Table 5.
Summary of Published Data on Fiber csa and Contractile Properties of Human VL Muscle Fibers
| Age (N) | CSA | Normalized Force | Velocity | Power | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Young | Old | Activity Level | Sex | Muscle | I | IIa | I | IIa | I | IIa | I | IIa | References |
| 30±2 (7) | 73±2 (7) | Inactive | M | VL | −22% | −12% | −22% | −16% | ↓ | ↓ | N/A | N/A | 11 |
| 32 (6) | 66 (6) | Inactive | M | VL | = | = | −25% | −33% | −23% | −22% | N/A | N/A | 13 |
| 37 (7) | 74 (12) | Inactive | M | VL | = | = | −28% | −31% | N/A | N/A | N/A | N/A | 14 |
| 20−43 (7) | 65–85 (17) | N/A | M | VL | = | −29% | −23% | −14% | −17% | −11% | N/A | N/A | 59 |
| 20−43 (6) | 65–85 (5) | F | = | = | −20% | −25% | −20% | −30% | N/A | N/A | |||
| 25−31 (4) | 73–81 (2) | Combined | M | VL | = | −28% | = | −28% | = | = | N/A | N/A | 16 |
| 25±3 (33) | 76±4 (30) | Inactive | N/A | VL | 11% | −24% | = | = | ↓ | = | ↓ | ↓ | 60 |
| 37±3 (7) | 74±6 (7) | Inactive | M | VL | N/A | /A | N/A | N/A | = | −17% | N/A | N/A | 15 |
| 27±3 (12) | 72±4 (12) | F | N/A | N/A | N/A | N/A | −7% | = | N/A | N/A | |||
| 30±4 (5) | 73±3 (3) | Inactive | N/A | VL | N/A | N/A | ↓ | ↓ | ↓ | ↓ | N/A | N/A | 24 |
| 73±3 (3) | Trained | N/A | N/A | N/A | = | = | = | = | N/A | N/A | |||
| 21±2 (9) | 85±1 (6) | Inactive | F | VL | = | = | = | = | = | = | = | = | 21 |
| 25±1 (6) | 80±4 (6) | Inactive | M | VL | = | = | = | 12% | = | = | = | = | 20 |
| 25±1 (6) | 78±2 (6) | F | 13% | −17% | = | = | = | = | = | = | |||
| 18−33 (8) | 53−77 (9) | Sprinter | M | VL | −26% | −36% | = | = | −24% | = | N/A | N/A | 18 |
| 23±1 (9) | 67±2 (8) | Inactive | M | VL | = | = | = | = | N/A | N/A | N/A | N/A | 50 |
| 27±3 (7) | 74±4 (7) | Inactive | F | VL | = | = | = | = | N/A | N/A | N/A | N/A | 19 |
Notes: Values represent percent difference between young and old participants; CSA = fiber cross-sectional area; F = female; M = male; N = number of participants; N/A = not available data; VL = vastus lateralis; =, no statistical difference between young and old; ↓ = reported significant decrease in old compared with young but data not provided;