Approximate contributions to impact racquet velocity (%)
| Power serve | Topspin forehand (forward direction) | |
|---|---|---|
| Shoulder | 10 | 15 |
| Upper arm | ||
| Horizontal flexion | 15 | 25 |
| Internal rotation | 40 | 40 |
| Forearm | ||
| Extension | Negligible | Negligible |
| Pronation | 5 | Negligible |
| Hand | ||
| Flexion (palm/ulnar) | 30 | – |
| Flexion (palmar/radial) | – | 20 |