Getting a handle on a young performer’s present status from a developmental perspective is crucial. After all, without this information we have no real frame of reference for making judgements or deciding on the best way forward. The reason that talent identification policy and development pathways at junior level frequently go awry in practice (as we noted in a previous post) is in large part due to a failure to account for maturation and relative age effects. Young performers at age-grade level are far from a homogenous group. Kids in the same age group may be at very different points in their trajectory. That growth and development curves for young performers can vary so widely inevitably thwarts any attempt to adopt a blanket approach. Whilst individual growth curves eventually converge, during their formative teenage years young performers can differ dramatically in how they present at any given time and this is manifested both physically and in the performance capabilities that they exhibit. Given that much of the variability we see at age-grade is simply due to the fact that kids are at very different stages in their relative stage of development, it follows we need some way to assess where a young performer is on their individual growth trajectory. Aside from the addressing the challenge of parsing genuine ‘talent’ versus maturation effects for sporting organisations, we equally need to be able to evaluate these factors on an individual level to inform decisions on how to best support the young performer. In this post we present a tool to estimate biological age and relative stage of maturation and describe how to use this information to inform the priority areas for development and guide training for the young performer.
ESTABLISHING BIOLOGICAL AGE AND STAGE…
One of the practical challenges for evaluating biological age and stage of maturation for young performers in the field is that established assessment methods involve the use of medical scans to assess skeletal age or invasive quasi medical examination (known as Tanner staging), each of which have both logistical and ethical issues.
The alternative presented here simply involves measuring height in standing and seated positions and body mass, along with chronological age (date of birth). As such, it is far more practical as it requires minimal equipment and takes very little time, which also makes it far more feasible to undertake repeated measurement at regular intervals to refine the estimate.
BROAD BRUSH STROKES…
Before we present the tool, an important caveat is that this is a field assessment which provides an estimation: we are talking about a general guide rather than a precision instrument. The suggested way to implement this information is to provide a broad indication of what ballpark we are in to guide training priorities.
Equally it is important we acknowledge the limits of confidence in the estimate, particularly as it relates to different populations. The regression equations that the tool employs were originally derived from a sample population with particular set of demographics. As such, whilst it has been validated with other populations it naturally fares best with individuals who share similar demographics to the original group. Consequently there is a need to exercise caution and perhaps add an asterix when applying this tool with kids of different ethnicity to the predominantly white European kids who featured in the original sample.
The precision of this estimate can also vary according to the age of the young performer and how far away they are from their adolescent growth spurt (termed age at Peak Height Velocity). This can however be mitigated by repeating the assessment at regular intervals, so that we are not relying on a single snap shot.
HOW TO USE THE TOOL…
The assessment takes very little time: we simply require the performer’s date of birth as well as body mass (in kilograms) and measurements of height (in centimetres) both in standing and in a seated position. If using a stadiometer, the seated measurement is taken with the athlete sitting up tall on top of a box with their back against a wall and the height of the box is then deducted (i.e. seated height measured from the floor minus the height of the box they are sitting on). If using a tape measure, the set up is the same (sitting tall with back against a wall) and the distance from the top of the box to top of the athlete’s head is measured. Alternatively, the assessment may be performed with the athlete sitting on the floor, although it is important that they are able to sit up tall in that position with hips, shoulders and back of the head flush against the wall.
Once you have entered the relevant dates and athlete’s details (including whether they are male or female), and filled in the relevant body mass and the two height measurements, the results will be displayed automatically. Just click here or on the image below to navigate to the online assessment tool.
HOW DO WE APPLY THIS INFORMATION IN PRACTICE…
Bio-banding is a practice that is growing in popularity as an alternative way to organise competition at youth level. Assigning kids to competition grades by biological age is becoming more common, notably in junior (soccer) football leagues in Europe. Rather than using chronological age-grades, the bio-banding classification groups players based on relative stage of maturation. Age at peak height velocity (PHV), i.e. the age at which the individual hits their adolescent growth spurt, is the reference that is used to group kids and categorise the tiers of junior competition in a way that corrects for individual growth curves.
We can employ this general approach to stratify young performers into three broad bands that align with the major phases of development. The three stages are pre-adolescence (Pre PHV), the interval following onset of puberty (Mid PHV) and the later phase that follows the adolescent growth spurt, termed post peak height velocity or post PHV.
I adopted this structure in my role as coaching director with an athletic development academy that operated across multiple sites during my time in New Zealand. We sorted the kids into three groups using this assessment and classification process and then tailored the approach and programming for each group accordingly. The protocol described was part of the gateway assessment for new recruits to assign them the appropriate group and the assessments were repeated periodically with the whole cohort for ongoing monitoring and to guide decisions on individual readiness to progress to the next tier.
On an individual basis, those supporting the young performer can similarly use the same tools and framework to guide their preparation. The priorities for physical and athletic development differ according to relative age and stage, as depicted below.
Originally published in Informed: The Art of the Science of Preparing Athletes. Reprinted with permission.
UNPACKING THE PRIORITIES WITHIN EACH PHASE…
During the earliest pre-adolescent or ‘pre-PHV’ phase that precedes the onset of puberty young performers are most receptive to motor learning. During this phase kids can certainly gain strength but mainly this is through becoming better able to harness what they have; until puberty hits we will not see marked gains in muscle mass. To explain the top line in the figure, the onus at this stage is discovering and developing movement capabilities and motor skills. In general, this is best achieved through exploration rather than more formal training - essentially figuring things out, negotiating obstacles and playing games that challenge them in different ways. All in all, the priority is acquiring fundamental movement skills and general athleticism, as we have spoken about before. That said, there will likely be a subgroup that is willing and ready for more formal instruction on strength training techniques and fundamentals of sprint mechanics, jump technique, etc. Girls especially can derive huge benefit from getting a head start on strength training in particular.
Following the onset of puberty we do start to see more marked changes, with spells of rapid growth especially for boys. As well as growing in stature, boys further benefit from free gains in strength, lean mass and speed. That said, this is a pretty volatile time - and during the multiple spells of rapid growth especially the respective structures of the growing limbs are under some strain. This also poses an ongoing coordination challenge as the young performer must continually adjust and recalibrate to accommodate their changing limbs. All of which means that whilst we can and should introduce more formal strength training and athletic preparation during this time we need to keep things relatively consistent and the focus remains on maximising the quality of every repetition rather than progressing load to maximise strength gains. There is a continued emphasis on general motor skills, which affords the young athlete the opportunity to continually refine and recalibrate coordination and body awareness as they adjust to their changing body and learn to harness the horsepower they are acquiring in the process.
For girls the picture is somewhat different, which calls for a bit of a different approach. Not only does puberty occur much earlier (on average commencing around age 12 but there is individual variation), the changes that occur during this phase are a lot different. Girls certainly grow in stature, gain mass and limbs become longer, but these changes are not accompanied by the free gains in strength and other capacities that boys enjoy. Consequently, this is a key window for strength training intervention to provide a necessary boost. At the very least strength at respective links in the chain must at least be able to match the extra length and inertia of the limbs and body segments. Without this strength development female performers are forced to find a way and adopt compensatory movement strategies that preferentially use the few anti-gravity muscles that do keep up (predominantly quadriceps), which is not optimal for performance and also predisposes to injury as highlighted previously. On that basis, as well as riding the puberty wave and managing stress and strain, we must seek to develop strength throughout this period, focusing on the hips and hamstrings particularly. Developing capability in relation to body and lower limb control to accommodate changes in mass and limb length is similarly a priority, including developing trunk strength and the ability to stabilise the lower limbs under dynamic weight-bearing conditions.
The post-PHV phase commences when the period of rapid growth ends and things become relatively less volatile. For girls, this is typically around a year and a half following the main adolescent growth spurt (on average this equates to roughly 14 years of age but does vary according to the individual). For boys, we typically need to wait a little longer (2+ years post PHV on the individual growth curve), so it is more a case of monitoring seated and standing heights and exercising professional judgement in deciding when we need to delay until things stabilise. Once they hit this phase, we can start to double down on strength training and other aspects of physical preparation with a view to making gains in strength, speed and fitness in pursuit of whatever performance goals are identified by the performer.
Early adolescence is a pivotal and formative phase for young people, so we should expect that they will assume a more prominent role and greater responsibility over this period. Hence by the time they reach this stage in their journey there will accordingly be an expectation that they are steering their own ship and that they are prepared to invest the necessary time and effort to pursue the goals they have identified. In the later teenage years young performers will typically nominate their chosen sport and settle on their long-term sporting aspirations. Now that we are dealing with young adults, the training process thus starts to more closely resemble the physical and athletic preparation of senior athletes but with appropriate accommodations for the fact that they are still developing.
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