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Background: A patellar tendon injury is a common injury in sports. The optimal time to start training after an acute, proximal patellar enthesis injury is still unclear. Hypothesis: The time to start training after an acute, proximal patellar enthesis injury significantly affects healing of the patellar tendon 4 weeks after the injury. Study Design: Controlled laboratory study. Methods: The left hindlimbs of 35 mature female rabbits were randomly assigned to 5 injury groups including a 4-week natural healing group (NH4W) and 4 training groups that started low-intensity training at 24 hours (POST24), 48 hours (POST48), 72 hours (POST72), and 96 hours (POST96) after an acute patellar tendon injury, with 7 limbs in each group. The right hindlimbs of the NH4W group were used as a control group (CON). An acute, proximal patellar enthesis injury was created in all injury groups. The training groups underwent low-intensity quadriceps training for 2 hours per day and 3 days per week for 4 weeks. Histological and radiographic data were collected and analyzed. Results: The cell densities of the training groups were significantly lower than those of the NH4W and CON groups ( P = .01). The fibrocartilage zone was significantly thicker in the POST24, POST48, and POST72 groups compared with the CON and NH4W groups and was the thickest in the POST24 group ( P = .01). The bone surface to bone volume ratio was significantly higher in all the injury groups compared with the CON group and in the POST24 group compared with the other groups ( P = .01). Trabecular thickness was significantly lower in all the injury groups compared with the CON group and in the POST24 group compared with the other groups ( P = .01). Conclusion: Resting without training in the first 96 hours after an acute patellar tendon enthesis injury resulted in the best recovery of cell density in the tendon enthesis 4 weeks after the injury. Starting training 96 hours after the injury resulted in the best recovery of fibrocartilage zone thickness. Starting training 48 to 96 hours after the injury resulted in the best healing of the bone component of the attachment site 4 weeks after the injury. The optimal time to start training may be longer than 96 hours after an acute patellar tendon enthesis injury for the best overall healing of the tendon enthesis 4 weeks after the injury. Clinical Relevance: A rest of a minimal 72 hours may be needed for the best healing of a patellar tendon enthesis after an acute injury. Future studies are needed to determine the optimal time to start training after an acute patellar tendon injury.

Bone-tendon junction (BTJ) overuse injuries are common athletic and occupational problems. BTJ injuries may sometimes be caused by resuming training too early after injury. To study the effects of post-injury resuming training within 48 hours on the acute injury healing process, as it is often the case for athletes. Twelve mature female rabbits were assigned to one of the following groups: acute injury (AI, n = 6), post-injury early return to training (PIERT, n = 6) and normal control (CON, n = 6). Tissue specimens were harvested at week 4. The radiological and histological characteristics of the AI and PIERT groups were compared among the groups. The trabecular thickness of the PIERT group was significantly different from those of the AI and CON group. A histological evaluation revealed poor collagen fibre alignment, extensive scar tissue and lowered cell density in the AI and PIERT groups compared with the CON group, but no significant differences were observed between the AI group and the PIERT group. The fibrocartilage zone and proteoglycan area in the PIERT group were significantly different from those in AI group. No differences were observed in the Total VOI volume (TV), Object volume (OBV), Percent object volume (BV/TV) and trabecular number (Tb.N) among the AI, PIERT and CON groups. In conclusion, a repeatable animal model of bone-tendon junction acute micro-damage by puncture was established. Resuming training in 48 hours did not significantly deteriorate the BTJ injury healing, but improved bone remodelling and increased fibrocartilage zone thickness. Key pointsAn easy and repeatable bone-tendon junction injury model was established in this study, it will provide a platform to the injury research.Post-injury resuming training in 48 hours did not delay the acute bone-tendon junction injury healing process, it provided a basic theory for the post-injury training.To find the proper post-injury training intensity will help athletes to train scientifically, it is the destination of our next research.

Purpose To determine the association of different levels of cardiorespiratory fitness (CRF), an objective indicator of habitual physical activity, with gallbladder disease. Methods In the Aerobics Center Longitudinal Study (ACLS) database, 41,528 men and 13,206 women aged 20–90 years, with body mass index of 18.5 or more and without history of cardiovascular disease and cancer, received a preventive examination at the Cooper Clinic in Dallas, Texas, between 1970 and 2003. CRF was quantified as maximal metabolic equivalents and classified as low, moderate, and high based on traditional ACLS cut points. Gallbladder disease was defined as physician-diagnosed gallbladder disease. Results When compared with low CRF, adjusted odds ratios and 95% confidence intervals for gallbladder disease for those with moderate and high CRF were 0.74 (0.55–0.99) and 0.59 (0.42–0.82), respectively when adjusted for all the potential confounders. Each one metabolic equivalent increment of CRF was associated with 10% lower odds of gallbladder disease in all participants (P for trend