title: Changes in the serum cartilage biomarker levels of healthy adults in response to an uphill walk.
abstract: BACKGROUND
  To prevent long-term unfavourable consequences to the articular cartilage of weight-bearing joints, serum biomarkers can be used to identify optimum loading of activities. This study aimed to investigate the circulation pattern of serum cartilage biomarkers in healthy adults in response to an uphill walk.
  
  
  METHODS
  This study recruited 58 healthy participants for the experimental group and 24 matched participants for the control group. Participants in the experimental group walked continuously for 14 km on a pathway with a 5.97° incline, while participants from the control group walked on a horizontal pathway. Serum was collected from both groups preactivity (i.e. T1), immediately after activity (i.e. T2) and 24 hours after T1 (i.e. T3). The serum cartilage oligomeric matrix protein (COMP), chondroitin sulfate-WF6 (WF6) and hyaluronic acid (HA) levels at each time point were quantified using enzyme-linked immunosorbent assays, and the results analysed.
  
  
  RESULTS
  Both groups shared similar demographic characteristics and activity duration. At T2, the serum COMP level of the experimental group was significantly higher than that of the control group, but the serum HA level of the experimental group was significantly lower than that of the control group. No significant difference between the serum WF6 levels of the experimental and control groups was observed at T2.
  
  
  CONCLUSIONS
  Increasing levels of serum COMP demonstrate articular cartilage susceptibility to the increasing load. An unsustainable, high serum COMP level and an undetectable change in WF6 level were considered to be a reversible physiological change of the cartilage. A change in ser um HA level could be related to intensive physical activity and dynamic clearance rather than a change in cartilage structure.
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, Chiang Mai University, 239 Huay Kaew Road, Suthep, Muang, Chiang Mai 50200, Thailand. dumnoensun@hotmail.com.
authors.forename: Dumnoensun
authors.initials: D
authors.lastname: Pruksakorn
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, Chiang Mai University, 239 Huay Kaew Road, Suthep, Muang, Chiang Mai 50200, Thailand. dumnoensun@hotmail.com.
authors.forename: Premchai
authors.initials: P
authors.lastname: Tirankgura
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, Chiang Mai University, 239 Huay Kaew Road, Suthep, Muang, Chiang Mai 50200, Thailand. dumnoensun@hotmail.com.
authors.forename: Sirichai
authors.initials: S
authors.lastname: Luevitoonvechkij
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, Chiang Mai University, 239 Huay Kaew Road, Suthep, Muang, Chiang Mai 50200, Thailand. dumnoensun@hotmail.com.
authors.forename: Samatchai
authors.initials: S
authors.lastname: Chamnongkich
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, Chiang Mai University, 239 Huay Kaew Road, Suthep, Muang, Chiang Mai 50200, Thailand. dumnoensun@hotmail.com.
authors.forename: Nantawit
authors.initials: N
authors.lastname: Sugandhavesa
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, Chiang Mai University, 239 Huay Kaew Road, Suthep, Muang, Chiang Mai 50200, Thailand. dumnoensun@hotmail.com.
authors.forename: Taninnit
authors.initials: T
authors.lastname: Leerapun
authors.affiliation: Department of Orthopaedics, Faculty of Medicine, Chiang Mai University, 239 Huay Kaew Road, Suthep, Muang, Chiang Mai 50200, Thailand. dumnoensun@hotmail.com.
authors.forename: Peraphan
authors.initials: P
authors.lastname: Pothacharoen
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood*; D064236:Cartilage Oligomeric Matrix Protein / Q000097:blood; D002358:Cartilage, Articular / Q000378:metabolism*; D002809:Chondroitin Sulfates / Q000097:blood; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D006820:Hyaluronic Acid / Q000097:blood; D008297:Male; D013997:Time Factors; D016138:Walking; D055815:Young Adult
chemical_list: D015415:Biomarkers; D064236:Cartilage Oligomeric Matrix Protein; D002809:Chondroitin Sulfates; D006820:Hyaluronic Acid; C577553:TSP5 protein, human