An exercise physiologist measures peak force production by the same muscle group under three conditions: lifting a submaximal load concentrically, holding a load isometrically, and lowering a supramaximal load eccentrically. Rank the expected peak forces:

• A Concentric greater than isometric greater than eccentric
• B Isometric greater than eccentric greater than concentric
• C Eccentric greater than isometric greater than concentric ✓
• D All three produce identical peak force at the same muscle length

Explanation

Eccentric contractions generate the greatest force because the cross-bridges resist being forcibly stretched while the passive elastic elements of titin and connective tissue add their recoil, and fewer bridges need to detach actively since external work assists. Isometric contraction comes next, with full cross-bridge attachment but no elastic contribution from stretch. Concentric shortening produces the least force because bridge formation and detachment consume part of the available force. This ordering follows directly from the force-velocity relationship extended into the lengthening region.

Reference: Ganong's Review of Medical Physiology, 26th ed.

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