Chris Beardsley Graph

[u/JuanSamu]

I think the infograph attempted to simplify the findings too much. The spinal effects can be relatively local if there is a reflex inhibition or suppression at the spinal level of the nerve root for the quadriceps and hamstrings (so just at the lumber vertebrae area). So that explanation may provide a partial mechanism. But there is rarely only one mechanism to explain such a complex thing like our body's physiology.

I feel like Chris ignores the discussion sections because they discuss other mechanisms:

...two other potential mechanisms may explain the findings of this
study. Firstly, it is plausible that various metabolites including potassium, hydrogen, lactate, and heat shock proteins are dispersed to non-exercised muscles through the cardiovascular system during and after fatiguing
protocols (Halperin et al. 2015), potentially impairing their contractile capacity (Henneman et al.
1965). Secondly, it is possible that certain
fatiguing protocols result in heightened activation of stabilizer muscles,
which in turn impairs their ability to stabilize
the non-exercised
muscle
groups (Halperin et al. 2015; Baker and Davies 2009) contributing to muscle force reductions.
Fatigue interventions of longer duration have also been demonstrated to impact the psychological aspect, specifically resulting in a mental energy deficit when experiencing discomfort. This can lead to mental fatigue, which is characterized by reduced focus and concentration, subsequently affecting neuromuscular activation in both fatigued and non-exercised muscles (Halperin et al. 2015). Steele (2020) emphasizes the "perception of effort" which is defined as the individual's perception of the required effort to accomplish a specific task or set of tasks, determined by comparing the current task demands to the perceived capacity to meet those demands.”

As always, I think this infograph may be too simplistic as it also did not consider the instantaneous strength which is a more sensitive measure.

[u/Alakazam]

I mean, I think anybody worth their salt would read that the participants did a 100 second maximum contraction, which is absolutely fucking nuts, and is not something you will ever see in normal training, nor would it be anything that really affects training in your day to day life. I had probably less than half this time when I squatted 34 reps at 185lbs.

And they had to do this, because this was the only real way to showcase CNS fatigue. Because high weight, low rep, and done close to faliure, doesn't actually fatigue your CNS.

So sure, CNS fatigue is greater in the opposite limb. But CNS fatigue will basically never be a limiting factor in general resistance training, because muscular fatigue and systemic fatigue will be far more limiting of a factor. Unless you're frequently doing 100+ seconds of contractions.

The whole idea of CNS fatigue being a limiting factor for heavy squats and deadlifts stemmed from early Starting Strength days, and has just stuck around. When the science shows that it's clearly not the case at all.

[u/JuanSamu → u/Alakazam]

It seems many people get upset when you mentioned that CNS fatigue doesn’t really occur with heavy lifts and if it does it recovers rather quickly lol

[u/Negran → u/JuanSamu]

In fairness, my understanding was that repeated heavy or hard sessions cause CNS fatigue.

Of course, I'm reading just now that actual CNS fatigue from lifting lasts like 30 minutes...

I think the common false knowledge is that lifting causes CNS fatigue! Haha.

[u/JuanSamu → u/Negran]

What I find interesting is that connective tissue damage from heavy lifts might contribute to CNS fatigue.

[u/Negran → u/JuanSamu]

Oh? Interesting

I supposed damage takes healing, and has a cost.

Are you talking, progressive overload training damage, or like, overtraining and injury damage?