Speed ​​loss and hypertrophy: what threshold to use in VBT

Updated on 26 de June de 2026 by Adrián Escobar Morales

One of the most frequently asked questions among trainers who use VBT is this: How much should I drop the speed on each set to maximize hypertrophy? For years the answer was vague — “it depends on the goal.” Today science has a much more concrete answer, and it has direct implications for how you program strength training.

The key is in the concept of speed stall threshold — the percentage of speed drop compared to the first repetition of the series that you decide to tolerate before stopping. And the evidence accumulated in recent years shows that this parameter is one of the most powerful regulators of the adaptations you obtain from training.

What is speed loss and why does it matter?

When you perform several repetitions in a row with the same load, the speed of execution drops progressively as fatigue accumulates. If you perform your first squat repetition at 0.65 m/s and the fifth repetition at 0.46 m/s, you have accumulated a speed loss of 29%.

The sports encoder allows you to monitor this drop in real time, repetition by repetition. This gives you control over the effective volume of each set that is not possible with any other method — not with RPE, not with reps in reserve, not with 1RM percentage.

The question is: What happens physiologically when you allow different levels of speed loss? And how much do you have to lose for optimal muscle growth?

The reference study: VL20 vs VL40

The most cited study on this topic is that of Pareja-Blanco et al., published in the Journal of Applied Physiology, where they compared two groups that trained squats for 8 weeks with the same relative load but different speed loss threshold:

• VL20 Group: They stopped the series when the speed dropped by 20%.
• VL40 Group: They stopped when the speed dropped by 40% — that is, they got much closer to failure.

The results were revealing:

• The VL40 group performed a 40% more total repetitions than the VL20.
• Both groups won maximum force similarly — 1RM improved similarly in both.
• The VL40 group achieved increased hypertrophy of the vastus lateralis, with a greater increase in the cross-sectional area.
• However, the VL20 group had significantly greater improvements in CMJ (9.5% vs 3.5%) and in sprint speed.

In other words: more loss of speed favors muscle growth, but harms explosive performance. Less loss of speed better preserves jumping and sprinting ability, with equivalent strength gains.

Confirmation of the meta-analysis: the relationship is dose-response

In 2023, Jukic et al. published in Sports Medicine the most comprehensive meta-analysis to date on the effects of velocity loss thresholds in strength training, analyzing both acute responses and chronic adaptations.

Their conclusions reinforce and expand previous findings:

• There is a dose-response relationship between cumulative speed loss and training volume, neuromuscular fatigue, blood lactate and perceived exertion — the greater the speed loss, the more of all of this.
• Speed ​​stall thresholds They do not affect gains in maximum strength or muscular endurance. — no matter how much you drop speed, 1RM improves similarly.
• The high thresholds are tops for hypertrophy.
• Low thresholds are superior for explosive performance: vertical jump, sprint speed and speed against submaximal loads.

This last point is critical for coaches working with athletes who need strength and power at the same time — the classic combination of the team athlete or the combat athlete.

The practical table: which threshold to use depending on the objective

Why this happens: the physiological explanation

Understanding the mechanism helps to better apply the principle. When you allow a high speed loss you are accumulating more neuromuscular fatigue and more metabolic stress per set. That means:

• Greater recruitment of type II fibers As the slower fibers fatigue — the fast fibers are forced into action to complete the last few reps.
• Increased muscle damage and anabolic response — the mechanical stress accumulated in those last slow repetitions is a powerful stimulus for protein synthesis.
• Greater accumulation of metabolites (lactate, inorganic phosphate) that act as muscle growth signals.

The problem is that that same accumulated stress interferes with the ability to produce force quickly — exactly what you need to jump, sprint or perform explosive gestures. The last repetitions of a series with high speed loss train you to move slowly, and that takes a toll on the nervous system that takes days to recover.

That is why the VL20 achieves better CMJ performance than the VL40 despite doing many fewer repetitions — the repetitions it does are of higher mechanical quality and do not generate the fatigue that interferes with explosive performance.

The most important implication: strength does not distinguish

Perhaps the most surprising finding of all this evidence is that 1RM improves similarly regardless of speed loss threshold. Whether you stop at 20% or 40%, maximum force increases in equivalent proportions.

This has an enormous practical consequence: you don’t need to come close to failure to gain strength. You can get the same strength gains with much less accumulated fatigue by simply stopping earlier in each set. This frees up recovery capacity for the rest of the training and for sports performance.

If your goal is primarily strength — not hypertrophy or explosive performance — a threshold of 15-20% is probably the sweet spot: enough stimulus to adapt, with minimal fatigue necessary.

How to apply it with the ADR Encoder

This is all theoretically interesting but only applicable if you have a way to measure speed loss in real time during training. That’s where the ADR Encoder comes into play.

The app ADR System shows the speed of each repetition in real time and automatically calculates the loss of speed compared to the first repetition of the series. When the fall reaches the threshold you have defined, you stop — without counting repetitions, without guessing the effort, without depending on subjective perceptions.

A practical protocol to get started:

1. Define your goal for that training block — hypertrophy, strength or power.
2. Select the corresponding threshold according to the table above.
3. Set the load between 65-85% of estimated 1RM — the range where speed loss is most informative.
4. Perform each repetition with maximum speed intention.
5. Stop the series when the ADR Encoder indicates that you have reached the threshold.

With this system, the volume of each series is self-regulated based on the athlete’s actual state that day — if he is more tired, he will reach the threshold sooner and do fewer repetitions. If it’s cooler, you’ll be able to do more before you reach it. The stimulus is always appropriate, not estimated.

Conclusion

Loss of speed is not just an indicator of fatigue — it is a programming variable with specific and predictable effects on training adaptations. More speed loss produces more hypertrophy but interferes with explosive performance. Less loss of speed preserves jumping and sprinting ability with equivalent strength gains.

Knowing this principle and having a tool that allows you to apply it accurately fundamentally changes how you can program strength training for different goals and different times of the season.

Literature

1. Pareja-Blanco, F. et al. (2017). Effects of velocity loss during resistance training on athletic performance, strength gains and muscle adaptations. Scandinavian Journal of Medicine & Science in Sports, 27(7), 724–735. See in PubMed →
2. Jukic, I. et al. (2023). The acute and chronic effects of implementing velocity loss thresholds during resistance training: a systematic review, meta-analysis, and critical evaluation of the literature. Sports Medicine, 53, 177–214. See study →
3. Andersen, V. et al. (2024). Resistance training with different velocity loss thresholds induce similar changes in strength and hypertrophy. Journal of Strength and Conditioning Research, 38(3), e135–e142. See study →
4. Refalo, M.C. et al. (2023). Influence of resistance training proximity-to-failure on skeletal muscle hypertrophy: a systematic review with meta-analysis. Sports Medicine, 53(3), 649–665. See study →

Adrián Escobar Morales