Tighten Your Belt, Strengthen Your Mind
is an op-ed piece by Sandra Aamodt and Sam Wang in the New York Times.
Every time I read something like this it seems to light my brain on
fire. I recommend you read the article but the key thing I took out of
it is this: any mental process is a biological process and has the same
properties as most physiological processes of the body. What got my
brain going is the fact that there is a finite capacity to mental
processes and an adaptive quality to them.
Self-discipline or will-power, it turns out, is very much like muscle
strength, finite and adaptive. The article reports the finding that
when someone uses their will power to do something like quit smoking,
they are more likely to display a decrease in discipline in other areas –
they gain weight for example because they are not able to control their
eating. However, over time they are able to grow their level of
self-discipline and reach the point of being able to not smoke and not
over-eat – one adapts by investing effort and grows their finite
So what? Well, this knowledge is important for a couple of reason:
Given that people have a finite amount of will power, their chances
of success for adopting a new habit or eliminating a bad one greatly
increase if they do not try to do too much at once. If we take changing
body composition as an example, we know that you need to do two main
things to achieve a leaner body – exercise and eat well. You increase
the likelihood of being successful if you pick one of them to focus on
for a month and then start to focus on the other. If you focus on both
at the same time your limited will-power will be split between the two
increasing the chances that you fall off the wagon on one or both of
them. You are better to make small steps and slowly build up the number
of good habits.
Also, people cannot use the excuse that they “just don’t have the
will power” to stick to something. True, they may not have it right now
but if they invest the time and effort they WILL end up developing it
and it will allow them to stick to it.
Very often people will ask me what the best rep range is for
building mass. It’s a simple enough question but like everything else
with the body, the answer isn’t as simple as saying “6-9″. From my
experience it has more to do with training age, time under tension, and
As one trains, they get better at recruiting motor units and are therefore able to achieve the same workout with fewer reps. E.g. assuming the average newbie is able to recruit 40% of their motor units. As they perform reps, fatigue will set in and in order to continue the set, they will need to recruit different motor units. At some point they will fatigue all available units and the set will have to end. Assuming a 5% fatigue rate of the total units per rep, they will be able to do 12 reps before they fail.
Someone who has a higher training age will be able to recruit more
units per rep. They will also have more muscular endurance which will
delay fatigue. Assuming they are able to recruit 80% of the available
motor units per rep and that 3% of them fatigue per rep, they will be
able to do 7 reps before they fail.
The end result is that failure occurs after 7 reps for the trained
athlete and 12 reps for the new athlete. Both achieve the same
physiological state of failure; it just takes fewer reps for the trained
athlete to get there BUT they’ll be using a much larger weight.
Time Under Tension:
Regardless of most other factors, the length of time it takes to complete a rep will impact the amount of work that one is performing and it will impact the amount of motor recruitment. 6 reps with 505 tempo will recruit more fibers than 6 reps of 211 tempo. When someone asks a question which is better for growth, 4-6 rep ranges or 12-15 rep ranges but doesn’t mention tempo the question is impossible to answer. 12 reps at 101 tempo = 24 seconds TUT while 6 reps at 505 tempo = 60 seconds TUT. You’ll get better size gains with 60 seconds than you will with 24 seconds, but you’ll be able to handle more weight for sets lasting 24 seconds vs. those lasting 60 seconds.
Some of the motor units *may* not be recruited at slow speeds while others will not be recruited when moving at a fast speed. IF you do not recruit a motor unit the muscle fibers that these motor units control will not grow. There is also a growing body of research that indicated that the growth potential is not the same for all fiber types / motor unit types – fast twitch appear to have the potential to grow more than slow twitch.
Putting It All Together:
Keeping TUT between 45 and 75 seconds and varying rep speed is key once training age reaches a certain point or, more accurately, once you gain a certain amount of control over your motor units. Remember too that the body adapts quickly to EVERY action that it has to perform so variety is key.