Finally, motor neurons (muptipolar neurons with many dendrites and a single axon) carry nerve impulses from the central nervous system to the muscles, and cause them to contract.
The fast rate of activation in this experiment is the result of training with the fast foot drill exercise. After approximately 16 weeks of deliberate practice to increase the rate of stepping during training, the author had increased the step rate from 4 to 7.5 per second for each leg. It could not be ascertained whether this improvement to stepping rate was facilitated by reduced vertical elevation of the foot with each step or through reduced ground contact time. Also the deliberate practice included a progression in adding external resistance which may have aided in reducing vertical elevation. In the absence of studies on movement speed of human legs, a study of movement speed of hands showed the world’s fastest drummer to have a tapping rate of 10 Hz with each hand; a rate gained from deliberate practice to improve tapping rate (29). In comparison, ordinary drummers and non-drummers had mean tapping rates of 6.6 Hz. From the study of drummers and with regards to the worlds fastest drummer it could be inferred that deliberate practice to execute the fast foot drill faster in human locomotive muscles may lead to faster step rates and shorter muscle activation times than recorded here. In order to have any relevance to athletic sport any future re-search in this area needs to quantify the level of muscle recruitment as a percentage of maximum voluntary contraction and rate of force production.
Regulation of a Smooth Muscle Contraction: A Hypothesis Based …
Researchers say that forward movement can only be achieved with horizontal propulsion (7,8). Data at speeds of 9.59 and 9.96 m/s show that sprinters produce around 338 and 312 N of horizontal force respectively (9, 10); there is an absence of horizontal force data from higher speeds of running especially from the fastest humans although the trend suggests that horizontal force per unit of bodyweight increases with velocity (6). However given that movement of the legs are the functional result of activating muscles (11) and knowing that even athletes with a preponderance of fast-twitch fiber produce less force at faster velocities of contraction (12), humans may struggle to produce enough horizontal force to reach 70 kph as air resistance increases and as ground contact time shortens even more.
Skeletal muscle->is ideally at the top of ..
The hypothesis regarding GLUT 4 being tested in this research article stems from related research, which showed that GLUT 4 and mitochondria increase due to repeated bouts of muscle contraction....
Florida State College at Jacksonville
A logical explanation for sprinters having greater type II than type I fiber areas in their leg extensor muscles, and therefore being faster, is that their training consists of fast repetitive movements (10). Researchers have found that a greater percentage of fast-twitch fiber in the legs correlates with faster sprint performance (20,21). Sprint running involves stride rates of 4–5 steps per second (10) or 2–2.5 steps per second (and implied muscle contraction rates) for each leg. Quicker activation times may have been present in sprint cycling of up to 200 rpm or approximately 3.33 contractions per second per leg but no change was found in minimum muscle contractile times from training at that rate (18). Perhaps we could influence minimum contraction times with even quicker frequencies of movement. One sprint training exercise that may provide an avenue to achieving this is the fast foot drill consisting of fast repetitive movements of stepping usually over a confined distance (22). Such an exercise practiced by track athletes over 12 months has improved fast foot drill stepping rates per leg from 4.5 to 6 steps per second (personal correspondence). The hypothesis herein is that the fast foot drill may produce shorter muscle contraction times; it is not intended to imply an increase in stride rate. Furthermore, these short muscle contraction times must be supplemented with strength training during the exercise to increase force production within these small time constraints; through biological adaptation. To my knowledge no study has observed the rate of stepping or the time of muscle activation in such an exercise.