Cell Swell! Light Weight Exercise More Effective than Heavy Weights for Skeletal Muscle Pumps Summary
- The study investigated whether light weight exercise was more effective for skeletal muscle pumps and cell swelling than heavy weights.
- Both light and heavy weight protocols effectively increased muscle thickness and blood lactate levels.
- The lighter-weight protocol significantly impacted muscle thickness (i.e., muscle pump), cell swelling, total repetitions, time under tension, and training density.
- Both light and heavy weight training can generate a favorable environment for muscle cell swelling, although light weight showed greater post-session increases in muscle thickness and lactate concentration.
Skeletal Muscle Pump vs No Pump
When it comes to building muscle, the common belief is that lifting heavy is the only way to go for muscle growth. But what if lighter weights could offer similar benefits and result in greater skeletal muscle pumps? Recent studies have shown that light weight exercises can be more effective in achieving skeletal muscle pumps than heavy weights. A recent study in the International Journal of Exercise Science turns this assumption on its head, revealing intriguing insights into skeletal muscle pumps and resistance training.(Agentilho et al., 2023)
Understanding the Concept of Skeletal Muscle Pumps
Skeletal muscle pumps, also known as transient hypertrophy, is the result of intensified blood flow to working muscles, leading to cell swelling. This transient means of muscle growth stimulation is achieved through intense muscle pumps during training. Muscle pump training can effectively enhance the pump, maximizing the net effect on muscle fibers. Understanding the concept of muscle pump is crucial for bodybuilders seeking the best way to achieve a great muscle pump.
The Science Behind Skeletal Muscle Pumps: Tension, Metabolic Stress, and Cell Swelling
Placing tension on the muscle is known to elicit muscle hypertrophy (i.e., muscle growth) by activating anabolic signaling pathways. (Schoenfeld, 2010) Additionally, metabolic stress (i.e., increases in anaerobic metabolism) has been hypothesized to play a significant role in resistance training-induced muscle growth. (Pearson & Hussain, 2015)
Metabolic stress in bodybuilding can be described as the physiological stress placed on muscles during intense exercise that leads to various metabolic changes. It’s often associated with the “burn” you feel during high-repetition resistance training exercises. This sensation results from the accumulation of metabolic byproducts, like lactate, and decreased oxygen and energy stores within the muscle. Studies suggest that bodybuilding protocols designed to heighten metabolic stress can increase muscle growth compared to those inducing less metabolic stress. (Goto et al., 2005)
While training with heavy weights is well-established in inducing significant muscle growth, evidence shows that lighter-weight training can promote similar muscle growth, possibly mediated by metabolite accumulation. (Ozaki et al., 2016) Acute cell swelling associated with metabolic stress, or “the pump,” is hypothesized to contribute to the hypertrophic response in light weight training. (de Freitas et al., 2017; Schoenfeld & Contreras, 2014)
Studies in test tubes with muscle cells indicate that cell swelling or increases in fluid into the cells leads to increased protein synthesis, decreased protein breakdown in various tissues (Lang et al., 1998), and activation of anabolic signaling pathways. (Schoenfeld, 2013) A good pump can induce cell swelling, which may increase amino into muscle cells, further contributing to muscle growth. (Low et al., 1997)
Does Heavy Weight or Light Weight Training Result in Greater Skeletal Muscle Pumps?
A recent compared the effects of light weight and heavy weight resistance training on muscle growth, particularly focusing on cell swelling, a key factor in muscle growth. Eight resistance-trained males were put to the test, performing bicep curl exercises under both light and heavy-weight protocols.
- The light weight protocol consisted of 4 sets of single-arm biceps curls at 50% of 1 repetition maximum (1RM) until volitional failure.
- The heavy-weight protocol involved 10 sets at 85% of 1RM until volitional failure.
- Both protocols were volume-equated, meaning the total work (repetitions x load) was matched between conditions. Ultrasound measurements to measure changes in muscle size were taken on the exercised arm both before and within ten minutes after the exercise protocol.
The key metrics studies were muscle thickness of the biceps, arm circumference, and blood lactate concentration.
What’s the Difference Between Arm Circumference and Muscle Thickness?
Arm Circumference:
What It Measures: Arm circumference measures the arm’s total girth at a specific point, usually around the largest part of the biceps and triceps.
Indicators: It reflects muscle mass and subcutaneous fat, skin, and potentially fluid accumulation in the area. This makes it a more general indicator of overall arm size rather than muscle size alone.
Measurement Technique: It is typically measured using a flexible measuring tape. This method is non-invasive, easy to perform, and requires minimal equipment.
Muscle Thickness
What It Measures: Muscle thickness specifically measures the size of a muscle or muscle group, typically using ultrasound imaging. It provides a direct indication of muscle hypertrophy (growth).
Indicators: As it measures only the muscle, it is a more specific indicator of muscle growth and muscle mass changes unaffected by fat or fluid variations.
Measurement Technique: Ultrasound imaging is the standard method for measuring muscle thickness. This technique is more technical, requires specialized equipment, and usually a trained operator.
Results
- Both light and heavy-weight protocols led to significant increases in muscle thickness (i.e., muscle pumps) and blood lactate concentration.
- Surprisingly, the light weight protocol showed greater muscle thickness, total repetitions, time under tension, and training density.
- These findings suggest that light weight training, with its longer times under tension and higher training densities, is more effective in promoting acute cell swelling (i.e., muscle pumps).
Interpretation: Greater Skeletal Muscle Pumps with Lighter Weights:
The increase in muscle thickness was more pronounced in the light weight group than in the heavy-weight group. Light weight training, often considered less strenuous, resulted in a larger increase in muscle thickness, which challenges conventional wisdom in resistance training.
Another interesting finding was that both training protocols showed significant increases in blood lactate concentration. It’s particularly noteworthy that the lighter-weight training, which is typically less intense, resulted in a higher percentage increase in lactate (163.6% vs. 105.48% in heavy-weight). Lighter-weight, high-repetition training produces a more pronounced and sustained skeletal muscle pump than heavy-weight training. This is due to longer muscle tension time, increased metabolic stress, and sustained blood flow.
References
Agentilho, G. I., EGP, D. E. L., Teixeira, L. F. M., Boas, V. V., Ribeiro, I. C., Barroso, R., Schoenfeld, B. J., & Uchida, M. C. (2023). Low-Load x High-Load Resistance Exercise: Greater Cell Swelling After a Training Session. Int J Exerc Sci, 16(3), 513-524.
de Freitas, M. C., Gerosa-Neto, J., Zanchi, N. E., Lira, F. S., & Rossi, F. E. (2017). Role of metabolic stress for enhancing muscle adaptations: Practical applications. World J Methodol, 7(2), 46-54. https://doi.org/10.5662/wjm.v7.i2.46
Goto, K., Ishii, N., Kizuka, T., & Takamatsu, K. (2005). The impact of metabolic stress on hormonal responses and muscular adaptations. Med Sci Sports Exerc, 37(6), 955-963.
Lang, F., Busch, G. L., Ritter, M., Völkl, H., Waldegger, S., Gulbins, E., & Häussinger, D. (1998). Functional significance of cell volume regulatory mechanisms. Physiol Rev, 78(1), 247-306. https://doi.org/10.1152/physrev.1998.78.1.247
Low, S. Y., Rennie, M. J., & Taylor, P. M. (1997). Signaling elements involved in amino acid transport responses to altered muscle cell volume. Faseb j, 11(13), 1111-1117. https://doi.org/10.1096/fasebj.11.13.9367345
Ozaki, H., Loenneke, J. P., Buckner, S. L., & Abe, T. (2016). Muscle growth across a variety of exercise modalities and intensities: Contributions of mechanical and metabolic stimuli. Med Hypotheses, 88, 22-26. https://doi.org/10.1016/j.mehy.2015.12.026
Pearson, S. J., & Hussain, S. R. (2015). A review on the mechanisms of blood-flow restriction resistance training-induced muscle hypertrophy. Sports Med, 45(2), 187-200. https://doi.org/10.1007/s40279-014-0264-9
Schoenfeld, B. J. (2010). The mechanisms of muscle hypertrophy and their application to resistance training. J Strength Cond Res, 24(10), 2857-2872. https://doi.org/10.1519/JSC.0b013e3181e840f3
Schoenfeld, B. J. (2013). Potential mechanisms for a role of metabolic stress in hypertrophic adaptations to resistance training. Sports Med, 43(3), 179-194. https://doi.org/10.1007/s40279-013-0017-1
Schoenfeld, B. J., & Contreras, B. (2014). The Muscle Pump: Potential Mechanisms and Applications for Enhancing Hypertrophic Adaptations. Strength & Conditioning Journal, 36(3). https://journals.lww.com/nsca-scj/fulltext/2014/06000/the_muscle_pump__potential_mechanisms_and.11.aspx
Additional Information
Arnold Schwarzenegger’s strength training approach, combined isolation and compound exercises with short rest periods and progressive overload, maximizes blood flow and nitric oxide production. Techniques like drop sets, blood flow restriction training, and superset training enhance muscle contraction and the skeletal muscle pump. Citrulline malate supplements, along with proper nutrition, including carbs, creatine, and glycogen, support muscle protein synthesis and endurance. This regimen, focusing on tempo, rep range, and shorter rest periods, boosts lactic acid build-up and stroke volume, aiding in weight loss and improving physique through increased muscle tissue and stamina.
