Recapping 2024’s Most Notable Muscle-Building Studies

2024 brought groundbreaking exercise science that challenges previous notions of building strength and muscle growth. House of Hypertrophy delved into 2024’s key research findings on training to failure, optimal range of motion, and ideal set volume. 

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Training to Failure or Not?

Training close to failure maximizes muscle fiber recruitment and creates muscle tension, but pushing to failure may not always be necessary for optimal results.

A recent study using trained individuals with significant experience in failure-based training had them perform unilateral exercises, including leg extensions and leg presses. (1)

They trained for momentary muscular failure on one leg and stopped one rep short of failure on leg extensions and two repetitions short on leg presses for the other leg. The findings revealed similar quad growth in both cases, suggesting that stopping one to two reps shy of failure may still be effective for muscle hypertrophy. Additional well-designed studies further support this conclusion. (2)(3)(4)

Consider training volume. In the primary study mentioned, participants maintained their pre-study training volume with a 20% increase midway through, completing 10 to 17 weekly sets targeting their quads. So, is training to failure more advantageous when the number of sets is lower? 

Another study examined the impact of failure training on individuals who performed one set per exercise. (5) Forty-two trained participants followed the same program twice per week. One group trained each set to momentary muscular failure, the other stopped with two reps in reserve.

Although the results were inconclusive, training to failure showed a slight advantage in most measurements. An additional study found better muscle growth when training to failure than stopping short, but only when performing a single set per exercise. (6)

In conclusion, stopping short of failure is often sufficient for hypertrophy, but training to failure might provide a marginal benefit in scenarios with lower training volume. The optimal approach depends on the number of sets, training frequency, and individual goals.

Partial or Full Range of Motion?

What is the best range of motion for building muscle? Full range of motion (ROM) moves a joint or body part through its entire functional range. Partial range of motion limits movement to only a portion of that range. Within partial ROM, “lengthened partials” refer to movements focused on the stretch or lengthened position of the muscle.

For years, full range of motion was considered superior — primarily due to comparisons with shortened partials. However, recent studies suggest lengthened partials may stimulate more muscle growth than a full ROM. Research of untrained individuals found that exercises like calf raises, leg extensions, and hip extensions performed with lengthened partials produced better muscle-building results. (7)(8)

A study involving nearly 300 participants with at least six months of training experience were trained twice per week for, performing one set per exercise to momentary failure. One group used a full ROM for all exercises. The other combined lengthened partials of some movements with full ROM for others.

The results showed similar increases in both groups’ arm and thigh muscle growth, suggesting that lengthened partials are as effective as a full ROM for trained individuals. (9) Another study, co-sponsored by Jeff Nippard, found comparable muscle growth in subjects training with full ROM versus those using a combination of full ROM and lengthened partials. (10)

In summary, while full ROM remains a practical approach, lengthened partials are a promising alternative, particularly for targeting specific ranges of muscle activation. Depending on the individual and the exercise, both methods have the potential to yield comparable results.

How Many Sets?

How many sets for optimal growth? This year brought us the most comprehensive analysis of this question to date, with findings that suggest performing more sets generally leads to more significant muscle growth. However, strength gains can still be achieved with significantly fewer sets. (11)

Training with intensity and prioritizing quality over quantity can optimize muscle growth. Choose exercises that effectively target specific muscles and aim for 12 to 20 sets per muscle group each week.

Other Studies

2024 found fascinating developments in muscle physiology, including research investigating whether muscles might compete for growth. (12) One study suggested that untrained muscles may shrink to support the growth of trained muscles. (13)

Muscle hyperplasia — the increase in muscle fibers — remains a topic of debate. Measuring muscle fiber numbers in humans is notoriously tricky, one study attempted to estimate these numbers using a specialized equation. While these findings provide intriguing insights, more research is needed to draw meaningful conclusions. (14)

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References

1. Refalo, M. C., Helms, E. R., Robinson, Z. P., Hamilton, D. L., & Fyfe, J. J. (2024). Similar muscle hypertrophy following eight weeks of resistance training to momentary muscular failure or with repetitions-in-reserve in resistance-trained individuals. Journal of sports sciences, 42(1), 85–101. https://doi.org/10.1080/02640414.2024.2321021
2. Nóbrega, S. R., Ugrinowitsch, C., Pintanel, L., Barcelos, C., & Libardi, C. A. (2018). Effect of Resistance Training to Muscle Failure vs. Volitional Interruption at High- and Low-Intensities on Muscle Mass and Strength. Journal of strength and conditioning research, 32(1), 162–169. https://doi.org/10.1519/JSC.0000000000001787 
3. Lacerda, L. T., Marra-Lopes, R. O., Diniz, R. C. R., Lima, F. V., Rodrigues, S. A., Martins-Costa, H. C., Bemben, M. G., & Chagas, M. H. (2020). Is Performing Repetitions to Failure Less Important Than Volume for Muscle Hypertrophy and Strength?. Journal of strength and conditioning research, 34(5), 1237–1248. https://doi.org/10.1519/JSC.0000000000003438 
4. Santanielo, N., Nóbrega, S. R., Scarpelli, M. C., Alvarez, I. F., Otoboni, G. B., Pintanel, L., & Libardi, C. A. (2020). Effect of resistance training to muscle failure vs non-failure on strength, hypertrophy and muscle architecture in trained individuals. Biology of sport, 37(4), 333–341. https://doi.org/10.5114/biolsport.2020.96317
5. Hermann, T., Mohan, A., Enes, A., Sapuppo, M., Pinero, A., Zamanzadeh, A., . . . Schoenfeld, B. (2024). Without fail: muscular adaptations in single set resistance training performed to failure or with repetitions-in-reserve. Without Fail: Muscular Adaptations in Single Set Resistance Training Performed to Failure or With Repetitions-in-reserve. https://doi.org/10.51224/srxiv.484
6. Gieβsing, J., Fisher, J., Steele, J., Rothe, F., Raubold, K., & Eichmann, B. (2016). The effects of low-volume resistance training with and without advanced techniques in trained subjects. The Journal of sports medicine and physical fitness, 56(3), 249–258.
7. Pedrosa, G. F., Lima, F. V., Schoenfeld, B. J., Lacerda, L. T., Simões, M. G., Pereira, M. R., Diniz, R. C. R., & Chagas, M. H. (2022). Partial range of motion training elicits favorable improvements in muscular adaptations when carried out at long muscle lengths. European journal of sport science, 22(8), 1250–1260. https://doi.org/10.1080/17461391.2021.1927199
8. Kassiano, W., Costa, B., Kunevaliki, G., Soares, D., Zacarias, G., Manske, I., Takaki, Y., Ruggiero, M. F., Stavinski, N., Francsuel, J., Tricoli, I., Carneiro, M. A. S., & Cyrino, E. S. (2023). Greater Gastrocnemius Muscle Hypertrophy After Partial Range of Motion Training Performed at Long Muscle Lengths. Journal of strength and conditioning research, 37(9), 1746–1753. https://doi.org/10.1519/JSC.0000000000004460
9. Carlson, L., Gschneidner, D., Steele, J., & Fisher, J. (2024). The effects of lengthened-partial range of motion resistance training of the limbs on arm and thigh muscle cross-sectional area. The Effects of Lengthened-partial Range of Motion Resistance Training of the Limbs on Arm and Thigh Muscle Cross-sectional Area. https://doi.org/10.51224/srxiv.485
10. Wolf, M., Korakakis, P. A., Piñero, A., Mohan, A. E., Hermann, T., Augustin, F., . . . Schoenfeld, B. J. (2024). Lengthened partial repetitions elicit similar muscular adaptations as a full range of motion during resistance training in trained individuals. Lengthened Partial Repetitions Elicit Similar Muscular Adaptations as a Full Range of Motion During Resistance Training in Trained Individuals. https://doi.org/10.51224/srxiv.455
11. Pelland, N. J., Remmert, N. J., Robinson, N. Z., Hinson, N. S., & Zourdos, N. M. (2024b). The Resistance Training Dose-Response: Meta-Regressions exploring the effects of weekly volume and frequency on muscle hypertrophy and strength gain. The Resistance Training Dose-Response: Meta-Regressions Exploring the Effects of Weekly Volume and Frequency on Muscle Hypertrophy and Strength Gain. https://doi.org/10.51224/srxiv.460
12. Kataoka, R., Yamada, Y., Hammert, W. B., Kang, A., & Loenneke, J. P. (2024). Do skeletal muscles compete with each other for growth? Medical Hypotheses, 111525. https://doi.org/10.1016/j.mehy.2024.111525
13. VAN Vossel, K., Hardeel, J., VAN DER Stede, T., Cools, T., Vandecauter, J., Vanhaecke, L., Boone, J., Blemker, S. S., Lievens, E., & Derave, W. (2024). Evidence for Simultaneous Muscle Atrophy and Hypertrophy in Response to Resistance Training in Humans. Medicine and science in sports and exercise, 56(9), 1634–1643. https://doi.org/10.1249/MSS.0000000000003475
14. Maeo, S., Balshaw, T. G., März, B., Zhou, Z., Haug, B., Martin, N. R. W., Maffulli, N., & Folland, J. P. (2024). Long-Term Resistance Trained Human Muscles Have More Fibers, More Myofibrils, and Tighter Myofilament Packing Than Untrained. Medicine and science in sports and exercise, 56(10), 1906–1915. https://doi.org/10.1249/MSS.0000000000003495

Featured image via Shutterstock/ThomsonD