Rep Speed for Muscle Growth: Did I Overhype Slow Reps?

Quick Overview

Dr. Mike Israel concludes he was not wrong about rep speed for muscle growth; while extremely slow eccentrics (like 5-6 seconds) are equivalent to 1-2 second eccentrics for hypertrophy, the constant cueing of 'slow' led to the misconception that he advocated for excessively slow reps, which he clarifies is not the overall recommendation, especially for advanced trainees who can safely use fast eccentrics.

Key Points: Dr. Mike Israel admits he was wrong in assuming that his emphasis on controlled eccentrics would not be misinterpreted as advocating for "super slow training" (00:05, 00:50). Scientific literature suggests that eccentric phase times between 1 second and 6 seconds are roughly equivalent for muscle growth (07:59). The primary reason for cueing slower eccentrics at the bottom of the rep (especially for pro bodybuilders/high-level athletes) is safety, as their large muscle mass can outpace tendon strength, increasing injury risk (03:44, 03:50). Slowing the eccentric phase allows for better mind-muscle connection, ensuring the target muscle is actively resisting the weight rather than just succumbing to gravity (05:15, 05:33). If the eccentric phase is quick (e.g., 0.5 seconds), technique cues like 'knees out' are processed too late to be useful during that specific repetition (05:54). If confidence, technique, and muscle connection are rock-solid, athletes can safely use fast eccentrics (1-2 seconds or rapid) on the concentric phase without sacrificing hypertrophy (09:38, 10:41). Intentionally slow concentrics are viewed as sucking the fun out of training, though slower eccentrics for variation are perfectly fine for a few months at a time (11:13, 09:09).

Context: Dr. Mike Israel addresses a common misinterpretation of his training advice, specifically regarding rep speed, where he was perceived as promoting 'super slow training' for muscle growth. He clarifies that this misunderstanding arose because he consistently cued slower eccentrics, particularly to his advanced clientele like IFBB Pro Jared Feather (00:00, 01:41), to enhance muscle connection and ensure safety due to their large muscle mass and the risk of tendon injuries (03:44).