Most lifters judge a hard set by how close it comes to failure, but Somak Sarkar stresses that this assumption deserves a closer look. A growing body of research suggests that ending a set while the bar is still moving at a good speed can build strength just as well, with less fatigue and better power.
The tool behind this research is simple: measuring how much the bar slows down from the first rep to the last. That drop, called velocity loss, is becoming one of the most useful numbers in strength training.
What Velocity Loss Means
Velocity loss is the percentage by which bar speed falls across a set. The first rep is usually the fastest. As fatigue builds, each rep moves a little slower until the lifter can no longer complete another one.
A small sensor on the bar or a phone app can track this rep by rep. If the first rep moves at 0.80 meters per second and a later rep drops to 0.64, the set has reached a 20% velocity loss. Lifters and coaches can set a limit in advance and end the set once that limit is reached.
This turns a vague instruction like stopping a couple of reps short of failure into something measurable. Instead of guessing how many reps are left, the bar shows how much fatigue has built up.
The Study That Changed the Conversation
A 2017 study published in the Scandinavian Journal of Medicine & Science in Sports tested this idea directly. Over eight weeks of squat training, one group of young men ended each set at a 20% velocity loss, while another group continued until speed had dropped by 40%.
The results surprised many coaches:
- Strength gains were similar in both groups, even though the 20% group performed about 40% fewer repetitions.
- Jump performance improved more in the group that stopped earlier, rising about 9.5% compared with 3.5%.
- Muscle growth was somewhat greater in parts of the thigh for the group that pushed further.
- Fast-twitch fiber characteristics were better preserved in the group that stopped earlier, while they declined in the group that trained closer to failure.
In other words, the extra reps added fatigue and some size, but not more strength, and they came at a cost to explosive power.
What the Wider Research Shows
A single study can only say so much, so researchers have since pooled the evidence. A 2022 systematic review and meta-analysis in Sports Medicine, led by Ivan Jukic with colleagues including Eric Helms, examined 18 short-term studies and 19 longer training studies on velocity loss thresholds.
The review found a consistent pattern:
- Strength gains were similar regardless of the velocity loss threshold used.
- Jump performance tended to be better with lower velocity loss thresholds.
- Muscle growth tended to increase as velocity loss thresholds went up.
The message is not that one threshold is best for everyone. Different stopping points favor different goals.
Matching the Stopping Point to the Goal
Velocity loss thresholds give lifters a way to shape their training around what they want most:
- For Power and Speed: Lower thresholds, often around 10 to 20%, keep each rep fast and limit fatigue. This suits athletes in sports that rely on jumping, sprinting or quick changes of direction.
- For Strength: Moderate thresholds appear to work well, since strength gains look similar across a wide range of stopping points. Stopping earlier can save energy for more sets or other training.
- For Muscle Size: Higher thresholds, which bring sets closer to failure, tend to favor growth, though recovery demands rise as well.
For many recreational lifters, a moderate approach offers a practical balance between progress and recovery.
Why Less Fatigue Can Mean Better Training
Fatigue is not only felt during a workout. Sets taken very close to failure can leave lifters sore and drained for days, which can lower the quality of the next session.
Stopping earlier keeps more energy in reserve. That can allow more frequent training, better technique on every rep, and fewer sessions spent grinding through heavy fatigue. For athletes balancing practices and games, that reserve can be the difference between arriving fresh for competition or arriving worn down.
Using the Idea Without a Sensor
Not every lifter has a bar speed tracker, and the principle still applies without one. Many coaches use reps in reserve, which means ending a set with one, two, or three good reps still possible.
A few simple cues can stand in for velocity data:
- Watch for a visible slowdown. When a rep moves noticeably slower than the first, fatigue is building quickly.
- Notice changes in form. A shift in bar path, depth or posture often signals the set should end.
- Film a set occasionally. Video makes changes in speed easier to see than they are in the moment.
These methods are less precise than a sensor, but they bring the same idea into any gym.
Rethinking What a Hard Set Looks Like
Training to failure will always have a place, especially for lifters focused on muscle size. But the research on velocity loss makes a strong case that every set does not need to end in a grind.
For many lifters, the smarter goal is to stop when the bar says the work is done. Strength keeps improving, power stays sharp and recovery becomes easier to manage over the long run.