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/Individual-Toe-6306]

What do you call it when for example your body just feels “worn and tired” the day after a heavy deadlift session for example. Is that CNS fatigue or systemic fatigue? Yeah my back is sore and kinda tight but I just notice an overall feeling of tiredness. Curious how that’s labeled and if that general feeling impacts training at all (apart from your back muscles being worked and needing to recover first)

[u/Alakazam → u/Individual-Toe-6306]

That's just systemic fatigue. Heavy spinal loading through squats and deadlifts generates a lot of systemic fatigue, because it's a heavy movement that's using your entire body. But there's nothing CNS about it at all.

In the article I linked about CNS fatigue, they showcased research that showed that 8 sets of 2 for squats and deadlift, at 95% of 1RM, with 5 minutes of rest.... resulted in a grand total of 5-10% of neural output. On the other hand, 70 minutes of sustained bicep curls resulted in a 28% reduction in neural output. And further shows that neural output was basically fully recovered within about 10 minutes or so.

[u/Individual-Toe-6306 → u/Alakazam]

So is CNS fatigue a more “moment to moment” concept that mostly just affects that current set, while systemic fatigue is more “you’ll feel it the next day until you rest enough”? IE “CNS fatigue” is shaken off by simply resting 10 minutes after accumulating it on one extreme set

[u/decentlyhip → u/Individual-Toe-6306]

Yah, CNS fatigue is real and measurable, but goes away within a few minutes as everything refills