Two words that get used interchangeably, and shouldn't
Growth describes measurable change in size: height, mass, limb length, tissue dimensions. It is quantitative. You can put a number on it with a tape measure and a set of scales.
Maturation describes progress towards the mature adult state - how far along the journey a child is, and how quickly they are travelling. It is qualitative as well as quantitative, it varies between body systems, and every child ends up in roughly the same place at a different time and at a different rate.
A useful way to hold the distinction: growth tells you how big the athlete is today, maturation tells you how much of their development is still to come. Two athletes standing at exactly the same height can be at opposite ends of that spectrum.
Growth, how much
- Standing height, sitting height, leg length
- Body mass and lean mass
- Measured with a tape and scales, monthly
- Expressed in cm per year (growth velocity)
Maturation, how far along
- Skeletal age, sexual maturity, percentage of predicted adult height
- Timing (when it happens) and tempo (how fast)
- Estimated, not measured precisely, in most settings
- Explains why same-age athletes differ so much
Growth and maturation answer different questions about the same athlete.
Timing, tempo and status
Three terms do most of the heavy lifting in the research literature. Maturity status is where a child is right now - for example, pre-pubertal or mid-pubertal. Maturity timing is when landmark events happen, such as an early or late growth spurt. Maturity tempo is how fast the child moves through the process once it starts.
An early-maturing athlete with a slow tempo and a late-maturing athlete with a fast tempo can cross paths at 14 and end up at similar adult heights, having had entirely different experiences of youth sport along the way.
- Status: where the athlete is today.
- Timing: whether they started earlier or later than peers.
- Tempo: how quickly they progress once it begins.
- Adult outcome: largely genetic, and poorly predicted by any single measurement in childhood.
How maturity is estimated in practice
The reference standard is skeletal age from a hand-wrist X-ray, which is not appropriate for routine sport screening. In practice, clubs use simpler proxies that are good enough to guide decisions rather than to make diagnoses.
The most common is percentage of predicted adult height, calculated from the athlete's height, weight and mid-parental height. Another is maturity offset, an estimate of how many years an athlete is from their peak growth rate. Both carry meaningful error at the individual level, which is exactly why they should inform conversations rather than dictate selection.
| Method | What it tells you | Practical for clubs? |
|---|---|---|
| Skeletal age (X-ray) | The most accurate maturity status | No, clinical use only |
| % of predicted adult height | How much growth is still to come | Yes - needs height, weight, parent heights |
| Maturity offset | Estimated years from peak growth | Yes, least accurate around the spurt |
| Serial height tracking | Growth velocity in cm/year, in real time | Yes, the single most useful habit |
Estimates guide decisions. They are not measurements of talent or potential.
Why it matters for selection
In any single birth-year cohort, the biggest, strongest, fastest players are disproportionately those born early in the selection year and those maturing early. They are picked more often, coached more often, and given more competitive minutes, a compounding advantage that has nothing to do with long-term potential.
The consequence is well documented. Late maturers are systematically under-selected in adolescence, despite often possessing better movement skill, and are more likely to drop out before their physical development catches up. Programmes that keep late maturers in the system frequently find they are the ones who progress furthest as adults.
Why it matters for injury
Growth-related conditions - Osgood-Schlatter, Sever's disease, Sinding-Larsen-Johansson, adolescent patellofemoral pain and growth-related back pain, cluster around the fastest phase of growth rather than a particular birthday. During that window, bone lengthens ahead of the soft tissue that attaches to it, tendon attachment sites are less tolerant of repeated pull, and coordination temporarily degrades because limb lengths have changed faster than motor control can update.
This is why age-banded training rules miss the point. A squad of 13-year-olds contains athletes who finished their spurt a year ago and athletes who have not started, with completely different tolerance for jumping, sprinting and volume in the same session.
The practical implication
Load decisions should follow maturity and symptoms, not birth year. During a rapid growth phase, hold total volume steady, keep strength work in, and reduce high-impact repetition rather than removing training altogether.
What parents and coaches can actually do
- Measure standing height every month and record it, a jump of 2cm or more in a month signals a rapid phase.
- Ask about growth in the same conversation as training load and soreness.
- Expect coordination, jumping and sprint mechanics to dip temporarily during a spurt.
- Judge progress against the athlete's own trajectory rather than against the biggest player in the squad.
- Keep late maturers in strong training environments long enough for their development to arrive.
The honest caveat
Maturity estimates from height and parental data carry error margins of around a year in either direction, and no method predicts adult performance reliably. The value is not in the precision of the number, it is in the change of mindset. Once a coach accepts that a squad of same-age athletes is biologically diverse, decisions about volume, impact, expectation and selection all improve, whether or not the estimate is exactly right.