What if we could use the awkward period of puberty to our advantage?
I think puberty & maturation is an area of hitting development that is often overlooked. I won’t bore you w/ the details on how this thought experiment (more accurately, an observation & discussion) developed. Let’s just skip that part & get right into it by going back to biology class w/ a refresher on puberty. Specifically, were going to look at growth velocity, visual development, & brain development. This post is going to mainly focus on male athletes as that has been the majority of my coaching experience.
Defining the Moving Target
I want to clearly define what I am talking about. It will make things easier as you read on. According to the National Institute of Child Health & Human Development, puberty for boys generally starts from the range of 9-14 years old. While puberty doesn’t have an exact starting date, it does have a range that we should expect to see signs that maturation in athletes have begun. Most males will finish their physical development around the ages of 16-18 years old, but some males can continue to grow into their early 20s. The expectation for the length of puberty can vary from 2-5 years. This is based off of US & European populations. This age range & duration is going to be heavily influenced by the genetics & nutrition of the athlete. The body needs to know it has enough energy reserves to start the process & continue it to full maturation.
Now that we defined the age range lets look at growth & growth velocity. One of the things that makes it so hard to coach players in their adolescence is the body they start with from year to year could be drastically different. When children are younger their growth velocity for height averages 5-6cm per year. For most males 13.5 is when the peak height velocity occurs & they can grow on average 7-10cm a year. Then the growth velocity starts to taper down around 16-18 years old at a rate of 1-2cm a year. Around 19-20 growth velocity tends to stop, but again genetics & nutrition are going to play large factors. Males can expect to gain 13-20lbs of body mass a year during peak height velocity w/ around 50% being muscle. Growth plates in the bones will close up near the end of puberty, its a common sign associated w/ the end of the maturation process.
Why Is It a Moving Target?
In reading through all this I didn’t realize that there is a typical pattern to how the body parts grow. First, the feet & hands grow often 1-2 years before peak height velocity. Which in my experience teaching middle school makes sense because you tend to see boys who look big-footed & clumsy at that age. Next the lower legs, specifically the tibia & femur. This is an extremely awkward stage as stride length, balance, & posture all have to be re-learned. Then the torso & spine really get going during the peak height velocity window of 12-14. Finally, the arms grow last & the shoulders expand after. So not only is the young athlete going through an awkward growth period, but all the body parts are growing at different times. Following the timeline we could speculate the feet & hands to grow around age 11. Then the lower legs at 12, followed by the torso & spine at 13 or 14. Finishing off w/ the arms & shoulders at ages 15-17 respectively. Puberty also comes w/ a “strength spurt”. Peak strength velocity for most strength metrics being 1.5 years before peak height velocity & peak around 1 year after peak height velocity. (Roughly from 12-15) When the athlete begins to grow accustom to their new body dimensions, they can start to apply greater amounts of force.
To complicate things, the athletes visual system is still in the process of developing & having to recalibrate. Interpupillary distance (how far apart your eyes are) grows most significantly before age 12. After that the athlete might see a total growth of 3-4mm during adoloscence as their face & skull continue to develop. Why does this matter? As the angle of vision between your two eyes changes it will also change your depth perception, visuospatial awareness, & your convergeance/divergence abilities. Not to mention the athletes eyes are going to be at a different distance from the task because of the added body growth. Growing taller means the eyes move further away from the ball at contact. In short, hitting a baseball might be more difficult for a time because the athlete’s mental maps & spatial awareness is out of date. The good news is a lot of the brain’s visual systems start to improve, but they are fairly new & need time to develop. So stressing the visual systems can be beneficial, but it also needs to come w/ a side of patience. Faster neural transmission begins, improved inhibitory control, improved visual acuity & contrast sensitivity, smooth pursuits, saccades, & predictive tracking also all get a major development kick during this age. These are all skills that need developing & will need constant recalibrating.
Brain development takes another step during puberty. Synaptic pruning intensifies significantly during puberty. Essentially “use it or lose it”, the brain starts trying to eliminate weaker neural connections & strengthening the most frequently used ones. Myelination starts increasing & neural processing speeds improve, improving reaction times & visual processing speeds. The limbic system matures earlier than the prefrontal cortex. Why is this significant? The limbic system is responsible for regulating emotion. Before the hitter can process the information logically in the prefrontal cortex, it has to run through the limbic system & the input gets assigned an emotion. Since the prefrontal cortex doesn’t fully mature until the mid to late 20’s, the limbic system can create an imbalance in emotions or stress responses during puberty. All of which can alter performance. The brain has to constantly update its internal models for limb length, inertia, & new body positioning during this time period. During peak height velocity, the internal model becomes the most unstable due to the rapid growth. Puberty isn’t just a growth period, it’s a full neurological rewiring. All of which can cause periods of inconsistent performance.
Practical Applications
I’ll start w/ this, “PATIENCE”. Remember if you’re a professional coach, (let’s assume you’re 35) then you have had at least 10 years to calibrate your movements to a stable body. An athlete going through puberty barely mastered walking 10 years prior & is still trying to calibrate to an ever changing landscape. So yelling your instructions louder isn’t going to improve the outcome. In my experience in working with this age group, bad swings are usually the byproduct of the athlete not being able to manipulate the weight of their own body. This typically either stems from being physically weak or hitting from a poor, unathletic setup. Recommendations I’ve read & put into practice when I coached high school-age athletes seemed very practical. First, scale out the workout program accordingly. Injury incidence increases during high-intensity training while in the middle of peak height velocity. The bone may have grown faster than the muscles & tendons had time to adapt. So doing “Hell Week” is a dumb idea, especially when there is no tapering of the workload. Start simple; have athletes demonstrate they can manipulate & move their own body weight. Preferably in a variety of movements (e.g., Pushups, Pullups, Lunges, Box Jumps, Body Weight Squats). This is why playing multiple sports at a young age is so beneficial. Spend a little bit of time every day coordinating their balance. Remember, the athlete needs constant recalibration of their body. There are plenty of ways to accomplish this without me going into detail. As I progressed in my coaching career at the high school level, we developed competencies. If you couldn’t demonstrate the body weight competency, you couldn’t do any of the lifts. If you couldn’t pass the force output tests in the weight room, then you couldn’t move from basic arm care to velo training. This was how you differentiate the development plan, so no athletes could progress unnecessarily above their current skill level.
Theoretical Applications
Going into a full thought experiment now, I think we could really take advantage of the neural plasticity peak during adolescence. Especially on the visual/perceptual side. Implementing full daily vestibular activation routines in my opinion would calibrate internal models for movements faster. Plus from experience they are really quick & easy to integrate into a warmup routine. Take advantage of the increased growth & train the visual & visual decision making skills specific to baseball. Could we push them to levels never before imagined? With the resiliency & adaptation ability of the human body I think there’s a lot to gain by taking advantage of one of the best developmental periods in the athlete.
The other caveat to this would be adapting talent identification criteria based on the athletes current maturity status. This would help mitigate the possibility of over-valuing early bloomers & missing out on the late-bloomers. The next step would be scaling out talent markers or predictors based on where the athlete is in their stage of puberty. Would we find any commonalities? Red Flags? There are simple ways to test that can be done, but large scale implementation could be a hurdle. First is an X-ray of the hand & wrist to compare the bone maturity, also known as a Bone Age Study. This can help determine the stage of puberty the athlete is in & can help predict their final height. Imagine being able to tailor workout programs in accordance w/ the maturation stage of the athlete. I think it could have implications in injury prevention & possibilities in talent identification & forecasting. The hurdle isn’t the X-ray, which takes 2-3 minutes. It’s the time it takes for a radiologist to read it, which is typically about 24 hours. A process that could most likely be improved. The other test is a simple blood test, which might be more problematic & invasive. However, if scaling out at the professional level the org will already have access to this.
My speculation for how this could have the largest impact would be at the international level. International players are signed right in the middle of adolescence in most cases. Factor in peak height velocities varying so much across Latin America, it would be advantageous to know the developmental timeline of the athlete. Finally, it could have a lasting impact on how international players are evaluated.
Citations
🧬 1. Growth, Peak Height Velocity (PHV), & Pubertal Growth Patterns
Malina et al. (2004).
Growth and maturation of children and adolescents: relevance to athletic performance.
British Journal of Sports Medicine.
https://pubmed.ncbi.nlm.nih.gov/14933995/
Sherar et al. (2007).
Age at peak height velocity and the implications for athletic training.
Canadian Journal of Applied Physiology.
https://pubmed.ncbi.nlm.nih.gov/17571056/
Yoon et al. (2021).
Estimating peak height velocity using the SITAR model in Korean boys and girls.
Annals of Pediatric Endocrinology & Metabolism.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8077132/
Rogol, Clark & Roemmich (2000).
Growth and pubertal development in children and adolescents.
Pediatrics.
https://pubmed.ncbi.nlm.nih.gov/10920150/
🦵 2. Limb-Segment Growth & Body-Geometry Changes
Attallah (2019).
Longitudinal growth of body segments using photogrammetry.
American Journal of Human Biology.
https://pubmed.ncbi.nlm.nih.gov/31124267/
Cameron, Tanner & Whitehouse (1982).
The adolescent growth spurt in limb segments.
Annals of Human Biology.
https://pubmed.ncbi.nlm.nih.gov/7137211/
Preece & Baines (1978).
A new mathematical model for human growth curves (Preece–Baines model).
Annals of Human Biology.
https://pubmed.ncbi.nlm.nih.gov/737449/
🌎 3. Puberty Timing in Latin American Populations
Feibelmann et al. (2020).
Puberty in Brazilian schoolboys: onset and anthropometric characteristics.
Revista Paulista de Pediatria.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7545906/
Correa-Rodríguez et al. (2022).
Estimation of pubertal growth-spurt parameters in Colombian children and adolescents.
Journal of Clinical Medicine.
https://www.mdpi.com/2077-0383/11/13/3847
Santos et al. (2019).
Growth velocity curves and pubertal spurt parameters in Peruvian children at different altitudes.
American Journal of Human Biology.
https://pubmed.ncbi.nlm.nih.gov/31188487/
Flores et al. (2024).
Growth in height and its association with overweight and obesity in Mexican children.
Frontiers in Public Health.
https://www.frontiersin.org/articles/10.3389/fpubh.2022.967146/full
Flores et al. (2024).
Height growth of Mexican boys by geographic region.
Journal of Biosocial Science.
https://pubmed.ncbi.nlm.nih.gov/37214603/
Marván et al. (2020).
Secular trends in age at menarche in 20th-century Mexico.
American Journal of Human Biology.
https://pubmed.ncbi.nlm.nih.gov/32052905/
Torres et al. (2024).
Decline in pubertal timing and relationship with excess weight in Argentinian girls.
American Journal of Human Biology.
https://pubmed.ncbi.nlm.nih.gov/37691088/
Orden et al. (2011).
Age at menarche in urban Argentinian girls and socioeconomic factors.
Annals of Human Biology.
https://pubmed.ncbi.nlm.nih.gov/21745058/
🧠 4. Brain Development During Puberty
Huttenlocher (1979).
Synaptic density changes in human frontal cortex across development.
https://pubmed.ncbi.nlm.nih.gov/117072/ (early foundational study)
Petanjek et al. (2011).
Prolonged synaptic pruning in human prefrontal cortex.
PNAS.
https://pubmed.ncbi.nlm.nih.gov/22084172/
Paus et al. (1999).
Structural maturation of the adolescent brain through myelination.
https://pubmed.ncbi.nlm.nih.gov/10591203/
Giedd et al. (1999).
Brain development during childhood and adolescence via MRI.
https://pubmed.ncbi.nlm.nih.gov/10591234/
Casey, Tottenham & Cohen (2005).
Adolescent brain development: frontal–limbic imbalance.
https://pubmed.ncbi.nlm.nih.gov/15738603/
Luna et al. (2010).
Development of cognitive control during adolescence.
https://pubmed.ncbi.nlm.nih.gov/20161308/
Somerville et al. (2010).
Heightened reward system responsivity in adolescence.
https://pubmed.ncbi.nlm.nih.gov/20173768/
👁️ 5. Visual System Development During Adolescence
Atkinson (2000).
Visual development from birth to adolescence.
https://pubmed.ncbi.nlm.nih.gov/11069860/
Leat & Gargon (1996).
Adolescent contrast sensitivity development.
https://pubmed.ncbi.nlm.nih.gov/8796097/
Bradley & Freeman (1982).
Contrast sensitivity improvements in adolescence.
https://pubmed.ncbi.nlm.nih.gov/7162404/
Simons (1981).
Development of stereopsis in children & adolescents.
https://pubmed.ncbi.nlm.nih.gov/7253858/
Birch (2013).
Binocular vision and depth development.
https://pubmed.ncbi.nlm.nih.gov/24063717/
Giaschi et al. (2015).
Development of motion perception and stereopsis.
https://pubmed.ncbi.nlm.nih.gov/25966670/
Irving et al. (2006).
Development of oculomotor function in children.
https://pubmed.ncbi.nlm.nih.gov/16580235/
Luna et al. (2008).
Development of eye movement control & visual attention.
https://pubmed.ncbi.nlm.nih.gov/18591471/
Bogfjellmo et al. (2017).
Motion sensitivity development in adolescence.
https://pubmed.ncbi.nlm.nih.gov/28275160/
🦴 6. Injury Risk, Growth, & Training Load During Adolescence
Myer et al. (2013).
How young is too young to start training? Integrative Neuromuscular Training (INT).
https://www.towsonsportsmedicine.com/wp-content/uploads/Myer-2013-HFJ-How-young-is-too-Young-to-Start-Trainng.pdf
Lloyd & Oliver (2012).
Strength & conditioning for youth athletes: position statement.
https://pubmed.ncbi.nlm.nih.gov/22544659/
Jones et al. (2024).
Youth Athlete Development – training load, specialization, maturation.
https://www.researchgate.net/publication/395422535_Youth_Athlete_Development_Critical_Insights_on_Training_Testing_and_Specialization_Pathways
Read et al. (2023).
Growth & maturation effects on injury risk in youth athletes: scoping review.
https://pmc.ncbi.nlm.nih.gov/articles/PMC11420720/
Mersmann et al. (2023).
Injury mechanisms during adolescent growth (bone–tendon asynchrony).
https://www.mdpi.com/2076-3417/14/22/10632
POSNA (2021).
Youth athlete injuries and growth plate vulnerability.
https://jposna.org/index.php/jposna/article/view/462/655
👟 7. Vision, Motor Control, and Coordination Changes
Gasser et al. (2010).
Development of postural control & temporary regression during puberty.
https://pubmed.ncbi.nlm.nih.gov/20577781/
Payne et al. (2014).
Development of visuomotor coordination & puberty effects.
https://pubmed.ncbi.nlm.nih.gov/24934192/
Mirzajani et al. (2019).
Body schema changes and motor recalibration in adolescence.
https://pubmed.ncbi.nlm.nih.gov/31579219/
🧿 8. Interpupillary Distance (IPD) Development
Evereklioglu et al. (2002).
Normal values of interpupillary distance in Turkish children and adults.
https://pubmed.ncbi.nlm.nih.gov/12062278/
MacLachlan & Howland (2002).
Normal pupillary distance in children & adults.
https://pubmed.ncbi.nlm.nih.gov/12177613/
Dodgson (2004).
Ocular anthropometry & PD ranges in childhood.
https://pubmed.ncbi.nlm.nih.gov/15314590/
Baseball Thought Experiments 