MUSCLE RESPONSES TO TRAINING
MUSCLE RESPONSES TO TRAINING
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| Muscle Training |
HOW DO MUSCLES RESPOND TO TRAINING ?
Exercise training induces an increase of oxidative capacity, fiber type changes, and elevated GLUT4 protein levels in skeletal muscle; adaptations which are of critical importance to lower free fatty acids, improve glucose uptake, and decrease the risk of insulin resistance and diabetes.
WHAT ARE THE 4 MAIN MUSCLE RESPONSES TO TRAINING ?
When muscles undergo a period of training their enzyme activity and structure become modified in response to the training. This is known as adaptation.
MUSCLE FIBER TYPE :
There are essentially three types of muscle fibers, i.e.
- slow oxidative
(SO or type I)
- fast glycolytic
(FG or type IIx)
- fast oxidative-glycolytic (FOG or type IIa).
These respond to training, although the magnitude of the response for each fiber type depends on the training.
EHDURANCE TRAINING :
This type of training promotes the aerobic development of muscle fibers and is usually prolonged exercise undertaken at a relatively low exercise intensity. It may be continuous or intermittent.
SPRINT TRAINING :
This form of training enhances the anaerobic capacity and power generative capacity of muscles. Sprint training normally involves repeated efforts at a high exercise intensity.
1- ADAPTATION :
Adaptation occurs in muscles as a consequence of repeated bouts of exercise over a period of time. The form of adaptation can be structural, in which case there is a modification of the actin and myosin, or functional, in which changes occur with respect to mitochondrial density and cytoplasmic enzyme activity.
1- ADAPTATION :
Adaptation occurs in muscles as a consequence of repeated bouts of exercise over a period of time. The form of adaptation can be structural, in which case there is a modification of the actin and myosin, or functional, in which changes occur with respect to mitochondrial density and cytoplasmic enzyme activity.
2- MUSCLE FIBER TYPE :
Muscle fiber type Muscle fibers generate the power and energy for work to be undertaken and are essentially of three types based on their contractile and metabolic properties.
The SO fibers contain many mitochondria and have a high capillary network supplying blood to them. The net result is that they are the muscle fibers engaged in prolonged, lower levels of exercise. On the other hand, the FG fibers have fewer mitochondria and capillaries supplying blood, and consequently are the fibers employed in generating high levels of force.
3- ENDURANCE TRAINING :
Endurance training is that type of training in which the muscle fibers are recruited at lower levels of exercise intensity for a prolonged period of time . The energy demands for this type of activity are derived mainly from aerobic sources and are likely to tax the SO and FOG fibers rather than the FG fibers. Consequently the adaptations that occur do so in these muscle fibers.
The resulting changes are an improved ability to utilize oxygen due to increases in capillarization of the muscle fibers as well as increases in the number of mitochondria in the cells. Since the mitochondria contain the enzymes for the TCA cycle and for β oxidation of fatty acids, there is an improvement in aerobic capacity. The net result of endurance training can be measured in increases in VO2max, a shift in the lactate threshold to the right, and faster time to undertake a set distance.
4- SPRINT TRAINING :
Sprint training involves repeated bouts of high-intensity efforts interspersed with appropriate recovery periods Since the bouts of activity are intense, the FG and FOG fibers are mainly recruited to generate the force.
Muscle fiber type Muscle fibers generate the power and energy for work to be undertaken and are essentially of three types based on their contractile and metabolic properties.
The SO fibers contain many mitochondria and have a high capillary network supplying blood to them. The net result is that they are the muscle fibers engaged in prolonged, lower levels of exercise. On the other hand, the FG fibers have fewer mitochondria and capillaries supplying blood, and consequently are the fibers employed in generating high levels of force.
3- ENDURANCE TRAINING :
Endurance training is that type of training in which the muscle fibers are recruited at lower levels of exercise intensity for a prolonged period of time . The energy demands for this type of activity are derived mainly from aerobic sources and are likely to tax the SO and FOG fibers rather than the FG fibers. Consequently the adaptations that occur do so in these muscle fibers.
The resulting changes are an improved ability to utilize oxygen due to increases in capillarization of the muscle fibers as well as increases in the number of mitochondria in the cells. Since the mitochondria contain the enzymes for the TCA cycle and for β oxidation of fatty acids, there is an improvement in aerobic capacity. The net result of endurance training can be measured in increases in VO2max, a shift in the lactate threshold to the right, and faster time to undertake a set distance.
4- SPRINT TRAINING :
Sprint training involves repeated bouts of high-intensity efforts interspersed with appropriate recovery periods Since the bouts of activity are intense, the FG and FOG fibers are mainly recruited to generate the force.
The type of energy source used for each sprint bout is dependent on the time
i.e. 6 s or 45 s or 60 s intervals. The resultant effect is that the enzyme activity for that energy source is enhanced with training, i.e. repeat 5 s bouts are more
likely to enhance the PCr system whereas repeat 30 s bouts are likely to promote improvements in the glycolytic energy system. Changes can thus be seen in the enzyme activities of creatine kinase, glycogen phosphorylase, and PFK in the FG and FOG fibers.
likely to enhance the PCr system whereas repeat 30 s bouts are likely to promote improvements in the glycolytic energy system. Changes can thus be seen in the enzyme activities of creatine kinase, glycogen phosphorylase, and PFK in the FG and FOG fibers.
