Fitness for the youth athlete

This week, I am going to be talking about metabolic conditioning for young athletes which is what most people would refer to as fitness! To put it simply, we all have certain ways in which we produce energy for a given task. These ‘energy systems’ all work alongside one another but certain tasks can be more taxing on one of more energy system. For example, during a 100m sprint which requires all out, maximal explosive power over a very short duration will predominantly utilise the ‘ATP-PCr’ system (which is anaerobic) to create rapid muscular contractions. Activities that are still high intensity but slightly longer in duration (approx. 10-90s) utilise a method of producing energy known as the ‘glycolytic system’ (also anaerobic). Finally, we have activities that are longer in duration (minutes or even hours long!) and lower in intensity. These utilise the oxidative system (which is aerobic).  

Different sports have different energy requirements that can be dominant aerobically, anaerobically or a balance of the two, dependant on the demands of the sport, position, individual style etc.

When we talk about metabolic conditioning or fitness, the aim as an S&C coach is to improve the function and capacity of these energy systems. Whether that’s something like long continuous runs to improve aerobic function or repeated high intensity bouts to improve aerobic or anaerobic capacity. Either way, it’s important to ‘condition’ or better prepare these areas to improve performance.

Physiological and hormonal changes as you grow and mature has a big impact on a young athlete’s capacity to utilise aerobic and anaerobic energy systems. The way in which young athletes respond to endurance exercise differs based on some important factors including biological maturity and age. 

Prior to puberty, the glycolytic metabolic system (responsible for shorter duration, high intensity bouts of exercise) is less well developed and oxidative metabolism is predominantly utilised during exercise which means kids of this age are more aerobic in nature. A greater proportion of type 1 muscle fibres (predominantly aerobic) is also present.

This may lead to the conclusion that there is a limited anaerobic capacity and this form of training should be avoided during the pre-pubescent stage but this is not supported by the research. The training response to various forms of fitness training, whether that’s more anaerobic in nature with repeated short sprints and long recovery, or sub-maximal, longer aerobic runs, the training response is similar to that of adults. Pre-pubescent athletes are also able to recover quicker between bouts of higher intensity exercise. Various research has shown that high intensity interval training can improve performance in pre-pubescent athletes and so it does not need to be avoided.

There are some important areas that we can adapt including volume (total distance, number of reps etc.), intensity (higher intensity = more anaerobic in nature), design (interval or continuous) and mode (e.g. varying activities such as running, cycling, mobility circuit etc.)

Practically speaking, we don’t want a young athlete to burn out with copious amounts of high intensity fitness training every day! Adaptations to volume in particular is important! As athletes mature and develop a training base, the intensity and volume can gradually increase to that of senior athletes.

Continuous and interval modes of training are shown to improve endurance in young athletes but the interval format is better tolerated by youth athletes and possibly more engaging for some. There is research to suggest that we should limit high intensity interval bouts to 15s in pre-pubescent athletes but allow a short rest period due to their increased ability to recover.

Use a wide range of training modes to provide a broad training stimulus and reduce risk of overuse injuries from repeating sport specific movements. Cross-training modes may be better in earlier stages (especially pre-pubescent and early puberty) but have less transfer to sporting movements but is more beneficial to overall, long term physical development. It is important to still include movements from the young athlete’s sport but it just needs to be regulated in terms of volume, intensity and frequency.

Adaptations to training volume and intensity will be especially important during periods of rapid growth (growth spurts) in order to avoid risk of injury!

A BIG focus on movement quality should also be a priority in order to improve movement efficiency, resulting in better performance before you’ve even started improving metabolic ability, win-win! Another important point is that sessions HAVE to match the young athlete’s level of maturity (engagement is important) – i.e. there’s no point giving a 12 year old a long, boring run to complete 5 x a week as their aerobic conditioning, there would be minimal engagement! Games based conditioning with constraints in place to moderate work bouts and rest periods could be a great way to make the sessions fun but also achieve the desired training outcome!

Here a few examples (adapted from Gamble, 2014)…

Pre-puberty:

Session 1 – Cross training – long aerobic intervals (90s – 4 mins) x 20-30 mins total

Session 2 – Conditioning games (more anaerobic in nature, self-regulated recovery, 10-15s work bouts with 15 – 60s rest) x 15-20 mins total

Session 3 – Running based (if that is the specific movement in the sport) – long aerobic intervals – long aerobic intervals (90s – 4 mins) x 20-30 mins total

During puberty:

Session 1 – Cross training – aerobic/anaerobic intervals (20s:20s – work:rest, high intensity) x 10-20 mins total

Session 2 – Conditioning games – short aerobic intervals (10-30s work bouts with 15 – 60s rest, moderate intensity) x 15-25 mins total

Session 3 – Running based (if that is the specific movement in the sport) – long aerobic intervals – long aerobic intervals (90s – 6 mins, moderate-high intensity) x 20-35 mins total

Post-puberty:

Session 1 – Cross training – anaerobic intervals (5-30s sprints, 1-4 min rest, max intensity) x 10-20 mins total

Session 2 – Conditioning games – long aerobic intervals (90s – 6 mins work, up to 2 mins rest, high intensity) x 20-40 mins total

Session 3 – Running based (if that is the specific movement in the sport) – aerobic/anaerobic intervals (20s:10s work:rest, high intensity) x 10-20 mins total

Session 4 – Skill based conditioning – short aerobic intervals (10-30s bouts with short recovery, moderate-high intensity) – 15 – 30 mins total

Gamble, P. (2014). Metabolic conditioning development in youths. In: Lloyd, R. and Oliver, J. Strength and conditioning for young athletes: science and application. Oxon: Routledge. p120-131.