HIIT Training: High-Intensity Interval Training
Nowadays, high-Intensity Interval Training (HIIT Training) is viewed as one of the most effective ways of improving the endurance capacity of the players.
From little on boys and girls have the dream of becoming a professional hockey or soccer player: they dream of winning league titles and playing in the World Cup final. However, only some are lucky enough to get scouted for a professional youth academy. Even though they have to train 4 or 5 times a week, which has a big impact on their social lives, they are willing to give that up to fulfil their dream. Around the age of 10-12 (girls), and 13-14 (boys) the talented players are starting to experience their growth spurt. But what are the risks of the growth spurt for these talented players? And how can you deal with the consequences as a trainer or coach? In today’s blog we will try to find answer to these questions.
In the sports science literature the growth spurt is often referred to as peak height velocity: a maximum rate of growth in height1 . However, not all players experience the growth spurt at the same time, which results in early, average and late mature players. It has been found that the difference in height for early and late maturing players in the same age group is on average 15 cm2. As you can imagine, this difference has quite a big impact on the physical output the talented players can deliver: early maturing players being stronger and faster than their later maturing teammates.
Since there are differences in the physical status of the players in these age categories, this also influences the amount of load that they can cope with. Let’s say we have planned a game format of 10v10, this means that players are exposed to a high sprint intensity (sprint meters/min). This game format might be perceived as ‘somewhat hard’ for the players who have already experienced their growth spurt, whereas the same game format might be perceived as ‘hard’ for the late maturing players. In this case, the external load (e.g. sprint meters) is the same, whereas the internal load is different (e.g. RPE). This difference is caused by the individual differences in maturity status (see image 1).
To overcome overloading of the late maturing players (and also an underloading over the early maturing players), training in two groups could be a solution. However, this is often hard to implement for practical reasons (i.e. player and staff availability). It is therefore of utmost importance to monitor both the external load and the internal load of the players. This way, we get insights into the abilities of each individual player to cope with certain loads, and adjust our training sessions accordingly (e.g. late maturing players performing less repetitions than other players).
In addition to the fact that differences in the maturity status of players possibly leads to overloading late maturing players, the growth spurt itself also increases the risk of injury. During the growth spurt there is a difference in growth speed of different structures: bones grow faster than muscles and tendons. Due to this imbalance, most adolescents in their growth spurt often experience some ‘clumsiness’, which increases the risk for traumatic injuries. During this period, it is therefore important to put more focus on balance/coordination exercises, to help the players adjust to their growing bodies. Furthermore, due to this imbalance, the muscles and tendons are more easily overloaded. Since training often involves accelerating and decelerating (which places high loads on the muscles and tendons) the growth spurt can lead to overuse injuries as well. Once more highlighting the importance of monitoring the internal load (and possibly pain scores after training), to minimize the risk of overuse injuries.
In today’s blog we have seen that the growth spurt leads to differences in maturity statuses of youth players within a team. This might lead to overloading the late maturing players. Furthermore, due to the differences in growth speed of the different structures, the growth spurt itself also increases the risk of injury. These two factors highlight the need to monitor the external load, but especially the internal load (and possibly pain scores after training), to minimize the risk of injuries for this age category. Useful tools to monitor the internal load are forms or an RPE-based mobile team app.
By measuring the length of each player every month, we get insights into when the players are experiencing their growth spurt. If a player grows more than 0.6 cm per month, there is a 1.6 times increased risk for injury3 . So start monitoring the length of the players of your team to know which players are in their growth spurt and therefore have an increased risk of injury!