Same six reps. Four different sessions.

The problem

The rep count tells you almost nothing about what the set actually did.

Two lifters do a dumbbell row. Same weight, same ten reps. One takes forty-five seconds over it. The other rips through in eight and drops the bells on the floor. I have watched that comparison play out for thirty-five years and it never stops being the same lesson.

Everything else on the sheet gets argued about. Exercise selection, sets, rest, percentages. Then a parameter that changes the demands of the set gets left blank, and the lifter fills it in with whatever rhythm he happens to prefer.

This piece is about filling it in on purpose. By the end you should be able to take one exercise and one rep bracket and aim it at four different training goals, and know when doing so will help an athlete and when it may work against the goal. It is written mainly for young coaches, and for the lifter who leaves the gym unsure what the session was for.

The tool

The four numbers

• First digit: the eccentric. Lowering. The muscle lengthening under load.
• Second digit: the pause in the stretched position. Bar on the chest. Bottom of the squat. Poor leverage.
• Third digit: the concentric. Lifting. An X means accelerate as hard as you can.
• Fourth digit: the pause in the shortened position. Locked out. Top of the curl. Good leverage.

A bench press at 4210 is four seconds down, two paused on the chest, one second up, straight into the next rep.

Two traps catch nearly everyone in the first month.

The digits are ordered by contraction type, not by what happens first in the exercise. On a lat pulldown the concentric comes first, but it is still the third digit. A pulldown written 3010 means one second to pull and three to return. Write it in movement order and you will get it backwards, and so will everyone you coach.

And X does not mean the bar moves fast. It means you are trying to make it move fast.

Under a heavy load the bar will crawl, and that is fine: the nervous system responds to the attempt, not to the stopwatch. This is well established and it is the single most useful item on the list, because it means you can train explosive intent with heavy weight.

Why the same reps stop meaning the same thing

Once you have a tempo, you have a clock.

Time under tension is one way I change the demands of a set. Alongside load, effort and rest, it influences fatigue, the contribution of different energy systems and the training stimulus. The time ranges below are my coaching guidelines, not fixed points where one energy system switches off and another takes over.

Time under tension: practical programming ranges

These are coaching windows, not switches between energy systems. ATP–PCr, glycolytic and oxidative pathways contribute together. Their relative contributions depend on more than duration alone, including load, effort and how the set is performed.

My working durations are starting points, not guaranteed outcomes. I adjust repetition range, loading, rest and tempo around what the athlete is developing and what I see in training and in the game.

Now take six reps and change nothing but the tempo.

Six reps at four tempos, with resulting time under tension

Where X is used, the timing is an estimate. X means the intent to accelerate, not a fixed one-second concentric.

Eighteen seconds to sixty. Same exercise, same six reps, same sheet. Four sessions.

Six is arbitrary here: I picked it because it holds the arithmetic still. Run the same exercise at four reps or at ten and the whole table moves. What matters is the relationship, not these four rows.

The two pause positions do opposite jobs. Pausing in the stretched position raises tension by dissipating the elastic energy you would otherwise get for free: the muscle has to work harder for the same weight. Pausing in the shortened position does the reverse: a rest in the strong position lets you handle more load and biases recruitment toward high-threshold motor units. So 44X1 for size. 40X3 for force. Same bench press, opposite intent.

The whole thing on one page

The tempo map

Reps and tempo together help establish how long a set lasts. That changes its demands, but does not determine a single energy system or guarantee a particular adaptation. Here is how I use different combinations to give the work a different emphasis.

Tempo, repetitions, approximate time under tension and programming emphasis

These are examples of programming emphasis, not guaranteed training outcomes. X-tempo durations are estimates because concentric speed is not fixed.

Read it downwards and you can see how the work changes. As repetitions and time under tension increase, I will often reduce the load to maintain the prescribed tempo and technical standard. But longer sets do not automatically mean greater muscle growth or less transfer to sport. Nothing in that table is better than anything else. They are five different purchases.

Treat these numbers as starting points rather than a rulebook. The tempos are the ones I often reach for, not the only options. Adjust the combinations to fit the athlete, the training objective and the full prescription.

Two limits on the map, both worth knowing before you lean on it.

It does not show rest. Two sets with identical time under tension and different rest intervals are not the same training session: the same forty seconds with three minutes' rest and with forty-five seconds' rest produce genuinely different hormonal and metabolic outcomes. Tempo and rest interact, and you can use one to compensate for the other. That is an article of its own and I will write it.

And there is not a single percentage of 1RM in it, deliberately. There is no reliable way to attach a percentage to a tempo-prescribed set. What eighty percent means for six reps depends on the muscle, the exercise, the athlete's fiber makeup and his training age, and it moves as he gets stronger. Sometimes the load matters more than the tempo, and sometimes what actually needs measuring is an output — bar speed, jump height, how he moves the next morning — rather than either one. That is a third article, and honestly it may be the more important one.

What it costs

What a slow concentric actually costs you

This is the part almost nobody thinks through, and it decides where tempo work belongs in a year.

Eccentric work can be surprisingly economical during the effort. When a muscle produces force while lengthening, it generally requires less energy than producing comparable force while shortening. But a lower energy cost in the moment does not tell me how the player will feel tomorrow.

An unfamiliar or demanding dose of eccentric work can bring soreness and temporarily reduce force output. A player who has built tolerance to it may respond very differently.

The load, volume, range of motion, previous exposure and where we are in the season all matter. So I don’t treat a four-second lowering as a guaranteed growth stimulus or a guaranteed recovery problem. It is a way to shape the demands of a repetition, and I have to program the rest of the week around the player’s response.

A fast concentric is about intent. I want the athlete to accelerate, even when the load means the bar itself moves slowly. That intent can be valuable for strength and power development. But fast does not automatically mean low fatigue or untouched glycogen stores. The full prescription matters.

A deliberately slow concentric changes the demand. It gives the athlete more time to control the movement and may require a lighter load to complete the prescribed repetitions. It can also create considerable fatigue. But tempo alone does not tell me how much glycogen was used, how much force was produced or what the athlete will recover from by tomorrow.

That is why I look beyond the rep. Load, effort, volume, rest and the player’s training and game schedule all matter. I am not choosing between nervous-system fatigue and glycogen depletion as though they were two separate bills.

Tempo is not only a set-level decision. It is a calendar decision.

The expensive mistake

The muscle has a job.

Here is the mistake I see most often in young coaches. They pick a tempo for the goal and forget to check it against the muscle.

Muscles are not interchangeable. They have different roles, and their fibre-type composition can differ considerably. The soleus, for example, generally contains a high proportion of slow-twitch fibres. But population averages do not tell me the exact fibre makeup of the athlete standing in front of me.

My programming choices follow the qualities the athlete needs.

For soleus-focused work, I often use longer sets, sometimes 15–25 repetitions, when developing local muscular endurance and loading tolerance. For hamstrings and other muscles involved in rapid force production, I often include shorter sets with explosive intent, alongside progressive eccentric work.

Those are programming choices, not fixed physiological rules. A short set can still stimulate the soleus, just as a slower hamstring exercise can have a useful place in a program. What matters is the quality I want to develop, the exercise I choose and how the athlete responds.

Ask what the muscle does, then what the block needs, then what tempo. Not the other way round.

Developing strength in an exercise is not the same as improving speed in sport. A slow hamstring curl can develop strength and control. But I would not expect that exercise, performed with a deliberately slow concentric, to produce an immediate improvement in sprint speed.

And here is where I take a stronger position. If deliberately slow concentric work becomes the only training emphasis over an extended period, particularly for muscles that must produce force rapidly in sport, I expect speed development to suffer. The athlete may become stronger in the gym while his ability to express that strength quickly stagnates or even declines.

That does not mean slow training automatically makes someone slower. It means we cannot neglect the qualities we expect the athlete to demonstrate at speed. Strength must be developed, but so must the ability to express force rapidly. This is why I keep high-velocity work and explosive intent in the program, even during periods when slower strength work takes priority. Research has compared slower and faster approaches to hamstring training with differences in sprint outcomes, but comparisons also involve other training variables; they do not prove that one four-second concentric makes an athlete slower. This remains a coaching judgment to test against actual sport performance.

I am not interested only in how much stronger the athlete becomes. I want to know whether that strength makes him better at his sport.

Check this before you write four digits

And the exercise has a shape.

The second thing to check is the exercise itself, specifically its strength curve, meaning how the resistance lines up against your leverage through the range.

Slow tempo work only makes sense where the exercise can carry it. If the load falls away at one end of the movement, a long eccentric spends part of its time in a zone where almost nothing is happening, so a longer rep does not necessarily mean more tension throughout the movement. If there is a pronounced sticking point, the weight you can use is capped by that one angle, so the rest of the range is under-loaded no matter how carefully you count. Either pick an exercise whose resistance profile matches the muscle, accommodate it with chains or bands, or put the pause exactly at the angle that is limiting you and stop pretending the rest of the range is being trained.

Range of motion matters too, but a longer movement does not automatically need a slower eccentric. A technically demanding exercise may require more deliberate control, but the tempo must still serve the purpose of the lift.

A squat and a wrist curl place very different demands on the athlete. I cannot simply apply the same tempo prescription to both and expect it to mean the same thing.

Shorter-range exercises, such as calf raises, bring their own considerations. I can use pauses, controlled eccentrics and different repetition ranges, but I still need to consider loading, execution and what I want the muscle to develop.

The point is not to make every exercise slower. It is to choose a tempo the exercise can carry and the athlete can execute for the intended purpose.

Then there is the category where most of this stops applying entirely.

Never put a slow eccentric or a slow concentric on a classic lift.

A snatch, a clean, a jerk, a power version of any of them — those are X on both. The concentric is the exercise: the whole point is maximum rate of force development, and a one-second pull is a failed lift, not a slow one. And there is no eccentric worth prescribing, because you are catching kilos or returning them, not lowering them under control. Writing 3010 next to a power clean tells me you have not understood what the movement is for. A useful weightlifting tempo looks like XOXO, and mostly you leave it alone.

What you can play with is the other two digits. The pauses are where the coaching lives in these lifts, and they are genuinely powerful:

• A pause above the knee on a clean pull, for the athlete who rushes the first pull and arrives at the hip with nothing left to give.
• A pause in the receiving position, to build the confidence and the positional strength to stay under the bar.
• A pause at whichever point in the pull the athlete keeps skipping past.

Note that this is the second digit doing a job it is not usually described as doing: a pause part-way through the concentric, at a chosen joint angle, rather than in the stretched position at the bottom. Same digit, and one of the more useful things you can do with it.

And if you want slow work inside a weightlifting program, you use the derivatives, not the competition lift. A snatch deadlift from a podium on a five-second eccentric is excellent. A slow snatch is not a thing.

Three mistakes

Where this goes wrong in practice.

Counting instead of lifting. If attention is on the clock rather than the load, tempo has cost more than it bought. Teach it in the warm-up sets, then let rhythm carry the working sets. A tempo you have to think about is a tempo you have not learned yet.

Using tempo instead of load. Slowing everything down feels productive and produces a hard session with no progression underneath it. Tempo changes the direction of the stimulus. It does not replace adding weight over time.

Leaving the column blank. I write a tempo on every program, and this is why. Left to himself, every lifter drifts back to the rhythm he is already good at. Nothing wrong with that rhythm. It is usually why he has whatever he has. But the qualities he lacks are almost always sitting at the tempos he never uses. The prescription exists to make the unfamiliar happen on purpose. Where I give ground is on the day: when the session is about expressing strength rather than building a quality, I get more forgiving about the last two reps.

Take it to the gym

Pick one lift this week. Write four digits next to it. Count them out loud on the first set.

• The rep range, tempo and load work together. When a bracket is prescribed for technical failure, choose the load that brings the athlete to failure within the bracket at the specified tempo and technique. Too few reps: reduce the next set. Extra reps still possible at the top: increase the next set. Some sessions deliberately use an earlier stop.
• Protect the intended quality. End a technical-failure set when the prescribed standard can no longer be maintained. In explosive or low-fatigue work, stop earlier when that better serves the goal.
• Shorter sets: Can emphasise explosive intent and strength, depending on the load, rest and effort.
• Intermediate set durations: Useful in several strength and hypertrophy approaches; not a unique energy-system window.
• Longer sets: One way to accumulate work, not a guarantee of greater muscle growth.
• Down slow, up fast is the default. Three to five seconds on the eccentric; slower than that and you reach the concentric already tired.
• X is intent, not speed. Try to throw it. The bar will do what it does.
• Concentric speed changes the demands of the set. Use explosive intent or deliberate control according to the goal, but judge fatigue cost from the full prescription, not tempo alone.
• Stretched pause raises tension for the same load. Shortened pause lets you use more load.
• Ask what the muscle does before choosing the tempo. Match exercise, athlete and programming objective; fibre-type averages do not dictate universal rep ranges.
• Check the strength curve before you slow anything down. No point counting seconds through a range where the load has fallen off.
• Classic lifts are X on both. Coach them through the pauses, and put your slow work in the derivatives.
• Match tempo to the exercise. A longer range does not automatically demand a longer eccentric.
• Ride a wave, do not run blocks. Change what leads, keep everything else on the sheet in a small dose. A quality that took eight weeks to buy can often be held with one set.
• Let the emphasis change across the year. Often that means moving towards faster intent as competition approaches, while keeping the slower work a player still needs. Testing, response and the competitive schedule guide the progression.
• No percentage survives a tempo change. Eighty percent for six reps means nothing until somebody says at what speed.

The first lifter finished his ten reps in eight seconds. Give him the same ten at 4210 and he will find out, somewhere around rep four, exactly what he has been avoiding.