Early development of tendinopathy in humans: Sequence of pathological changes in structure and tissue turnover signaling.

Overloading of tendon tissue with resulting chronic pain (tendinopathy) is a common disorder in occupational-, leisure- and sports-activity, but its pathogenesis remains poorly understood. To investigate the very early phase of tendinopathy, Achilles and patellar tendons were investigated in 200 physically active patients and 50 healthy control persons. Patients were divided into three groups: symptoms for 0-1 months (T1), 1-2 months (T2) or 2-3 months (T3). Tendinopathic Achilles tendon cross-sectional area determined by ultrasonography (US) was ~25% larger than in healthy control persons. Both Achilles and patellar anterior-posterior diameter were elevated in tendinopathy, and only later in Achilles was the width increased. Increased tendon size was accompanied by an increase in hypervascularization (US Doppler flow) without any change in mRNA for angiogenic factors. From patellar biopsies taken bilaterally, mRNA for most growth factors and tendon components remained unchanged (except for TGF-beta1 and substance-P) in early tendinopathy. Tendon stiffness remained unaltered over the first three months of tendinopathy and was similar to the asymptomatic contra-lateral tendon. In conclusion, this suggests that tendinopathy pathogenesis represents a disturbed tissue homeostasis with fluid accumulation. The disturbance is likely induced by repeated mechanical overloading rather than a partial rupture of the tendon.

Effects of Long-Term Physical Activity and Diet on Skin Glycation and Achilles Tendon Structure.

Advanced glycation end-products (AGEs) accumulate with aging and have been associated with tissue modifications and metabolic disease. Regular exercise has several health benefits, and the purpose of this study was to investigate the effect of regular long-term exercise and diet on skin autofluorescence (SAF) as a measure of glycation and on Achilles tendon structure. In connection with the 2017 European Masters Athletics Championships Stadia, high-level male athletes (n = 194) that had regularly trained for more than 10 years were recruited, in addition to untrained controls (n = 34). SAF was non-invasively determined using an AGE Reader. Achilles tendon thickness and vascular Doppler activity were measured by ultrasonography, and diet was assessed by a questionnaire. There was no significant difference in SAF between the athletes and controls. However, greater duration of exercise was independently associated with lower SAF. Diet also had an effect, with a more "Western" diet in youth being associated with increased SAF. Furthermore, our data demonstrated that greater Achilles tendon thickness was associated with aging and training. Together, our data indicate that long-term exercise may yield a modest reduction in glycation and substantially increase Achilles tendon size, which may protect against injury.

Lack of muscle fibre hypertrophy, myonuclear addition, and satellite cell pool expansion with resistance training in 83-94-year-old men and women.

AIMS: To examine satellite cell and myonuclear content in very old (≥83 years) individuals, and the response to heavy resistance training. METHODS: A group of very old men and women (Old, 83-94 years, n = 29) was randomized to 12 weeks of heavy resistance training or untrained controls. A group of young men who did not resistance train (Young, 19-27 years, n = 9) were included for comparison. RESULTS: Compared to young men, prior to training the old men had smaller type II fibres (-38%, P < 0.001), lower satellite cell content (-52%, P < 0.001), smaller myonuclear domain (-30%, P < 0.001), and a trend for lower myonuclear content (-13%, P = 0.09). Old women were significantly different from old men for these parameters, except for satellite cell content. Resistance training had no effect on these parameters in these old men and women. Fibre-size specific analysis showed strong correlations between fibre size and myonuclei per fibre and between fibre size and myonuclear domain for both fibre types (r = 0.94-0.99, P < 0.0001). In contrast, muscle fibre perimeter per myonucleus seemed to be constant across the range in fibre size, particularly in type I fibres (r = -0.31, P = 0.17). CONCLUSIONS: The present data demonstrate that type II fibre size, satellite cell content and myonuclear domain is significantly smaller in very old men compared to young men, while myonuclear content is less affected. These parameters were not improved with heavy resistance training at the most advanced stage of ageing.

Corticosteroid injection is the best treatment in plantar fasciitis if combined with controlled training.

PURPOSE: Plantar fasciitis is a very common (lifetime incidence ~ 10%) and long-lasting injury with major impact on daily function. Combining corticosteroid injection and physical training (strength training and stretching) was hypothesized to result in a superior effect compared to each treatment separately. METHODS: A single blinded randomized controlled superiority trial conducted in 2013-2014 with a 2-year follow-up (end Sept 2016). 123 consecutive patients (20-65 years) referred to two study centers in Denmark: Institute of Sports Medicine, Bispebjerg Hospital, University of Copenhagen and a private rheumatology clinic with symptoms of plantar fasciitis, and ultrasound measured thickness above 4.0 mm were invited. 25 did not fulfill the inclusion criteria (mainly ultrasound criteria) and 8 refused participation. 90 patients were randomized (pulling sealed envelopes) to 3 groups: (1) 3 months strength training and stretching (n = 30), (2) corticosteroid injections with monthly intervals until thickness < 4.0 mm (maximum 3 injections) (n = 31), (3) combination of the two treatments (n = 29). During the 3 months intervention period load reduction was recommended (cushioning shoes and insoles and abstaining from running and jumping). The main outcome was improvement in Pain at function on a 100-mm VAS score and in Foot Function Index (FFI, range 0-230) at 6 months (Clinicaltrials.gov Identifier: NCT01994759). RESULTS: All groups improved significantly over time, but the combination of corticosteroid injection and training (strength training and stretching) had a superior effect at all time points. The mean difference between the combined treatment and training was 40 points in FFI (95% confidence interval (CI) 63-17 points, p < 0.001) and 20 mm for VAS function pain (CI 35-5 mm, p < 0.01). The mean difference between the combined treatment and corticosteroid injections only was 29 points in FFI (CI 52-7 points, p < 0.01) and 17 mm for VAS function pain (CI 32-2 mm, p < 0.05). All differences were clinically relevant. CONCLUSION: The best treatment for plantar fasciitis is the combination of corticosteroid injections and training (strength training and stretching). This combined treatment is superior both in the short- and in the longterm. Corticosteroid injections combined with controlled training are recommended as first line treatment in patients with plantar fasciitis. LEVEL OF EVIDENCE: 1.