The muscles along the back of the thigh, the hamstring group, can be a frustratingly tight muscle. No matter how much stretching you do, they always feel tight. And when you try to strengthen them, the hamstrings tend to cramp up. Here's how to lengthen those tight muscles and make them strong at the same time!

How To Lengthen Your Hamstrings

Hamstring tightness is often a combination of several factors

  1. Increased scatic nerve tension: if the body does not feel comfortable enough to let the sciatic nerve move, the hamstring muscles tighten up to protect the nerve. To fix the hamstring tension, nerve flossing and gliding techniques are necessary to improve the sciatic nerve mobility
  2. Weakness in a stretched position: oftentimes the hamstring muscles are strengthened in a 'bent knee' position. The muscle becomes strong in the middle of it's range of motion but weak in the stretched position. Strengthening (especially eccentric) exercises are the key to address this component of hamstring tightness.
  3. Postural effects: if we sit or sleep with our knees in a bent position, the hamstring spends the majority of it's time in a relaxed and "shortened" position. The muscle & nervous system normalize this muscle position. Whenever the knee is straightened, the nervous system isn't comfortable with this 'new position' and resists it. 


Why the Anatomy of the Hamstring Matters

hamstring muscles


To create flexible and strong hamstrings, it is important to understand their anatomy. The medial (inner) and lateral (outer) hamstring muscles originate on the ischial tuberosity at the back of the pelvis and extend down the back of the thigh to attach to the top of the calf. They function as a muscle that bends the knee as well as a muscle that can pull the hip backwards. They act to stabilize the knee and control hip & knee movements when walking, standing & running.  Photo source.



sciatic nerve mobilityBetween the medial & lateral hamstring, the sciatic nerve runs from the pelvis to lower leg. The sciatic nerve can be a vulnerable or sensitive structure for a lot of people. Oftentimes the body will tighten the hamstrings to guard the sciatic nerve because your brain is afraid of letting the nerve move. If we are to get your hamstrings loose & flexible, we also want to consider your sciatic nerve mobility. Photo source

Sciatic Nerve Mobility Exercises

Sciatic nerve hypomobility is present in nearly every person with tight hamstrings. Somtimes the tension is so tight, a person will a light tingling/numbness in the leg when stretching the hamstrings. Nerve flossing or gliding exercises are the best way to improve sciatic nerve mobility and restore comfort with movement.

Flossing the sciatic nerve involves stretching top half of the nerve chain while relaxing the bottom half. Then stretch the bottom half of the nerve chain while relaxing the top. The sciatic nerve flossing can be done while sitting, laying down, standing or sitting. I like to incorporate slumping the body in the spine forward, and then stretching the hamstring and ankle & toesup to get a nice stretch all along the bottom of the foot. 

There are tons of great variations of sciatic nerve flossing exercises, but here is one of my favorites.



Keys to Hamstring Strengthening 

The majority of common gym hamstring exercises train the muscle to shorten. The technical term for this is a concentric contraction, which is where the proteins in the muscle fibers are moving from their neutral position into a more overlapped position. This gets the muscle very strong & efficient in a shortened position but not strong in a lengthened area. This can tend to make the hamstring muscle feel tighter. 

To develop healthy hamstrings, you want to do a mix of concentric (shortening) as well as eccentric (lengthening) strengthening to get the muscle fibers strong & good at contracting quickly, but also strong at being stretched and working at the same time.  


muscle structure***A note about muscle anatomy, for all muscles the individual muscle fibers are comprised of a sequence of overlapping proteins called actin and myosin. These are arranged in a train-car pattern. When a muscle fiber contracts, the amount of overlap of these proteins changes. When the proteins overlap more, it is termed a concentric muscle contraction. If the proteins that build the muscle fiber slide apart while the muscle is contracting, it is an eccentric muscle contraction. Eccentric strengthening exercises actually add more segments, or ‘train-cars’ to the muscle! This makes the muscle physically longer. Photo source


How To Lengthen Your Hamstrings with Strengthening

In your course of Physical Therapy at Creekside, we will assess and help you find the best hamstring exercises to meet your goals. We will also guide you in finding the right intensity and volume. In general however, the below exercises are a good place to start. 

  • Quick curls with a slow straightening of the knee is a straightforward place to start.  

  • Heel slide or eccentric bridges. You go up into a normal bridge and then slide your heels out away from your hips. This is a great way to get the hamstring muscle firing but the fibers sliding apart.  

  • Eccentric deadlift variations are also great options. Conventional deadlifts with slow lowering to the floor. Single leg RDLs and walking ‘ Death Marches’ are fantastic at isolating the hamstrings on a single leg.   

If the muscle is the culprit behind your tight or irritable hamstrings, strengthening it in a more stretched position can be a real game-changer in improving hamstring tightness and strength.  


Postural Changes to Loosen Your Hamstrings

It's important to give the body practice in stretching the hamstrings. Sit with your knees straight sometimes! Putting a small box under your desk to rest your feet on can make a big difference in how tight your legs feel by the end of the day. 



To fix tight hamstrings, we want to make sure that the  sciatic nerve is moving well. Nerve flossing and glide exercises are one of the best ways to improve nerve mobility. We want to strengthen the hamstring with both stretching (ecdentric) and shortening (concentric) exercises. 


Here at Creekside Physical Therapy & Rehabilitation we’re here to help you move at your best! Give us a call at 503-300-0690 or shoot us a message to get your hamstrings stronger and more flexible! 

Join The Conversation
Terry Taul 06/24/2023 8:29 AM
Have had sciatic nerve o left side of back down left leg. Need to know best way to stretch hamstring .
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swarna perera 09/17/2023 10:47 PM
chronic extreme tight hamstrings
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