CSCS exercise sciences, the largest domain

An athlete performs a heavy split squat with good balance but loses balance repeatedly during a bodyweight single-leg squat. Which factor BEST explains the difference in stability?

1. Smaller base of support
   On one foot, the base of support shrinks to a single footprint, so the athlete's line of gravity leaves it far more easily than in a split stance.
2. Higher center of mass
   Holding a heavy barbell during the split squat raises the system's center of mass, so a higher center of mass cannot explain why the bodyweight version is less stable.
3. Lighter external load
   A lighter load does not destabilize an athlete; the difference comes from the size of the base, not from how much weight is held.

During 60 minutes of cycling at a constant power output in a hot environment, an athlete's heart rate rises from 145 to 162 bpm while cardiac output stays about the same. Which change BEST explains the rise in heart rate?

1. Rising blood lactate
   At a constant, steady power output, lactate stays fairly stable and is not what drives a slow upward creep in heart rate.
2. Expanding plasma volume
   Plasma volume falls during prolonged sweating in the heat; an expanding plasma volume would support stroke volume and lower heart rate.
3. Falling stroke volume
   In the heat, sweating and blood sent to the skin lower venous return and stroke volume, so heart rate climbs to hold cardiac output steady (cardiovascular drift).

During a maximal isometric pull, an athlete's force suddenly drops as tendon tension becomes very high. Which receptor is MOST responsible for this protective inhibition of the working muscle?

1. Golgi tendon organ
   The Golgi tendon organ senses high tendon tension and inhibits the working muscle (autogenic inhibition), which matches a sudden drop in force.
2. Muscle spindle
   The muscle spindle detects stretch and triggers a reflex contraction, so it would add force rather than shut it off.
3. Pacinian corpuscle
   Pacinian corpuscles sense pressure and vibration in the skin and joints; they do not regulate muscle force through tendon tension.

After 12 weeks of heavy resistance training, a muscle biopsy of a previously untrained athlete is MOST likely to show which fiber-type change?

1. Type IIx to type IIa shift
   Heavy resistance training moves type IIx fibers toward the IIa profile, which is the typical biopsy finding after a few months of training.
2. Type IIa to type IIx shift
   A shift from IIa toward IIx is the direction seen with detraining, not with heavy training.
3. Type I to type II conversion
   Type I fibers do not convert into type II fibers with resistance training, so this conversion is not an expected result.

During the concentric phase of a lift, an athlete raises a 100-kg (220-lb) barbell 0.8 m in 0.5 seconds. Using g = 9.81 m·s⁻², what is the athlete's average power output?

1. ≈160 W
   About 160 W uses mass in place of force, leaving out gravity, so the result is roughly ten times too small.
2. ≈1,960 W
   About 1,960 W comes from dividing the bar's weight by the time and leaving out the 0.8-m distance.
3. ≈1,570 W
   Work is 100 kg × 9.81 m·s⁻² × 0.8 m ≈ 785 J, and 785 J ÷ 0.5 s gives about 1,570 W.

A trained collegiate rower suffers an injury that stops all training for 4 weeks. Which capacity is MOST likely to show the largest decline over this period?

1. Aerobic endurance
   Aerobic capacity starts to decline within a few weeks of inactivity, faster than strength or muscle size, so a rower's endurance suffers most over 4 weeks.
2. Maximal strength
   Maximal strength is fairly well preserved over about a month of detraining, so it is not the largest loss.
3. Muscle fiber size
   Fiber size shrinks slowly over a 4-week layoff, so muscle cross-section is not where the biggest decline shows.

Which resistance training session is MOST likely to produce the greatest acute increase in serum testosterone?

1. Leg extension, 3 × 10RM, 60-s rest
   The leg extension uses far less muscle mass than the squat, which limits the acute testosterone response even with the same sets and rest.
2. Squat, 3 × 10RM, 60-s rest
   A large-muscle lift with moderately heavy loads, high volume and short rest produces the largest acute testosterone rise.
3. Squat, 5 × 2RM, 5-min rest
   Very heavy doubles with 5-minute rests involve low total work and long recovery, so the hormonal response is smaller.

After 16 weeks of aerobic endurance training, an athlete's VO₂max rises by 15%. Which central adaptation contributes MOST to this increase?

1. Higher maximal heart rate
   Maximal heart rate does not rise with training; it stays the same or drops slightly, so it cannot explain the gain.
2. Greater maximal cardiac output
   Endurance training raises maximal cardiac output, mainly through a larger stroke volume, and that is the main central reason VO₂max rises.
3. Greater lung diffusion
   Lung diffusing capacity changes little in healthy athletes and is not what limits VO₂max at sea level.

A 10-year-old boy increases his strength by 30% after 10 weeks of supervised resistance training with little change in muscle size. Which factor BEST explains this gain?

1. Testosterone-driven hypertrophy
   Prepubescent boys have low testosterone, so hormone-driven hypertrophy cannot account for the gain, and the stem says size barely changed.
2. Increased number of fibers
   Fiber number is not a meaningful source of strength gains in humans, and it would also show up as larger muscles.
3. Improved neural activation
   Before puberty, strength gains come mainly from better motor unit recruitment and coordination, which explains a 30% gain with little growth.

A coach tests the vertical jump of 15 athletes; 14 score between 50 and 60 cm, and one scores 85 cm. Which statistic BEST represents the group's typical jump height?

1. Mean score
   The mean is pulled upward by the 85-cm jump, so it overstates what a typical athlete in this group jumps.
2. Score range
   The range shows the spread from lowest to highest score and says nothing about a typical jump height.
3. Median score
   The median is the middle score, so a single 85-cm outlier barely moves it and it still describes the typical athlete.

Athlete A (70 kg) has a VO₂max of 3.5 L·min⁻¹, and Athlete B (100 kg) has a VO₂max of 4.2 L·min⁻¹. Which statement about their aerobic capacity relative to body mass is correct?

1. Both are equal
   The two values are equal neither in absolute terms nor per kilogram, so dividing by body mass separates them clearly.
2. Athlete A is higher
   Athlete A's relative VO₂max is 3.5 L ÷ 70 kg = 50 mL·kg⁻¹·min⁻¹, higher than Athlete B's 42 mL·kg⁻¹·min⁻¹.
3. Athlete B is higher
   Athlete B's absolute VO₂max is larger, but 4.2 L ÷ 100 kg gives only 42 mL·kg⁻¹·min⁻¹ relative to body mass.

During maximal exercise, an athlete's cardiac output is 20 L·min⁻¹ and the arteriovenous oxygen difference is 15 mL of O₂ per 100 mL of blood. What is the athlete's oxygen uptake?

1. 1.3 L·min⁻¹
   1.3 L·min⁻¹ comes from dividing cardiac output by the a-v O₂ difference instead of multiplying them.
2. 3.0 L·min⁻¹
   By the Fick equation, 20 L·min⁻¹ × 150 mL O₂ per liter of blood = 3,000 mL·min⁻¹, or 3.0 L·min⁻¹.
3. 30.0 L·min⁻¹
   30.0 L·min⁻¹ multiplies 20 by 15 and drops the conversion from 100 mL of blood to liters, so it is ten times too high.

During the propulsive phase of a vertical jump, an 80-kg athlete applies an average net vertical force of 800 N for 0.25 s. What is the net impulse produced?

1. 200 N·s
   Impulse is force × time: 800 N × 0.25 s = 200 N·s.
2. 800 N·s
   800 N·s is the force value with the duration left out, so the units match but the size does not.
3. 3,200 N·s
   3,200 N·s divides the force by the time instead of multiplying.

During the concentric phase of a biceps curl, the sarcomeres of the elbow flexors shorten. Which region of the sarcomere stays the SAME length?

1. The I-band
   The I-band contains only actin, and it narrows as the thin filaments slide toward the center of the sarcomere.
2. The H-zone
   The H-zone is the region of myosin without actin overlap, and it shrinks or disappears as overlap increases.
3. The A-band
   The A-band is set by the length of the myosin filaments, which do not change, so it keeps its length as the sarcomere shortens.

A middle-distance runner performs 800-m intervals, each taking about 2 minutes at high intensity. Based on NSCA work-to-rest guidelines, how much recovery should follow each interval?

1. About 6 minutes
   Hard efforts of about 1–3 minutes rely heavily on fast glycolysis and call for a 1:3 to 1:4 work-to-rest ratio, so a 2-minute interval needs about 6 minutes of recovery.
2. About 2 minutes
   Two minutes of rest after a hard 2-minute effort is too short to recover between glycolytic intervals.
3. About 24 minutes
   About 24 minutes is twelve times the work bout, far more rest than a 2-minute interval needs.

In the final weeks before returning to competition, a volleyball player performs repeated jump-landing and blocking drills that match her in-game movements. Which training principle is being applied?

1. Variation
   Variation means changing the training stimulus over time to keep adapting, not making drills match the sport's movements.
2. Reversibility
   Reversibility describes losing adaptations when training stops, which is not what these drills do.
3. Progressive overload
   Progressive overload means raising the stimulus over time; the stem describes matching movements, not increasing load.
4. Specificity
   Drills that copy the athlete's own jumping and blocking movements apply specificity (the SAID principle): adaptations match the demands imposed.

A 45-year-old female masters athlete wants to increase bone mineral density in her lumbar spine and hips. Which exercise provides the MOST effective osteogenic stimulus?

1. Seated leg press
   The seated leg press works the legs but takes axial load off the lumbar spine, so it is a weaker stimulus for spinal bone.
2. Back squat
   The back squat loads the spine and hips axially with heavy weight, which is the high-magnitude strain bone needs to build density.
3. Stationary cycling
   Cycling is non-weight-bearing and low in impact, so it does little to load bone at the spine or hips.

An athlete squats with the same load in two sessions: in one, sets end at a 20% velocity loss; in the other, at a 40% loss. Compared with the 40% condition, what is the expected acute effect of the 20% condition?

1. More repetitions per set
   A smaller allowed velocity loss ends sets sooner, so fewer repetitions are completed, not more.
2. Less fatigue per set
   Stopping each set at a 20% velocity loss ends it with more reps in reserve, so less fatigue builds up than when sets run to a 40% loss.
3. Greater blood lactate
   Shorter sets that stop farther from failure produce less metabolic stress and lower blood lactate.

An athlete cannot lift a 140-kg back squat from the bottom position but can lower the same load under control. Which explanation BEST accounts for this?

1. Elastic recoil aids only the concentric phase
   Elastic recoil stores energy during lowering for use in the lift, so this claim reverses the phases and does not explain the gap.
2. Eccentric actions recruit more motor units
   Eccentric actions recruit fewer motor units for the same load, so recruitment is not what makes lowering easier.
3. Eccentric force capacity is greater
   Muscles can produce more force while lengthening than while shortening, so the athlete can lower a load that cannot be lifted.

A 16-year-old athlete sleeps 6 hours on school nights. How much sleep per night is recommended for this age group?

1. 9–12 hours per night
   9–12 hours is the range for children aged 6–12, not for a 16-year-old.
2. 6–7 hours per night
   6–7 hours is roughly what the athlete already gets, which is below both adolescent and adult recommendations.
3. 8–10 hours per night
   Teenagers aged 13–18 are advised to sleep 8–10 hours per night, so 6 hours on school nights is well short.
4. 7–9 hours per night
   7–9 hours is the adult recommendation and sets the target too low for a 16-year-old.