Chronic ankle instability (CAI) patients show various sensorimotor deficits, which may be related to the chronic nature of instability. Ultimately, an intervention should focus on deficits which may perpetuate the problem, but an understanding of successful sensorimotor function may best come from those who sprained their ankles with no problematics outcome (copers). PURPOSE: To examine sagittal ankle angles, moments, tibialis anterior and medial gastrocnemius EMG activation during a single-leg maximal vertical side-cutting jump task. METHODS: 66 subjects (M=42, F=24; 22.2±2 yrs, 173.8±8 cm, 71.4±11 kg) consisted of 22 CAI (77.1±15.3% FAAM ADL, 62.5±20.4% FAAM Sports, 4.1±2.8 sprains), 22 Copers (100% FAAM ADL & Sports, 2.0±1.1 sprains), and 22 healthy controls. Subjects performed 10 jumps, consisting of a max vertical jump, landing on a force plate, and transitioning immediately to a side-cutting jump, while the dependent variables were collected during stance. Functional linear models (α=.05) were used to detect mean difference between groups. If functions and associated 95% confidence intervals did not cross the zero, then significant differences existed. RESULTS: Figure 1 shows that copers and AI exhibited up to 2.5° less dorsiflexion angle during 30-75% of stance, relative to controls. While copers exhibited similar neuromechanics to controls in sagittal ankle moment, tibialis anterior and medial gastrocnemius EMG activation, those with CAI demonstrated up to 0.5 Nm/kg less plantarflexion moment, 2.5% less tibialis anterior and 47% less medial gastrocnemius EMG activation. CONCLUSION: Copers show neuromechanics similar to healthy controls at times, and similar to those with CAI at others. Reduced plantarflexion moment and medial gastrocnemius EMG activation suggest that those with CAI may rely more on static stabilizers (e.g., bones) than dynamic stabilizers (e.g., muscles), which could increase impact loads on tibiotalar cartilage surface.
In the current study, we aimed to determine if differences in drop jump height or motor task execution strategy between young and middle-aged adults exist, when triceps surae MTU capacities (muscle strength and tendon stiffness) were matched.
The triceps surae MTU biomechanical properties of 29 middle-aged and 26 younger adults were assessed during isometric voluntary ankle plantarflexion contractions of the dominant leg using a custom-made dynamometer and ultrasonography simultaneously. The 12 young adults with the lowest triceps surae muscle strength and the 12 middle-aged adults with the greatest muscle strength then completed a series of drop jumps from different heights. Ground contact time, average vertical ground reaction force, average mechanical power and jumping height were recorded.
Younger and middle-aged adults attained comparable jumping heights independent of the drop jump height. There were significant age effects on ground contact time and average vertical ground reaction force during ground contact phase, with the middle-aged adults showing higher ground contact times but lower forces, leading to a significant age effect on mechanical power. Significant correlations were found between triceps surae MTU capacities and drop jump height.
The results of the current study demonstrate that when triceps surae MTU capacities are matched, young and middle-aged adults show comparable performance of a jumping task, despite having different motor strategies. Finally, the results suggest that neuromuscular factors other than maximum isometric strength and tendon stiffness may influence motor task execution strategy during jumping.
In the following project, we explored the relationships between age, vestibulopathy and stability control, in order to determine the age and vestibulopathy-related effects on stability control, and to establish if a relationship existed between static and dynamic stability task performance. The first study examined the response to repeated trip perturbations of healthy middle aged adults and vestibulopathy patients, the second examined feedforward adaptation of gait in young, middle aged and older adults to a sustained mechanical perturbation and the third examined the relationship between standing balance and recovery following a tripping perturbation in vestibulopathy patients. The results showed that vestibulopathy is related to a diminished ability to control and recover gait stability after an unexpected perturbation, and to a deficient reactive adaptation potential. With ageing, the ability to recalibrate locomotor commands to control stability is preserved, although this recalibration may be slower in old age compared to middle and young age. Given that a decline in vestibular function is seen with increasing age, we suggest that assessment of vestibular function may be necessary when investigating locomotor stability and falls risk in both research and clinical settings. Finally, despite static balance tasks and parameters being commonly used in clinical settings, we did not find a consistent relationship between static and dynamic stability task performance, indicating the importance of dynamic stability tests when assessing falls risk in clinical settings.
The Force and Motion Foundation Updates...
The Force and Motion Foundation UPDATE!
The Force and Motion Foundation is proud to announce that our current $10,000 scholarship will be awarded in cooperation with the Orthopaedic Research Society (ORS).
The deadline for applications is December
Please visit http://www.ors.org/blog/2015/11/24/young-scientist-scholarship/ for more information on the Force & Motion Foundation/ ORS Young Scientist Scholarship.
2016 3rd Quarter recipients of the travel awards are: S. Jun Son, Matthias König, Christopher McCrum, Paige Lin, Danial Sharifi Kia, Kenneth Smale, Bryon Applequist
Submit your 4th Quarter Scientific Poster NOW for the F&M $500 Travel Scholarship!
Please check back in the future for information on more scholarship offers