I'm Steve — MiniWorkoutDad!
Why We Don’t Add Reps To Our “Silly Workout”
Why do we do holds instead of reps? Why for 15 seconds? What’s the science behind our workout? Read on to find out…
So, why does our workout use holds and not reps?
Scrolling across a quote from veteran bodybuilder Mike Mentzer was the ‘Eureka!’ moment that created our workout.
As a busy father aged 51, I knew that, if I was going to start working out again after 4.5 years, I needed a workout that’s:
- Quick/ efficient, because time is precious and limited
- Sympathetic to an ageing body
- Effective at building fitness AND muscle
Enter long deceased bodybuilder and trainer Mike Mentzer
Sadly Mike Mentzer died long before Instagram happened. But, somebody replaying Mike on Instagram, saying “I have come to discover that LIFTING WEIGHTS is a WASTE of TIME“, was exactly the lead I needed to look into isometrics. The fit was obvious:
- Not doing many repetitive movements was surely kinder on my older body? I could feel the burning bursas and tender tendons just thinking about all those reps and sets I used to do.
- The efficiency of holding contractions at maximum effort, instead of moving through very little effort, to maximum and back, could achieve much higher intensity in less time.
Higher intensity has another benefit: no need to do extra cardio on top! You’ll know you can get seriously out of breath doing the workout. It pushes your fitness as well as strength.
One final twist made the workout what it is: choosing a functional training approach!
Whereas most gym machines and routines try to isolate individual muscles, instead you work multiple muscles in every lift or hold. That saves even more time.
But, what’s happening during those isometrics holds?
And, why do we hold them for 15 seconds?
Well, first off, there’s no such thing as an isometric hold, because isometric means “muscular contraction that does not produce shortening of the muscle”. When, actually, they do.
Yes, muscles contract during isometric holds through three different mechanisms:
- Tendon creep – the tendon elongates, so the muscle has to contract to maintain position[1]
- Constant oscillations of shortening and lengthening of the muscle[2]
- Mechanical instability, because we are simply not that good at holding things steady![2]
A study found that during a yielding isometric, the longest isometric plateau (where measurement flattened and held steady) amounted to 31.6% of the overall duration time of isometric measuring.
This isometric builds muscle for carrying!
My strong “back chain” muscles, 7 months after doing The Weekly 75 workouts.
So, your muscles and nervous system are a hive of activity during your holds, as constant adjustments are made. In fact, there’s evidence that isometrics generate higher muscle activation (over 95% versus less than 90%) when compared with concentric/ eccentric movements[3].
But, why 15 seconds?
“What made you choose both an arbitrary time under load and nine circuits?”
When Lee asked this in a comment about a week ago, I could see why 15 and 9 may seem “arbitrary”. But, they are based upon science, logic and practicality!
Here’s the main finding I used (IST = Isometric Strength Training):
“To increase muscle hypertrophy, IST should be performed at 70-75% of maximum voluntary contraction (MVC) with sustained contraction of 3-30 s per repetition, and total contraction duration of >80-150s per session for >36 sessions.”
Danny Lum, Tiago M Barbosa, International Journal of Sports Medicine 2019 [4]
So, let’s unpack that finding:
- Our 15 seconds is almost midway in the 3 – 30 second sustained contraction band, while being an easy memorable number.
- Doing 9 cycles, gives 9 x 15 = 135 seconds total contraction duration. 6 cycles would exceed the minimum. But, 3 extra gives us more cardio time and is within the recommendation.
- 36 sessions at 3 sessions a week is why you should give it 3 months. I don’t recommend more than 3 workouts per week, because recovery is as important as the stimuli.
- 70-75% of MVC is why I encourage you to embrace intensity by working at a heavier weight.
Overall, 15 and 9 are good compromises. Longer holds could get really tedious. More than 9 rounds would be impossible in 25mins – it’s already a stretch objective!
You get the most from the last second, so stop cheating…
That’s why I follow my workout video, every workout!
I hope that knowing the “why” behind the workout encourages you to work even harder in your 75mins a week. As you can see, 3 months of consistency should be your goal, before making judgements. That chimes with when I really started to get excited about my progress. And, I hope you will reach that point too!
Steve — MiniWorkoutDad
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References
1 – Behaviour of the Human Gastrocnemius Muscle Architecture During Submaximal Isometric Fatigue. Lida Mademli, Adamantios Arampatzis – European Journal of Applied Physiology, August 2005
2 – Are there two forms of isometric muscle action? Results of the experimental study support a distinction between a holding and a pushing isometric muscle function. Laura V. Schaefer and Frank N. Bittmann – BMC Sports Science, Medicine and Rehabilitation, May 2017
3 – Activation of human quadriceps femoris during isometric, concentric, and eccentric contractions. N Babault, M Pousson, Y Ballay, J Van Hoecke – Journal of Applied Physiology – Dec 2001
4 – Brief Review: Effects of Isometric Strength Training on Strength and Dynamic Performance. Danny Lum, Tiago M Barbosa – International Journal of Sports Medicine, May 2019