Effects of Co-Ingestion of β-Hydroxy-β-Methylbutyrate and L-Arginine α-Ketoglutarate on Jump Performance in Young Track and Field Athletes

International society of sports nutrition position stand: β-hydroxy-β-methylbutyrate (HMB)

Position Statement: The International Society of Sports Nutrition (ISSN) bases the following position stand on an analysis of the literature regarding the effects of β-Hydroxy-β-Methylbutyrate (HMB). The following 12 points have been approved by the Research Committee of the Society: 1. HMB is a metabolite of the amino acid leucine that is naturally produced in both humans and other animals. Two forms of HMB have been studied: Calcium HMB (HMB-Ca) and a free acid form of HMB (HMB-FA). HMB-FA appears to lead to increased appearance of HMB in the bloodstream when compared to HMB-Ca, though recent results are mixed. 2. The available safety/toxicity data suggest that chronic HMB-Ca and HMB-FA consumption are safe for oral HMB supplementation in humans up to at least one year. 3. There are no negative effects of HMB-Ca and HMB-FA on glucose tolerance and insulin sensitivity in humans. There may be improvements in glucose metabolism in younger adults. 4. The primary mode of action of HMB appears to be through its dual mechanism to enhance muscle protein synthesis and suppress muscle protein breakdown. HMB's activation of mTORC1 is independent of the leucine-sensing pathway (Sestrin2-GATOR2 complex). 5. HMB may help reduce muscle damage and promote muscle recovery, which can promote muscle growth/repair. HMB may also have anti-inflammatory effects, which could contribute to reducing muscle damage and soreness. 6. HMB consumption in close proximity to an exercise bout may be beneficial to increase muscle protein synthesis and attenuate the inflammatory response. HMB can provide a beneficial physiological effect when consumed both acutely and chronically in humans. 7. Daily HMB supplementation (38 mg/kg body weight) in combination with exercise training may improve body composition through increasing lean mass and/or decreasing fat mass with benefits in participants across age, sex, and training status. The most pronounced of these improvements in body composition with HMB have been observed in studies with robust resistance training programs and dietary control. 8. HMB may improve strength and power in untrained individuals, but its performance benefits in trained athletes are mixed and increase with an increase in study duration (>6 weeks). HMB's beneficial effects on athletic performance are thought to be driven by improved recovery. 9. HMB supplementation appears to potentially have a positive impact on aerobic performance, especially in trained athletes. The mechanisms of the effects are unknown. 10. HMB supplementation may be important in a non-exercising sedentary and aging population to improve muscle strength, functionality, and muscle quality. The effects of HMB supplementation with exercise are varied, but the combination may have a beneficial effect on the treatment of age-associated sarcopenia under select conditions. 11. HMB may be effective in countering muscle disuse atrophy during periods of inactivity due to illness or injury. The modulation of mitochondrial dynamics and lipid metabolism by HMB may be a potential mechanism for preventing disuse atrophy and aiding rehabilitation beyond HMB's effects on rates of muscle protein synthesis and degradation. 12. The efficacy of HMB in combination with certain nutrients may be enhanced under select conditions.

Impact of Alpha-Ketoglutarate on Skeletal Muscle Health and Exercise Performance: A Narrative Review

AKG, a central metabolite in the Krebs cycle, plays a vital role in cellular energy production and nitrogen metabolism. This review explores AKG's potential therapeutic applications in skeletal muscle health and exercise performance, focusing on its mechanisms for promoting muscle regeneration and counteracting muscle atrophy. A literature search was conducted using the PubMed, Web of Science, and Scopus databases, yielding 945 articles published up to 31 October 2024. Of these, 112 peer-reviewed articles met the inclusion criteria and formed the basis of this review. AKG supports muscle recovery by stimulating muscle satellite cells (MuSCs) and macrophage polarization, aiding muscle repair and reducing fibrosis. Additionally, AKG shows promise in preventing muscle atrophy by enhancing protein synthesis, inhibiting degradation pathways, and modulating inflammatory responses, making it relevant in conditions like sarcopenia, cachexia, and injury recovery. For athletes and active individuals, AKG supplementation has enhanced endurance, reduced fatigue, and supported faster post-exercise recovery. Despite promising preliminary findings, research gaps remain in understanding AKG's long-term effects, optimal dosage, and specific pathways, particularly across diverse populations. Further research, including large-scale clinical trials, is essential to clarify AKG's role in muscle health and to optimize its application as a therapeutic agent for skeletal muscle diseases and an enhancer of physical performance. This review aims to provide a comprehensive overview of AKG's benefits and identify future directions for research in both clinical and sports settings.

Fatigue in Covid-19 survivors: The potential impact of a nutritional supplement on muscle strength and function

BACKGROUND

Fatigue with reduced tolerance to exercise is a common persistent long-lasting feature amongst COVID-19 survivors. The assessment of muscle function in this category of patients is often neglected.

AIM

To evaluate the potential impact of a daily supplementation based on amino acids, minerals, vitamins, and plant extracts (Apportal®) on muscle function, body composition, laboratory parameters and self-rated health in a small group of COVID-19 survivors affected by fatigue.

METHODS

Thirty participants were enrolled among patients affected by physical fatigue during or after acute COVID-19 and admitted to the post-COVID-19 outpatient service at Fondazione Policlinico Gemelli in Rome between 1st March 2021 and 30th April 2021. All participants were evaluated at first visit (t0) and at control visit (t1), after taking a daily sachet of Apportal® for 28 days. Muscle function was analyzed using hand grip strength test, exhaustion strength time and the number of repetitions at one-minute chair stand test. Body composition was assessed with bioelectrical impedance analysis (BIA). Laboratory parameters, including standard blood biochemistry and ferritin levels, were evaluated at the first visit and during the control visit. A quick evaluation of self-rated health, before COVID-19, at t0 and t1, was obtained through a visual analogue scale (VAS).

RESULTS

Participants aged 60 years and older were 13 (43%). Females represented the 70% of the study sample. Participants hospitalized for COVID-19 with low-flow oxygen supplementation represented the 43.3% of the study sample while 3.3% received noninvasive ventilation (NIV) or invasive ventilation. Hand grip strength improved from 26.3 Kg to 28.9 Kg (p < 0.05) at t1 as compared to t0. The mean time of strength exhaustion increased from 31.7 s (sec) at t0 to 47.5 s at t1 (p < 0.05). Participants performed a higher number of repetitions (28.3 vs. 22.0; p < 0.05) during the one-minute chair stand test at t1 as compared to t0. A trend, although not significant, in reduction of ferritin levels was found after nutritional supplementation (94.4 vs. 84.3, respectively; p = 0.01). The self-rated health status increased by at least 13 points (t0, mean 57.6 ± 5.86; t1, mean 71.4 ± 6.73; p < 0.05).

CONCLUSIONS

After 28 days of nutritional supplementation with Apportal® in COVID-19 survivors affected by fatigue with reduced tolerance to exercise, we found a significant improvement in means of muscle strength and physical performance, associated with enhancement of self-rated health status between t0 and t1.