Table 1.
Characteristics of study participants among the muscle-to-fat mass ratio tertiles.
| ALL (n = 113) |
Low MFR (n = 28) |
Medium MFR (n = 57) |
High MFR (n = 28) |
p-Value | |
|---|---|---|---|---|---|
| Age, year | 14.0 (13.0–15.0) | 14.0 (12.3–15.8) | 14.0 (13.0–15.0) | 14.0 (13.0–15.0) | 0.77 |
| Height, cm | 165.7 (158.4–171.8) | 166.9 (157.6–170.3) | 166.5 (157.9–173.2) | 165.0 (158.9–170.0) | 0.9 |
| Weight, kg | 55.7 (44.9–65.0) | 68.7 (51.7–80.8) | 56.8 (48.4–63.0) | 48.1 (44.2–57.8) | 0.0023 |
| Body mass index, kg/m2 | 19.7 (17.9–22.4) | 24.9 (19.5–28.0) | 20.2 (18.0–22.0) | 18.1 (16.6–19.3) | <0.0001 |
| Skeletal muscle mass, kg | 26.6 ± 7.0 | 27.3 ± 8.2 | 26.7 ± 7.4 | 25.6 ± 4.4 | 0.44 |
| Fat mass, kg | 7.2 (4.9–11.0) | 14.3 (10.2–23.4) | 7.4 (5.8–9.4) | 4.0 (3.1–5.1) | <0.0001 |
| Skeletal muscle mass/weight | 0.48 (0.45–0.49) | 0.43 (0.40–0.44) | 0.48 (0.46–0.49) | 0.51 (0.49–0.10) | <0.0001 |
| Fat mass/weight | 0.14 (0.11–0.18) | 0.22 (0.20–0.28) | 0.14 (0.12–0.16) | 0.08 (0.07–7.8) | <0.0001 |
| Skeletal muscle to fat mass ratio | 3.39 (2.57–4.64) | 1.94 (1.43–2.28) | 3.39 (2.87–4.07) | 6.38 (5.11–7.42) | <0.0001 |
| Hand grip, kg | 32.8 ± 9.5 | 33.4 ± 10.8 | 32.8 ± 10.0 | 32.0 ± 7.1 | 0.68 |
| Knee extension force, Nm/kg | 2.26 ± 0.45 | 2.00 ± 0.38 | 2.32 ± 0.43 | 2.40 ± 0.47 | 0.0029 |
| Knee flexion force, Nm/kg | 1.07 (0.94–1.26) | 1.00 (0.84–1.08) | 1.13 (0.99–1.33) | 1.10 (0.95–1.31) | 0.0068 |
| Squat jump, cm | 27.0 ± 6.1 | 22.5 ± 5.1 | 28.2 ± 5.7 | 29.0 ± 5.4 | <0.0001 |
| Counter movement jump, cm | 30.0 ± 6.0 | 25.6 ± 4.9 | 31.2 ± 5.7 | 32.3 ± 5.6 | <0.0001 |
| Aspartate aminotransferase, IU/L | 23.0 (19.5–25.5) | 24.0 (19.0–27.0) | 22.0 (19.0–25.0) | 23.5 (21.0–26.8) | 0.34 |
| Alanine aminotransferase, IU/L | 17.0 (14.0–23.0) | 22.0 (15.3–34.0) | 17.0 (13.0–22.0) | 15.0 (13.0–20.0) | 0.0028 |
| Gamma-glutamyl transferase, IU/L | 15.0 (13.0–19.5) | 16.5 (15.3–34.0) | 15.0 (13.3–26.0) | 15.5 (13.0–16.8) | 0.16 |
| Fasting blood glucose, mg/dL | 98.0 (94.0–102.5) | 99.0 (94.3–101.0) | 97.0 (94.0–102.5) | 97.0 (92.3–103.8) | 0.85 |
| Triglycerides, mg/dL | 68.0 (45.0–82.5) | 74.5 (45.3–130.0) | 68.0 (46.0–82.5) | 57.0 (43.8–71.3) | 0.048 |
| High-density lipoprotein cholesterol, mg/dL | 63.9 ± 12.2 | 63.7 ± 13.1 | 63.8 ±12.1 | 63.9 ± 12.2 | 0.96 |
| Obesity (body mass index > 25 kg/m2) | 18 (15.9%) | 13 (46.4%) | 5 (8.8%) | 0 (0.0%) | <0.0001 |
| Alanine aminotransferase (>26 IU/L) | 16 (15.0%) | 11 (39.3%) | 4 (7.0%) | 1 (3.6%) | <0.0001 |
Results are presented as mean ± standard deviation, median (interquartile range), or number (LRB%). Low MFR: <25th percentile; medium MFR: 25th–75th percentile; high MFR: >75th percentile. Abbreviations: MFR, muscle-to-fat mass ratio; n, number.