Youth Soccer at 13-14: Puberty, Late Bloomers and the Relative Age Effect

At 13 and 14, most kids move to full 11v11 soccer just as puberty hits, and two teammates the same age can be years apart physically. That gap favors early maturers and kids born early in the selection year, which can make a late bloomer look further behind than they really are. Your job in these years is to keep your kid playing somewhere they get minutes and confidence, because this is also when the most kids quit.

Key takeaways

• Mean age at peak height velocity is about 13.8 years in boys and 11.9 years in girls, and maturity-related differences in size and function are greatest between ages 11 and 14.
• In a study of 3,364 U.S. female youth players, players born early in the selection year were overrepresented at club and talent ID levels but not on youth national teams, which had a higher share of late maturers than any other stage.
• Bio-banding groups players by biological maturity instead of age, and players in a Premier League academy bio-banded tournament said it gave late maturers more chances to show technical and tactical skill.
• From the 2026-27 season, US Youth Soccer, AYSO and US Club Soccer form age groups on an August 1 to July 31 cycle, but U.S. Soccer says players will still be scouted by birth year.
• In the Aspen Institute's 2025-26 national survey, former players stopped playing at an average age of 12.93, and 13 was the single most common quitting age.

Why do same-age kids look so different at 13?

Kids hit their growth spurt at very different times, and the spread is widest right in this age band. A 2017 review on bio-banding by Cumming, Lloyd, Oliver, Eisenmann and Malina in the Strength and Conditioning Journal puts the mean age at peak height velocity (the fastest stretch of growth) at about 13.8 years for boys and 11.9 for girls. Early-maturing boys are on average taller, heavier, stronger, faster and more powerful, and the authors say those differences are greatest between ages 11 and 14.

The same paper says the linear growth spurt lasts about 24 to 26 months. So a boy who seems to be losing every 50-50 ball at 13 may simply not have started his spurt yet, while the kid beating him has nearly finished his.

Things you may notice during a growth spurt:

• Your kid looks clumsy or slower for a while.
• A player who dominated at U11 suddenly gets pushed off the ball.
• Coaches pick the biggest kids for certain positions.

None of that, on its own, tells you where your kid ends up. If your kid has new pain in a knee, heel or back during a growth spurt, have a doctor or athletic trainer look at it rather than guessing.

What is the relative age effect?

The relative age effect is a selection bias toward players born earlier in the selection year, who are older (and often bigger) than teammates in the same age group. U.S. Soccer's 2017 PDI FAQ (a U.S. Soccer document hosted by Florida Youth Soccer) says birth-year registration "is not intended or expected to eliminate relative age effect," because any one-year age band puts some players nearly a full year older than others.

U.S. research shows how this plays out. A 2024 study by Finnegan and colleagues in Biology of Sport looked at 3,364 U.S. female youth players from 2021-22. Players born in the first quarter of the selection year were overrepresented at club and Talent ID Center levels. On youth national teams, the birth months were spread evenly, with a lean toward fourth-quarter births and a higher share of late maturers than at any other stage.

That's one study of girls, so don't stretch it too far. But it fits what the bio-banding researchers describe: the early, bigger kids get picked first, and some of the later, smaller kids are still there at the top end.

How the 2026 age group change affects this

Starting with the 2026-27 season, US Youth Soccer, AYSO and US Club Soccer form age groups on an August 1 to July 31 cycle instead of the January to December birth year used since 2016-17. U.S. Soccer's player registration page confirms the switch, and Illinois Youth Soccer applies the same cycle here from the 2026-27 season and registration year.

Two things to understand:

• The oldest kids are now the August birthdays. Under the new cycle, a child born in early August is the oldest in the group and one born in late July is the youngest. The relative age effect doesn't go away. It just moves to different birth months.
• Scouting still uses birth year. U.S. Soccer's page says that regardless of the registration choice, players will need to be scouted based on their birth year.

U.S. Soccer also says each organization member approves the age cycle for its own leagues and competitions, and the three groups above are the ones it lists as adopting August 1 to July 31. Programs such as the Olympic Development Program (ODP) or MLS NEXT may run on different cutoffs, and we couldn't confirm their 2026-27 rules from their own published pages. If your kid plays in one of those, ask the program directly which cutoff it uses before tryouts.

What is bio-banding, and should you ask for it?

Bio-banding means grouping players by biological maturity, often by the percentage of predicted adult height they've reached, instead of by age. The Cumming et al. review explains that peak height velocity tends to happen at roughly 88% to 96% of adult height, so that percentage gives a rough sense of where a kid is in the spurt.

The research comes mostly from English academies. In a 2019 study of a Premier League academy bio-banded tournament, players reported that early maturers faced more physical and technical challenge when they played kids at their own stage, while late maturers got more chances to show their technical and tactical skill. The authors concluded bio-banding may help both groups.

Because the research is mostly from England, a U.S. club may never use the word. You can still ask questions that get at the same idea:

• Do you ever group players by size or maturity in training?
• Do you look at birth month when you evaluate players?
• Will you move a late developer up or down so they play at the right challenge level?
• How do you make sure small, skilled players aren't cut just for size?

The full 11v11 game arrives

U.S. Soccer's mandated small-sided standards stop at U12. The 2017 PDI FAQ says there were no mandates yet for U14 and older, so most teams from U13 up play the full 11v11 game on a full-size field.

Heading limits still apply at the start of this stretch. U.S. Soccer's Recognize to Recover guidelines recommend that U12 and U13 heading training be limited to 30 minutes a week, with no more than 15-20 headers per player per week, and that coaches teach proper technique. A suspected head injury still means your kid comes out until a health care professional clears them.

The bigger field means more running and more space, and it's a different game from 9v9. Give a late bloomer time to adjust before you judge them on it.

Why 13 is the quitting age

This age band is where kids walk away from sports most often. The Aspen Institute's 2025-26 national youth sports survey, which surveyed 3,827 kids ages 10 to 17 between October and December 2025, found former players stopped at an average age of 12.93 (12.4 for boys, 13.30 for girls). Of the kids who quit, 11% stopped at 12, 13% at 13 and 10% at 14.

The reasons line up with everything above. The top dislike former players named was feeling "I'm not good enough" (29%), followed by bad coaching (21%). And 21% of former players said they'd been pressured by parents to play when they didn't want to, compared with 9% of current players.

A late maturer sitting on the bench of a top team is exactly the kid who starts feeling "not good enough." Often the better move is a team where they play real minutes, even if the badge is less impressive. Our guide on youth soccer burnout and why kids quit goes deeper on this, and if your kid is also playing two or three sports, read our piece on early specialization vs. multi-sport.

What this means for your family

• Measure your kid against their own progress, not against the biggest player on the field.
• If your kid is small or born late in the selection year, don't treat a cut or a bench role as a ceiling.
• Ask clubs how they handle maturation and birth month, even if they don't bio-band.
• Pick the team where your kid gets minutes and confidence over the one with the bigger name.
• Watch for pain during growth spurts and see a doctor or athletic trainer if it lingers.
• Check that heading practice at U13 stays within 30 minutes and 15-20 headers a week.
• For 2026-27 tryouts, confirm the age cutoff with your specific league or program, especially ODP or MLS NEXT.
• Keep pressure off. If your kid wants a break, listen before you push.

Up next: high school

After 14, high school soccer enters the picture, and in Illinois that brings its own rules about club play during the school season. Our guide to high school vs. club soccer for ages 15-19 covers that decision. If you're still sorting out the earlier years for a younger sibling, start with ages 9 to 12.