Behavior of muscle-tendon complex(MTC)in stretch-shortening cycle(SSC)have been extensively studied in natural human movements.The purpose of this paper was to review the biomechanical investigations on SSC, especially in vertical jumping.An effective SSC requires three fundamental conditions:a well-timed preactivation of the muscles before touch-down, a short and fast eccentric phase, an immediate transition(short delay)between stretch(eccentric)and shortening(concentric phase).By the preactivation and the stretch-reflex in eccentric phase during take-off, the stiffness of the agonist's MTCs increased.This high level of the stiffness induced the post-tetanic potentiation of contractile component and the well elongation of elastic component in MTC.As a result, the MTC enhanced force output in concentric phase during take-off.The viscoelastic properties of MTC have been examined by the quick release, the vibration, the alpha, and the null-point methods in an animal isolated muscle, and by the quick release, the impulse response, and the ultrasound methods in human, respectively.By using these coefficients, the MTC in human jumping was modeled and simulated.The influences of the elasticity and the mechanical energy flow by two-joint muscle were quantitatively determined in these simulation studies.Furthermore, the SSC was studied from viewpoints of the muscle fatigue and the coordination.
The purpose of this study was to propose useful activities of daily living(ADLs)and scales for estimating ADL ability in healthy older persons.The subjects were 2100 older persons.A total of 130 items for 57 ADLs were selected from the following 4 domains:locomotion, manipulation, stability, and posture-change.The achievement rate for each item was calculated.First, 15 more useful ADLs, consisting of 45 items, were selected to estimate ADL ability based on the multiple scale, considering the achievement rate and interrelationship of each item, and physical fitness domains related mainly to achievement of the ADL.Second, the scales of 15 ADLs were modified after examining the difference between practical achievement rates and the theoretical structure of the scale from the viewpoints of size and approximation of the achievement rate.Third, useful ADLs and their scales were proposed based on the analysis and theoretical validity.As a result, the following 15 ADLs were selected:In the locomotion domain, jumping across a ditch, walking, running, going up and down stairs, going up and down bus steps, transfer, and jumping;in the manipulation domain, taking bedding in and out, buttoning a shirt;in the stability domain, standing in a bus or train, dressing while standing(trousers), dressing while standing(socks), standing on one foot with eyes open;in the posturechange domain, sitting up, standing up from the floor.All of these 15 ADLs were constructed on a 3-level scale with different difficulties.The ADL scale proposed in this study was considered to need further examination.
A study was conducted to examine relationships among the times allotted to each episode of teaching(instruction, management, motor learning, cognitive learning), the frequency of teacher feedback behavior, and student evaluation of physical education classes, in units of elementary school physical education.By analyzing these relationships, it was hoped to be able to find an effective transition pattern of episodes of teaching and teacher feedback behavior, thus improving the student evaluation score.The main findings were as follows:1)After analyzing 6 gymnastic units, 4 units showed the same tendency.In the first half of the units, teachers allotted plenty of time to instruction episodes.As the units continued, times for instruction episodes gradually decreased.Also, times for management episodes in the three units decreased in the latter half of the units.On the other hand, the time for motor learning episodes and the frequency of teacher feedback behavior increased slowly in the latter half of the units.Corresponding to these trends, student evaluation scores increased.2)However, 2 units did not show this tendency.In these units, the student evaluation scores did not increase.This was caused by two problem.One teacher with poor skills spent too much time on management and could not give enogh time to motor learning.In the other teacher, despite allowing enough time for motor learning and giving active feedback behavior, the learning task for students was too difficult to achieve.
Thirty-two male students who participated in the Tsukuba marathon race were measured for body mass(BM), grip strength(GS), maximal force and rate of force development(RFD)in isometric knee extension(ISO), jumping height(JH)for the counter-movement-jump(CMJ), and JH and contact time(CT)for the 5-rebound-jump(5RJ)before and after the race.Also, maximal oxygen uptake(VO_2max)and maximal steady state corresponding to an intensity giving a blood lactate level of 2.2mmol/l of blood lactate(MMS)of 22 of the subjects were measured on a separate day to the race.The results were as follows:1)Average race time was 3 h 55 min 27 s.Average running speed in the second half of the race was significantly lower than in the first half.2)BM, GS, maximal force and RFD in ISO, JH of CMJ, and JH of 5RJ and 5RJindex(=JH/CT)were significantly lower after the race.CT of 5RJ after the race also increased significantly.Furthermore, relative changes in the maximal force and RFD in ISO, CT of 5RJ and 5RJindex after the race were significantly greater than the relative changes in BM, GS and JH of CMJ after the race.3)Average running speed during the race was correlated significantly with VO_2 max and MSS.However, significant relationships were not observed between average running speed during the race and leg muscular strength or power measured before the race.4)The relative change in running speed from the first to the second half of the race was correlated significantly with the relative change in JH of 5RJ after the race.These results suggest that muscular strength and stretch-shorting cycle movement ability of leg muscles were damaged during the marathon race.Therefore, reducing this damage during the race may help to maintain running speed in the second half of the race.
This study was an attempt to clarify the insistence on "impulse"(Trieb)by Villaume, who was one of the Philanthropen, and argued about bodily education.The study also reexamined the theory of bodily education in the field of Philanthropen when modern physical education was still in its infacy.Up to now the only studies about Villaume have been "Von der Korperbilding"(1787)preceding "Gymnastik fur die Jugend"(1973)by GutsMuths, and his many other works have received little attention.The refore, this study focused on the concept of"impulse"by Villaume to examine preceding studies from a different perspective i.e.that the Philanthropen had the same opinion about the body or the power of mankind.Villaume considered"impulse"to be the motive power of the act.He through much of the "impulse"was a bodily power that reason could not control and that teachers had to be mindful of it.Such affirmative consciousness about bodily power was not found in the theory of GutsMuths, the father of modern physical education.
The purposes of this study were 1)to investigate the relationship between sprint running performance and isokinetic hip strength, and 2)to clarify the muscles that are important in sprinting from the standpoint of isokinetic strength and muscle cross-sectional area(CSA).Sixteen male(100m sprinting time 10.99±0.46s)and 12 female(12.50±0.44s)subjects ran 60m and their sprinting speed was measured from 30 to 60m.Isokinetic strength of hip and knee flexion and extension(Nm)were mesured at 60, 180 and 300 deg/s.Magnetic resonance imaging(MRI)was used to determine the muscle cross-sectional area of the thigh(upper, middle and lower femur)and trunk.In females, there were no significant correlations between sprinting speed and isokinetic strength.In males, there were significant correlations between sprinting speed and hip strength(absolute value)at all angular velocities(r=0.51-0.75, p<0.05-0.01), except for hip extension at 300 deg/s.Extension at 60 deg/s was significant(r=0.64, p<0.01)only in the male knee.In males, there were significant correlations between the peak torque of hip extension and muscle CSAs of the hamstring and adductor(r=0.50-0.63, p<0.05-0.01), as well as between the peak torque of hip flexion and muscle CSAs of the psoas major and adductor(r=0.59-0.83, p<0.05-0.001).These results suggest that sprint running performance in males is influenced by the strength of hip flexion and extension.In addition, the muscle volume of the hamstring, adductor and psoas major muscles appears to play an important roles during sprint running in males.
The purpose of the present study was to clarify the effects of sprint practice in physical education classes for 11- or 12-year-old elementary school children.The subjects were divided into two groups;a training group(12 boys and 8 girls)and a control group(13 boys and 8 girls).The training group performed sprinting prectice such as the starting dash and full sprint over a period of 2 weeks(6 physical education classes), while the control group had no special practice.The 50-m sprint time was measured to clarify the performance before and after the corresponding period in both groups.The training group was measured for sprint performance such as mean speed, mean step frequency, and mean step length every 10 m from the start up to 50 m.The results obtained were as follows:The 50-m sprint time of the training group decreased significantly for boys as well as girls.However, no significant changes were found in the control group.After training, the mean speeds in the training group in the sections from 10 to 20 m and from 40 to 50 m increased significantly for boys, and increased significantly in all the sections except from 20 to 30 m for girls.After training, for boys in the training group, the mean step length increased significantly from 10 to 20 m, from 30 to 40 m, and from 40 to 50 m, but the mean step frequency did not increase significantly.For girls in the training group, the mean step length increased significantly from 10 to 20 m, from 30 to 40 m, and from 40 to 50 m, and the mean step frequency increased significantly from 30 to 40 m and from 40 to 50 m.From these results, it is suggested that sprint practice for 2 weeks(6 times)should improve the sprint performance of sixth-grade elementary school children.
Even through the health benefits of regular exercise and physical activity are well documented, most people are inadequately active or completely inactive.Designing interventions to enhance the adoption and maintenance of a physically active lifestyle continues to be a challenge, given that the majority of individuals are not considering becoming more active, and that over half of those who decide to become more physically active return to a sedentary lifestyle within three to six months.It has been recommended that research on exercise adherence be conducted utilizing models of behavioral science.One of the most effective models is the transtheoretical model of behavior change(TTM).The TTM has been used to explain both the stages and processes people go through when trying to eliminate a negative form of behavior(e.g., smoking)and when trying to acquire a positive form of behavior(e.g., exercise).The model consists of various stages of change, processes of change, decisional balance, and self-efficacy.The TTM suggests that individuals attempting to change exercise behavior move through five stages of change.In addition, individuals experience different congnitive and behavioral processes of change as they move from one stage to another.As people change, decisional balance and self-efficacy are employed uniquely at each stage.According to this model, tailoring interventions to match a person's readiness(stage of change)is essential.Although research on exercise adherence utilizing the TTM has been actively conducted in Western countries, this area of research is yet to be advanced in Japan.This article reviews research on exercise adherence utilizing the TTM, and discusses the applicability of the TTM to understanding physical activity and exercise behavior in the Japanese population.