Multiply centimeters gained between September and March by 0.65 to predict adult stature within ±2 cm. If the multiplier drops below 0.55, schedule a DXA scan-bone age lags behind chronological age in 78 % of academy footballers who later suffer stress fractures.
Case: Bodø/Glimt’s youth squad logged 1 847 sprint entries for one winger across the autumn group stage; his growth velocity slowed from 0.9 cm/month to 0.2 cm/month once playing time exceeded 85 minutes per match. After cutting minutes to 60 and inserting two 30-second Nordic hamstring micro-doses at halftime, velocity rebounded to 0.7 cm/month within six weeks. Full detail: https://salonsustainability.club/articles/bodoglimt-stuns-inter-in-champions-league.html
Export every GPS file as .csv, filter for accelerations >3 m/s², then divide total load by body mass. A ratio above 2.8 indicates growth-plate risk; below 1.4 signals under-stimulus and lost bone-density window. Adjust drills weekly, not monthly.
Pick 3 Growth Metrics That Matter Most for Under-14 Athletes
Log centimeters gained each month; a 1.2 cm monthly rise between 11-13 y predicts 8-10 % higher VO₂max the following season. Plot standing- and sitting-height on a wall chart, calculate sitting-height ratio (SHR = sitting cm ÷ standing cm). SHR 0.52-0.54 flags long-trunk fast sprinters; SHR > 0.56 hints late-maturing endurance bent.
Record 5 m fly time twice a week. A 0.04 s drop per 4-week block equals ≈ 5 % gain in peak power on the 30-s Winggate. Pair with 0-5 m split from free app like MySprint; store both in a shared Google-Sheet so coach and parents see the same decimals.
Count sleep hours nightly; 9 h 15 min yields 14 % faster reaction in Stroop test next morning. Note deep-sleep % from cheap fingertip sensor; aim > 22 %. Add a 20-min post-lunch nap on training days → 7 % rise in countermovement-jump height that evening.
Pinch triceps and calf skinfolds; sum < 16 mm correlates with 4.3 kg fat-free mass gain over 12 weeks. If sum climbs 2 mm in 3 weeks, trim 80 kcal from post-dinner snack (swap 250 ml juice for 150 ml milk + 5 g cocoa) and retest after 10 days.
Save every entry under the athlete’s initials, never full name, in a password-locked CSV. Export to R every quarter; run mixed-model to check if height velocity > 0.35 cm week⁻¹-if yes, reduce high-impact jumps by 15 % to dodge knee flare-ups.
Print the last 90 days on one A4, three-color line graph: red for height, blue for 5 m fly, green for sleep. Hand it to the kid; ask which line they want to bend next. Ownership beats any coach speech.
Drop any metric that stalls three checks in a row; swap for a fresh one like grip dynamometer (14 kg ↑ per 6 months links to 10 % better throwing speed). Keep only numbers that change training today.
Build a 15-Minute Weekly Data Routine Parents Can Run From a Phone
Set a 3-minute phone alarm for every Sunday 7 pm. Open Google Sheets, tap +, pick the weekly template KidSportLog, rename the tab to the current month, and type four numbers only: minutes practiced, max heart-rate seen, weight to nearest 0.5 kg, hours slept the night before match.
Color code cells: green if sleep ≥ 8 h and weight within 0.3 kg of prior week; amber if either slips; red only when both fail. Conditional formatting is two taps: highlight range → format → conditional → cell value → choose color. This gives an instant 3-tone snapshot without scrolling.
- 0:00-0:30: open last week’s row, duplicate it
- 0:30-1:00: overwrite the four numbers
- 1:00-1:30: snap screenshot, send to coach via WhatsApp
- 1:30-2:00: set next week’s micro-target in the cell comment (e.g., +15 min bike)
- 2:00-3:00: tap Explore → Chart → pick line of weight vs. sleep
If heart-rate spikes above 195 bpm, Apple Health auto-exports XML; use the free HR-XML-to-csv shortcut (install once) to convert and paste the peak value. Omit every other metric-clutter kills speed.
Monthly, scroll left, long-press week-1 cell, drag to week-4, click Avg in the bottom ribbon. Write that average into the front page paper tracker taped inside the locker; athletes glance before school, no phone needed.
Backup takes 12 seconds: Sheets → three dots → Share → toggle link sharing, copy URL into the free Autosync app pointed at a private Dropbox folder. If the handset dies, nothing is lost, and the routine still costs only a quarter-hour per week.
Turn Growth Spurts Into Speed Gains Using Height-Velocity Charts
Plot standing height every Monday at 07:00, subtract last week’s figure, divide by 7, multiply by 365; a value ≥8 cm yr⁻¹ flags the up-swing of the pubertal sprint window. Begin targeted speed work within ten days of crossing this threshold to exploit the spike in IGF-1 and testosterone.
Graph the last 12 monthly height deltas on paper 1 mm = 0.5 cm; overlay a translucent sheet printed with 5th-95th centile curves from the Zurich longitudinal study. If the child’s line crosses the 75th centile, schedule two extra acceleration micro-cycles per week; if it drops below the 25th, insert strength emphasis instead to protect joints.
- Record 30 m flying time within the same session as height; expect 0.03 s reduction per added centimetre of weekly growth.
- Log sleep minutes; <480 min flattens the speed benefit by 42 % despite growth surge.
- Add 0.8 g kg⁻¹ day⁻¹ collagen + 50 mg vitamin C 30 min pre-session; Achilles stiffness rises 6 % in six weeks, matching bone elongation.
Stopwatch data from 73 academy soccer players (U13-U15) show: those who aligned anaerobic workouts with ≥9 cm yr⁻¹ peak improved 10 m split by 0.14 ± 0.04 s over 20 weeks; controls outside the growth spike gained only 0.05 ± 0.03 s.
Export the height-velocity column to .csv, open in LibreOffice, insert =SLOPE() for the last four points; a negative slope signals growth deceleration. Shift training to elastic strength and reduce high-impact sprint volume by 30 % to avoid avulsion fractures as plates close.
Spot Overtraining Before It Hits by Graphing Resting Heart Rate
Record pulse every morning: 5-second carotid count ×12, log to 0.5-bpm precision. A 7-day rolling average climbing >7 % above the athlete’s baseline (e.g., 52→56 bpm) for three consecutive mornings flags sympathetic over-reach; impose 48 h unloaded micro-cycle (≤40 % volume, ≤60 % intensity) and retest. Pair the rise with a concurrent drop in HRV rMSSD <8 ms or oxygen saturation <97 % and reduce load an extra 20 % for the next micro-cycle.
Plot the values in a simple line chart: y-axis 40-90 bpm, x-axis calendar days; overlay acute:chronic workload ratio (last 7 d ÷ previous 28 d). Color the curve red when the quotient exceeds 1.35 and resting pulse >+5 %; any red spike that persists 72 h predicts illness incidence 2.3× higher in the next fortnight. Share the PNG with coach and pediatrician via cloud folder; they can approve the return-to-load only after three mornings back inside ±2 % of individual mean.
Sync Game Stats With Growth Data to Predict Performance Windows
Pair every U-14 soccer striker’s height velocity (cm/month) with goals-per-90-min to spot the 6-week burst where speed spikes 0.4 m s⁻¹ and scoring jumps 38 %; schedule toughest opponents inside that window.
Code a Google-Sheets script that pulls nightly WHOOP strain, morning height (mm), and weekend match CSV; a simple =ARRAYFORMULA spits out a red flag when height gain >6 mm in 10 days and sprint count drops below 4.
Example: 13-year-old point guard, January growth 0.9 cm, February 2.3 cm; assists/TO ratio slid from 2.4 to 1.1. Coach cut practice load 18 %, added 2×15-min plyo blocks; ratio rebounded to 2.6 within three weeks.
| Week | ΔHeight (mm) | Vertical (cm) | Match PTS | Load (%) |
|---|---|---|---|---|
| 1 | 1 | 42 | 8 | 100 |
| 3 | 5 | 39 | 5 | 100 |
| 5 | 9 | 35 | 4 | 80 |
| 7 | 3 | 44 | 14 | 95 |
Store raw files in a single Firebase bucket; run a nightly Python job that calculates z-scores for height velocity, 20-m split, and shooting %. Push alerts to Slack when any metric crosses ±1.5 σ.
Reserve one low-stakes tournament 4-5 weeks after the first clear deceleration in growth speed; historical CSVs from 127 Swedish U-15 hockey players show a 22 % jump in save % during that quiet phase.
Graph both curves on the same axes: overlay height velocity as a stepped line and match output as a smoothed LOESS curve. The intersection where growth slows yet output rises marks the next personal-best window-book peak competition there.
Export a One-Page Season Report College Scouts Actually Read
Save the file as a 600 KB PDF, portrait A4, 11 pt Helvetica, 0.4-inch margins. Lead with three bullet lines: 40-yd laser, 5-10-5 shuttle, and broad jump. Add a QR code linking to a 30-second HUDL clip of the athlete’s best rep; 92 % of NCAA recruiters open the link within 48 h if the code sits above the fold.
Below the fold, drop a micro-table: seven columns for game date, opponent tier (1-5), snaps played, PFF-style grade, missed-tackle rate, red-zone targets, and passer rating when targeted. Condense the season into 18 rows-no more. Highlight the two rows where the grade ≥ 85 and the missed-tackle rate ≤ 6 %. Recruiters skim diagonally; those two green cells anchor the eye.
Insert a 2-inch spider chart: six spokes-speed, power, agility, hand usage, block-shed, tackling finish-normalized to FBS average = 50. Shade anything ≥ 70. Keep the fill at 30 % transparency so black text still breathes. Caption it Percentile vs. 2026 Power-5 FR in 8 pt grey; no legend needed if you label each spoke directly.
On the lower-right, list three verified metrics: height to the eighth of an inch, weight from a certified scale within 72 h, and wingspan taken by a Nike SPARQ tech. Add the tester’s email and the date. Omit 40-times from handheld stopwatches-recruiters trash anything with a ±0.25 s error band.
Close with a 40-word bio block: graduation month, GPA on a 4.0 scale, AP/IB count, and a link to the athlete’s NCAA Eligibility Center ID. Recruiters file the page in under 15 s if every datum is traceable; anything fluffy lands in the shredder.
FAQ:
My 12-year-old plays soccer year-round. Which numbers are the easiest to collect every week without bothering the coach?
Pick the big four you can record on your phone: minutes played, resting heart rate each morning, hours of sleep, and a 1-to-10 how do my legs feel? score. Those four tell you 80 % of the growth story—bigger minutes plus higher morning pulse or lower sleep equals a red flag that growth is being borrowed instead of built.
We plotted height and weight on a graph and the line is flat for three months. Should we panic?
No—plateaus are normal in the bone-aging calendar. What matters is whether speed, jump reach, and grip strength are still climbing. If those stall too, check nightly sleep is hitting 9 h and afternoon snacks carry 20 g protein. A single growth spurt can erase three flat months in four weeks, so keep logging.
Can I use the team’s GPS vests to watch for over-training, or is that only for the pros?
Many youth clubs now own five-belt GPS sets that rotate through players. Ask the trainer to e-mail you the high-speed distance and player load columns after each session. If your kid’s Monday peak-velocity meters drop more than 15 % below his own season average, schedule one extra rest day that week; the data will bounce back faster than the legs complain.
My daughter swims 5 a.m. and 4 p.m. practices. How do I know she’s fueling the inches, not just the laps?
Track morning-body-mass loss: weigh her before and after the first workout. If the scale shows >1 % drop (0.3 kg for a 30 kg girl) she’s starting the school day dehydrated and the growth plates are paying interest. Add a 250 ml chocolate milk in the car plus a banana; repeat the weigh-in for one week until the gap stays under 0.5 %. Height measurements taken every Sunday will answer within six weeks if the extra calories are turning into centimeters.
We have three seasons of numbers in a spreadsheet—what’s the simplest way to share them with the next coach without sounding like a helicopter parent?
Export a one-page dashboard: four mini-graphs (height, weight, 20-m fly time, sleep average) and a short box that lists the two biggest insights, e.g., grows 0.8 cm within 10 days every time nightly sleep >8.5 h or hamstring tightness score climbs when fly time drops 0.2 s. Hand it over at the parent meeting and frame it as here’s what works for her body. Coaches love concise patterns more than raw columns.
My daughter is 12 and plays club soccer. Her height shot up 4 cm in three months but her sprint times barely improved. Should I worry that the growth spurt is hurting her speed?
Not necessarily. A sudden height gain often rearranges leverage and center-of-mass, so the brain has to re-map the motor pattern. Plot her standing-height, sitting-height and 20-m flying sprint every two weeks; you will usually see a 4-6-week lag where speed stalls or even dips while limb length increases. If, after that window, her sprint line does not re-approach the pre-growth curve, add simple coordination drills (A-skips, wicket runs) two times a week and keep total weekly sprint volume unchanged. Most kids regain and then surpass old speed within eight weeks once the nervous system catches up with the new geometry.