Table 4.
Summary of the adaptations in skeletal muscle structure and function to resistance training at the tissue, cellular and subcellular/molecular levels
| Structure | Function | ||
|---|---|---|---|
| Tissue | |||
| Leg muscle mass | ↔ | Knee extensor torque | ↑ |
| Cellular | |||
| Single fibre cross-sectional area | ↔ | Single fibre isometric tension | ↔ |
| Adjusted single fibre isometric tension # | ↑ | ||
| Subcellular/molecular | |||
| Myofibril fractional area | ↓ | Strongly bound cross-bridges (B and C) | ↓ |
| Thick-to-thin filament ratio | ↔ | Myosin attachment time (ton) | ↓* |
| A-band length | ↑** | Rate of force production (2πb) | ↑↓† |
| Myofilament stiffness (A and k) | ↑↓‡ | ||
The directionality of change in each variable is denoted by arrows, with horizontal, double-ended arrows indicating no change. #, single fibre data in which the post-training tension was adjusted for training-induced reductions in myofibril fractional area; *, training effect specific to HF patients in MHC IIA fibres; **, statistical trend (P = 0.07) towards training effect; †, statistical trend (P = 0.06) towards group × training interaction effects in MHC IIA fibres; ‡, statistical trend (MHC I; P = 0.06) or significant (MHC IIA) effect of training for k.