Table 3.
Myofiber Force–Velocity Relationship
| Peak Power | ||||||
|---|---|---|---|---|---|---|
| MHC | No. of fibers | V max (FL/s) | a/P o | µN × FL/s | W/L | |
| Y | IIa | 44 | 4.89±0.20 | 0.039±0.00 | 119±9 | 14.5±0.5 |
| Hybrid | 11 | 5.29±0.74 | 0.040±0.00 | 109±15 | 15.0±1.3 | |
| O | IIa | 47 | 4.52±0.22 | 0.039±0.00 | 71±4* | 11.5±0.4* |
| Hybrid | 14 | 4.42±0.55 | 0.037±0.00 | 71±11* | 11.2±1.3* | |
Notes: Values are mean ± SE. MHC = myosin heavy chain isoform; No. of fibers = number of fibers obtained from vastus lateralis muscle from four monkeys for each age group; O = old monkeys; Y = young monkeys; V max = y-intercept of force–velocity relationship; a/P o = unitless parameter describing the curvature of the relationship. *—indicates a significant difference between age groups (p < .05) analyzed by two-way analysis of variance based on number of single fibers.