영어 모의고사 (자동 편성)

Exercise does far more than strengthen muscles and the heart; it also produces measurable changes within the brain itself. During sustained physical activity, the body ① releases a protein called brain-derived neurotrophic factor, which supports the growth of new neurons and ② strengthens connections between existing ones, particularly in regions associated with memory and learning. Studies comparing physically active students to sedentary peers have repeatedly found that the active group ③ performing better on tests of attention and problem-solving, even when the exercise session ends well before the test begins. Researchers believe that exercise increases blood flow to the brain, ④ delivering oxygen and nutrients more efficiently, while also reducing levels of stress hormones that can interfere with clear thinking. These findings have encouraged some schools ⑤ to schedule exercise before demanding academic classes.

VO2 max, defined as the maximum volume of oxygen a person's body can consume and use during intense exercise, is widely regarded as one of the best single indicators of cardiorespiratory fitness. Elite endurance athletes typically post VO2 max values far ① higher than those of untrained individuals, reflecting hearts that pump larger volumes of blood and muscles that extract oxygen from that blood with remarkable efficiency. While genetics accounts for a substantial portion of an individual's potential VO2 max, consistent aerobic training can still ② raise the measurement considerably over months of dedicated effort. Interval training, which alternates short bursts of near-maximal effort with periods of recovery, has proven particularly ③ effective at improving this measurement compared to steady, moderate-intensity exercise alone. It is worth noting, however, that a high VO2 max does not guarantee success in competition, since factors such as running economy, pacing strategy, and mental resilience also play a ④ decisive role in determining who actually crosses the finish line first. These additional factors remain ⑤ irrelevant to overall performance.

Team sports place athletes in a uniquely social form of competition, one where individual skill alone rarely determines the outcome of a match. Sports psychologists have long studied why some groups of talented individual players fail to perform as a cohesive unit while other, less individually skilled teams consistently exceed expectations. Trust among teammates appears to be a decisive factor, since _______________. Clear and consistent communication during high-pressure moments further reduces the hesitation and confusion that can unravel a team's coordination in front of a crowd.

Elite athletes rarely walk up to a free throw line or a golf ball without first performing a highly specific sequence of movements, a habit sports psychologists call a pre-performance routine. Far from being mere superstition, this consistent sequence serves a genuine cognitive purpose: repeating the same physical and mental steps before every attempt narrows an athlete's focus away from distracting thoughts and toward the specific technical cues needed to execute the skill correctly. Researchers have found that athletes who follow a consistent routine tend to show more stable performance under pressure than those who approach each attempt differently, because _______________. For this reason, coaches now actively teach young athletes to develop and rehearse individualized routines rather than treating them as personal quirks.

Across the world, teenagers are chronically short on sleep, often getting two or three hours less than the eight to ten hours experts recommend for their age. Part of the problem lies in biology: as puberty begins, _______________. Yet school start times rarely adjust to this shift, forcing students to wake before their bodies are ready. The consequences extend well beyond simple tiredness. Chronic sleep loss during adolescence has been linked to impaired concentration, weakened memory, and a higher risk of anxiety and depression. It can also disrupt the hormones that regulate appetite, contributing to unhealthy weight gain over time. Some school districts have experimented with delaying start times by even thirty minutes, and early results suggest that students who gain that extra rest show improved grades, better mood, and fewer tardy arrivals. Despite this evidence, changing entrenched school schedules remains a slow and contentious process.

Coaches have traditionally focused athlete preparation on training volume and nutrition, but a growing body of research suggests that sleep deserves equal attention. (A) In response, many professional teams now employ sleep specialists who design travel schedules, control bedroom lighting and temperature, and even adjust competition start times when possible. (B) Frequent travel across time zones compounds this challenge considerably, since jet lag can disrupt an athlete's natural sleep-wake cycle for several days after a long flight. (C) During deep sleep, the body releases growth hormone, essential for repairing muscle tissue, while the brain consolidates motor skills practiced earlier that day into more stable, efficient patterns.

In the days leading up to an endurance event, many athletes deliberately increase their carbohydrate intake while reducing training volume, a practice known as carbohydrate loading. (A) Because glycogen serves as the primary fuel source during prolonged, intense exercise, entering an event with fuller stores can delay the point of exhaustion that runners often call hitting the wall. (B) Sports nutritionists caution, however, that the timing and composition of meals matter as much as the total quantity of carbohydrate consumed. (C) The strategy is designed to maximize the amount of glycogen, the storage form of carbohydrate, packed into muscle tissue before competition begins.

This is precisely why an experienced athlete returning after an injury often regains sharp form faster than a complete beginner ever could. Anyone who has ridden a bicycle after a decade away from one has likely experienced muscle memory firsthand: the body seems to recall a complex skill almost instantly, even when conscious memory of the exact movements has faded. ( ① ) Contrary to what the name suggests, muscles themselves do not actually store memories; the phenomenon originates in the brain and nervous system, where repeated practice gradually shifts control of a well-learned movement from regions associated with conscious thought to areas that operate largely automatically. ( ② ) This shift explains why a skilled athlete can execute a complicated sequence of movements without consciously thinking through each individual step, freeing mental attention for strategy and decision-making instead. ( ③ ) Interestingly, research also suggests that these neural pathways can remain partially intact even after long periods without practice, which is why relearning a skill is typically much faster than learning it for the very first time. ( ④ ) Coaches often exploit this principle by ensuring that fundamental techniques are practiced correctly from the very beginning. ( ⑤ )

This is precisely what makes the condition so difficult to catch before it becomes severe. Ambitious young athletes and the parents who support them sometimes assume that more training automatically produces better results, a belief that occasionally leads to a condition known as overtraining syndrome. ( ① ) Unlike ordinary fatigue that resolves after a few days of rest, overtraining syndrome develops gradually over weeks or months of insufficient recovery relative to training load, eventually producing persistent exhaustion, declining performance despite continued hard work, and increased susceptibility to illness and injury. ( ② ) Adolescents may be especially vulnerable, since their bodies are simultaneously coping with the physical demands of growth and the added stress of intensive training schedules. ( ③ ) Warning signs are often subtle at first, including disrupted sleep, irritability, and a loss of enthusiasm for a sport the athlete once genuinely enjoyed, which adults often mistake for ordinary moodiness. ( ④ ) Recovery from full-blown overtraining syndrome can take months rather than days. ( ⑤ )

In other words, the body keeps a running total rather than resetting each day. Sleep debt refers to the cumulative gap between the amount of sleep a person needs and the amount they actually get. ( ① ) Unlike a financial debt, however, this deficit cannot simply be repaid with a single long weekend of rest. ( ② ) When someone loses two hours of sleep every night for a week, the body does not treat the shortage as fourteen separate small losses; instead, it accumulates the deficit, and the resulting impairment in attention and mood can resemble that of a person who has been awake for an entire night. ( ③ ) Researchers have found that even modest, chronic sleep restriction gradually impairs reaction time and decision-making, often without the affected person noticing the decline. ( ④ ) This is because subjective feelings of tiredness tend to plateau after a few days, even as objective performance keeps deteriorating. ( ⑤ ) Consequently, people frequently underestimate how much sleep debt they are carrying until a demanding task suddenly exposes the accumulated cost.