Final answer:
Pulse durations for muscle contractions in innervated muscle vary, but for neurological stimulation, it's typically between 200 to 400 microseconds. The cardiac muscle has much longer refractory periods necessary for effective blood pumping.
Step-by-step explanation:
When producing a muscle contraction in an innervated muscle, the pulse duration should typically range between several hundred to a few thousand microseconds. However, the exact duration can vary based on the intended use (therapeutic, exercise, etc.), the type of muscle fiber being stimulated, and the type of equipment used.
For proper heart function, it is important to note that the cardiac contractile muscle has an absolute refractory period of approximately 200 ms (200,000 microseconds) and a relative refractory period lasting approximately 50 ms (50,000 microseconds). While this refractory period is significantly longer than what might be used for skeletal muscle stimulation, it highlights the importance of carefully controlled durations to ensure effective and safe muscle contractions.
In the context of exercising skeletal muscles using electrical stimulation, literature suggests various ranges for pulse duration. As an example, it's not uncommon to use pulse durations between 200 to 400 microseconds for neuromuscular electrical stimulation (NMES). Yet, the specifics of pulse duration for stimulating contraction can vary and should be sourced from medical or exercise physiology guidelines for accurate and safe practice.