Introduction
In humans, muscle mass decreases after its peak in the third decade of life [1]. Muscle mass is important for physical and metabolic fitness regulation. The development of sarcopenia is an important risk factor for the development of frailty, loss of independence and physical disability in the elderly and is associated with shorter survival in critically ill patients [2]. In the 8th decade, men and women can lose about 7 and 3.8 kg of muscle mass, respectively, with increased intra-abdominal fat [3].
In this context, the number of disabilities due to age is expected to double by 2060. Muscle mass is important for physical fitness and metabolic regulation [4]. In this scenario, the development of sarcopenia is an important risk factor for the development of frailty, loss of independence and physical disability in the elderly and is associated with lower survival in critically ill patients. The pathophysiology of sarcopenia is multifactorial and may be influenced by reduced caloric intake, neurodegenerative diseases, intracellular oxidative stress, hormonal disorders, and others. In this sense, the decline in fat-free mass correlates with the decline associated with the age of growth hormone (GH) secretion. Thus, GH secretagogue (Ibutamoren - MK-677) as the first orally active ghrelin mimetic may increase pulsatile GH secretion in the elderly [5].
Therefore, the present study aimed to determine whether oral MK-677 in healthy elderly would increase GH and insulin-like growth factor I (IGF-I) levels, prevent the decline of muscle mass, and decrease abdominal visceral fat (AVF) with acceptable tolerability.