The phrase "gastrocnemius muscle" refers to a muscle located in the calf of the leg. It is responsible for helping us walk, jump, and stand on our toes. Full definition
They report that the partial squat produced greater medial gastrocnemius muscle activity compared to the parallel squat, despite a greater range of ankle motion during the parallel squat. (strengthandconditioningresearch.com)
Therefore, it appears that any differences in gastrocnemius muscle activity between the back and overhead squat at the same relative load, is likely due to the differences in the absolute load being lifted. (strengthandconditioningresearch.com)
This is likely due to superior medial gastrocnemius muscle activity during the concentric phase of the narrow width squat. (strengthandconditioningresearch.com)