Intracellular Water Content in Lean Mass as an Indicator of Muscle Quality in an Older Obese Population

Abstract

Background: In aged populations, muscle strength depends more on muscle quality than on muscle quantity, while all three are criteria for the diagnosis of sarcopenia. Intracellular water content (ICW) in lean mass (LM) has been proposed as an indicator of muscle quality related to muscle strength in older people. Objectives: To evaluate the relationship between the ICW/LM ratio, muscle strength and indicators of functional performance in obese older adults, and to assess the value of the ICW/LM ratio as an indicator of muscle quality. Methodology: Design: cross-sectional study. Population: persons aged 65–75 years with a body mass index of 30–39 kg/m2. ICW and LM were estimated by bioelectrical impedance. Hand grip, gait speed, unipedal stance test, timed up-and-go (TUG) test, Barthel score and frailty (Fried criteria) were assessed. Sarcopenia was established according to EWGSOP2 criteria. Results: Recruited were 305 subjects (66% women), mean age 68 years. The ICW/LM ratio correlated with the TUG test, gait speed and grip strength, and was also associated with sex, the unipedal stance test and frailty. Independently of age, sex and muscle mass, the ICW/LM ratio was related with gait speed, the TUG test and unipedal stance capacity. One person (0.3%) had sarcopenia defined as low muscle strength and low muscle mass, while 25 people (8.2%) had sarcopenia defined as low muscle strength and poor muscle quality (ICW/LM). With this last definition, sarcopenia was related to frailty, gait speed and the TUG test. Conclusions: ICW content in LM could be a useful muscle quality indicator for defining sarcopenia. However, more studies are required to confirm our findings for other populations.

Low intracellular water and incident cognitive impairment in chronic hemodialysis patients

“…32 Two recent studies reinforced the idea that low-grade chronic cell dehydration might play a role in loss of muscle function; high ICW content of myocytes, independent of muscle mass, had been associated with better functional performance and a lower frailty risk in aged populations. 11,12 Goulet et al also suggested that acute dehydration of 1% of body weight in healthy 60-75 years old men could affect muscle endurance, power and strength. 33 Moreover, the correlation between ICW and muscle strength has also been observed in young adult athletes.…”

“…Intracellular water (ICW) is a biomarker of cell hydration status and muscle mass. In elderly individuals with similar muscle mass, those with lower ICW had a worse functional performance and a higher frailty risk, suggesting a harmful effect of cell dehydration, independently of muscle mass 11–13 . As with the age‐related ICW decline, ICW significantly decreases over time in HD patients.…”

Association between muscle mass quantity and quality and muscle strength in adults with obesity

“…The ICW/LM ratio is based on the hypothesis of reduced muscle cells or reduced hydration, which is plausible in the obese population. Regardless of the reason, the altered cell volume determined by ICW seems to be an important metabolic signal that regulates cell and muscle functions [11]. However, little is known about muscle quality indicators, including the ICW/LM ratio in the adult population with obesity.…”

“…The association between the amount of muscle mass and muscle strength has been made evident in the literature [8,9]. However, recent studies suggest that muscle quality, among other aspects, can better explain the decline in muscle strength levels [10,11]. Muscle quality is de ned as the capacity to generate force relative to the volume of contractile tissue [12].…”

“…Muscle quality is de ned as the capacity to generate force relative to the volume of contractile tissue [12]. In this sense, some studies point to intracellular water (ICW) and the ICW/lean mass (LM) ratio as indicators of muscle quality [10,11] since water makes up most of the LM [10]. In fact, older adults, women, and individuals with obesity have less LM and, consequently, a lower amount of total body water (TBW) [10].…”