[Purpose] The purpose of this study was to examine the change of muscle damage markers after maximal eccentric exercise and to verify the difference of recovery according to ACTN3 gene polymorphism. [Methods] Fifty healthy males participated in this study. Subjects performed 25 times/1 set (total 2 set) maximal eccentric contractions of the elbow flexor muscles on a modified preacher curl machine with a between-sets rest time of 5 min. Maximal isometric contraction (MIC) was measured 6 times (pre, post, after 24 h, 48 h, 72 h and 96 h). Muscle soreness (SOR) was measured 5 times (pre, after 24 h, 48 h, 72 h and 96 h). Blood samples were collected 5 times (pre, after 24 h, 48 h, 72 h and 96 h). ACTN3 gene polymorphisms were identified using polymerase chain reaction (PCR). Data were analyzed using a 2-way repeated measure ANOVA and post hoc Bonferroni test. [Results] Analysis of ACTN3 gene polymorphism revealed the following distribution: 22% RR (n=11), 50% RX (n=25), and 28% XX (n=14). Individuals were classified into the RR homozygote group (n=11) and the X-allele group (n=39). MIC showed a significant difference between groups and interaction (p<.05). The groups differed significantly in MIC at 48 h, 72 h, and 96 h after exercise and the X-allele group decreased more than the RR homozygote group. The groups differed significantly in muscle soreness and interaction (p<.05). SOR in the X-allele group was significantly higher than in the RR homozygote group at 24 h after exercise. Although blood CK activity was lower in the RR homozygote group than in the X-allele group, but there was no significant difference between the groups (p>.05). [Conclusion] The RR homozygote group showed lower muscle strength reduction rate, muscle soreness and blood CK activity than the X-allele group. This indicates that RR individuals have a lower risk of exercise-induced muscle damage than those with an X-allele.
PURPOSE The purpose of this study is to analyze the biomechanical variables involved in ballet dancers’ ankle muscle imbalance when performing relevé movements. METHODS The subjects of this study (n=14, age: 22.29±1.73 years old, height: 161.4±5.06cm, weight: 51.88±7.51kg) were 14 ballet dancers with 9 years of experience. Based on the reciprocal muscle strength ratio, the dancers were divided into the following groups: Close to the normal value (RMIS) and far from the normal value (RMIB) using the maximum values of plantar flexion and dorsiflexion of the ankle joint using an isokinetic measurement equipment (60°/sec). RMIB). The biomechanical variables, namely the ankle joint movement and ground reaction force, were subsequently measured. SPSS 26.0 was used for data analysis and independent t-test was used for statistical verification. RESULTS The ground reaction force in the Z (vertical) direction based on the ankle joint muscle strength imbalance of ballet dancers was significantly lower in the RMIB group. In addition, although it was not a statistically significant difference, the plantar flexion movement was lower in the RMIB group, and there was a significant difference in the generation of ankle joint movement in the Z direction. CONCLUSIONS In conclusion, in order for a ballet dancer to efficiently utilize the force generated from the supporting leg when performing a movement, ankle imbalance must be taken into consideration when training.
PURPOSE This study aimed to present isokinetic quadriceps and hamstring muscle strength values in K league 1 (K1) professional soccer players and compare these results to those of published studies. METHODS A total of 31 K1 soccer players (age 24.5±4.2) without a history of lower limb injury were included in this study. Isokinetic knee strength tests were implemented at a velocity of 60°·s-1 and 180°·s-1 for both dominant (D) and non-dominant (ND) legs using a dynamometer. Strength variables included peak torque (PT), body mass normalized PT (NPT), bilateral strength difference (BD), and hamstring to quadriceps strength (H/Q) ratio. RESULTS At 60°·s-1 velocity, the NPTs of the quadriceps were 3.39N·m·kg-1 and 3.33N·m·kg-1 for D and ND legs, respectively, and those of the hamstrings were 2.00N·m·kg-1 and 1.89N·m·kg-1 for D and ND legs, respectively. At 180°·s-1 velocity, the NPTs of the quadriceps were 2.31N·m·kg-1, 2.27N·m·kg-1 for D and ND legs, respectively, and those of the hamstrings were 1.42N·m·kg-1, 1.39N·m·kg-1 for D and ND legs, respectively. At all velocities, the BDs of quadriceps and hamstring muscles ranged from 6.6–7.8%, and H/Qs ranged from 57–62%. Compared to previous studies that did not consider the history of injury, this study showed lower levels of BD (less than 10%) and higher levels of NPT. CONCLUSIONS The presented isokinetic quadriceps and hamstring muscle strength values can be used as reference values for the isokinetic knee strength of K1 professional soccer players.
Purpose This study was conducted to analyze the differences of physical characteristics focused on the physique, strength, and power for cycling national athletes (Sprint cyclists and Road race cyclists). Methods We measured various factors (e.g., height, weight, body fat ratio, thigh circumference, waist circumference, anaerobic power, isokinetic muscular strength, muscle power, squat jump by 1RM intensity, and so on) for a total 11 male cycling national athletes (5 Sprint cyclists and 6 Road race cyclists). Results First, the body composition showed the significant differences only in weight (p=0.31) and BMI (p=.001) for Sprint cyclists. Second, the values of the anaerobic power for the Sprint cyclists were significantly higher than those for the Road race cyclists only at peak power (p=0.28), whereas there was no significant difference in average power, isokinetic muscular strength, and muscle power between the two groups. Third, the isokinetic trunk flexion muscle (p = .016) for the Sprint cyclists were significantly higher than those for the Road race cyclists. Fourth, the significant difference in Time to Peak Torque was not found between two groups. Fifth, the values for the Sprint cyclists showed the significant difference in all 5 intensity groups (0%, 30%, 50%, 60%, and 80%) (p=.001) of the squat jump. Also, there was a statistically significant difference only in 0% velocity between the two groups, except for exercise intensity. Conclusions From the various measures between two groups, the Sprint cyclists relatively showed the high weight, BMI (muscle mass), and maximum power. Additionally, the isokinetic trunk flexion muscle and the squat jump were higher in the Sprint cyclists than the Road race cyclists. These data may be used as basic data to improve the physical fitness factors related to the athletic performance of the athletes by reflecting them in the effective training plan and evaluation of the athletes.
The purpose of this study was to explore and confirm Kumi-kata related factors of muscle strength by performance level in Korea elite female judoists. In order to achieve this purpose, 14 elite female judoists participated to this study. The subjects were divided to two groups (World Class Group and Non-World Class Group) according to their world ranking level(by ranked 30th). The analysis factors were repeated grip strength, Kumi-kata specific pulling strength and isokinetic strength of trunk joint. The results were as follows: Firstly, World Class Group had significantly higher repeated grip strength as compared to non-world class group (p<.001). Secondly, World Class Group had significantly higher specific Kumi-kata pulling strength as compare to non-world class group (p<.05). Finally, The differences between the two groups for isokinetic strength of trunk joint were non-significant. The results of this study indicates that a strong relationship exist between Kumi-kata related specific muscle strength and performance level in korea elite female judoists.
PURPOSE This study aimed to investigate the effects of accelerated rehabilitation exercise on physical fitness, lower extremity isometric strength, and blood variables in older adult women diagnosed with degenerative osteoarthritis. METHODS A total of 29 older adult women diagnosed with degenerative osteoarthritis residing in G city participated in the study, and 19 participants, excluding dropouts, took part in the experiment. They underwent exercise twice a week for 60 minutes per session over a period of 12 weeks. Pre- and post-experiment, the older adult fitness assessment (SFT), lower extremity isometric strength, and blood variables were measured. Data analysis was performed using SPSS 25.0, and paired sample t-tests were conducted to examine the effects before and after exercise. RESULTS The study results showed significant differences in body mass index (BMI) before and after exercise (p<0.05), and the older adult fitness assessment (SFT) showed significant differences in all items (p<0.01). Lower extremity isometric strength showed significant differences in absolute (Nm) and relative (%BW) values of 20° right flexion muscle (p<0.01). In terms of blood variables, significant differences were observed in creatine and ESR before and after exercise (p<0.01). CONCLUSIONS This study’s results suggest that regular physical activity and rehabilitation exercise programs can positively impact the muscular strength, cardiovascular endurance, exercise function, and blood composition of older adult women diagnosed with degenerative osteoarthritis. It is indicated that conducting future research, including periodic exercise programs, could be beneficial in promoting sustained exercise participation.
Purpose The purpose of this study were to assess physiological and biochemical characteristics in elderly women with osteosarcopenic obesity (OSO), and to analyze relationships among irisin, adipokines and bone metabolism markers. Methods 126 elderly women were selected and among them 10 women were classified into OSO group (76.9±5.2 yrs) and 14 women were classified as a NOSO group (72.9±5.6 yrs). Physique, body composition and bone mineral density were measured. Senior fitness tests were 30-s chair stand, 30-s arm curl, chair sit-and-reach, back scratch, 8-foot up-and-go, grip strength, and 2-min step test. Isokinetic muscle strength was measured by isokinetic dynamometer (Cybex 770, USA). Nutrition intake and physical activity were administered. Biochemical parameters including irisin, FNDC-5, leptin, adiponectin, CTx, 25(OH)D, osteocalcin, and PTH were measured. All data were analyzed by SAS 9.4. Independent t-test was applied to compare between OSO and NOSO groups. Multiple regression analysis was used. The level of significance was set at .05. Results The results of the study showed that there were significantly high for waist circumference, hip circumference, WHR, and BMI in OSO group compared to those of NOSO group. Higher results were also obtained for fat tissue and percent body fat but significantly low for lumbar bone mineral density. OSO group showed significant lower results for grip strength and 2-min step test compared to NOSO group. Peak torque, and relative peak torque at 60° were significantly lower for left and right knee flexion in OSO group. Protein intake was significantly low in OSO group, but no difference was obtained in level of physical activity between two groups. Irisin was significantly related to adiponectin, FNDC-5 and osteocalcin in explaining 35.2%, 81.5% and 92.1% of the variance, respectively. Conclusions This study shows that elderly women with OSO have higher results for physique and body composition parameters except body height. However, lower values were obtained for functional fitness, and isokinetic muscle strength. OSO may have more risks for metabolic syndrome, bone fractures, fall, lack of daily physical activity and limit of locomotion due to the imbalance of quadriceps and biceps femoris in non dominant leg. This study suggests that criteria and mechanism of OSO should be clarified by follow-up study.
Purpose The purpose of this manuscript was to investigate the effect of high and low speed blood flow restriction versus non-blood flow restriction isokinetic exercise on isometric muscle strength, muscle fatigue, and muscle contraction displacement. Methods The subjects were consisted of ten males without non-specific muscular skeletal disease. They were classified into four training groups: ① high speed(300°/s) without blood flow restriction, ② high speed(300°/s) under blood flow restriction, ③ low speed(90°/s) without blood flow restriction, ④ low speed(90°/s) under blood flow restriction. Before and after the intervention, all of the subjects underwent measurements of isometric quadriceps strength, muscle fatigue, and muscle contraction displacement. Results In regard to isometric quadriceps strength before & after intervention, there was no significant difference between groups. For the lactic acid measurement before & after intervention, there was a signigicant difference between groups(p<.05). Also, there was a significant difference between groups(p<.05) in muscle contraction displacement in terms of Dm but there was no significant difference between groups in terms of Tc Conclusions Isokinetic exercise with blood flow restriction had effects on lactic acid and muscle contraction displacement.
The past few decades has seen increasing kinematic studies using surface electoromyography (EMG) in archery, however there has been no such specific study in Korean traditional archery. The purpose of this study was to evaluate EMGs during archery shooting motion in Korean traditional archers. Ten men Korean traditional archers were participated, and divided into two groups according to the shooting stance; parallel stance group(PSG, n=5) and oblique stance group(OSG, n=5). The surface EMGs were measured 12 muscles during shooting motion of five events including Junbi(Set), Geogung(Set up), Manjak(Full draw), Balsi(Release), Machigi(Ending). At the result, muscle activity of posterior deltoid, trapezius, rhomboid major, latissimus dorsi, biceps brachii, forearm extensor bundle, triceps brachii, levator scapulae significantly increased at event of full draw and release, then significantly decreased again at event of ending, respectively(p<.01, p<.001). The muscle activity of erector spinae(ES) was also significantly increased at event of full draw and release(p<.01, p<.001), while no significant changes in muscles of rectus abdominis, rectus femoris(RF), gluteus maximus. As a result of comparing PSG and OSG, muscle activity of RF in OSG was higher than PSG at event of release(p<.05), it remained until event of ending(p<.05). On the other hand, the higher the tension of the bow, the higher the muscle activity of the draw arm at event of release(p<.05). These results suggest that when Korean traditional archery shooting, both side arm and back muscles are more activated than the abdomen, leg and hip muscles. The parallel stance might suppress the muscle activity of the lower extremities to twist the upper body. And the higher bowstring tension needs to increase of muscle strength in BB of draw arm.
PURPOSE The purpose of this study was to investigate the characteristics of field and on-ice performances of ice-hockey players and the relationship of performance with subjective joint pain and dysfunction. METHODS A total of 25 male college icehockey players were evaluated for 19 items of performance. Pain and dysfunctions in the lower extremities and lower back were confirmed through the Foot and Ankle Outcome Score, Knee Injury and Osteoarthritis Outcome Score, Hip Dysfunction and Osteoarthritis Outcome Score, and Osweatry Disability Index questionnaire. Players with similar performance characteristics were classified through a cluster analysis, and differences in performance and patient-reported outcomes between clusters were analyzed with a one-way analysis of variance. RESULTS The ice-hockey players were classified into “lower muscular strength and performance (cluster 1),” “lower cardiorespiratory endurance (cluster 2),” and “high muscular strength and performance (cluster 3).” Players in cluster 1 had more frequent ankle and knee joint dysfunctions and pain compared to those in cluster 3. Several performance test items affected the subjective joint score, and the related performance items were more in the proximal joint than in the distal joint. CONCLUSIONS Ice hockey players should perform training to supplement their individual lack of on-ice and field performance. Since performance may be limited because of joint dysfunction and pain, a joint-specific intervention strategy should be applied to improve physical and athletic performances.
