The human body is a marvel, especially when it comes to its muscular system. Strength training plays a vital role in not only building muscle but also improving overall health and activities of daily living (aka ADL’s). Here are 10 key facts about muscle and lean muscle mass supported by scientific evidence.
1. Muscles Are the Body’s Engine
Muscles are responsible for movement, posture, and generating heat. They make up roughly 40 percent of total bodyweight, and their strength and efficiency can be significantly enhanced through resistance training. Research indicates that increased muscle mass improves metabolic health, aiding in better glucose regulation and fat metabolism.
2. Strength Training Increases Lean Muscle Mass
Strength training, also known as resistance training, is one of the most effective ways to increase lean muscle mass. By overloading muscles with weight or resistance, micro-tears in muscle fibers occur. These micro-tears repair stronger, leading to muscle hypertrophy. This process is crucial for anyone looking to build or maintain lean muscle mass.
3. Lean Muscle Mass Declines with Age
As we age, muscle mass naturally declines in a process known as sarcopenia. After age 30, adults can lose 3-5 percent of muscle mass per decade if they don’t engage in regular strength training. Strength training can help mitigate or even reverse this decline by promoting muscle growth and maintenance.
4. Muscle Growth Depends on Protein Synthesis
Muscle growth occurs when protein synthesis (the building of new muscle tissue) exceeds muscle protein breakdown. Resistance training stimulates muscle protein synthesis for up to 48 hours post-exercise. Consuming adequate protein after a workout can further enhance this process, promoting muscle repair and growth.
5. Type II Muscle Fibers are Most Affected by Strength Training
Muscles are composed of different types of fibers, with Type I fibers being endurance-oriented and Type II fibers being power-oriented. Strength training primarily targets Type II fibers, which are larger and more powerful. This leads to greater overall muscle size and strength gains.
6. Muscle Mass Boosts Metabolism
More muscle means a higher resting metabolic rate (RMR), which refers to the number of calories your body burns at rest. A 10-pound increase in lean muscle mass can raise RMR by approximately 50-100 calories per day. This is a key reason why strength training is recommended for weight management and fat loss.
7. Muscle Strength and Mass Protect Against Injury
Strong muscles support and stabilize joints, reducing the risk of injury during daily activities and physical exercise. Research shows that those with greater muscle mass and strength have a lower risk of musculoskeletal injuries, especially in older adults.
8. Muscle Enhances Insulin Sensitivity
Strength training improves insulin sensitivity, which helps the body utilize blood sugar more efficiently. This is particularly beneficial for those at risk of developing type 2 diabetes or managing insulin resistance. Lean muscle mass plays a crucial role in this process by aiding glucose uptake in response to insulin.
9. Consistent Strength Training Improves Bone Density
Resistance training not only strengthens muscles but also has a positive effect on bone density. The mechanical stress of lifting weights promotes bone remodeling, making bones stronger and less prone to fractures.
10. Recovery is Key to Building Muscle
Rest and recovery are crucial components of muscle growth. Muscles do not grow during the workout itself but during recovery. Adequate sleep, nutrition, and rest between strength training sessions allow the body to repair and build lean muscle.
11. What’s the Most Abundant Tissue in Our Body?
Skeletal muscle is the most abundant tissue in our body, accounting for approximately 42 and 35 percent of body weight in men and women respectively. In other words, an average male weighing 185 pounds has about 78 pounds of lean muscle tissue while a female weighing 140 pounds has approximately 49 pounds of lean muscle tissue (note: this is not an “exact” number).
12. Muscle Grows via Progressive Overload
One of the amazing things about muscle tissue is it has the ability, through progressive overload, to increase in size (known as muscle hypertrophy). Donnelly and colleagues have reported that strength training studies (lasting from 8 to 52 weeks) have shown increases of 2 to 5 pounds of muscle mass. In addition to increasing in size, muscle tissue also gets stronger with prolonged training. A periodized strength training program can elicit changes in endurance capacity, power output and force production while keeping sarcopenia at bay.
13. How is Muscle More Metabolically Active than Fat?
Lean muscle tissue requires 3-4 times more calories to maintain compared to fat and is important in the process of energy metabolism. A pound of metabolically active muscle tissue requires 5-7 calories per pound to maintain while less active fat tissue, requires only 2 calories per pound.
14. Why We All Need to be Strength Training as We Age
Lean muscle plays an important role in the aging process. With advancing age we experience a loss of exercise capacity. This is due to first, to a decline in skeletal muscle mass and strength during aging and then a decrease in maximal oxygen uptake, mainly due to a drop in maximal heart rate, according to Henning Wackerhage, PhD, a Senior Lecturer in Molecular Exercise Physiology at the University of Aberdeen.
15. Build More Muscle
Protein stores found in muscle can account for about 30,000 calories of energy. Muscle tissue can contribute approximately 20 percent of the body’s total daily energy expenditure compared to 5 percent for fat tissue (it would be great if we could tap into those fat stores more often).
Conclusion
Strength training is an essential component of building and maintaining lean muscle mass. The benefits extend beyond aesthetics, improving metabolic health, protecting against injury, and promoting long-term wellness. By incorporating regular strength training into your fitness routine, you can optimize your muscle growth and overall health.
One thing is for certain, everyone wants more lean muscle and less body fat. Regular strength training is a much needed critical component for everything from health to activities of daily living. Check out some of the many great strength training routines found on Jefit, like the FitBody Plan.
References
Wolfe, R. R. (2006). The underappreciated role of muscle in health and disease. The American Journal of Clinical Nutrition, 84(3), 475-482.
Carbone, J. W., & Pasiakos, S. M. (2019). Dietary protein and muscle mass: Translating science to application and health benefit. Nutrients, 11(5), 1136.
Phillips, S. M. (2014). A brief review of critical processes in exercise-induced muscular hypertrophy. Sports Medicine, 44(1), 71-77.
Cruz-Jentoft, A. J., & Sayer, A. A. (2019). Sarcopenia. The Lancet, 393(10191), 2636-2646.
Damas, F., Phillips, S. M., Libardi, C. A., et al. (2016). Resistance training-induced changes in integrated myofibrillar protein synthesis are related to hypertrophy only after attenuation of muscle damage. The Journal of Physiology, 594(18), 5209-5222.
Liu, Y., Heinonen, I., Reiss, I., et al. (2020). Type II muscle fiber atrophy and associated myonuclear depletion do not occur in long-term endurance-trained master athletes. American Journal of Physiology-Cell Physiology, 318(6), C1307-C1315.
Stiegler, P., & Cunliffe, A. (2006). The role of diet and exercise for the maintenance of fat-free mass and resting metabolic rate during weight loss. Sports Medicine, 36(3), 239-262.
Heiss, R., Freiwald, J., Mayer, F., et al. (2017). Influence of training load and transfer between strength, power, and speed training. Journal of Strength and Conditioning Research, 31(7), 1861-1866.
Horta, B. L., Silveira, M. F., Bertoldi, A. D., et al. (2019). Prevalence of muscle-strengthening activity among adults and its association with chronic diseases. Journal of Physical Activity and Health, 16(6), 434-440.
Asadi, A., Arazi, H., Young, W. B., & Saez de Villarreal, E. (2016). Effects of accommodating resistance training on strength, power, and physical performance. Journal of Strength and Conditioning Research, 30(2), 352-367.
Additional References
Haun, C. T., Vann, C. G., Osburn, S. C., & Mumford, P. W. (2019). Muscle fiber hypertrophy in response to 6 weeks of high-volume resistance training. Frontiers in Physiology, 10, 123.
Marieb, EN and Hoehn, K. (2010). Human Anatomy and Physiology (8th ed.). San Francisco: Benjamin Cummings.
Elia, M. (1999). Organ and Tissue Contribution to Metabolic Weight. Energy Metabolism: Tissue Determinants and Cellular Corollaries. Kinney, J.M., Tucker, H.N., eds. Raven Press. New York.
Donnelly, J.E., Jakicic, J.M., et. al. (2003). Is Resistance Training Effective for Weight Management Evidence-Based Preventive Medicine. 1(1): 21-29.
Wackerhage, H. (2014). Molecules, Aging and Exercise in Molecular Exercise Physiology. Routledge.
Wood, M. (2018). TBC30: 6 Steps to a Stronger and Healthier You. Wicked Whale Publishing, 2nd edition.
Coyle, EF. (1995). Fat metabolism during exercise. Sports Science Exchange, 8(6):59.
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