Three athletes. Three positions. One velocity gap. The training prescribed widens it.
The Force-Velocity Profile Is What Five Force-Time Traces Tell You Together · OH·A · OH·B · MB·1
N1 Performance Lab PH
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Read the curve.
02Continued from Article 05
“THE PHASE MAP CONTAINS ENOUGH INFORMATION TO DERIVE AN ECCENTRIC FORCE-VELOCITY PROFILE.”
— Article 05, N1 Performance Lab
Article 05 ended on a promise. The braking phase of a single unloaded countermovement jump already encodes the eccentric force-velocity signature of the athlete standing on the plate. Nishiumi and colleagues (JSCR 2023) demonstrated that braking-phase force-velocity profile correlates with direct eccentric strength testing. A two-point simplified method showed acceptable validity.
This issue cashes that promise. Then it goes further. The team ran a multi-load protocol — five jumps from 0% to 60% bodyweight — and the verdict every athlete returned was the same one their unloaded braking phase had already given.
03
Chapter 1 — The Braking Phase Already Spoke
WHAT THE CURVE SAID FIRST
The braking phase produces a measurable rate of force development. The late-concentric phase produces a measurable mean force. The ratio between these two values describes the same trade-off that a multi-load force-velocity protocol describes — just from one trial instead of five.
Three athletes. OH·A. OH·B. MB·1. Their unloaded braking-RFD-to-concentric-force ratios all sat in the same region: high concentric force, low braking RFD. The eccentric-velocity ceiling was the limit, not the strength capacity.
Force-Time Trace — Braking Phase Highlighted
LOW
Braking RFD relative to concentric force — across all three athletes
3/3
Athletes with eccentric-velocity ceiling as the binding constraint
04
Chapter 2 — The Loaded Protocol Confirmed It
FIVE CURVES, ONE SLOPE
Five jumps. Body mass + 0%, 15%, 30%, 45%, 60%. Each load produces a force-velocity data point at peak power. The five points plot a line. The slope of that line — divided by the optimal slope for the athlete's mass — is FVimb.
OH·A: FVimb −85.3%. OH·B: −126.3%. MB·1: −122.6%. All three Velocity Deficit. All three with a power ceiling the unloaded braking phase had already flagged.
Samozino Method — Role in This Article
The multi-load protocol is the confirmation step, not the headline method. The curve spoke first. The loaded protocol verified the slope the braking phase had already encoded. Method: Samozino et al. (2014). Five loads. Linear regression. FVimb = (Sfv − Sfvopt) ÷ |Sfvopt| × 100.
Velocity Deficit — All Three Athletes
OH·A−85.3%Outside Hitter Velocity Deficit
OH·B−126.3%Outside Hitter Velocity Deficit · severe
MB·1−122.6%Middle Blocker Velocity Deficit · severe
05
Chapter 3 — The Gap
THE POWER LEFT ON THE COURT
Athlete
F0 (N)
V0 (m/s)
Pmax (W)
Opt. Pmax (W)
Gap (W)
FVimb (opt 0%)
OH·A
3,039
3.18
2,414
3,270
−856
−85.3%
OH·B
3,526
4.11
3,619
5,987
−2,368
−126.3%
MB·1
4,122
4.02
4,140
6,976
−2,836
−122.6%
Each athlete's Pmax gap is the mechanical power left unrealised because the slope sits too far from optimal. OH·A: −856 W. OH·B: −2,368 W. MB·1: −2,836 W. Combined: 6,060 watts of ballistic output that does not exist yet — not because of strength, but because of slope.
Reference band — FVimb optimal = 0%. |FVimb| > 10% = velocity-deficit (force-side training mis-applied). All three athletes sit deep in deficit territory.
Method: Samozino et al. (2014). Optimal Pmax calculated at the athlete's own V0 with F0 corrected to the optimal slope (F0_opt = 2 × BW × g). Trial selection: n=3 per load · median by jump momentum · CV <10%.
06
Chapter 4 — Direction
VELOCITY, NOT VOLUME
The training direction is velocity-oriented. More strength widens the gap. These athletes already have the force. The constraint is producing that force at the velocities required for ballistic output.
Jiménez-Reyes et al. (IJSPP 2017) ran 9 weeks of profile-matched training: ~5% jump height gain in imbalanced athletes versus negligible gains in non-targeted controls. The profile determines the block. Not the position, not the jump height score.
Jiménez-Reyes et al. (2017) IJSPP · Samozino et al. (2014) JSCR · Nishiumi et al. (2023) JSCR — braking-phase F-V correlation with direct eccentric testing
HD Quadrant Report — B5 Berberet
OH·A, OH·B, and MB·1 sit in Q4: high force, not fast. The quadrant confirms what the slope already said. The corrective stimulus must raise V0 — not add more force to an already force-dominated profile.
Velocity-Biased Block — Three Athletes
Method
Drop jumps 2× per week
Load intent
Sub-max RSImod ceiling
Tempo cue
Explosive every concentric rep
Closed loop
Retest FVimb at 4 weeks
The Connection
THE F-V PROFILE EXPLAINS THE CURVE.
A05 mapped the phase fingerprint — what happens inside each of the six CMJ phases. A06 explains why the fingerprint looks the way it does.
The F-V profile is the upstream variable. It determines the shape of the force-time curve, the ratio of braking to propulsive output, and the size of the phase 3-to-phase 4 transition gap.
P3
Braking Phase
A Velocity Deficit athlete loads the braking phase heavily — high force, adequate braking RFD. But speed-side limitations reduce the efficiency of the eccentric-to-concentric transition.
P4
Propulsive Phase
Propulsive impulse underperforms relative to braking input. The athlete cannot convert stored elastic energy into velocity fast enough. The transition leaks — not because of fatigue, but because of a structural F-V imbalance.
P5
Flight Phase
Jump height is suppressed relative to F0 capacity. The athlete has the force but not the velocity to express it. Takeoff velocity — not force — is the ceiling.
The Training Margin
THE PMAX GAP.
Athlete
F0 (N)
V0 (m/s)
Pmax (W)
Opt. Pmax (W)
Gap (W)
FVimb (opt 0%)
OH·A
3,039
3.18
2,414
3,270
−856
−85.3%
OH·B
3,526
4.11
3,619
5,987
−2,368
−126.3%
MB·1
4,122
4.02
4,140
6,976
−2,836
−122.6%
Optimal Pmax calculated at the athlete's own V0 with F0 corrected to the optimal slope (F0_opt = 2 × BW × g). The Pmax gap is the mechanical power the athlete leaves unrealised by carrying an F-V imbalance.
Reference band — FVimb optimal = 0%. |FVimb| > 10% = velocity-deficit zone. All three athletes sit deep in deficit territory; the gap closes only with velocity-biased prescription, not heavier loads.
Method: Samozino et al. (2014). 5-load CMJ: 0%, 15%, 30%, 45%, 60% bodyweight. Trial selection: n=3 per load · median by jump momentum · CV <10%.
Decision — What to Prescribe
TRAIN THE VELOCITY SIDE.
All three athletes sit on the same side of the curve. Force capacity is in place. Velocity expression is not. The bias is the same. The block length scales with the size of the Pmax gap.
Next Test Answers
Whether the velocity-biased block closes the FVimb by >30% — and which athlete's profile shifts the fastest. Re-test multi-load CMJ at week 6.
Prescription Matrix
Athlete
Status
Block Bias
Length
Re-Test
OH·A
VEL DEFICIT
Ballistic · 40–60% 1RM
4 wk
Wk 4 CMJ
OH·B
VEL DEFICIT ++
Ballistic + plyo · 30–50% 1RM
6 wk
Wk 6 CMJ
MB·1
VEL DEFICIT ++
Ballistic + plyo · 30–50% 1RM
6 wk
Wk 6 CMJ
Re-test trigger: end of prescribed block. Continue bias one more block if FVimb closes >30%. Re-screen load tolerance if <15%.
Method: Samozino (2014) · 5-load CMJ · n=3 trials per load · median by jump momentum · CV <10%.
06
N1 Performance Lab · Issue 06
TRAIN THE GAP.
Knowing where an athlete sits on the curve is half the prescription. The gap between their profile and optimal Pmax is the other half.
Next — A07When RFD MattersBraking RFD as the earliest readiness signal. The Yielding sub-phase isolated — and why it leads every other recovery curve.