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This article discusses the physiological impact of exercise on injured ankles. An analysis of coordination, reaction time, joint position, and postural sway is presented.

A study examines whether a multistation proprioceptive exercise program prevents ankle injuries in basketball players. Results suggest that the multistation proprioceptive exercise program undertaken effectively prevents ankle injuries in basketball players.

Context:Various designs of braces including hinged and nonhinged models are used to provide external support of the ankle. Hinged ankle braces supposedly allow almost free dorsiflexion and plantar flexion of the foot in the sagittal plane. It is unclear, however, whether this additional degree of freedom affects the stabilizing effect of the brace in the other planes of motion.Objective:To investigate the dynamic and passive stabilizing effects of 3 ankle braces, 2 hinged models that provide free plantar flexion–dorsiflexion in the sagittal plane and 1 ankle brace without a hinge.Design:Crossover study.Setting:University Movement Analysis Laboratory.Patients or Other Participants:Seventeen healthy volunteers (5 women, 12 men; age 25.4 ± 4.8 years; height 180.3 ± 6.5 cm; body mass 75.5 ± 10.4 kg).Intervention(s):We dynamically induced foot inversion on a tilting platform and passively induced foot movements in 6 directions via a custom-built apparatus in 3 brace conditions and a control condition (no brace).Main Outcome Measure(s):Maximum inversion was determined dynamically using an in-shoe electrogoniometer. Passively induced maximal joint angles were measured using a torque and angle sensor. We analyzed differences among the 4 ankle-brace conditions (3 braces, 1 control) for each of the dependent variables with Friedman and post hoc tests (P< .05).Results:Each ankle brace restricted dynamic foot-inversion movements on the tilting platform as compared with the control condition, whereas only the 2 hinged ankle braces differed from each other, with greater movement restriction caused by the Ankle X model. Passive foot inversion was reduced with all ankle braces. Passive plantar flexion was greater in the hinged models as compared with the nonhinged brace.Conclusions:All ankle braces showed stabilizing effects against dynamic and passive foot inversion. Differences between the hinged braces and the nonhinged brace did not appear to be clinically relevant.

Everyone's walking style is unique, and it has been shown that both humans and computers are very good at recognizing known gait patterns. It is therefore unsurprising that dynamic foot pressure patterns, which indirectly reflect the accelerations of all body parts, are also unique, and that previous studies have achieved moderate-to-high classification rates (CRs) using foot pressure variables. However, these studies are limited by small sample sizes (n< 30), moderate CRs (CR ≃ 90%), or both. Here we show, using relatively simple image processing and feature extraction, that dynamic foot pressures can be used to identify n= 104 subjects with a CR of 99.6 per cent. Our key innovation was improved and automated spatial alignment which, by itself, improved CR to over 98 per cent, a finding that pointedly emphasizes inter-subject pressure pattern uniqueness. We also found that automated dimensionality reduction invariably improved CRs. As dynamic pressure data are immediately usable, with little or no pre-processing required, and as they may be collected discreetly during uninterrupted gait using in-floor systems, foot pressure-based identification appears to have wide potential for both the security and health industries.

ObjectiveTo compose an inventory of instruments that have been described to measure foot function i.e., pressure andor gait parameters, foot pain, and footrelated disability in rheumatoid arthritis RA, and to investigate the clinimetric quality of these measures.MethodsA systematic search was conducted in Medline, CINAHL, EMBase, and Sportdiscus. Standardized criteria, extended with levels of evidence, were applied to assess the quality of the clinimetric studies and the properties i.e., reliability, validity, and responsiveness of the described instruments.ResultsA variety of measurement instruments were identified. Only 16 instruments have been studied for their measurement properties in RA patients: 7 for assessing foot function, 3 for measuring footrelated disability, and 6 for measuring both foot pain and footrelated disability. Thirteen instruments were rated for reliability, of which 10 were rated positively on different levels of evidence. No positive rating for absolute measurement error was applicable for any of the tests. Internal consistency was reported for 7 instruments; 3 assigned a positive rating. For 2 instruments, Rasch analysis was used to assess the methodologic quality. A positive rating was reported for goodnessoffit only, not for item calibration. Seven instruments were rated for construct validity, and 3 assigned a positive rating. Only 2 instruments were rated positively for responsiveness.ConclusionThis review offers a basis for choosing the most appropriate instruments for measuring foot function, foot pain, and footrelated disability in RA patients, both for clinical practice and for research. Further research on the quality of these measures is urgently needed.

The aim of the present investigation was to evaluate the stabilizing effect of 10 different ankle braces during simulated inversion on a tilting platform. Twenty-five subjects participated in the study (23±3 yrs, 71±12 kg, 177±9 cm). Ten commercially available ankle braces and a trapdoor in combination with a goniometer system that measured hindfoot inversion inside the shoe were used. Inversion was subdivided into a free fall and a maximum inversion phase. Results showed that all braces restricted inversion significantly between 51% and 15% compared to the no-brace condition but distinct differences between models were found. Maximum inversion angle and inversion velocity were lower for those braces that restricted inversion most effectively during the free fall phase. Reaction times of the peroneus longus did not appear to influence the degree of inversion. Relatively constant differences between free fall and maximum inversion angles for all models (between 6° and 10°) and a high correlation between these two parameters suggests that the main function of ankle braces is to restrict inversion during the free fall phase and not at the extremes of motion.

The present study investigated the effects of two different surgical procedures for the treatment of chronic ankle instability. Ten patients treated with an anatomic reconstruction using a periosteal flap were compared with a second group that received an Evans tenodesis. All patients were evaluated before and after surgery with clinical and radiographic examinations as well as dynamic pedobarography. Patient satisfaction and radiographic and functional results were comparable in both groups and revealed a good restoration of joint stability and gait symmetry. Our results indicate that both methods of ankle ligament reconstruction achieve a comparable clinical and functional outcome within 1 year after surgery.

The Evans tenodesis is an operative treatment for chronic ankle instability with good short-term results.18,24,25The disadvantage of impaired hind foot kinematics and restricted motion has been described,6,16and only few reports of long-term results can be found.14No techniques have been used to assess the outcome objectively. We wanted to determine whether a modified Evans procedure33led to a satisfactory clinical and functional outcome. Nineteen patients were available at a 10-year follow-up. The clinical examination included a detailed questionnaire and stress radiographs. Foot function was evaluated with plantar pressure distribution measurements during walking and peroneal reaction time measurements elicited on a rapidly tilting platform (recorded with surface electromyography). High subjective patient satisfaction was contrasted with a high rate of residual instability, pain, and swelling. The radiographs showed an increased number of exostoses. The gait analysis revealed reduced peak pressures under the lateral heel and increased values under the longitudinal arch. The reaction times of the peroneal muscles were shorter on the operated side (significant: peroneus longus). The persistent clinical problems as well as the functional changes indicate that the disturbed ankle joint kinematics permanently alter foot function and may subsequently support the development of arthrosis. Therefore, the Evans procedure should only be applied if anatomical reconstruction of the lateral ankle ligaments is not feasible.

Peak pressures and regional impulses were determined under the feet of 15 children and 111 adults by means of a capacitive pressure distribution platform. The measurements were taken during walking and running and revealed insights into foot function during the process of locomotion skill acquisition. Considerably reduced peak pressures in the infant group could be attributed to a softer foot structure and a lower body-weight to foot-contact area ratio. An almost three times higher relative load under the midfoot of the infant foot shows that the longitudinal foot arch is still a weak structure. Within a few months of gait development remarkable changes toward an adult loading pressure pattern were observed.

Peak pressures and relative loads were determined under the feet of 125 children between 6 and 10 years of age. These results were compared with previously published data from 111 adults. A capacitive pressure distribution platform with a resolution of 2 sensors/cm2was used for data collection during walking. As compared with the group of adults, the school children showed considerably lower peak pressures under all anatomical structures. Larger foot dimensions with respect to body weight result in reduced foot pressures for the children by distributing the ground reaction forces across larger contact areas. With increasing age, a medial load shift in the forefoot could be observed for the older children. Data analysis of the pressures under the midfoot revealed that the longitudinal foot arch development is almost complete before the age of 6. Contrary to the findings in adults, body weight was identified to be of major influence on the magnitude of the pressures under the feet of school children. No differences were found for the foot pressures between boys and girls.

We followed 38 patients with chronic ankle instability treated by a modified Evans procedure. Evaluation at an average of 68 months follow-up included a standard clinical questionnaire and examination, radiological procedures, and gait analysis. Plantar pressure distribution measurements were recorded during walking and were compared with data from a group of normal subjects (N = 100). The subjective patient questionnaire revealed 87% good or excellent results, but residual pain was reported by 40% of the patients. The gait analysis indicated a significant increase in midfoot loading (22%) consistent with an observed restriction of inversion after surgery. However, the plantar pressure changes were not associated with poor clinical outcome. We cannot say whether these increased pressures will be associated with long-term outcome.

HENNIG, E. M., D. ROSENBAUM, and T. L. MILANI. Transfer of tennis racket vibrations onto the human forearm. Med. Sci. Sports Exerc., Vol. 24, No. 10, pp. 1134–1140, 1992. One of several factors suspected in the development of lateral epicondylitis, often referred to as tennis elbow, is the impact-induced vibration of the racket-and-arm system at ball contact. Using two miniature accelerometers at the wrist and the elbow of 24 tennis players, the effects of 23 different tennis racket constructions were evaluated in a simulated backhand stroke situation. The influences of body weight, skill level, and tennis racket construction onto the magnitude of vibrations at wrist and elbow were investigated. Amplitudes, integrals, and fourier components were used to characterize arm vibration. More than fourfold reductions in acceleration amplitude and integral were found between wrist and elbow. Off-center as compared with center ball impacts resulted in approximately three times increased acceleration values. Between subjects, body weight as well as skill level were found to influence arm vibration. Compared with proficient players, a group of less skilled subjects demonstrated increased vibration loads on the arm. Between different racket constructions, almost threefold differences in acceleration values could be observed. Increased racket head size as well as a higher resonance frequency of the racket were found to reduce arm vibration. The vibration at the arm after ball impact showed a strong inverse relationship (r = s −0.88) with the resonance frequency of tennis rackets.

The aim of this study was to investigate the acute effects of prior exercise (warm-up and stretching) on the electromyographic and force output of mechanically elicited triceps surae reflexes. Fifty male subjects performed eight reflex experiments under each of three successive conditions in one session: (1) no prior exercise, (2) after static stretching of the passive triceps surae (3 min) and (3) after a 10-min warm-up run on a treadmill. Tendon tap reflex force was elicited in the triceps surae of the right leg by means of a standardized reflex hammer and measured in a custom-built fixture. Electromyographic (EMG) signals were recorded with surface electrodes over the medial head of the gastrocnemius (G) and the soleus (S). Low coefficients of variation within subjects contrasted with high between-subject variations, indicating highly individual reflex characteristics. After stretching, reductions in the peak force (-5%; P < 0.05), the force rise rate (-8%; P < 0.01), the half relaxation rate (-5%; N.S.), the EMG amplitudes (G, -16%; S, -17%; P < 0.01) and integrals (G, -15%; S, -18%; P < 0.01), and an increase in EMG latencies (G, +3%; S, +1%; P < 0.01), were found compared with the values obtained without prior exercise. After running, the peak force reached the values obtained without prior exercise (-2%; N.S.), the force rise rate and half relaxation rate increased by 8 and 12%, respectively (P < 0.01), and the impulse (force-time integral; -12%), EMG amplitudes (G, -20%; S, -23%; P < 0.01), integrals (G, -18%; S, -23%; P < 0.01) and latencies (G, -1%; S, -2%; P < 0.01) decreased significantly. The changes in the force characteristics observed after the stretching treatment indicate improved muscle compliance that might reduce the risk of injury. On the other hand, the changes after the additional warm-up run had a more pronounced influence with regard to improved force development and a decreased EMG activity, which can be viewed as a performance-enhancing effect.