Purpose: This study aimed to verify whether bioelectrical impedance vector analysis (BIVA) can support the clinical evaluation of sarcopenia in elderly individuals and evaluate the relationships between phase angle (PhA), physical performance, and muscle mass. Methods: The sample comprised 134 free-living elderly individuals of both sexes aged 69–91 years. Anthropometric parameters, grip strength, dual-energy X-ray absorptiometry findings, bioimpedance analysis results, and physical performance were also measured. The impedance vector distributions were evaluated in elderly individuals using BIVA. Results: BIVA revealed significant differences between the sarcopenia and non-sarcopenia groups (both sexes). The sarcopenia group had a significantly lower PhA than the non-sarcopenia group in both sexes (p < 0.05). PhA was significantly correlated with age, appendicular skeletal muscle (ASM), handgrip strength (HGS), and muscle quality in both sexes and significantly correlated with ASM/Height² and physical performance in males. Conclusion: BIVA can be used as a field assessment method in elderly Koreans with sarcopenia. PhA is a good indicator of muscle strength, muscle quality, and physical performance in males. These methods can help diagnose sarcopenia in elderly individuals with reduced mobility.

ACTN3 R577X and ACE I/D polymorphisms are associated with endurance exercise ability. This case–control study explored the association of ACTN3 and ACE gene polymorphisms with elite pure endurance in Korean athletes, hypothesizing that individuals with both ACTN3 XX and ACE II genotypes would exhibit superior endurance. We recruited 934 elite athletes (713 males, 221 females) and selected 45 pure endurance athletes (36 males, 9 females) requiring “≥90% aerobic energy metabolism during sports events”, in addition to 679 healthy non-athlete Koreans (361 males, 318 females) as controls. Genomic DNA was extracted and genotyped for ACTN3 R577X and ACE I/D polymorphisms. ACE ID (p = 0.090) and ACTN3 RX+XX (p = 0.029) genotype distributions were significantly different between the two groups. Complex ACTN3-ACE genotypes also exhibited significant differences (p = 0.014), with dominant complex genotypes positively affecting endurance (p = 0.039). The presence of RX+II or XX+II was associated with a 1.763-fold higher likelihood of possessing a superior endurance capacity than that seen in healthy controls (90% CI = 1.037–3.089). Our findings propose an association of combined ACTN3 RX+XX and ACE II genotypes with enhanced endurance performance in elite Korean athletes. While causality remains to be confirmed, our study highlights the potential of ACTN3-ACE polymorphisms in predicting elite endurance.

Dietary supplements are commonly employed to provide additional nutritional support for athletes. In taekwondo, there is a need for evidence-based analyses to evaluate the effects of dietary supplements on training outcomes, competitive performance, and injury recovery. Taekwondo primarily relies on oxidative metabolism, yet decisive lower-limb attacks depend on non-oxidative pathways. A comprehensive literature search was conducted in PubMed, Scopus, and Web of Science databases in November 2024, utilizing keywords including ‘Dietary Supplements’, ‘Supplements’, ‘Food Supplementations’, and ‘Taekwondo’. Of the 203 articles identified, 26 met the inclusion criteria, collectively assessing the impact of 14 different dietary supplements. Among these studies, eight provided strong evidence that acute ingestion of 3–5 mg/kg of caffeine significantly enhanced athletes’ physical performance and psychological well-being. However, the ergogenic effects of the compound Fufang Ejiaojiang, creatine, sodium bicarbonate, beetroot, vitamins, and long beans require further investigation to validate their efficacy. Additionally, dietary supplements, such as amino acids, turmeric powder, ginger, spirulina, octacosanol, nucleotides, and yogurt, can reduce fatigue, supporting injury recovery, and boosting immune function, although current evidence remains insufficient. Future research should pay closer attention to reporting adverse reactions linked to dietary supplements. Doing so would provide coaches and athletes with more reliable safety information, supporting safer choices and reducing potential health risks.

Sodium bicarbonate is used as an ergogenic supplement to enhance people’s performances in various exercises. This study aimed to evaluate the effects of intestinal delivery of sodium bicarbonate on bicarbonate absorption and associated side effects in an experimental human trial. After preparing and assessing enteric-coated and uncoated sodium bicarbonate tablet formulations, pharmacokinetic analysis and gastrointestinal symptom tests were performed after oral administration in the human body. The dose required to increase blood bicarbonate concentration over 5 mmol∙L⁻¹ for the purpose of improving performance during high-intensity exercise was also determined. Enteric-coated tablet formulation protects sodium bicarbonate under acidic conditions and releases bicarbonate in the intestine. Enteric-coated tablet formulation also reduced the oral dose required to achieve a blood bicarbonate concentration over 5 mmol∙L⁻¹ from 300 mg∙kg⁻¹ of uncoated tablet formulation to 225 mg∙kg⁻¹. Gastrointestinal discomfort was significantly decreased for the group given 225 mg∙kg⁻¹ enteric-coated tablets compared to that given 300 mg∙kg⁻¹ uncoated tablets. These results suggest that enteric-coated tablet formulation could reduce the oral dose required in order to achieve a blood bicarbonate concentration over 5 mmol∙L⁻¹ by 25%, from 300 mg∙kg⁻¹ to 225 mg∙kg⁻¹, along with its ability to reduce gastrointestinal discomfort associated with the dosage.

Soccer, as a high-intensity sport, places significant physical demands on athletes and is associated with a high risk of injury. Electrical muscle stimulation (EMS), a training and rehabilitation technology, has gained attention for its potential benefits in sports settings. This systematic review, conducted under the PRISMA guidelines, rigorously assessed the effectiveness of EMS in improving muscle strength, promoting post-exercise recovery, and facilitating injury rehabilitation among soccer players. A comprehensive search of the PubMed, Scopus, and Web of Science databases identified 10 studies meeting the inclusion criteria. Among these, six studies demonstrated a significant improvement in athletic performance following local or whole-body EMS application. Four studies provided evidence supporting EMS’s efficacy in enhancing post-exercise recovery and reducing recovery time after injuries, with observed reductions in recovery time. However, the majority of the included studies were not double-blind, which limits the strength of the evidence. None of the included studies reported EMS-related adverse effects. Overall, the current results suggest that EMS may be a useful adjunct to improve athletic performance and facilitate recovery in soccer players. This review offers actionable insights for coaches and athletes regarding the safe and effective application of EMS in soccer training and rehabilitation programs.

Background/Objectives: Body mass index (BMI) cannot distinguish fat mass (FM) from fat-free mass (FFM). The fat-free mass index (FFMI = FFM/height²) and fat mass index (FMI = FM/height²) decompose BMI into lean and fat components. We aimed to establish the first nationally representative, BIA-based FFMI and FMI reference values for Korean adults, visualize body composition trajectories, and classify obesity subtypes using the body composition chart. Methods: Cross-sectional data from 10,140 participants (4508 men, 5632 women; aged 10–80 years) from KNHANES IX (2022–2023) were analyzed. Multifrequency BIA (InBody 970) measured FFM and FM. Obesity subtypes (%BF ≥ 25% men, ≥35% women) were classified as underlean (FFMI < P5), proportional (P5–P95), or heavy (>P95) relative to an 18–59-year-old reference. Results: In men, FFMI peaked at 19.1 kg/m² (30–49 years), declining 9.7% by 70–80 years, while FMI remained stable. In women, FMI increased 44% with stable FFMI. Underlean obesity in men rose from 0.7% (30–39 years) to 17.4% (70–80 years), undetected by BMI or waist circumference. Conclusions: These reference values and body composition chart provide practical tools for identifying underlean obesity and assessing body composition beyond BMI in Korean adults.