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Background: Although Achilles tendon overuse injuries occur commonly, our understanding of the pathologic changes and the factors that predispose athletes to them is limited.
Purpose: To identify measurable intrinsic risk factors for Achilles tendon overuse injuries.
Study Design: Prospective cohort study.
Methods: Sixty-nine male officer cadets followed the same 6-week basic military training. Before this training, each subject was evaluated for anthropometrical characteristics, isokinetic ankle muscle strength, ankle joint range of motion, Achilles tendon stiffness, explosive strength, and leisure and sports activity. During military training, Achilles tendon overuse injuries were registered and diagnosed by the same medical doctor. To identify the intrinsic risk factors, a multivariate analysis with the use of stepwise logistic regression was performed. The sensitivity, specificity, and cutoff values of the risk factors were evaluated by receiver operating characteristic curve analysis.
Results: Ten of the 69 male recruits (14.5%) sustained an Achilles tendon overuse injury diagnosed on the basis of medical history and clinical examination. Analysis revealed that male recruits with lower plantar flexor strength and increased dorsiflexion excursion were at a greater risk of Achilles tendon overuse injury. The cutoff value of the plantar flexor strength at 85% sensitivity was 50.0 N·m, with a 4.5% specificity; the cutoff value of the dorsiflexion range of motion at 85% sensitivity was 9.0°, with 24.2% specificity.
Conclusions: The strength of the plantar flexors and amount of dorsiflexion excursion were identified as significant predictors of an Achilles tendon overuse injury. A plantar flexor strength lower than 50.0 N·m and dorsiflexion range of motion higher than 9.0° were possible thresholds for developing an Achilles tendon overuse injury.
Re: Risk factors for achilles tendon overuse injury
Lower limb kinematics of subjects with chronic achilles tendon injury during running.
Donoghue OA, Harrison AJ, Laxton P, Jones RK. Res Sports Med. 2008;16(1):23-38
This study examined the kinematic differences between subjects who had a history of chronic Achilles tendon (AT) injury and matched controls during running. Eleven subjects from each group ran barefoot (BF) and shod at self-selected speeds on a treadmill. Three-dimensional angles describing rearfoot and lower limb motion were calculated throughout stance. Five footfalls were obtained for each subject and condition. Pairwise comparisons revealed greater eversion, ankle dorsiflexion and less leg abduction during stance in the AT group compared with controls. Running kinematics were exaggerated in shod compared with BF conditions, as expected from previous research. The differences between conditions were more exaggerated in AT subjects compared with control subjects. Further analysis using a curve-based approach is recommended.
OBJECTIVE: The aim of this study was to investigate the kinetics, kinematics and muscle activity in runners with Achilles tendinopathy. DESIGN: Case-control study. SETTING: Biomechanics laboratory.
PARTICIPANTS: Twenty one runners free from injury and twenty one runners with Achilles tendinopathy performed 10 running trials with standardized running shoes. Injured runners were diagnosed clinically according to established diagnostic criteria. Uninjured runners were injury free for at least 2 years. Main outcome measurements: During each trial, kinetic and lower limb kinematic data were measured using a strain gauge force plate and six infrared cameras respectively. EMG data from six muscles (tibialis anterior (TA), peroneus longus (PE), lateral gastrocnemius (LG), rectus femoris (RF), biceps femoris (BF) and gluteus medius (GM)) were measured with a telemetric EMG system.
RESULTS: Knee range of motion (heel strike to midstance) was significantly lower in injured runners compared with the uninjured runners. Similarly, pre activation (IEMG in 100 ms before heel strike) of TA was lower for injured runners than uninjured runners. RF and GM IEMG activity 100 ms after heel strike was also lower in the injured group. However, impact forces were not different between the two groups.
CONCLUSION: Altered knee kinematics and reduced muscle activity are associated with Achilles Tendinopathy in runners. Rehabilitation exercises or other mechanisms (e.g. footwear) that affect kinematics and muscle activity may therefore be beneficial in the treatment of runners with Achilles tendinopathy.
The purpose of this prospective cohort study was to identify dynamic gait-related risk factors for Achilles tendinopathy (AT) in a population of novice runners. Prior to a 10-week running program, force distribution patterns underneath the feet of 129 subjects were registered using a footscan((R)) pressure plate while the subjects jogged barefoot at a comfortable self-selected pace. Throughout the program 10 subjects sustained Achilles tendinopathy of which three reported bilateral complaints. Sixty-six subjects were excluded from the statistical analysis. Therefore the statistical analysis was performed on the remaining sample of 63 subjects. Logistic regression analysis revealed a significant decrease in the total posterior-anterior displacement of the Centre Of Force (COF) (P=0.015) and a laterally directed force distribution underneath the forefoot at 'forefoot flat' (P=0.016) as intrinsic gait-related risk factors for Achilles tendinopathy in novice runners. These results suggest that, in contrast to the frequently described functional hyperpronation following a more inverted touchdown, a lateral foot roll-over following heel strike and diminished forward force transfer underneath the foot should be considered in the prevention of Achilles tendinopathy.
Logistic regression analysis revealed a significant decrease in the total posterior-anterior displacement of the Centre Of Force (COF) (P=0.015) and a laterally directed force distribution underneath the forefoot at 'forefoot flat' (P=0.016) as intrinsic gait-related risk factors for Achilles tendinopathy in novice runners.
Did anyone read the paper? Did they examine what is meant by a decrease in the total posterior-anterior displacement of the Centre Of Force . Is this a midfoot/forefoot striker?