ABSTRACT
It is well known that eccentric exercise induces muscle damage that is characterized by a prolonged decrease in muscle strength and range of motion, development of delayed onset muscle soreness, and swelling. Therefore, the present study aimed to compare the acute effects of hold-relax stretching (HRS) with those of static stretching (SS) on muscle strength and soreness. The participants comprised 28 male volunteers randomly assigned to either the HRS group (N = 14) or the SS group (N = 14). Initially, the participants of both groups performed 60 maximal eccentric contractions of the knee extensors. Two and four days after this exercise, each group performed either HRS or SS for 60 s at a time and repeated them six times for a total of 360 s. Muscle strength and soreness during stretching and contraction were measured before and immediately after HRS and SS. The results showed that the muscle soreness observed after eccentric contraction significantly decreased immediately after both HRS and SS were performed two and four days later. In addition, there were no significant changes in muscle strength immediately after both HRS and SS were performed two and four days later. The rate of change in muscle soreness after HRS was significantly higher than that after SS two days post eccentric contractions. These results suggest that while both HRS and SS can effectively decrease muscle soreness, the effect of HRS on muscle soreness was larger than the effect of SS.
ABSTRACT
Resistance training is a treatment for muscle weakness and muscle atrophy. Although previous studies reported that muscle strength increased via changes in neural adaptation after low-intensity resistance training with skin cooling (SC), the effects of the training on both muscle strength and muscle thickness were unclear. Therefore, this study investigated the effect of low-intensity training of the triceps brachii with SC on muscle strength and muscle thickness. Volunteers were 12 healthy men, with one arm randomly assigned to SC and the other to control groups. Elbow extension exercises were performed for 8 weeks, and 1 repetition maximum (RM) and muscle thickness of triceps brachii were measured before and after training. Resistance exercise was performed thrice a week using a dumbbell adjusted to 50％ of 1 RM for both the groups. The SC side used an ice bag secured to the triceps brachii during training. There were no significant interaction effects of 1 RM and muscle thickness of triceps brachii；however, both variables significantly increased after training in both the SC and control groups. Muscle strength and muscle thickness increased after the 8-week training program with SC. No significant differences were observed between the groups.
ABSTRACT
The purpose of this study was to investigate the changes in patellar tendon length during passive knee flexion in the menstrual cycle. The right knee joints of 10 adult women with stable menstrual cycles were evaluated. Measurement of patellar tendon length was performed when the knee joint was bent flexibly at six angles (0°, 30°, 60°, 90°, 110°, and 130°), and the long-axis image of the patellar tendon was transversely superimposed at each angle. A photograph was taken with an ultrasonic device. Measurements were performed once during each of the four phases of the menstrual cycle (menstrual, follicular, ovulatory, and luteal phases) classified by the basal body temperature method. There were no significant differences in patellar tendon length at each knee flexion angle in each phase of the menstrual cycle. In the luteal phase, the patellar tendon was stretched significantly at 90° and 130° compared to knee flexion of 0°.
ABSTRACT
Resistance training is a treatment for muscle weakness and muscle atrophy. Although previous studies reported that muscle strength increased via changes in neural adaptation after low-intensity resistance training with skin cooling (SC), the effects of the training on both muscle strength and muscle thickness were unclear. Therefore, this study investigated the effect of low-intensity training of the triceps brachii with SC on muscle strength and muscle thickness. Volunteers were 12 healthy men, with one arm randomly assigned to SC and the other to control groups. Elbow extension exercises were performed for 8 weeks, and 1 repetition maximum (RM) and muscle thickness of triceps brachii were measured before and after training. Resistance exercise was performed thrice a week using a dumbbell adjusted to 50％ of 1 RM for both the groups. The SC side used an ice bag secured to the triceps brachii during training. There were no significant interaction effects of 1 RM and muscle thickness of triceps brachii；however, both variables significantly increased after training in both the SC and control groups. Muscle strength and muscle thickness increased after the 8-week training program with SC. No significant differences were observed between the groups.
ABSTRACT
<p>Non-contact anterior cruciate ligament (ACL) injury is one of the most severe knee problems for female athletes. Several studies have reported that the decreased lower limb control of women such as decrease of hip abductions muscle strength increase the risk of ACL injury. Also ACL Injury often occurs as a result of knee valgus collapse during single leg landing or pivoting in sports activities like basketball. Female basketball players often show an excessive knee valgus and hip adduction during the play. The purpose of this study was to analyze the effect of hip abductions muscle strength on knee alignment during a single leg landing. Thirty healthy female basketball players participated in this study. Mean age, height, body weight and plyer career were 17.3 years old±3.7, 162.7cm±17.2, 56.2kg±10.9, 8.9 years±3.8 respectively. All subjects were obtained written consent from after explanation of the procedure. Significant negative correlations showed that greater hip abductor peak torque (hip flexion 0 and 30degrees) exhibited less motion toward the knee valgus direction during single leg landing. And also, dynamic Trendelenburg test showed that all positive reactions cause knee valgus direction. These results suggest keeping proper knee position safety during single leg landing; female basketball player should improve the hip abductions muscle strength. Hip joint control will be a major issue for prevention of the non-contact ACL injury.</p>
ABSTRACT
<p>The purpose of this study is to clarify the effect of hip, knee, and ankle joint contractures on the joint angle and joint moment during standing posture using a mechanics simulation. A two-dimensional segment model (trunk, thighs, shanks, and feet) was created, and the standing postures for various hip, knee, and ankle joint angle configurations were generated (i.e. 743 types of standing postures). The hip, knee, and ankle joint contractures were reproduced by manipulating the joint stiffness, and optimal standing posture when the minimum value of the sum of muscle activities was obtained. When the hip joint contracture was developed during standing posture, the hip and knee flexion angle, and the hip and knee extension moment increased as well. When the knee joint contracture was developed during standing posture, the hip and knee flexion angle, ankle dorsiflexion angle, and the knee extension moment increased. When the ankle joint contracture was developed during standing posture, the hip flexion angle and the ankle plantarflexion angle increased and the knee joint was extended; the hip extension moment and knee flexion moment also increased. The findings of this study may help to improve abnormal standing posture through physical therapy.</p>