A common question around our clinic, and the Universal Exercise Unit, is why are we using relatively light resistance and higher repetitions for strength training in children, especially since many trainers and physical therapists recommend fewer repetitions and larger amounts of resistance for maximum strength gains in adults?  The answer lies in the developmental differences between how children and adults make functional strength gains. 
 
In adults, strength training causes the muscle fibers to get thicker or hypertrophy.  The increased size of the muscle fiber produces the gain in muscle mass we see in adults who are strength training and leads to functional strength gains.  In order to maximize muscle hypertrophy and an adults ability to "build" muscle, heavier weights at lower repetitions are recommended over the course of 6-8 weeks of consistent strength training.  Some trainers even use a one rep max (the maximum weight a person can lift just once) when lifting weight with a goal of building muscle.
 
In contrast, for children, functional strength gains are produced as a result of improved motor unit recruitment. This process does not result in muscle hypertrophy and while we may see improved definition in the muscle when contracted, the overall size of the muscle does not grow.  By increasing the number of repetitions used in each set of a strengthening exercise we allow the child more opportunities to practice a given motor pattern against a set resistance and produce the necessary motor learning to allow them to more effectively recruit motor units when a task demands increased strength.  By using lighter weights, we allow a child to actively participate in more repetitions or opportunities for practicing efficient and effective motor unit recruitment prior to fatigue.
 
A child begins building muscle through fiber hypertrophy after puberty and thus, for purely functional strength goals, a strength training protocol needs to take into consideration the development of a child's body and make appropriate adjustments as their body changes.  That being said, in certain circumstances, a pediatric physical therapist may continue to use higher repetitions and lighter weights while working with children that have already entered puberty if their goals are not necessarily purely strength based, but rather motor control, selective muscle activation, or endurance based. 
 
References:
1)      Faigenbaum A, Kraemer W, Blimkie C, Jeffreys I, Micheli L, Nitka M, Rowland T.  Youth resistance training: updated position statement paper from the national strength and conditioning association. J Strength Cond Res. 2009;23(Supplement 5): S60-S70.
2)      Raynor AJ. Strength power and co-activation in children with developmental coordination disorder. Dev Med Child Neurol. 2001; 43:676-684.
3)      ACSM's Guidelines for Exercise Testing and Prescription, 7th Ed. Baltimore, MD: Lippincott Williams & Wilkins; 2006.
 

 

Now that we have a new Occupational Therapist (OT) on staff, we are working to get you more information related to fine motor skills. To start, here is a list of basic fine motor and visual milestones. 

 

2-4 months
Reaches for objects, but inaccurately 
 
3-7 months
 
4-8 months
 
4-10 months
 
7-9 months
 
7-12 months
 
12-18 months
 
2 years
 
2 ½-3 years
 
3-3 ½ years
 
3 ½- 4 years
 
4-4 ½ year
 
4 ½-5 years
 
5 years
 
5 ½-6 years
 
6 years