Resistance Training Adaptations to Performance.docx

Resistance Training Adaptations to Performance ***.4.1: Resistance Training Promotes Changes in the Nervous System*** - Neural adaptations contribute to RT induced increases in muscular strength - Neural adaptations have a key role in strength gains in the early stages of training, ie...

Resistance Training Adaptations to Performance ***.4.1: Resistance Training Promotes Changes in the Nervous System*** - Neural adaptations contribute to RT induced increases in muscular strength - Neural adaptations have a key role in strength gains in the early stages of training, ie: 2-8 weeks. As time goes on, it becomes more physiological adaptations. - Untrained people will see increases in strength anyway between 10-80% in the first 6 months of training, but the initial gains are neurological adaptations. - Evidence supporting neural adaptations in the first 8 weeks is that muscular strength increases in the first 2 weeks without change to muscle fibre sizer and the cross education training of one limb results in increases in strength in the untrained limb. - The exact mechanisms that lead to increases in neural drive is unclear and inconclusive. - There is some evidence that RT lowers inhibition in the motor cortex and spinal cord. - Prior to training, we have a high contraction of the antagonist muscle. Max force production is achieved when the agonist muscle isn\'t paired with co activation of the antagonist, but literature is inconclusive on this concept.   *Neural Steps Leading to Muscular Contraction* 1. Process: muscular contraction begins \> higher brain centres 2. Neural message forwarded to motor cortex 3. Message is dispatched to brain steam and relayed to spinal cord 4. At the spinal cord, excitatory neural message depolarises motor neurons 5. Send waves of depolarisation down the axon to the muscle fibres contained in the motor unit.   *Neural Adaptations* Increased neural drive, this results in: - Increased number of motor units recruited - Increased firing rate - Increased synchronisation - Improved neural transmission across NMJ   ***4.2: Resistance Training Induced Changes in Muscle Structure and Function*** *RT promotes an increase in muscle fibre specific tension in type 1 fibres:* - Specific force production in muscle fibres is greater in type 2 than type 1 fibres. - Type 2 fibres have more myosin and cross bridges = greater force generation - Increases in muscle fibre specific tension in type 1 fibres is linked to increased calcium sensitivity = more cross bridges binding to actin. This is independent to changes in muscle size.   *Training induced increases in muscle mass:* - Hyperplasia: increase in a total number of fibres in the muscle, however, there is lack of evidence to support that this occurs in humans. There is a wee bit of evidence in animal models, but not much. - Hypertrophy: increased CSA of a muscle fibre. Dominant factor in RT changes in muscle mass. This is due to an increase in muscle proteins.   **Physiological Variable** **RT Effect** **Comments** ---------------------------------------- ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------- Nervous System Increased neural drive, possible changes in ratio of agonist/antagonist activation Adaptation occurs rapidly after initiation of training program Muscle Mass increased Hypertrophy detectable within 3 weeks after initiation of training. Unclear if hyperplasia occurs in humans Muscle Fibre Specific Force Production Increased Specific force increased in type 1 fibres only Muscle Fibre Type Shift from fast to slow fibres Small shift from type 2x to 2a with no evidence of % type 1 fibres increasing Muscle oxidative capacity unclear Increases in muscle oxidative capacity possible, but depends upon type of resistance training performed Muscle capillary density unclear Training adaptation possible, but depends upon type of training being performed Muscle antioxidant capacity increases 12 weeks of training increases antioxidant enzyme activity by almost 100% Tendons and ligament strength increased Harmonised increase in tendon/ligament strength to match increases in muscle strength Bone mineral content Increased Increased in bone mineral content results in stronger bones.   ***4.3: Detraining following Strength Training*** - Ceasing any RT program leads to a degree of atrophy and loss of strength. - Strength losses occur slower than endurance based adaptations. - Recovering strength loss can occur quite fast, within 6 weeks, of returning to training.   Does skeletal muscle have a memory? - Gym myths: after a prolonged period of no training, when you train again, you can make rapid gains during retraining. Supposed muscle memory. - This is a controversial topic. - Research suggests it is due to RT induced increases in myonuclei in the trained fibres that aren\'t lost during detraining. - Maintaining these myonuceli gives an edge in protein synthesis upon retraining.   Prolonged inactivity leads to rapid atrophy - 20-30 days of inactivity can lead to a 20-30% reduction in muscle fibre size - Conservation of muscle mass is dependent on balance between MPS and MPB - Increases in radial production promotes muscle atrophy