A longstanding belief in strength training holds that the eccentric phase—the lowering portion of a lift—is critical for muscle development.
While eccentric movements are indeed influential in promoting muscle growth, a new comprehensive analysis reveals that within typical time frames of 1 to 6 seconds, the precise speed of the eccentric phase has little impact on muscle size.
Instead, maintaining consistent training volume and effort appears to be far more crucial, regardless of whether the weight is lowered quickly or slowly.
The Study
Published in the Journal of Sports Sciences, this meta-analysis aimed to clarify whether the tempo of the eccentric phase influences gains in muscle size, strength, or jump performance.
Previous studies yielded inconsistent results, often confounded by changes in multiple lifting variables simultaneously, making it difficult to isolate the specific effect of eccentric tempo.
Research Approach
The authors examined five major databases, screening thousands of studies to identify nine that specifically compared short (1–2 seconds) versus long (3–6 seconds) eccentric durations while controlling for other aspects of the lift.
The analysis incorporated data from 166 participants—about half experienced lifters—over training periods ranging from four to twelve weeks. Each study met criteria including a minimum four-week duration, healthy participants, and matched training volume or effort across groups.
Key Findings
Muscle Growth (Hypertrophy): No significant difference in muscle size was observed between faster and slower eccentric phases; both tempos resulted in similar hypertrophy outcomes.
Strength Gains: Results were less definitive, but in trained individuals or when volume was equated, longer eccentric durations showed comparable or slightly greater strength improvements.
Jump Performance: Shorter eccentric speeds consistently yielded superior enhancements in countermovement jump height.
Implications and Conclusions
The study suggests that eccentric tempo is not a major factor in muscle hypertrophy but may influence other fitness parameters, warranting further research across diverse populations and training protocols.
Importantly, controlling the eccentric phase remains essential—merely slowing the lowering phase without control may reduce muscle tension and limit gains. Supporting this, a review in The Journal of Functional Morphology and Kinesiology noted that hypertrophy can be achieved with total rep durations between 2 and 8 seconds, finding no clear advantage to extending eccentric or concentric phases beyond this range.
Regarding strength, longer eccentrics can enhance muscle work, particularly improving strength in weaker joint angles, such as the bottom position of pull-ups or push-ups, thereby transferring to stronger full-range repetitions.
Bottom Line: While it’s vital to control the eccentric phase, deliberating between 2- and 6-second eccentric durations is unlikely to significantly affect muscle growth outcomes.
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