📚 Shoulder External Rotation at 0° vs. 90° @MuscleandMotion

Uploaded July 2026 | Updated September 2026, 2 weeks ago

A study by Kurokawa et al. (2014) revealed how muscle engagement changes with arm position during shoulder external rotation.

🔹 At 0° abduction: The infraspinatus does most of the work, powering the movement when your arm stays close to your body.

🔹 At 90° abduction: The teres minor takes over, showing peak activation when your arm is raised to the side. 💪

Understanding these differences helps you train smarter, enhance shoulder stability, and boost performance.

📲 Want to master shoulder training and understand every movement in 3D?
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📚 Shoulder External Rotation at 0° vs. 90°

$FRACTIONAL SETS 🤯 Are you actually counting your sets correctly? You log your chest sets during the bench press, but what about your triceps? A new meta-analysis by Remmert et al. highlights that during every compound lift, such as the bench press, shoulder press, or dips, the triceps play a meaningful role. They are not the primary movers, yet they still contribute enough to influence your total training volume. In other words, you might be training your triceps without even noticing. This is where the concept of Fractional Sets becomes important, as described in the paper: 👉 Direct set = an exercise that directly targets the muscle 👉 Fractional set = indirect work from a compound lift (approximately half a set) This matters because counting both direct and indirect work helps you reach the weekly training volume that actually drives results. What the researchers recommend: 💪Aim for 8-12 fractional sets per session to maximize hypertrophy, as gains tend to level off around 11 fractional sets. This doesn’t mean all sets must be fractional; combining direct and fractional work also works. For example, 5 direct sets + 6 fractional sets (equal to 3 full sets) give you 8 effective sets. ⚡For strength, about two direct sets per session appear sufficient before benefits begin to diminish. 🎯Match the exercise to the goal, since muscles respond differently to direct vs. indirect work. Start programming your training with confidence using Muscle and Motion Strength Training. Check out the Muscle and Motion STRENGTH TRAINING APP link in bio! #muscleandmotion #anatomy #strengthtraining #personaltrainer$

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