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Targeting Contractile Tissue

Targeting Contractile Tissue

Lacking Results in Rehab? You may not be targeting the contractile tissue of your muscles…

Mike has had Achilles pain for 6 months and has lost significant power since his injury. He continues to do his prescribed eccentric heel raises (the standard tendon rehab protocol that has been in vogue for years). They may have helped for a time, but his strength has plateaued, his power has not returned, and it still hurts when he plays.

Targeting Contractile Tissue   Targeting Contractile Tissue

Note the heel wrinkles as he does a double leg heel raise (green arrows) vs the lack of heel wrinkles as his foot lifts (red arrow)

Rudy has been working on his finger strength for rock climbing by squat lifting a weight off the ground with his fingertips. He’s 50% stronger in the month since he started, but now he has more finger pain in the middle of his pad, when climbing, and it even hurts to touch it.

Targeting Contractile Tissue   Targeting Contractile Tissue

Lifting 140 lbs off a 20mm edge – Note the shoulder lifts and the hand opens to perform the lift


Kat has been speeding through her resisted side-steps exercise.  She does them every single day, as quickly as possible, to fit into her busy schedule of carting her kiddo Jaden around.  However, she hasn’t noticed any improvement in her hip pain.

Targeting Contractile Tissue   Targeting Contractile Tissue

Note: The knees point out to start (on the outside of her feet) and end pointing in (on the inside of her feet)

What do these three have in common?

Despite working hard and consistently for months, these 3 have only been training their muscles’ Connective Tissues or Non Contractile Force Generators. Meaning, they have been targeting structures that don’t actively contract, but can still generate force.

Targeting Contractile TissueLet’s break this down on a muscular level.  The innermost unit of a muscle is a “muscle fiber” (and this is where all of the active muscle force is generated). In our purposes today, muscle fibers are the only Contractile Force Generators. These fibers will shorten the muscle when contracted.   Each muscle fiber is wrapped in connective tissue, and a group of muscle fibers are wrapped in progressively larger bundles of connective tissue, that continue on as a tendon on either end of the muscle to make up a “fascicle”. And groups of fascicles are then wrapped by more connective tissue.  That is 3 layers of connective tissue, for 1 layer of contractile tissue. Even though the connective tissue doesn’t contract, it will still generate force.  The noncontractile connective tissue has an elastic component to it, and stores up the energy of the contractile tissue (much like pulling a spring back). As the connective tissue reaches its limit, it recoils, adding to the contractile muscle fibers force generation. The connective tissue is a powerful Noncontractile Force Generator

Noncontractile Force Generators are the reason Ant, a 6’4” guard, can jump over his taller team mates, hit his head on the rim, and block a game-tying lay-up:

Targeting Contractile Tissue


Targeting Contractile Tissue

Noncontractile force generators participate most when the muscle is elongating under tension (like Mike’s Eccentric heel raises) or when moving quickly (Kat’s side-step exercises).  Friction between structures will also become a force generator (such as Rudy’s finger flexor tendons that are pulled into the pulley, or even the chalked-skin on the hold).

This picture of the A2 pulley that holds the finger flexor tendons into the bone. As a finger “resists opening” the tendon is pulled into the pulley, creates more friction, and contributes to the total force.  However, if you are actively closing your fingers around a pliable object, the friction generated may actually subtract from the total force.

Ligaments can also generate some force when they are taut at end range (and provide a passive stability). Friction between two bones (your knee cap being pushed into the femur as you step down) ill also provide force. Relying on noncontractile force generators is extremely energy efficient;  it takes no energy to perform.  Brains like to conserve energy, and these movements may become your chosen movement pattern, to no conscious choice of your own. 

The problem with that?

Noncontractile tissue has a terrible blood supply (that is why it is white while muscles are red), and therefore heals much more slowly. So, when connective tissue is over stressed time after time, it never has time to heal.  If all your rehab program is doing is targeting the connective tissue, you may be adding more fuel to the fire.  You also aren’t getting to the root of the problem which is muscle weakness.

The Solution?

Mike needs to start focusing on concentric exercise by lifting his body weight up with one foot. He needs to make sure he gets some wrinkles in the back of his heel as soon as he starts moving, keeps his toes relaxed, and his ankle from deviating. There are 5 other muscles that will contribute to a heel raise other than the gastroc/soleus that attach into the achilles tendon. If toes move, the ankle deviates, or wrinkles don’t form in the back of the heel, one of those other 5 muscles is taking over. Focusing on lifting the heel is key to isolating the gastroc/soleus muscles and achilles tendon. Lifting the heel and forming the wrinkles will finally allow him to start improving Achilles strength. Eventually, he should add additional weight to progress the strength, and then add speed to progress the power.

Targeting Contractile Tissue Targeting Contractile Tissue

Note the heel wrinkles throughout the heel lift. This indicates an isolated gastroc/soleus contraction (without the help of the other five plantar flexors).


Rudy needs to drop the weight, by at least half, and lift the weight off of the ground by curling his fingers, without moving his shoulder or legs. This will reduce compression and friction of his finger flexor tendon into the pulley while actually strengthening the muscle, rather than the tendon-pulley interface.

Targeting Contractile Tissue Targeting Contractile Tissue Targeting Contractile Tissue

Note the Shoulders, Hips and Knees (red arrows) remain still, as just the fingers curl and lift


Kat, just needs to slow down. By moving as slowly as possible three things will happen:

  1. She will get fatigued more quickly, since she is actually expending energy rather than relying on the stored energy of the tendons.
  2. Her side steps will be smaller since she is no longer relying on her tendon to generate some of the force.
  3. She can still get her exercises finished by doing fewer, more difficult reps without adding more time to her routine.

Targeting Contractile Tissue Targeting Contractile Tissue

Note her stepping distance has lessened, and her knees remain on the outside of her hip to ankle line

Kat, Rudy and Mike  will all start noticing actual strength gains, and their pain will go away as they are able to start moving with more support from contractile tissue, allowing the non-contractile connective tissue to heal.

For assistance on your programing, we at ALTA can help if you haven’t yet met your goals. Just send us a text at 303-444-8707 to get started.

P.S. Give yourself a gold star for the day if you recognized the starting lineup of the Minnesota Timberwolves used throughout the blog. And enjoy more mayhem from the Ant Man: Anthony Edwards with the most insane poster dunk ever on John Collins 🤯


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