Influence of a Functional Knee Brace and Exercise on Lower Extremity Kinematics During Jogging

ABSTRACT Context: Functional knee braces (FKB) are used prophylactically and in rehabilitation to aide in the functional stability of the knee joint. Objective: To determine if alterations in sagittal plane lower extremity kinematics remain evident throughout a one hour period in healthy individuals. Design: 2X5 repeated measures design. Setting: Biomechanics Laboratory. Subjects: Twenty subjects (14 male and 6 female, mean age 26.5±7 yrs; height 172.4±13 cm; weight 78.6±9 kg), separated into braced (B) and no brace (NB) groups. Intervention: A one-hour exercise program divided into three 20 minute increments. Main Outcome Measures: Synchronized three-dimensional kinematic data were collected at 20-minute increments to assess the effect of the FKB on select lower extremity joint kinematics. Results: Hip, knee and ankle joint position were not significantly affected by time (exercise). However significant decreases in hip (p = .05) and knee flexion (p \u3c .05) were noted in the B group compared to the NB group regardless of time while ankle joint position was unaffected. Conclusions: Hip and knee flexion angles were reduced in the B group compared to the NB group, while ankle joint position was not affected. Wearing a knee brace appears to not only influence knee joint position but also hip joint position. It is possible that repetitive changes to hip joint kinematics may be detrimental to hip and low back function and thus lead to injury

Lower extremity fatigue increases complexity of postural control during a single-legged stance

<p>Abstract</p> <p>Background</p> <p>Non-linear approaches to assessment of postural control can provide insight that compliment linear approaches. Control entropy (CE) is a recently developed statistical tool from non-linear dynamical systems used to assess the complexity of non-stationary signals. We have previously used CE of high resolution accelerometry in running to show decreased complexity with exhaustive exercise. The purpose of this study was to determine if complexity of postural control decreases following fatiguing exercise using CE.</p> <p>Methods</p> <p>Ten subjects (5 M/5 F; 25 ± 3 yr; 169.4 ± 11.7 cm; 79.0 ± 16.9 kg) consented to participation approved by Western Oregon University IRB and completed two trials separated by 2-7 days. Trials consisted of two single-legged balance tests separated by two Wingate anaerobic tests (WAnT; PreFat/PostFat), or rest period (PreRest/PostRest). Balance tests consisted of a series of five single-legged stances, separated by 30 s rest, performed while standing on the dominant leg for 15-s with the participant crossing the arms over the chest and flexing the non-dominant knee to 90 degrees. High resolution accelerometers (HRA) were fixed superficial to L3/L4 at the approximate center of mass (COM). Triaxial signals from the HRA were streamed in real time at 625 Hz. COM accelerations were recorded in g's for vertical (VT), medial/lateral (ML), and anterior/posterior (AP) axes. A newly developed statistic (R-test) was applied to group response shapes generated by Karhunen Loeve (KL) transform modes resulting from Control Entropy (CE) analysis.</p> <p>Results</p> <p>R-tests showed a significant mean vector difference (<it>p </it>< .05) within conditions, between axes in all cases, except PostFat, indicating the shape of the complexity response was different in these cases. R-test between conditions, within axis, differences were only present in PostFat for AP vs. PreFat (<it>p </it>< .05). T-tests showed a significantly higher overall CE PostFat in VT and ML compared to PreFat and PostRest (<it>p </it>< .0001). PostFat CE was also higher than PostRest in AP (<it>p </it>< .0001).</p> <p>Conclusions</p> <p>These data indicate that fatiguing exercise eliminates the differential complexity response between axes, but increases complexity in all axes compared to the non-fatigued condition. This has implications with regard to the effects of fatigue on strategies of the control system to maintain postural control.</p

Effects of training on postural control and agility when wearing socks of different compression levels

Study aim: The aim of this study was to evaluate the effects of training while wearing socks differing in compression level (clinical, sub-clinical, regular) on performance of static and dynamic balancing and agility tasks in healthy, physically active people. We sought to understand whether socks with different compression properties supported postural regulation and agility task performance by enhancing somatosensory perception, unskewed by specific age range effects. Material and methods: Participants comprised 61 adults aged 18-75 years, divided into three groups (two experimental groups wearing clinical or sub-clinical level compression socks, and one control group wearing regular non-compression socks during training). An 8-week (2 × 1h per week) intervention programme was administered to train static and dynamic balance and postural control, leg strength and agility. Results: A mixed model ANOVA revealed no differences in static and dynamic balance and postural control and agility performance between clinical, sub-clinical, and control groups before and after training. All groups significantly improved their test performance, suggesting that training had some benefit on motor performance. Conclusions: These results raised interesting questions requiring further investigation to examine the effects of wearing socks (with and without different levels of compression) on motor behaviours in specific groups of elderly vs. young participants, in physically active vs. less physically active people, and in performance settings outside standardized laboratory tests to study applications in natural performance environments

The effect of different skin-ankle brace application pressures on quiet single-limb balance and electromyographic activation onset of lower limb muscles

<p>Abstract</p> <p>Background</p> <p>Several studies have been carried out in order to investigate the effect of ankle bracing on ankle joint function and performance. However, no study so far has examined the role of skin-brace interface pressure in neuromuscular control. The aim of this study was to investigate the effect of different skin-ankle brace interface pressures on quiet single limb balance and the electromyographic (EMG) activation sequence of four lower limb muscles.</p> <p>Methods</p> <p>Thirty three male physical education students who volunteered to take part in the study were measured under three ankle brace conditions: i) without brace, ii) with brace and 30 kPa application pressure and iii) with brace and 60 kPa application pressure. Single limb balance (anteroposterior and mediolateral parameter) was assessed on the dominant lower limb, with open and closed eyes, on a force platform, simultaneously with the EMG recording of four lower lower limb muscles' (gastrocnemius, peroneus longus, rectus femoris and biceps femoris) activation onset.</p> <p>Results</p> <p>The results showed that overall balance (total stability parameter) was not significantly affected in any of the three ankle brace conditions. However, the anteroposterior centre of pressure excursion and centre of pressure excursion velocity were significantly increased with the application of ankle brace, both with 30 and 60 kPa application pressures. Furthermore, it was found that single limb balance was significantly worse with closed eyes compared to open eyes. EMG measurements showed that the sequence of lower limb activation onset was not affected in any of the three ankle brace application conditions. The results of this study showed that the application of an ankle brace with two different skin-brace interface pressures had no effect on overall single limb balance and the sequence of lower limb muscle activation.</p> <p>Conclusion</p> <p>These findings suggest that peripheral joint receptors are either not adequately stimulated by the brace application and therefore are not able to alter the balance control strategy of the CNS, or that they play a less important role in the control of single limb balance. Further research is needed in this area with more dynamic and functional measurements, before the safe use of ankle bracing can be widely recommended.</p

High Resolution MEMS Accelerometers to Estimate VO2 and Compare Running Mechanics between Highly Trained Inter-Collegiate and Untrained Runners

BACKGROUND: The purposes of this study were to determine the validity and reliability of high resolution accelerometers (HRA) relative to VO(2) and speed, and compare putative differences in HRA signal between trained (T) and untrained (UT) runners during treadmill locomotion. METHODOLOGY: Runners performed 2 incremental VO(2max) trials while wearing HRA. RMS of high frequency signal from three axes (VT, ML, AP) and the Euclidean resultant (RES) were compared to VO(2) to determine validity and reliability. Additionally, axial rms relative to speed, and ratio of axial accelerations to RES were compared between T and UT to determine if differences in running mechanics could be identified between the two groups. PRINCIPAL FINDINGS: Regression of RES was strongly related to VO(2), but T was different than UT (r = 0.96 vs 0.92; p<.001) for walking and running. During walking, only the ratio of ML and AP to RES were different between groups. For running, nearly all acceleration parameters were lower for T than UT, the exception being ratio of VT to RES, which was higher in T than UT. All of these differences during running were despite higher VO(2), O(2) cost, and lower RER in T vs UT, which resulted in no significant difference in energy expenditure between groups. CONCLUSIONS/SIGNFICANCE: These results indicate that HRA can accurately and reliably estimate VO(2) during treadmill locomotion, but differences exist between T and UT that should be considered when estimating energy expenditure. Differences in running mechanics between T and UT were identified, yet the importance of these differences remains to be determined

Bacteria-Induced Uroplakin Signaling Mediates Bladder Response to Infection

Urinary tract infections are the second most common infectious disease in humans and are predominantly caused by uropathogenic E. coli (UPEC). A majority of UPEC isolates express the type 1 pilus adhesin, FimH, and cell culture and murine studies demonstrate that FimH is involved in invasion and apoptosis of urothelial cells. FimH initiates bladder pathology by binding to the uroplakin receptor complex, but the subsequent events mediating pathogenesis have not been fully characterized. We report a hitherto undiscovered signaling role for the UPIIIa protein, the only major uroplakin with a potential cytoplasmic signaling domain, in bacterial invasion and apoptosis. In response to FimH adhesin binding, the UPIIIa cytoplasmic tail undergoes phosphorylation on a specific threonine residue by casein kinase II, followed by an elevation of intracellular calcium. Pharmacological inhibition of these signaling events abrogates bacterial invasion and urothelial apoptosis in vitro and in vivo. Our studies suggest that bacteria-induced UPIIIa signaling is a critical mediator of bladder responses to insult by uropathogenic E. coli

The Influence of Knee and Ankle Bracing on Lower Extremity Kinematics During a Cutting Maneuver

PURPOSE: To determine the effect of four brace conditions on the lower extremity kinematics during a jogging cutting maneuver. METHODS: 18 subjects (9 male and 9 female, age = 22.8±2.0 yrs, ht = 174.7±7.6 cm, wt = 74.9±14.5 kg) participated in this study. Each subject performed 7–10 jogging cutting trials while wearing each of the four brace conditions; ankle brace only (AB), knee brace only (KB), ankle and knee brace together (ABKB) and no brace (NB). Hip and knee sagittal and frontal plane kinematics and ankle sagittal plane kinematics were assessed for each subject during each of the brace conditions. RESULTS: ANOVA (α = .05) revealed that sagittal plane ankle and hip ROM were not influenced by brace condition. Sagittal plane knee ROM was significantly reduced in the KB compared to the NB condition. Frontal plane knee ROM revealed a more varus position during the KB and ABKB conditions compared to the NB and AB conditions. The results also revealed that the hip was significantly more abducted during the KB and ABKB conditions when compared to the AB and NB conditions. CONCLUSIONS: The results indicate that the KB and the ABKB significantly influenced frontal plane hip and knee ROM and sagittal plane knee ROM during a jogging cutting maneuver. These braces may be beneficial in preventing excessive motion at the respective joint however it is important to consider their impact at the hip joint as a result of these bracing techniques. It is possible that these changes in ROM may result in subsequent changes in joint moments and or ground reaction forces

Economy of acceleration for individual axes versus speed in highly trained collegiate (Blue) and untrained (Green) runners during the run stages only.

<p>a) VT b) ML c) AP d) RES. Significant effects for speed in VT and RES (p<.001) and for training present in all axes (p<.001).</p