Acute and Chronic Adaptations - Strength Training Flashcards
Relation between force and cross sectional area of the muscle
The larger the cross sectional area of a muscle, the larger the force developed by the muscle.
Hypertrophy - Definition
Increase in the volume of muscle fibers.
More important than hyperplasia and more of hypertrophy than hyperplasia.
Hyperplasia - Definition
Increase in the number of muscle fibers. Fusion of muscle fibers with embryonary cells and/or fusion of embryonary cells together.
Hypertrophy - What needs to be done in order for it to work?
Increasing hypertrophy only works if you keep increasing the work load.
Repetition of training is needed.
When is hypertrophy visible?
after 4-6 weeks.
But proteins synthesis starts early after strength training.
Adaptations in muscle fibers (fast vs slow)(during training vs post training)
Increase in Fast (FT) and Slow (ST) fibers are similar. But the decrease post training is greater in Fast (FT) fibers.
Adaptations with concentric and eccentric training - Muscle volume
Eccentric training is more efficient in increasing the nr. of fibers, especially fast (type II) fibers.
Adaptations with concentric and eccentric training - Muscle force
Decrease in force after eccentric training at first, but strength increases after with greater level.
Increase in force after concentric training but plateau quickly.
Changes in Pennation Angle
Increase in pennation angle with muscle hypertrophy.
Fibers more oblique in order to increase the volume of muscle fiber.
If angle > 45° the force vector decreases and muscle gets bigger but do not develop more force.
Strength training and MUs
Increase in maximal strength in both young and old adults.
Increase in MU discharge rate.
Increase in muscle force explained by increase in MU discharge rate.
Strength Training and MUs - Neural Adaptations
Greater nr. of MUs recruited.
Increase in MU discharge rate.
Crossed Adaptation
Training one muscle group induces and increase in force in the contralateral leg. Up to 10-20% change in muscle strength.
Evolution of strength during strength training
Rapid increase of strength in beginning (mainly due to neural adaptations) and then plateau.
Hypertrophy starts later to contribute.
Both neural and muscular adaptations contribute to increasing force.
Relationship between H-reflex and Training
Increase in H-reflex after training.
Increase in MN excitability because of increase in MU recruitment.
Allows subject to take increased advantage of excitatory Ia inflow.
What Mechanisms are responsible for the increase in H-reflex post training?
At supraspinal and spinal levels.
Enhancing drive from descending pathways.
Decrease in presynaptic inhibition.
Recurrent inhibition.
Reciprocal inhibition.
Maybe golgi tendon organ.
