Original Editor - Tarina van der Stockt
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The kinetic chain (sometimes called the kinematic chain) is an engineering concept used to describe human movement. It is used in a wide variety of clinical conditions, including musculoskeletal, sports medicine, neuro-rehabilitation as well as prosthetics and orthotics. 
The concept was introduced by Franz Reuleaux, a mechanical engineer, in 1875. He proposed that rigid, overlapping segments were connected via joints and this created a system whereby movement at one joint produced or affected movement at another joint in the kinetic link. 
In 1995, Dr. Arthur Steindler adapted Reuleaux’s theory and included the analysis of human movement, sport-specific activity patterns and exercise. He suggested that the extremities should rather be thought of as rigid, overlapping segments in series and he defined the kinetic chain as a “combination of several successively arranged joints constituting a complex motor unit.”
This series, or chains, can be open or closed. 
Open Kinetic Chain
Steindler defined an open kinetic chain as “a combination of successively arranged joints in which the terminal segments can move freely”. Thus the distal segment of the extremity is free to move in space, for example: waving a hand, moving the foot during the swing phase of gait, or doing a seated knee-extension. 
Characteristics of Open Kinetic Chain Exercises 
- Open kinetic chain exercises are typically characterized by a rotary stress pattern at the joint. For example, when doing a seated knee-extension the primary stress to the joint is rotation of the distal tibia on the proximal femur even though other accessory movements like rolling and translation occur.
- Open kinetic chain movements occur in one primary axis. During the seated knee-extension exercise, the motion primarily occurs in the sagittal plane.
- The number of simultaneously moving segments is typically limited to one. "One segment of the joint (i.e. femur) remains stationary during the knee-extension exercise, while the other segment that forms the joint (i.e. tibia) is mobile." This adds control to the exercise because of the stability of the stationary segment (i.e. femur).
- These types of exercises allow for more isolated muscle activation because less muscle co-contraction is used to perform the movement.
Closed Kinetic Chain
Steindler’s definition of a closed kinetic chain exercise is when the distal segment meets “considerable” external resistance that prohibits free movement. Therefore, it is a system where neither the proximal nor the distal segments can move. Movement at one segment in the closed chain produces movement at all the other joints in a predictable manner. For example, during a squat, the movement at the knee joint accompanies movement at the hip and ankle joints. 
Unfortunately, Steindler did not quantify the term “considerable” in his initial definition, this lead to confusion and controversy as to what is considered a true closed kinetic chain movement. True closed kinetic chain movement patterns never occur in the extremities except in isometric exercises where no movement occur. 
However, in clinical practice, the definition of a closed kinetic chain is when “resistance is placed through the distal aspect of the extremity and remains fixed to the extremity”. The best example of this is the standing squat because the feet remain fixed to the ground and the surface produces considerable resistance in response to the athlete’s body weight or added weight. 
Characteristics of Closed Kinetic Chain exercises: 
| Using the standing squat as an example - |
The Current Kinetic Chain Concept Challenged
- Some exercises are more difficult to classify as open or closed kinetic chain. Stair-climbing machines are one example, because the feet are each fixed to a pedal that is continuously moving during the exercise. The same with riding a bicycle, even though it is a closed system, researchers and clinicians do not classify this as a closed kinetic chain exercise. 
- In his blog titled The Problem with the Kinetic Chain, Mike Reinold challenges the idea of the kinetic chain in two ways. Firstly, not all links in the kinetic chain are equally important, so it's more important to think of it as a chain reaction rather than just a chain. "Take the hip as an example. Any tightness, weakness, or imbalance of the hip is going to have a large influence on the low back and knee, and a much less impact on joints the further away you get from the hip." Secondly, the kinetic chain needs to include the structures between each link (i.e. muscles, fascia, ligaments, tendons etc). "A joint doesn’t have to just influence a joint and a muscle influence a muscle. All these structures work and interact together. A great example of this is the upper body cross syndrome." 
- Butler and Major suggested that there should be a clear distinction made between joints with active neuromuscular control (e.g. sitting up straight without back support and the thighs and feet supported) versus those with control deficiencies (e.g. sitting with a collapse of the lumbar spine). The authors proposed new terminology: Controlled Closed Kinetic Chain (CCKC) and Controlled Open Kinetic Chain (COKC). CCKC = system of links forming a closed loop, continuously or for a moment where “a maximum of three of the articulations between links needs to be under active control”. COKC = continuous active control of all the articulations where one part of the chain “may be in contact with a support surface” (but is not a requirement). 
Open and Closed Kinetic Chain Exercises in Rehabilitation
- Open Kinetic Chain Exercises
- Closed Kinetic Chain Exercises
- ACL Rehabilitation
- Patellofemoral Pain Syndrome
- Hamstring origin tendinopathy
- Internal Impingement of the Shoulder
- Lateral Collateral Ligament Injury of the Knee
- Sinding Larsen Johansson Syndrome
- Bankart lesion
Open vs. Closed Chain Exercises
The common belief is that Closed Chain exercises are the preferred rehabilitation for anterior cruciate ligament (ACL) injury because of increased strain, joint laxity, and anterior tibial translation that can occur during Open Chain exercises. Glass et al did a systematic review of 6 randomized controlled trials about the effects of Open Chain and Closed Chain exercises on ACL deficient or reconstructed knees. 
The results of the review was that both open and closed kinetic chain exercises could be used for the rehabilitation of ACL deficiency and post ACL reconstruction. Both types of exercises had similar outcomes on knee pain, laxity, and function. One study suggested starting the rehabilitation with Open Chain exercises and then progress to Open Chain function. The reviewers found that an approach utilizing both open and closed chain exercises should be warranted in ACL rehabilitation, especially in sports where complex movement patterns exist that includes both Open Chain and Closed Chain actions. 
This confirms another systematic review performed on 12 studies that found “no differences between Open Chain and Closed Chain exercises in their effect on accelerated rehabilitation after ACL reconstruction”. They also found that a combination of Open Chain and Closed Chain exercises could be more effective to accelerate rehabilitation. 
Mikkelsen et al concluded that a combination of both Open Chain and Closed Chain quadriceps exercises is better than only Closed Chain quadriceps exercises after ACL reconstruction. These authors found that the combination of exercises led to “significantly better quadriceps muscle torque and significantly earlier return to original sports at the same level as prior injury without compromising knee joint stability”. 
Shoulder Rehabilitation 
Historically, shoulder rehabilitation was mostly done utilizing Open Chain exercises. The reason was the ease of administering the exercises and the idea that most athletic activities are naturally open kinetic chain movements.
With different studies, Closed Chain exercises were found to be more beneficial in shoulder rehabilitation than Open Chain for the following reasons:
- They emphasized co-contraction force couples around the scapula and shoulder
- They allowed the rotator cuff to work as a “compressor cuff”
- They required grading, coordination and sequential muscle activation, co-contraction and proprioceptive feedback.
Early in shoulder rehabilitation, Open Chain exercises are less desirable because they create greater shear forces and require a larger range of motion. The combination of scapular stabilization exercises and Closed Chain exercises provides a stable scapular base and early rotator cuff strength necessary to advance to the open chain exercises”. Rehabilitation of the shoulder requires a thorough assessment of the entire kinetic chain.
Recent Related Research (from Pubmed)
- ↑ Karandikar N, Vargas OO. Kinetic chains: a review of the concept and its clinical applications. PM and R. 2011 Aug 31;3(8):739-45.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 Ellenbecker TS, Davies GJ. Closed kinetic chain exercise: a comprehensive guide to multiple joint exercise. Human Kinetics; 2001. Available From: http://bit.ly/1NunaL7
- ↑ 3.0 3.1 3.2 Rivera JE. Open versus closed kinetic chain rehabilitation of the lower extremity: a functional and biomechanical analysis. JSR. 2010 Apr 21;3(2).
- ↑ Reinold M. The Problem with the Kinetic Chain Concept blog [Internet]. Mike Reinold – [cited 13 May 2016]. Available from: http://www.mikereinold.com/the-problem-with-the-kinetic-chain-concept/
- ↑ Butler PB, Major RE. The Missing Link?: Therapy issues of open and closed chains. Physiotherapy. 2003 Aug 31;89(8):465-70. Available from: (https://www.researchgate.net/publication/256824027_The_Missing_Link)
- ↑ 6.0 6.1 Glass R, Waddell J, Hoogenboom B. The effects of open versus closed kinetic chain exercises on patients with ACL deficient or reconstructed knees: a systematic review. North American journal of sports physical therapy: NAJSPT. 2010 Jun;5(2):74. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2953392/
- ↑ Azab M. The effectiveness of open versus closed kinetic chain exercises In accelerated rehabilitation after anterior cruciate ligament Reconstructive surgery: A Systemic Review. Available from: http://sttereizaptandrehab.com/Project_final_submission.pdf
- ↑ Mikkelsen C, Werner S, Eriksson E. Closed kinetic chain alone compared to combined open and closed kinetic chain exercises for quadriceps strengthening after anterior cruciate ligament reconstruction with respect to return to sports: a prospective matched follow-up study. Knee Surgery, Sports Traumatology, Arthroscopy. 2000 Nov 1;8(6):337-42. Available from: http://www.udel.edu/PT/PT%20Clinical%20Services/journalclub/sojc/08-09/Nov08/Mikkleson.pdf
- ↑ Hyde TE, Gengenbach MS. Conservative management of sports injuries. Jones &amp;amp;amp;amp; Bartlett Learning; 2007. Available from: http://bit.ly/1OreHbG
- ↑ Aspire Health and Wellness. Closed vs Open Kinematic Chain Available from: https://www.youtube.com/watch?v=TV2CyvmMhRE
- ↑ Institute Education. Open and Closed Chain Exercises Available from: https://youtu.be/_RZCz0e6I38