Hamstring muscles’ function deficit during overground sprinting in track and field athletes with a history of strain injury

ABSTRACT

In this study, we aimed to clarify the characteristics of neuromuscular function, kinetics, and kinematics of the lower extremity during sprinting in track and field athletes with a history of strain injury. Ten male college sprinters with a history of unilateral hamstring injury performed maximum effort sprint on an athletic track. The electromyographic (EMG) activity of the long head of the biceps femoris (BFlh) and gluteus maximus (Gmax) muscles and three-dimensional kinematic data were recorded. Bilateral comparisons were performed for the EMG activities, pelvic anterior tilt angle, hip and knee joint angles and torques, and the musculotendon length of BFlh. The activity of BFlh in the previously injured limb was significantly lower than that in the uninjured limb during the late-swing phase of sprinting (p < 0.05). However, the EMG activity of Gmax was not significantly different between the previously injured and uninjured limbs. Furthermore, during the late-swing phase, a significantly more flexed knee angle (p < 0.05) and a decrease in BFlh muscle length (p < 0.05) were noted in the injured limb. It was concluded that previously injured hamstring muscles demonstrate functional deficits during the late swing phase of sprinting in comparison with the uninjured contralateral muscles.     

Postcontraction Influences on Reaction Time

Abstract

The purpose of this study was to compare reaction time (RT) and fractionated RT components (premotor and motor times) between normal and postcontraction conditions. Twelve participants performed 20 trials each of control and postcontraction RT conditions. For the control condition, participants executed a learned, rapid, knee-extension contraction response to an auditory stimulus. The postcontraction condition was identical to the control condition except that the participants performed a 3-s isometric contraction of the knee extensor muscles prior to an auditory stimulus. Muscle activity was recorded from the quadriceps muscle group. Results indicated that the postcontraction condition was significantly faster than the control condition for the average RT, premotor time, and motor time. It was concluded that reaction time, processing time, and muscle contraction time for a learned task could be significantly reduced following an isometric contraction.     

Examining BIBFRAME 2.0 from the Viewpoint of RDA Metadata Schema

This article examines BIBFRAME 2.0 from the viewpoint of RDA metadata schema, that is, whether the present BIBFRAME is suitable for exchange and sharing of metadata created with RDA. First, an overview of RDA and BIBFRAME models is provided. Second, mapping examples of metadata records and part of the mapping tables from RDA to BIBFRAME are demonstrated. Third, some issues involved in the mapping are investigated: treatment of RDA Expression in BIBFRAME, mapping of RDA elements to BIBFRAME properties, and conversion of extant MARC21 bibliographic records to BIBFRAME metadata.     

Dynamics of community participation,student achievement and school management: the case of primary schools in a rural area of Malawi

School management in many sub-Saharan African countries has been enhanced through community participation in an attempt to improve education quality. This study uses field research in a rural district of Malawi to assess how community and parent participation differs between schools, the intentions of communities and parents when carrying out activities in schools, and the mechanism promoting active participation in schools. In high-achieving schools, but not in low-achieving schools, communities and parents were actively involved in events aimed at improving student achievement. Communities and parents considered most highly prioritised activities that directly influenced student achievement, including hiring volunteer teachers, arranging extra classes and holding mock examinations. Community participation did not directly improve student achievement. Instead, when communities and parents actively participated in a school, school management improved, ensuring better student achievement. The implications of this finding are discussed in relation to community participation.     

Attributes of meaningful learning experiences in an outdoor education program

This phenomenological study sought to identify the attributes of meaningful learning experiences as found in an outdoor education program. Thirteen students in the Wilderness Writing Program at Brigham Young University were the sample of this study. Their participation in outdoor recreational activities and their reflections about their experiences were analyzed. Through written journal entries, group discussions, observations, and writing assignments, a qualitative analysis identified attributes that occurred in their meaningful learning experiences. Meaningful learning was defined as a realization of a person's weaknesses, strengths, and potentials. This realization came through experiences with attributes of a degree of perceived risk, which led to a feeling of awkwardness, followed by a purifying process, or sublimation. A reflective period allowed for reconstruction of a person's view of himself or herself and this was closely tied with feedback from others in the group.     

Kinetic analysis of the lower limbs in baseball tee batting

The purpose of this study was to investigate effects of the ground reaction forces on the rotation of the body as a whole and on the joint torques of the lower limbs associated with trunk and pelvic rotation in baseball tee batting. A total of 22 male collegiate baseball players participated in this study. Three-dimensional coordinate data were acquired by a motion capture system (250 Hz), and ground reaction forces of both legs were measured with three force platforms (1,000 Hz). Kinetic data were used to calculate the moment about the vertical axis through the body’s centre of mass resulting from ground reaction forces, as well as to calculate the torque and mechanical work in the lower limb joints. The lateral/medial ground reaction force generated by both legs resulted in the large whole body moment about its vertical axis. The joint torques of flexion/extension of both hips, adduction of the stride hip and extension of the stride knee produced significantly larger mechanical work than did the other joint torques. To obtain high bat-head speed, the batter should push both legs in the lateral/medial direction by utilising both hips and stride knee torques so as to increase the whole body rotation.     

Physical activity levels in American and Japanese men from the ERA-JUMP Study and associations with metabolic syndrome

Background:Metabolic syndrome(MetS) is a global health problem.Physical activity(PA) is a known modifiable risk factor for MetS and individual MetS components.However,the role of PA could differ between sub-populations due to differences in the variability of PA and other MetS risk factors.To examine these differences,multi-country studies with standardized outcome measurement methods across cohorts are needed.Methods:Cross-sectional PA levels(total and domain specific) in healthy middle-aged(44-56 years) men in the Risk Factor Assessment among Japanese and U.S.Men in the Post-World War Ⅱ Birth Cohort(ERA-JUMP) Study(n=730;American:n=417;Japanese:n=313;from population-representative samples in Pittsburgh,Pennsylvania,USA,and Kusatsu,Shiga,Japan) were compared.The relationships between PA levels and MetS(overall and specific components) in/across the American and Japanese sub-cohorts(adjusting for age,smoking,and alcohol consumption)were also assessed using the same instruments(pedometer and validated questionnaire) to measure PA in both cohorts.Results:A total of 510 individuals provided complete data on PA(American:n=265;Japanese:n=245).The American cohort had significantly lower mean±SD steps/day(7878±3399 steps/day) vs.the Japanese cohort(9055±3797 steps/day)(p <0.001) but had significantly higher self-reported moderate-vigorous leisure PA(American:15.9(7.4-30.3) metabolic task equivalent hours per week(MET-b/week) vs.Japanese:4.0(0-11.3) METh/week,p <0.0001).In both sub-cohorts,each 1000 steps/day increase was associated with lower odds of having MetS(American:OR=0.90,95%CI:0.83-0.98;Japanese:OR=0.87,95%CI:0.79-0.95) and the individual MetS component of high waist circumference(American:OR=0.86,95%CI:0.79-0.94;Japanese:OR=0.87,95%CI:0.80-0.95).In the American cohort only,higher self-reported leisure PA(Met-b/week) was associated with lower odds of MetS and high waist circumference(OR=0.98,95%CI:0.97-0.99 for MetS and waist circumference,respectively).Conclusion:Higher total step counts/day had an important protective effect on MetS prevalence in both the Japanese and American cohorts,despite differences in PA levels and other MetS risk factors.The effect of steps/day(across all intensity levels) was much greater than domainspecific moderate-vigorous PA captured by questionnaire,suggesting the need for measurement tools that can best capture total movement when examining the effects of PA on MetS development.     

Effects of intense exercise on the physiological and mental condition of female university judoists during a training camp

To clarify the physical and mental fatigue caused by intense exercise and the relationship between the two types of fatigue, we examined changes in anthropometric and biochemical variables, neutrophil function, and the Profile of Mood States (POMS) questionnaire in 13 female university judoists attending a one-week training camp. Blood glucose, total cholesterol, haemoglobin, leukocyte count, IgG, and phagocytic activity all decreased after the training camp compared with baseline (P < or = 0.046). Aspartate aminotransferase, lactate dehydrogenase, creatine kinase, and neutrophil oxidative burst activity increased after the training camp (P < or = 0.007). Of the POMS scores, that for Fatigue increased after the training camp (P = 0.041) and that for Vigour decreased (P = 0.042). The changes in several POMS scores correlated with the changes in blood biochemical variables. In particular, the change in Total mood disturbance was negatively associated with changes in myogenic enzymes (P < or = 0.032). Our results suggest that intense exercise during training camps for female judoists leads to the appearance and accumulation of mental and physical fatigue, which are related to each other.