Why nutrition matters for teen athletes: Growth, fuelling and injury prevention

Adolescence is a critical time for growth, development and the establishment of lifelong

health behaviours. For teen athletes, the nutritional stakes are even higher. The demands of sport, combined with the biological processes of puberty, mean that energy and nutrient needs skyrocket. When nutrition doesn't keep up, performance can suffer — and so can health.

What is adolescence?

Adolescence is defined as the transition from childhood to adulthood, typically spanning the ages of 10 to 19 years. It includes three stages:

1. Early adolescence (10–13 years),

2. Middle adolescence (14–16 years), and

3. Late adolescence (17–19 years).

This period is marked by rapid physical, hormonal and cognitive changes, including key growth spurts.

Key growth periods and sex differences

One of the most important milestones during adolescence is the peak height velocity (PHV) — the fastest rate of growth in stature (height). Timing of PHV varies between individuals, but is typically:

• Girls: Earlier, between ages 10–12.

• Boys: Later and more pronounced, 13–15 years.

During PHV, adolescents can gain up to 8–10 cm in height per year and accrue significant increases in lean mass and bone mineral content — all of which require extra energy, protein, and key micronutrients like calcium and vitamin D.

Increased energy and nutrient needs

Nutrition needs during adolescence are higher than at any other stage of life (except

pregnancy), particularly for athletes. Energy requirements can increase by up to 20–30%

above those of non-athletes to support both training demands and growth.

Key nutrients of concern include:

• Calcium and vitamin D: Essential for bone development.

• Iron: Crucial for oxygen transport, especially in menstruating girls.

• Protein: Needed for muscle growth and tissue repair.

• Carbohydrates: To fuel activity and support brain function.

Consequences of inadequate nutrition

Failing to meet nutritional needs can impair growth, delay puberty, and increase the risk of injury. One of the most common consequences is bone stress injury (BSI), particularly in endurance and aesthetic sports.

What are bone stress injuries (BSIs) and how does nutrition play a role?

BSIs are overuse injuries caused by repetitive loading of the skeleton without adequate time or resources for bone repair and adaptation. They exist on a continuum — from stress reactions to stress fractures — and are especially concerning during adolescence when the skeleton is rapidly growing but not yet fully mineralised.

It is very common in our clinic to see adolescent athletes who’s diagnosis of BSI coincides with peak height velocity (PHV).

Adolescents experience a higher incidence of BSI compared to adults, with up to 35% of

injuries in adolescent runners being stress-related. Sports with higher prevalence include:

• Running and athletics

• Dance and gymnastics

• Swimming and rowing (often due to low-impact loading plus energy deficits)

Risk factors for BSI in teen athletes

The development of BSI is influenced by many factors but when it comes to nutrition, low energy availability (LEA) and inadequate Calcium & Vitamin D are the most common.

• Low energy availability (LEA)

LEA occurs when energy intake is insufficient to support both training and physiological

functions. Think of an athlete’s body like an iPhone; when the battery is low, it goes into low power mode which disables certain features to conserve energy. This is the same as if an athlete doesn’t consume enough energy, body functions such as bone growth and repair, slow down.

In adolescents, LEA is particularly common around PHV as there is a substantial increase in energy expenditure (due to growth) but often no increase in energy intake to match. LEA can also occur with sudden increases in training load or if athletes are intentionally restricting intake to manipulate body weight.

• Calcium and vitamin D

Both calcium and vitamin D play vital roles in bone mineralisation:

1. Calcium provides the structural material for bones.

2. Vitamin D supports calcium absorption and bone metabolism.

   
   

The best sources of calcium are milk, yoghurt & cheese but despite what many are led to believe, plant-based sources such as spinach and almonds are very poor sources in

comparison. Due to diet trends and misinformation, exclusion of dairy is common in

adolescents which has resulted in more than 70% of adolescent females and more than 50% of adolescent males not meeting daily calcium requirements.

Adequate Vitamin D relies on appropriate sun exposure, so during winter or indoor sports, exposure can be limited. Close to a quarter of all adolescents have low Vitamin D levels.

Inadequate intake and exposure during adolescence — when up to 90% of peak bone mass is accrued — can reduce bone density and increase BSI risk.

Take-home messages for teen athletes and parents

• Adolescents go through rapid growth, especially during PHV, with boys and girls

experiencing different timing and magnitude of growth.

• Energy and nutrient needs are significantly increased, particularly for athletes.

• Inadequate energy and nutrient intake can impair growth and increase the risk of

bone stress injury.

• Key risk factors include low energy availability and insufficient calcium & vitamin D.

• Sports with high rates of BSI include running, gymnastics, dance, and swimming.

• Prioritising a balanced, energy-sufficient diet with adequate bone nutrients is

essential to support performance, health and injury prevention.

• Seeing a Sports Dietitian for individualised advice during key periods of growth is

important for ensuring adolescent athletes meet their high energy requirements. In

addition, a Sports Dietitian can help overcome barriers to adequate intake such as

limited food preferences and low appetite.

This is Sports Dietitian Dr Rebecca Haslam, signing off for now!

You can book an appointment with Rebecca or Belle at www.upnadamptphysio.com (booking button at the top of the homepage)

Bookings also available on our website for:

• VO2 Testing - to optimise your training

• Physiotherapy - to treat acute or chronic injuries

• Run Specific Strength Programs - contact us via the website or email us at upnadamptphysio@gmail.com

• Remedial Massage - to relieve accumulative muscle tightness from training & racing that could lead to injury.