Skeletal muscle mass refers specifically to the muscles attached to your bones, responsible for voluntary movement, while muscle mass is a broader term encompassing all muscle tissue in the body, including skeletal, smooth, and cardiac muscle.
Breakdown of Skeletal Muscle Mass vs. Muscle Mass
To understand the difference, let's break down each term:
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Skeletal Muscle Mass:
- Definition: Muscles that are attached to the skeleton via tendons.
- Function: Responsible for voluntary movements like walking, lifting, and running.
- Control: Under conscious control.
- Measurement: Often assessed during body composition analysis to gauge physical fitness and health.
- Example: Biceps, triceps, quadriceps, hamstrings.
-
Muscle Mass:
- Definition: The total mass of all muscle tissue in the body.
- Composition: Includes skeletal muscle, smooth muscle (e.g., in the digestive system and blood vessels), and cardiac muscle (the heart).
- Function: Performs a wide range of functions, from movement to regulating organ function and circulating blood.
- Control: Skeletal muscle is under voluntary control; smooth and cardiac muscles are involuntary.
- Measurement: Determining the precise total muscle mass is complex, as it involves assessing all three types of muscle tissue.
Table Summarizing the Differences
| Feature | Skeletal Muscle Mass | Muscle Mass |
|---|---|---|
| Definition | Muscles attached to the skeleton | Total mass of all muscle tissue |
| Types Included | Skeletal muscles only | Skeletal, smooth, and cardiac muscles |
| Control | Voluntary | Voluntary and involuntary |
| Function | Movement | Movement, organ function, circulation |
Why the Distinction Matters
While "muscle mass" is the broader term, "skeletal muscle mass" is often the focus in fitness and health contexts because it's the type of muscle you can actively build and maintain through exercise. Increases in skeletal muscle mass contribute to strength, metabolism, and overall physical function. Changes in smooth or cardiac muscle are usually related to underlying health conditions, rather than voluntary training.
In summary, the key distinction lies in the scope: skeletal muscle mass is a component of overall muscle mass, focusing specifically on the muscles responsible for voluntary movement.
