I didn’t know changes in intramuscular fluid volume could influence force and velocity of contraction to the magnitude they do. I have been updating my Optimising Strength and Power course and found this article by Sleboda et al (2019) fascinating (https://lnkd.in/g25Faw_S). In short when you exercise, muscles can increase in volume by as much as 20% as fluid moves into the tissue, and small (5%) volume changes can result in > 10% increases in passive force.
These changes can happen during and after a workout and are thought to be due to dynamic fluid changes on muscle shape. Just another factor to consider when we observe acute changes in the force-velocity capability of muscle.