Fibril morphology and tendon mechanical properties in patellar tendinopathy: effects of heavy slow resistance training

Mads Kongsgaard; Klaus Qvortrup; Jytte Overgaard Larsen; Per Aagaard; Simon Doessing; Philip Hansen; Michael Kjaer; S Peter Magnusson; Mads Kongsgaard; Klaus Qvortrup; Jytte Grambo Larsen; Per Aagaard; Simon Doessing; Philip Hansen; Michael Kjaer; S Peter Magnusson

doi:10.1177/0363546509350915

Fibril morphology and tendon mechanical properties in patellar tendinopathy: effects of heavy slow resistance training

Mads Kongsgaard, Klaus Qvortrup, Jytte Overgaard Larsen, Per Aagaard, Simon Doessing, Philip Hansen, Michael Kjaer, S Peter Magnusson, Mads Kongsgaard, Klaus Qvortrup, Jytte Grambo Larsen, Per Aagaard, Simon Doessing, Philip Hansen, Michael Kjaer, S Peter Magnusson

125 Citations (Scopus)

Abstract

BACKGROUND: Patellar tendinopathy is characterized by pathologic abnormalities. Heavy slow resistance training (HSR) is effective in the management of patellar tendinopathy, but the underlying functional mechanisms remain elusive. PURPOSE: To investigate fibril morphology and mechanical properties in patellar tendinopathy and the effect of HSR on these properties. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Eight male patients with patellar tendinopathy completed 12 weeks of HSR. Nine healthy subjects served as controls. Assessments were conducted at baseline and at 12 weeks. Patients assessed symptoms/function and maximal tendon pain during activity. Tendon biopsy samples were analyzed for fibril density, volume fraction, and mean fibril area. Tendon mechanical properties were assessed using force and ultrasonography samplings. RESULTS: Patients improved in symptoms/function (P = .02) and maximal tendon pain during activity (P = .008). Stiffness and modulus of control and tendinopathy tendons were similar at baseline. Stiffness remained unaffected in control tendons (3487 +/- 392 to 3157 +/- 327 N/mm, P = .57) but declined in tendinopathic tendons at 12 weeks (3185 +/- 187 to 2701 +/- 201 N/mm, P = .04). At baseline, fibril volume fraction was equal, fibril density smaller (P = .03), and mean fibril area tended to be higher in tendinopathy versus controls (P = .07). Fibril morphology remained unchanged in controls but fibril density increased (70% +/- 18%, P = .02) and fibril mean area decreased (-26% +/- 21%, P = .04) in tendinopathic tendons after HSR. CONCLUSION: Fibril morphology is abnormal in tendinopathy, but tendon mechanical properties are not. Clinical improvements after HSR were associated with changes in fibril morphology toward normal fibril density and mean fibril area. Heavy slow resistance training improved the clinical outcome of patellar tendinopathy, and these improvements were associated with normalization of fibril morphology, most likely due to a production of new fibrils.

Original language	English
Journal	American Journal of Sports Medicine
Volume	38
Issue number	4
Pages (from-to)	749-56
Number of pages	8
ISSN	0363-5465
DOIs	https://doi.org/10.1177/0363546509350915 https://doi.org/10.1177/0363546509350915
Publication status	Published - 1 Apr 2010

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Kongsgaard, M., Qvortrup, K., Larsen, J. O., Aagaard, P., Doessing, S., Hansen, P., Kjaer, M., Magnusson, S. P., Kongsgaard, M., Qvortrup, K., Grambo Larsen, J., Aagaard, P., Doessing, S., Hansen, P., Kjaer, M., & Magnusson, S. P. (2010). Fibril morphology and tendon mechanical properties in patellar tendinopathy: effects of heavy slow resistance training. American Journal of Sports Medicine, 38(4), 749-56. https://doi.org/10.1177/0363546509350915, https://doi.org/10.1177/0363546509350915

Kongsgaard, M, Qvortrup, K, Larsen, JO, Aagaard, P, Doessing, S, Hansen, P, Kjaer, M , Magnusson, SP, Kongsgaard, M, Qvortrup, K, Grambo Larsen, J, Aagaard, P, Doessing, S, Hansen, P, Kjaer, M & Magnusson, SP 2010, 'Fibril morphology and tendon mechanical properties in patellar tendinopathy: effects of heavy slow resistance training', American Journal of Sports Medicine, vol. 38, no. 4, pp. 749-56. https://doi.org/10.1177/0363546509350915, https://doi.org/10.1177/0363546509350915

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title = "Fibril morphology and tendon mechanical properties in patellar tendinopathy: effects of heavy slow resistance training",

abstract = "BACKGROUND: Patellar tendinopathy is characterized by pathologic abnormalities. Heavy slow resistance training (HSR) is effective in the management of patellar tendinopathy, but the underlying functional mechanisms remain elusive. PURPOSE: To investigate fibril morphology and mechanical properties in patellar tendinopathy and the effect of HSR on these properties. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Eight male patients with patellar tendinopathy completed 12 weeks of HSR. Nine healthy subjects served as controls. Assessments were conducted at baseline and at 12 weeks. Patients assessed symptoms/function and maximal tendon pain during activity. Tendon biopsy samples were analyzed for fibril density, volume fraction, and mean fibril area. Tendon mechanical properties were assessed using force and ultrasonography samplings. RESULTS: Patients improved in symptoms/function (P = .02) and maximal tendon pain during activity (P = .008). Stiffness and modulus of control and tendinopathy tendons were similar at baseline. Stiffness remained unaffected in control tendons (3487 +/- 392 to 3157 +/- 327 N/mm, P = .57) but declined in tendinopathic tendons at 12 weeks (3185 +/- 187 to 2701 +/- 201 N/mm, P = .04). At baseline, fibril volume fraction was equal, fibril density smaller (P = .03), and mean fibril area tended to be higher in tendinopathy versus controls (P = .07). Fibril morphology remained unchanged in controls but fibril density increased (70% +/- 18%, P = .02) and fibril mean area decreased (-26% +/- 21%, P = .04) in tendinopathic tendons after HSR. CONCLUSION: Fibril morphology is abnormal in tendinopathy, but tendon mechanical properties are not. Clinical improvements after HSR were associated with changes in fibril morphology toward normal fibril density and mean fibril area. Heavy slow resistance training improved the clinical outcome of patellar tendinopathy, and these improvements were associated with normalization of fibril morphology, most likely due to a production of new fibrils.",

author = "Mads Kongsgaard and Klaus Qvortrup and Larsen, {Jytte Overgaard} and Per Aagaard and Simon Doessing and Philip Hansen and Michael Kjaer and Magnusson, {S Peter} and Mads Kongsgaard and Klaus Qvortrup and {Grambo Larsen}, Jytte and Per Aagaard and Simon Doessing and Philip Hansen and Michael Kjaer and Magnusson, {S Peter}",

year = "2010",

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doi = "10.1177/0363546509350915",

language = "English",

volume = "38",

pages = "749--56",

journal = "American Journal of Sports Medicine",

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TY - JOUR

T1 - Fibril morphology and tendon mechanical properties in patellar tendinopathy: effects of heavy slow resistance training

AU - Kongsgaard, Mads

AU - Qvortrup, Klaus

AU - Larsen, Jytte Overgaard

AU - Aagaard, Per

AU - Doessing, Simon

AU - Hansen, Philip

AU - Kjaer, Michael

AU - Magnusson, S Peter

AU - Kongsgaard, Mads

AU - Qvortrup, Klaus

AU - Grambo Larsen, Jytte

AU - Aagaard, Per

AU - Doessing, Simon

AU - Hansen, Philip

AU - Kjaer, Michael

AU - Magnusson, S Peter

PY - 2010/4/1

Y1 - 2010/4/1

N2 - BACKGROUND: Patellar tendinopathy is characterized by pathologic abnormalities. Heavy slow resistance training (HSR) is effective in the management of patellar tendinopathy, but the underlying functional mechanisms remain elusive. PURPOSE: To investigate fibril morphology and mechanical properties in patellar tendinopathy and the effect of HSR on these properties. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Eight male patients with patellar tendinopathy completed 12 weeks of HSR. Nine healthy subjects served as controls. Assessments were conducted at baseline and at 12 weeks. Patients assessed symptoms/function and maximal tendon pain during activity. Tendon biopsy samples were analyzed for fibril density, volume fraction, and mean fibril area. Tendon mechanical properties were assessed using force and ultrasonography samplings. RESULTS: Patients improved in symptoms/function (P = .02) and maximal tendon pain during activity (P = .008). Stiffness and modulus of control and tendinopathy tendons were similar at baseline. Stiffness remained unaffected in control tendons (3487 +/- 392 to 3157 +/- 327 N/mm, P = .57) but declined in tendinopathic tendons at 12 weeks (3185 +/- 187 to 2701 +/- 201 N/mm, P = .04). At baseline, fibril volume fraction was equal, fibril density smaller (P = .03), and mean fibril area tended to be higher in tendinopathy versus controls (P = .07). Fibril morphology remained unchanged in controls but fibril density increased (70% +/- 18%, P = .02) and fibril mean area decreased (-26% +/- 21%, P = .04) in tendinopathic tendons after HSR. CONCLUSION: Fibril morphology is abnormal in tendinopathy, but tendon mechanical properties are not. Clinical improvements after HSR were associated with changes in fibril morphology toward normal fibril density and mean fibril area. Heavy slow resistance training improved the clinical outcome of patellar tendinopathy, and these improvements were associated with normalization of fibril morphology, most likely due to a production of new fibrils.

AB - BACKGROUND: Patellar tendinopathy is characterized by pathologic abnormalities. Heavy slow resistance training (HSR) is effective in the management of patellar tendinopathy, but the underlying functional mechanisms remain elusive. PURPOSE: To investigate fibril morphology and mechanical properties in patellar tendinopathy and the effect of HSR on these properties. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Eight male patients with patellar tendinopathy completed 12 weeks of HSR. Nine healthy subjects served as controls. Assessments were conducted at baseline and at 12 weeks. Patients assessed symptoms/function and maximal tendon pain during activity. Tendon biopsy samples were analyzed for fibril density, volume fraction, and mean fibril area. Tendon mechanical properties were assessed using force and ultrasonography samplings. RESULTS: Patients improved in symptoms/function (P = .02) and maximal tendon pain during activity (P = .008). Stiffness and modulus of control and tendinopathy tendons were similar at baseline. Stiffness remained unaffected in control tendons (3487 +/- 392 to 3157 +/- 327 N/mm, P = .57) but declined in tendinopathic tendons at 12 weeks (3185 +/- 187 to 2701 +/- 201 N/mm, P = .04). At baseline, fibril volume fraction was equal, fibril density smaller (P = .03), and mean fibril area tended to be higher in tendinopathy versus controls (P = .07). Fibril morphology remained unchanged in controls but fibril density increased (70% +/- 18%, P = .02) and fibril mean area decreased (-26% +/- 21%, P = .04) in tendinopathic tendons after HSR. CONCLUSION: Fibril morphology is abnormal in tendinopathy, but tendon mechanical properties are not. Clinical improvements after HSR were associated with changes in fibril morphology toward normal fibril density and mean fibril area. Heavy slow resistance training improved the clinical outcome of patellar tendinopathy, and these improvements were associated with normalization of fibril morphology, most likely due to a production of new fibrils.

U2 - 10.1177/0363546509350915

DO - 10.1177/0363546509350915

M3 - Journal article

C2 - 20154324

SN - 0363-5465

VL - 38

SP - 749

EP - 756

JO - American Journal of Sports Medicine

JF - American Journal of Sports Medicine

IS - 4

ER -

Fibril morphology and tendon mechanical properties in patellar tendinopathy: effects of heavy slow resistance training

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