Effects of Combined Creatine Monohydrate and β-Hydroxy-β-Methylbutyrate Supplementation on Body Composition, Physical Performance, Quality of Life, Oxidative Stress, and Inflammation in Physically Active Older Individuals Who Underwent a Comprehensive Fitness Program: A Randomized Crossover Clinical Trial

Sarcopenia (SAR) is the loss of muscle strength and mass caused by aging. It is accompanied by a progressive decline in physical and cognitive abilities, increasing the risk of falls. This loss of muscle mass leads to pathophysiological changes at the neuromuscular and tendon levels as a consequence, among others, of alterations in the balance between protein synthesis and degradation, inflammation (INF), or alterations in the anabolic/catabolic state (ACS). These alterations are caused by oxidative stress (OS), when reactive oxygen species-toxic metabolites produced by cells using oxygen-exceed the defensive capacity of the antioxidant system. Therapeutic strategies to modulate SAR are based on exercise and nutrition programs. Multicomponent physical exercise programs have shown improvements in parameters related to sarcopenia. Likewise, the use of nutritional supplements such as creatine (CRE) has demonstrated improvements in muscle function in older adults. CRE may reduce INF and OS in the general population. On the other hand, beta-hydroxy-beta-methylbutyrate (HMB) also appears to improve muscle function in older adults by promoting myogenesis. However, the effects of these supplements in older adults have only been observed when used in isolation. In this regard, our research team observed that a 10-week regimen combining 3 g/day of CRE + 3 g/day of HMB (CRE-HMB) improved muscle recovery (better ACS) and physical performance in athletes subjected to high muscle wear. However, to date, it has not been determined whether this combination improves muscle function, OS, INF, and ACS in women with SAR. Therefore, the working hypothesis is that the CRE-HMB combination could improve muscle function and physical performance, as well as OS, INF, and ACS in individuals with high muscle loss, such as those with SAR. Thus, a randomized double-blind crossover study is proposed to analyze the effect of 12 weeks-6 weeks of intervention + 3 weeks of washout + 3 weeks of intervention-of co-supplementation with 3 g/day of CRE + 3 g/day of HMB (CRE-HMB), combined with 4 sessions/week of multicomponent physical exercise, on muscle function, OS, INF, and ACS in 40 physically active men and women over 60 years of age. These 40 participants will be divided into two groups of 20 (20 in the placebo group and 20 in the CRE-HMB group). At the assessment points (baseline, at 6 weeks, after the 3-week washout period, and after another 6 weeks), body composition, nutritional intake, muscle strength, and performance tests will be evaluated. Blood samples will also be collected to determine biochemical markers of OS, INF, and ACS. It is expected that CRE-HMB co-supplementation for 6 + 6 weeks, together with multicomponent physical exercise, in physically active older adults will improve muscle strength, muscle mass, and performance. Additionally, improvements in OS, INF, and ACS levels are anticipated.