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Velocity loss threshold: Fatigue percentage guidelines for VBT

Assuming you try to lift every rep with high intent, fatigue will build up across a set leading to slower barbell velocities the longer the set goes. Eventually, we reach a point where we cannot lift the barbell again, passing the point of failure as barbell velocity reaches our minimum velocity threshold.

We measure this proximity to failure with velocity loss, taking the difference between your fastest rep in a set (typically rep 1 or 2) and the last rep of the set. Most often a velocity loss of 40% is considered the point of failure for lower body lifts such as squats and deadlifts, while a 50% velocity loss threshold is commonly the failure point for upper body lifts.

If 40-50% velocity loss is the failure point, what velocity loss should you be training with?⁠⁠

This article explores ways to measure your velocity loss in the gym and gives you some guidelines of how to program with velocity loss thresholds to optimise your training sessions, autoregulate your sets and make greater gains in strength and power.

How do you measure velocity at the gym?

Firstly, in order to train with the velocity loss method, you will need an accurate way to measure the velocity of your repetitions. The best and most affordable way to do this is with the Metric VBT application.

Metric works by recording video of your set, providing audible real-time feedback on velocity and velocity loss during your sets helping you determine when you have reached your desired velocity loss target. Metric uses computer vision to track bar speed without needing any additional devices. It's available on iPhone and iPad as a free to download and there are Pro and Teams plans available if you want to subscribe and take your VBT even further.

Get the Metric VBT app here →

What is the velocity loss in training?

As we complete more and more reps in a set, our ability to maintain the same bar speed reduces. We fatigue. One way to measure velocity loss and exertion in training can be with a subjective value such as RPE or RIR, another more objective approach is with velocity tracking. With velocity tracking t's possible to precisely calculate the amount of fatigue we experience across a single set, relative to our maximum potential.

Some approaches to velocity loss is to measure velocity loss between the first and last repetition of the set. My preferred approach is to take the fastest rep of the set, no matter when it occurs and calculate the difference from this rep to your last rep for a true measure of velocity loss. When the first rep is the fastest (as it often is) both methods give the same result, but on certain exercises, it is common to deliberately (or accidentally) slow down the first rep, by using best rep velocity we get a better indication of your maximum velocity for that given set.

It's important to note that any drop in velocity assumes high intent on every rep, without good intent intra-set velocity loss methods will not work.
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This image is licensed under a Creative Commons Attribution 4.0 International License.


Why train with a velocity loss threshold

Velocity loss thresholds are a powerful and well-researched way to improve training outcomes, there are a number of strategies to apply these thresholds in your training.

Control proximity to failure

Training with a velocity loss threshold allows athletes to precisely control their proximity to failure. By setting a specific velocity loss threshold, athletes can terminate a set when reaching their desired level of fatigue and optimise training effectiveness for their current training focus or time of season.

Push your limits

A velocity loss threshold enables athletes to push their limits in a controlled and measurable way. It provides a clear target for each set, encouraging athletes to maintain a high velocity to get the most reps out while avoiding the velocity loss threshold​. Opening up to higher percentage values (30% or above) gives athletes a safe way to progressively challenge themselves and uncover higher levels strength than they might have thought possible.

Autoregulate training based on real-time readiness data

Autoregulation is a key benefit of using a velocity loss threshold. It allows training intensity to be adjusted in real-time based on the athlete's current performance and readiness, which is crucial for optimizing training outcomes​​. By making training more dynamic and flexible it aligns training stress with the athlete's current physical state, reducing the risk of overtraining and enhancing overall training efficiency to account for an individuals unique rate of recovery and strength progression.

Applying velocity loss thresholds

Now that we know how velocity loss (% fatigue) is calculated, and why we might use it in a broad sense, let's look at how to use real-time feedback from the Metric VBT app (or any other velocity based training device) incorporating velocity loss thresholds into our training as a way of autorgeulating training and improving the performance adaptations.

Velocity stop points

A stop point or velocity loss cut-offs is a brilliant way to to autoregulate the number of reps that an athlete will do, and control proximity to failure.⁠⁠ An athlete or coach would set a velocity loss value in the app's real-time feedback settings and then perform their set as normal, Metric will then announced the velocity loss value as you approach or pass the threshold. At that point the set ends. This is called an open set, or dynamic rep count.

As an example you might apply this like the following:

  • "Let's lift 155kg but stop once you reach 18-20% fatigue"⁠⁠
  • "For this drop set, you need to keep lifting at maximum effort until your velocity drops at least 35%"⁠⁠

The higher the % velocity loss that you set as your threshold the harder the set andthe close you are going to failure. Velocity loss percentages fit into four categories; training to failure, hard training, sweet spot training, tapering/power training.

Training to failure: 40% velocity loss - 9.5+ RPE

Grinding into this much of a velocity drop is tough going.

For sets of 3-10 reps, a 40% drop in velocity or more is often associated with technical failure. This level of training stress is tough, and should be used strategically and sparringly. Training to this level of exertion is linked to lower strength gains.

We explore the research here but the key takeaway is:

Avoid training up to or beyond 35% velocity loss on a consistent basis. The fatigue accumulation almost always outpaces the recovery rate.
40% velocity loss chart with VBT

Challenging training: 30% velocity loss - 8.5-9 RPE

This is a high volume training prescription. A little short of complete failure, sets this tough are still going to be challenging and might be used in high-volume or off-season/GPP training phases.

30% is also a good velocity loss threshold to use for athletes who you think might be holding back somewhat in their training. Give them a 30% velocity loss target and have them continue repping out sets until they hear the 30% number announced by the app. I did this on my squats recently and turned a planned set of 6 into 10 reps - clearly I had not beeng pushing these hard enough in my workouts!

30% velocity loss chart with VBT

Optimal strength building: 20% velocity loss - 7-8 RPE

20% velocity loss is the sweet spot. Hard enough to create adaptations and force growth, but not so hard that you can't recover and supercompensate from the stress in time for your next workout in 48 hours time.

Even before velocity loss tracking became widely adopted many athletes and coaches in powerlifting, weightlifting, and strength & conditioning had intuitively worked out that this tough-but-not-impossible level of training was where athletes largely thrive.

This is intuitively smart training, and it takes many forms:

  • 20% velocity loss
  • 8 RPE
  • 8 reps at a 10RM in a volume phase
  • Triples with a 5RM load
  • Multiple singles with your 3RM

Plenty of research has looked into this relationship between velocity loss, proximity to failure and training outcomes. Repeatedly, 15-25% velocity loss leads to superior outcomes versus groups that trained to 30-40% velocity loss.

Adaptations with 205 vs 40% velocity loss. F. Pareja-Blanco 2016

One great example of this was a 2016 study from Pareja-Blanco (2016) highlights the differences that only eight weeks of training with 20% vs 40% velocity loss can have.

  • +7kg on 1RM (19 vs 12kg)⁠
  • +3cm on vertical leap (4cm vs 1cm)
  • +11% increase in TIIA fibre ratio (the 40% group actually shifted down in TIIA composition)⁠

Thes findings are consistently repeated in training studies, and the thing I find especially compelling is that the 20% fatigue group almost always gets these better training outcomes despite doing much less total training volume than the 40% groups - showing that it's not always about the amount of work you do, but about the quality and type of that training work.

You can read more about this research and the training to failure phenomenon in this blog →

Tapering and power training: 5-15% velocity loss - 6-7 RPE

Training with a 5-15% velocity loss target optimally balances intensity and volume for power development and tapering.

For power training, this tight threshold ensures maximal output and quality in each exercise, while minimising fatigue accumulation - something crucial for enhancing power. One great way to do this is with short, intense cluster sets to maintain time efficiency and minimise fatigue.

Velocity loss thresholds this low are not optimal for developing strength, but they are good for tapering in the lead up to a competition. In tapering and deloading the goal should be to maintain as much intensity as possible while restricting volume, creating the space for supercompensation and peaking to occur. A 10% velocity loss threshold allows lifters to maintain a high % of 1RM while shortening sets and reducing overall volume, crucial for allowing peak strength levels to come through.

Using this strategy in a powerlifting taper for example can be as simple applying a 10% velocity loss threshold to reduce total rep counts while keeping other training variables constant, ensuring sessions leave athletes feeling primed and strong rather than fatigued.

10% is a great cut off to use for power based training but it is a strict cut-off, and if used incorrectly or too frequently this low of a volume may have negative effects on your progress in strength and hypertrophy training. I mean you still have to do some work!

10% velocity loss chart with VBT

Key takeaways to the velocity loss method in training

  • Train hard, but also train smart, more sets are better than squeezing every drop out of every rep
  • Grinding reps aren't as valuable as they are exhausting.
  • RPE 8 is golden. Leave two in the tank
  • Power is incredibly sensitive to fatigue, when in doubt do less, but do it well.

When velocity loss thresholds don't work as well

Velocity loss thresholds can be mixed in their effectiveness with heavy strength sets of 1-2 reps, because the rep numbers are so low, you might go from the second rep at a comfortable 15% fatigue and then the third spikes right up to 35% or higher. On these heavy sets reflect on fatigue after the set, but for the lifter in the middle of that set a subjective RPE systems might be more practical than using a real-time velocity loss threshold as it can be hard to hit the target consistently. Be sure to experiment and see what works for you and your trainign style.

Record velocity loss with MetricVBT

If you want to try out this velocity loss approach in your training, I suggest checking out Metric VBT.

I am part of the team that is building MetricVBT, an app that provides real-time velocity loss feedback during training. It is available for free on the App Store, you can download it from the Metric website at this link.

Metric VBT a free app for tracking your bar speed in the gym
Metric VBT a free app for tracking your bar speed in the gym

See also: Why training to failure might be holding you back →

See also: Is training to failure good for you? →

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