stroke volume and plasma volume Correct answer.
  3. A continued rise in mitochondrial enzyme activity
  4. Rise in maximal oxygen uptake

Explanation

Detraining rapidly reverses cardiovascular adaptations, with plasma volume and stroke volume decreasing within the first few weeks. Mitochondrial enzyme activity and capillary density also decline, lowering aerobic capacity.

Question 39Scientific Foundations

Compared with concentric actions at the same load, eccentric muscle actions can do which of the following?

  1. Produce greater maximal force Correct answer.
  2. Require greater motor unit recruitment at the same force output
  3. Produce force only while the muscle shortens
  4. Generate less force at any given velocity

Explanation

Eccentric actions can generate greater force than concentric actions and require fewer active motor units for a given absolute load. This is why athletes can lower loads heavier than they can lift.

Question 40Scientific Foundations

The stretch-shortening cycle enhances power output primarily through which mechanism?

  1. Increased rate of ATP hydrolysis in the ATP-PC system
  2. Voluntary inhibition of the stretch reflex
  3. Storage and release of elastic energy plus the stretch reflex Correct answer.
  4. Greater reliance on oxidative metabolism

Explanation

A rapid countermovement stores elastic energy in tendons and series elastic elements and triggers the stretch reflex. Releasing that energy in the subsequent concentric phase adds to voluntary force production.

Question 41Scientific Foundations

Caffeine's ergogenic effect on endurance and strength performance is primarily attributed to which action?

  1. Antagonism of adenosine receptors in the central nervous system Correct answer.
  2. Direct stimulation of beta-2 receptors on the heart
  3. Increased phosphocreatine synthesis in the liver
  4. Blockade of acetylcholine release at the neuromuscular junction

Explanation

Caffeine blocks adenosine receptors, reducing perceived exertion and fatigue and increasing neural drive. This central mechanism explains much of the performance benefit across aerobic and strength tasks.

Question 42Scientific Foundations

According to the Fick equation, oxygen consumption is calculated as which product?

  1. Minute ventilation multiplied by the fraction of oxygen in expired air
  2. Stroke volume divided by arterial oxygen content
  3. Heart rate multiplied by total peripheral resistance
  4. Cardiac output multiplied by the a-vO2 difference Correct answer.

Explanation

The Fick equation states that VO2 equals cardiac output times the arteriovenous oxygen difference. This shows that aerobic capacity depends on both central delivery and peripheral extraction of oxygen.

Question 43Scientific Foundations

During prolonged exercise in the heat, performance typically begins to decline once body mass loss from sweating exceeds approximately what percentage?

  1. 1%
  2. 8%
  3. 0.5%
  4. 2% Correct answer.

Explanation

A body mass deficit of about 2% is the commonly cited threshold at which cardiovascular strain rises and endurance performance deteriorates. Larger deficits progressively worsen thermoregulation and cognitive function.

Question 44Scientific Foundations

Chronically elevated cortisol associated with overtraining most likely contributes to which outcome?

  1. Enhanced glycogen storage
  2. Muscle protein breakdown and impaired recovery Correct answer.
  3. Reduced gluconeogenesis
  4. Increased muscle protein synthesis

Explanation

Cortisol is a catabolic hormone that promotes proteolysis and gluconeogenesis while suppressing immune and reproductive function. When chronically elevated with inadequate recovery, it favors muscle breakdown and slows adaptation.

Question 45Scientific Foundations

Wolff's law describes bone adapting to mechanical loading in which way?

  1. Resorbing bone at sites of high load
  2. Shifting from cortical to cancellous structure under load
  3. Reducing mineral density in loaded limbs
  4. Depositing new bone along lines of stress Correct answer.

Explanation

Bone remodels in response to the loads placed on it, adding mineral and matrix where stress is greatest. This principle underlies the osteogenic benefit of load-bearing and resistance training.

Question 46Scientific Foundations

A respiratory exchange ratio of 1.00 during steady-state exercise most likely indicates which of the following?

  1. Exclusive protein oxidation
  2. A measurement error, because RER cannot exceed 0.85 during exercise
  3. Exclusive fat oxidation
  4. Exclusive carbohydrate oxidation with normal ventilation Correct answer.

Explanation

RER near 1.00 reflects carbohydrate as the nearly exclusive fuel, since carbohydrate oxidation yields one CO2 per O2 consumed. Values above about 1.10 usually suggest hyperventilation rather than true fuel use.

Question 47Scientific Foundations

Which statement best describes lactate production and use during intense exercise?

  1. It accumulates because muscle cannot clear it at all
  2. It is produced continuously and cleared as fuel by other fibers Correct answer.
  3. It directly causes muscle acidosis by releasing hydrogen ions from ATP
  4. It is produced only when oxygen is entirely absent

Explanation

Lactate is formed continuously when glycolytic flux outpaces pyruvate oxidation, and it is shuttled to other fibers, the heart, and the liver for oxidation or gluconeogenesis. Accumulation reflects production exceeding clearance rather than a total inability to clear it.

Question 48Scientific Foundations

At an altitude of 2,500 m, maximal oxygen uptake falls primarily because of which factor?

  1. Barometric pressure is the same but oxygen falls
  2. Hemoglobin concentration drops immediately
  3. Minute ventilation is reduced below sea-level values
  4. The partial pressure of oxygen in inspired air is lower Correct answer.

Explanation

Although the fraction of oxygen in air remains about 20.9%, the lower barometric pressure reduces the partial pressure of inspired oxygen. This lowers alveolar and arterial oxygen pressure, reducing the oxygen gradient driving uptake.

Question 49Scientific Foundations

A single bout of unaccustomed eccentric exercise reduces muscle damage on a subsequent identical bout. What is this phenomenon called?

  1. The cross-education effect
  2. The size principle
  3. The repeated bout effect Correct answer.
  4. Post-activation potentiation

Explanation

The repeated bout effect is the protective adaptation whereby prior eccentric loading attenuates damage, soreness, and strength loss on later exposures. Neural, mechanical, and cellular adaptations all contribute.

Question 50Scientific Foundations

During a concentric contraction, which change occurs within a sarcomere?

  1. The A band shortens
  2. Actin filaments shorten
  3. The I band and H zone narrow Correct answer.
  4. The distance between Z lines increases

Explanation

Thin filaments slide past thick filaments toward the sarcomere center, so the I band and H zone narrow while the A band stays constant in length. The Z lines move closer together as the sarcomere shortens.