What do levels of muscle fat tell us about muscle health?
Published in November 2021 in Europe PMC
With this study we wanted to test the idea that the amount of fat in your muscles can be a good indicator of muscle, hip and general health. To do this we compared the gluteus maximas muscles of different groups, ranging from the healthy and active to those who were inactive and suffering from hip pain.
Our aim was to find out whether fat infiltration in the gluteus maximus (GMAX) muscle is associated with different levels of physical activity, by studying one group of patients with hip pain, and three groups of healthy subjects with low, medium and high levels of physical activity.
We also wanted to determine the effect of female gender, older age, high BMI and hip pain/symptoms on the relationship between physical activity and fat infiltration of the GMAX. In the process we hoped to demonstrate a new tool for evaluating hip muscle health. This was a cross-sectional study involving seventy subjects that underwent Dixon MRI of the pelvis. We estimated the GMAX intramuscular fat content for each subject using automated measurements of fat fraction (FF) from MRI images.
We found that those with hip pain, low levels of physical activity, female gender and a higher body mass index tended to have greater amounts of fat in their gluteus maximus muscles. This suggests that fat infiltration into the gluteus maximus muscle could be really valuable as a marker of muscle health, good mobility and healthy hips.
In short…
The study
We wanted to assess ‘the muscle factor’ in people who were very active (more than 8 hours’ exercise per week), fairly active (4-8 hours a week) and inactive (less than 4 hours). We also studied a group of people being treated for current hip pain, who were unable to exercise.
We recruited 70 participants who met the requirements for the study and each one underwent MRI scans of the gluteus maximus muscles.
Advanced machine learning techniques made it faster and simpler to compare the level of fat infiltration in participants’ muscles.
What we found
The most active people had the lowest amounts of fat infiltration in their gluteal muscles. The patients with hip pain had the highest ratios of muscle fat, followed by the inactive group.
We found that hip pain, low physical activity, female gender and high BMI had a statistically significant relationship with increased GMAX fat infiltration.
What it means
Our research suggests that fat infiltration into the gluteus maximus muscle could be really valuable as a marker of muscle health, good mobility and healthy hips.
People who exercise a lot have the lowest levels of fat in their gluteal muscles, and strong muscles are known to help protect joints - in this case, the hips.
