Muscle versus Neural “strength.”
People with bigger muscles are not necessarily “stronger” because strength is more than muscle mass.
For example, what if I asked you to [do a movement that requires “strength” that is unfamiliar]… does it feel like your body totally tenses up? With some practice, your body will feel less tense and the movement will feel less “effortfull.” You are not necessarily increasing muscle mass as you train this movement, you might just be training muscle recruitment.
For example, “cramps” during loaded movement (try hip flexor raises while sitting) are often a result of the “omg muscle ACTIVATE” signals that lead to co-contraction of more muscles than needed. With practice, less muscles get recruited for the movement and they can activate in a graded manner rather than “all-or-none.”
Del Vecchio, A., Casolo, A., Negro, F., Scorcelletti, M., Bazzucchi, I., Enoka, R., Felici, F., & Farina, D. (2019). The increase in muscle force after 4 weeks of strength training is mediated by adaptations in motor unit recruitment and rate coding. The Journal of physiology, 597(7), 1873–1887.
Suchomel TJ, Wagle JP, Douglas J, Taber CB, Harden M, Haff GG, Stone MH. Implementing Eccentric Resistance Training—Part 1: A Brief Review of Existing Methods. Journal of Functional Morphology and Kinesiology. 2019; 4(2):38.
HEDAYATPOUR, NOSRATOLLAH; FALLA, DEBORAH; ARENDT-NIELSEN, LARS; FARINA, DARIO. Sensory and Electromyographic Mapping during Delayed-Onset Muscle Soreness. Medicine & Science in Sports & Exercise 40(2):p 326-334, February 2008.
[Aagaard, Per. Training-Induced Changes in Neural Function. Exercise and Sport Sciences Reviews 31(2):p 61-67, April 2003.]