7.2 Tempo, Time Under Tension, and Contraction Phases

Tempo is how you spend the seconds inside a set

DCO 2.A.6 is not asking whether the client “trained hard.” It is asking whether you can assign a tempo that matches the contraction phases you care about. Two clients can both perform 10 squats at 150 lb. One drops into the hole and rebounds. The other lowers for three seconds, pauses a second, and stands in one second. Those are different training stresses: different time under tension (TUT), different muscle actions, and different skill demands.

Tempo is the planned duration of each phase of a repetition. Time under tension is the total loaded time in a set — approximately (seconds per repetition cycle) × (repetitions). TUT is a consequence of tempo, reps, and any pauses. It is a useful coaching number. It is not an NSCA-published single “optimal seconds” policy. Items that claim every hypertrophy set must last exactly 40 seconds, or that NSCA-CPT scoring uses a secret TUT cutoff, are inventing a rule the outline does not publish.

Contraction phases you must be able to name

Every repetition is some combination of three muscle actions:

• Eccentric — the muscle lengthens under load (lowering the bar, sitting into a squat, the down phase of a pull-up).
• Isometric — the muscle produces force without changing length (a pause in the hole, a plank, a long pause at a sticking point).
• Concentric — the muscle shortens under load (standing up, pressing the bar, the up phase of a row).

Power and plyometric drills add a stretch-shortening cycle: a fast eccentric, a brief amortization (isometric-like coupling), and an explosive concentric. If you deliberately lengthen amortization with a long pause, you are no longer training that reactive cycle; you are training a paused strength lift. That can be useful for teaching. It is the wrong tempo if the goal is elastic power.

Notation: read 3-1-1-0 from left to right as lowering first

The most common four-number string on this exam is:

eccentric – isometric pause – concentric – pause between reps

Example: 3-1-1-0

• 3 = 3-second eccentric (lowering).
• 1 = 1-second isometric at the end of the lowering phase (pause in the hole or on the chest).
• 1 = 1-second concentric (standing or pressing).
• 0 = no extra pause at the top before the next repetition.

Some coaches write three numbers (ecc–pause–con) and skip the last digit. Some write X for an explosive concentric (for example 3-0-X-0). If a stem gives four numbers without defining them, default to lowering first, not “concentric first.” Assigning 3-1-1-0 and then coaching a 3-second lift with a 1-second drop is the opposite prescription.

Worked TUT math (illustration, not a policy target)

Ten repetitions at 3-1-1-0 spend 3 + 1 + 1 + 0 = 5 seconds per repetition. Set TUT ≈ 5 × 10 = 50 seconds.

Five repetitions at 1-0-X-0 might spend about 1–2 seconds each if the concentric is truly fast. Set TUT might be 5–10 seconds. That short TUT is expected in power work. It is not a failed hypertrophy set; it is a different goal.

Twelve repetitions at 1-0-1-0 (about 2 seconds each) yield about 24 seconds of TUT — muscular-endurance density if rest is also short. Same 12 reps at 3-1-1-0 would yield about 60 seconds of TUT. Reps alone do not define TUT; tempo does.

Do not memorize 40, 50, or 70 seconds as “the NSCA hypertrophy law.” Research papers discuss TUT ranges; the CPT outline asks you to manipulate phases, not to hit a secret second-count.

When to slow the eccentric

A slow eccentric (often 3–4 seconds) is a programming choice, not a moral virtue. Use it when you want one or more of these outcomes:

• Skill: the client can feel foot pressure, brace, and joint path on the way down. Novice squats, RDLs, and push-ups often need this before load climbs.
• Tissue loading through lengthening: tendons and muscle experience high force while lengthening; a controlled lower is a common hypertrophy and “own the range” strategy.
• Longer TUT without adding reps: 8 reps at 3-1-1-0 already last about 40 seconds; 8 reps bounced in one second each do not.
• Safety on the descent: a client who crash-lands into knee valgus needs a slower lower more than a faster up.

Slow eccentrics are a poor default when:

• The lift is ballistic (jump squat, kettlebell swing, Olympic-style clean or snatch). You cannot “3-second eccentric” a jump and still train the stretch-shortening cycle you came for.
• Fatigue from an extra-slow lower destroys the concentric you needed for power or for a heavy strength set.
• Pain appears during the lengthening phase — then you regress range or load rather than slower-er the same painful path.

When to punch the concentric (power)

Power is force × velocity. On the exam, that means an explosive concentric once the client can start from a safe position. Coaching cues sound like “stand up fast,” “push the floor away,” or “throw the ball to the wall,” not “lift in four seconds.”

Pair that concentric with:

• Loads from the power table in 7.1: about 75–90% 1RM for strength-speed, about 30–60% 1RM for speed-strength.
• 1–5 reps so velocity does not die on rep 8.
• 2–5 minutes of rest so the next set is still fast.
• An eccentric that is controlled enough to be safe, not theatrical. A jump squat’s eccentric is brief by nature; a paused box squat used as a strength teacher is a different exercise.

If you assign 3-1-1-0 to a hang clean, you have rewritten a power lift into a slow pull. That may be a teaching regression for the pull pattern. It is not power development.

Isometrics without turning every set into a plank

Isometric seconds in the tempo string are pauses, not a full isometric session.

• A 1-second pause in the squat hole teaches depth and kills the bounce.
• A 2-second pause on the chest in a bench press can expose a weak press-off without changing the load yet.
• Long isometrics (wall sits, long planks) are their own type of work. They can support stability goals. They do not replace the concentric intent of a strength or power set.

Match the pause to the goal. Hypertrophy and teaching tolerate pauses that lengthen TUT. Power usually wants a short amortization, not a two-second dead stop, unless you are specifically training a paused strength position.

Worked scenarios

Hypertrophy-oriented bench. Goal is muscle size, not a 1RM. Prescribe 8–10 reps at a load near an 8–12RM, rest about 60 seconds, tempo 3-1-1-0. TUT is about 40–50 seconds. The slow lower and brief chest pause keep the client from bouncing and keep tension on the pecs and triceps.

Novice squat pattern. Before adding load, use a goblet squat at 3-1-1-0 or 3-2-1-0 so the client owns depth. Here tempo is a teaching tool. TUT is a side effect.

Speed-strength jump squat. Load about 30–60% of squat 1RM, 3 reps, rest 2–3 minutes, tempo 1-0-X-0. Cue a stiff, fast turnaround. Do not add a 3-second eccentric.

Client with a physician note: no ballistic loading for 8 weeks after an Achilles repair (cleared only for slow resistance). You may still train the posterior chain, but you honor the restriction: slow, controlled concentrics and eccentrics, no jump tempo, no “X” concentric on hops. Tempo is how you stay inside the medical limit without pretending the goal is still sport power.

Exam traps

• First number is eccentric seconds, not sets and not rest minutes.
• 3-1-1-0 × 10 reps ≈ 50 s TUT, not 3 seconds total and not a required NSCA optimum.
• Explosive concentrics belong with power loads and long rest, not with 20-second rests and 15-rep sets.
• Slow eccentrics belong with control and many hypertrophy prescriptions, not with proficient Olympic-style or jump training.
• There is no single unpublished TUT second-count that the NSCA-CPT uses as policy for every client.