title: Relationship between exercise capacity and urinary liver-type fatty acid-binding protein in middle-aged and older individuals.
abstract: BACKGROUND
  The underlying mechanism linking the decline in exercise capacity with renal dysfunction remains unclear. Urinary liver-type fatty acid-binding protein (L-FABP) levels reflect the degree of peritubular capillary blood flow, an important factor for renal dysfunction with aging. The aim of this study was to examine the relationship between exercise capacity and urinary L-FABP levels.
  
  
  METHODS
  This was a cross-sectional study of 187 middle-aged and older individuals (aged 50-83 years) without chronic kidney disease (CKD). We assessed urinary L-FABP levels, peak oxygen consumption ([Formula: see text]), and grip strength.
  
  
  RESULTS
  Urinary L-FABP levels inversely correlated with both [Formula: see text] (rs= -0.349) and grip strength (rs= -0.485). When the participants were divided into four groups according to the median values of aerobic fitness and muscular strength ([Formula: see text] and grip strength), urinary L-FABP levels were the highest in participants with lower levels of aerobic fitness and muscular strength (2.95 ± 1.43 μg/g creatinine) and the lowest in the participants with higher levels of aerobic fitness and muscular strength (1.33 ± 0.76 μg/g creatinine). The difference between the two groups was significant (P < 0.001).
  
  
  CONCLUSIONS
  Our results demonstrate that both [Formula: see text] and grip strength were inversely associated with urinary L-FABP levels in middle-aged and older individuals without CKD. This suggests that a decline in exercise capacity is associated with a reduction in peritubular capillary blood flow, providing a novel insight into the underlying mechanism linking the decline in exercise capacity to the development of renal dysfunction.
authors.affiliation: Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.
authors.forename: Keisei
authors.identifier: http://orcid.org/0000-0001-6001-578X
authors.initials: K
authors.lastname: Kosaki
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine, St. Marianna University School of Medicine, Kanagawa, Japan.|Department of Anatomy, St. Marianna University School of Medicine, Kanagawa, Japan.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Kamijo-Ikemori
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine, St. Marianna University School of Medicine, Kanagawa, Japan.|CMIC Company, Limited, Tokyo, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sugaya
authors.affiliation: Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Tanahashi
authors.affiliation: Faculty of Health and Sport Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8574, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kumagai
authors.affiliation: Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Sawano
authors.affiliation: Faculty of Health and Sport Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8574, Japan.
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Akazawa
authors.affiliation: Faculty of Sports and Health Science, Fukuoka University, Fukuoka, Japan.
authors.forename: Song-Gyu
authors.initials: SG
authors.lastname: Ra
authors.affiliation: JCHO Tokyo Takanawa Hospital, Tokyo, Japan.
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Kimura
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine, St. Marianna University School of Medicine, Kanagawa, Japan.
authors.forename: Yugo
authors.initials: Y
authors.lastname: Shibagaki
authors.affiliation: Faculty of Health and Sport Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8574, Japan. maeda@taiiku.tsukuba.ac.jp.
authors.forename: Seiji
authors.initials: S
authors.lastname: Maeda
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000652:urine; D015415:Biomarkers / Q000652:urine; D002196:Capillaries / Q000503:physiopathology; D003430:Cross-Sectional Studies; D017079:Exercise Tolerance; D050556:Fatty Acid-Binding Proteins / Q000652:urine*; D005260:Female; D018737:Hand Strength; D006304:Health Status; D006801:Humans; D007668:Kidney / Q000098:blood supply*; D007674:Kidney Diseases / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology / Q000652:urine; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D012079:Renal Circulation; D012307:Risk Factors; D013997:Time Factors
chemical_list: D015415:Biomarkers; C493319:FABP1 protein, human; D050556:Fatty Acid-Binding Proteins
keywords: Aerobic fitness; Muscular strength; Peritubular capillary blood flow