title: The metabolite beta-aminoisobutyric acid and physical inactivity among hemodialysis patients.
abstract: OBJECTIVE
  Physical inactivity is frequent in patients on hemodialysis (HD), and represents a reliable predictor of morbidity and mortality. Beta-aminoisobutyric acid (BAIBA) is a contraction-induced myokine, the plasma levels of which increase with exercise and are inversely associated with metabolic risk factors. The aim of this study was to ascertain whether physical inactivity and clinical parameters relate to plasma BAIBA levels in this patient population.
  
  
  METHODS
  Adult patients on HD were included, and the presence of physical inactivity was assessed. BAIBA levels were measured in these patients and in healthy individuals. We assessed barriers to physical activity, including 23 items regarding psychophysical and financial barriers. Body composition was assessed by bioimpedance and muscle strength by handgrip dynamometer. Nonparametric tests and logistic regression analyses were performed.
  
  
  RESULTS
  Forty-nine patients on HD were studied; 49% were physically active and 51% were inactive. Of the patients, 43 reported barriers to physical activity and 61% of inactive patients reported three or more barriers. BAIBA levels were lower in patients on HD with respect to controls (P < 0.001). Stratifying HD patients as active and inactive, both groups showed significantly lower BAIBA levels versus controls (P = 0.0005, P < 0.001, respectively). Nondiabetic patients on HD showed increased BAIBA levels compared with diabetic patients (P < 0.001). Patients on HD endorsing the two most frequent barriers showed lower BAIBA levels than those not reporting these barriers (P = 0.006). Active patients showed higher intracellular water (%) (P = 0.008), and active and inactive patients showed significant correlation between total body muscle mass and handgrip strength (P = 0.04, P = 0.005, respectively).
  
  
  CONCLUSIONS
  Physical inactivity is highly prevalent among patients on HD and BAIBA correlates with barriers to physical activity reported by inactive patients.
authors.affiliation: Department of Clinical Medicine, Sapienza University of Rome, Rome, Italy. Electronic address: alessio.molfino@uniroma1.it.
authors.forename: Alessio
authors.initials: A
authors.lastname: Molfino
authors.affiliation: Department of Clinical Medicine, Sapienza University of Rome, Rome, Italy.
authors.forename: Maria Ida
authors.initials: MI
authors.lastname: Amabile
authors.affiliation: Hemodialysis Unit, Fatebenefratelli 'Isola Tiberina' Hospital, Rome, Italy.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ammann
authors.affiliation: Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Farcomeni
authors.affiliation: Personalized Medicine Unit, Istituto Dermopatico dell'Immacolata-IRCCS, Rome, Italy.
authors.forename: Luana
authors.initials: L
authors.lastname: Lionetto
authors.affiliation: Neuroscience, Mental Health and Sense Organs Department, Advanced Molecular Diagnostics Unit, Sant'Andrea Hospital, Rome, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Simmaco
authors.affiliation: Department of Clinical Medicine, Sapienza University of Rome, Rome, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Lai
authors.affiliation: Department of Clinical Medicine, Sapienza University of Rome, Rome, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Laviano
authors.affiliation: Department of Clinical Medicine, Sapienza University of Rome, Rome, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Rossi Fanelli
authors.affiliation: Hemodialysis Unit, Fatebenefratelli 'Isola Tiberina' Hospital, Rome, Italy.
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Chiappini
authors.affiliation: Department of Clinical Medicine, Sapienza University of Rome, Rome, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Muscaritoli
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000621:Aminoisobutyric Acids / Q000097:blood*; D001823:Body Composition; D015992:Body Mass Index; D001835:Body Weight; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D015444:Exercise; D005260:Female; D018737:Hand Strength; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D053580:Muscle Strength; D006435:Renal Dialysis; D057185:Sedentary Behavior; D011795:Surveys and Questionnaires
chemical_list: D000621:Aminoisobutyric Acids; C033435:3-aminoisobutyric acid
keywords: Beta-aminoisobutyric acid (BAIBA); Body composition; Hemodialysis; Physical activity