스쿼트 점프 테스트: 기술, 기준치 & 파워 평가

The squat jump (SJ) test is a foundational assessment in sports science used to isolate concentric force production capacity. By eliminating the stretch-shortening cycle that occurs during a countermovement jump, the squat jump provides a pure measure of an athlete's ability to generate explosive power from a static position. This makes it an invaluable tool for strength and conditioning coaches seeking to identify specific neuromuscular qualities and track adaptations to training programs.

The squat jump test requires an athlete to hold a static semi-squat position — typically with 90 degrees of knee flexion — for a brief pause before jumping maximally upward. The deliberate pause eliminates the elastic energy stored during a countermovement, meaning the jump is powered entirely by concentric muscle contraction. This distinction is critical for sports scientists and coaches because it allows them to separate concentric strength qualities from stretch-shortening cycle efficiency.

First formalized in research by Bosco, Luhtanen, and Komi in the late 1970s, the squat jump has since become one of the most cited assessments in athletic testing batteries. It is used across a wide range of sports — from track and field sprinters to rugby forwards — wherever explosive concentric power is a performance determinant. The test is particularly useful for monitoring neuromuscular fatigue because concentric-only performance tends to decline before stretch-shortening cycle performance does, making the SJ a sensitive early-warning marker of overtraining.

Common variables derived from the squat jump include jump height (calculated via flight time or take-off velocity), peak power output, peak force, and rate of force development (RFD). When combined with CMJ results, the SJ also feeds into the eccentric utilization ratio (EUR), a metric that reveals how effectively an athlete exploits elastic energy.

Executing a valid squat jump test requires strict adherence to protocol. Any countermovement — even a subtle dip — invalidates the trial and converts it into a hybrid movement that compromises data quality. Follow these steps for a reliable, repeatable assessment:

1. Warm-up: Complete 5-10 minutes of light aerobic activity followed by dynamic stretching targeting the hip flexors, quadriceps, and calves. Perform 3-5 submaximal practice jumps to familiarize the athlete with the static start position.
2. Starting position: Stand with feet shoulder-width apart on a firm, level surface. Descend to a squat with approximately 90 degrees of knee flexion. Place hands on hips (akimbo position) to standardize upper-body contribution. Hold this position completely still for a minimum of 3 seconds.
3. Execution: On the verbal command or self-initiated cue, jump as high as possible by extending the hips, knees, and ankles simultaneously. There must be no visible downward movement before the jump. Any dip means the trial is discarded.
4. Flight and landing: Maintain an extended body position during flight. Avoid tucking the knees. Land softly on both feet with knees slightly bent to absorb impact.
5. Repetitions: Perform 3-5 maximal trials with 60-90 seconds of rest between attempts. Record the best trial or the average of the best three, depending on your testing protocol.

Key standardization notes: The knee angle at the start significantly affects results. A deeper squat (e.g., 120 degrees) reduces jump height but increases the range of motion for force application. Always use a consistent angle and, ideally, verify it with a goniometer or motion sensor. Time of day, footwear, and surface should also be standardized across testing sessions to ensure valid longitudinal comparisons.

Accurate measurement is essential for the squat jump test to yield actionable data. Several technologies are available, each with distinct advantages and limitations:

Force plates remain the gold standard for squat jump assessment. By sampling ground reaction forces at 1000 Hz or higher, force plates calculate take-off velocity through impulse-momentum integration, from which jump height is derived. They also provide peak force, mean force, rate of force development, and time-to-peak-force — variables that reveal the underlying mechanisms behind jump performance. However, force plates are expensive, non-portable, and generally confined to laboratory or high-performance facility settings.

Inertial measurement units (IMUs) have emerged as a portable, cost-effective alternative. High-frequency IMU sensors, such as the PoinT GO device sampling at 800 Hz, attach to the athlete's body and use accelerometer and gyroscope data to compute take-off velocity, jump height, and power output. Research has demonstrated that modern IMU sensors achieve accuracy within 1-2 cm of force plate measurements, making them suitable for field-based testing where laboratory equipment is impractical.

Contact mats measure flight time and calculate height using the equation h = (g × t²) / 8, where g is gravitational acceleration and t is flight time. While affordable and simple, contact mats provide only height data and cannot distinguish between a true squat jump and one contaminated by a countermovement, since they only detect the airborne phase.

Linear position transducers and high-speed video analysis (240+ fps) offer additional options, though each introduces its own set of trade-offs between cost, portability, and data richness. For most practitioners, an IMU-based device offers the best balance of accuracy, portability, and the breadth of metrics needed for comprehensive squat jump analysis.

Squat jump height norms vary significantly based on sport, training level, and sex. The following table summarizes published normative ranges compiled from peer-reviewed research across multiple populations:

Squat jump height is generally 2–6 cm lower than CMJ height in the same individual. This difference — the eccentric utilization ratio — typically ranges from 5% to 15%. A very small difference (under 5%) may indicate poor stretch-shortening cycle efficiency, while a very large difference (over 15%) may suggest that concentric strength is a limiting factor relative to reactive ability. Both scenarios provide clear training direction.

When interpreting SJ results, also consider peak power output relative to body mass. Research by Markovic and Jaric (2007) established that relative peak power (W/kg) is more valid for between-athlete comparisons than absolute jump height. Typical values for elite male athletes range from 50–65 W/kg, with female athletes typically in the 35–50 W/kg range.

The comparison between the squat jump and the countermovement jump is one of the most informative analyses in athletic testing. While both assess lower-body power, they target different neuromuscular qualities, and the relationship between them reveals critical information about an athlete's physical profile.

The CMJ is almost always higher than the SJ because the countermovement activates the stretch-shortening cycle (SSC). During the rapid downward phase, muscles and tendons store elastic potential energy, which is released during the upward propulsive phase. Additionally, the countermovement triggers a greater degree of muscle pre-activation and allows the athlete to produce force over a longer duration, both of which increase total impulse.

The eccentric utilization ratio (EUR) is calculated as CMJ height divided by SJ height. A ratio close to 1.0 means the athlete gains little benefit from the SSC, which may indicate either exceptional concentric strength or poor elastic/reactive qualities. A high EUR (above 1.15) suggests strong SSC function but potentially underdeveloped concentric strength. Monitoring the EUR over a training cycle helps coaches tailor programming — a declining EUR might warrant more plyometric and reactive training, while a rising EUR could signal that maximal strength work is needed.

For fatigue monitoring, the SJ is arguably more sensitive than the CMJ. Research by Gathercole et al. (2015) demonstrated that SJ performance declined earlier and more substantially than CMJ performance following fatiguing exercise protocols. This makes the SJ a valuable tool for daily readiness monitoring in high-performance sport environments.

Improving squat jump performance requires a targeted approach that prioritizes concentric rate of force development and maximal strength. Because the SJ eliminates elastic energy contributions, gains must come from the contractile machinery itself — the ability of motor units to recruit rapidly and produce high forces in a short time window.

Heavy resistance training forms the foundation. Back squats, front squats, and leg presses at 80–95% of 1RM improve maximal force production capacity, which directly transfers to SJ height. Research consistently shows that athletes who increase their relative squat strength (1RM/body mass) also improve their SJ performance, particularly when starting from a lower training base.

Explosive strength training using loaded jump squats at 30–60% of 1RM is highly specific to the SJ. These load ranges optimize mechanical power output during jumping movements. Perform 3–5 sets of 3–5 repetitions with full recovery (2–3 minutes) between sets to ensure maximal quality on every repetition.

Isometric training at specific joint angles can target the 90-degree knee position used in the SJ starting position. Isometric mid-thigh pulls and wall sits at the target angle build position-specific force production that directly transfers to the static start.

Olympic lift derivatives such as hang cleans and jump shrugs develop the triple extension pattern (simultaneous hip, knee, and ankle extension) that powers the squat jump. These movements also train high-velocity force production, improving rate of force development.

A well-designed 8–12 week program combining heavy squats (2–3 sessions per week), loaded jump squats (1–2 sessions), and Olympic derivatives (1–2 sessions) can yield improvements of 5–15% in SJ height for intermediate athletes. Test every 4 weeks using a standardized protocol to track progress and adjust training loads accordingly.