Table 1.
Effect of knee-extension training in normoxia vs. hypoxia during “living high” on muscle fiber type composition and capillary contacts per fiber.
| TRNOR | TRHYP | |||
|---|---|---|---|---|
| Pretest | Posttest | Pretest | Posttest | |
| RELATIVE FIBER NUMBER (%) | ||||
| Type I | 58 ± 3 (42–71) | 54 ± 4 (36–71) | 55 ± 5 (31–73) | 57 ± 4 (34–72) |
| Type II | 42 ± 3 (29–58) | 46 ± 4 (29–64) | 45 ± 5 (27–69) | 43 ± 4 (28–66) |
| RELATIVE FIBER CSA (%) | ||||
| Type I | 45 ± 1 (42–49) | 46 ± 1 (42–49) | 46 ± 1 (41–50) | 46 ± 1 (41–56) |
| Type II | 55 ± 1 (51–58) | 54 ± 1 (51–58) | 54 ± 1 (50–59) | 54 ± 1 (44–59) |
| FIBER CSA (μm2) | ||||
| Type I | 4614 ± 298 (3526–5530) | 4477 ± 276 (3460–5587) | 4639 ± 371 (3495–5995) | 4162 ± 288 (3119–5185) |
| Type II | 5452 ± 239 (4638–6154) | 5300 ± 423 (4036–7092) | 5610 ± 446 (3824–6873) | 5276 ± 541 (3732–6874) |
| CAPILLARY CONTACTS | ||||
| Type I | 5.0 ± 0.3 (4.1–6.6) | 5.7 ± 0.4* (4.4–8.2) | 5.2 ± 0.3 (3.7–6.9) | 5.8 ± 0.4* (4.4–8.6) |
| Type II | 4.8 ± 0.3 (3.9–7.0) | 5.6 ± 0.4* (4.3–8.0) | 4.9 ± 0.3 (3.4–6.0) | 5.5 ± 0.3* (4.4–7.5) |
Data are mean ± SEM, and range in parentheses, before (Pretest) and after (Posttest) 5 weeks training in normobaric normoxia (TRNOR, n = 10) or hypoxia (TRHYP, FiO2: 12.3%, n = 10) while subjects lived in normobaric hypoxia with simulated altitudes gradually increasing from 2,000 m to 3,250 m. See Methods for further details.
*
P < 0.05 compared to the pretest.