wheez: if you only want to maximize your strength in the abdominal region it is better not to use your hip flexors. if you isolate the abs, you can work them more intensly and longer. unlike compound (or multi-joint) exercises, isolation exercises (where you only work one muscle group) does not depend on the strength of the weakest muscle. also, with isolation exercises, you know that you are working a specific muscle, and without (or with a minimal amount) of assistance.
for example, if you were doing leg press on a machine (quads), how much you can lift would depend on how strong your quads are, and you could basically continue reps til your quads tire. However, if you were doing squats (multijoint exercise using lower back, quad, adductors, etc), the factor limiting how much you could lift wouldn't be the quads but would be the lower back, the weakest muscle. therefore, if you purely want to increase your quad strength, leg press is the way to go, because the quads are not only not limited by the strength of the lower back. this example might be a minor factor for abs (i'm not sure that the hip flexors are weaker than the abs), but this is definitely a major factor to consider for other muscles.
going back to the abs, involving the hips will prevent you from stimulating your abs to the fullest, since your are lifting X weight assisted by hip flexors as opposed to lifting X weight unassisted. If you are worried about functional strength, IMO you don't need to be. If you are doing grappling and balance drills, you will be working the hip flexors anyways, so if you are using hip flexors during ab exercises, all you are doing is preventing your abs from reaching their maximum strength. btw, i liked legendary abs also.
[Edited by yusul on 10-25-2000 at 03:41 PM]
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