(800) 545-4772
Sign In
Should You Lock Your Joints When You Stretch?

Should You Lock Your Joints When You Stretch?

Reading Time: 3 minutes 36 seconds


DATE: 2019-08-15

To lock the joint or not to lock the joint, that is the question. Have you ever had a client ask you this? Do you know what to tell them? Let's make sure we have a basic understanding of joints and which joint raises this question the most. This will help provide groundwork so you can guide your clients through safe and effective stretches.

The Basics of Joints

Joints are an integral part of the human body. There are over 300 of them. And while there are a variety of different types of joints throughout the body, they're essentially a place where two bones come together. The joint's purpose is to help stabilize the body. Many joints also play a huge role in helping the body move properly. To get a better understanding of this, let's review some of the basics.

Joints are typically made up of:

  • Ligaments - connective tissue that connects a bone to another bone

  • Tendons - connective tissue that connects surrounding muscle to the bone

  • Cartilage - tissue that helps protect the bones from rubbing together

  • Additional fluid and padding - helps lubricate and protect the joints

Common joints:

  • Knee - where the lower leg and upper leg come together

  • Shoulder - where the upper arm and the torso come together

  • Elbow - where the lower arm and upper arm come together

  • Ankle - here the lower leg and foot come together

  • Hip - where the upper leg and pelvic region come together

What is the Most Common Joint Clients Lock While Stretching?

Of the 300+ joints in the human body, the most common joint clients lock is the knee. And this is especially the case when they're stretching their hamstrings. This is a body part we all use a lot. So, let's make sure we understand how this part of the body is put together and what happens when we lock it.

Bones of the Knee

  • Femur - thigh bone

  • Patella - kneecap

  • Tibia - shin bone

  • Fibula - secondary smaller bone next to shin bone

Ligaments of the Knee:

  • Anterior Cruciate Ligament (ACL) - prevents the thigh bone for sliding backward on the shin bone

  • Posterior Cruciate Ligament (PCL) - prevents the thigh bone from sliding forward on the shine bone

  • Medial and Lateral Collateral Ligaments (MCL and LCL) - prevents the thigh bone from sliding side to side on the shin bone

Hamstring Muscles

The hamstrings are made up of a group of three muscles in the back of the upper leg. They are attached on the back side of the thigh starting near the sits bones (near the bottom of the pelvis) and then stretch to the inside and outside of the lower leg just below the knee.

The hamstrings help bend the knee, extend the hip, and slightly help with rotations of the knee. These are major movements in almost every sport and also key movements in common daily tasks like walking or running.

What Happens When the Knee is Locked?

For purposes of this article, the verbal cue to "lock the joint" or more commonly "lock your knee" means to straighten the leg and press the knee back as far as possible so that there is no bend in the knee.

Back of the Knee Joint

If we are consistently pressing our kneecap back, it is possible to cause too much stretch in the back of the knee and the surrounding ligaments that hold the knee in place. Although cartilage and tendons should have a bit of elasticity, their primary purpose is to hold the knee in place and make sure it doesn't move too far in any direction that it shouldn't.

Front of the Knee Joint

The forced compression can also cause stress on the front of the knee. The cushioning and cartilage that is there to protect the knee, may become damaged. If this cushion is damaged, clients can experience a variety of issues:

  • Pain

  • Stiffness

  • Swelling

  • Injury

  • Limited range of motion or inability to move properly

  • Arthritis

Ultimately, one of your main goals as a trainer is to help clients move, correctly and without pain, for as many years of their life as possible.

For more information on knee pain and how to help your clients, check out these two articles:


The tendons and ligaments in the body play an important role in keeping the joints in the body stable and helping them move through the proper range of motion. We want our clients to be able to move well and move in several directions but excessive motion of the joints, in any direction, can lead to injury.

Locking the knees when stretching could cause damage to the knee joint. Helping educate your clients on how to protect their joints will help your clients move better now but also help keep them moving well for years to come.

If you're interested in learning more about how joints, muscles, and bones should all work together and helping your clients move and perform properly. Check out ISSA's Corrective Exercise course.

Sign Up & Stay Connected

Receive $50 off your purchase today!

I consent to being contacted by ISSA.