Isometrics only won two things: knee torque at 75° and the first step
In short
A pilot study of 17 collegiate athletes compared load-matched isometric and dynamic resistance training over five weeks. The isometric group was statistically ahead on exactly two outcomes: peak knee-extension torque at 75° and sprint speed out of a squat start. Vertical jump showed no between-group difference and isokinetic torque showed no modality-specific superiority. The authors call it exploratory and state that definitive superiority cannot be concluded.
That isometric training builds strength and size is settled ground. The open question is practical: at matched load, is holding better than lifting? This pilot tried to answer it.
The participants were 17 collegiate Kho-Kho players — Kho-Kho is an Indian tag-and-pursuit sport with heavy demands on acceleration — split into nine isometric and eight dynamic. Both completed a five-week program at matched load, with intensity regulated by modality-specific scales: the Isometric Exercise Scale for the holds, Borg CR-10 for the dynamic work.
Why use two different intensity scales?
This is the design detail worth stealing. A hold has no rep count and the bar does not move, so the RPE sense you use for normal sets does not carry across — which is why a dedicated isometric scale exists at all. It is also why guessing at intensity when you bolt holds onto a program is a mistake.
The result: two wins, and that is all
Testing covered knee extension and flexion torque at multiple angles and velocities, sprint performance from a squat start, vertical jump metrics, and reactive strength index. Both groups improved on selected strength and sprint outcomes.
Between groups, only two outcomes separated statistically: peak right knee-extension torque at 75° and initial sprint speed out of the squat start. Both favoured the isometric group.
Nothing else split. Jump height improved within the isometric group, but vertical jump showed no significant group × time interaction, and the isokinetic torque outcomes showed no clear superiority for either modality.
This is what joint-angle specificity looks like
The fact that the win was at 75° specifically is the finding. Isometric gains concentrate near the joint angle you trained and taper off as you move away from it. The absence of a difference across the other torque measures, taken at multiple angles and velocities, is the evidence for that.
The acceleration result reads the same way. The first step out of a squat start is the phase where you produce large force from something close to a standstill — an angle and velocity condition that lines up neatly with what holding trains.
Seventeen athletes, five weeks, one sport. The authors themselves describe it as exploratory and state that definitive superiority over dynamic resistance training cannot be concluded. Treat it as a direction, not a reason to rebuild a program. The strength and hypertrophy case for isometrics is covered separately in isometric training and hypertrophy.
How this applies to the Big 3
The Big 3 are full-range lifts, and a Muscle Index score is built from their 1RM total. Replacing squats or deadlifts with holds is not on the table. Because gains sit near the trained angle, force gained at one position does not transfer wholesale to the lift.
The useful slot is narrow and specific: the sticking point. If you always stall at the same depth in a squat or the same height on a bench, adding holds near that angle as an accessory is close to what this study supports. And once you do, check it against your Big 3. Whether an accessory actually moved the main lift only shows up in the log.
Frequently asked questions
Is isometric training better than conventional lifting?
This study cannot say. In a load-matched five-week comparison, isometrics were statistically ahead on only two outcomes — peak knee-extension torque at 75° and sprint speed from a squat start — with no difference on the other strength and jump measures. The authors state definitive superiority cannot be concluded.
What does joint-angle specificity mean?
It means the benefit of isometric training concentrates near the joint angle you trained. In this study the difference appeared at 75° of knee extension specifically, while the other torque measures taken at multiple angles and velocities showed no advantage for either modality.
How do you set intensity for an isometric hold?
Not with a normal RPE scale. In this study the dynamic group used Borg CR-10 while the isometric group used a dedicated Isometric Exercise Scale, because a movement with no rep count and no bar travel does not map onto the usual sense of effort.
Do isometrics improve jumping?
This study did not show that. Jump height rose within the isometric group, but the group × time interaction for vertical jump was not significant, so the data do not support a difference between the two modalities.
Can you replace squats or deadlifts with holds?
No. The Big 3 are full-range lifts and isometric gains concentrate at the trained angle, so force gained at one position does not carry across the lift. Use holds as an accessory near a sticking point, and verify the effect against your Big 3 numbers.
Source: PubMed