Hamstrings and the Squat

[Scott Beall]

Hello Mr. Rippetoe! I'll be taking the Starting Strength certification in Denver May 18-20 and am looking forward to it! I intend on becoming a SSC based in Denver if I prove myself worthy.

I'm struggling with a question while reading "The Squat" chapter. On page 17 it is written, "Here the function of the hamstring muscles (attached to the tibia and to the ischial tuberosity of the pelvis), is primarily isometric, since they don't necessarily change length on the way down."

As I perform this with bodyweight I feel the stretch (or at least it feels like a stretch). Additionally, the hamstrings are a hip extensor, so wouldn't they need to be stretched (lengthened) first on the way to the bottom, then shortened on the way up as they assist in hip extension?

Now I understand that knee flexion occurring on the way down contributes to some "slack." But it still seems to me that the hamstrings lengthen on the way down.

How is it possible that the hamstrings do not elongate on the way down?

Also, in the quote above, the word "necessarily" is used. Are there some cases where the hamstrings elongate and others where they don't? If so, what situations would cause either case?

[Mark Rippetoe]

We spend about 10 minutes talking about this Saturday morning. Maybe we can pull out a video of that part of the lecture.

[John Petrizzo]

The stretch you are feeling on the way down could be coming from the adductor magnus as their proximal attachment is at the ischial tuberosity (the same proximal attachment as the hamstring muscles). This attachment site is what allows the adductor magnus to contribute to hip extension out of the bottom of the squat. Additionally, one of the reasons that we don't believe there is any significant change in hamstring length during the descent of the squat (in addition to your observation that the hips and knees are simultaneously flexing and thus the hamstrings are lengthening at their proximal attachment while simultaneously slacking at their distal attachments), is that they hamstrings do not seem to be affected much by delayed onset muscle soreness (DOMS) following squats whereas the adductors do. One of the things believed to cause DOMS is eccentric muscle actions. An eccentric muscle action is one in which the muscle lengthens under a load. If the hamstrings changed length to any significant degree during the descent, it would probably be more common for them to be affected by DOMS after training.

I hope that helps.

[Scott Beall]

Thank you for the explanation, John. And again, the book says the hamstrings don't necessarily change length on the way down, seemingly leaving open the possibility. If one's hamstrings were sore, would you imagine they are being lengthened in that specific situation?

[Mark Rippetoe]

You're probably doing a little goodmorning at the bottom of the squat.

[Mark Rippetoe]

Hamstrings and The Squat | Mark Rippetoe

[Scott Beall]

My Hamstrings currently do not get sore from the Squat. You are correct in your assumption though, I used to get sore Ham's in years past. And I know I was doing a Good Morning-Squat at the time (pride-before-the-fall kind of thinking at the time - I can't worry about strengthening my spinal erectors right now, I've got to lift this heavy-ass weight!).

For the time being, I'm coming at this purely from a theoretical perspective.

When we talk in person, I believe I'll have some reasonable points to contribute to the discussion.

[Scott Beall]

Mr. Bones (or whatever y'all call him), will be there, yes?

[Mark Rippetoe]

He always is.