Muscle Size for Research


Muscle Size is considered here as the thickness of a muscle as measured by ultrasound at predetermined muscle locations. Research has shown that Muscle Thickness can be considered a surrogate for Muscle Mass/Volume, particularly in the lower limbs1-3.

Currently we are able to assess muscle size of the thigh, both the Rectus Femoris (RF) and the Vastus Lateralis (VL). Future assessments may include other muscles of the lower limbs, the Hamstrings (HL), the Calf/Gastrocnemius (GS), and upper limbs, such as the Biceps (BB).

Why is Muscle Size Important?

Skeletal muscle has a little known - but powerful - impact on a range of health issues. It is a unique and extensive body tissue that on average makes up approximately 40% of body mass, depending on gender, age and physical fitness.

While it is typically only thought of in a rather narrow fitness and sports related context, muscle also contributes to crucial health related functions including breathing, protein metabolism, digestion, blood circulation, immune system status, blood glucose regulation, and overall quality of life. The size of our muscles, therefore, is an important component of our “MuscleHealth” – defined as “The capacity of a muscle to store, generate and replenish energy”.

A recent review4 summarizing the role of muscle in health and disease has stated:

“It is imperative that factors directly related to muscle mass, strength, and metabolic function be included in future studies designed to demonstrate optimal lifestyle behaviors throughout the lifespan, including physical activity and diet”

Why is Muscle Size Important in Research?

Muscle Size is a component of MuscleHealth. Since little research has been conducted on this aspect of muscle as a relevant endpoint4, it is a topic of interest to investigators. The investigation of Muscle Size can produce a variety of “relevant end points” depending on the population.

In Frail populations, it allows the monitoring and tracking of...
  • Muscle mass levels in chronic disease conditions and/or ICU patients
  • Clinical rehab impact on muscle mass levels
  • Nutritional impact on muscle mass levels
  • Association of muscle mass levels with functional and clinical outcomes

NOTE: Research topics related to these outcomes would provide information essential to the health - and even the survival - of these populations, including the impact and progression of sarcopenia

In Free living populations, it allows the monitoring and determination of...
  • The age-related rate of muscle mass loss
  • The impact of exercise/strengthening interventions on muscle mass

NOTE: Research topics related to these outcomes would provide information clarifying the progress of Sarcopenia (the loss of muscle mass with aging), which has been described as “the single most frequent cause of late life disability”. Delaying or even transiently reversing the progress of sarcopenia, has been shown to improve physical function and quality of life5.

In Persons Active in Sports and Exercise, it allows the monitoring and determination of...
  • The impact of strength building programs on muscle size
  • Comparison of differing strength training protocols on muscle size
  • The symmetry of muscle thickness in contralateral limbs
  • Potential game-related injury risk

NOTE: Research topics related to these outcomes would provide information essential for developing effective rehab and/or training-related approaches to fitness and nutrition.

  1. Abe, T., et al. Morphological and functional relationships with ultrasound measured muscle thickness of the lower extremity: a brief review. Ultrasound 23: 166–173, 2015
  2. Abe, T., et al. Ultrasound assessment of hamstring muscle size using posterior thigh muscle thickness Clin Physiol Funct Imaging 36: 206–210, 2016
  3. Ogawa, M., et al. Ultrasound Assessment of Adductor Muscle Size Using Muscle Thickness of the Thigh. Journal of Sport Rehabilitation 21: 244-248, 2012
  4. Robert R Wolfe, R., The underappreciated role of muscle in health and disease. Am J Clin Nutr 84: 475–82, 1006
  5. Malafarina V, et al., Sarcopenia in the elderly: Diagnosis, physiopathology and treatment. Maturitas 71: 109–114, 2012.

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