Pushing the weight up works your shoulder and arm muscles harder than lowering it down, no matter which press variation you do.
Claim Context
In competitive male bodybuilders, muscle excitation is significantly greater during the ascending (concentric) phase than the descending (eccentric) phase of all overhead press variations for all muscles measured, with effect sizes ranging from 2.67 to 12.38, indicating the concentric phase imposes greater neuromuscular demand under the tested conditions.
“The nRMS was greater during the ascending vs. descending phase in all exercises (ES ranging from 4.83 to 12.38).”
Evidence from Studies
No evidence studies found yet.
What Would Prove This
Per GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this claim, ordered from strongest to weakest.
Causal effect of emphasizing concentric vs eccentric phases on muscle growth.
A 10-week RCT with 80 trained men randomized to concentric-emphasis or eccentric-emphasis overhead press (3x/week, 3 sets of 8 reps), measuring deltoid hypertrophy via MRI, strength, and EMG, with time under tension matched.
Overall evidence on concentric vs eccentric muscle activation and growth in resistance training.
A meta-analysis of all RCTs comparing concentric vs eccentric emphasis in upper-body exercises, pooling EMG, hypertrophy, and strength data.
Association between training focus and muscle development.
A 1-year cohort of 150 lifters tracking concentric vs eccentric emphasis and deltoid growth via ultrasound.
Current differences in muscle size based on training emphasis.
A cross-sectional study of 100 male bodybuilders comparing deltoid thickness and self-reported concentric vs eccentric focus.
Individual responses to phase-specific training.
A case series of 5 athletes who adopted eccentric-only pressing, documenting changes in muscle size and strength.