Neuromuscular exercise physiology combines the disciplines of neuroscience, muscle physiology and exercise physiology into one dynamic field of research. It promotes debate on innovative topics while offering new directions of investigation in this vibrant arena of study.
Positive neuromuscular adaptations increase task efficiency and decrease energy expenditure, protecting joints from excessive loads/motions, improving training/conditioning effectiveness and avoiding injury. Negative maladaptations on the other hand may increase energy expenditure or load, limit exercise/training effectiveness and ultimately cause fatigue and injury.
Neuromuscular exercise physiology Adelaide seeks to build motor neuron pathways that support brain-body coordination during functional movements and sport-specific training, ultimately increasing athletic performance while decreasing injury risks.
Neuromuscular Mechanisms of Exercise Adaptation
An athlete’s ability to generate maximal force through coordination of multiple muscle groups relies on a complex neuromuscular system that must be trained.
Long-term resistance training can bring about significant physiological (metabolic, histochemical), histochemical and neural adaptations; however, the exact mechanisms governing these changes remain obscure. Recent research suggests that molecules such as insulin-like growth factor, bassoon protein and neurotrophin 4 may play important roles in mediating training-induced adaptations at the NMJ.
Further studies have demonstrated that eccentric training provides a more potent stimulus for increasing strength than concentric exercise alone, with combined concentric and eccentric exercise increasing strength even more than either type alone. These findings further support the notion that different cellular processes contribute to various adaptations from exercise programs, emphasising their importance when including in workout programs.
This text bridges the fields of neuroscience, muscle physiology and exercise physiology to offer a comprehensive view of how nerves and muscles collaborate during acute and chronic exercise. Chapter objectives and review questions help readers navigate its content while special sidebars provide further analysis and practical applications – an excellent text for advanced undergraduate and graduate students studying exercise physiology or sports biomechanics.
Neuromuscular Fatigue and Recovery
As with physical exercise that is sufficiently strenuous, extended physical exercise may reduce our capacity to produce voluntary force – this condition is known as fatigue. When physical activity stops abruptly after cessation of activity, often central fatigue (impairments to excitation-contraction coupling and reperfusion) returns rapidly – in other instances however only part of central fatigue recovers at once while the remainder reflects peripheral contributions which may take a bit longer to heal themselves back up again.
This study investigated recovery kinetics from both central and peripheral fatigue in highly trained individuals following repeated maximal sprint exercises and low-intensity isometric knee extension exercises until exhaustion. Ten participants were required to sustain a target level of knee extensor isometric force until exhaustion during MSL (5 sets of 10 repetition maximum bilateral leg extensions) and ESL (1 set of 5 repetition maximum unilateral knee extensions), with isometric force-time curves and voluntary activation measured prior to and immediately following each test.
Results indicated that both central and peripheral fatigue contributed to impaired force generating capacity, with peripheral fatigue having a greater influence on MVC recovery and potentiated twitch force than central fatigue. Furthermore, magnitude of decline of both MVC and %VA during recovery depended on intensity/length of exercise; all indices except contraction time experienced gradual recovery within 10 s postexercise recovery.
Motor Unit Properties During Dynamic Movements
For muscles to move with precision or exert force, they require the activation of motor units supplied with control commands from the brain. A motoneuron innervating muscle fibers constitutes one motor unit. Weak motor neuron input causes only few units to activate, producing minimal force exerted by muscles (Play 1). Conversely, stronger input leads to more neurons being recruited, leading to greater force exerted from them (Play 2).
Each type of muscle fiber is innervated by different groups of motor neurons. Group Ia afferents fire during linear stretching to encode changes in length. Once stretched to its new length, these Ia afferents cease firing and the muscle becomes taut due to coactivation between alpha and gamma motor neurons; in particular gamma motor neurons create weak contractions within muscles that keeps spindles taut while signalling any length changes.