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Effect of training and sudden detraining on the patellar tendon and its enthesis in rats.

Frizziero A, Fini M, Salamanna F, Veicsteinas A, Maffulli N, Marini M - BMC Musculoskelet Disord (2011)

Bottom Line: In the detrained group, fiber organization and PG content were worse than that of the untrained groups and the untrained group showed a significantly higher score than the detrained group (p < 0.05).In the trained group, the PT was significantly thicker than in untrained group (p < 0.05).No significant differences in the enthesis area and subchondral bone volume among the three groups were seen.

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Affiliation: Department of Histology, Embryology and Applied Biology, University of Bologna, Italy.

ABSTRACT

Background: Different conditions may alter tendon characteristics. Clinical evidence suggests that tendon injuries are more frequent in athletes that change type, intensity and duration of training. Aim of the study was the assessment of training and especially detraining on the patellar tendon (PT) and its enthesis.

Methods: 27 male adult Sprague-Dawley rats were divided into 3 groups: 20 rats were trained on a treadmill for 10 weeks. Of these, 10 rats were euthanized immediately after training (trained group), and 10 were caged without exercise for 4 weeks before being euthanized (de-trained group). The remaining 7 rats were used as controls (untrained rats). PT insertion, structure (collagen fiber organization and proteoglycan, PG, content), PT thickness, enthesis area, and subchondral bone volume at the enthesis were measured by histomorphometry and microtomography.

Results: Both PG content and collagen fiber organization were significantly lower in untrained and detrained animals than in trained ones (p < 0.05 and p < 0.0001). In the detrained group, fiber organization and PG content were worse than that of the untrained groups and the untrained group showed a significantly higher score than the detrained group (p < 0.05). In the trained group, the PT was significantly thicker than in untrained group (p < 0.05). No significant differences in the enthesis area and subchondral bone volume among the three groups were seen.

Conclusions: Moderate exercise exerts a protective effect on the PT structure while sudden discontinuation of physical activity has a negative effect on tendons. The present results suggest that after a period of sudden de-training (such as after an injury) physical activity should be restarted with caution and with appropriate rehabilitation programs.

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Fibril birefringence observed with polarized microscopy in patellar tendon from the trained group. CF: collagen fibers. Magnification 10×.
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Figure 3: Fibril birefringence observed with polarized microscopy in patellar tendon from the trained group. CF: collagen fibers. Magnification 10×.

Mentions: Polarized microscopy, showed that even the smallest visible collagen fibril was birifrangent, which indicates the presence of elongated submicroscopic units oriented in the direction of the fiber axis. Such characteristic is particularly conspicuous in the trained tendon (Figure 3).


Effect of training and sudden detraining on the patellar tendon and its enthesis in rats.

Frizziero A, Fini M, Salamanna F, Veicsteinas A, Maffulli N, Marini M - BMC Musculoskelet Disord (2011)

Fibril birefringence observed with polarized microscopy in patellar tendon from the trained group. CF: collagen fibers. Magnification 10×.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3038990&req=5

Figure 3: Fibril birefringence observed with polarized microscopy in patellar tendon from the trained group. CF: collagen fibers. Magnification 10×.
Mentions: Polarized microscopy, showed that even the smallest visible collagen fibril was birifrangent, which indicates the presence of elongated submicroscopic units oriented in the direction of the fiber axis. Such characteristic is particularly conspicuous in the trained tendon (Figure 3).

Bottom Line: In the detrained group, fiber organization and PG content were worse than that of the untrained groups and the untrained group showed a significantly higher score than the detrained group (p < 0.05).In the trained group, the PT was significantly thicker than in untrained group (p < 0.05).No significant differences in the enthesis area and subchondral bone volume among the three groups were seen.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Histology, Embryology and Applied Biology, University of Bologna, Italy.

ABSTRACT

Background: Different conditions may alter tendon characteristics. Clinical evidence suggests that tendon injuries are more frequent in athletes that change type, intensity and duration of training. Aim of the study was the assessment of training and especially detraining on the patellar tendon (PT) and its enthesis.

Methods: 27 male adult Sprague-Dawley rats were divided into 3 groups: 20 rats were trained on a treadmill for 10 weeks. Of these, 10 rats were euthanized immediately after training (trained group), and 10 were caged without exercise for 4 weeks before being euthanized (de-trained group). The remaining 7 rats were used as controls (untrained rats). PT insertion, structure (collagen fiber organization and proteoglycan, PG, content), PT thickness, enthesis area, and subchondral bone volume at the enthesis were measured by histomorphometry and microtomography.

Results: Both PG content and collagen fiber organization were significantly lower in untrained and detrained animals than in trained ones (p < 0.05 and p < 0.0001). In the detrained group, fiber organization and PG content were worse than that of the untrained groups and the untrained group showed a significantly higher score than the detrained group (p < 0.05). In the trained group, the PT was significantly thicker than in untrained group (p < 0.05). No significant differences in the enthesis area and subchondral bone volume among the three groups were seen.

Conclusions: Moderate exercise exerts a protective effect on the PT structure while sudden discontinuation of physical activity has a negative effect on tendons. The present results suggest that after a period of sudden de-training (such as after an injury) physical activity should be restarted with caution and with appropriate rehabilitation programs.

Show MeSH
Related in: MedlinePlus