If you want to keep the same set of knees for your entire life, you must keep them healthy. Exercise is how you keep your knees, joints, muscles, bones, tendons, ligaments, and every other component of your musculoskeletal system healthy. “How” you exercise matters. Exercise has many benefits but can also have risks depending on “how” you exercise.
IFPA Certified Personal Trainers all know the IFPA’s primary, number one rule is “do not harm”!
A personal trainer that sacrifices safety in an attempt to increase effectiveness, is in violation of “do no harm”.
The IFPA Personal Trainer Certification Course provides very detailed “Safety Guidelines” for all exercise movements, including “Knee Safety Guidelines”, some of which are:
- Do not exceed Knee-Toe-Line
- Do not exceed Knee-Hip-Line.
- Do not bounce at the bottom of an exercise
- Do not twist the femur (thigh bone) in relation to the tibia (shin bone)
- Do not put anything under the heel (including “High Heeled Shoes”) during Squatting movements
While it is essential for all Personal Trainers to read, study, and learn the treatment, care and prevention issues surrounding all the injuries that result from inappropriate physical activity or lack of activity, the limitations of this forum will require that I only focus on one of the most controversial of the Knee Safety Guidelines: “Do not exceed Knee-Toe-Line”.
Understand that the Knee Joint is incredibly well designed. It can flex over 150 degrees front-to-back, another 3 or 4 degrees side-to-side and rotate over 60 degrees, all at the same time if required to do so.
Unfortunately, this vast range of motion also creates the “instability” that can lead to injuries. If the knee extends more than 3 inches across, in any direction, it is too much! This exceeds its tolerable limits, resulting in injury.
The Knee Safety Guidelines including “Do Not Exceed Knee-Toe-Line”, were developed to ensure the knee stays within the tolerable limits. Personal Trainers should use common sense. An “Unloaded” Knee can tolerate more than a “Loaded” Knee. This is why over 25% of sports injuries and over 75% of all sports surgeries, are caused by some combination of loading and/or instability.
This is understandable, particularly when you realize the biomechanics of a movement like the Squat. At knees bent at 90 degrees, UNLOADED, the stress on the back of the kneecap is about 7.5 times your body weight which can be over 1,000 pounds of force per square inch. Then, in a LOADED Squat, multiply the weight you are using by 7.5 and add it to your bodyweight times 7.5!!! If you exceed Knee-Hip-Line, the stress on the knee increases even more. The deeper the Squat, the greater the pressure in the knee.
Exceeding Knee-Toe-Line also places pressure on the back of the kneecap to bursas and cartilage. As you knee bends, the back of the knee cap comes in contact with the femur (thigh bone), but never the tibia (shin bone).
This pressure increases the more you:
(1) exceed Knee-Toe-Line
(2) the deeper you bend the knee
(3) the greater the load you use
All of the above can lead to “Chondromalacia” and/or “Bursitis”.
Chondro means “cartilage” and malacia means “wear”. The wear and tear on the knee cartilage does not immediately register as pain. For that matter, many chronic injuries don’t register pain since most joints in your body have less pain sensing mechanisms. A lot of damage can be created below your pain threshold.
Similar to Chondromalacia, Bursitis is a chronic injury that sneaks up on you. Bursas are envelopes of paper thin, slippery tissue, that act as friction reducers. You have Bursas that try to reduce the friction between the back of the kneecap and the femur. When you increase the load, exceed Knee-Toe-Line and bend the knees deeper into the Squat, the Bursas can be damaged. They can become irritated and then inflamed, reducing their effectiveness, leading to more damage and eventually: PAIN!
You should also consider the damage that can occur if your kneecap comes off-its-track. It does not take much. Exceeding Knee-Toe-Line and/or violating one or more of the other Knee Safety Guidelines may cause the kneecap to come off its track.
Once the knee is damaged due to violating Knee-Toe-Line or any other Knee Safety Guidelines, fluids are produced by the knee in an effort to reduce friction. However, this can lead to the exact opposite effective and creates an environment that can produce Baker’s Cysts or Meniscus Cysts.
You also have 7 different ligaments in and around the knee capsule. The Anterior Cruciate Ligament (ACL) tear may be the single most common acute knee injury. No one knows for sure, as it’s just in the last 20 years or so that tests have been developed to make a dependable and accurate diagnosis.
ACL tears are classified as Acute Injuries, though many believe that repeatedly violating the Knee Safety Guidelines may damage the ACL enough to make it susceptible to the event that causes the ACL tear. Most of the other 6 knee ligament tears are created through an acute event, but once again, consider if Knee Safety Guideline violations create weakness in the ligament that leads to the acute event. Though not scientifically valid evidence, consider that strength trained youths experience far less injuries to the ligaments and all other tissues than new strength trained youths.
You should also be aware there are some who disagree that exceeding Knee-Toe-Line can cause injury. Since I prefer to keep the same set of knees for the rest of my life, and I wish, hope and pray for everyone in the IFPA, their personal training clients and everyone I care about to do the same, I will continue to stress this and all other Safety Guidelines.
The biggest complaint seems to be that keeping your knees behind the Knee-Toe-Line during the Squat causes the back to move downward leading to dangerous levels of stress to the back. All IFPA Personal Trainers should know that the Key Teaching Points are designed to protect the entire body, including the back. Exceeding the Knee-Toe-Line places no more stress on the back than the direction you part your hair! You have specific Key Teaching Points to protect the back detailed in your IFPA Personal Trainer Textbook: “The Book on Personal Training”!
I ask you ALL to please continue to adhere to everything you have learned to become and IFPA Certified Personal Trainer and seek advanced knowledge, skills, and abilities to expand your Scope of Practice.
Much of what has been discussed here is detailed in “Anybody’s Sports Medicine Book” by Dr. James Garrick (One of the World’s Best Orthopedic Surgeons) Dr. Peter Radetsky, and Dr. Jim Bell, CEO, IFPA.
All of us at the IFPA wish you the best of luck and safe and effective personal training careers.
Dr. Jim Bell