Osteoarthritis (OA) is a multifactorial, progressive, and painful disease. OA is influenced by genetic and environmental factors, including mechanical stress . To overcome difficulties in studying osteoarthritis in humans, a variety of animal models have been developed [2–4]. The use of strenuous running helps simulate long-term stress on weight-bearing joints. This model does not require surgical procedures; therefore it can detect subtle symptoms of osteoarthritis without surgical modification. Running protocols for rats usually require 30 km in 6 weeks (Table 1), but a proportion of rats often drop off the protocol because of foot problems, and quantitative data for this dropout rate have not been reported [5, 6]. We previously used 30 km of running protocol and experienced drop out problems. Here, we first examined the dropout rate of rats during a forced 30-km running protocol.Table 1Reports on the effects of running exercise on articular cartilage in Wistar ratsStudyRunning distanceRunning periodOA inducedMethodEffectSekiya et al.  200930 km6 weeksNoHarmfulSiebelt et al.  201131.8 km6 weeksNoHarmfulBeckett et al.  201230 km / 55 km3 / 6 weeksNoHarmfulPap et al.  199830 km12 weeksYesIntracranial self stimulationHarmfulSiebelt et al.  201415 km6 weeksYesPapain injectionHarmfulSaito et al. 201515 km3 weeksYesMIA 0.1 mg injectionHarmfulGalois et al.  200415 km4 weeksYesACLTBeneficialCifuentes et al.  201015 km8 weeksYesMIA 1.2 mg injectionBeneficial Abbreviations: ACLT anterior cruciate ligament transection, MIA mono-iodoacetate