Introduction
Skeletal muscle is tissue your body uses to move around, generate force, store glycogen, and so much more. Due to its complexity and various tasks, many types of adaptation can occur. In this article, we will explain what muscle is composed of, the adaptations it can undergo, and how we can achieve specific adaptations for our specific goals.
Components of muscular tissue
Muscles are composed of several things, but the main structure is fascicles, which are just bundles of muscle fibers. In more deeper intracellular perspective of muscle, these are the components: Myofibrils are what actually produce force through contraction. Composed of lines of sections named sarcomeres, which each contain myofilaments, those being Actin and Myosin. Think of myosin as the rope that connects to actin to pull. Sarcoplasm is the fluid component of muscle tissue which contains several things to support muscle function. Starting with the myoglobin protein responsible for bringing in oxygen to fuel muscle tissue. We also have Glycosomes, glycogen granules that provide immediate energy to muscle cells. Additionally, we have mitochondria that use oxygen carried in from myoglobin and glycogen to produce massive amounts of energy through aerobic respiration. The sarcoplasm fluid also contains potassium, phosphate, magnesium, other electrolytes, and enzymes for the conducting of electrical signals and chemical reactions needed to carry the muscle’s functions.
[!INSIGHT]
What maintains Muscle? Muscle is very metabolically expensive, so the body needs a compelling reason to keep it, or it will be broken down for energy and/or to conserve energy. During the day, your body breaks down muscle and also synthesizes it. Muscle maintenance comes down to balancing muscle protein synthesis and breakdown.
Mechanics of muscle tissue
Motor units
Functional units of the neuromuscular system are motor units, which consist of a motor neuron and the fibers it controls. These follow a ‘size’ rule where the smaller slow twitch motor units are recruited first before the larger more powerful fast twitch units.
Molecular drivers
The body translates mechanical force, stretch, and much more into chemical signals. Muscle cells use costameres, focal adhesion kinase and more to activate specific pathways like mTORC1 and HIPPO to adapt.
Hormonal environment
There are several messages that tell your body to build or break down muscle tissue. Anabolic hormones tell your body to preserve tissue and send nutrients into the muscle. Catabolic hormones tell your body to break down tissue for energy. Though in this article, we will mainly focus on muscular adaptations.
Muscle Protein Synthesis
Before delving into muscular adaptations, it’s important to understand muscle protein synthesis and how it is different from other forms of growth. Muscle protein synthesis is the process by which skeletal muscle proteins are repaired and built. Muscle protein synthesis occurs when a stimulus is provided, such as adequate protein intake to provide essential amino acids and resistance training.
Science of muscle adaptations
Hypertrophy
Muscle fibers can undergo different structural adaptations in size in response to different stimuli.
- sarcoplasmic hypertrophy: this is an increase in the size of the sarcoplasm. Main adaptation for high volume, where the muscle is starved of oxygen and or glycogen, and short rest periods. The sarcoplasm is increased to meet long-term energy demands and withstand high stress.
- myofibril packing. The addition of myofibrils makes the muscle significantly more dense. Main adaptation for heavy load is where muscle fibers are recruited to generate high amounts of force. This adaptation is triggered by the recruitment of fast-twitch units, which provide the greatest stimulus for myofibril addition.
- Proportional myofibular hypertrophy: This is a combination of the addition of myofibrils and an increase in the sarcoplasm.
[!IMPORTANT]
We discussed muscle protein synthesis before discussing these adaptations. The addition of myofibrils is a subprocess of muscle protein synthesis, but once it stops, the rest of MPS repairs, and other proteins are synthesized for different adaptations. Keep this in mind for the practical application section.
Neuromuscular adaptations
As mentioned earlier, motor neurons control muscle fibers. Neuromuscular adaptations occur to better recruit motor units. For example, an untrained lifter can only consciously recruit a portion of their available units for maximal effort, but an elite lifter who has a better-adapted nervous system can activate nearly all of their motor units. These adaptations are:
Better Rate coding: Rate coding is the speed of electrical signals that travel from the brain, through the spine, to the muscle. Slow signals make the muscle twitch and relax. Fast signals cause the muscle to twitch before it has time to relax, resulting in a forceful maximal contraction. Synchronization of Motor Units: This adaptation involves recruiting motor units simultaneously. Think of having five people pull a rope. If one person pulls at a time, not much force is generated, but if all five pull at the same time, you create a significant force. Less Antagonist activation: This adaptation involved the decrease in activation of a muscle doing the opposite of the one in use. Think of biceps and triceps; one extends the elbow, the other flexes it. In a newbie, when they train their biceps, their triceps may be activating, making them fight against themselves, but in an advanced lifter, when training biceps, their triceps have little to no activation, allowing for better force output. Golgi Tendon Organ Tolerance: The Golgi Tendon Organ is a safety sensor located at the meeting point of your muscle and tendon. If your GTO senses that there's enough tension that could potentially tear the muscle, it shuts your muscle down even if you consciously wish to keep pushing. Consistent heavy training gradually adapts your GTO, learning that the tension is safe, allowing you to proceed with recruiting units.
Other Muscular Adaptations
Tendon stiffness: Heavy loading may cause tendon stiffness in certain exercises like plyometrics, optimizing stretch stretch-shortening cycle.
[!IMPORTANT]
THE FIBER TYPE CHANGE HAS LIMITED RESEARCH
Fiber type change: Some research suggests that some fibers can transition to different fiber types. For example, resistance training may cause type IIx fibers to convert to type IIa fibers. Mitochondrial/aerobic changes: Endurance stress drives mitochondrial biogenesis, capillary formation, and efficient restructuring of mitochondrial folds. research:
Practical applications
Muscular adaptations:
Overall Health: do a combination of hypertrophy, endurance, strength, stretch, and more. These will help you stay healthy and prevent injury long-term.
[!IMPORTANT]
It is important to note that intense endurance training can blunt muscular adaptations from AMPK signals that inhibit mTORC1 pathways. To avoid this, try to spread out your weight training from your endurance training to allow adaptations and recovery to continue.
Endurance training: Train at moderate intensity for long periods with adequate rest. The goal is to create a stimulus for better energy efficiency without causing excessive stress that could lead to injury or the breakdown of muscle tissue.
Hypertrophy: Growth requires a good amount of volume, frequency, and intensity. Aim to spread your sets throughout the week to allow for recovery and for stimulus to grow. Aim for high intensity during those sets to produce adequate stimulus and other adaptations for general health.
Strength: Train with high intensity and great rest. The goal is to recruit as many fibers as possible, efficiently. This is a result of Myofibular hypertrophy and neuromuscular adaptations.
! Like discussed earlier, Myofibular additions to the muscle are a sub-process for Muscle Protein Synthesis. That is why doing excessive volume won't equate to more growth. Once the stimulus for myofibular additions end, if the muscle is still fatigued, there cannot be more stimulus, for you cannot recruit the muscle fibers needed to stimulate hypertrophy, and you are at risk of injury. This is why spreading volume, keeping intensity high, and optimizing recovery are best for myofibular growth.
Nutrition and Sleep:
Nutrition is essential to preserve muscle tissue. Adequate protein is required for Muscle protein synthesis and myofibrillar protein synthesis. Enough micronutrition for effective recovery in joint health, cardiovascular, and much more. Proper sleep for hormonal regulation, Central Nervous System recovery, and overall health. Additionally, contrary to popular belief, Carbohydrates are equally as important as protein for growth, since they optimize recovery (especially neuromuscular) and provide the proper fuel to create the stimulus needed for adaptations.
Using Graviflux to help you reach your Goals
Graviflux offers a variety of tools to help you reach your goals for completely free. We strongly believe in not focusing on only one aspect of health but on all forms.
Workout: Using the workouts tab, track your lifts, endurance, frequency, and more. Use advanced tracking metrics like Reps In Reserve and Rate of Perceived Exertion to help adjust accordingly for recovery and gauge your next exercise session. Remember to look at the weight and reps you did in previous sessions for an exercise using the ‘eye’ symbol. This will help you know what weight you should be using and increase to continue to create the stimulus needed for adaptation.
Nutrition: In the nutrition tab, log your meals and use the ‘Nutrition overview’ button to see all your Macros, vitamins, minerals, EAAs, and more, ensuring you are eating enough in all areas of nutrition. Note! Some foods may not contain all food data due to limited research
Wellness: The wellness tab is incredibly useful for viewing progress over time. In the trackers section, you can track anything, use progress photos to keep track, and view your hard work. Use meditation and journaling to take care of your mental health. This will help you stay motivated to reach your goals.
Social: Ask questions, share progress, offer advice, and more by speaking with others.
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