From the diagrams it seems only the maximal level of exercise strain is significantly affecting sleep.
> Exercise strain was quantified using summated-heart-rate-zones scores (SHRZS).
Aerobic exercises at maximal level are not every day thing and by themselves do require up to 72 hours of recovery. Even for elite athletes it would be maximum once or trice per week, depending on the mesocycle.
> The present study had limitations that should be considered. [...] The summated-heart-rate-zones score (SHRZS) method for quantifying exercise strain may underestimate the relative metabolic strain of strength training that involves very brief durations of high-effort movements. Future research could examine the effects of different types of evening strength training (e.g., Olympic lifting).
For weightlifting volume (number of sets) and intensity (weight attempted) of the exercise combined with maximum HR would be a better measure.
> We were unable to control for potential confounds known to impact sleep, such as bright light exposure.
In my experience, at the end of preparatory phase (at the maximum stress) any light leaking into bedroom will make it difficult to fall asleep.
> Exercise strain was quantified using summated-heart-rate-zones scores (SHRZS).
Aerobic exercises at maximal level are not every day thing and by themselves do require up to 72 hours of recovery. Even for elite athletes it would be maximum once or trice per week, depending on the mesocycle.
> The present study had limitations that should be considered. [...] The summated-heart-rate-zones score (SHRZS) method for quantifying exercise strain may underestimate the relative metabolic strain of strength training that involves very brief durations of high-effort movements. Future research could examine the effects of different types of evening strength training (e.g., Olympic lifting).
For weightlifting volume (number of sets) and intensity (weight attempted) of the exercise combined with maximum HR would be a better measure.
> We were unable to control for potential confounds known to impact sleep, such as bright light exposure.
In my experience, at the end of preparatory phase (at the maximum stress) any light leaking into bedroom will make it difficult to fall asleep.