PURPOSE: The effect of hydroxymethylbutyrate (HMB) supplementation on leucine is a major area of interest in exercise science. The present review aimed to investigate the various effects of HMB supplementation and provide guidelines for its practical use.
METHODS: This review collected and analyzed previous studies on HMB supplementation from online databases including PubMed, Web of Science, and Wiley Online Library.
RESULTS: Although studies suggest different results, this review found that HMB supplementation before or after exercise could have positive effects on body composition (muscle mass), exercise performance (strength and power, endurance), and recovery after muscle damage (creatine kinase and lactate dehydrogenase). In particular, HMB supplementation had a significant effect on resistance exercise, and in general, a daily dose of 3 g is recommended. However, the effects of combined HMB and creatine supplementation remain unclear.
CONCLUSIONS: HMB can be a useful and effective supplement for athletes with various purposes and for ordinary people who regularly exercise. Further research should investigate several limitations of HMB supplementation, as suggested in previous studies.

PURPOSE: Numerous studies claim that Taekwondo can effectively help obese children improve their physical fitness. In addition, Taekwondo might help prevent lifestyle diseases and metabolic syndrome caused by obesity. However, studies and reviews on the effectiveness of Taekwondo Poomsae are very few compared to those on Taekwondo Kyorugi. Based on previous reviews, this study aims to clarify the effect of Taekwondo Poomsae training on improving body composition, physical fitness, and blood composition of children and adolescents of different groups. Furthermore, the applicability of Taekwondo Poomsae training is to be determined.
METHODS: Two-hundred and two studies were searched via Korea electronic databases RISS, KISS, and DBPIA from March 1 to 3, 2021, and 22 of these were included in this review.
RESULTS: Our review confirms that Taekwondo Poomsae is effective in improving the physical condition of developing children and adolescents. However, we cannot assert that this sport is also an effective exercise therapy for special youth groups, such as those who are overweight, obese, or have a metabolic growth or development syndrome.
CONCLUSIONS: We suggest that sports implementers, Taekwando experts, coaches, and other sport professionals provide more Taekwondo Poomsae training programs suitable for physical and physiotherapeutic exercises for different ages and groups.

PURPOSE: The present review aimed to verify the meta-effects of resistance training (RT) or protein supplementation (PS) on usual gait speed (UGS) in postmenopausal women and the additive effect of RT and PS on UGS.
METHODS: A systematic literature search of PubMed/Medline and Web of Science (core collection) was performed from inception to December 31, 2021. Electronic search methods were used to identify 18 relevant randomized controlled trials. Meta-analyses of standardized mean difference (SMD) calculated using Hedges' g between RT and/or PS groups versus control groups were conducted using a random-effects model. The meta-effects are presented in a forest plot with a 95% confidence interval (CI).
RESULTS: The meta-analysis showed that RT significantly improved UGS (SMD, 0.40; 95% CI, 0.12-0.68; p=.006), while PS did not improve UGS (SMD, -0.17; 95% CI, -0.80 to 0.46; p=.601). A subgroup analysis indicated that there were significant increases in UGS after both 'RT-only intervention (SMD, 0.30; 95% CI, 0.01 to 0.59; p=.046)' and 'RT combined with balance training (BT) (SMD, 0.65; 95% CI, 0.17-1.13; p=.008)', while there was no significant increase in UGS after 'RT combined with power training (PT) (SMD, -0.08; 95% CI, -0.62 to 0.45; p=.765)'. There was no additive effect on UGS after RT combined with PS (SMD, -0.06; 95% CI, -0.36 to 0.24; p=.699).
CONCLUSIONS: This study revealed that RT significantly improved UGS in postmenopausal women, and adding BT to RT further improved UGS. In addition, there was no significant improvement in UGS after PS in postmenopausal women, and no additive effect on UGS after RT combined with PS.

PURPOSE: The purpose of this study is to investigate the physical activity (PA) and exercise barriers of stages 0-3 breast cancer survivors according to the Transtheoretical Model (TTM).
METHODS: This cross-sectional study that included data from a total of 295 breast cancer survivors (Age: 52.2±8.2 years, BMI: 23.5±3.3 kg/㎡), at Shinchon Severance Hospital, Seoul, Korea. The levels of PA and exercise barriers according to TTM were investigated using questionnaires.
RESULTS: PA participation increased in the TTM stage. The proportion of participants categorized according to TTM stage differed according to the time since cancer diagnosis: a higher proportion of participants were in pre-contemplation/contemplation within one year after diagnosis, while a higher proportion of participants were in maintenance after three three years since diagnosis. The five most prevalent exercise barriers were fatigue, low level of physical fitness, poor health, lack of interest, and tendency to be physically inactive. Fatigue is the most prevalent exercise barrier regardless of TTM stage, while most exercise barriers tend to reduce as participants are in the preparation/action and maintenance stages.
CONCLUSIONS: In this study, we confirmed that the participants in the maintenance stage were the most active, while the proportion of participants in the TTM stage varied according to time since diagnosis. Since PA and exercise barriers vary according to the TTM stage, the TTM stage may increase PA participation in breast cancer patients.

PURPOSE: This study aimed to determine the effects of bilateral and unilateral eccentric exercises on muscle damage and muscular physiological indices in healthy men.
METHODS: Using a randomized crossover design, nine adult males without musculoskeletal disorders were divided into a bilateral eccentric exercise group (BEG, n=9) and a unilateral eccentric exercise group (UEG, n=9). Bilateral and unilateral eccentric exercises involved five sets of six repetitions of the rhythm metronome speed eccentric contraction 3 seconds at 110% one repetition maximum (1RM) using bilateral of BEG and the dominant and non-dominant of UEG separated by four weeks, respectively. Muscle damage (flexed and extended ROM, CIR, and VAS) and muscular physiological indices (muscle activity, muscle fatigue, and muscle tone) were measured before, immediately after (0 hour), 24, 48, 72, and 96 hours following bilateral and unilateral eccentric exercises.
RESULTS: The flexed ROM, CIR, VAS, muscle activity, and muscle tone were significantly increased after both bilateral and unilateral eccentric exercises (p<.05, respectively). Extended ROM and muscle activity significantly decreased after both bilateral and unilateral eccentric exercises (p<.05, respectively). However, there was no significant interaction between side (S) and time and side (T×S).
CONCLUSIONS: These results showed that there was no difference in muscle damage and physiological indices after measuring and setting the 1RM muscle strength separated by bilateral and unilateral eccentric exercises.

PURPOSE: The purpose of this study is to investigate the effect of high-intensity interval training (HIIT), using real-time video application programs, on the body composition, blood lipids, cytokines, and quality of life (QOL) of over-weight men.
METHODS: The participants of this study were overweight men, aged < 45 years, who voluntarily applied to the online notices for this study. The men had a body mass index (BMI) >28. Twenty people participated in this experiment and were divided into two groups: a HIIT group (n=10) and a control group (n=10). Both groups were pre-examined to determine body composition, dual-energy X-ray absorptiometry, and QOL indices and also underwent blood tests. The HIIT group underwent high-intensity interval training for 8 weeks (twice a week and 35 minutes per day) using real-time video programs. The main exercise program for HIIT was 20 seconds high-intensity (85-90% HRmax) exercise followed by 30 seconds exercise at a 60% HRmax.
RESULTS: Comparison and analysis of the effects observed before and after the exercise revealed that the real-time online HIIT group showed reduced body fat (F=5.690, p=.028). Results of the blood tests showed that the high-density lipoprotein cholesterol (HDL; F=24.584, p=.001) was increased, while the low-density lipoprotein cholesterol (LDL; F=24.963, p=.001), triglycerides (TG; F=7.295, p=.015;), and total cholesterol (TC; F=14.934, p=.001) levels were decreased. No significant effects were observed on the insulin and c-reactive protein (CRP) levels. Finally, the QOL test results showed that the total score of the HIIT group had increased (F=190.815, p=.001).
CONCLUSIONS: Online HIIT is a useful method that aids in reducing fat levels in obese men and improving their blood lipid profile and QOL during the COVID-19 pandemic.

PURPOSE: To report the magnitude of changes in heart rate, muscle temperature, blood lactate concentration, blood pressure, and fatigue perception after treadmill jogging and running.
METHODS: Eleven healthy male adults (174±7 cm, 72±10 kg) visited the laboratory twice. After a 10-minute rest each visit, subjects performed a treadmill jog (maintaining a speed of 9 km/h at a 1% incline) or a treadmill run (initially 5 km/h at a 1% incline, belt speed, and incline increased by 1 km/h and 0.5% every minute; average speed of 9 km/h). Heart rate and muscle (gastrocnemius) temperature were recorded before, during, and after the treadmill jog/run. Blood lactate concentration, blood pressure, and fatigue perception were assessed before and after. The effect of the condition over time was analysed using parametric or nonparametric tests (p≤.05) with Cohen's d effect sizes.
RESULTS: There was a condition effect over time in heart rate (F1,30=22.16, p<.0001), blood lactate concentration (χ2=34.88, df=3, p<.0001), systolic blood pressure (F1,30=4.18, p=.05), and fatigue perception (F1,30=10.24, p=.003). Specifically, subjects who ran showed a higher heart rate (187 vs. 158 bpm, p<.0001, d=2.11), blood lactate concentration (11.4 vs. 3.8 mmol/L, p<.0001, d=3.39), systolic blood pressure (164 vs. 147 mmHg, p=.006, d=1.34), and fatigue perception (2.7 vs. 5.0 cm, p=.0005, d=1.46) than those who jogged. There was a time effect (F1,30=94.84, p<.0001) on muscle temperature, with a 1.5°C increase in muscle temperature after jogging/running (p<.0001, d=1.88).
CONCLUSIONS: While treadmill jogging and running induced a similar temperature increase in the gastrocnemius, running resulted in higher heart rate, blood lactate concentration, systolic blood pressure, and fatigue perception. These results can be used as a basis for planning warm-up protocols.

PURPOSE: The purpose of this study was to compare the gait variables and the relative risk of falling between elderly Korean women that fall and do not fall based on the walking speed during flat walking and in the presence of obstacles.
METHODS: The study included 148 women, aged 65 years or older (22 fallers, aged 75.05±5.38 years; 126 non-fallers, aged 71.80±5.14 years). The gait variables were measured in a space of 9 m×1 m, and obstacle walking was measured while crossing obstacles measuring, 5 cm and 30 cm. A t-test, correlation analysis, and logistic regression analysis were performed to compare the gait variables to determine if there was a fall and to analyze the relationship and the risk ratio of a fall at a walking speed.
RESULTS: Out of 148 participants, 22 participants (14.9%), fell while walking. During flat ground walking, right step length (p<.01) left step length (p<.05), and stride lengths (p<.01) were smaller in the faller group, while the stance phase (p<.01) and double-support time ratio (p<.05) were smaller in the non-faller group. In obstacle walking, slower walking speeds were observed for the 5-cm obstacles (p<.01) and 30-cm obstacles (p<.05) in the faller group. For the low-speed and medium-high speed groups, the odds ratio of the fall experience was 2.844 (1.125-7.191) (p<.05) for flat gait, 3.585 (1.354-9.491) (p<.05) for the 5 cm obstacle, and 4.877 (1.731- 13.742) (p<.01) for the 30 cm obstacle. As the height of the obstacle increased, the fall odds ratio increased.
CONCLUSIONS: In the faller group, the step and stride lengths were smaller during flat walking, and the walking speed of the obstacles was low. The low-speed group had a high falling experience odds ratio, and as the height of the obstacle increased, the falling experience odds ratio increased.

PURPOSE: This study aimed to examine the effect of the self-myofascial release technique conducted before weight training on functional movement and delayed onset muscle soreness (DOMS).
METHODS: The study subjects were divided into three groups: a control group (CON, n=8), an active stretching group (DS, n=8), and a self-myofascial release group (SMR, n=8). All three groups performed the same leg press exercise program for 30 minutes, twice a week for eight weeks. Active stretching and self-myofascial release techniques were conducted before exercise for 30 minutes. Body composition, 1RM, and functional movement screen (FMS) were tested before the 1st-week exercise and after the 4th- and 8th-week exercise training. The DOMS levels were assessed immediately after exercise and at 24, 48, and 72 hours post-exercise using the visual analog scale (VAS).
RESULTS: Body weight and body fat percentage showed a significant decrease (p<0.01), and muscle mass and 1RM increased with the exercise period (p<0.01). The FMS score differed between the groups (p<0.05), periods (p<0.01), and groups×periods (p<0.01). The FMS score was significantly higher in the SMR than in the CON group at the 4th- and 8th-week exercise. The exercise-induced VAS level peaked at 48 hours post-exercise in all groups and significantly decreased at 72 hours post-exercise in the SMR group.
CONCLUSIONS: These results indicate that self-myofascial release positively affects functional movements and effectively alleviates exercise-induced pain levels. Therefore, self-myofascial release techniques could be used as an effective warm-up strategy to improve physical function and relieve exercise-induced injury and muscle pain.