Do the effects of Morning Neuromuscular Deficit make morning training inferior to afternoon training?

Question

It seems to be widely accepted in fitness folklore that people are typically stronger in the afternoons than they are in the early mornings. This phenomenon, called Morning Neuromuscular Deficit is actually well documented in scientific literature. The abstract of one such study, "Morphological, molecular and hormonal adaptations to early morning versus afternoon resistance training" states:

It has been clearly established that maximal force and power is lower in the morning compared to noon or afternoon hours. This morning neuromuscular deficit can be diminished by regularly training in the morning hours. However, there is limited and contradictory information upon hypertrophic adaptations to time-of-day-specific resistance training.

I have been lifting since October 2020, and have consistently found that I am significantly stronger in the afternoons than in the mornings. I usually lift at 06:00 prior to work, except, occasionally I will do an afternoon workout.

I deadlifted last Sunday afternoon and this morning (Thursday, four days later). Sunday, after warming up, I was able to hit five singles at 315 on about 3 minutes rest. This morning, after a similar warmup, I could not get 315 off the ground. This is a pretty consistent pattern for me, on other exercises as well. I am always able to lift heavier weights at the same perceived exertion in the afternoon.

Here's the question. Does this deficit in load make morning training inferior for me? Obviously if I did the same workout with the same weight in the morning or afternoon, it would make little difference. But my thinking is that lifting more weight at the same perceived exertion would be better for muscular adaptation. I would expect to see more improvement from five singles at 315 than five singles at 275.

Is the afternoon a better time for me to workout, for the reason that I can lift heavier loads, thereby doing more work?

Update, August 2022: The quoted abstract claims that regular morning training can attenuate the morning strength deficit, and I have found that to be correct. I've been consistently training in the early morning since first posting this question, and where I used to see better performance in the afternoons and evening, the difference has been eliminated.

Answer 1

While perceived exertion can be a useful tool, it shouldn’t be overemphasized. If it was such a potent force in producing strength and hypertrophy adaptations, then we would see widespread abuse of muscle relaxer drugs in the fitness industry. But we don’t because the only thing they do is make the perceived exertion of every movement much more difficult.

Now it’s certainly the case that muscle relaxer drugs are taking this idea of perceived exertion to an extreme, but that’s to better illustrate the limitations of perceived exertion as a tool. What about a less extreme example like morning training? If perceived exertion is off the table, I see no physiological justification to suggest that subpar training could produce an equally effective training stimulus.

Practically however, is it still possible to improve? I don’t see why it wouldn’t be. As you already surmised, you would certainly benefit more from doing the heavier set, but that hardly suggests that you couldn’t benefit from the slightly lighter set. Yes, morning training is oftentimes inferior to later training. However, any sufficiently hard training will produce a stimulus for adaptation.

Ways to improve morning training to be more equal to later training would include; warming up more, being more alert, not being fasted (but also not digesting too much), being more hydrated, and simply doing it more often might help your body to adjust.