Debunking Muscle Growth Myths: Insights from New Research Summary
- A recent review has debunked some of the biggest muscle growth myths. It challenges traditional beliefs about slow and controlled reps for optimal muscle growth; the review suggests that muscle growth can occur over a wide range of repetition durations (0.5 to 8 seconds) and that the tempo of repetitions, specifically the balance between slow eccentric and faster concentric phases, may not be as critical as previously thought for optimizing hypertrophy.
- Moreover, performing partial range of motion (ROM) exercises at longer muscle lengths could prove superior to full ROM exercises for promoting muscle hypertrophy. This indicates that we might need to reevaluate the traditional emphasis on full ROM for all exercises based on specific muscle groups and training goals.
- While important for biomechanical efficiency and injury prevention, exercise-specific kinematics, including detailed body positioning and movement patterns, may not directly correlate with muscle hypertrophy outcomes, indicating a need for more research on how strict versus non-strict repetition techniques affect muscle growth.
Muscle Growth Myths
Muscle hypertrophy, or the increase in muscle size, is a primary goal of those going to the gym regularly. Effective weightlifting requires the manipulation of variables such as training volume, intensity of effort, and range of motion (ROM).(Brad et al., 2021; Schoenfeld, 2010) Despite the wealth of conventional wisdom, a narrative review by Androulakis provides a comprehensive analysis of existing research on the topic, exploring the impact of various weight lifting modalities, including eccentric tempo, ROM, and exercise-specific kinematics on muscle hypertrophy. The article challenges long-standing muscle growth myths about techniques for optimizing muscle growth.(Androulakis Korakakis et al., 2024)
Muscle Growth Myth 1: Slow and Controlled Reps Are Key for Muscle Growth
The debate over the repetition tempo, or how fast you lift a weight, has seen many fitness professionals advocate for slow, controlled reps as the optimal approach for muscle hypertrophy. The prevailing thought was that taking longer to lift and lower weights, particularly by extending the eccentric phase (where the muscle lengthens), would enhance muscle growth by increasing time under tension. This concept was based on the belief that longer tension would lead to more significant muscle damage and, thus, more considerable repair and growth.
However, a review by Schoenfeld et al. discovered that muscle growth occurs across a broad range of repetition durations, from 0.5 to 8 seconds, suggesting that repetition tempo (i.e., lifting speed) may not be as critical as previously thought. (Schoenfeld et al., 2015) Wilk et al.’s findings propose that a combination of slower eccentric and faster concentric tempos could be optimal for muscle development. However, a definitive tempo recommendation remains elusive due to the diversity in study protocols.(Schoenfeld et al., 2015) These insights challenge the dogma that slow, controlled reps are superior, indicating that significant hypertrophy can occur within 2 to 8 seconds of repetition durations, regardless of whether the concentric or eccentric phase is extended.
Recommendations: To debunk this muscle growth myth, trainers should consider incorporating a variety of repetition tempos. The authors recommend a repetition tempo of 2-8 seconds to maximize hypertrophy, although it remains unclear whether extending a repetition’s concentric or eccentric phase will lead to greater hypertrophy.
Muscle Growth Myth 2: All Muscles Need to be trained with a Full Range of Motion for Optimal Muscle Growth
The second muscle growth myth insists on the importance of employing a full ROM in every exercise to ensure maximum muscle engagement and hypertrophy. The insistence on utilizing a full range of motion for all exercises is another widely held belief in resistance training, grounded in the idea that full ROM maximizes muscle engagement and growth by moving through the muscle’s entire length. This concept was particularly emphasized for exercises like squats, bench presses, and calf raises, where a full stretch and contraction were thought to ensure optimal hypertrophy.
Recent reviews have sparked a reevaluation of the necessity for a full ROM in training. Wolf et al. found that a partial ROM performed at longer muscle lengths might be superior to a full ROM for hypertrophy. (Milo et al., 2023) Kassiano et al. corroborated this, showing that a partial ROM at long muscle lengths could promote optimal growth in muscles like the quadriceps, biceps, and triceps. (Kassiano et al., 2023) These findings suggest that employing a ROM that favors longer muscle lengths could be more beneficial than adhering strictly to a full ROM.
Recommendations: It’s time to move past this muscle growth myth by advocating for exercises that allow muscles to extend fully, particularly focusing on longer muscle lengths, to foster better hypertrophy results. The authors recommend employing a range of motion (ROM) that emphasizes training at long muscle lengths (deep stretch) to maximize muscle hypertrophy. They suggest using a full ROM, defined as the largest exercise-specific degree of ROM that can be achieved at each joint, to optimize hypertrophic outcomes.
Muscle Growth Myth 3: Exercise-Specific Kinematics Determine Muscle Growth
The final muscle growth myth to be debunked is the notion that strict adherence to exercise-specific kinematics—precise body alignment and positioning—is directly correlated with achieving muscle hypertrophy. Exercise-specific kinematics, including precise instructions on body alignment, positioning, and movement patterns, have been emphasized for their importance in ensuring effective and safe resistance training. These guidelines, often based on biomechanical principles, are designed to optimize the mechanical efficiency of an exercise and minimize injury risk.
Strict adherence to these guidelines was also thought to maximize hypertrophy by ensuring that the target muscles are engaged correctly and fully. However, the evidence does not support the direct correlation between these strict kinematic guidelines and muscle hypertrophy.
Direct studies on the topic, such as one exploring the effect of different foot positions during calf training, indicate that while certain positions can influence hypertrophy in specific muscle areas, muscle activation alone may not be a reliable hypertrophy predictor.(Andersen et al., 2014; Martín-Fuentes et al., 2022; Nunes et al., 2020; Saeterbakken et al., 2021) This lack of direct evidence challenges the notion that strict adherence to specific kinematic guidelines is essential for hypertrophy, suggesting that there might be more flexibility in effective resistance training techniques than previously thought.
Muscle Growth Myths: Practical Applications
Given the current evidence, resistance training programs designed to maximize muscle hypertrophy should:
- Employ a ROM that allows a muscle to be fully stretched, accommodating for longer muscle lengths where possible.
- Utilize a repetition tempo that spans an overall duration of 2–8 seconds, allowing for various concentric and eccentric durations. This flexibility accommodates a wide spectrum of effective training methodologies.(Milo et al., 2023; Schoenfeld et al., 2015; Wilk et al., 2021)
Conclusions
In conclusion, debunking these muscle growth myths embraces a nuanced approach to resistance training that acknowledges the complexity of muscle hypertrophy. By adapting training techniques based on scientific evidence, practitioners can explore a broader range of effective strategies tailored to individual goals and needs.
References
Andersen, V., Fimland, M. S., Wiik, E., Skoglund, A., & Saeterbakken, A. H. (2014). Effects of Grip Width on Muscle Strength and Activation in the Lat Pull-Down. The Journal of Strength & Conditioning Research, 28(4), 1135-1142. https://doi.org/10.1097/jsc.0000000000000232
Androulakis Korakakis, P., Wolf, M., Coleman, M., Burke, R., Piñero, A., Nippard, J., & Schoenfeld, B. J. (2024). Optimizing Resistance Training Technique to Maximize Muscle Hypertrophy: A Narrative Review. Journal of Functional Morphology and Kinesiology, 9(1), 9. https://www.mdpi.com/2411-5142/9/1/9
Brad, S., James, F., Jozo, G., Cody, H., Eric, H., Stuart, P., James, S., & Andrew, V. (2021). Resistance Training Recommendations to Maximize Muscle Hypertrophy in an Athletic Population: Position Stand of the IUSCA. International Journal of Strength and Conditioning, 1(1). https://doi.org/10.47206/ijsc.v1i1.81
References
Kassiano, W., Costa, B., Nunes, J. P., Ribeiro, A. S., Schoenfeld, B. J., & Cyrino, E. S. (2023). Which ROMs Lead to Rome? A Systematic Review of the Effects of Range of Motion on Muscle Hypertrophy. The Journal of Strength & Conditioning Research, 37(5), 1135-1144. https://doi.org/10.1519/jsc.0000000000004415
Martín-Fuentes, I., Oliva-Lozano, J. M., & Muyor, J. M. (2022). Influence of Feet Position and Execution Velocity on Muscle Activation and Kinematic Parameters During the Inclined Leg Press Exercise. Sports Health, 14(3), 317-327. https://doi.org/10.1177/19417381211016357
Milo, W., Patroklos, A.-K., James, F., Brad, S., & James, S. (2023). Partial Vs Full Range of Motion Resistance Training: A Systematic Review and Meta-Analysis. International Journal of Strength and Conditioning, 3(1). https://doi.org/10.47206/ijsc.v3i1.182
Nunes, J. P., Costa, B. D. V., Kassiano, W., Kunevaliki, G., Castro-e-Souza, P., Rodacki, A. L. F., Fortes, L. S., & Cyrino, E. S. (2020). Different Foot Positioning During Calf Training to Induce Portion-Specific Gastrocnemius Muscle Hypertrophy. The Journal of Strength & Conditioning Research, 34(8), 2347-2351. https://doi.org/10.1519/jsc.0000000000003674
Saeterbakken, A. H., Stien, N., Pedersen, H., Solstad, T. E., Cumming, K. T., & Andersen, V. (2021). The Effect of Grip Width on Muscle Strength and Electromyographic Activity in Bench Press among Novice- and Resistance-Trained Men. International Journal of Environmental Research and Public Health, 18(12).
Schoenfeld, B. J. (2010). The Mechanisms of Muscle Hypertrophy and Their Application to Resistance Training. The Journal of Strength & Conditioning Research, 24(10), 2857-2872. https://doi.org/10.1519/JSC.0b013e3181e840f3
Schoenfeld, B. J., Ogborn, D. I., & Krieger, J. W. (2015). Effect of Repetition Duration During Resistance Training on Muscle Hypertrophy: A Systematic Review and Meta-Analysis. Sports Medicine, 45(4), 577-585. https://doi.org/10.1007/s40279-015-0304-0
Wilk, M., Zajac, A., & Tufano, J. J. (2021). The Influence of Movement Tempo During Resistance Training on Muscular Strength and Hypertrophy Responses: A Review. Sports Medicine, 51(8), 1629-1650. https://doi.org/10.1007/s40279-021-01465-2