A total of 151 men participated in this study. According to EWGSOP criteria, sarcopenia was defined in 45 (29.8%) men. Basic descriptive characteristics of the study population are shown in Table 1.
Sarcopenic men were older, with lower weight and BMI as well. Moreover, mean BMI score in all groups belong to pre-obesity status. In addition to this, lean mass, appendicular lean mass, arm lean mass, leg lean mass, and skeletal muscle mass index, handgrip strength, and gait speed were lower in sarcopenic men. Fat mass was also lower in older men with sarcopenia. Whole body, femoral neck and total hip BMD as well as whole body, femoral neck and total hip T-score and BMC were higher in non-sarcopenic men; however, no difference was found between lumbar spine BMD and T-score in non-sarcopenic and sarcopenic men. The largest proportion of men with T-score equal to or below − 1.0 was found in the sarcopenic group, where more than 86 percent of men could be classified as having osteopenia.
When analyzing bone health measures and body composition in older men with sarcopenia, it was found that multiple associations exist between bone health and body composition (Table 2).
Table 2
Correlations between specific bone health measures and body composition parameters in sarcopenic men.
Bone health measures | Lean mass | Appendicular lean mass | Arm lean mass | Leg lean mass | SMMI |
Femoral neck BMD | r = 0.418 p = 0.006 | r = 0.5 p = 0.001 | r = 0.576 p < 0.001 | r = 0.435 p = 0.004 | r = 0.347 p = 0.024 |
Hip BMD | r = 0.374 p = 0.013 | r = 0.475 p = 0.001 | r = 0.489 p = 0.001 | r = 0.431 p = 0.004 | r = 0.372 p = 0.014 |
Whole body BMD | r = 0.37 p = 0.015 | r = 0.44 p = 0.003 | r = 0.451 p = 0.002 | r = 0.382 p = 0.011 | r = 0.382 p = 0.012 |
Femoral neck T-score | r = 0.446 p = 0.003 | r = 0.52 p < 0.001 | r = 0.564 p < 0.001 | r = 0.411 p = 0.007 | r = 0.362 p = 0.018 |
Total Hip T-score | r = 0.417 p = 0.005 | r = 0.505 p = 0.001 | r = 0.538 p < 0.001 | r = 0.422 p = 0.005 | r = 0.398 p = 0.008 |
Whole body T-score | r = 0.37 p = 0.015 | r = 0.442 p = 0.003 | r = 0.457 p = 0.002 | r = 0.382 p = 0.011 | r = 0.382 p = 0.012 |
SMMI – skeletal muscle mass index, aSM – appendicular skeletal muscle mass, BMD – bone mineral density, BMC – bone mineral content, r – Pearson r, r – Spearman r |
As shown in Table 2, acceptable and good positive correlations were found between some bone health measures and body composition parameters. Furthermore, positive correlations were also found between fat mass and hip BMD (r = 0.31, p = 0.043) as well as whole body BMD (r = 0.372, p = 0.014). In addition, gynoid fat mass was positively associated with whole body T-score (r = 0.317, p = 0.038). An acceptable correlation was found between lumbar spine T-score and SMMI (r = 0.323, p = 0.035).
Bone health measures in sarcopenic men were not only associated with body composition, but with physical performance as well. SPPB score positively correlated with femoral neck BMD and T-score (r = 0.223, p = 0.008; r = 0.219, p = 0.009, respectively). Gait speed was positively associated with femoral neck T-score and hip T-score (r = 0.45, p = 0.002;r = 0.39, p = 0.007, respectively). A relationship was found between balance test and T-score of femoral neck (r = 0.45, p = 0.002) and hip (r = 0.3, p = 0.04). Balance test was also associated with femoral neck BMD (r = 0.442, p = 0.003), BMC (r = 0.445, p = 0.003) and whole body T-score (r = 0.368, p = 0.015). No correlations were found between 5 chair stand test results and any bone health measure. Handgrip strength had positive associations with femoral neck BMD, hip BMD, whole body T-score and BMC (r = 0.386, p = 0.011; r = 0.385, p = 0.01; r = 0.419, p = 0.005; r = 0.387, p = 0.011, respectively). Correlations between handgrip strength and femoral neck and hip T-scores are shown in Fig. 1.
Some of the body composition parameters were associated with physical performance tests. Gait speed had positive correlation with appendicular lean mass (r = 0.323, p = 0.037) and arm lean mass (r = 0.327, p = 0.035). Moreover, balance test was associated with appendicular lean mass and arm lean mass as well (r = 0.347, p = 0.024; r = 0.384, p = 0.012, respectively), as with SMMI (r = 0.334, p = 0.031). Skeletal muscle mass index also had an acceptable positive correlation with handgrip strength (r = 0.342, p = 0.027). No associations were found between leg lean mass and gait speed (p = 0.056) or balance (p = 0.054), and between 5 chair stand test and body composition parameters.
A few body composition parameters were associated with handgrip strength (Fig. 2).
Out of 45 men with sarcopenia, 38 agreed to undergo a procedure of muscle biopsy. Eight out of those men had contraindications for biopsy: 2 were taking anticoagulants at the time and 6 had a confirmed case of arrhythmias. Out of 30 muscle microbiopsies performed, 25 samples were informative, because 2 microbiopsies had insufficient samples and 3 had higher than the accepted count for altered fibers. A picture of muscle morphology sample can be seen in Fig. 3.
On average, muscle fiber length was 217.47 ± 25.22 microm, the smallest length was 183.47 microm and the longest – 255.83 microm. Fiber cross-sectional area varied from 139 to 6116 microm2. Average fiber cross-sectional area was 2446 ± 608.87 microm2. The number of type I fibers counted was 168.75 ± 89.35 and of type II fibers, it was 126.25 ± 74.87. Type I fibers made up 57.28% of all fibers.
No significant correlations were found between muscle fiber length and whole body, lumbar spine, femoral neck or hip BMD (p = 0.18, p = 0.43, p = 0.19, p = 0.65, respectively) or bone mineral content (p = 0.25). Muscle fiber area did not correlate with bone health measures (BMD and BMC) as well. No correlations between muscle fiber length or area and T-score in whole body, lumbar spine, femoral neck or hip were found as well. Body composition parameters, such as fat mass, android and gynoid fat mass, lean mass, appendicular lean mass, arm and leg lean mass were also not associated with muscle fiber length or muscle fiber area. Moreover, no correlations were found between muscle fiber length or area and physical performance (balance test, 5 chair stands and gait speed) or muscle strength (handgrip strength).
In nine sarcopenic men with T-score ≤ 2.5, muscle fiber area had a good positive correlation with results of balance test (r = 0.73, p = 0.025). No other associations were found between muscle fiber length or area and bone health measures, body composition, physical performance or muscle strength. In other 16 men, no correlations were found between muscle morphology, BMD, body composition, physical performance and muscle strength.