Drop jumps (DJs) are a core plyometric tool used to develop explosive strength and improve jump performance, critical qualities in volleyball, basketball, and other jumping sports.
By personalizing drop height (based on each athlete’s best reactive strength index), the researchers explored how training below, above, or at optimal drop jump height (based on RSI) compares.
Is it better to train drop jumps from the optimal height, a bit lower, or a bit higher to maximize jump and strength gains?
What Did the Researchers Do?
The researchers had 55 female volleyball players (mean age ~24 years), all highly trained and competing at a national level, organized into 5 different training groups based on drop jump testing.
Groups
- CG ⮕ Volleyball training only (Control)
- WG ⮕ Volleyball + Weight training
- LG ⮕ Weight training + Drop jumps from 25% lower than optimal
- OG ⮕ Weight training + Drop jumps from optimal height
- HG ⮕ Weight training + Drop jumps from 25% higher than optimal
Training Program
- Duration: 8 weeks (13 sessions total for each modality)
- All groups received a preparatory period (3 weeks) to acclimate
- DJ and weight training were performed on alternate days
- DJ performance tested from 20–70 cm, including RSI (jump height ÷ contact time)
- Squat Jump (SJ), Countermovement Jump (CMJ), CMJ with arm swing (CMJas), and half-squat 1RM measured
RSI Profiling
- All athletes underwent drop jump profiling before the intervention.
- Researchers tested DJs from multiple drop heights (20–70 cm) to calculate each athlete’s Reactive Strength Index (RSI) at each height.
- The optimal drop height was defined as the height that yielded the highest RSI for that individual.
After determining each athlete’s optimal drop height, participants were randomly assigned to one of the five groups.
What Were the Results?
Strength Gains
- All training groups (LG, OG, HG, WG) improved 1RM squat by ~17–19%, significantly more than the control.
Jump Height Improvements
OG and HG had the most significant gains in:
- SJ: OG (+20%), HG (+17%)
- CMJ: OG (+17%), HG (+15%)
- CMJas: OG (+14%), HG (+12%)
- LG and WG also improved, but not nearly as much (~7–10%)
Drop Jump Performance
- Only OG and HG significantly improved DJ height from nearly all tested heights (20–70 cm).
- HG showed the most significant gains in RSI (up to +46%), suggesting superior fast SSC adaptation.
Contact Time
- Contact time decreased the most in HG (at all heights), indicating better reactive speed.
What Does This Mean?
Training from the optimal or slightly higher drop height (by 25%) leads to the best improvements in:
- Vertical jump height (slow SSC: SJ, CMJ, CMJas)
- Reactive strength (fast SSC: DJ & RSI)
Using a drop height lower than optimal results in modest improvements, comparable to those achieved with similar weight training alone.
Adding weight training to DJ training further enhances results, especially when DJ height is individualized.
Coach's Takeaway
- Use RSI testing to determine each athlete’s optimal drop height.
- Going slightly higher than optimal (by 25%) enhances fast SSC outcomes (DJ, RSI) the most.
- Pairing with weight training is best as it combines the force (strength) and velocity (DJ) components needed for peak performance.
I hope this helps,
Ramsey
