Is strength training for children healthy?

When anyone mentions strength training for children some coaches will get a picture in their head of a young child trying to use the weights you would expect to find in an adult gym. This picture generally describes weight lifting rather than strength training but as these terms are often used interchangeable, it is easy to get them confused. Context is important and in this case, we are talking about children building strength through playing games and building functional movement patterns. 

While we know the general benefits of strength training include improving overall fitness, increasing lean body mass, burn calories and increase bone density, it has also been shown to improve mental health. Developing our young ninja’s appropriately through our martial arts classes means that we should include some form of strength training. As well as delivering the benefits already mentioned and enabling them to perform well in other physical activities they take part in, it also helps prepare them for the next level of martial arts training.

Reducing dropout

Children that fail to build muscular strength and motor skill proficiency early in life tend to feel less confident and competent in their physical abilities. This is turn can limit their full participation in their martial arts classes while also increasing the chance of them dropping out. Recent research has shown that due to an increase in sedentary behaviour, strength levels in children have been dropping over the last 10 years. This trend has not just been seen in Britain but in Holland, Spain and Australia too. The worry is that these children are also several times more likely to be overweight or obese by the end of their time in primary school.

Strength training for children all ages

Strength is the maximal force you can apply against a load. Although strength training may see the biggest growth during the adolescent years (when there is an increase in growth hormones being produced), current research suggests that strength training should be a priority for children of all ages. In fact, strength training has a big impact on training speed, power, agility and endurance. The key to doing this safely is that the children are supervised and monitored by coaches with an appropriate levels of skill.

Preventing injury

Strength training can also have a significant impact on the development of fundamental movement skills and can help prevent sports related injuries. This risk is particularly higher in primary school aged children that have a higher level of aerobic ability and lower levels of strength. UK Coaching suggest that up to 50% of overuse injuries in children could be prevented by including an appropriate strength training in their programmes. Strength training can also help females build bone density to help reduce the risk of osteoporosis later in life as well as helping with joint laxity.

Youth Physical Development (YPD) Model

In the past, it has been suggested that children should not take part in resistance training and that doing so may even limit their growth or damage their joins. In 2012 Rhodri Lloyd and Jon Oliver published the Youth Physical Development model suggesting that not only would strength training not be detrimental to the health of children, but was recommended. The YPD model seen in figure 1 is based on chronological age with the emphasis on the different types of training changing to match maturation status of the students. The bigger the writing the bigger the emphasis for that element at that age. As you can see, strength training has a major focus from early childhood, all the way through to adulthood. The difference between the male and the female model is the same until puberty arrives. As we are currently focusing on younger children between the ages of 3-6, we will leave the subject of strength training for teenagers for another time.

Youth Physical Development Model

Strength training for 3-4 year olds

At 3 and 4 year old, children are still in the early stage of their development. That said by 3 years old the children will have already developed a dominant side when performing different actions and their gait (walking pattern) will already be defined. At birth, a baby’s head is roughly half the side of an adult head. If you have ever seen a 3 year old trying to perform a sit up, you will recognise that they often look like a turtle on its back trying to right itself. On average, they have not yet developed the core strength needed to be able to stabilise the body to perform some of the most basic body weight exercises.


So what is the solution? We focus on basic core based static positions to build the much needed core strength before moving on to more dynamic strength exercises. These positions can be as simple as standing straight with their feet together and their arms straight above their head (standing pencil) or sitting on the floor with their legs together in front of them and their arms as straight as they can above their heads (L sit or pike). As gymnastics is an early adaptation sport, they have already created a range of body positions that we can use knowing that they have been tried and tested with young children for a sustained period of time. As it does not make sense to reinvent the wheel, using these static positions can give the children a great foundation of strength before they start practicing other more advanced functional strength movements. Including foot positions in your coaching points can also help with foot formation for kicks if you are delivering a striking based martial art like Taekwondo, Karate or Kung Fu.

Strength training for 5-6 year olds

At 5 and 6 years old, you have more options and can start developing the children’s Functional Movement Patterns (FMP). These are strength based movements that the children will not only use frequently through childhood but for the rest of their lives. These functional movements generally include squatting, lunging, pushing, pulling, hinging, bracing, rotating and walking while carrying additional weight. Where possible try to focus on technique and if necessary, include the use of equipment to help them maintain good form. An example of this would be putting a couple of kick pads behind them so that their bum has to touch the pads when performing squats or asking them to start their press ups with their hands under their chin so you don’t just get the familiar head nodding without bending their arms. They are actually forced to lift their body off the floor for each repetition.

As well as body weight exercises we also have some soft leather medicine balls that we use with the children. These are great to exercise muscle groups where you would struggle to hit only using body weight resistance exercises. It’s also a bonus that if they drop them on their feet, it will not do them any damage. Resistance bands can also be used but close supervision is required. Most injuries experienced during strength training with children are down to poor technique or the misuse of equipment.


  • Strength training offers great health and fitness benefits to children of ALL ages. Integrating age appropriate strength exercises in to your martial arts programme for young children will only help their development
  • Low levels of strength correlates with lower levels of confidence and competence, this in turn can increase changes of drop out
  • In addition to improving overall fitness, increasing lean body mass, burning calories and increase bone density, strength training has also been shown to improve mental health
  • Make the inclusion of strength exercises progressive with a focus on technique while also preparing differentiations for exercises so you can pitch them at the right level for different individuals

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