Exercise Selection for Regional Growth: Lengthened Positions and Targeted Choices

Overview

A muscle does not grow evenly, and muscles that cross two joints can be trained at very different lengths depending on body position. This lecture covers controlled trials showing that exercise choice and body position change how much, and where, a muscle grows.

Triceps: overhead vs arms-down extensions

The triceps long head crosses the shoulder, so it is more stretched with the arm overhead. Twenty-one adults trained one arm with overhead cable extensions and the other with the arm at the side, for 12 weeks.^[1]

• Long head: +28.5% overhead vs +19.6% neutral.
• Lateral and medial heads: +14.6% vs +10.5%.
• Whole triceps: +19.9% vs +13.9%, despite lighter absolute loads in the overhead position.
• Authors' recommendation: do cable extensions overhead rather than with the arm at the side.

Glutes: hip thrust vs back squat

Untrained participants trained either hip thrusts or back squats for 9 weeks, with sets equated.^[2]

• Glutes: similar growth, with estimates modestly favoring the hip thrust.
• Squat-only gains: the squat group grew the quadriceps and adductors more.
• Strength: each group gained more on its own lift, and both transferred similarly to the deadlift.