Table 3.
Characteristics of the long-term-discordant MZ twin pairs
| Variable | Active (n = 10) | Inactive (n = 10) | Mean difference (95% CI) | p value |
|---|---|---|---|---|
| Physical activity* | ||||
| 3-year-LTMET index (MET-h/day) | 5.0 ± 2.7 | 1.7 ± 1.3 | 3.3 (1.9 to 4.8) | 0.001 |
| 12-month-LTMET index (MET-h/day) | 3.9 ± 1.2 | 1.2 ± 0.9 | 2.8 (2.0 to 3.5) | < 0.001 |
| Body composition* | ||||
| Lean body mass (kg) | 56.9 ± 4.8 | 55.5 ± 6.1 | 1.4 (− 0.3 to 3.0) | 0.094 |
| Fat mass (kg) | 16.0 ± 4.5 | 19.2 ± 6.6 | − 3.3 (− 6.7 to 0.2) | 0.059 |
| Body fat percentage (%) | 20.7 ± 4.0 | 24.0 ± 4.6 | − 3.3 (− 6.2 to − 0.4) | 0.029 |
| Cardiorespiratory fitnessa | ||||
| VO2peak (l/min) | 3.3 ± 0.3 | 2.9 ± 0.5 | 0.4 (0.2 to 0.6) | 0.001 |
| VO2peak (ml/kg LBM/min) | 58 ± 5 | 52 ± 5 | 7 (3 to 10) | 0.001 |
| Metabolism at restb | ||||
| REE (kcal/day) | 1735 ± 187 | 1675 ± 191 | 59 (− 48 to 166) | 0.24 |
| RER | 0.82 ± 0.03 | 0.80 ± 0.03 | 0.02 (− 0.01 to 0.04) | 0.16 |
| RFO (g/min) | 0.06 ± 0.02 | 0.06 ± 0.02 | 0.00 (− 0.01 to 0.01) | 0.52 |
| RFO (mg/kg LBM/min) | 1.0 ± 0.3 | 1.1 ± 0.3 | − 0.1 (− 0.3 to 0.1) | 0.35 |
| Fat oxidation during exercisea | ||||
| PFO (g/min) | 0.46 ± 0.20 | 0.38 ± 0.12 | 0.08 (− 0.02 to 0.18) | 0.11 |
| PFO (mg/kg LBM/min) | 8.0 ± 3.1 | 6.9 ± 1.8 | 1.1 (− 0.7 to 2.9) | 0.18 |
| FATMAX (%VO2peak) | 40 ± 9 | 43 ± 8 | − 4 (− 8 to 1) | 0.077 |
LBM lean body mass, MET metabolic equivalent of task, OGTT oral glucose tolerance test, PFO peak fat oxidation, REE resting energy expenditure, RER: respiratory exchange ratio, RFO resting fat oxidation, VO2peak peak oxygen uptake
*Data reported earlier (Rottensteiner et al. 2015)
an = 9 MZ twin pairs
bn = 9 MZ twin pairs, one pair is different than in the exercise test-based variables