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Anthropometric and sensory factors influence perception of footwear comfort

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In a series of prospective studies among infantry recruits the biomechanics of stress fractures have been studied. In this recruit model bone geometry and the natural shock absorbers of the body have been found to be related to stress fracture morbidity. Using the technique of accelerometry in this model, it has been shown that in the fatigue state shock absorption decreases, resulting in an increase in the amplitude of vertical accelerations that propagate up the skeleton at heel strike. Experiments to study the possibility of lowering stress fracture morbidity in this model by means of viscoelastic orthotics have been successful only in the case of femoral and metatarsal stress fractures among certain subpopulations. Stress fracture management in this model has been improved by early detection and by treatment regimens according to a protocol that emphasizes limited rest periods to allow healing to take place rather than judging recovery by pain levels.
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This review article describes shoe inserts and provides information to assist physical therapists to identify patients who may benefit from foot orthoses. The article discusses goals for and types of shoe inserts, in addition to the materials and methods that can be used in fabricating appliances. Clinical considerations for the use of shoe inserts and application to specific patient populations are presented.
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As the number of runners has increased dramatically, so has the incidence of running-related injuries. In order to determine what training factors are associated with running-related injuries, as well as what percentage of injured runners seeks professional medical attention, a random sample of entrants to a 10 kilometer race was asked to complete a questionnaire. There were 451 respondents, 355 men and 96 women, with a nonresponse rate of 12.7%. Nonrespondents did not differ from respondents with regard to age or sex. Forty-seven percent of respondents indicated that they had sustained a running-related injury in the last 2 years. Injured runners differed significantly from noninjured runners in that they were more likely to have run more miles per week, run more days per week, run a faster pace, run more races in the last year, stretched before running, and not participated regularly in other sports. Associated with injury, but not statistically significant, were those who had run marathons and had done muscle-strengthening exercises. No association was found with regard to the length of time running, running surfaces, part of the foot first contacting the ground, or running intervals, sprints, or hills. Seventy percent of those injured sought professional medical care, with 76% of these having a good or excellent recovery from their injuries. Compliance with medical advice correlated well with treatment success.
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Visual analogue scales (VAS) of sensory intensity and affective magnitude were validated as ratio scale measures for both chronic and experimental pain. Chronic pain patients and healthy volunteers made VAS sensory and affective responses to 6 noxious thermal stimuli (43, 45, 47, 48, 49 and 51 degrees C) applied for 5 sec to the forearm by a contact thermode. Sensory VAS and affective VAS responses to these temperatures yielded power functions with exponents 2.1 and 3.8, respectively; these functions were similar for pain patients and for volunteers. The power functions were predictive of estimated ratios of sensation or affect produced by pairs of standard temperatures (e.g. 47 and 49 degrees C), thereby providing direct evidence for ratio scaling properties of VAS. Vas sensory intensity responses to experimental pain, VAS sensory intensity responses to different levels of chronic pain, and direct temperature (experimental pain) matches to 3 levels of chronic pain were all internally consistent, thereby demonstrating the valid use of VAS for the measurement of and comparison between chronic pain and experimental heat pain.
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Although foot orthotics are often prescribed to alter the lower-extremity mechanics during the stance period of gait, there is little documentation of the actual effect of foot orthotics on the movement of the lower-extremity joints during walking and running. This study examined the effect of foot orthotics on the range of motion of the talocrural/subtalar joint and the knee joint in three dimensions during walking and running. Ten female adolescent subjects, aged 13 to 17 years (X = 14.4, SD = 1.1) who were diagnosed with patellofemoral pain syndrome and exhibited forefoot varus greater than 6 degrees and/or calcaneal valgus greater than 6 degrees participated in the study. Thirty strides of walking and running on a treadmill were recorded for each of the orthotic and nonorthotic conditions for each subject using an optoelectronic recording technique. Analyses of variance for repeated measures were performed on the range of motion of the talocrural/subtalar joint and knee joint for each plane of motion (ie, six separate analyses). The main factors of each analysis were the effect of the orthotic (orthotic condition versus nonorthotic condition), mode of ambulation (walking and running), and phase of the stance period (contact, mid-stance, and propulsion). No differences were found in sagittal-plane movements. Reductions of 1 to 3 degrees occurred with orthotic use for the talocrural/subtalar joint during walking and running in the frontal and transverse planes. The orthotics reduced knee motion in the frontal plane during the contact and mid-stance phases of walking, but increased the motion during the contact and mid-stance phases of running. This study shows that corrections to the static position of forefoot varus and calcaneal valgus can result in changes in transverse- and frontal-plane motion of the foot and knee during walking and running.
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In conclusion, a functional orthosis may be used to effectively treat most, but not all, abnormalities of the lower extremity that cause abnormal function of the foot. Abnormalities that are resistant to treatment with functional orthoses are compensated talipes equinus, excessive verticality of the oblique axis of the midtarsal joint, forefoot adductus that exceeds 15 degrees of adductus, Charcot's disease, congenital shortage of the iliopsoas muscle, and certain neurologic diseases that exhibit transient muscle spasm or paralysis, resulting in abnormal forces acting upon the foot that vary with time. Unfortunately, laboratories that claim to fabricate functional orthoses may turn out products that vary from nondescript arch supports to orthoses that only partially control function of the foot. The author hopes the practitioner who reads this article will be better able to evaluate whether his or her laboratory is providing his or her patient with a functional orthosis when one is ordered.
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In quantitative sensory testing, certain methods may lead to incorrect estimates of vibratory (VDT), cool (CDT), or warm (WDT) detection thresholds. We have shown that the specific forced-choice algorithm of testing employed in our Computer-Assisted Sensory Examination (CASE IV) system, when compared with other tests of nerve dysfunction, provides accurate and reproducible estimates of these thresholds. Because this forced-choice algorithm is time consuming and performance might be made worse by drowsiness or boredom, we explored other algorithms that might provide estimates of threshold similar to those obtained with the forced-choice algorithm, but more quickly. In a trial of 25 healthy subjects and 25 patients with neuropathy, the 4, 2, and 1 stepping algorithm with null stimuli, based in part on comparative data from computer simulation and insights from patient decision making, provides an accurate estimate of threshold. On average, the time needed for forced-choice testing was 12.8 +/- 2.9 minutes (mean +/- SD). For 4, 2, and 1 stepping testing, it was 2.7 +/- 2.5 minutes--a large saving of time. Since null stimuli were employed in the 4, 2, and 1 stepping algorithm, it was possible to monitor for spurious responses and repeat the test if they occurred at an excessive rate. The algorithm appears to be sufficiently robust to be recommended for clinical use and for some controlled clinical and epidemiologic trials.
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Lower limb injuries present the greatest source of medical problems during basic military training. These main overuse lower limb injuries, anterior compartment syndrome, stress fractures, Achilles tendinitis, plantar fasciitis, shin splints, and chondromalacia patellae, are reviewed with respect to current knowledge of rates, diagnosis, and treatment. Part 2 shall review possible etiological factors involved in the causation of these injuries.
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Soccer referees participating in large soccer tournaments may develop overuse injuries. In this study the effect of shock absorbing heel inserts in the incidence of soreness was investigated. Forty-eight referees were randomly selected to wear shock absorbing heel inserts (SAH) in the 5 day-tournament, while 43 referees were the control group. A daily questionnaire inquiring about complaints from the locomotive system was completed for each referee and in case of any soreness they were examined by doctors to document and classify the anatomical site. Calf, thigh, back, achilles tendon and knee were the most common localizations of overuse symptoms. The incidence of soreness in achilles tendon, calf and back were significantly reduced by the use of (SAH) inserts.
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A group of 304 runners enrolling in a marathon training program had alignment measurements performed and completed a questionnaire on training practices and injuries over the previous 12 months. The alignment measures consisted of arch index (AI), heel valgus (HV), knee tubercle-sulcus angle (TSA), knee varus (KV), and leg-length difference (LLD). Results indicated few consistent statistical associations between these alignment measures and risk of injuries, either bivariately or multivariately: left AI with hamstring injuries; right AI with shin injuries; right HV with back injuries; left TSA with ankle injuries; KV with hip injuries; and LLD with back, ankle, and foot injuries. A few statistically significant relationships were also found between other training and anthropometric factors and injuries: mileage with hamstring injuries; interval training with shin injuries; hard surfaces with back and thigh injuries; shoe use patterns with foot and overall injuries; and body mass index with heel injuries. We conclude that lower-extremity alignment is not a major risk factor for running injuries in our relatively low mileage cohort; however, prospective studies are necessary to confirm or refute these findings.
Article
The purposes of this paper were to discuss the perceived benefits of inserts and orthotics for sport activities and to propose a new concept for inserts and orthotics. There is evidence that inserts or orthotics reduce or prevent movement-related injuries. However, there is limited knowledge about the specific functioning an orthotic or insert provides. The same orthotic or insert is often proposed for different problems. Changes in skeletal movement due to inserts or orthotics seem to be small and not systematic. Based on the results of a study using bone pins, one may question the idea that a major function of orthotics or inserts consists in aligning the skeleton. Impact cushioning with shoe inserts or orthotics is typically below 10%. Such small reductions might not be important for injury reduction. It has been suggested that changes in material properties might produce adjustments in the muscular response of the locomotor system. The foot has various sensors to detect input signals with subject specific thresholds. Subjects with similar sensitivity threshold levels seem to respond in their movement pattern in a similar way. Comfort is an important variable. From a biomechanical point of view, comfort may be related to fit, additional stabilizing muscle work, fatigue, and damping of soft tissue vibrations. Based on the presented evidence, the concept of minimizing muscle work is proposed when using orthotics or inserts. A force signal acts as an input variable on the shoe. The shoe sole acts as a first filter, the insert or orthotic as a second filter, the plantar surface of the foot as a third filter for the force input signal. The filtered information is transferred to the central nervous system that provides a subject specific dynamic response. The subject performs the movement for the task at hand. For a given movement task, the skeleton has a preferred path. If an intervention supports/counteracts the preferred movement path, muscle activity can/must be reduced/increased. Based on this concept, an optimal insert or orthotic would reduce muscle activity, feel comfortable, and should increase performance.
Article
Objective: To quantify the relationship between the tactile and vibration sensitivity thresholds of the sole of the human foot with plantar pressure distribution while walking and running. Design: Cross-sectional study performed in a laboratory setting. Background: Results of previous studies of human locomotion have identified potentially dangerous variations in locomotion patterns. A common approach to manage these variations is with the use of orthotics. Individual responses to differences in the construction and shape of orthotics cannot be fully explained with a mechanical model. It has been suggested that sensory feedback from the receptors in the feet may play an important role in regulating gait patterns. Methods: Fifteen subjects were recruited for this study. Pressure (tactile) and vibration thresholds were determined from each subject. Plantar pressure distributions were obtained while walking at 1.5 m s(-1) and running at 3.5 m s(-1). Sensitivity measurements were correlated to pressure measurements under the foot. Results: Significant negative correlation exists between the vibration threshold of the hallux at 125 Hz and peak pressures under the hallux while walking (P=0.02) and running (P=0.01). A significant negative relationship was shown between the foot mean vibration threshold at 125 Hz with peak force during running (P=0.038). A similar trend was seen at the heel, lateral arch and first metatarsal head. Conclusions: The results from this study support recent hypotheses that suggest that the body can detect and respond to external stimuli. The relationship between plantar sensitivity and peak pressures at the hallux, and the relationship between sensitivity to higher frequency vibrations and peak force during running suggests that neurological feedback should be incorporated in to any model that attempts to explain gait patterns. Relevance: It is suggested that the body is able to detect small biomechanical changes in the external environment and alter gait patterns as a defensive mechanism. Understanding the relationship between neural feedback and gait patterns will help in the development of criteria for the proper application of inserts, and the prevention of lower extremity injuries.
Article
To quantify the effects of medial foot orthoses on skeletal movements of the calcaneus and tibia during the stance phase in running. Kinematic effects of medial foot orthoses (anterior, posterior, no support) were tested using skeletal (and shoe) markers at the calcaneus and tibia. Previous studies using shoe and skin markers concluded that medially placed orthoses control/reduce foot eversion and tibial rotation. However, it is currently unknown if such orthoses also affect skeletal motion at the lower extremities. Intracortical Hofman pins with reflective marker triads were inserted under standard local anesthetic into the calcaneus and tibia of five healthy male subjects. The three-dimensional tibiocalcaneal rotations were determined using a joint coordinate system approach. Eversion (skeletal and shoe) and tibial rotation were calculated to study the foot orthoses effects. Orthotic effects on eversion and tibial rotations were found to be small and unsystematic over all subjects. Differences between the subjects were significantly larger (p<0.01; up to 10 degrees ) than between the orthotic conditions (1-4 degrees ). Significant orthotic effects across subjects were found only for total internal tibial rotation; p<0.05). This in vivo study showed that medially placed foot orthoses did not change tibiocalcaneal movement patterns substantially during the stance phase of running. Orthoses may have only small kinematic effects on the calcaneus and tibia (measured with bone pins) as well as on the shoes (measured with shoe markers) during running of normal subjects. Present results showed that orthotic effects were subject specific and unsystematic across conditions. It is speculated that orthotic effects during the stance phase of running may be mechanical as well as proprioceptive.
Article
The purpose of this study was to determine the relationships between foot and leg characteristics, shoe characteristics, and the short-term subjective comfort of three different pairs of athletic shoes. Static measurements of foot dimension and leg angles were taken from eighteen subjects. Subjects rated the comfort of three different athletic shoes for standing, walking and running. The shoes were quantified by internal dimensions, hardness, flexibility and torsional stiffness. Average comfort ratings decreased from standing to walking to running. One shoe seemed suited for only a small group of subjects. In contrast, another shoe was generally comfortable for a large group. Skeletal alignment, specifically eversion angle, was related to comfort for one shoe. Therefore, fit of the shoe is not sufficient for comfort. Skeletal alignment, shoe torsional stiffness and cushioning seem to be mechanical variables which may be important for comfort.
Article
OBJECTIVE: Perceptual ratings of mechanical variables were compared with biomechanical variables that are related to running injuries. DESIGN: Eight identical running shoes with a relatively close range of midsole hardness were used. Ground reaction force (GRF), in-shoe pressure distribution and rearfoot motion were measured during running. Perceptual ratings were obtained after the running trials. BACKGROUND: Previous studies reported high correlations between cushioning perception and biomechanical variables for shoes that featured large differences in midsole hardness. METHODS: A 15-point categorical rating scale was used to judge impact severity, pressure magnitude and rearfoot motion in running. Rating scores were compared with biomechanical variables (GRF, pressure distribution and pronation values) using regression analyses. RESULTS: Regression analyses revealed high relations between different biomechanical variables and the perception scores. The best relation to perception was analysed for the median power frequency of the vertical GRF (r(2) = 0.97). A negative correlation (r(2) = 0.54) between the first impact of GRF and the perception of impact severity could be revealed. CONCLUSION: The present study suggests that the body's sensory system seems to differentiate well between impacts of different frequency content. Based on perceptual abilities, subjects adapt their running style to avoid high heel impacts.
A review of lower limb overuse injuries during basic military training Part 1: types of overuse injuries Prevention of common overuse injuries by the use of shock absorbing insoles
  • G Jordaan
  • T D Noakes
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The validation of visual analogue scales as ratio scale measures for chronic and experimental pain
  • D D Price
  • P A Mcgrath
  • A Rafic
  • B Buckingham
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