- What is Peak Height Velocity (PHV)?
- What happens during PHV?
- Why is PHV important?
- How to calculate age of PHV?
- What do I do once I know the age of PHV?
1. What is Peak Height Velocity (PHV)?
Peak height velocity (PHV) is a period in childhood where maximum rate of growth occurs. It is otherwise known as the Growth Spurt. It indicates hormonal, physiological and anatomical changes in the body bringing a child into adolescence. Although children may have a few smaller secondary growth spurts, PHV usually occurs as a single event. This usually takes place few years earlier in girls (10-12 years old) than boys (12-14 years old). Peak growth can last anything from a few weeks to a few months.
2. What happens during PHV?
Prior to puberty, boys and girls develop at a similar rate. Around and during PHV, there are significant changes occurring in the body.
- Hormonal. Oestrogen and Progesterone are released from the ovaries in girls with the onset of menarche usually around the same time. For boys, the testes release testosterone (usually at a slightly later age).
- Sexual characteristics. As a consequence of hormonal change during the time of PHV, girls will experience breast enlargement, a widening of the pelvis and hair growth. Boys will experience a dropping of the voice, growth of body and facial hair and increase muscle mass and strength.
- Growth. During PHV, the bone growth plates in become very active producing new cells. Height rapidly increases along with muscle mass and weight.
- Physical characteristics. The physical capabilities of boys and girls rapidly change, with increases in strength, speed, agility and endurance. Boys generally have more dramatic increases in strength due to higher testosterone levels, but often remain less flexible than girls.
3. Why is PHV important?
With rapid rates of change occurring, the adolescent body may now respond differently to exercise with higher energy requirements. This may affect the body in various ways.
- Increase energy demands. With such rapid growth, energy demands in the body increase substantially. It is important to make sure children have a high calorie intake with a good variety of macro and micronutrients intake.
- Increase risk of injury. As growth plates become more active in PHV, they become more prone to injury. This can occur via an acute injury or chronic overuse. Common examples of growth plate injuries include Osgood-Schlatter’s (knee) and Sever’s pain (heel). Reducing excessive high impact loading (e.g., jumping, running, football) during PHV can help prevent this.
- Enhancing physical gains. Although growth plates may need time to rest and recover during PHV, adolescents can make the most of the hormonal surges to increase strength, endurance and flexibility of muscle and tendons. This requires the right kind of strength and conditioning training and exercise.
4. How to calculate age of PHV?
By plotting height over a period of time, it is possible to calculate PHV. However, simple toolkits are available that use statistical models to predict this for us with just a few simple measurements. The closer a child is to PHV the more accurate the prediction. Therefore, the ideal age of prediction is 9 to 13 years in females and 12 to 16 years in males.
To calculate your PHV, you will need to know your child’s;
- Date of Birth
- Date of Measurement
- Standing Height (cm)
- Sitting Height (cm)
- Weight (with minimal clothing) (kg)
Once you have recorded the above, put the figures into the online calculator created by the University of Saskatchewan to calculate your child’s PHV.
5. What do I do once I know the age of PHV?
Once you know your child’s PHV, have a think about the following questions regarding their exercise and lifestyle.
- Is there excessive high impact training or sport during PHV? It is important to reduce the amount of intense exercise/training children are exposed to during PHV. This may sometimes be difficult with multiple school or club commitments. Have a discussion with school/club/teachers/coaches if this is the case.
- Are they doing enough Strength and Conditioning training? PHV is a great time for children to learn and become more familiar with the principles of Strength and Conditioning training, as well as trying new exercises such as yoga, Pilates, weightlifting and other gym activities. We want to maximise the short “hormonal window” available during the PHV to maximise strength and endurance gain.
- Do they have enough variety in their exercise and training? Children spending all their time focusing on a single sport (e.g., football, hockey) before the age to 12, are likely not to have enough variety in their exercise programmes. Research shows that children under the age of 12 who have a variety of sporting endeavors are likely to enhance their co-ordination skills, endurance and strength.
- Do they have enough rest days in their diary? Children often have jam packed schedules with school, sport and activities, not to mention social commitments! Making sure children have enough time to rest, recover and growth is essential, especially during the growth spurt.
- Do they eat enough of the right foods? During growth spurts, calorie requirements are huge. A balanced diet rich in macronutrients, protein calcium is essential to make sure children have the correct fuel and energy intake to grow. Calorie requirements and be estimated and planned for accordingly during PHV. Children should not be dieting or calorie restriction during this time unless there are specific medical needs.
- Do they sleep enough? Like adults, rate of growth, repair and recovery is highest when children sleep. Sleep requirements may also increase during PHV so ensuring they have adequate lifestyle habits and routines to encourage good quality and quantity sleep is essential. It is important to try and educate them around the importance of sleep hygiene and any potential distracting factors e.g. screen time, social interactions.
If you have any concerns with your child’s growth, development or injuries please get in touch with the LBSM team to speak to one of our doctors.