Why Size Does Not Equal To Strength


FACT: SIZE DOES NOT always EQUAL TO STRENGTH. I understand where the logic comes from. The opposing belief seems viable when comparing a toddler to an adult; in which case then yes, size will likely equal to strength. Here I am speaking about the context of physical fitness and athletic performance in adults because although this principle applies to children and young adults when comparing them within the same age category, it’s hard to compare growing children because neither age group are physically mature yet. The truth I want to highlight is that size is not a true measure of strength due to the complex structures which exist within the human body.

On several occasions, in a group class setting, I’ve had women react with complete surprise at how strong I am for such a small person. In Asia, I would say I’m of average size, but I guess to the rest of the world I am what some would consider petite. I am 160cm (approx. 5’ 2’’) and my weight fluctuates between 47 kg-50 kg (approx. 103-110 lbs), but through my athleticism and commitment to training over the years I’ve been able to develop great strength for my size.

Here’s what’s important to understand. Muscle strength is not a matter of size, rather, muscle strength is a matter of force and velocity, which simply put is what allows for muscle contraction to occur. It’s possible to be small in appearance and size but strong in strength. Force is defined as strength or momentum which propels physical action or movement, while velocity is defined as the speed of the movement.

When training for strength, understand that there’s a whole lot more going on under the skin than just lifting, pushing, and moving. What needs to be classified is whether you’re training for size or training for performance and endurance. This difference in classification is what will differentiate between the type of training that’s best to achieve the desired goal. At its scientific level, muscle hypertrophy or muscle growth can occur in two ways: myofibrillar hypertrophy and sarcoplasmic hypertrophy. Neither of the two are better than the other, nor do they exclusively occur independently of one another, but the distinction creates an emphasis on why defining the goal for training matters.

First understand that each muscle fiber is an individual cell with multiple nuclei. Contraction or shortening of the individual muscle fiber is ultimately responsible for contraction of a whole muscle. Myofibrillar hypertrophy is an increase in the size or thickness of the cellular structures of the muscle fiber through the increase in myofibrils within each muscle fiber. An increase in myofibrils improves the force-production of individual muscle fibers because myofibrils is what contains the contractile (active) proteins: actin and myosin, which what makes muscle contraction possible. Sarcoplasmic hypertrophy is an increase in the volume of the semi fluid which surrounds individual muscle fibers but doesn’t contain the contractile proteins actin and myosin. Sarcoplasmic hypertrophy prioritizes on muscle fibers which contain the proteins used for tissue repair and growth. The increase in volume is what people refer to as muscle “pump,” as this situations creates increased cross-section of muscle fibers, but the enhancement in appearance and size is caused by an increase in semi fluid, but the semi fluid does not impact the contractile capacity of the muscle fibers and therefore does not impact force production. This is why identifying the goal to training is important.

Not all training are made equal because beyond the aesthetic and physical efforts there’s a lot of complex physiological, neurological, and chemical reactions and relationships which occur underneath the skin; beyond what meets the eye. This is why cardio may not be the best for weight loss and why strength training is advocated by many health professionals, because if size alone is what’s desired then there are specific methods of training which are more favorable to such goal while the same is true if performance is what’s desired more. At the end of the day, this is why narrowing to more specific goals and having a clear understanding on what the desired outcome is, beyond just being toned and fit is important.


McCall, Pete. “10 Things to Know About Muscle Fibers.” ACE, 7 May 2015, www.acefitness.org/education-and-resources/professional/expert-articles/5411/10-things-to-know-about-muscle-fibers.

Neumann, Donald A., et al. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. Third ed., Elsevier, 2017.