# Rep Speed for Muscle Growth: Did I Overhype Slow Reps? Source: https://www.youtube.com/watch?v=reiB9uQ6O4E Recap page: https://rapidrecap.app/video/reiB9uQ6O4E Generated: 2025-12-23T17:40:39.991+00:00 --- ## 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). ![Screenshot at 00:47: Dr. Mike Israel introduces the central question of the video: 'WAS I WRONG ABOUT REP SPEED FOR MUSCLE GROWTH?' while setting up the context that his past emphasis on slow eccentrics may have been misinterpreted.](https://ss.rapidrecap.app/screens/reiB9uQ6O4E/00-00-47.jpg) **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). ## Detailed Analysis Dr. Mike Israel admits that he was wrong in how his advice on rep speed was perceived, acknowledging that his strong emphasis on slowing down the eccentric phase led many viewers to assume he advocated for "super slow training" for everyone (00:01, 02:59). He clarifies that the scientific literature indicates that eccentric phase times between 1 second and 6 seconds yield roughly equivalent hypertrophy benefits (07:59). The primary reasons he cues slower eccentrics (especially at the bottom of the movement) are for safety with his advanced, large-bodied clients whose tendons might lag behind muscle strength, increasing injury risk (03:44), and to maximize mind-muscle connection, ensuring muscles actively resist the weight rather than just falling due to gravity (05:15). For beginners or those learning a new technique, slowing down provides a crucial window for processing feedback cues, as fast eccentrics (like 0.5 seconds) mean feedback is received only after the rep is over (05:54). However, if an athlete is confident in their technique and connection, they are free to use fast concentric phases (1-2 seconds or rapid acceleration) without sacrificing growth, as the science suggests this range is equally effective (10:41). He stresses that intentionally slow concentrics are generally detrimental to training enjoyment ('sucks the f***ing life out of training'), but slower eccentrics can be used periodically for variation (11:13). ### Initial Admission - We flubbed - It's our bad - I was wrong about something, not because of the science, but because I am an egotistical, not nice person who shouldn't be swearing in YouTube videos (00:01, 00:39, 00:50) ### How This Got Started - The "slower is better" idea gained traction due to Dr. Mike and IFBB Pro Jared Feather consistently cueing pro bodybuilders to slow down eccentrics, especially at the bottom of the movement (00:54, 01:41, 02:14) ### The Reality - Why Slow Eccentrics are Cued - 1) Going slower is safer for gigantic, strong athletes who earn a living from their bodies (03:44); 2) Slower eccentrics increase mind-muscle connection, ensuring target muscle use (05:15); 3) Slower speed allows time to process technique cues on the fly (05:50) ### The Science Says - Anything between 1 and 6 seconds for the eccentric phase is roughly equivalent for growth (07:59); fast eccentrics (1-2s) on the concentric are fine if technique and safety are assured (09:38, 10:41) ### Conclusion - Fast eccentrics are fine if you are confident and actively resisting the weight; intentionally slow concentrics sap the enjoyment out of training, but slow eccentrics for variation are fine (10:50, 11:13, 09:09) ![Screenshot at 00:20: Dr. Mike Israel introduces himself as a PhD Sport Physiologist from RP Strength, preparing to discuss a past error in his advice \(00:20\)](https://ss.rapidrecap.app/screens/reiB9uQ6O4E/00-00-20.jpg) ![Screenshot at 00:47: On-screen text poses the central question: "WAS I WRONG ABOUT REP SPEED FOR MUSCLE GROWTH?" \(00:47\)](https://ss.rapidrecap.app/screens/reiB9uQ6O4E/00-00-47.jpg) ![Screenshot at 01:47: An image appears showing IFBB Pro Jared Feather \(left\) and Dr. Mike Israel \(right\), referencing the two individuals who popularized the 'slow is better' approach \(01:47\)](https://ss.rapidrecap.app/screens/reiB9uQ6O4E/00-01-47.jpg) ![Screenshot at 02:32: Visual demonstration of slow eccentric training, showing athletes performing controlled movements, contrasting with the discussion on fast eccentrics \(02:32\)](https://ss.rapidrecap.app/screens/reiB9uQ6O4E/00-02-32.jpg) ![Screenshot at 08:00: A slide appears detailing the scientific consensus: "Basically 'anything between 1 second to 6 seconds of eccentric phase is roughly equivalent for growth." \(08:00\)](https://ss.rapidrecap.app/screens/reiB9uQ6O4E/00-08-00.jpg)