Whether in the pursuit of sports performance, improving your health or simply trying to look good naked, muscle growth is a common goal for many of us. While it is true that there are a thousand ways to skin a cat and many different programs will result in increased muscle size and strength, there are several tenets that separate a great program from an OK one. When it comes to increase muscular size, proper implementation of these five tenets will make your program the most effective.
1.) Mechanical Tension
Mechanical tension is one of the primary drivers of muscular hypertrophy1-4. The tension placed on muscle fibers during resistance training is thought to act through several channels including:
- Increasing satellite cell activity5,6.
Satellite cells are myogenic stem cells that contribute their nucleus to damaged muscle fibers. The nucleus contains all the genetic information for encoding proteins and the contribution of more nuclei to a muscle fiber helps increase its myonuclear domain allowing for the creation of greater amounts of protein and the maintenance of a larger cross-sectional areas of muscle.
- Up-regulating the AKT/mTOR pathway.
This pathway is not only one of the primary drivers of muscular anabolism, but it also prevents the breakdown of muscle tissue as well7,8.
- Increased motor unit firing frequency.
Increased motor unit firing frequency will not only aid in neurological improvements, but leads to increased calcium release from muscle fibers that signal downstream calcium dependent signaling pathways that are necessary for the growth of all muscular tissues9.
Higher loads require greater amounts of force generation and motor unit firing which leads to increased levels of active tension and enhanced signaling of protein synthetic pathways. In addition, passive muscular tension developed as a muscle contractile unit is stretch has a hypertrophic effect specific to fast-twitch fibers which have the greatest potential for strength, power, and size5.
This is a possible explanation for the superiority of eccentric based training on muscular hypertrophy as it allows for the handling of greater loads than can be utilized concentrically generating very high amounts of active tension and motor unit firing while also creating high amounts of passive tension as the loaded muscle fibers are lengthened10-20. To learn more about eccentric-based training methods, check out our post here.
While muscular tension is important to muscular hypertrophy, tension alone won’t maximize muscle growth. In fact, large amounts of tension without increased muscular damage and stress can lead to great gains in strength and power without large increases in muscle size which can be helpful to weight class sports and improvements in relative strength3 , but not for those looking to gain significant amounts of mass. For improvements in muscle growth, however, it is recommended that loads of at least 65% 1RM be utilized to cause significant enough disturbances of muscle fibers to cause the signaling of the metabolic pathways necessary for growth21.
2.) Muscular Damage
Muscle damage is another of the three primary stimulators of muscle growth1,22. Microtraumas to muscle fibers occur as a result of resistance training. These microtraumas can occur to the actual contractile elements of the motor unit or the connective tissue surrounding it.
The result of this damage is an inflammatory response that attracts immune cells, such as macrophages and lymphocytes, to the area. These macrophages release cytokines, locally released signaling molecules, that activate myoblasts that can then release growth factors that can increase the proliferation of satellite cells and promote their differentiation into muscle fibers5,23.
Insulin -like Growth Factor 1(IGF-1) and its isoform, mechano growth factor (MGF), two of the bodies most powerful anabolic hormones, are also particularly sensitive to mechanic tension and muscle damage. Furthermore, muscular damage and mechanical tension are both contributors to the Mitogen-Activated Protein-Kinase Pathway (MAPK), specifically that of c-Jun NH2-terminal kinase2,6.
This pathway regulates gene expression in response to stress and is particularly effected by eccentric-based training, likely because it leads to greater amounts of both mechanical tension and muscular damage24,25.
One of the keys to increasing muscular damage is gaining greater amounts of Time Under Tension (TUT) through either increased volume or a slower pace of movement. More TUT will provide greater amounts of stress to the muscle fibers leading to increased amounts of muscle damage.
3.) Metabolic Stress
While possibly not essential to muscle growth26, metabolic stress, when incorporated correctly, may be an athletes best tool in stimulating muscle growth. Metabolic stress is caused by the creation of a hypoxic environment in the muscle cell and the accumulation of metabolic by-products from anaerobic metabolism, such as lactate and increased concentrations of hydrogen ions leading to increased acidity of the muscle fiber1,3,27-29.
All of these factors contribute to increased release of hormones such as growth hormone and testosterone as well as the accumulation of blood within the muscle due to increased blood flow to the working muscle and the partial occlusion of veins during contraction, commonly termed “the pump.” While this “pump” will cause temporary swelling of the muscle that will go away with time, the stress caused on the cell membranes of muscle cells may stimulate changes in the muscle fiber, with fast-twitch fibers showing the greatest sensitivity to this type of stress30.
To generate greater amounts of metabolic stress, we must tax our bodies anaerobic metabolism through longer durations of high intensity, anaerobic work. Shortened rest periods can also lead to greater amounts of metabolic stress by preventing the body from fully recovering between sets.
4.) Excess Nutritional Energy
While mechanical tension, muscle damage and metabolic stress are all necessary for stimulating hypertrophy, without adequate energy from food, measured in calories (kcal), growth will not happen. In other words, you have to eat big to get big. Muscle is a very metabolically demanding tissue and the body is reluctant too add higher levels of muscle due to the cost of maintaining it. It is important to think of muscle growth in the following way:
Protein Synthesis – Protein Breakdown = Net Protein Accumulation
Without a surplus of energy, our body may initiate hypertrophic pathways causing increased protein synthesis, however, levels of protein breakdown will outweigh these increases yielding little to no increase in net protein. A surplus of around 350-500kcal is typically recommended to create improvements in muscle growth when you are first starting31. Muscle growth is a slow process and everybody responds to different amounts of surplus differently. The drastic increase of calories above this amount in an attempt to speed up the process will likely lead to increased fat accumulation.
If your goal is to maximize muscle growth without significant changes in body fat percentage, try starting at a more modest increase of 350-500kcal per day and if you aren’t seeing results after a few weeks, add an additional 100-200kcal/day for a couple weeks and reassess your progress then. Keep adjusting until you start seeing the results you are shooting for. Keep in mind that improvements in muscle are SLOW, even slower than changes in body fat, and require more patience especially for those with training history who have already surpassed their initial newbie gains. The addition of 1-5 pounds of muscle a month is great progress, especially for an experienced swoldier.
5.) Optimal Amounts of Protein
Along the same lines as the previous point, it is vital that we incorporate enough protein in our diets to optimize the rate of muscle protein accumulation. The amino acids from protein are the building blocks for creating new proteins and without adequate levels in our diet, we may inhibit growth. While our body can produce 11 of the 20 amino acids from other nutritional sources, there are 9 amino acids considered to be essential in that we must get them from our diet.
To ensure we are getting enough of each of these amino acids, we should aim to incorporate complete proteins, such as meat, diary, eggs, and seafood which contain all 20 amino acids.
If you are vegetarian/vegan, however, you can still get complete proteins in your diet through the incorporation of a variety of vegetables. While vegetables by themselves are considered incomplete proteins, the combination of two or more, such as in rice and beans, can create a complete protein.
In a review of protein needs for athletes, Phillips and Van Loon found a consensus that for optimal adaptation to exercise and maximal muscle protein synthesis, athletes should shoot for 1.3 – 1.8g protein/kg bodyweight/day32. The position stand of the International Society of Sports Nutrition recommends similar, but slightly higher amounts of protein intake at 1.4 – 2.0g protein/kg bodyweight/day31,33,34.
If you are new to tracking your nutrition, try starting at the lower end of these guidelines and work towards becoming consistent with them. Setting to high of a goal too soon can you to consistently miss your goal which can take a real toll on your motivation and cause you to give up. Instead, shoot for something you feel 95% confident you can hit every day and be consistent. When that becomes easy, raise your goal slightly.
If tracking macronutrients isn’t quite your cup of tea, Precision Nutrition offers a handy alternative of using your hand as a guide. Men should shoot for approximately 2 palm-sized servings of protein per meal and women should shoot for 1 palm-sized serving.
Now that we have discussed these five necessary components of muscle growth, how do we structure a program that would maximize the effects of all of these? Brad Schoenfeld has a great review article, on this subject that I definitely recommend you read on the first three points we mentioned3. Nutrition, however, also plays a key role in our ability to maximize muscle growth. In summary:
- To maximize the effects of muscular tension we need to utilize loads of at least 65% of our 1RM or higher.
- A rep scheme of 8-10 reps/set has been shown to be the most conducive towards muscle growth. This is because it allows for the greater amounts of time under tension necessary to produce muscular damage and metabolic stress while also allowing the use of weights 65% of 1RM or greater to stimulate significant enough levels of mechanical tension.
- Use rest periods of approximately 1-2 minutes. Much of your strength is recovered within about 1 min of rest35, however, rest periods shorter than this will hinder performance in following sets. Longer rest periods, however, may reduce metabolic stress.
- Shoot for a caloric surplus of around 350-500kcal to start. If you aren’t seeing progress in a few weeks, adapt that surplus as necessary to keep progress moving. Remember, muscle growth is a slow process and requires patience. Creating too great of a surplus in the attempts to gain muscle quicker will likely lead to significant amounts of added fat, without a much greater rate of protein synthesis. If you are patient, gains will come.
- Ensure adequate protein intake to provide the muscles with the building blocks to produce new muscle proteins. Research suggests that 1.2-2.0g of protein/kg body weight/day may be ideal for maximizing rates of protein synthesis.
Whatever your reason for embarking on your swoley quest, these five tenets should serve as faithful companions. Keep in mind, this is a LONG, SLOW journey. If you stay patient and consistent, however, the end is rewarding. I hope you all found this post helpful! As always, please feel free to leave comments or questions below and if you are looking for a coach to help guide you towards your goals, we would love to be that guide. Have a happy and healthy day!
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