Physiological Adaptations through Strength Training

David Arcemant, BS, CSCS

When most people train and exercise, there are typical goals that are desired; that is, everyone wants to gain muscle, lose body fat, and become healthier versions of themselves. However, these goals should be viewed as superficial outcomes to what REALLY takes place when we strength train. Further, we should recognize that these goals are not met before our physiological responses due to the process of training. Rather, It is the consistency of physiological responses required in the demands of training that we ultimately achieve our goals. In simple terms, you can’t expect to lose weight, gain muscle, or enhance other outcomes BEFORE meeting the required adaptations to do so.

So what are the physiological adaptations that occur during the process of training?

1. Increased Cross Sectional Muscle Tissue

Anatomy of muscle tissue

The main purpose of skeletal muscle tissue is for locomotion; that is, it allows us to move our body and produce forces. When you train, you are thus requiring the skeletal muscle tissues to adapt and become denser for greater force production, and the greater your muscles can produce force, the greater your capacity is to achieve the overall outcome. In fact, here I describe how important strength training is regardless of your specific goal. Further, greater muscle density equates to better body composition and longevity in a higher quality of life. A lack of muscle tissue can lead to sarcopenia as we age, which thus correlates to certain chronic illnesses and a lower quality of life.

2. Increased Bone Density

A comparison of heathy bone mass versus Osteoporosis

Bone tissue is essential because it makes up our entire skeletal frame. This is also where tendons and ligaments attach to and where forces to the body end up. Therefore, it is important to have an increase of bone density in order to sustain forces applied to the body. Because of this, bone tissue reacts to strength training by resisting forces applies to the body and becoming thicker. The loss of bone can result in Osteoporosis and Osteopenia which reduces quality of life and can cause bone to fracture easier.

3. Increase Ligament Strength

Ligaments and tendons help create the structure of a joint, such as the knee

Ligaments are tissues around joints that connect bones to bones. When the joint is taken through a range of motion, certain ligaments will move and stretch while keeping integrity of the joint. When you strength train, the ligaments must keep the joints’ integrity against the forces acting upon it. Many times, ligaments are enhanced through muscles; for example, the Hamstrings help the Anterior Cruciate Ligament (ACL) around the knee joint. Therefore, this adaptation occurs in reaction to sustaining integrity of joints acted upon during strength training. Hyper-mobility and subluxation can result from essentially the loss of integrity of the joints resulted from lost ligament strength.

Acute stress on the body leads to chronic adaptations

4. Increased Immunity

When you train, acute stress is applied to the body. Adaptations respond to this stress and increases in immunity results. This includes your immune system much in the same way it occurs when you catch certain illnesses; when you are caught into a certain stressor, the body can mediate an immune response to it. However, when we train too often or too hard, we can decrease our immune system (i.e. getting run noses or feeling lethargic after workouts). This is why those that train or exercise frequently and consistently are often less sick than those who do not.

5. Increased Neuromuscular Efficiency

The nervous system works synchronous with muscle tissues to dictate proper movements

Skeletal muscles cannot react without a nerve impulsing it. This is known as a Motor Unit. Strength training increases the efficiency of nerve impulses into the skeletal muscle innervated. This occurs through rate of firing, in which the muscles are sequenced to contract at a certain rate, and recruitment, the amount of muscles that can act synchronously. This helps explain increasing strength without added muscle as well as coordination, balance, and speed.

6. Increased Cardiovascular Health

In lifting heavy, blood pressure acutely rises due to sustained contractions and intra-abdominal pressure. When this occurs, blood vessels micro rupture and the heart pushes harder for the blood to continue flowing properly. The effects of this acute stress is chronic adaptations of higher elasticity of the blood vessels and a thicker wall in the heart, thus increasing stroke volume and decreasing resting heart rate. This in turn helps to create a stronger cardiovascular system and can aid in lowering blood pressure and preventing heart disease.

7. Increased Nutrition Partitioning

Nutrition partitioning is a big factor of where calories end up

When we eat certain foods, the nutrients are absorbed and utilized into the body in different ways. Further, certain foods may be prioritized in accordance to what the body requires. For example, when we eat a Carbohydrates, this nutrient breaks down into Glucose that then enters the blood stream. Depending on the requirements of the various tissues, the Glucose either enters the liver, muscle cells, or adipose tissue (Fat storage). Through training adaptations, the body requires a higher storage of Glucose to be stored into muscle cells, which therefore enhances its effect on body composition from nutrition partitioning. In essence, strength training helps prioritize where nutrition is utilized in the body.

8. Increased Hormone Sensitivity

Hormones are only as useful as when the cells are receptive to them. Therefore, there can be an infinite amount in the body, but if the cells do not utilize them, they are not effective. Likewise, a finite of hormones in the body may be exactly enough for the cells that are receptive to them. For example, Insulin is secreted through the Pancreas and is used to regulate Glucose in the blood stream by storing it into the liver, muscles, and fat tissue (as stated in a previous example). Type II Diabetes is the result of these tissues becoming insensitive to Insulin, thus resulting in a spike of Glucose left into the blood stream. In strength training, adaptations result in cells becoming sensitive to these regulatory hormones in an effort to properly recover from the stress of workouts imposed upon them. Testosterone is another great example. Instead of thinking about the amount you have in the body, think about the sensitivity of the receptors instead. When becoming stronger, the cells become more sensitive and receptive to Testosterone in an effort to adapt to the acute spike of Cortisol placed due to the added stress. When cells become more adaptive to Hormones, they become more efficient.

It is with these Physiological adaptations that goals and outcomes can be met. In meeting the framework towards your fitness endeavors can you achieve your strongest and healthiest self!


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