how important is the hip flexor in all-out sprinting.
HIP FLEXOR
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Participant
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KeymasterYou couldn't do without it but as Flow said I wouldn't devote any specific training to it because sprinting alone makes it strong enough to not be a limiting factor in almost all cases.
ELITETRACK Founder
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Participant
but is it important enough to do maybe one exercise twice a week to help strengthen them. bc i've been told that my knees dont come up high enough ( to about 90) so i figured doing a couple dozen reps of stationary high knees would help. is that a good idea?
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Participant
but is it important enough to do maybe one exercise twice a week to help strengthen them. bc i've been told that my knees dont come up high enough ( to about 90) so i figured doing a couple dozen reps of stationary high knees would help. is that a good idea?
Hip flexor (knee height) has a lot to do with pelvis position. Stand up and stick your butt out, raise your knee. Stand up and push your pelvis out (squeeze your glutes / thrust), raise your knee. You will see what I mean. Knee should come up much higher on the 2nd method. Hip flexor strength usually isn't the issue.
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Participant
working your hipflexor could be detrimental in your situation. it could shorten or just foster the already given unbalance which causes the anterior pelvic tilt and in that way hinder your knee-up motion even more.
to get a feeling of how awesome sprinting with high knees is you could try squeezing your abs during maxV running. thats how i did it the first times : ) -
Participant
You do not need to do any specific work on the hip flexor muscles. All the sprinting and plyometric work you do is all the work you need.
Agreeing with mortac, knee height is partially dependent on pelvic tilt. A posterior pelvic tilt allows the thigh to be lifted higher during running. Strong abdominal muscles help to keep the pelvis tilted posteriorly, as those muscle are attached to the anterior portion of the pelvic girdle.
Another thing that affects knee lift is force production against the ground. When you run, you have to exert "x" amount of force against the ground in order to move you forward. Running slowly needs less force that running fast, or sprinting. At the same time, running slowly has much less knee lift than sprinting. Now, I am NOT saying you should stomp the track with every step, but increasing force against the ground helps with knee lift, when done properly.
Think about this just now, and mike and other, correct me of I'm off on this one, but the stretch-shortening cycle should play a role in this as well. Stretch-shortening cycle states that when a muscle is quickly stretched, it will respond with a fast, very powerful, contraction. During sprinting there is complete extention of all 3 joints of the leg, hip knee and ankle. When this happens right at toe off, there is a great deal of stretch in the hip flexor muscles. This increased stretch stimulates the body to automatically contract the hip flexors, thus lifting the knee higher.
I'd like comments on that last part. Makes sense to me theoretically, but I'm wondering if anyone knows if that's really what happens or now.
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Participant
While I am not a biomechanist, CF told me once that with correct posture and mechanics the majority of hip flexor activity is elastic (reflex). He said
'voluntary' hip flexor contraction occurs only at the very top of the motion (last few inches of knee ascent).Edit: I am talking about top speed mechanics here, not accel.
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Participant
While I am not a biomechanist, CF told me once that with correct posture and mechanics the majority of hip flexor activity is elastic (reflex). He said
'voluntary' hip flexor contraction occurs only at the very top of the motion (last few inches of knee ascent).Edit: I am talking about top speed mechanics here, not accel.
Who is CF???? dont drills also help to work on dat?
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Keymaster
I pretty much agree. I definitely think the initial movement of the swing leg is reflexive / elastic but the statement is a little overstated. I'd guestimate that the last 60 degrees of movement (total hip movement is about 120) is not elastic in nature. The thigh is just too heavy and the moment arm too great for the entire thing to be an elastic movement. This isn't to say that it isn't reflexive though (they're not always the same thing). The body has an extension reflex that tends to cause the flexion of one limb when the other is extended.
ELITETRACK Founder
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Participant
[quote author="mortac8" date="1162999372"]
While I am not a biomechanist, CF told me once that with correct posture and mechanics the majority of hip flexor activity is elastic (reflex). He said
'voluntary' hip flexor contraction occurs only at the very top of the motion (last few inches of knee ascent).Edit: I am talking about top speed mechanics here, not accel.
Who is CF???? dont drills also help to work on dat?
[/quote]he was the king of england back in the 80's.
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Participant
Charlie Francis, coached Ben Johnson, one of the greatest minds ever on the topic of sprinting. check his website out and check out the forum, its amazing.
as for hip flexor exercises, A and B skips are very beneficial and will get you used to lifting you knees really high, not to mention that the skips give you increased ROM. resistance exercises for the hip flexors are pointless though, stick to compound lifts like squats and deadlifts.
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Participant
thanx for all the feedback
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