INTRODUCTION:
An individual’s level of strength is not only dependent upon on the muscles involved in an action but also the nervous systems ability to activate the appropriate muscles at any one time. It is well known that resistance training can lead to an increase in maximal contractile muscle force (Aagaard et al., 2002) however; this adaptation is not primarily explained by an increase in muscle volume or muscle cross-sectional area but adaptive changes within the nervous system. Electromyography (EMG) studies have provided the most direct evidence (Sale, 1988). EMG measures the electrical activity of muscles during rest and during contraction. It is produced by the weighted summation of activity of many motor units with different contractile properties (Peterson, 2009). The possible mechanisms of neural adaptations are discussed in relation to motor unit recruitment and firing patterns, cortical plasticity, change in agonist activation and changes at the spinal level.
CORTICAL PLASTICITY …show more content…
After four weeks of resistance training on the tibialis anterior muscles, there was found to be significant increases in MEP amplitude during low force contractions. This corresponded to an increase in surface EMG with no significant change in the maximal M-wave (Griffin and Cafarelli, 2003). After two and four weeks of resistance training, the increase in MEP amplitude was significantly higher compared to baseline. Maximal force output can also be identified as it was found to progressively increase from the initial stages of training but the MEP amplitudes were no higher in week four than they were in week two. Further study is needed to determine the time frame of increases in cortical excitability in relation to increases in maximal force during resistance
An individual’s level of strength is not only dependent upon on the muscles involved in an action but also the nervous systems ability to activate the appropriate muscles at any one time. It is well known that resistance training can lead to an increase in maximal contractile muscle force (Aagaard et al., 2002) however; this adaptation is not primarily explained by an increase in muscle volume or muscle cross-sectional area but adaptive changes within the nervous system. Electromyography (EMG) studies have provided the most direct evidence (Sale, 1988). EMG measures the electrical activity of muscles during rest and during contraction. It is produced by the weighted summation of activity of many motor units with different contractile properties (Peterson, 2009). The possible mechanisms of neural adaptations are discussed in relation to motor unit recruitment and firing patterns, cortical plasticity, change in agonist activation and changes at the spinal level.
CORTICAL PLASTICITY …show more content…
After four weeks of resistance training on the tibialis anterior muscles, there was found to be significant increases in MEP amplitude during low force contractions. This corresponded to an increase in surface EMG with no significant change in the maximal M-wave (Griffin and Cafarelli, 2003). After two and four weeks of resistance training, the increase in MEP amplitude was significantly higher compared to baseline. Maximal force output can also be identified as it was found to progressively increase from the initial stages of training but the MEP amplitudes were no higher in week four than they were in week two. Further study is needed to determine the time frame of increases in cortical excitability in relation to increases in maximal force during resistance