Muscles are activated in several different ways. These include isotonic contractions (which provides for concentric and eccentric contracts) and isometric contractions.

Concentric contractions cause muscle fibers to shorten as they contract. This is the only contraction our bodies can create without other forces to counteract them. For example, our brains can only tell our arms’ biceps to shorten. Our brains can’t tell contractile muscle tissues to lengthen. This only occurs when another force (such as a weight on our hand or the contractions of our triceps) overpowers our biceps.

A concentric contraction is its opposite. This type of contraction causes muscle fibers to lengthen while they contract. It’s more difficult because the brain cannot tell our biceps muscles to lengthen as they contract. Our biceps try to contract concentrically, but another force overwhelms that effort. If you hold a dumbbell weighing 20 pounds in your hand and lower it slowly while straightening your arm, then your biceps will contract eccentrically to resist both the weight of the dumbbell and the force of gravity pressing down on it. As you lower the dumbbell, your biceps lengthen, but still contract to slow down the descent.

When two forces (internal or external) are exactly in opposition to each other, no movement is produced. It happens often in yoga when teachers give cues such as “without movement, squeeze your leg together” or “Hug muscles to bone.”

This is a huge simplification of complex neurology. Still, it’s important to understand that contracting muscles in the extended position will help teach your nervous system this is a “working” muscle length. This can create a lasting change in the tissue, allowing for more mobility.

If you want greater mobility in your legs, stretching them out and then activating them, creating an isometric contract of the hamstrings. You can also increase mobility by eccentrically contracting your hamstrings. These two actions will teach your nervousness that you need your hamstrings to work with this increased capacity. This will tell your nervous system it is safe and even smart to keep them in this extended capacity for a long time, and that’s while you are resting.

Increase your mobility by activating your hamstrings with these 4 traditional yoga stretches

Try these poses, but pay attention to the muscular tension.

ARDHA HANUMANASANA (HALF SPLITS)

This classic pose becomes a more active stretch with a few simple cues.

To Practice:

Begin on your hands and knees, with your shoulders roughly stacked over your wrists. Your hips should be roughly stacked over your knees.

Step forward with your right foot next to your thumb. You might want to put your hands on the blocks.

Keep your left hip over your left leg and flex your foot to the right.

As far as is comfortable, slide your right heel towards the top of the mat. Straighten your right leg to its maximum. Your hamstrings will be stretched in this position.

You can isometrically tighten your hamstrings by pressing your right foot firmly into the floor. Draw your right heel energetically back towards your pelvis. Draw your right sitting bone energetically toward your right heel to counter this. Scissor energetically your right heel toward your left knee without moving.

Continue to activate your hamstrings. You can either continue as you are or lengthen them further by bending your hips forward and folding your right leg over.

Hold the pose for several long, deep breaths before gently releasing it and changing sides.

UTTANASANA (STANDING FORWARD FOLD)

With a few minor modifications, this often practiced asana can be easily transformed into a more active stretch.

To Practice:

Start with mountain poses.

Spread your toes out wide and bury the edges of your foot into the mat.

As you inhale, raise your arms to the sky.

As you resist gravity, exhale as you hinge your hips. You can reach your hands alongside your ears or draw them to your heart as you fold. The latter will provide your hamstrings with the most resistance and load as you fold slowly forward.

Rest your hands on your legs or blocks after you have folded the paper as far as possible.

Stretch your legs straight and as far as you can comfortably so that your hamstrings will be stretched.

Spread your sitting bones apart and lean your hips forward. Press the back of your thighs while simultaneously shifting your weight to the balls of your foot.

Take a few deep breaths.

To increase the load on your hamstrings, place a block between your hands as you fold forward. This will add weight and resistance.

PARSVOTTANASANA (PYRAMID POSE)

The intense Hamstring Stretch can help you to create lasting changes in your hamstrings. You must “trick” the nervous system into firing your hamstrings at this extended position.

To Practice:

Start with the mountain pose.

Step back your right foot and slightly angle it to the right of your mat. To find stability, you can stagger your legs as much as possible from side to side.

Scissor both legs energetically toward each other. Straighten your legs as far as you can comfortably to lengthen your hamstrings.

You can isometrically tighten your hamstrings if you lift your left toe and plant your left heel into the ground. Reach your left heel towards the back of your mat without moving. Imagine a line of energy extending from your left heel’s outer edge to your outer hip and descending from your inner hip to your left heel. Imagine a wave of energy running through your left leg while you maintain the pose.