Table III.
Electromyographic activity of the glenohumeral muscles during spiking (% MVIC, mean ± SD)
| Muscle | Phase |
||||
|---|---|---|---|---|---|
| Wind-up | Cocking | Acceleration | Deceleration | Follow-through | |
| Anterior deltoid | |||||
| Standard position | 53 ± 48∗ | 64 ± 43 | 43 ± 33† | 50 ± 28 | 42 ± 19 |
| Posterior position | 57 ± 18 | 63 ± 40 | 74 ± 72† | 58 ± 27 | 49 ± 42 |
| Medial position | 28 ± 17 | 52 ± 46 | 53 ± 50 | 67 ± 41 | 35 ± 16 |
| Lateral position | 25 ± 14∗ | 58 ± 50 | 40 ± 50 | 52 ± 31 | 33 ± 23 |
| P value | .031 | – | .041 | – | – |
| Middle deltoid | |||||
| Standard position | 29 ± 15 | 37 ± 22 | 44 ± 40 | 37 ± 24∗ | 33 ± 13 |
| Posterior position | 32 ± 18 | 47 ± 45 | 60 ± 33 | 40 ± 29 | 35 ± 23 |
| Medial position | 28 ± 15 | 43 ± 19 | 33 ± 41 | 34 ± 21 | 26 ± 24 |
| Lateral position | 26 ± 15 | 49 ± 28 | 50 ± 32 | 66 ± 31∗ | 39 ± 19 |
| P value | – | – | – | .005 | – |
| Posterior deltoid | |||||
| Standard position | 6 ± 4 | 7 ± 6 | 50 ± 36∗ | 21 ± 14 | 18 ± 13 |
| Posterior position | 9 ± 10 | 12 ± 7 | 55 ± 35 | 18 ± 11 | 19 ± 18 |
| Medial position | 9 ± 8 | 12 ± 9 | 21 ± 15 | 21 ± 18 | 17 ± 24 |
| Lateral position | 8 ± 7 | 14 ± 14 | 80 ± 41∗ | 39 ± 24 | 27 ± 17 |
| P value | – | – | .04 | – | – |
| Infraspinatus | |||||
| Standard position | 27 ± 19 | 28 ± 18 | 46 ± 34 | 62 ± 34† | 55 ± 42∗ |
| Posterior position | 27 ± 13 | 29 ± 18 | 44 ± 12 | 44 ± 18† | 46 ± 21 |
| Medial position | 20 ± 14 | 22 ± 23 | 33 ± 12 | 57 ± 29 | 42 ± 28 |
| Lateral position | 19 ± 12 | 27 ± 24 | 62 ± 40 | 48 ± 31 | 36 ± 23∗ |
| P value | – | – | – | .043 | .019 |
| Pectoralis major | |||||
| Standard position | 28 ± 53 | 13 ± 17 | 68 ± 33† | 20 ± 28 | 18 ± 25 |
| Posterior position | 8 ± 1 | 14 ± 9 | 44 ± 29† | 11 ± 8 | 11 ± 10 |
| Medial position | 9 ± 8 | 9 ± 14 | 53 ± 30 | 26 ± 31 | 26 ± 34 |
| Lateral position | 7 ± 7 | 13 ± 20 | 69 ± 27 | 26 ± 31 | 15 ± 17 |
| P value | – | – | .007 | – | – |
| Teres major | |||||
| Standard position | 25 ± 41 | 29 ± 41‡ | 76 ± 55 | 29 ± 36 | 25 ± 35 |
| Posterior position | 11 ± 12 | 13 ± 13 | 51 ± 19 | 29 ± 52 | 16 ± 14 |
| Medial position | 7 ± 8 | 8 ± 7‡ | 64 ± 29 | 29 ± 29 | 24 ± 34 |
| Lateral position | 6 ± 5 | 9 ± 7 | 72 ± 30 | 19 ± 17 | 20 ± 20 |
| P value | – | .05 | – | – | – |
MVIC, maximal voluntary isometric contraction; SD, standard deviation.
∗
Significant difference between the standard position and the lateral position (P < .05).
†
Significant difference between the standard position and the posterior position (P < .05).
‡
Significant difference between the standard position and the medial position (P < .05).