An exploratory study to investigate the association between age, physical activity, femoral trochlear cartilage thickness and biomarkers of tissue metabolism in adult males.

PURPOSE: To investigate the association between age, physical activity, femoral trochlear cartilage thickness and biomarkers of tissue metabolism in a cross-sectional sample of adult males. This study utilizes several emerging biomarkers that have been associated with early joint degenerative changes; serum COMP (cartilage oligomeric matrix protein), HA (hyaluronan) and lubricin. METHODS: Eighty-one males (age: mean (range): 43(18-70) years; body mass index: 25.2 (21.0-30.6) kg/m2) volunteered. Resting serum COMP, HA and lubricin concentrations were determined via commercially available enzyme-linked immunosorbent assay (ELISA) and femoral trochlear cartilage thickness via supra-patellar ultrasound imaging. Physical activity levels were assessed using questionnaires. Statistical analyses were performed using correlation and regression analyses. RESULTS: Age was correlated with lateral trochlear cartilage thickness (r = - 0.372; p < 0.01) and serum COMP (r = 0.342; p < 0.01). 7-day physical activity was correlated with serum COMP (r = 0.357, p < 0.01), and 12-month physical activity with both lateral trochlear cartilage thickness (r = 0.340, p = 0.01) and serum HA (r = 0.296, p < 0.05). Regression analyses revealed that age significantly accounted for the variability in lateral cartilage thickness and serum COMP, following the adjustment for potential cofounders. However, the association between age and lateral trochlear cartilage thickness was not moderated by physical activity levels (all p > 0.05). CONCLUSION: This study indicates that older age may be associated with thinner lateral trochlear cartilage and higher cartilage turnover. Being physically active may also be positive for lateral trochlear cartilage thickness. However, overall, both age and physical activity level only account for a small amount of the variability in cartilage thickness and serum biomarkers.

The time course and mechanisms of change in biomarkers of joint metabolism in response to acute exercise and chronic training in physiologic and pathological conditions.

PURPOSE: The benefits of exercise across the lifespan and for a wide spectrum of health and diseases are well known. However, there remains less clarity as to the effects of both acute and chronic exercise on joint health. Serum biomarkers of joint metabolism are sensitive to change and have the potential to differentiate between normal and adverse adaptations to acute and chronic load. Therefore, the primary objective of this review is to evaluate how serum biomarkers can inform our understanding of how exercise affects joint metabolism. METHODS: A comprehensive literature search was completed to identify joint biomarkers previously used to investigate acute and chronic exercise training. RESULTS: Identified biomarkers included those related to joint cartilage, bone, synovium, synovial fluid, and inflammation. However, current research has largely focused on the response of serum cartilage oligomeric matrix protein (COMP) to acute loading in healthy young individuals. Studies demonstrate how acute loading transiently increases serum COMP (i.e., cartilage metabolism), which is mostly dependent on the duration of exercise. This response does not appear to be associated with any lasting deleterious changes, cartilage degradation, or osteoarthritis. CONCLUSION: Several promising biomarkers for assessing joint metabolism exist and may in future enhance our understanding of the physiological response to acute and chronic exercise. Defining 'normal' and 'abnormal' biomarker responses to exercise and methodological standardisation would greatly improve the potential of research in this area to understand mechanisms and inform practice.

The Reliability of Suprapatellar Transverse Sonographic Assessment of Femoral Trochlear Cartilage Thickness in Healthy Adults.

OBJECTIVES: To determine the intrasession reliability of femoral cartilage thickness measurements using sonography and extend the pool of normative data for cartilage thickness measurements assessed by sonography. METHODS: A total of 77 healthy participants (55 men, 22 women), with an average age of 43 ± 18 (mean ± standard deviation) years, volunteered. Resting suprapatellar sonography was used to image trochlear cartilage thickness on 2 separate occasions a maximum of 7 days apart. Reliability was evaluated with intraclass correlation coefficients, Bland-Altman analysis, standard error of measurement, and the smallest real difference. Normative data was assessed using linear, multiple regression models and independent group t tests. RESULTS: The test-retest level of agreement at all locations was high (intraclass correlation coefficient, 0.779-0.843), which increased to high-very high in young adults (intraclass correlation coefficient, 0.884-0.920). The standard error of measurement was 8.2% to 8.3% at all locations and reduced further to 5.4% to 6.3% in younger adults. The smallest real difference was between 22.8% and 23.1% for the full sample and 14.9% and 17.5% in young adults only. Multiple regression analyses demonstrated that age, weight, female sex, and a high physical activity frequency could significantly predict cartilage thickness at all locations (P < .05); however, female sex was the only significant independent predictor in all models (all P < .01). Females also had thinner cartilage at all locations (P < .01). CONCLUSION: Suprapatellar sonography demonstrates high intratester reliability and measurement precision and is a promising method to assess trochlear cartilage thickness. Being female may impact femoral cartilage thickness more than other potential risk factors for knee osteoarthritis such as age, weight, and high physical activity frequency.

The effect of aerobic walking and lower body resistance exercise on serum COMP and hyaluronan, in both males and females.

PURPOSE: To compare the serum cartilage oligomeric matrix protein (COMP) and hyaluronan (HA) response to walking (high-repetition loading) and resistance training exercise (low-repetition loading) in males and females. METHODS: 15 males (age: 28 ± 6 years; BMI: 24 ± 2; mean ± SD) and 15 females (age: 26 ± 4 years; BMI: 23 ± 2) completed both a 40-min walk at 80% of maximum heart rate and a 40-min lower body resistance training protocol, separated by a minimum of 48 h. Serum COMP and HA were determined at rest, immediately post, and 30-min post exercise. Resting femoral cartilage thickness was also measured using ultrasonography. RESULTS: COMP increased following walking (28.9%; P < 0.001) and resistance training exercise (26.0%; P < 0.001), remaining above baseline post-exercise following walking (mean difference: +28.3 ng/ml; 95% CI 3.8-52.8 ng/ml; P = 0.02). Although the exercise response did not differ for gender, COMP concentrations were higher in males than in females at all time points (all, P < 0.001). In contrast, HA concentrations did not change following either modality of exercise. However, females demonstrated higher HA pre-exercise (37.7 ± 17.8 vs 26.2 ± 12.8 ng/ml; P = 0.006) and immediately post exercise (38.0 ± 19.0 vs 28.2 ± 15.5 ng/ml; P = 0.033) compared to men. Finally, following adjustment for body size, femoral cartilage thickness was greater in men compared to women (notch: 2.66 vs 1.74 mm, P < 0.001). CONCLUSION: The effect of a single bout of lower body exercise on serum COMP and HA is independent of exercise modality in healthy men and women. Furthermore, having thicker femoral cartilage and higher baseline COMP in males does not appear to influence how the cartilage responds to exercise.

The effect of vigorous running and cycling on serum COMP, lubricin, and femoral cartilage thickness: a pilot study.

PURPOSE: Our aim was to investigate lubricin, cartilage oligomeric matrix protein (COMP), and femoral cartilage deformation in response to different biomechanical loading of the knee joint (running vs cycling). METHODS: Serum lubricin and COMP concentrations (enzyme-linked immunosorbent assay), and femoral cartilage thickness (suprapatellar transverse ultrasonography) were determined in 11 male runners (age: 40 ± 6 years; weight: 76 ± 8 kg) and 11 male cyclists (35 ± 12 years; 75 ± 5 kg) at baseline, immediately after, and 30 min after vigorous exercise (time trial: 10-km run or 25-km cycle). RESULTS: At baseline, lubricin (runners: 104.0 ± 19.8 ng/ml; cyclists: 119.1 ± 23.9 ng/ml) and COMP (runners: 804.1 ± 87.5 ng/ml; cyclists: 693.0 ± 84.7 ng/ml) did not significantly differ; however, vigorous exercise was accompanied by an increase in lubricin (cyclists: 39.4 %; p < 0.05; runners: 56.9 %; p < 0.05) and COMP (cyclists: 32.1 %; p < 0.05; runners: 14.2 %; p = 0.14) that returned toward baseline following 30 min of rest (p < 0.05). No between-group differences were observed for baseline cartilage thickness at the intercondyle notch, medial condyle, and lateral condyle, and vigorous exercise did not result in significant change for either group. CONCLUSIONS: In the absence of ultrasonographic knee cartilage deformation, the response of serum lubricin and COMP following acute vigorous exercise indicates an increase in joint lubrication and cartilage metabolism, respectively, which appears largely independent of exercise modality.