Rate of Force Development (RFD): How to Train Explosive Strength

Rate of force development (RFD) is how quickly you can build force once a muscle starts to contract. It is the change in force divided by the change in time, and it tends to matter most in the first 50-100 milliseconds. You can improve it with explosive training such as jumps and throws, with heavy lifting, and most sensibly by combining both with the intent to move fast.

This guide is a deep dive inside our complete guide to maximal strength and powerlifting science. We will cover what RFD is, what happens in your nervous system in those first fractions of a second, and how to train it without wrecking your lifting. Where studies disagree, I will say so.

What is rate of force development?

Maximal strength asks “how much force can you produce, given all the time you want?” RFD asks “how much can you produce in a very short window?”

That distinction matters because many real movements are quick. A jump take-off, a sprint stride or a fast bench press off the chest gives your muscles a limited time to build force. If force rises slowly, you may not get to use your full strength before the movement is over.

Researchers usually measure RFD as the slope of the force-time curve over fixed windows, such as 0-50, 0-100 or 0-200 ms, often during a maximal isometric push. A review by Maffiuletti and colleagues notes that RFD is quite difficult to measure in a valid and reliable way, which is a polite warning not to over-read any single number from a gadget (Maffiuletti et al., 2016).

What controls RFD in the first 50-100 milliseconds?

The same review concluded that RFD seems to be mainly determined by the capacity to produce maximal voluntary activation in the early phase of an explosive contraction (the first 50-75 ms), particularly through increased motor unit discharge rate (Maffiuletti et al., 2016). A motor unit is one motor neuron and the muscle fibres it controls. Discharge rate is how often that neuron fires.

In plain gym language: early RFD depends on how quickly and how hard your nervous system turns the muscle on. Later in the contraction (roughly beyond 100-200 ms), maximal strength and muscle properties are generally thought to play a bigger role.

That is why a stronger muscle is not automatically a faster one. For the wider picture of how your nervous system limits strength, see our guide on neuromuscular foundations of maximal strength, and for the fibre-type side, slow vs fast-twitch muscle fibres.

Does heavy lifting improve RFD?

Sometimes, and the studies are not unanimous.

What study A found. Aagaard and colleagues trained 15 men for 14 weeks (38 sessions) with heavy-resistance strength training. Maximal isometric strength rose, and RFD in the first 30, 50, 100 and 200 ms rose too. Muscle electrical activity in the early phase of contraction increased substantially, which they interpreted as enhanced neural drive (Aagaard et al., 2002).

What study B found. Del Vecchio and colleagues examined motor unit data before and after 4 weeks of strength training. Maximal force increased, but RFD did not change, because the number of motor units recruited per second and their initial discharge rate during rapid contractions were unchanged (Del Vecchio et al., 2022). They concluded that increases in the recruitment speed of motoneurons would be needed to raise RFD.

Why they may differ. The first study ran for 14 weeks, the second for 4. The training also differed (heavy dynamic work versus a 4-week isometric programme), and so did the way contractions were performed. Both are small lab studies in men, so I would not draw a hard line.

Practical takeaway. Heavy lifting can improve RFD over a longer period, but a short block of strength work may raise maximal force without improving the early rise. If speed matters to you, include some work where you deliberately move fast. The Maffiuletti review states that RFD can be improved by both explosive-type and heavy-resistance training, mainly through improved rapid muscle activation (Maffiuletti et al., 2016).

How do ballistic exercises train explosive strength?

A ballistic exercise lets you accelerate the whole way and let go or leave the ground. In a normal bench press or squat, you must slow the bar near the end so you do not drop it or fall over. With a jump squat or a medicine ball throw, you can keep pushing until the last moment.

Examples that work well in a normal gym:

• Jump squats (bodyweight or a light load)
• Box jumps (step down, do not jump down)
• Medicine ball chest passes or slams against a wall or the floor
• Kettlebell swings, which are fast hip drives with the load travelling in an arc
• Explosive push-ups where your hands leave the floor

One practical detail from the research: in a 10-week study of weightlifting-style training that included jump squats, results depended on how strong people were to start with. The stronger group saw a very large improvement in RFD at 20% of squat 1RM at the mid-point, while the weaker group improved more slowly and showed a more force-dominant adaptation (James et al., 2022). It was a small study, so treat it as a hint rather than a rule.

Do plyometrics improve explosive power?

For jumping, yes. A meta-analysis of 26 studies in healthy people found that plyometric training improved vertical jump height by about 4.7% in the squat jump, 8.7% in the countermovement jump, 7.5% in the countermovement jump with arm swing, and 4.7% in the drop jump (Markovic, 2007).

Two caveats. First, this was a review of studies in healthy individuals of mixed training levels, not elite powerlifters. Second, jump height is not the same as RFD, so these figures show that jump ability improved, not that early force rose by a particular amount.

Should you train heavy, fast, or both?

The most useful framing is a mix.

A review by Suchomel and colleagues suggests that weaker athletes should focus on developing strength before emphasising power-type training, while stronger athletes may begin to emphasise power-type training while maintaining or improving strength. They also note that programming which combines heavy and light loads may improve strength and underpin other strength-power characteristics (Suchomel et al., 2018).

That fits what many coaches do. Early on, building a solid squat usually gives you more to work with than a jump program. Later, speed becomes the thing that separates two lifters of equal strength.

A 2026 meta-analysis of 19 studies (537 participants, from sedentary to highly trained) compared complex training (heavy lifts combined with ballistic work in one session) with ballistic training alone. Complex training produced larger gains in squat 1RM, squat jump and 10 m and 40 m sprint, while 5 m and 20 m sprint, change of direction, countermovement jump and jump power improved similarly. The certainty of evidence was low or very low, and longer programs (over 7.5 weeks) seemed to favour complex training (Thapa et al., 2026). In other words, combining heavy and fast work is a reasonable bet, though not a proven formula.

Method	What it trains	Example	Good for
Heavy strength	Maximal force, later-phase force	Squat, 3-5 reps	Everyone, especially beginners
Ballistic	Fast force, early activation	Jump squat, med ball throw	Intermediate and advanced lifters
Plyometric	Stretch-shortening cycle, stiffness	Box jump, depth landing	Athletes with a strength base
Isometric ballistic	Early RFD in a set joint angle	Fast push into pins	Low-fatigue options, joint-specific

Does intent to move fast matter with heavy loads?

Even with a heavy load that moves slowly, trying to move it fast changes the output. In a randomized crossover study of 14 recreationally trained men, squatting 4 reps at a 5RM load with maximal intended speed raised half-squat peak power, peak velocity and maximum RFD compared with a controlled tempo. However, neither condition significantly improved later countermovement jump performance, though some individuals showed small jump gains after the fast version (O’Grady et al., 2021).

So intent seems to change the lift you are doing, but it is not a trick for boosting the next exercise. We unpack the concept in intent to move explosively.

Another related option is ballistic isometrics. A narrative review reported that performing isometric strength training in a ballistic manner can maximise the improvement of RFD (Lum et al., 2019). That can be useful if you want low-fatigue work at a specific joint angle, but it is a narrative review, so take it as a suggestion.

Does the phase of RFD you train matter?

It can. In a study of 20 healthy men, eight weeks of fast-velocity eccentric knee extension training (three days a week) raised maximal isometric torque by 28% and early-phase RFD (the 0-50 and 50-100 ms windows) by about 30%, with no change in late-phase RFD (Oliveira et al., 2016). That suggests early and late RFD can respond differently to different training. It is one small study in active men, so the numbers will not generalise to everyone.

Elastic tissue plays a role in quick movement too, which we cover in tendon stiffness and the stretch-shortening cycle.

How to add RFD work to your week

A practical starting template, based on coaching convention and the principles above:

1. Warm up fully, then do explosive work first.
2. Pick 1-2 ballistic exercises, 3-4 sets of 3-5 reps with 2-3 minutes rest.
3. Move on to heavy strength work (for example 3-5 sets of 3-6 reps).
4. Do accessories last.
5. Run it for 6-8 weeks, then reassess.

If you do not know your working weights, use our 1RM calculator to estimate them, and our leg day plan shows where jumps can slot in.

Who should be careful?

Landing from jumps loads your knees, ankles and Achilles tendons. If you have current joint or tendon pain, a history of surgery, or you are returning from injury, speak to a doctor or physiotherapist before adding plyometrics. Begin with low-impact ballistic work such as medicine ball throws and kettlebell swings, and build up volume slowly. Pregnant lifters, people with heart conditions and older adults should also get individual advice first, because most of the research here is in healthy, younger people.

The bottom line

Rate of force development is about how fast you build force, and it depends heavily on how quickly your nervous system switches the muscle on in the first 50-100 ms. Heavy lifting can raise it over time, but the evidence is mixed, so adding jumps, throws and fast lifts is a sensible move once you have a base of strength. Keep the sets short, fresh and fast, and let your heavy training stay in the plan. For where this fits with the rest of your programme, go back to the maximal strength and powerlifting guide, and for the difference between getting stronger and getting bigger, read strength gains vs muscle growth.