Most of you have read about the benefits of resistance training and probably have – or intend to – incorporate some form of it into your routine. The research is quite conclusive in support of daily, weight bearing exercise as a means of overcoming many of the degenerative effects of aging, the prevention of certain diseases, and even enhancing neural and cognitive function.
I want to dig a little deeper now and reveal a complete and comprehensive list of the long term (chronic) physiological adaptations that occur as a consequence of a well executed, progressive resistance training program.
I’ve listed the types of adaptations (ie. muscle performance) and a detailed breakdown of what up to date research has shown us about each. It might be a little “sciency” for some but I’ve done my best to make it accessible to most.
Muscle Performance Adaptations
- ↑ Strength
- ↑ Endurance
- ↑ Power
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Muscle Size & Structure Adaptations
- ↑ Muscle size (Cross Sectional Area (CSA) and volume)
- ↑ Muscle fiber CSA
- ↑ * Myofibril protein content
- ↓ * Myofibril protein degradation
- ↑ Conversion of * FOG to * FG muscle fibers
- The net result of these adaptions are increased muscular force and production capability.
[notification style=”tip” font_size=”12px”] * Myofibrils are composed of protein filaments and are contained within a muscle fiber. These filaments represent the site where muscle contraction initiates. [/notification]
[notification style=”tip” font_size=”12px”]* FOG – fast oxidative-glycolytic fibers. The human body is composed mainly of this fiber type.
* FG – fast glycolytic fibers. These muscles are called upon during explosive and power movements. [/notification]
Connective Tissue Changes
- ↑ Collagen Synthesis in tendons.
- Has been shown in some studies to increase tendon cross sectional area.
- ↑ Collagen Stiffness in tendons.
[notification style=”tip” font_size=”12px”] Collagen is the main component of connective tissue found throughout the body including tendon, ligament , cartilage, fascia, bone and skin. [/notification]
Skeletal Changes
- ↑ Bone Density – depends largely on the type and intensity of the resistance training program.
- ↓ Risk for osteoporosis, fractures, and falls in later life
Neural Adaptations
- ↑ Motor Unit Recruitment
- Untrained individuals are generally unable to recruit all available motor units.
- More Motor Units = Greater force production
- ↑ Synchonization of Motor Units
- Results in higher total muscle force as compared to asynchronous firing.
- ↑ Motor Unit Firing Rate
- Equals greater muscular force production.
- ↓ Golgi Tendon Organ (GTO) Reflex
- The GTO has been shown to be a likely inhibitor of muscle activation during intense muscular contractions.
- Less GTO response = Greater force production
[notification style=”tip” font_size=”12px”] A motor unit consists a single motor neuron and all the fibers it innervates. When a motor unit is activated, all of its associated fibers contract. Groups of motor units often work together to coordinate the contractions of a single muscle. [/notification]
Metabolic Adaptations
- ↑ Glycogen Storage
- Glycogen is an energy reserve that can be quickly mobilized to meet a sudden need for glucose.
- Without adequate storage, glycogen can become depleted after long bouts of exercise resulting in extreme fatigue for the individual.
- ↑ Insulin Sensitivity
- You will require lower levels of insulin to process glucose. Low levels of circulating insulin is associated with increased longevity.
- ↑ Phosphocreatine Storage
- The body’s best source of rapidly available energy. Your storage levels indicate how quickly you can recover from intense exercise.
- Greater storage = better recovery from intense muscle contractions.
- ↑ Creatine Phosphokinase (CPK)
- An important enzyme that, in higher quantities, increases the production of Phosphocreatine.
- ↑ Basal Metabolic Rate (BMR)
- BMR = the amount of energy expended daily at rest
- More energy expended at rest = better weight management for some and the need to eat more food for others.
Hormonal Adaptations
- Inconsistent findings on chronic elevations of Testosterone
- Inconsistent findings on chronic elevations of Cortisol
- No change in GH
- It appears that resistance training does not change resting growth hormone concentration
- ↑ in Insulin-like Growth Factor (IGF 1)
- IGF1 stimulates growth-promoting effects on almost every cell in the body.
Other Adaptations
- Serum Lipids
- ↑ in HDL Cholesterol (or remains the same)
- ↓ in LDL Cholesterol (or remains the same)
- Resting Blood Pressure
- Systolic Blood Pressure remains the same
- ↓ Diastolic Blood Presure (or remains the same)
- Body Composition
- ↓ Body Fat%
- ↑ in Lean Muscle
It should be apparent to you now that the benefits of resistance training go well above and beyond what is typically in the mind of the average trainee, and I’ve only covered the chronic physiological benefits of weight training. This does not include the acute adaptations you aquire during or right after an exercise session. Nor did I get into the mental, psychological and social benefits that regular exercise delivers.
In fact, I can’t think of one single activity that delivers more bang for your buck than weight training, when performed correctly. Yeah, it’s hard work but aren’t these desirable outcomes for all of us ?
Craig Simms
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