Closed kinetic chain exercise (CKC)

A closed kinetic chain exercise (CKC) keeps the distal segment, such as the hand or foot, stationary against resistance that restrains its movement.^{1Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 631.} Squats and push-ups are the NSCA’s examples.^{1Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 631.} The IPTA describes closed-chain motion as the proximal part of a bone moving about a fixed distal segment.^{2International Personal Trainer Academy, Certified Personal Trainer Textbook, p. 93.}

Movement at one joint makes the other joints move in a predictable way.^{3Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 71.} In a squat, knee flexion requires hip flexion and ankle dorsiflexion, and the joint torques are coupled.^{3Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 71.}

In practice

• Lower-body closed-chain exercises are often described as more functional because most sport activity occurs with the feet fixed to the ground; advantages include greater joint stability and coordinated joint movements that resemble sport.^{1Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 631.}
• The NSCA’s program design guide describes closed-chain exercises as safer after knee ligament injury because force acts more perpendicular to the tibia’s joint surface, reducing ligament strain.^{4Hoffman, NSCA’s Guide to Program Design, p. 221.}
• Limited range of motion or weakness at one joint can limit the whole exercise.^{3Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 71.}
• Most activities involve both closed-chain and open-chain exercise; sprinting combines them within one stride.^{1Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 631.}

Why definitions vary

The NSCA’s strength and conditioning text defines the category by considerable resistance at the terminal joint.^{1Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 631.} Its personal training text notes that squats and leg presses are kinematically similar despite different foot movement, and that bench presses and push-ups produce similar muscle activation even when resistance is hardly “considerable.”^{3Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 71.} It reports no exact consensus on the definitions.^{3Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 71.}