912 research outputs found
A biomechanical analysis of plantar fasciitis using digital fluoroscopy
No full textPlantar fasciitis is the most common disorder of the foot and is characterised by pain involving the inferomedial aspect of the heel that is exacerbated by activity after periods of non-weightbearing. Despite an abundance of anecdotal evidence indicating that aberrant function of the foot is an aetiological factor in the development of plantar heel pain, there is little scientific evidence linking abnormal arch mechanics with plantar fasciitis. The primary purpose of this thesis was to investigate the biomechanics of plantar fasciitis by evaluating the sagittal plane kinematics and kinetics of the medial longitudinal arch during gait. Specifically, a low-dose motion X-ray technique, known as digital fluoroscopy, was used to evaluate the sagittal plane kinematics of the arch and a capacitance-based pressure plate was used to determine regional vertical ground reaction forces acting on the sole of the foot during gait.\ud
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Since digital fluoroscopy has not been widely used in gait analysis, the methodological phase of this study concentrated on identifying and quantifying the inherent limitations and potential errors in employing fluoroscopy as a gait analysis technique. In particular, the methodological phase evaluated the potential impact of the physical restrictions of the equipment on gait and the acquisition of gait data, as well as the magnitude of the distortion errors inherent in fluoroscopic images of the medial longitudinal arch. The findings indicate that digital fluoroscopy may be effectively used as a two-dimensional motion analysis technique for the evaluation of movement of the medial longitudinal arch during walking. The methodological studies demonstrate that the structural limitations of modem fluoroscopic systems are unlikely to substantially influence the acquisition of gait data. However, out-ofplane motion of osseous segments of the foot and the temporal response of the imaging system represent the major shortcomings of employing fluoroscopy as a gait analysis tool. Tests conducted on foot models and in vivo indicated that the application of published dist01iion correction procedures provided a method that is highly repeatable, with fluoroscopic image enors constituting less than 5 percent of the movement range.\ud
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In the experimental phase of this thesis, a digital fluoroscope and a pressure platform were used to evaluate the kinematics and kinetics of the medial longitudinal arch in people with and without plantar fasciitis. While pressure analysis demonstrated that patients with plantar fasciitis make gait adjustments that reduce the level of force beneath the rearfoot and forefoot of the symptomatic foot, fluoroscopy indicated that neither the dynamic shape nor the motion of the medial longitudinal arch differed between subjects with and without heel pain. Consequently, abnonnal arch shape and motion are not associated with the progression of plantar fasciitis. The peak arch angle was, however, positively correlated to the increased fascial thickness that was prototypic of plantar fasciitis. Thus, arch mechanics may play an important secondary role in plantar fasciitis by modifying the severity of heel pain, once present. In addition, increased loading and flexion of the digits was observed in patients with heel pain, suggesting that digital function plays an important, and previously unidentified, protective role in plantar fasciitis by bracing the medial longitudinal arch and thereby reducing the loading in the plantar fascia. The findings also suggest that plantar fasciitis may represent a bilateral process and raise questions regarding the rationale behind current treatments aimed at modifying the mechanics of the medial longitudinal arch in heel pain
Arch indexes from ink footprints and pressure platforms are different
No full textFootprints from force sensitive resistor (FSR) type pressure platforms have been shown to differ from ink prints, leading to a relative distortion of the arch index (AI). This study aimed to compare the accuracy of the AI derived from a capacitance pressure platform relative to ink footprints. Area measurements (heel, midfoot, forefoot, hallux and lesser toes) were acquired simultaneously from ink footprints and a pressure platform. Difference between paired values revealed relative measurement error. The platform overestimated heel area (2.2%), but underestimated midfoot area (10.2%), and lesser toe area (17.7 %). The mean AIs were 0.206 (platform) and 0.230 (ink prints). The pressure platform closely estimated contact areas for the heel and forefoot. Midfoot areas were underestimated sufficiently to bias the AI towards lower values. Therefore, the AI derived from a capacitance pressure platform is not the same as that from an ink footprint, and the two should not be used interchangeably. Feet classified according to AI from a pressure platform may be categorised differently than they would by using ink footprints. Pressure platform data cannot be used to determine AI with confidence until relative measurement error for isolated foot regions has been determined, or appropriate normative values established
A Comparison of Footprint Indexes Calculated From Ink and Electronic Footprints
No full textPressure platforms offer the potential to measure and record electronic footprints rapidly; however, the accuracy of geometric indexes derived from these prints has not been investigated. A comparison of conventional ink footprints with simultaneously acquired electronic prints revealed significant differences in several geometric indexes. The contact area was consistently underestimated by the electronic prints and resulted in a significant change in the arch index. The long plantar angle was poorly correlated between techniques. This study demonstrated that electronic footprints, derived from a pressure platform, are not representative of the equivalent ink footprints and, consequently, should not be interpreted with reference to literature on conventional footprints. (J Am Podiatr Med Assoc 91(4): 203-209, 2001
Achilles tendinopathy has an aberrant strain response to eccentric exercise
No full textPurpose: Eccentric exercise has become the treatment of choice for Achilles tendinopathy. However, little is known about the acute response of tendons to eccentric exercise or the mechanisms underlying its clinical benefit. This research evaluated the sonographic characteristics and acute anteroposterior (AP) strain response of control (healthy), asymptomatic, and symptomatic Achilles tendons to eccentric exercise. \ud
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Methods: Eleven male adults with unilateral midportion Achilles tendinopathy and nine control male adults without tendinopathy participated in the research. Sagittal sonograms of the Achilles tendon were acquired immediately before and after completion of a common eccentric rehabilitation exercise protocol and again 24 h later. Tendon thickness, echogenicity, and AP strain were determined 40 mm proximal to the calcaneal insertion. \ud
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Results: Compared with the control tendon, both the asymptomatic and symptomatic tendons were thicker (P < 0.05) and hypoechoic (P < 0.05) at baseline. All tendons decreased in thickness immediately after eccentric exercise (P < 0.05). The symptomatic tendon was characterized by a significantly lower AP strain response to eccentric exercise compared with both the asymptomatic and control tendons (P < 0.05). AP strains did not differ in the control and asymptomatic tendons. For all tendons, preexercise thickness was restored 24 h after exercise completion. \ud
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Conclusions: These observations support the concept that Achilles tendinopathy is a bilateral or systemic process and structural changes associated with symptomatic tendinopathy alter fluid movement within the tendon matrix. Altered fluid movement may disrupt remodeling and homeostatic processes and represents a plausible mechanism underlying the progression of tendinopathy
Design and Test of a Custom Instrumented Leg Press for Injury and Recovery Intervention
No full textThere is an increasing desire and emphasis to integrate assessment tools into the everyday training environment of athletes. These tools are intended to fine-tune athlete development, enhance performance and aid in the development of individualised programmes for athletes. The areas of workload monitoring, skill development and injury assessment are expected to benefit from such tools. This paper describes the development of an instrumented leg press and its application to testing leg dominance with a cohort of athletes. The developed instrumented leg press is a 45࠲eclining sled-type leg press with dual force plates, a displacement sensor and a CCD camera. A custom software client was developed using C#. The software client enabled near-real-time display of forces beneath each limb together with displacement of the quad track roller system and video feedback of the exercise. In recording mode, the collection of athlete particulars is prompted at the start of the exercise, and pre-set thresholds are used subsequently to separate the data into epochs from each exercise repetition. The leg press was evaluated in a controlled study of a cohort of physically active adults who performed a series of leg press exercises. The leg press exercises were undertaken at a set cadence with nominal applied loads of 50%, 100% and 150% of body weight without feedback. A significant asymmetry in loading of the limbs was observed in healthy adults during both the eccentric and concentric phases of the leg press exercise (P < .05). Mean forces were significantly higher beneath the non-dominant limb (4-10%) and during the concentric phase of the muscle action (5%). Given that symmetrical loading is often emphasized during strength training and remains a common goal in sports rehabilitation, these findings highlight the clinical potential for this instrumented leg press system to monitor symmetry in lower-limb loading during progressive strength training and sports rehabilitation protocols.Full Tex
Child transport practices and perceived barriers in active commuting to school
No full textThis study evaluated the transport practices of school children and perceived factors that influenced parental decisions regarding their child's use of active transport to commute to school. A self-administered parental questionnaire (n = 324) was used to determine the transport practices of school children and factors that influence parental decisions regarding their child's use of active transport to school. The relationship between transportation modes (active vs. passive), distance and descriptive variables were evaluated. Despite a median commuting distance of 2.5 km (0.1-28.0 km), only one-third of school trips involved active transport. Children using active transport commuted shorter distances (1.5 vs. 3.6 km), were older (10 vs. 8 years) and more likely to be male than those using motorised transport (P < 0.05). While logistic regression revealed only commuting distance was significantly associated with an increased odds of active transport (OR 0.29, 95% CI 0.17-0.48), the most frequently reported factors influencing parental decisions regarding their child's use of active transport were: (1) the age of child; (2) provision of safe walking paths; (3) adult supervision; (4) commuting distance, and (5) child's fitness level. While the majority of these factors have been identified within the literature, their validity has yet to be established
Validation of the intensity of walking for pleasure in obese adults
No full textDespite evidence that 'walking for pleasure' represents the most common leisure-time physical activity, the exercise intensity associated with 'walking for pleasure' in the obese has not been established. Heart rate (HR), perceived exertion (RPE) and walking speed were assessed for 30 obese and 20 non-obese adults as they completed two 2 km-walk tests on alternate days and were compared with a third 2 km walk with subjects walking 'as fast as possible'. Despite both obese (O) and non-obese (NO) groups rating the intensity of 'walking for pleasure' as 'light', HR and RPE data for only the NO group complied with definitions of 'light' intensity effort. 'Walking for pleasure' was characterised by a higher absolute (15 bpm, P < 0.05) and relative (70% of predicted maximum, P < 0.01) HR in the O group, which was representative of the transition between 'moderate' and 'hard' intensity exercise. The findings in the third, maximal trial were comparable across groups for all variables. Adiposity exerts a relative elevation-of-intensity effect on the cardiovascular system at walking speeds consistent with 'walking for pleasure'. 'Walking for pleasure' is sufficient to improve cardiovascular fitness in obese, but not normal-weight, individuals
Stanley Scott
No full textIn this black and white photograph, Presidential aid to Nixon and Ford, Stanley Scott is shown standing in front of the Executive Residence\u27s southern facade with a semi-circular portico facing the south lawn of the White House in Washington, D. C. Stanely is shown wearing a light colored checked suit with a dark necktie and a striped shirt and wire-rimmed eyeglasses.https://scholarsjunction.msstate.edu/mss-wilson-minor-photographs/1515/thumbnail.jp
Incidental walking activity is sufficient to induce time-dependent conditioning of the Achilles tendon
No full textThe Achilles tendon has been seen to exhibit time-dependent conditioning when isometric muscle actions were of a prolonged duration, compared to those involved in dynamic activities, such as walking. Since, the effect of short duration muscle activation associated with dynamic activities is yet to be established, the present study aimed to investigate the effect of incidental walking activity on Achilles tendon diametral strain. Eleven healthy male participants refrained from physical activity in excess of the walking required to carry out necessary daily tasks and wore an activity monitor during the 24 h study period. Achilles tendon diametral strain, 2 cm proximal to the calcaneal insertion, was determined from sagittal sonograms. Baseline sonographic examinations were conducted at approximately 08:00 h followed by replicate examinations at 12 and 24 h. Walking activity was measured as either present (1) or absent (0) and a linear weighting function was applied to account for the proximity of walking activity to tendon examination time. Over the course of the day the median (min, max) Achilles tendon diametral strain was -11.4 (4.5, -25.4)%. A statistically significant relationship was evident between walking activity and diametral strain (P<0.01) and this relationship improved when walking activity was temporally weighted (AIC 131 to 126). The results demonstrate that the short yet repetitive loads generated during activities of daily living, such as walking, are sufficient to induce appreciable time-dependant conditioning of the Achilles tendon. Implications arise for the in vivo measurement of Achilles tendon properties and the rehabilitation of tendinopathy
Why forefoot striking in minimal shoes might positively change the course of running injuries
No full textIt is believed that human ancestors evolved the ability to run bipedally approximately 2 million years ago. This form of locomotion may have been important to our survival and likely has influenced the evolution of our body form. As our bodies have adapted to run, it seems unusual that up to 79% of modern day runners are injured annually. The etiology of these injuries is clearly multifactorial. However, 1 aspect of running that has significantly changed over the past 50 years is the footwear we use. Modern running shoes have become increasingly cushioned and supportive, and have changed the way we run. In particular, they have altered our footstrike pattern from a predominantly forefoot strike (FFS) landing to a predominantly rearfoot strike (RFS) landing. This change alters the way in which the body is loaded and may be contributing to the high rate of injuries runners experience while engaged in an activity for which they were adapted. In this paper, we will examine the benefits of barefoot running (typically an FFS pattern), and compare the lower extremity mechanics between FFS and RFS. The implications of these mechanical differences, in terms of injury, will be discussed. We will then provide evidence to support our contention that FFS provides an optimal mechanical environment for specific foot and ankle structures, such as the heel pad, the plantar fascia, and the Achilles tendon. The importance of footwear will then be addressed, highlighting its interaction with strike pattern on mechanics. This analysis will underscore why footwear matters when assessing mechanics. Finally, proper preparation and safe transition to an FFS pattern in minimal shoes will be emphasized. Through the discussion of the current literature, we will develop a justification for returning to running in the way for which we were adapted to reduce running-related injuries
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