Repetition
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One complete movement of an exercise, from the start position through the full motion and back, made up of a concentric, mid-range, and eccentric phase.
Detail
A repetition is a single completed movement of an exercise, carried out from the starting position through the entire movement and then back to the starting position (Fleck & Kraemer, 1997). Each repetition has three phases:
- Concentric phase — the muscle shortens against a load. The lifter should refrain from using momentum (which reduces muscular loading), move in a deliberate and controlled manner, and avoid ballistic-type movements, which compromise safety and effectiveness.
- Mid-range position — the position of full muscle contraction. A brief pause here eliminates the effects of momentum.
- Eccentric phase — the lowering phase of the movement (the muscle lengthens against the load). This phase needs to be emphasized for optimal muscular hypertrophy. The eccentric phase is about 40% stronger than the concentric phase, so it should be accentuated.
A useful mnemonic (R-E-P-S):
- R: Refrain from using momentum during the concentric phase.
- E: Emphasize the mid-range position.
- P: Perform the eccentric phase in a deliberate fashion.
- S: Stimulate your muscles throughout the range of motion.
Key facts
- A repetition = one full movement out and back to the start.
- Three phases: concentric (shortening), mid-range (full contraction), eccentric (lengthening/lowering).
- Eccentric phase is ~40% stronger than the concentric phase.
- Emphasize the eccentric phase for hypertrophy; avoid momentum and ballistic movements.
Connections
- Repetition Maximum (RM) — reps are counted toward a repetition maximum (RM).
- Tempo / Time Per Repetition — time spent in each phase per repetition.
- "Muscle Action" vs. "Contraction" — The Terminology Argument — concentric/eccentric/isometric muscle actions.
Sources
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Educational content only — not medical advice. Always consult a qualified professional for individualized guidance, especially around injury, pregnancy, or medical conditions.