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. The previous studies showed that hold-relax stretching (HRS) was effective for improving the decreases in range of motion and muscle soreness. In addition, modified proprioceptive neuromuscular facilitation stretching (mPNF) was an equally effective for HRS. However, it was unclear whether there are differences between acute effects of HRS and mPNF on muscle strength and muscle soreness in eccentrically damaged muscle. Therefore, the present study aimed to compare the acute effects of HRS with those of mPNF on muscle strength and soreness in eccentrically damaged muscle. The participants comprised 40 volunteers randomly assigned to either the HRS group (N = 20) or the mPNF group (N = 20). Initially, the participants of both groups performed 60 maximal eccentric contractions of the knee extensors. Two days after this exercise, each group performed either HRS or mPNF 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 mPNF. The results showed that the muscle soreness observed after eccentric contraction significantly decreased immediately after both HRS and mPNF. In addition, there were no significant changes in muscle strength immediately after both HRS and mPNF. These results suggest that while both HRS and mPNF can effectively decrease muscle soreness without reducing performance.
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
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
Foot baths reportedly reduce pain and improve sleeplessness. In addition, foot baths may induce vasodilation, and thereby improve blood flow, reduce swelling, induce relaxation, and increase deep body temperature. However, the influence of foot baths on energy metabolism and physiological indices are unclear. Therefore, the present study aimed to clarify the effects of foot baths on energy consumption and physiological indices (e.g., heart rate, tympanic temperature, and blood pressure). Nine healthy males were included in this study (age, 23.0±1.0 years; body weight, 66.5±5.6 kg; body fat percentage, 15.1±4.3%). Expired gas composition (i.e., oxygen and carbon dioxide consumption) was analyzed using the Food method in an environmentally-controlled room (room temperature 25°Cand humidity 40%). Subjects were rested in the hood during the measurement. After 30 min rest in the sitting position, a 30 min foot bath was performed, after which the subjects sat for 60 min. Expired gas composition and heart rate were measured over time, and tympanic temperature and blood pressure were measured every 15 min. The foot bath involved immersion of the knees, and the temperature of the water was maintained at 41°C. There were no significant changes in energy consumption after the foot bath, and no significant changes in heart rate, tympanic temperature, and blood pressure. Therefore, our results suggested that there were no significant energy metabolism changes after 30 min of foot bathing at 41°C.
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>Many previous studies have reported that static stretching (SS) may decrease muscle stiffness and compromise muscles’ ability to produce maximal strength. However, the effects of SS at different repetition durations and numbers within a constant total time remain unclear. Therefore, the purpose of this study was to examine whether SS for a constant total time (2 min) with different repetition durations and numbers (e.g., 60 s × 2 times, 30 s × 4 times, and 10 s × 12 times) produces different changes in muscle stiffness and strength. Fifteen healthy males (mean age: 23.3 ± 1.0 years) participated in this study. Muscle stiffness was measured during passive ankle dorsiflexion using dynamometer and ultrasonography. In addition, muscle strength of the plantar flexors was measured using a dynamometer at 0° of plantarflexion with the hip and knee joints fully extended. Muscle stiffness and strength were measured before and immediately after SS. Each experimental protocol was conducted in random order with at least a 1-week interval but no longer than a 2-week interval between testing sessions. The results showed that there were no significant interaction effects on muscle stiffness and strength. However, in all experimental protocols, muscle stiffness and strength immediately decreased after SS. In conclusion, SS for a constant total of 2 min decreases muscle stiffness and strength regardless of repetition durations and numbers of each individual SS.</p>