Body Composition Values

Body Composition Values – Muscle Mass -2

Our body mass consists of two main components: Fat Mass (FM) and Lean Body Mass (LBM). As mentioned in our previous article, the terms of “lean body mass” and “muscle mass” are frequently used interchangeably by the device manufacturers deliberately; however, these two values are not absolutely the same. Lean body mass (LBM) includes bone mass, body fluid, and all other body tissues, as well as muscle mass. The subject of body tissues is a very comprehensive subject.  Epithelial Tissue,  which is found in the structure of internal organs,  Supportive  Connective Tissue, chich connects organs and muscles,  Nervous Tissue, which coordinates the senses and body functioning, can be given example to these tissues.

When  Muscle Mass  is mentioned the total mass of 3 types of muscular tissue in our body is meant:  

– Striated muscles (skeletal muscles or red muscles),
– Smooth muscles (muscles in our organs),
– Heart muscle (muscles in heart tissue only).

To summarize,

Muscle Mass = Total mass of the Muscular Tissues

Lean Body Mass = Body Mass – Fat Mass

How do we measure our muscle mass?

First of all, when we say muscle mass, we have to make sure which muscular tissue is mentioned. Usually, when people talk about muscle mass, they typically mean skeletal muscles. When dieticians or trainers talk about muscle and muscle mass, they mean our skeletal muscles. Because our musculoskeletal system is the only muscular system on whose mass we can effect by diet and workout programs, and it is directly related to our basal metabolic rate. You can strengthen your heart muscles with cardio exercises, however, you cannot achieve a mass change that will affect your volume or basal metabolic rate.

So we can rephrase our question as “How can we measure our skeletal muscle mass?”.

Magnetic Resonance Imaging Method

Magnetic resonance imaging (MR or MRI) is the exact way to calculate muscle mass and its percentage.

The MR device uses powerful magnets to create an image of your muscles and creates a magnetic field. This magnetic field rearranges hydrogen atoms in your body, and it releases the energy that the device uses to determine tissues.

MR is the gold standard for determining muscle mass and percentage, but it is very costly, and the knowledge of the radiologist or specialist who interprets the results is very important. For this reason, it is not a practical method, moreover, it has drawbacks due to radiation in terms of regular use.

Multi-Frequency BIA (Bio Impedance Analysis)

In our first article, we mentioned how to obtain body composition values other than body water mass. You can access the detailed explanation using the link below.

Body Composition Values – Total Body Water -1

What we want to draw your attention to is that the muscle mass value given by these devices is definitely not the skeletal muscle mass we question. It is not even the muscle mass we have described above (the total of all muscular tissues). The value provided by them is a value found by subtracting the bone tissue mass from the lean body mass. This bone tissue mass is the value obtained from a statistical table according to your age, height, and gender.

Briefly, what is provided by the BIA devices is the muscle mass value *;

muscle mass value* = Body mass – Fat mass – Bone mass.

As a result, this value includes all the tissues that make up our body such as all muscular tissues, body fluids, epithelial tissue, nervous tissue, and organ tissues. However, as mentioned in our first article and above, this issue is manipulated and this value is presented as the skeletal muscle system mass by the BIA device manufacturers, and this is presented to end-users in this way by the users in the industry.

In the figure below, the report of a top model Segmental BIA device from the most well-known BIA device manufacturer is presented as an example. As you can see they use the term Muscle Mass.   But you can see that this value is equal to Body mass – Fat mass – Bone mass , and that it’s not a measurement value, but a value calculated by a simple formula.

As a result, the value of the Muscle Mass given by BIA devices does not have anything to do with neither the muscle mass nor the skeletal muscle mass defined in the literature. This value is the estimated bone mass from the Lean Body Mass.

However, the Lean Body Mass is an effective follow-up value in Workout and Diet programs. Because we can assume that other tissues in our body, except for the musculoskeletal tissue, remain stable for 1-6 months during the workout and diet processes, when there is no advanced health problem. This means that the change in Lean Body Mass value is largely caused by the musculoskeletal tissue.