What changes at puberty
Puberty in girls typically starts one to two years earlier than in boys, with peak height velocity around 11–12 years. Oestrogen drives changes in body composition, bone development and the distribution of body mass, alongside the growth in height.
Unlike the testosterone-driven changes in boys, these do not automatically bring a large increase in muscle mass and force production. That is the core performance issue: the demands of controlling the body increase while the strength available to do so does not rise proportionally on its own.
What that means on the pitch
- Relative strength, force per kilogram, often dips through this period.
- Jumping, sprinting and change of direction may plateau or temporarily regress.
- Landing control deteriorates, contributing to knee injury risk.
- Confidence can fall alongside performance, particularly if nobody explains why.
Why strength training matters more, not less
Structured resistance training is the intervention that restores power-to-weight through puberty. Young female athletes respond strongly to it, with substantial improvements in strength, jump and sprint performance, and reductions in injury risk.
Two sessions a week, sustained through the pubertal years, is enough to change the trajectory - and this is precisely the period when many girls are offered less physical preparation, not more.
Bone health during this window
The majority of adult bone mass is laid down during adolescence, and impact and resistance training in these years has a lasting effect on bone density. Adequate energy, calcium and vitamin D intake is essential for that to happen.
Under-fuelling during this window has consequences well beyond the season, which is why energy availability sits alongside training in any serious approach to female athlete development.
The dropout problem
- Participation in girls' sport falls sharply in the early teenage years.
- Common contributors include kit and body image concerns, periods and lack of support around them, reduced enjoyment, and performance frustration.
- Open conversation about menstrual health, appropriate facilities, and coaches who explain what is happening physically all reduce dropout.
Practical guidance for this period
- Introduce or maintain two strength sessions a week from around 10–11.
- Expect and explain a temporary dip in coordination and performance.
- Track height monthly and hold volume steady through rapid growth.
- Prioritise landing and deceleration training with coaching feedback.
- Normalise conversations about periods, fuelling and sleep.
- Judge the year on development and enjoyment rather than results.