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 purpose of this study was to determine whether maximum repetition number can be used as an indicator of strength imbalance. Eleven healthy, resistance-trained males were tested for one repetition maximum (1-RM) the chest-press exercise, and than manual muscle testing (MMT), two-arm at 80% of 1-RM and one-arm at 40% of 1-RM in the pectoralis major were measured for the maximum voluntary contraction (%MVC) and maximum number of repetitions during the chest press exercise. Exercise velocity was constantly 4 seconds (concentric: 2-s, eccentric: 2-s) per repetition. The changes in %MVC were significantly higher in non-dominant limb (NDL) compared with dominant limb (DL) pectoralis major during two-arm chest press (p < 0.01) and one-arm chest press exercise (p < 0.05). In contrast, the changes in MMT (p < 0.05) and maximum repetition number (p < 0.01) were significantly higher in DL compared with NDL during one-arm chest press exercise. There was no correlation between maximum repetition number and MMT (rho = 0.331, p = 0.320). However, maximum repetition number was significantly negative correlated with %MVC in two-arm chest press (rho = -0.730, p = 0.011). It is possible that maximum repetition number can be used as an indicator of strength imbalance.
Impact of 9-week strength training of racing cyclist candidate during training camp on body composition, racing cyclist specific fitness, and racing cycle performance was examined. Two by two (cyclist experience, y/n and strength training (ST) participation, y/n) experiment design was employed. A total of 20 candidates participated and divided evenly into four groups; 1) experienced cyclist participating ST (CST), 2) non-experience cyclist participating ST (nCST), 3) experienced cyclist no participating ST (CnST), and 4) non-experience cyclist no participating ST (nCnST). Two programs were introduced; 1) non ST containing, pre-existing program emphasizing on sprint and acceleration training and 2) new-program containing ST and sprint and acceleration training. CST and nCST participated the latter program. Before and after the 9-week training, body composition, racing cyclist specific fitness, and racing cycle performance was tested. After 9 weeks, all groups decreased body weight(p<0.05), body fat content(p<0.05), body mass index, and CST and nCST increased lean body mass(p<0.05). Muscular strength measures such as grip strength, low back strength, 1RM of bench press, 1RM of squat, and anaerobic capacity improved after 9 weeks in all groups(p<0.05). The magnitude of changes was greater in order of CST, nCST, CnST, nCnST. Time trial of 200 meter sprint was faster after 9 weeks in all groups except CnST while 500 meter sprint was improved only in nCnST(p<0.05). After 9 weeks, regardless of previous cyclist experience, those who participated in ST ranked high places at racing cycle competition. Both training programs for the candidates improved body composition and racing cyclist specific fitness. When strength training was added to pre-existing training program emphasized on sprint and acceleration, the racing cycle performance was enhanced. Strength training for racing cyclist is highly recommended to improve their racing performance.
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 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] The purpose of this study was to provide the physiological characteristics of female adults in their 30s by comparing the body composition and the maximal strength of the knee extension and flexion and bilateral ratio and ipsilateral ratio(H/Q: Hamstring and Quadriceps ratio) depending on age. [Methods] Body composition was measured by Hv-ps 7681(GE medical systems Lunar, USA). Isokinetic lower limb muscular strength was measured by Isomed2000(D&R Ferstl GMBH, Germany). 92 volunteers who were chosen by our selection criteria agreed to participate in our study. The participants were divided into three groups depending on age and classified as female adults in twenties(n=30), in thirties(n=34), in forties(n=28). To evaluate differences according to age, One-way ANOVA was used. [Results] The result in the test for female adults is as follows. In body composition, there were significant differences in lean mass, bone mineral density in the legs area among groups(p<.05). In isokinetic test, there were significant differences in muscular strength among groups in extensor of knee(p<.05). [Conclusion] The finding revealed that strength training based on the characteristics depending on age is required and ipsilateral ratio needs to be improved.
[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 This study aimed to examine the effects of an 8-week gluteus medius strengthening exercise on back pain, balance, and strength in female office workers with low back pain. METHODS The participants of this study were female office workers aged 30 to 48 years old who reported low back pain on a visual analogue scale (VAS) ranging from 3 to 7. Twenty-six participants were randomly assigned to the exercise (n=13) and control (n=13) groups. The study applied a gluteus medius strengthening program to the exercise group for 8 weeks, three times a week, and 60 minutes per session. The participants in the control group were asked to maintain their normal life patterns during the period of intervention. Data collected from the test were analyzed through repeated two-way ANOVA, paired t-test, and independent t-test. RESULTS First, there has been a significant decrease in the pain level, as evidenced by VAS and Korean oswestry disability index (KODI) scores. Second, there was a statistically significant improvement in both static and dynamic balance capabilities. Last, back strength also significantly improved. CONCLUSIONS Application of the gluteus medius strengthening exercise appears to be effective for low back pain, static and dynamic balance capabilities, and back strength.
PURPOSE This study investigated the effect of non-linear periodization strength training on basic and professional fitness of national cross-country skiers. METHODS The body composition (height, weight, BMI, body fat %), basic physical strength (grip strength, lung capacity), anaerobic power (peak power, average power), graded exercise test (maximum heart rate, running time, VO2max, lactic acid), isokinetic strength (trunk strength), and 1RM (bench press, dead-lift, squat, shoulder press, leg curl, bicep curl, cable triceps extension) of nine national cross-country skiers (male: 5, female: 4) were measured. All analyses were performed using SPSS 25.0, Kruskal-Wallis H tests were applied to observe the changes by training methods. Mann-Whitney U tests were used as Post Hoc. RESULTS The results indicated that running time and VO2max post-test improved compared to that for the pre-test for graded exercise test. The lumbar extension strength of the post-test was higher than that for pre-test. There was no significant difference in other variables. CONCLUSIONS It is suggested that nonlinear periodization strength training can be expected to improve running time, VO2max, and trunk strength for cross-country athletes; however, it does not affect the overall changes.
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.
