• The Korea Journal of Herbology
• /
• v.30 no.2
• /
• pp.37-42
• /
• 2015

Objectives : The aim of this study was to investigate the effects of licorice supplementation on muscle injury, plasma cortisol, testosterone and insulin sensitivity after high intensity resistance exercise. Methods : The fourteen health college male students were voluntarily participated in this study and were randomly divided into 2 groups: Control group (CON, n=7), Licorice group (LR, n=7). LR group ingested 2 g/time of licorice extract (mixed with 100 ml of water) two times/day for 10 days while the CON group ingested 100 ml of water. All subjects performed a high intensity resistance exercise (half-squat, 8 RM at 80% one-repetition maximum, 5 sets, 1min rest). Blood samples were collect before (-7) and after (0) licorice supplementation, and then 1 day, 2 day and 3 day post exercise. After 10 day treatment, plasma creatine kinase, cortisol, testosterone, glucose, insulin were measured. To determine the insulin sensitivity, HOMA-IR was calculated. Results : Plasma creatine kinase activities were significantly elevated after exercise, but there was not different between two groups. The plasma cortisol and testosterone levels were not significantly different between two groups. Plasma glucose levels were increased at 1 day and 2 day after exercise in the LR comparing with CON group (P<0.05) but plasma insulin levels were significantly lower in comparison with CON. HOMA-IR were significantly lower in the LR than CON group at 0 day to 3 day (P<0.05). Conclusions : The results of the current study suggest that licorice supplementation for 10 days might not attenuate the high-intensity exercise-induce muscle injury but may enhance the whole-body insulin sensitivity.

• Korean Journal of Applied Biomechanics
• /
• v.27 no.3
• /
• pp.197-203
• /
• 2017

Objective: The purpose of this study was to determine how exercise intensity affects muscle activity and kinematic variables during squat. Method: Fifteen trainers with >5 years of experience were recruited. For the electromyography (EMG) measurements, four surface electrodes were attached to both sides of the lower extremity to monitor the rectus femoris (RF) and biceps femoris. Three digital camcorders were used to obtain three-dimensional kinematics of the body. Each subject performed a squat in different conditions (40% one-repetition maximum [40%1RM], 60%1RM, and 80%1RM). For each trial being analyzed, three critical instants and two phases were identified from the video recording. For each dependent variable, one-way analysis of variance with repeated measures was used to determine whether there were significant differences among the three different conditions (p<.05). When a significant difference was found, post hoc analyses were performed using the contrast procedure. Results: The results showed that the average integrated EMG values of the RF were significantly greater in 80%1RM than in 40%1RM during the extension phase. The temporal parameter was significantly longer in 80%1RM than in 40%1RM and 60%1RM during the extension phase. The joint angle of the knee was significantly greater in 80%1RM than in 40%1RM at flexion. The range of motion of the knee was significantly less in 80%1RM than in 40%1RM and 60%1RM during the flexion phase and the extension phase. The angular velocity was significantly less in 80%1RM than in 40%1RM and 60%1RM during the extension phase. Conclusion: Generally, the increase of muscle strength decreases the pace of motion based on the relation between the strength and speed of muscle. In this study, we also found that the increase of exercise intensity may contribute to the increase of the muscle activity of the RF and the running time in the extension phase during squat motion. We observed that increased exercise intensity may hinder the regulation of the range of motion and joint angle. It is suitable to perform consistent movements while controlling the proper range of motion to maximize the benefit of resistance training.

• Journal of the Korea Convergence Society
• /
• v.12 no.6
• /
• pp.27-32
• /
• 2021

The purpose of this study was to compare the immediate effect of EMS (electrical muscle stimulation) on rectus femoris thickness during resisted knee extension exercise in healthy adults. This experiment was conducted on 20 healthy adults as pretest-posttest nonequivalent one group design. The subject's 1RM of both knee extension was measured indirectly using an elastic band, and the knee extension resistance exercise using an elastic band was applied to high intensity (80% of 1RM) on the right leg and low intensity (50% of 1RM with EMS) on the left leg, which were applied with 5 sets. Muscle measurements were performed on the rectus femoris (1/2 site, 1/4 site) using ultrasonography before and after exercise. There was a statistically significant difference on the thickness of the rectus femoris in low intensity exercise of the elastic band applied with EMS between pre-test and post-test (p<.05). The results of this study showed that elastic band low intensity exercise combined with EMS had an immediate effective in increasing the thickness of rectus femoris. Based on this result, it is also necessary to verify the effectiveness of intervention methods incorporating low-intensity resistance exercises applying EMS to elderly who cannot exercise high-intensity resistance training in the future, and to develop exercise programs for various body parts.

• 한국체육학회지인문사회과학편
• /
• v.54 no.1
• /
• pp.505-514
• /
• 2015

The purpose of this study was to examine the muscle activation in trunk and low-limbs muscle during squat exercise on various instability surface. 10 subject performed squat with 75% of 1 repetition maximum (1RM) on a stable floor, stability blue, stability black and BOSU. Electromyographic (EMG) activity was measured trunk muscle such as rectus abdomina (RA), external obliques (EO), internal obliques (IO), multifidus (MF), and low-limbs muscle such as gluteus maximus (GMA), gluteus medius (GME), biceps femoris (BF), rectus femoris (RF), vastus medialis oblique (VMO), vastus lateral oblique (VLO), medialis gastrocnemius (MG), lateral gastrocnemius (LG), soleus (SOL) and anterior tibia (AT) when ascending and descending squat phase. One-way ANOVA repeated measure with Sheffe used to compare the muscle activity on the stable and unstable surface. Squat with BOSU ball induces higher muscle activity of IO, MF, GMA and GME compared with stability and stability blue and blackduring descending motion. Squat with BOSU ball induces higher muscle activity of GMA compared with stability and stability blue and blackduring ascending motion. This results suggested that BOSU ball in the squat could be effective increasing of trunk stability and gluteal muscle activity. However, there was no difference of squat on low-limb muscle with or without instability.