I thought the group would enjoy this:
Relative activity of hip and knee extensors in sprinting –
Implications for training
Klaus Wiemann and Gunter Tidow
New Studies in Athletics
10(1): 29-49, 1995
2.2 The search for a synergist of the gluteus maximus muscle
As forward acceleration in sprinting is obviously produced by hip extension rather than knee extension (Waser 1985; Lemaire & Robertson. Power in Sprinting. Track and Field Journal. 35: 13-17, 1989, Ae et al. (The men’s 100 metres. New Studies in Athletics. 7(1): 47-52. 1992), it seems plausible to suppose that the strongest hip extensor, namely the gluteus maximus (GM), takes a major part in this extension. However, there are some doubts concerning this supposition, because the GM does not function only as a hip extensor; it also rotates the thigh outward, especially when the hip joint is extended. This could cause a backward rotation of the pelvis on the side of the free leg during the support phase, which might hinder the long forward swing of the free leg. Furthermore, the GM also has an abducting effect on the leg – especially in the case of the angled hip joint. This could have a negative effect on the straight movement of the support leg from front to back. However, outward rotation and abduction would not be of any consequence in the sprint, if another muscle could not act together with the GM during the hip extension and also to neutralize the abducting effect of the GM. This task could be taken over by the m. adductor magnus (AM), especially by its superficial part, which has its origin exactly at the ischial bone, medially beside the origin of the hamstrings and inserts to the medial epicondyle.
The following aspects support the supposition that the superficial part of the AM contributes to the production of the sprint movements and can therefore be considered as a synergist of the GM.
• The direction and mass of the AM give reason to assume that the AM – especially in the case of the bent hip joint – is a strong hip extensor and not so much an adductor. The adducting effect of the AM is especially minimal when, on the sagittal plane, the thigh is vertically below the hip joint. However, while the hip of the support leg is being extended, the balance out the abduction of the GM.
• Both the superficial part of the AM and the hamstrings are supplied by the same nerve (obturator nerve), while the deeper part of the AM is supplied by a different nerve (ischiadic nerve). This fact alone could lead to the conclusion that the superficial part of the AM – especially during movement phases which are characterized by a bent hip joint – fulfils a task which can rather be compared with that of the hamstrings, namely hip extension.
• In almost all bent positions of the hip the AM rotates the high inward and thus can counterbalance the outward rotation of the GM.
Unfortunately, in the electromyographic investigations of the sprint conducted so far, the adductors have only been dealt with in passing. Ralph Mann (Biomechanical analysis of sprinting. Track Technique. 94: 3000-3003, 1986) examined only the comparably weak m. adductor longus and McClay et al. (Muscle activity in running. Biomechanics of Distance Running. Chapter 6: 165-186, 1990) give a report on the findings of Mann & Hagy (Running, jogging and walking: A comparative electromyographic and biomechanical study. Bateman, JE/Trott, A.: The foot and the ankle. pp. 167-175, 1980), according to which the adductors (without making a specific difference between the individual adductor muscles) are active during the whole sprint cycle.