When force is applied at a high rate of tension, in most systems, there will be eventual failure or fatigue that accumulates. Humans are set up in a similar way, primarily for protective reasons. With all things being equal, the reason for someone failing on the concentric portion of an absolute strength lift on the third rep is different than someone failing on the ninth rep.
 
Allow your brain to wander a little now. Can you see how the reasoning about why someone fails on the 23rd rep (in the same context as above) is a little…grey? Like it or not, humans participating in the new version of the intense fitness model have created a lot of interesting observations around this grey area, one being how some can and some cannot make some resistance almost seem, shall we dare to say, aerobic. As new methods of fitness unfold, coaches and athletes need to start rethinking the area under the curve for resistance and fatigue. Otherwise, we might miss something important.
 
Play
 
My play and experimentation with all things strength and conditioning has taken me on many travels. I have been fortunate enough to learn from a lot of the greats in the resistance, power, and endurance world and to try to make sense of what I have learned on my own. I have been trying to find these truths while working with thousands since 1994, with some failures, some successes, and a lot learned.
 
In these applied settings, one area I began to try to understand on a deeper level was how exactly some folks made resistance seem aerobic in nature. I knew based on models of biology how things should operate, based on the organism, stress imposed, and adaptation to that stress. I applied these biological ideas within a mechanical mind in my university days, but still needed some answers to my questions. My curiosity was based on observations such as WHY in N=2 scenarios, with all things being equal, people respond differently under the 1RM curve when tension is applied. That is, asking two similar folks with the same gender, training age, height, weight, etc. to perform as many reps as possible of 85% of their 1RM back squat at controlled tempos, and other simple testing scenarios, yielded massive variance in scores.
 
When I started training teams, and groups of teams, the data that unfolded made it even more apparent that folks run differently under the hood under this 1RM. An example would be a team of competent female row crew. Scores would vary from 6 to 19 reps at 85%. When I applied these tests to the fitness world population, just to see how that group responded, I saw even more variation. It’s not uncommon to see some perform 3 reps and some perform 22 reps at 85%, mainly due to training age.
 
Then in the sport of fitness, new athletes were making thrusters and pull ups at high speeds and rates look aerobic--finishing the session minutes faster than others and speaking 15 seconds later about how it went. What was once thought to be painful and intense was starting to be seen as a separator in terms of good to great. I wanted to know why.
 
Applied science
 
This brought me down the road of trying to apply what I knew to be true with resistance and why people would get tired, along with understanding of how people make things aerobic and sustainable, and seeing how the two worlds met. They meet in the “middle zone”--the area under the curve where over time there are rapid changes as continual tension is applied in resistance.
 
Think of a simple, controlled leg press testing scenario where someone starts to fail at a certain load at 5 reps, then at another load at 15 reps, then at another load at 37 reps… In scientific principles, I thought I had an answer based on fuels used, contraction ability, and neural control. After all, we kind of know that we are doing resistance at its height when we lift something for eight seconds and on the ninth second there is failure. (Call it alactic work). And we know we are doing endurance work when we hold the same pace on something for 25 minutes--and possibly longer than that. (Call that oxidative work.) And we are learning more about fatigue in the middle “grey" zone due to the advent and practice of intense fitness and the sport of fitness. (Call this lactic work, possibly.)
 
Dose response
 
On the track, in the gym, in the pool, on the court, it is very challenging for the coach to apply science to work and rest scenarios and dose response—to determine the effect of the training stimulus. This is why coaches are coaches: they want to create that eye for when things are right or wrong, good or bad, moving forward or moving backward. The one way we have investigated the aforementioned strength, middle zone, and endurance work is simply seeing the dose response of the person when performing the work, as well as how they recover from it in repeated stress situations. And here is the funny thing, back to the original context of weights becoming aerobic: in the world of intense fitness, some folks make that middle zone turn into aerobic with resistance.
 
Take a simple example of the leg press again. Figure out everyone’s 1RM on the leg press. Then take a similar percentage under the 1RM and make everyone do the reps at the same tempo - preferably assuming (based on loads you chose) that everyone will finish anywhere from 40 sec to 3+ minutes. There are three possible different responses people give to this effort.
 
1. “I just could not simply contract my legs anymore at 45 seconds, and felt fine right after.”
 
2. “My legs were burning so much and my breath rate went high and I could not sustain the pain at 90 seconds”
 
3. “At around the 3-minute mark, my quads were beginning to start to cramp so I called it--but it was not that painful.”
 
The third response is what we are calling a dose response of alactic/aerobic work.
 
Even though all participants were the same and used the same percentage under the 1RM, the third response makes you wonder why they can do this, why might it be important, and how many folks are feeling this way and getting this effect.
 
Many factors
 
There are many factors that make people sustain longer than others under certain sub maximal resistance and the reason is not only their absolute strength

Just in case you’re thinking that all one has to do is improve their absolute score in a certain area and voila, they have better sustainable resistance as they get stronger, be aware that this is a very lower order view of how humans respond to different stimuli. Factors include gender, training age, biological age, aerobic ability, personal essence, local muscle fiber type distribution, and DNA, to name a few. One can only imagine the immense study required on each of these in order to sum up someone’s “ability under the curve.” I wish it was only the case for absolute strength, that we could just focus on this area and all things would work out, but in reality, it’s a lot more complex than that.
 
Effects and reasoning 
 
Training to improve this alactic/aerobic area can hamper strength speed co-ordination, high turnover threshold work, aerobic capacity and absolute strength, etc.—but that doesn’t mean it will. This type of training has an effect on other areas of work as well. This is not just local muscle endurance work.
 
The reasoning behind applying this kind of work can be for folks who need this actual characteristic as part of their function, for sport or life. There are definitely some areas of sport and life where this training does not apply, but the sport of fitness is a fascinating area where it does apply.
 
Why make resistance unsustainable? Why would you want to get tired on a task of various things that were put there for time? Against someone else? It actually makes no sense to train into the “grey” area of fatigue all the time. Why not just make it aerobic? It’s much more simple. It flies in the face of intensity, though, because there is so much attachment to the suffering. Just know that one can still make a workout challenging, create metabolic adaptations, and get “intensity” from it from the proposed alactic/aerobic work.
 
A simple example of part of a session could look like this (and again--this could have a drastically different effect for you or your clients).
 
For time:

8 TGU - alternating arms per rep - 2 pood
30 pistols 
HS walk 3 x 10 m unbroken
legless L sit rope climb x 5 - 20’
20 burpee box jump over - 24”
 
This particular workout obviously has pros and cons to it, which is why it has to be tailored to the individual. If you see it as a mix of anything without reason, you are right in one case: it is a mix of anything. The reasoning behind it is what differentiates coaches from fitness instructors. The goal of such a prescription is to apply these principles, and as such the learning of possibly performing this style of training:

• The work remains alactic/aerobic throughout - no redlining.
• The work does not hamper current trends in absolute strength or aerobic capacity - as measured weekly or daily.
• The work does challenge some skills to be made sustainable under the alactic/aerobic curve.
• The work does not create a lactic bath of "hands on knees" and suffering for 15 minutes.
• The recovery from the workout should take two to three minutes before new skills and training can begin.

When you create this effect, the work done in most cases is this area of sustainable resistance. The variation does create little rest periods between movements, and the lack of a high amount of faster eccentric contractors does help it become sustainable.
 
Creativity
 
It is important to understand that one cannot get attached to the style or the purpose of the workout but instead fall in love with the dose response. This will open your eyes to the possibility of training variation, but getting after things from a different source and way. Someone can get the same effect of both of the following workouts - and the same improvements:
 
Option 1:

A. snatch (technique work)
B. snatch (sub-maximal work)
C. squat (intensity - mechanics based)
D. single-leg supplementary work
E. muscular endurance work—upper body pushing
E. core work
 
Option 2:

A. Sotts press - find a 3RM in 8 min
B. snatch-build to 90% x 1 in 12 min - EMOM
C. squat (intensity - mechanics based)
D. 4 rounds for time sustainable:
10 tough KB front rack walking lunges - increase weight each round
10 strict HSPU
10 ring push-ups
10 strict dip
15 dynamic toes to bar
 
Reminders:

This does not mean this is the method everyone should apply; it’s a case about what is actually happening when people get the same results from the same program.

This program should have no mechanical fatigue in place - no sloppy reps, and constant movement with solid breathing control.

The work challenges the skills to be applied without straining them to result in poor adaptation. It is not suffering, and you should recover well within minutes after its performance, for the purpose of training the alactic/aerobic work
 
This does NOT mean that everything goes out the window now for the specific resistance training reps and sets under controlled work and rest scenarios. It should, however, allow you to see how two ways (of 20+ possible ways) can get the same responses. Sometimes the bias we have about what is supposed to be training clouds our view of what can be or is happening when some individuals train this way—and still make improvements in absolute strength as well as aerobic capacity, all without harm.
 
Where my mind again goes is how someone can make this sustainable? By sustainable, I mean that they are doing four rounds with a little effort applied, pacing accordingly, and then finishing and thinking about what’s next. If you finish this, or try it, and have shoulder pain, get gassed quickly, fail on your weight chose election - then that is just you, it’s not the workout. It means you need some lessons on mechanics, pacing, and doing 1000 quality reps instead of a million bad ones. This is also why it needs to be applied with the ideas I’ve presented on the principles of dose response in mind.
 
Today
 
My day to day now revolves around teaching clients and coaches these principles, as my belief is that all things can be applied for the right person at the right time if they make sense. Allowing ourselves to stretch the mind into possibilities that go against our beliefs is the only place where we can grow. In the case presented, I think it’s time to start rethinking fatigue under resistance and the reasoning behind this fatigue. I think what we will find if we continue to look at it are some missing links to improved performance.