Tempo binnen krachttraining: TUT, concentrische & excentrische fase

De gemiddelde fitnessbeoefenaar volgt geen vast trainingsschema. Degenen die wél een trainingsschema gebruiken, spitsen zich meestal toe op het gewicht, het aantal reeksen (sets) en de herhalingen (reps).

Dit leidt nog steeds tot een vrij brede interpretatie van de workout met geen specificering van onder andere de snelheid van de uitvoering of de rust tussen tussen sets. Er zijn manieren om de trainingsprikkel te intensiveren om op die manier meer spiergroei en sneller resultaat te realiseren. Niet door enkel te focussen op het aantal sets of herhalingen, maar juist op de intensiteit van de oefening en de snelheid van uitvoering. Maak kennis met het begrip ’time under tension’ (TUT).

Het vervolg van deze blog wordt uitgeschreven in het Engels om het doelpubliek niet te beperken.

Think you know all there is to know about program design?

Everyone’s familiar with the basic components of a strength-training program, like sets, reps, rest periods, exercise selection, how many days per week you train, etc.

But show me a coach that truly understands – and properly applies – time under tension to their programs, and I’ll show you a coach who’s getting great results with their clients and athletes.

Time under tension

Tempo is one of most important loading parameters as it has a major impact on the training effect. Tempo as a concept has been around since the inception of bodybuilding. Many successful bodybuilders vary their tempo throughout the training cycle.

Tempo is the program design variable referencing the speed of movement for an exercise. A different consideration of tempo is the time under tension (TUT), which is the length of time that muscle fibers are under mechanical tension from a resistance-training exercise.

Along with intensity, TUT is critical for creating the desired stimulus for increasing muscle definition or size. For maximizing strength, the ideal TUT is about 20 seconds or less; for muscle mass, it’s around 40-60 seconds and for muscle endurance, it’s at least 70 seconds.

Mechanical strain on muscle fibers signal the mechanisms responsible for repairing structural damage to existing fibers and laying down the foundation for new muscle cells.

Tempo training

Ian King, an Australian strength coach, did not invent tempo, but he popularized the system of writing tempo. Charles Poliquin, a Canadian strength coach, is also credited with bringing this concept to mainstream. Tempo simply refers to the rate at which you move the weights. If you are not paying attention to tempo when you train, you may be missing out!
Tempo consists of 4 numbers:


The first number is for the negative or eccentric phase – in other words, when you are lowering the weight and the eccentric contraction occurs and the muscle lengthens under load. For a squat and a bench press, this would mean lowering the weight. For a cable row, this would mean returning the plates to the stack. The eccentric contraction is the most important in building size and strength.


The second number is the pause after the first phase is complete and the muscle is lengthened, between the eccentric (lowering) phase and the concentric (lifting) phase of a repetition. For example, in the bench press, this is a pause as the weight is held stationary just above the chest. Pauses in the disadvantageous position of a lift, such as the bottom position of a squat, increase intramuscular tension and decrease the stretch reflex.


The third number refers to the concentric contraction or positive phase. The concentric contraction occurs when a muscle shortens, such as when you stand up from the bottom of the squat. For a bench press, this would be driving the bar upwards. If an „X“ is used in the formula, it implies an explosive contraction with full acceleration. In this case the intent is more important than the actual visual lifting speed of the bar


The fourth number is usually left out, but if present, refers to the pause when the muscle is shortened. This is the point that occurs at the end of the concentric phase, such as when you have extended your elbows fully at the top of the hanging dip. Pauses in this “advantageous” position also increase the recruitment of fast-twitch fibers. Those fast-twitch fibers are the fibers that are crucial in developing power, strength and size.

Why use tempo training?

The body will adapt to any training regimen in time, so tempo prescriptions should be varied just like any other training variable. Repetition speed is important because different lifting speeds produce different training effects.

Now let’s explore what tempo can do for us.

Short version:

  • Improved body awareness.
  • Improved control of lifts.
  • Development of connective tissue strength.
  • Improved stability.
  • Focus on muscular elements versus tendinous elements (a slow, controlled motion is going to place more stress on the muscles, whereas a bouncy or ballistic motion will place more stress on the tendons, etc.).
  • Develop work capacity

Long version:

Tempo affects many variables of training. The first, and possibly the most significant, is time under tension. Tension is what forces the muscle to contract and perform work. It is tension that fatigues the muscle and tension that triggers the response to training – a combination of strength (neural) adaptation, and/or mass (hypertrophy). So tension is a key factor to manipulate, and one of the ways to manipulate time under tension is tempo.

  • Improve mechanics

The priorities always remain technique, consistency and intensity. Tempo prescriptions can reinforce this, especially in beginner athletes. You can slow the movement down, allowing the athlete to stay in the proper position by developing awareness and body control. Once consistency is demonstrated, speed and intensity can be added to the equation.

For advanced athletes, tempos can be useful in correcting poor movement patterns and strengthening weak positions or lifts altogether. If you struggle to maintain good posture at the bottom of your lift, a pause would force you to become more comfortable and stronger in that position, allowing you to improve your technique and likely increase your lift in the process. A prescription forcing you to spend some time in that position will strengthen you in that specific range of motion and help get past the “sticking point.”

  • Prevent injury

You can also increase time under tension  and recruit more muscle fibers with tempo prescriptions, while keeping the stress on the body and nervous system relatively low.

Improving movement quality and technique will help reduce the risk of training related injuries. But slowing down lifts with tempo prescriptions might also help take undue stress off the joints and shifting it to the muscles, which are far more capable of adapting to increased loads and stress.

Slow tempos and pauses can also help prevent injury by naturally regulating intensity and egos. Sometimes, athletes will overload a lift, resorting to bad form and bad habits to “get the work done.” With a pause, you can’t bounce a bench press off your chest. It’s also hard to perform a deadlift with a rounded back when using a 3-count. By using tempos, it becomes much more difficult to mask poor movement with speed.

  • Get stronger

If the first two reasons didn’t convince you, hopefully this does.

Tempo training makes you stronger…faster. It not only adds variety to your training, but also puts a different stimulus on your body and nervous system, allowing greater adaptation, increased strength and less plateaus.

Speed allows you to harness the power of your muscles’ elasticity by utilizing the stretch-shortening cycle (SSC) of your muscle fibers and other soft tissues. By slowing movements down and adding a pause between the eccentric (lowering) and concentric (ascending) phases of a lift, you eliminate this the SSC, allowing the muscle(s) to become stronger without it’s help.

  • Maximum force

Trying to accelerate the weight as much as possible is the best way to maximize force production (F=m x a). And when trying to build explosiveness it is likely the best way to do your reps on the big compound lifts once you have achieved a high level of technical mastery.  But that type of contraction comes with its limitations and doesn’t mean that you are producing maximum force over the full range of motion.

When you try to be violently explosive with the weight you are creating a burst of acceleration and speed at first. This creates momentum. And momentum decreases the need to produce maximum (it’s easier to keep a load moving on its own momentum than to get it moving when it is not accelerating). The more momentum (through high acceleration) you can produce at the beginning of the movement the more likely you are to reduce force production and muscle contraction over the rest of the range of motion.

So, by doing maximum acceleration reps you are indeed improving your capacity to create a lot of force, but you might not maximally strengthen the full range of motion.

  • Hypertrophy

Training for hypertrophy (muscle volume) and strength endurance requires keeping a muscle under tension for an extended period of time to create the metabolic stimulus necessary for growth.

Faster reps allow you to use heavier weights, but reduce tension, so you’re trading size for power and speed. Maximum strength training with heavier loads (85-100% 1-RM) generally requires a faster, more explosive tempo to create a mechanical stimulus and recruit all available muscle motor units. Even though the weight might not be traveling that fast, the lifter is pushing as hard as possible to generate momentum, which is defined as the product of a mass and its velocity.

In the world of running and endurance, tempo training can be very useful in developing speed, cardiorespiratory endurance and stamina. Though implemented quite differently in strength training, tempo protocols can be just as valuable in developing strength, power, and speed.

Concentric phase


Even if your goal is maximum strength and performance, there is value in using concentric actions where you do not try to create acceleration. For example, pressing the weight in 2 or 3 seconds in the bench press will make you have to use intense muscle contraction at every point in the range of motion, leading to a more complete strength gain. At first you might not be able to use as much weight, but the muscles are working harder and getting more stimulation because maximum tension is produced over a fuller range of motion.

Another benefit of a more controlled, slower concentric movement is that it allows you to better focus on contracting/flexing the target muscle as hard as possible. This increases muscle recruitment and over time develops better mind-muscle connection, which is an essential skill when it comes to maximizing growth.

Concentric-only training

Concentric-only training like the Prowler sled push, which is usually used in strongman training, offers less muscle damage. This is pratical when you have to train the next day and can’t afford muscle soreness.

Eccentric phase


When you lift a weight concentrically, you produce greater metabolic stress. However, research has also shown that when you lengthen the muscle eccentrically, you can increase protein synthesis more than with a concentric contraction.

This happens through the activation of satellite cells in the eccentric phase. The result of this activation is increased muscle fiber size and the addition of the satellite cell’s nucleus to the muscle. The latter step is critical, because the nuclei in the muscle are primarily responsible for stimulating skeletal muscle protein synthesis and growth. The more nuclei you have, the greater your growth potential.

Sounds important, right? Sure enough, research has shown that individuals who plateau in their training can’t adequately activate satellite cells. To tap into this critical cell population for growth you have to maximize eccentric loading.

It is well known that the negative or lowering phase of a lift causes the most micro trauma/damage to your muscle tissue. While doing this constantly would result in overtraining, performing slow negatives for a few training sessions in a cycle may be extremely beneficial for muscle growth.

For size, accentuating the eccentric (going slow while tensing the target muscle as hard as possible) is the type of muscle action that has the greatest impact on mTor activation. This is an essential step toward maximizing protein synthesis and muscle growth. This is the main reason why accentuating the eccentric will lead to more muscle growth. Of course, a slower eccentric also leads to more muscle fatigue, which is another form of growth stimulus.

Also, eccentric training is well known for strengthening tendons. It is commonly used to rehabilitate ruptured tendons, but including eccentric training in your program can help you prevent such an injury. Thicker and stronger tendons can store more potential energy during the stretch reflex and this can greatly increase strength and power.

For strength and performance, it’s simple: the eccentric strength represents your potential strength improvement: the higher your eccentric strength is, the higher is your potential to increase concentric strength. For performance, it is also important to note that the stronger you are eccentrically, the faster you can switch from eccentric to concentric. When sprinting this means that you will be able to switch from absorbing your body weight when you step on the ground to propelling yourself forward. This means running faster. It also means that you will be more efficient when changing directions.


The fact is, that you are much stronger when you lower a weight (eccentrically) than when you lift a weight (concentrically), and the difference is around 30 – 50% (Duchateau & Enoka, 2015).

If we look at the force-velocity relationship (see below), we can start to understand why many strength coaches recommend lowering loads slowly under control in the eccentric (lengthening) phase of normal strength training.


If we want to lift the same weight in both concentric and eccentric phases (as most people do, most of the time), then we need to manipulate the force-velocity relationships so that the eccentric is harder than it should be.

Lowering under control is one way of doing that. Slow eccentrics require you work harder against what is basically a comparatively much lighter weight. This is why lowering slowly is often recommended during normal strength training, instead of lowering quickly.

Another difference between eccentric and concentric motions is that the eccentric part of a lift requires less energy (or ATP) to complete. This is important because it means you can perform more work eccentrically, which has implications for body composition strength and size gains. Upon reaching fatigue in the concentric part of a lift, the fibers physically “lock up” due to insufficient ATP. If an eccentric action is then performed, small tears occur in the muscle, requiring muscle remodeling and growth.

Eccentric-only training

In studies that have compared eccentric-only and concentric-only training, eccentric-only is far superior for producing muscle damage and hypertrophy. This is because the eccentric motion damages the myofibres and it preferentially recruits fast-twitch fibers. This means there is a greater amount of stress per motor unit with eccentric exercises, producing greater muscle growth.

Studies comparing the effects of slow and fast eccentric-only training show that faster (i.e. heavier) eccentric-only training leads to greater gains than slower (i.e. lighter) eccentric-only training.

Chances are, this is because lowering a weight slowly requires you to use lighter loads, while lowering a weight faster allows you to use much heavier loads. And heavier loads will always make you stronger, probably because they involve greater mechanical loading. Whether the strength gains are mediated solely by greater gains in muscle size, or by other (peripheral and central) changes as well, is less clear.

So if you implement eccentric-only exercises like negative pull-ups, don’t go “too slow”.

I’m not suggesting you do eccentric only training, though. I’m suggesting you take advantage of your body’s potential to handle more weight while still doing the full movement. Higher intensity means greater stress, which means greater adaptation. Here’s the beauty of that – the anabolic response from the heavy loads forces greater recruitment of muscle fibres.


Spend too much time worrying about time under tension and you’ll lose focus on what really counts when it comes to building muscle — that you need to do more work this time than you did last time.

Try to see the whole picture and use tempo and TUT as one of your tools to build your workouts and to avoid plateaus.



— EnCORE Coaching – Personal trainer Waasland —


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