Vertical jump performance is a key attribute in basketball, influencing rebounding, shot-blocking, and overall explosiveness.
The study aimed to determine biomechanical differences in countermovement vertical jumps (CMJ) with and without an arm swing, providing insights for coaches and sports scientists.
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How does using an arm swing affect force-time metrics in the countermovement vertical jump?
What did the researchers do?
Participants
- 10 professional male basketball players (age: 25.7±2.5 years, height: 191.8±11.5 cm, body mass: 88.7±12.1 kg).
- All had NCAA Division-I experience and were playing professionally in Europe at the time of the study.
Procedures
- After a standardized warm-up, athletes performed three CMJs without an arm swing (hands on hips) and three with an arm swing.
- Force-time data was captured using a uni-axial force plate system sampling at 1000 Hz.
- Jumps were separated by a 15-30 second rest interval to minimize fatigue.
Variables Measured
- Eccentric (loading) phase metrics ⮕ braking rate of force development (RFD), peak force, deceleration time.
- Concentric (push-off) phase metrics ⮕ impulse, peak velocity, peak power.
- Overall performance outcomes ⮕ jump height, contraction time, modified reactive strength index (RSI-modified).
What were the results?
Eccentric Phase (Downward Motion)
- CMJ with an arm swing had a longer eccentric duration compared to the no-arm swing jump.
- Braking RFD and deceleration RFD were lower in CMJ with an arm swing.
- Eccentric peak force was lower in CMJ with an arm swing.
Concentric Phase (Upward Motion)
- CMJ with an arm swing had a longer concentric duration and higher impulse.
- Peak velocity and peak power were significantly greater with an arm swing.
- Despite a longer contraction time, jump height increased significantly with an arm swing.
Overall Impact on Performance
- The arm swing increased jump height by 7 cm on average (42.7 cm vs. 49.8 cm).
- While an arm swing improved jump performance, contraction time was increased.
What does this mean?
- Using an arm swing enhances vertical jump performance due to increased concentric phase velocity and power, not because of greater force output.
- Jump tests with an arm swing might be better suited for sport-specific assessments, whereas hands-on-hip CMJs are potentially more useful for tracking fatigue and neuromuscular readiness.
- Coaches should be mindful that testing protocols must remain consistent—mixing CMJ modalities may lead to misinterpretation of an athlete's performance changes.
Coach's Takeaway
- Arm swing significantly improves jump height.
- For monitoring fatigue and readiness, use the hands-on-hips version for more consistent neuromuscular assessments.
- Test selection matters, so be clear about why you're testing and keep protocols consistent over time to ensure valid comparisons.
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