Training effect
Physical activity relies on muscular force. Our skeletal muscles are made of fibres with several types having different properties. Single muscle cells or myofibres can adapt to functional demand by increasing their metabolic capacity, becoming thicker or longer, and to some extent by a change in fibre type can occur in a muscle.
Adaptation is specific to the types or modes of exercise – aerobic and endurance exercise and strength training can both use the same muscles, but in different ways.
Classically exercises can be described by the load (light or heavy); number of repetitions and sets (high reps and sets for endurance, lower for strength and hypertrophy); rest intervals in-between sets (usually longer when using heavy weights); training period (also called training “volume&rdquo
; and the frequency or number of times a week. Some of this is captured in the acronym FITTA – for frequency, intensity, time, type, and adherence.
Also important are the range of motion and the speed of contraction per repetition (changing the power required and the “time under tension&rdquo. The range of motion may be varied (or may be limited by equipment) and the speed may be varied, for example quicker or slower when lifting or lowering the weight.
It’s done by switching gene expression on or off.
The process of exercise-induced changes in muscle involves initiating replication of specific DNA genetic sequences, subsequent translation of the genetic message, and generation of amino acids that form new muscle protein.
Figure 5 from Review Article: Phenotypic Plasticity in Skeletal Muscle, Flück M., J Exp Biol. 2006 Jun;209(Pt 12):2239-48.
This is a schematic of the training effect showing an increase in mitochondrial RNA and endurance performance. Reference: Flück M. © 2006 The Company of Biologists 2006
Each session of endurance exercise leads to an overshoot of transcript level in the recovery phase. This leads to a gradual increase in mitochondrial density and improved oxidative capacity.
A similar concept applies to power training when anaerobic energy systems predominate, and to strength training, in which successive training with recovery intervals leads to progressive gains in strength thorough remodelling of muscle fibres.
References
Eur J Appl Physiol. 2006 Aug;97(6):643-63.
New fundamental resistance exercise determinants of molecular and cellular muscle adaptations. Toigo M, Boutellier U.
J Exp Biol. 2006 Jun;209(Pt 12):2239-48.
Review Article: Phenotypic Plasticity in Skeletal Muscle
Functional, structural and molecular plasticity of mammalian skeletal muscle in response to exercise stimuli. Flück M.
- Prolonged endurance training results in more mitochondria being made in muscle cells (mitochondria are effectively the “power” plant of the cell); transformation from fast-to-slow fibre-type; and a switch in substrate metabolism (more efficiently using fat rather than glucose at any exercise intensity).
- By contrast, heavy resistance stimulates synthesis of contractile proteins responsible for muscle hypertrophy (bulking-up) and increase in maximal contractile force or power output.
Classically exercises can be described by the load (light or heavy); number of repetitions and sets (high reps and sets for endurance, lower for strength and hypertrophy); rest intervals in-between sets (usually longer when using heavy weights); training period (also called training “volume&rdquo
; and the frequency or number of times a week. Some of this is captured in the acronym FITTA – for frequency, intensity, time, type, and adherence.Also important are the range of motion and the speed of contraction per repetition (changing the power required and the “time under tension&rdquo
. The range of motion may be varied (or may be limited by equipment) and the speed may be varied, for example quicker or slower when lifting or lowering the weight. - Slow movements with heavy weights invoke a different response (muscle strength and size) than rapid movements with lighter weights (power, anaerobic), or prolonged movements with light weights (endurance, aerobic).
- A progressive increase in challenge and use of various exercises that place different demands on our bodies are both important to continue to make gains.
- The recruitment of other muscles can be altered by using for example free weights rather than machines or by doing the exercise on a balance disk, BOSU, or stability (Swiss) ball.
It’s done by switching gene expression on or off.
The process of exercise-induced changes in muscle involves initiating replication of specific DNA genetic sequences, subsequent translation of the genetic message, and generation of amino acids that form new muscle protein.
Figure 5 from Review Article: Phenotypic Plasticity in Skeletal Muscle, Flück M., J Exp Biol. 2006 Jun;209(Pt 12):2239-48.
This is a schematic of the training effect showing an increase in mitochondrial RNA and endurance performance. Reference: Flück M. © 2006 The Company of Biologists 2006
Each session of endurance exercise leads to an overshoot of transcript level in the recovery phase. This leads to a gradual increase in mitochondrial density and improved oxidative capacity.
A similar concept applies to power training when anaerobic energy systems predominate, and to strength training, in which successive training with recovery intervals leads to progressive gains in strength thorough remodelling of muscle fibres.
References
Eur J Appl Physiol. 2006 Aug;97(6):643-63.
New fundamental resistance exercise determinants of molecular and cellular muscle adaptations. Toigo M, Boutellier U.
J Exp Biol. 2006 Jun;209(Pt 12):2239-48.
Review Article: Phenotypic Plasticity in Skeletal Muscle
Functional, structural and molecular plasticity of mammalian skeletal muscle in response to exercise stimuli. Flück M.
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