Appendicular Lean Mass Index (ALMI): What is it and Why does it Matter?

March 27, 2024

Body composition tests provide detailed information about the distribution and percentage of muscle, fat, and other tissues. Among a wide range of values in body composition test results is Appendicular Lean Mass Index (ALMI). How much do you know about ALMI? In order to get the most from your training regimen and to truly understand body composition, it’s important to understand appendicular lean mass index.

What is Appendicular Lean Mass Index (ALMI)?

Appendicular lean mass index (ALMI) is a measurement used in body composition analysis to describe the amount of lean muscle mass in the appendicular skeleton, which includes your arms and legs.

The appendicular skeleton is one of two major bone groups in the human body. It comprises the upper and lower extremities with shoulder girdle and pelvis, which serve as connection points. The adult human body contains 206 bones, but 126 belong to the appendicular skeleton.

Appendicular lean mass index is valuable for evaluating muscle mass, especially in cases when the changes in muscle mass are of clinical significance. Good examples are older adults and people with cachexia (illness-related muscle wasting) or sarcopenia (age-related muscle loss). The general population can also benefit from ALMI assessment because it provides a better insight into body composition and how to adjust training accordingly.

Why is ALMI important?

The main advantage of body composition tests is that they show how much fat or lean mass you have in the body. While this information is incredibly useful, it’s also important to gain a deeper insight into regional distribution. Paying attention to ALMI is necessary for a wide range of reasons, including the following:

● Independence and functionality: Arms and legs are crucial for functionality and independence. Higher lean mass in your limbs is associated with increased strength, mobility, and balance. More precisely, good ALMI improves your quality of life.

● Diagnosis of sarcopenia: low ALMI values act as diagnostic criteria for sarcopenia, the age-related progressive loss of muscle mass and strength. The most common symptom of sarcopenia is muscle weakness, but people also experience other symptoms such as poor balance and falls. The prevalence of sarcopenia in people aged 60 years or older is 5% to 13%. Having an ALMI score lower than 1.12 lb/ft2 for women and 1.43 lb/ft2 for men indicates the presence of sarcopenia. That means your lean mass in limbs is lower than normal.

● Indicator of metabolic health: A higher percentage of muscle mass relative to the fat exhibits protective effects against metabolic diseases. A low ALMI score could serve as an indicator of poor metabolic health.

● Injury risk: Evidence shows that men should focus on increasing muscle mass in order to reduce the risk of injury, while women should prioritize reducing body fat. Your ALMI score shows how much muscle mass you have in your arms and limbs, which may help you evaluate susceptibility to injury. This is particularly important for athletes and active people who want to take their athletic performance to the next level.

● Tracking progress: ALMI helps athletes or active men and women track their training regimen. Also, ALMI can be used to assess recovery after serious injury, the progression of sarcopenia, and the effectiveness of treatment protocol.

Appendicular Lean Mass Index (ALMI) vs. Fat-Free Mass Index (FFMI)

Appendicular lean mass index, or ALMI, and fat-free mass index (FFMI) are measurements in body composition analysis, but they focus on different aspects of lean body mass. ALMI is primarily about lean muscle mass in your arms and legs, whereas FFMI considers the entire fat-free mass in your body. So, FFMI may include bone mass, muscle mass, and other non-fat tissues.

The use of FFMI is common in sports and fitness contexts to evaluate muscularity and body composition, especially in athletes and bodybuilders. This analysis offers a broader view of overall lean body mass.

What makes ALMI stand out among tests such as FFMI and calculations like BMI is that it’s more detailed. For example, BMI evaluates your weight relative to your height and provides a general indication of whether you’re underweight, overweight, or within a healthy weight range. ALMI goes a step further. Rather than producing a general overview or incorporating total lean mass, it focuses on lean mass in your limbs only.

How is Appendicular Lean Mass measured?

The most common and accurate measurement technique for assessing limb lean mass is a dual-energy X-ray absorptiometry (DEXA) scan. DEXA is a quick, painless, and noninvasive scan that measures body composition and bone density by passing high and low-energy beams to scan your tissues. The scan involves lying on your back on a table while a C-arm attached to it scans your body. It takes around 15 minutes to complete the scan.

While DEXA estimates the total amount of lean tissue, it doesn’t directly measure muscle mass. However, ALMI derived from the DEXA scan is the sum of lean tissue in the arms and legs. The main advantage of the DEXA scan is that it shows regional body composition results so you gain an insight into the distribution of fat and muscle mass in different body parts. That’s why it’s such a useful and accurate measurement for appendicular lean mass.

Once the appendicular lean mass is derived, it can be standardized to height to get ALMI. The ALMI results should be interpreted within the context of your age, gender, and ethnicity.

A paper from the journal Bone confirms that the DEXA scan is accurate in measuring body composition in a wide range of body sizes and body types. It provides regional body composition measurements by subdividing your body into several cut lines. It calculates your ALMI through this formula: arms + legs lean mass/height2.

What is a normal ALMI?

The appendicular lean mass index is expressed in kg/m2, i.e. lb/ft2. Reference value for ALMI in men is >1.43 lb/ft2 (>7 kg/m2) and >1.12 lb/ft2 (>5.5 kg/m2) for women.

If you’ve never done a body composition test, especially a DEXA scan, the ALMI score may seem difficult to understand. The reality is entirely different, though. When you do a DEXA scan at Fitnescity, you also receive access to the personal dashboard. The dashboard displays all the results and how they compare to other people of the same age, gender, and size. It shows whether your scores, including ALMI, are normal or not.

Tips to improve lean mass in arms and legs

If you’re not satisfied with the ALMI score, there’s a lot you can do to achieve better results next time. Here are a few tips to improve lean mass in your limbs:

● Engage in strength training 2-3 times a week

● Modify movements when necessary

● Perform exercises that target your arms and legs specifically

● Stay hydrated throughout the day

● Add more protein to your diet

● Avoid fatty and sugar-laden foods

● Don’t skip meals

● Combine higher and lower-strength exercises

● Get enough sleep

Conclusion

Appendicular lean mass index represents the amount of muscle mass in your arms and legs. This score provides more information about the risk and progression of sarcopenia, recovery after injury, effectiveness of training regimen, and so much more. The easiest way to learn more about your ALMI is to get a DEXA scan at Fitnescity.