The goal of this clinical trial is to examine the regional protein turnover in tendon tissue from patients with chronic patellar tendinopathy and comparing this to healthy controls. Further we will examine the effect of resistance training on protein turnover in healthy individuals.

Inclusion Criteria:

• Physical active men and women
• Body mass index 18,5 - 30 kg/m2

Inclusion Criteria for the chronic tendinopathy group:

• Debut of symptom > 90 days prior to inclusion.
• Subjective activity related pain in patella tendon.
• Clinical symptoms of patella tendinopathy.
• Ultrasound verification of at least 1 in three of the following: Enchanced anterior-posterior diameter, increased Doppler signal and/or a hypoechoic area in the diseased part of the tendon.

Exclusion Criteria for all participants:

• Former knee surgery or injuries to the patella tendon.
• Local injection of corticosteroids within 12 months.
• Medication that affects protein synthesis in tendon tissue.
• Former/current use of anabolic steroids or growth hormone.
• Smoking
• Known rheumatoid disease or diabetes.
• Former participation in trials using deuterated water and 15N tracers.
• Treatment for patella tendinopathy within 3 months.

Data will be shared with other researchers upon request.