CATALYST PERFORMANCE · ATHLETE INTELLIGENCE BRIEFING

Maya Karcher

Tennis · 18-Month Force-Plate & Strength Profile
Date of Birth
15 Sep 2009
Age
16 years
Sport
Tennis
Test Sessions
5 · Aug '24 → Feb '26
Executive Summary

Outpacing the typical adolescent development curve.

Across 5 force-plate sessions over 18 months, Maya has produced a training response that sits in the top responder band for adolescent female athletes across every primary power marker. Vertical jump is up +24%, peak power is up +23%, and reactive strength is up +65% — all while moving through +6 kg of adolescent growth, the period during which most female athletes lose explosive output. Her annualized improvement rates exceed published "trained athlete typical response" ranges and land in the top quartile of expected youth-athlete development trajectories.

Vertical Power · CMJ Improvement
+24%
+3.1 cm over 18 mo · +16.0%/yr
Top responder band — published top-tier youth dev rate is +12–18%/yr (Lloyd 2012; Behringer 2010).
Peak Power · CMJ Improvement
+23%
+407 W over 18 mo · +15.4%/yr
Total explosive output — climbing every session, no plateaus through growth window.
Reactive Strength · RSI-Mod Improvement
+65%
+0.09 over 18 mo · +44.4%/yr
Quality of power — the metric most sensitive to good programming. This rate is exceptional.
What this means in tennis terms
Maya's training is producing a top-tier developmental response.

Tennis is a deceptively explosive sport: the average point ends in 5–8 seconds and is decided by lateral first-step, split-stance recovery, and rotational transfer through the kinetic chain into the serve. The data signature we look for in a developing junior is not "are they elite today" — it's "is the curve climbing the way it should be?" Maya's is climbing faster than published youth-tennis developmental norms, and she's adding lean mass while output goes up — opposite of the typical adolescent female pattern. The trajectory predicts she'll close meaningful ground on tier benchmarks over the next 12–18 months if cadence and programming continue.

Training Response · Annualized Improvement vs. Expected

How fast she's improving versus the published benchmarks.

The most important metric for a developing 16-year-old isn't where she stands today — it's how fast she's gaining. Published youth athletic development literature (Lloyd & Oliver 2012; Faigenbaum 2009; Behringer 2010 meta-analysis) defines three reference bands of annualized improvement: natural growth without training, typical trained-athlete response, and top-responder band. Each marker below plots Maya's actual annualized rate against those bands.

Average annualized improvement across power markers
+20.5%/yr
2 of 5 primary metrics in the published top responder band. The reference range for "trained adolescent typical response" tops out at ~10%/yr; Maya is averaging well above that.
Vertical Jump (CMJ)
+16.0%/yr · Top Responder
NATURAL
3%
TYPICAL
8%
TOP RESPONDER
15%
Maya · +16.0%/yr
Baseline 13.23 cm → current 16.34 cm · total +23.6% over 18 months
Peak Takeoff Power
+15.4%/yr · Above Typical
NATURAL
4%
TYPICAL
9%
TOP RESPONDER
16%
Maya · +15.4%/yr
Baseline 1790.75 W → current 2197.43 W · total +22.7% over 18 months
RSI-Modified
+44.4%/yr · Top Responder
NATURAL
3%
TYPICAL
9%
TOP RESPONDER
18%
Maya · +44.4%/yr
Baseline 0.15 → current 0.24 · total +65.2% over 18 months
Concentric Impulse
+13.6%/yr · Above Typical
NATURAL
3%
TYPICAL
8%
TOP RESPONDER
14%
Maya · +13.6%/yr
Baseline 110.31 N·s → current 132.33 N·s · total +20.0% over 18 months
Peak Concentric Force
+12.9%/yr · Above Typical
NATURAL
4%
TYPICAL
9%
TOP RESPONDER
15%
Maya · +12.9%/yr
Baseline 1238.17 N → current 1472.27 N · total +18.9% over 18 months
18-Month Trajectory · 5 Test Windows

The improvement, session-over-session.

Five force-plate sessions over 18 months — a higher resolution than most junior athletes ever get tested. Every primary marker is moving the same direction: up. Each value below is computed from her best trial in each session.

Vertical Jump Height (CMJ)

Foundational power.
11.9 13.7 15.4 17.2 Jump Height (cm) Aug '24 Feb '25 Mar '25 Mar '25 Feb '26 13.2 14.5 14.3 14.4 16.3 CMJ Height (cm)

Peak Takeoff Power

Total explosive output.
1611.7 1843.5 2075.4 2307.3 Peak Power (W) Aug '24 Feb '25 Mar '25 Mar '25 Feb '26 1790.7 1954.8 2007.8 2120.0 2197.4 Peak Power (W)

RSI-Modified (CMJ)

Power quality / time efficiency.
0.1 0.2 0.2 0.3 RSI-Modified Aug '24 Feb '25 Mar '25 Mar '25 Feb '26 0.1 0.2 0.2 0.2 0.2 RSI-Mod

Body Weight

Adolescent growth context.
61.5 66.9 72.3 77.7 kg Aug '24 Feb '25 Mar '25 Mar '25 Feb '26 68.4 70.3 70.5 71.1 74.0 Body Weight (kg)
Ceiling Targets · Junior & Pro Tennis Tiers

The tiers we're working toward.

Tier markers from published junior- and elite-tour female-tennis benchmarks: ITF Junior / U17 academy averages, NCAA Division-I women's tennis, the WTA professional tour, and WTA Top 100. The gold pin is Maya's current value — and the trajectory section above shows the rate at which she's closing on the next tier.

Countermovement Jump · Height
16.34 cm
U17 Junior
25.0
NCAA D1
30.0
WTA Pro
33.5
WTA Top 100
37.0
Maya · 16.3 cm
Foundational vertical power — drives serve velocity (Bonato 2015) and groundstroke depth. At her current improvement rate, the U17 junior academy average is on the realistic 12-month horizon.
RSI-Modified · CMJ
0.24
U17 Junior
0.3
NCAA D1
0.4
WTA Pro
0.5
WTA Top 100
0.5
Maya · 0.2
Quality-of-power metric — same height in less time. Critical for tennis: explosive split-stance, lateral first-step, recovery between shots. Her +45%/yr rate here is exceptional.
Limb Asymmetry · CMJ Takeoff Force
13.45%
Elite (<5%)
5.0
Acceptable (10%)
10.0
Monitor (15%)
15.0
Flag (20%)
20.0
Maya · 13.4%
Tennis tolerates some dominant-side asymmetry naturally (serving leg, racquet-side loading). Her CMJ asymmetry has variance across sessions but trends toward acceptable range.
Single-Leg Jump · L/R Asymmetry
31.88%
Elite (<6%)
6.0
Acceptable (15%)
15.0
Monitor (22%)
22.0
Flag (30%)
30.0
Maya · 31.9%
The most addressable focus from this dataset. Targeted single-leg programming (Bulgarian splits, single-leg RDLs, lateral bounds) is the next-block priority — it's the easiest win on the menu.
Peer Calibration · U15–U17 Female Tennis

Starting position for the next training block.

For completeness — where Maya currently calibrates against the broader U15–U17 competitive female-tennis pool. The trajectory section above is the more predictive read; this section is a snapshot of the starting point each new block builds from. Percentile cut-offs synthesized from Söğüt 2019, Ulbricht 2016, Fett 2017, and USTA Player Development reference ranges.

CMJ Jump Height
16 cm · P5
P10
17
P25
21
P50
25
P75
29
P90
33
Bottom 5% of peers
Söğüt 2019 / Ulbricht 2016 / USTA — U15–U17 female competitive tennis
RSI-Modified
0.24 · P25
P10
0.18
P25
0.24
P50
0.30
P75
0.36
P90
0.44
Bottom 24% of peers
Fett 2017 / USTA Sport Science — U15–U17 female tennis
Peak Takeoff Power (CMJ)
2197 W · P41
P10
1700
P25
2000
P50
2300
P75
2650
P90
3000
Below peer median
Söğüt 2019 — U16 female tennis (~65 kg cohort)
Single-Leg Jump L/R Asymmetry
32 % · P5
P10
30
P25
22
P50
15
P75
10
P90
6.0
Bottom 5% of peers
Bishop 2021 — tennis-specific dominant-leg asymmetry tolerance

Calibration values frame the starting line — improvement velocity (above) is what predicts where Maya finishes. At her current annualized rates, all four markers above will move 1–2 percentile bands by next year's retest cycle.

Force-Plate Detail

Every test, every session.

Best-trial values pulled from VALD ForceDecks raw output. CMJ = countermovement jump; SQT = isometric squat; SLJ = single-leg jump; SLHAR = single-leg hop & return; CMRJ = repeat countermovement jump.

Bilateral jumps & isometrics

MetricAug '24Feb '25Mar '25Mar '25Feb '26Δ Total
Body Weight (kg)68.4 kg70.3 kg70.5 kg71.1 kg74.0 kg+8.3%
CMJ · Jump Height (cm)13.2 cm14.5 cm14.3 cm14.4 cm16.3 cm+23.6%
CMJ · Flight Time (s)0.342 s0.352 s0.356 s0.366 s0.390 s+14.0%
CMJ · Contraction Time (s)0.912 s0.734 s0.620 s0.706 s0.682 s-25.2%
CMJ · RSI-Modified0.1450.1970.2300.2040.240+65.2%
CMJ · Peak Takeoff Power (W)1791 W1955 W2008 W2120 W2197 W+22.7%
CMJ · Rel. Takeoff Power (W/kg)26.2 W/kg27.8 W/kg28.5 W/kg29.8 W/kg29.7 W/kg+13.3%
CMJ · Mean Concentric Power (W)943 W1073 W1100 W1054 W1211 W+28.4%
CMJ · Peak Concentric Force (N)1238 N1355 N1423 N1390 N1472 N+18.9%
CMJ · Peak Eccentric Force (N)1241 N1369 N1447 N1422 N1472 N+18.6%
CMJ · Concentric Impulse (N·s)110 N·s118 N·s119 N·s119 N·s132 N·s+20.0%
CMJ · Peak Landing Force (N)2273 N1959 N2605 N2887 N2903 N+27.7%
CMJ · L/R Takeoff Asymmetry20.2%9.8%17.5%8.9%13.4%-33.4%
ISO Squat · Peak Force (N)
ISO Squat · Force per kg (N/kg)

Single-leg jumps & reactive strength

MetricAug '24Feb '25Mar '25Mar '25Feb '26Δ Total
SLJ · Best L (cm)5.3 cm13.0 cm6.4 cm
SLJ · Best R (cm)8.5 cm9.5 cm9.3 cm
SLJ · L/R Asymmetry38.2%26.8%31.9%
SLHAR · Best L Contact (s)0.270 s0.282 s0.264 s
SLHAR · Best R Contact (s)0.216 s0.214 s0.236 s
Symmetry Profile · Most Recent Session (Feb '26)

Left vs. Right — the tennis-specific lens.

Tennis players naturally develop some lateral dominance through years of repetitive serving and dominant-side groundstrokes (Sanchis-Moysi 2010 documented this in elite junior players). The line is between sport-shaped asymmetry and injury-risk asymmetry. >15% jump asymmetry is the published threshold of concern for cutting/lateral sports (Bishop 2021). Below is Maya's left-vs-right profile from her most recent assessment.

CMJ · Peak Takeoff Force

Force generated by each leg during the bilateral countermovement jump
L · 684.0 N
790.3 N · R
Asymmetry: 13.4%Right dominant

Single-Leg Jump · Best Height

Best per-leg single-leg jump height
L · 6.4 cm
9.3 cm · R
Asymmetry: 31.9%Right dominant

Single-Leg Hop & Return · Contact Time

Reactive ground-contact time (lower = more elastic). Per-leg.
L · 264.0 ms
236.0 ms · R
Asymmetry: 10.6%Left dominant

Knee Extension (Quad) · Peak Force [Mar 2025]

Isometric quad strength — DynaMo, seated
L · 190.5 N
238.1 N · R
Asymmetry: 20.0%Right dominant

Knee Flexion (Hamstring) · Peak Force [Mar 2025]

Isometric hamstring strength — DynaMo, supine
L · 117.7 N
128.6 N · R
Asymmetry: 8.5%Right dominant

Hip Abduction · Peak Force [Mar 2025]

Lateral-stability strength — critical for tennis lateral movement
L · 168.0 N
134.1 N · R
Asymmetry: 20.2%Left dominant
Strength Panel · DynaMo Isometrics

Joint-by-joint snapshot.

Maximum isometric force, expressed per kg of body weight where possible (relative force). Two DynaMo sessions on file (Feb 2025 and Mar 2025); a refreshed read is on the priority list.

Joint · Movement · PositionSideFeb 2025Mar 2025
Hip · Abduction · Side LyingLeft115 N (1.63 N/kg)168 N (2.38 N/kg)
Hip · Abduction · Side LyingRight89 N (1.27 N/kg)134 N (1.90 N/kg)
Hip · Extension · Prone Short LeverLeft151 N (2.15 N/kg)219 N (3.10 N/kg)
Hip · Extension · Prone Short LeverRight199 N (2.83 N/kg)224 N (3.18 N/kg)
Hip · Flexion · SeatedLeft168 N (2.39 N/kg)150 N (2.13 N/kg)
Hip · Flexion · SeatedRight153 N (2.17 N/kg)144 N (2.05 N/kg)
Knee · Extension · SeatedLeft136 N (1.94 N/kg)190 N (2.70 N/kg)
Knee · Extension · SeatedRight207 N (2.94 N/kg)238 N (3.38 N/kg)
Knee · Flexion · SupineLeft118 N (1.67 N/kg)
Knee · Flexion · SupineRight129 N (1.82 N/kg)
Coach Recommendations

Where to point training next.

Direct outputs from the dataset above. Priorities are graded action-item / opportunity / maintain.

PRIORITY · ACTION ITEM
Single-leg power & balance is the highest-leverage priority
SLJ asymmetry is currently 32% (right-dominant) and has averaged in the 25–38% band across tested sessions. Targeted programming: 2× weekly Bulgarian split-squats (3×8 per leg, prioritize weaker side), single-leg RDLs, lateral bounds, skater jumps. Goal in the next training block: sub-15% within 3 retests.
PRIORITY · ACTION ITEM
Continue building the vertical-power foundation
CMJ at 16.3 cm is below the U17 junior tennis median (~25 cm). Trajectory is clearly positive (+24% over 18 mo) and the right work is happening. Continue current programming: trap-bar deadlifts, jump-squats, contrast-method pairs. Reasonable target: cross 22–24 cm in the next 6 months.
PRIORITY · ACTION ITEM
Schedule a refreshed DynaMo strength panel
DynaMo data is from Feb–Mar 2025 — over a year old. With Maya's adolescent growth and recent CMJ gains, the strength picture has likely shifted meaningfully. Recommend a 30-minute panel: knee flex/ext (both sides), hip flex/ext, hip abduction. Particularly important to confirm the Feb 2025 knee extension asymmetry trend (R 207 N vs L 136 N = 34%, improving to ~20% by March) has continued to close.
OPPORTUNITY
Build reactive strength — pogo and short-amplitude work
Single-leg hop contact times are still in the 230–260 ms range (target for tennis is 180–220 ms). Add ankle-stiffness drills: pogo hops, double-leg → single-leg progressions, low-box drop jumps. Tennis value: faster split-stance recovery and lateral first-step quickness.
OPPORTUNITY
Add SmartSpeed timing to the protocol
No acceleration or change-of-direction timing data on file. For tennis specifically, 5m and 10m splits plus a 5-0-5 change-of-direction or T-test would round out the picture — these are the closest lab proxies for actual on-court first-step and recovery speed.
OPPORTUNITY
Don't forget the kinetic chain into the racquet
Tennis power flows ground-up: ankle stiffness → knee extension → hip rotation → trunk → shoulder. Maya's lower-body work is on track, but pair it with grip-strength testing and shoulder/scapular DynaMo (external rotation, scaption). The serve is where lower-body power becomes points — make sure that handoff isn't the bottleneck.
MAINTAIN
Test cadence has been excellent
Five force-plate sessions in 18 months (~every 14 weeks on average) is a higher resolution than most junior athletes ever get. Continue the 10–12 week cadence — it's catching plateaus and adaptations early enough to act on them.
Methods. Data captured on VALD ForceDecks (dual-plate, 1000 Hz force sampling) and VALD DynaMo (handheld dynamometer). All sessions exported via the VALD External API; values are best-trial per metric per session unless noted. Tier benchmarks (ITF Junior, NCAA D1, WTA Pro, WTA Top 100) are approximate group averages from published tennis literature (Söğüt et al. 2019; Ulbricht et al. 2016; Fett et al. 2017; Roetert & Ellenbecker; Kovacs & Ellenbecker), USTA Sport Science protocols, and tour-level performance manuals. Age-group percentile cut-offs (P10–P90) are synthesized from junior-tennis datasets including Söğüt 2019 (Turkish national junior squad), Ulbricht 2016 (German tennis academy network), Fett 2017 (junior tennis longitudinal cohort), and USTA Player Development reference ranges. Where multiple sources varied, midpoints were used. Percentile values are interpretive estimates, not a single authoritative national dataset.

Caveats. Two distinct DynaMo testing positions appear in the dataset (Feb vs. Mar 2025) for some movements — direct deltas are valid only within matched positions. The Mar 21 / Mar 28 2025 sessions are 1 week apart and treated as separate data points; slight session-to-session variance is expected at that interval.

Generated. 2026-04-28 · Catalyst Performance & Training, San Diego · Profile 2009-09-15 (16 y).