Velocity drops at a consistent rate as you do more reps in a set.
But how much velocity loss should you be training too?
This guide should give you a rough estimate of how much fatigue you might want to be accumulating - or not accumulating - across a set.
What is velocity loss?
Before we worry about the actual cut offs to hit, a quick crash course on recording velocity loss.
As we complete more and more reps in a set, our ability to maintain the same bar speed reduces. We fatigue.
With velocity tracking, it's possible to precisely calculate and monitor the amount of fatigue across a set. The tried and true method for calculating velocity loss is to take your best (typically the first or second) rep and calculate the difference to your slowest (usually last) rep of the set.
This drop in velocity assumes and high intent on every rep, without these don't bother with intra-set fatigue tracking.
If we assume sound technique and a high level of intent across every rep this gradual drop in velocity indicates how much fatigue is built up.*
From there, it’s possible to autoregulate the number of reps prescribed by limiting the amount of fatigue % an athlete is allowed to work into.
"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%"
*If the velocity graph is all up and down across a given set don't discount the impact of technique, lack of focus or mixed intent as also impacting the velocity outputs.
So what percentage should you work with?
Grinding into this much of a velocity drop is tough going.
For many exercises with at a reasonable amount of weight, a 40% drop in velocity is often associated with technical failure for many exercises. (1)
This type of training is suboptimal for developing strength and power and typically leads to high fatigue accumulation.
We will explore the research in a second but the key takeaway
Avoid training up to or beyond 40% fatigue on a regular basis
This is a high volume training prescription.
30% is a good number to work around for when hypertrophy is a target, or you are in a high volume accumulation block of training such as an off-season/GPP phase. 30% also works great to control rep output on accessory or secondary movements. This works both ways, motivating more casual lifters to squeeze our more reps than they might self select and holding back hard workers from grinding out harder than might be neccessary.
20% has a bit of a magical aura to it.
Probably due to the amount of research that has used 20% as the "low volume" group in studies, a 20% cut-off has become one of the most common training cut off points. And for great reason, it works.
In fact two great studies (2), (3), looked at 40% velocity loss compared to 20% over a block of training.
The first study (2) measured an exhaustive list of adaptive factors and showed that the 20% group had a significant advantage.
All while doing 40% less total reps across the eight weeks.
Some of the differences after only eight weeks are huge, especially given the 20% fatigue group did 40% less work.
- 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)
The second study (3), focused directly on upper body power in a a group of elite kayakers over 12 weeks of bench press and row training.
Again, the result was night and day, with the 40% fatigue group doing almost twice as much work, but basically making zero improvement over the training block.
Taken collectively, it seems restricting velocity losses to only 20% is great cut-off for hitting the gains sweet spot.
hard enough to promote adaptations and force growth, but not so hard that you become a leg-day DOMS meme.
Even if they don't use velocity based training many powerlifting and S&C coaches have independently and intuitively built entire training systems work around this 20% velocity cut off.
They call it RPE 8
This is intuitively smart training, and it takes many forms:
- 8 reps at a 10RM in a volume phase
- A crisp triple with a 5RM load
- Multiple singles with your 3RM
We might be splitting hairs now with this level of granularity, but there is some value for the big picture.
F. Pareja-Blanco (4) compared 30% and 15% velocity cut offs in soccer players for their in gym training. both groups saw similar strength gains over the six weeks, while the 15% group had a greater jump improvements.
When the findings from these three studies (2-4) are combined the following rough guidelines could be extrapolated:
- 40% in-set fatigue is the point where the proximity to failure begins to have a negative effect on strength and power adaptations. Avoid training this hard too often
- 15-30% is a optimal zone for regular strength training. This wide range gives plenty of room for volume adjustment over training blocks.
- 15-20% might be more optimal for power adaptation and maintenance of jump performance in season.
10% is a strict cut-off, and if used incorrectly or too frequently this low of a volume may have negative effects on your progress. I mean you still have to do some work!
10% can have value when used intermittently in your training. I see two unique, high value applications.
Power focused sets
Power training is about quality.
If you want to jump higher, you need to practice jumping higher, that means intent and output must be pretty maximal. No one developed elite level bounce without some pretty high power exercises.
Fatigue - both acute and chronic - is the enemy of this high quality power development, so multiple short sets are significantly more valuable than longer grinding sets.
One of the best strategies to increase power output, without compromising session density is to use cluster sets.
Tufano and his team highlighted this effect beautifully in 2016 (5):
Tapering and deloading
The second way to utilise a 10% cut-off is during a taper.
In tapering the goal should be to maintain as much intensity as possible while restricting volume, creating the space for supercompensation and peaking to occur.
A 10-14 day reduction in volume seems to be the gold standard (6), and there aren't many easier ways to implement this than by tightening up the in set fatigue.
Keep hitting the same weights but instead of working in the 20-30% range tighten up to 10%.
- RPE 8 becomes 6.5
- Sets of 5-6 become 2-3
Try not to mess with many other variables, keep rest periods and session lengths the same, these sessions should leave you feeling primed and fresh, not beaten and tired.
The big takeaways when using velocity loss:
- 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.