When Good Physiology Gets Buried Under Too Much Jargon
Cal Dietz’s Triphasic Training has had a huge influence on strength and conditioning.
And to be clear, a lot of the actual training methods inside the system are good.
Eccentric training? Useful.
Isometrics? Useful.
Heavy strength training? Obviously useful.
Plyometrics, sprinting, ballistic work, potentiation, different force-velocity exposures? All legitimate.
My issue is not really with the means.
My issue is with what happens when fairly straightforward training concepts get wrapped in layers of terminology, neurological explanations, sequencing rules, and proprietary language that make the system sound far more scientifically established than it actually is.
That is where I think Triphasic Training deserves a serious fact-check.
Because there is a very important distinction:
Research supporting the ingredients does not automatically support the recipe.
That distinction gets lost far too often in strength and conditioning.
1. YES, ECCENTRIC, ISOMETRIC AND CONCENTRIC CONTRACTIONS MATTER
Muscles produce force under eccentric, isometric, and concentric conditions.
These contractions have different mechanical and neurological characteristics, and training can emphasize them differently.
This is not controversial.
Research supports eccentric training, isometric training, and explosive concentric training.
For example, isometric training can improve maximal force, rate of force development, muscle size, and tendon properties depending on how it is programmed (Oranchuk et al., 2019).
So far, so good.
But this basic physiology does not prove that athletes need three dedicated training blocks in the order:
eccentric → isometric → concentric.
That is where evidence starts getting much thinner.
2. THE ECCENTRIC BLOCK
Eccentric training works.
That does not mean you need an “eccentric phase.”
This is a big difference.
There is good evidence that eccentric training can improve strength and muscle architecture.
But a major 2026 systematic review and meta-analysis comparing accentuated eccentric loading with normal constant-load resistance training found something very interesting.
Accentuated eccentric loading increased eccentric muscle activation and made the training feel harder.
But over time, it did not consistently produce better improvements in:
concentric strength
eccentric strength
isometric strength
countermovement jump height
muscle cross-sectional area
fascicle angle
compared with conventional resistance training (Zhang et al., 2026).
If true eccentric overload is not clearly superior to normal resistance training across many outcomes, it becomes difficult to argue that an athlete somehow requires a dedicated several-week eccentric block.
Eccentric training?
Absolutely.
Mandatory eccentric phase?
Not established.
3. SLOW ECCENTRICS
A five-second lowering phase is not the same thing as eccentric overload. I have produced educational webinars on this. This is called TEMPO training.
This gets confused constantly.
If I squat 80% of my 1RM and take five seconds to lower the bar, I am emphasizing the eccentric phase.
But I still have to stand up with the same 80%.
The load is therefore constrained by my concentric strength.
True eccentric loading might look more like:
120% down → unload → 80% up.
That is a very different stimulus.
Tempo is certainly a training variable, but research does not support the idea that dramatically slowing the eccentric portion creates some uniquely superior strength stimulus (Wilk et al., 2021).
Slow eccentrics can be useful.
They can increase time under tension.
They can improve motor control. This is what I do when I am teaching a novice lifter.
They can be helpful during rehabilitation.
But they are not magic.
4. SUPRAMAXIMAL ECCENTRICS
Now we are talking about something more interesting.
Humans can generally tolerate more force eccentrically than concentrically.
So supramaximal eccentric work can expose athletes to forces above their normal concentric strength.
That makes physiological sense.
It may be useful for experienced athletes.
But once again, recent research tells us to be careful.
More eccentric loading does not automatically mean better long-term adaptation.
The 2026 review by Zhang et al. found greater eccentric activation but generally similar chronic strength and jump outcomes compared with conventional training.
So supramaximal eccentrics are a tool.
A potentially useful tool.
But not something every athlete needs. And certainly not something for athletes with a low training age.
5. ISOMETRICS
I like isometrics, not necessarily the idea that an athlete needs an “isometric phase.”
The research on isometric training is quite good.
Heavy yielding isometrics are different from explosive overcoming isometrics.
Long-duration tendon loading is different from short maximal contractions.
These are useful distinctions.
Oranchuk et al. (2019) showed that isometric training can improve maximal strength, hypertrophy, tendon properties, and rapid force production depending on the prescription.
But why do I need to wait until the “isometric block” to train those qualities?
I can use isometrics all year when they solve a specific problem.
I do not need to declare February “isometric month.”
6. ECCENTRIC → ISOMETRIC → CONCENTRIC SEQUENCING
This is the heart of Triphasic Training.
And ironically, it is one of the weakest parts from an evidence standpoint.
The theory is logical enough:
First improve force absorption.
Then improve the transition.
Then improve force expression.
Sounds good. But “sounds good” is not the same as “has been demonstrated.”
I am not aware of convincing controlled research showing that:
eccentric block → isometric block → concentric block produces better sprint, jump, power, or strength outcomes than a well-designed mixed program using all three contraction types concurrently.
That is the study I would want to see. I am also not trusting of this method to try it myself on my own top athletes.
Until then, this is a ‘preferred coaching model.’
Not a direction to where all the evidence points.
7.“CONVERTING” ECCENTRIC STRENGTH INTO CONCENTRIC POWER
This language sounds scientific. It is also overly simplistic.
During sprinting and jumping, muscles, tendons, and joints are doing different things at the same time.
One muscle may be shortening. Another may be lengthening.
A tendon may be storing elastic energy while muscle fascicles remain relatively isometric.
Different joints may absorb and produce mechanical work simultaneously.
Human movement is complicated.
Reducing sport performance to:
eccentric → isometric → concentric
can be useful as a coaching simplification.
But it should not be confused with a complete explanation of biomechanics or motor behaviour.
8. FRENCH CONTRAST TRAINING
French Contrast is one of the more defensible parts of this entire ecosystem.
A typical sequence combines:
Heavy strength exercise
Plyometric movement
Loaded ballistic exercise
Very fast or assisted movement
There is now decent evidence that this can improve explosive performance.
A 2025 systematic review and meta-analysis found that French Contrast Training significantly improved sprint and jump performance (Zhao et al., 2025).
That is meaningful. But there is an important caveat.
The researchers could not establish that French Contrast was clearly superior to conventional complex training.
And that makes sense.
If an athlete does:
heavy strength work,
jumps,
ballistic training,
and high-velocity movements,
we already know those ingredients can work.
French Contrast may be a very good way to organize them.
But again: good organization does not automatically equal unique physiology.
9. THE FORCE-VELOCITY SPECTRUM
Athletes need to produce force under different loading and velocity conditions.
Heavy lifting develops high-force qualities.
Ballistic training develops high-velocity force expression.
Plyometrics train rapid force application and elastic qualities.
Sprinting exposes athletes to extremely high-speed force production.
This is all sensible and well supported.
Research comparing resistance training, weightlifting, and plyometric training shows that different methods can improve strength, power, and speed in different ways (Morris et al., 2022).
So yes, train across the force-velocity spectrum.
But sometimes the language around this becomes far more complicated than the concept needs to be.
Sometimes an athlete needs to:
get stronger.
Sometimes they need to:
move faster.
Sometimes they need to:
sprint more.
Not every training quality needs a trademarked zone.
10. “NEUROLOGICAL ADAPTATIONS”
This is where strength and conditioning often disappears into fog.
The nervous system is obviously important.
Strength training produces neural adaptations.
Motor-unit recruitment matters.
Rate coding matters.
Coordination matters.
Skill matters.
But the phrase “neurological adaptation” is increasingly used to explain almost anything.
Athlete jumps higher?
Neurological.
Athlete feels better?
Neurological.
Exercise looks unusual?
Neurological stimulus.
Performance improves after a drill?
Nervous system switched on.
That is not enough.
If a coach claims a method:
“synchronizes the nervous system,”
“resets the nervous system,”
“balances the system,”
or produces a specific neural adaptation,
then that mechanism should be measured.
A performance change does not automatically prove the proposed neurological explanation.
This is where I think a lot of modern coaching jargon gets ahead of the science.
11. OSCILLATORY TRAINING
Rapid partial-range repetitions may be useful.
They may expose athletes to different joint positions.
They may create high contraction frequencies.
They may challenge coordination.
But there is very little high-quality research demonstrating that Triphasic oscillatory methods create unique performance adaptations.
This is a classic coaching progression:
Coach experiments.
Athlete improves.
Coach names the method.
Mechanism gets proposed.
Other coaches repeat the explanation.
Ten years later, everyone talks about the method as if the mechanism had been scientifically established.
That is not how evidence works.
Interesting tool?
Yes.
Established method?
Not really.
12. REFLEXIVE PERFORMANCE RESET — RPR
This one loses me.
RPR is promoted as a method that can “reset” breathing patterns, muscle function, movement patterns, and nervous-system behaviour.
That is an extraordinary claim.
Extraordinary claims need very good evidence.
Touch can certainly affect perception.
Breathing exercises can affect physiology.
Warm-ups can change performance.
Expectation effects are real.
Placebo effects are real.
Athletes can feel better after almost any ritual they believe helps them.
But none of that demonstrates a special neurological “reset.”
I cannot find a convincing independent peer-reviewed body of research demonstrating that pressing specific areas of the body through RPR reliably resets neurological dysfunction or restores reflexive muscle activation through the proposed mechanism.
That does not mean an athlete cannot feel better afterward.
It means: feeling better is not proof of the explanation.
Before I accept the word “reset,” show me what was physiologically broken, measure it, perform the intervention, and demonstrate that it has actually been reset.
Until then, I would leave the neurological language out of it.
13. BLOCK PERIODIZATION
Blocks are fine.
Sometimes emphasizing one quality for several weeks makes sense.
Training priorities change throughout the season.
Volume changes.
Intensity changes.
Sport demands change.
Fatigue changes.
That is normal programming.
But block periodization existing as a legitimate concept does not validate the exact Triphasic block sequence.
Again: evidence for the category is not evidence for the recipe.
14. TRIPHASIC TRAINING AS A SUPERIOR SYSTEM
This is ultimately the question that matters.
Does Triphasic Training outperform a well-designed conventional strength and conditioning program?
We do not currently have convincing evidence that it does.
Coaching experience matters.
Elite athlete success is not a controlled experiment.
Elite athletes also have:
great genetics,
excellent sport coaching,
medical support,
years of training,
huge training volumes,
nutrition support,
and a ridiculous number of other variables.
THE BIGGEST PROBLEMS
Research showing eccentric training works does not validate an eccentric block.
Research showing isometrics work does not validate an isometric block.
Research showing French Contrast works does not mean it is uniquely superior.
Research demonstrating neurological adaptation to strength training does not validate vague claims about nervous-system “resets” or “synchronization.”
This is the question coaches should keep asking:
To really validate Triphasic Training, I would want to see:
Triphasic programming
versus
well-designed conventional strength and power programming
with similar training volume, intensity, exercise exposure, and athlete level.
Then test:
strength,
jumping,
sprinting,
rate of force development,
reactive strength,
change of direction,
and ideally sport performance.
Until then, my view is fairly simple:
Triphasic Training contains a lot of good training wrapped inside a system whose scientific certainty exceeds the available evidence.
A coach can be excellent at producing results and still be wrong about the exact mechanism producing those results.
That distinction matters.
Maybe the athletes improve because the nervous system has been carefully progressed through three distinct phases.
Or maybe they improve because they:
got stronger,
sprinted,
jumped,
trained hard,
used appropriate overload,
and did it consistently under a very experienced coach.
Sometimes the simpler explanation is enough.
REFERENCES
Dietz, C., & Peterson, B. (2012). Triphasic training: A systematic approach to elite speed and explosive strength performance. Bye Dietz Sport Enterprise.
Liu, L., Niu, X., & Zhou, Z. (2024). Acute effects of different conditioning activities on the post-activation performance enhancement in athletes’ jumping and sprinting performances: A systematic review and meta-analysis. Applied Sciences, 14(20), 9301. https://doi.org/10.3390/app14209301
Morris, S. J., Oliver, J. L., Pedley, J. S., Haff, G. G., & Lloyd, R. S. (2022). Comparison of weightlifting, traditional resistance training and plyometrics on strength, power and speed: A systematic review with meta-analysis. Sports Medicine, 52, 1533–1554. https://doi.org/10.1007/s40279-021-01627-2
Oranchuk, D. J., Storey, A. G., Nelson, A. R., & Cronin, J. B. (2019). Isometric training and long-term adaptations: Effects of muscle length, intensity, and intent: A systematic review. Scandinavian Journal of Medicine & Science in Sports, 29(4), 484–503. https://doi.org/10.1111/sms.13375
Wilk, M., Zajac, A., & Tufano, J. J. (2021). The influence of movement tempo during resistance training on muscular strength and hypertrophy responses: A review. Sports Medicine, 51, 1629–1650. https://doi.org/10.1007/s40279-021-01465-2
Zhang, X., Weakley, J., Li, H., Marcos-Frutos, D., et al. (2026). Acute and chronic effects of accentuated eccentric loading vs. constant-load resistance training: A systematic review and meta-analysis. Sports Medicine, 56, 1749–1770. https://doi.org/10.1007/s40279-026-02422-7
Zhao, Z., Ma, Z., Wu, C., Zheng, X., Liu, T., Deng, N., & Zhou, K. (2025). The effects of French contrast training on lower limb athletic performance in healthy adults: A systematic review and meta-analysis. Frontiers in Physiology, 16, 1672353. https://doi.org/10.3389/fphys.2025.1672353
