Serum Cartilage Oligomeric Matrix Protein Levels After 12 Weeks of Different Exercises
Condition: Osteoarthritis; Articular Cartilage Disorder of Knee; Degenerative Lesion of Articular Cartilage of Knee
MeSH terms: Cartilage Diseases
Study type: Interventional
Phase: Early Phase 1

Summary: 
      Acute effects of physical exercise on the deformational behavior of articular cartilage and
      changes in cartilage oligomeric matrix protein (COMP) are definite. However, conclusive
      positive effects of fitness exercise on functional adaptation of articular cartilage have not
      been proved.Therefore, in this parallel-group randomized control trial, the investigators
      tested the hypothesis that adequate amount of physical exercise with enough impact would be
      able to stimulate the functional behavior of articular cartilage.

      The investigators evaluated 44 healthy males for their physical fitness levels and their
      blood samples were obtained before, immediately after and 0.5 h after a 30-min walking
      exercise. Thereafter, participants were assigned to the running, the cycling, the swimming
      and the control groups. At the end of 12-weeks of intervention, same measurement procedures
      were applied. Mixed repeated-measures ANOVA design was used for statistics. (Level of
      evidence: 2)
    

Detailed description: 
      Design

      A prospective, parallel-group randomized control trial was designed. Mustafa Kemal University
      (MKU) Ethical Board approved the study (B.30.2.MKU.0.01.01.00/255). The exact nature of the
      study was explained to participants and they were asked to sign a written consent. The tests
      were carried out at Middle East Technical University Medical Center, Ankara, Turkey between
      January and June 2008. The independent variables were groups (n=4) and time (n=2). The
      dependent variable was serum cartilage oligomeric matrix protein (COMP) levels measured at
      three phases of exercise: before (Recovery), immediately after (Fatigue), and 30-min after
      the exercise (Regeneration). Participants were subjected to the following tests prior to and
      at the end of the intervention period: body mass index (BMI), isokinetic leg muscle strength,
      maximum oxygen consumption (VO2max) and serum COMP levels.

      Participants

      115 applicants volunteered to take part in this study. Eligibility screening was performed
      according to inclusion criteria. From 104 eligible applicants, 48 healthy, sedentary male
      university students aged between 18 to 25 years old (Mage = 21.8±1.9) were selected by a
      simple drawing. However, study completed with 44 participants, because of 4 dropouts.
      Participants were randomly assigned in 1:1:1:1 ratio to parallel groups, three exercise
      groups (swimming, cycling and running) and one control. In order to have a random allocation,
      each participant received a number unknown to researchers which was written on a piece of
      paper and then drawn from a box that allowed to assign individuals to the control and
      exercise groups. Baseline blood samples were stored in -80°C and they were not analyzed
      during participants' allocation. Exclusion criteria, surveyed by a questionnaire, were:
      osteoarthritis, rheumatoid arthritis or other inflammatory joint disease, intra-articular
      steroid injection, mal-alignment of the knees (varus/valgus) larger than 15°, and recent
      (within six months) fracture of lower extremity. Active athletes and volunteers with previous
      sports background were not included. During the intervention period, one participant was
      excluded from the study because of sudden kidney disease and another one decided to withdraw
      from further participation. In addition, two participants were excluded from the study before
      biochemical analyses since one subject from running group didn't meet minimum requirement of
      75% of exercise session attendance, and one subject from control group didn't complete the
      posttests. Descriptive data of participants are presented in.

      Interventions

      After the first measurements, participants were randomly and equally assigned to the
      swimming, the running, the cycling and the control groups. All exercise groups participated
      in sessions of 40-min per day, three days per week, for a period of 12 weeks. Each session
      began with a five minutes warm-up, continued with a main set of 30-min exercise at their
      individual target heart rate zone (60-70% of heart rate reserve), and finished with a five
      minute cool-down period. The individual target heart rate zone was determined according to
      the Guidelines for Exercise Testing and Prescription of American College of Sport Medicines
      [1]. Swimming exercises composed of front crawl swimming and kicking drills. During the main
      sets, the participants performed front-crawl swimming at their individual heart rate zones
      which were determined by the Karvonen formula [2]. Cyclers exercised between 60-80 repetition
      per minute (RPM) on an ergometer (Monark E 834, Varberg, Sweden), which was adjusted for each
      individual in order to maintain the target heart rate zone. The running group participants
      exercised on a treadmill with a 1.5 % incline. The speed of the treadmill was determined
      according to individual heart rate zone. Throughout the 12 weeks of training, Heart Rate
      Reserves (HRR) was held constant (60-70%) while the speed increased according to individual
      progression. Individuals of the control group were instructed not to participate in any
      organized or structured exercise during the 12 weeks of intervention.

      Physical and Physiological Measurements

      Body Mass Index was calculated as the ratio of body weight to height square (Heyward &
      Stolarczyk 1996). VO2max was measured by the standard Bruce Protocol (Bruce, Kusumi & Hosmer
      1973) on a Jager LE 200 CE (Hochberg, Germany) treadmill. Measurements were performed with
      the VIASYS Healthcare ergospirometry line using the MasterScreen CPX (Wuerzburg, Germany)
      device. Results were presented in ml/kg/min (milliliters of oxygen per kilogram of body
      weight per minute). Isokinetic quadriceps strength was recorded with the Biodex System
      Dynamometer (Biodex Medical Inc, Shirley, NY). Participants were placed in a comfortable
      position that allowed unrestricted motion of the knee from 90 degrees of flexion to terminal
      extension on a bicycle ergometer, and asked to warm-up for five minutes at which point they
      stretched their extremities. Before the test trials, participants were instructed to perform
      their maximum efforts. Then five isokinetic concentric knee flexion and extension at 60°/sec
      with their dominant legs were recorded. After, peak torque to body weight ratio (PT/BW) was
      measured.

      Blood Sampling and Enzyme-Linked Immunosorbent Assay (ELISA) Procedures

      Blood obtaining procedures were modified from Mundermann et al. [3]. Participants were asked
      to limit their physical activity 48 hours prior to the experiment. On the day of the
      experiment, participants made their breakfast within one hour after waking up and the
      experiment started two to three hours after breakfast. In addition, participants were seated
      on a chair for 15-min immediately before the experiment. Five-milliliter blood samples were
      obtained by a certified research nurse from the same antecubital vein immediately before,
      immediately after, and 0.5 hours after a 30-min walking exercise. During the walking exercise
      of the test protocol, participants walked at a pace of 5 km/h on a treadmill with 1.5 %
      incline. After the walking exercise, participants sat on an office chair for 30-min and were
      asked to rest.

      Blood sample collection and storage procedures were described previously [4]. Venous blood
      samples were obtained from vena mediana cubitii. After clotting for 60 min at room
      temperature, samples were centrifuged at 5000 rpm for 10-min. The serum samples were stored
      at -80°C until analysis.

      Serum COMP concentrations were analyzed with a commercially available enzyme-linked
      immunosorbent assay based on two monoclonal antibodies: COMP ELISA and AnaMar Medical
      (Sweden). ELISA analysis was performed in a private institution and assay procedures were
      followed according to the manufacturer's guidelines. The order of blood samples was mixed and
      biochemist was blind to allocation of samples. All blood samples were analyzed simultaneously
      to maintain uniform specificity across individuals.

      Statistical Procedures

      The effects of 12 weeks interventions on general fitness and serum COMP concentrations at
      pre-tests and post-tests were analyzed using 4x2 (groups and time) mixed repeated measures
      ANOVA for each variable. Paired-samples t-tests were employed for comparison of the serum
      COMP concentrations during rest, fatigue and recovery states. In order to decrease the
      probability of committing type-1 error, a method of multiple comparisons by Bonferroni
      confidence interval adjustment was performed.

      Sample size calculation was performed to eliminate type II error. Sample size was calculated
      using the G*Power 3.1.3 (Heinrich-Heine-University) software [5]. Significance level was set
      at 0.05 and a medium effect size (0.25) with two-sided calculation was used. Effect size
      contains the magnitude of difference between groups and values of 0.25, indicates medium
      effect of treatment [6]. By these assumptions, to achieve a power of 0.80, a sample size of
      36 participants was necessary. Conservatively, 48 subjects were recruited since we expected a
      20% dropout rate due to the demanding nature of the intervention program and our previous
      experience.
    

Intervention name(s): Running exercise; Cycling exercise; Swimming Exercise
Intervention type(s): Other; Other; Other
Intervention description(s): During this type of exercise intervention, subjects performed weight-bearing exercise. This group participated in sessions of 40-min per day, three days per week, for a period of 12 weeks; During this type of exercise intervention, subjects performed a partial weight-bearing exercise. This group participated in sessions of 40-min per day, three days per week, for a period of 12 weeks; During this type of exercise intervention, subjects performed a non-weight bearing exercise. This group participated in sessions of 40-min per day, three days per week, for a period of 12 weeks
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Screening
Keywords: Biochemical Marker; Fitness Exercises; Impact; Articular Cartilage