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1.
Biomedicines ; 12(3)2024 Mar 13.
Article in English | MEDLINE | ID: mdl-38540255

ABSTRACT

Therapeutic antibodies (Abs) which act on a broader range of epitopes may provide more durable protection against the genetic drift of a target, typical of viruses or tumors. When these Abs exist concurrently on the targeted antigen, several mechanisms of action (MoAs) can be engaged, boosting therapeutic potency. This study selected combinations of four and five Abs with non- or partially overlapping epitopes to the SARS-CoV-2 spike glycoprotein, on or outside the crucial receptor binding domain (RBD), to offer resilience to emerging variants and trigger multiple MoAs. The combinations were derived from a pool of unique-sequence scFv Ab fragments retrieved from two SARS-CoV-2-naïve human phage display libraries. Following recombinant expression to full-length human IgG1 candidates, a biolayer interferometric analysis mapped epitopes to bins and confirmed that up to four Abs from across the bins can exist simultaneously on the spike glycoprotein trimer. Not all the bins of Abs interfered with the spike protein binding to angiotensin converting enzyme 2 (ACE2) in competitive binding assays, nor neutralized the pseudovirus or authentic virus in vitro, but when combined in vivo, their inclusion resulted in a much stronger viral clearance in the lungs of intranasally challenged hamsters, compared to that of those treated with mono ACE2 blockers. In addition, the Ab mixtures activated in vitro reporter cells expressing Fc-gamma receptors (FcγRs) involved in antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADCP). The best four-Ab combination neutralized seventeen variants of concern from Wuhan-Hu1 to Omicron BA.4/BA.5 in vitro.

2.
Blood Cells Mol Dis ; 102: 102760, 2023 09.
Article in English | MEDLINE | ID: mdl-37267696

ABSTRACT

Hematopoiesis and lineage commitment are regulated by several conserved cell-intrinsic signaling pathways, including MAPKs and ß-catenin/TCF/LEF. The Inhibitor of MyoD Family A (I-MFA), a transcriptional repressor and tumor suppressor gene, interacts with these pathways and is dysregulated in chronic and acute myeloid leukemias, suggesting it may play a role in development and differentiation during hematopoiesis. To study this, immune cell populations in the bone marrow (BM) and periphery were analyzed in mice lacking Mdfi, encoding I-MFA (I-MFA-/-), and wild type (WT) controls. I-MFA-/- mice had reduced spleen and BM cellularity, with significant hyposplenism, compared to WT mice. In blood, total red blood cells and platelet counts were significantly reduced in I-MFA-/- mice, accompanied by a reduction in megakaryocyte (MK)/erythrocyte progenitor cells and an increase in myeloid progenitors in BM compared to WT mice. The K562 cell line exhibits PMA-induced MK differentiation, and shRNA knockdown of I-MFA resulted in reduced differentiation compared to control, with an increase and prolongation in phospho-JNK and phospho-ERK signaling. Overexpression of I-MFA promoted MK differentiation. These results suggest I-MFA plays a cell-intrinsic role in the response to differentiation signals, an effect that can be explored in the context of hematological cancers or other blood proliferative disorders.


Subject(s)
Bone Marrow , Megakaryocytes , Mice , Animals , Bone Marrow/metabolism , Cell Differentiation , Hematopoiesis , Bone Marrow Cells/pathology , Cell Lineage
3.
Circ Heart Fail ; 15(8): e009288, 2022 08.
Article in English | MEDLINE | ID: mdl-35862007

ABSTRACT

BACKGROUND: A systemic proinflammatory state plays a central role in the development of heart failure with preserved ejection fraction (HFpEF). Low-level transcutaneous vagus nerve stimulation (LLTS) suppresses inflammation in animals and humans, mediated by an α7nAchR (alpha7 nicotinic acetylcholine receptor)-dependent pathway. We examined the effects of LLTS on cardiac function, inflammation, and fibrosis in the presence of α7nAchR pharmacological blockade in a rat model of HFpEF. METHODS: Dahl salt-sensitive rats at 7 weeks of age were treated with high-salt diet for 6 weeks to induce HFpEF, followed by 4 weeks of (1) LLTS, (2) LLTS with the α7nAchR blocker methyllycaconitine, (3) sham, and (4) olmesartan. Blood pressure, cardiac function by echocardiography, heart rate variability, and serum cytokines were measured at 13 and 17 weeks of age. Cardiac fibrosis, inflammatory cell infiltration, and gene expression were determined at 17 weeks. RESULTS: LLTS attenuated the increase in blood pressure; improved cardiac function; decreased inflammatory cytokines, macrophage infiltration, and fibrosis; and improved survival compared with other groups. Methyllycaconitine attenuated these effects, whereas olmesartan did not improve cardiac function or fibrosis despite maintaining similar blood pressure as LLTS. Heart rate variability was similarly improved in the LLTS and LLTS plus methyllycaconitine groups but remained low in the other groups. LLTS reversed the dysregulated inflammatory signaling pathways in HFpEF hearts. CONCLUSIONS: Neuromodulation with LLTS improved cardiac function in a rat model of HFpEF through its anti-inflammatory and antifibrotic effects. These results provide the basis for further clinical trials in humans.


Subject(s)
Heart Failure , Vagus Nerve Stimulation , Animals , Anti-Inflammatory Agents/therapeutic use , Cytokines/metabolism , Fibrosis , Heart Failure/drug therapy , Humans , Infant , Inflammation/drug therapy , Phenotype , Rats , Rats, Inbred Dahl , Stroke Volume/physiology , alpha7 Nicotinic Acetylcholine Receptor/therapeutic use
4.
Cureus ; 14(12): e32260, 2022 Dec.
Article in English | MEDLINE | ID: mdl-36620853

ABSTRACT

Knowledge of right hepatic artery (RHA) and cystic artery (CA) variations is crucial for surgeons performing procedures on the hepatobiliary system, pancreas, and duodenum. Commonly, the RHA originates from the superior mesenteric artery (SMA), while the CA originates from the RHA and is found within the cystic triangle during laparoscopic cholecystectomies. Here we investigated variations in the origin and path of the RHA and CA in a sample of American midwestern cadavers (n = 18) from the Gift of Body Program at A.T. Still University's Kirksville College of Osteopathic Medicine. Portal triads and associated vessels were dissected to reveal the artery pathways. The origin, branching pattern, and course of the RHA and CA were documented, and descriptive measurements were taken. We describe four cases where the RHA originated from the anterolateral proximal SMA, traveled deep to the pancreatic neck, and had a slightly variable but close relationship with the portal triad structures. The CA was present in the cystic triangle in all 18 donors, typically originating from the RHA except for one case where it originated from the left hepatic artery. In six cases, the CA originated outside of the cystic triangle, crossing either superficially or deeply to the common hepatic duct to enter the cystic triangle. Knowledge of these variations will enhance preoperative planning and the overall safety of surgical procedures in this area.

5.
Exp Physiol ; 106(3): 673-682, 2021 03.
Article in English | MEDLINE | ID: mdl-33428276

ABSTRACT

NEW FINDINGS: What is the central question of this study? Prior studies failed to address the role of sex in modifying the pathophysiology and response to therapy in heart failure with preserved ejection fraction (HFpEF), potentially introducing bias into translational findings. We aimed to explore sex differences in outcomes and sought to identify the underlying mechanisms in a well-established rat model of HFpEF. What is the main finding and its importance? Male rats with HFpEF exhibited worse survival compared with females and were at a higher risk for sudden death, attributable in part to QT prolongation, autonomic dysregulation and enhanced inflammation. These data might provide the basis for the development of sex-specific interventions in HFpEF targeting these abnormalities. ABSTRACT: Heart failure with preserved ejection fraction (HFpEF) accounts for 50% of heart failure, and sudden death is the leading cause of mortality. We aimed to explore sex differences in outcomes in rats with HFpEF and sought to identify the underlying mechanisms. Dahl salt-sensitive rats of either sex were randomized into high-salt diet (HS diet; 8% NaCl, n = 46, 50% female) or low-salt diet (LS diet; 0.3% NaCl; n = 24, 50% female) at 7 weeks of age. After 6 and 10 weeks of LS or HS diets, the ECG, heart rate variability, cytokines and echocardiographic parameters were measured. The animals were monitored daily for development of HFpEF and survival. Over 6 weeks of HS diet, rats developed significant hypertension and signs of HFpEF. Compared with female HS diet-fed rats, males exhibited more left ventricular dilatation, a longer QT interval, and worse autonomic tone, as assessed by heart rate variability and elevated inflammatory cytokines. Ten of 23 (46%) male rats died during follow-up, compared with two of 23 (9%) female rats (P = 0.01). There were four sudden deaths in males (with ventricular tachycardia documented in one rat), whereas the females died of heart failure. In conclusion, male rats with HFpEF exhibit worse survival compared with females and are at a higher risk for sudden death, attributable in part to QT prolongation, autonomic dysregulation and enhanced inflammation. These data might provide the basis for the development of sex-specific interventions in HFpEF targeting these abnormalities.


Subject(s)
Heart Failure , Animals , Female , Incidence , Male , Rats , Rats, Inbred Dahl , Sex Characteristics , Stroke Volume/physiology , Ventricular Function, Left/physiology
6.
Cureus ; 13(12): e20854, 2021 Dec.
Article in English | MEDLINE | ID: mdl-35111489

ABSTRACT

Erythema multiforme major (EMM) is a rare type IV cytotoxic reaction targeting keratinocytes of the mucosal surfaces and the dermis. Dusky, targetoid lesions with central clearing are classically present, which may become blistered and rupture. The disease is usually self-limited and managed with supportive care and treatment of the underlying condition. The most common triggering factors are adverse reactions to medications, herpes simplex virus (HSV), and Mycoplasma pneumoniae. Rapid recognition of EMM is essential to avoid long-term complications. This case presents a 39-year-old male with a unique history of recent non-steroidal anti-inflammatory drug (NSAID) use, past infection with HSV-1, and an acute Mycoplasma pneumoniae infection. The patient developed painful lesions on the skin, oral mucosa, ocular surfaces, and urethra. The painful lesions caused complications with feeding and voiding. Initially, the triggering event was unclear. Supportive care was started. NSAIDs were discontinued and similarly-structured drugs were avoided. Treatments targeting Mycoplasma pneumoniae and HSV-1 were initiated while lab results were pending. Once the results returned, the treatment regimen of corticosteroids for inflammation, acyclovir for HSV-1, and azithromycin for Mycoplasma pneumoniae was continued. Vaseline was applied to open lesions. The patient was also treated with mouthwash consisting of aluminum (Al) hydroxide/magnesium (Mg) hydroxide/simethicone (400 mg/400 mg/40 mg). Topical 2% lidocaine gel with applicator was used to assist with urinary discomfort during voiding. Fentanyl was used for pain control. The patient successfully recovered and was discharged to follow-up with ophthalmology. Long-term sequelae including trichiasis, symblepharon, and punctal stenosis were noted during follow-up appointments.

7.
Mo Med ; 117(5): 461-468, 2020.
Article in English | MEDLINE | ID: mdl-33311756

ABSTRACT

This study evaluated soft-embalmed human cadavers for ultrasound needle-guidance training. Second-year medical students used peripherally inserted central catheter (PICC) line and central line models and a Thiel-embalmed cadaver for training and provided feedback. Most (85%) agreed the cadaver was useful. There were positive correlations between performing the PICC line (r=0.44, P=.11) and central line (r=0.63, P=.03) procedures on a cadaver and in a clinical setting. Thiel-embalmed cadavers may provide important hands-on training.


Subject(s)
Embalming , Students, Medical , Cadaver , Humans , Ultrasonography
8.
J Orthop Sports Phys Ther ; 50(5): 276, 2020 May.
Article in English | MEDLINE | ID: mdl-32354315

ABSTRACT

A 21-year-old male Army basic trainee was evaluated in a direct-access physical therapy clinic for left-sided low back pain. Following examination, radiographs and a bone scan were ordered. The findings prompted referral for a computed tomography scan of the pelvis, which characterized an infiltrative soft tissue mass. The therapist immediately contacted an orthopaedic surgeon, who recommended that the physical therapist order immediate magnetic resonance imaging (STAT MRI). The patient underwent a tissue biopsy and subsequently was diagnosed with Ewing's sarcoma. J Orthop Sports Phys Ther 2020;50(5):276. doi:10.2519/jospt.2020.9109.


Subject(s)
Accidental Falls , Bone Neoplasms/diagnostic imaging , Ilium/diagnostic imaging , Military Personnel , Sarcoma, Ewing/diagnostic imaging , Biopsy , Humans , Low Back Pain/etiology , Magnetic Resonance Imaging , Male , Radionuclide Imaging , Tomography, X-Ray Computed , Young Adult
9.
Mo Med ; 115(1): 61-65, 2018.
Article in English | MEDLINE | ID: mdl-30228685

ABSTRACT

The current study surveyed first-year osteopathic medical students about dissection, multimedia dissector, split laboratories, VH (virtual human) dissector, ultrasonography, and prior experience of anatomical concepts. Students perceived cadaveric dissection, multimedia dissector, and ultrasonography laboratories as important contributors for learning anatomy. Students felt cadaveric dissection was an important factor in their medical school selection. Study results suggested students perceived integrated anatomy courses that utilized dissection and multimodal approaches to deliver anatomical information as highly effective.


Subject(s)
Anatomy/education , Dissection/education , Education, Medical, Undergraduate/methods , Osteopathic Medicine/education , Students, Medical/psychology , Adult , Cadaver , Dissection/methods , Female , Humans , Male , Multimedia , Surveys and Questionnaires , Ultrasonography , Virtual Reality
10.
Mil Med ; 182(11): e2095-e2098, 2017 11.
Article in English | MEDLINE | ID: mdl-29087889

ABSTRACT

Stress fractures of the femoral neck are career-threatening and life-altering injuries that occur frequently in Initial Entry Training (IET) Soldiers. Because of the severity of these injuries, military clinics that serve IET Soldiers have implemented guidelines to direct providers in the management of Soldiers with signs of symptoms of stress fracture. These guidelines focus on Soldiers presenting with a primary complaint of hip pain. The cases described here show two Soldiers who had displaced hip fractures despite having primary complaints of knee pain and no self-reported hip pain. In the first case, the patient was ambulatory with a slight limp and lateral knee pain that he rated as 3 out of 10. His physical therapist noted a significant gross leg length discrepancy on physical examination. Leg length X-rays identified a displaced fracture of the femoral neck. In the second case, the Soldier had severe (7/10) lateral knee pain with no complaints of hip pain. He presented to the Emergency Department where he received knee X-rays, which were normal. The next day in physical therapy, he continued to complain of severe knee pain. A femur X-ray demonstrated that he had a displaced hip fracture. Throughout their examination and diagnostic workup, neither of these patients ever experienced any hip pain. The implication of these cases is that clinicians must remain vigilant in examining the joints above and below the primary complaint. This may be more important when evaluating trainees who have a uniquely high risk of severe bone stress injury. Clinicians who work primarily with trainees should consider updating clinical management guidelines to include basic hip screening on patients who present with primary complaints of knee pain. Because of cases like these and the known connection between knee pain and hip pathology, we recommend that clinicians in IET clinics consider screening procedures to rule out hip pathology in trainees with primary complaints of knee pain.


Subject(s)
Fractures, Stress/complications , Hip Dislocation/therapy , Military Personnel , Adult , Education/trends , Femoral Neck Fractures/complications , Fractures, Stress/therapy , Hip Dislocation/complications , Hip Dislocation/diagnostic imaging , Humans , Male , Pain/etiology , Pain Management , Physical Therapy Department, Hospital/organization & administration , Physical Therapy Modalities/organization & administration , Radiography/methods
11.
J Strength Cond Res ; 24(10): 2613-7, 2010 Oct.
Article in English | MEDLINE | ID: mdl-20844455

ABSTRACT

The purpose of this study was to determine the difference in 40-yd dash and proagility times performed on field turf (FT) and natural grass (NG). Red-shirt freshmen National Collegiate Athletic Association Division II college football players (n = 24) performed 2 trials each of a 40-yd dash and proagility run on each surface. Sprints were timed by an electronic timing system (ET) and by 2 hand timers (HTs). Agility was timed on each surface by 2 HTs. There was no significant difference in 40-yd dash times between FT and NG using ET (FT: 5.34 ± 0.30 seconds, NG: 5.33 ± 0.33 seconds) or HT (FT: 5.06 ± 0.31 seconds, NG: 5.11 ± 0.29 seconds). Hand timer 40-yd dashes were significantly faster than ET 40-yd dashes on both surfaces, with the difference between HT and ET on FT (-0.28 ± 0.11 seconds) significantly greater than the difference on NG (-0.22 ± 0.06 seconds). The time differences between surfaces were significantly correlated (r = 0.12, p = 0.56). Proagility times were significantly faster on FT (4.49 ± 0.28 seconds) than on grass (4.64 ± 0.33 seconds). Thus, it appears that straight-ahead sprint speed is similar between FT and NG, but change-of-direction speed may be significantly faster on FT.


Subject(s)
Athletes , Athletic Performance , Football , Poaceae , Running , Time and Motion Studies , Adolescent , Humans , Surface Properties , Universities , Young Adult
12.
J Strength Cond Res ; 24(2): 447-51, 2010 Feb.
Article in English | MEDLINE | ID: mdl-20072055

ABSTRACT

The purpose of this study was to determine the difference between hand and electronic timing of 40-yd dashes in college football players. National Collegiate Athletic Association Division II players (n = 59) were measured during a 40-yd sprint by electronic timing and simultaneously by 7 experienced hand timers using digital stopwatches. Electronic times were initiated by lifting the hand from a switch mat and stopped by the torso passing through an infrared beam. Hand timers initiated timing on first movement of the player from a 3-point stance. To establish performance and timing reliabilities, 32 players completed a second trial. Interrater reliability for hand timing was intraclass correlation coefficient (ICC) = 0.987 (p < 0.001). Five of the 7 timers did not differ significantly (p > 0.05) in their timing. The maximum difference among the hand timers on any given trial was 0.19 +/- 0.14 seconds, with a 95% confidence interval (CI) of -0.08 to 0.41 seconds. Hand timing (4.85 +/- 0.28 seconds) was significantly faster (p < 0.001) than electronic timing (5.16 +/- 0.28 seconds), producing an average difference of 0.31 +/- 0.07 seconds (6.0 +/- 1.3%) and a 95% CI on the average difference of -0.44 to -0.18 seconds. The correlation between electronic timing and hand timing was ICC = 0.985 (p < 0.001). Practically speaking, electronic timing produces the best measurement of 40-yd dash speed, and using the hand timing produces consistently but significantly faster times.


Subject(s)
Football/physiology , Running/physiology , Time , Analysis of Variance , Electrical Equipment and Supplies , Humans , Male , Reproducibility of Results , Sports Equipment , Young Adult
13.
Appl Ergon ; 40(5): 895-903, 2009 Sep.
Article in English | MEDLINE | ID: mdl-19187929

ABSTRACT

This study aims to investigate the effects of shoe traction and obstacle height on lower extremity relative phase dynamics (analysis of intralimb coordination) during walking to better understand the mechanisms employed to avoid slippage following obstacle clearance. Ten participants walked at a self-selected pace during eight conditions: four obstacle heights (0%, 10%, 20%, and 40% of limb length) while wearing two pairs of shoes (low and high traction). A coordination analysis was used and phasing relationships between lower extremity segments were examined. The results demonstrated that significant behavioral changes were elicited under varied obstacle heights and frictional conditions. Both decreasing shoe traction and increasing obstacle height resulted in a more in-phase relationship between the interacting lower limb segments. The higher the obstacle and the lower the shoe traction, the more unstable the system became. These changes in phasing relationship and variability are indicators of alterations in coordinative behavior, which if pushed further may have lead to falling.


Subject(s)
Friction , Lower Extremity , Motor Skills , Shoes , Traction , Walking , Adolescent , Adult , Ergonomics , Humans , Male , Nebraska , Nonlinear Dynamics , Young Adult
14.
Ergonomics ; 51(12): 1847-59, 2008 Dec.
Article in English | MEDLINE | ID: mdl-18608479

ABSTRACT

This study aims to investigate the effects of shoe traction and obstacle height on friction during walking to better understand the mechanisms required to avoid slippage following obstacle clearance. Ten male subjects walked at a self-selected pace during eight different conditions: four obstacle heights (0%, 10%, 20% and 40% of limb length) while wearing two different pairs of shoes (low and high traction). Frictional forces were calculated from the ground reaction forces following obstacle clearance, which were sampled with a Kistler platform at 960 Hz. All frictional peaks increased with increases in obstacle height. Low traction shoes yielded smaller peaks than high traction shoes. The transition from braking to propulsion occurred sooner due to altered control strategies with increased obstacle height. Collectively, these results provided insights into kinetic strategies of leading limb when confronted with low traction and high obstacle environments. This study provides valuable information into the adaptations used to reduce the potential of slips/falls when confronted with environments characterised by low shoe-floor friction and obstacles. It also provides the necessary foundation to explore the combined effects of shoe traction and obstacle clearance in elderly people, more sensitive to slippage.


Subject(s)
Friction , Gait/physiology , Shoes , Adult , Biomechanical Phenomena , Humans , Male , Range of Motion, Articular , Young Adult
15.
J Strength Cond Res ; 21(2): 385-8, 2007 May.
Article in English | MEDLINE | ID: mdl-17530959

ABSTRACT

The objective of this study was to determine performance differences between individual and competitive trials of the 40-yard dash. Physically active college men (n = 25) and women (n = 29) performed an individual 40-yard dash, followed by completion of the Sports Competition Trait Inventory (SCTI) before performing a paired 40-yard dash against a time-matched competitor. All sprints were performed on an indoor rubberized track using photoelectric gates to start and stop a digital timer. In addition, 3 timers used hand-held stopwatches to record the individual sprint time. There was no significant difference (p = 0.10) between men (120.3 +/- 16.6) and women (111.7 +/- 20.3) on the SCTI. There was no significant difference between individual and competitive 40-yard dash times for either men (5.21 +/- 0.24 and 5.19 +/- 0.23 seconds, respectively) or women (6.12 +/- 0.31 and 6.11 +/- 0.32 seconds, respectively). The correlation between SCTI and both individual and competitive 40-yard dashes was significant (p < 0.05) for women (r = -0.45 and -0.44, respectively) but not for men (r = -0.10 and 0.10, respectively). Electronic times (5.70 +/- 0.54 seconds) were not significantly different from 1 hand-timer (5.71 +/- 0.56 seconds) but were significantly faster than the other 2 timers (5.80 +/- 0.58 and 5.82 +/- 0.57 seconds). Averaging the 3 hand times (5.78 +/- 0.56 seconds) for comparison with the electronic timing (5.70 +/- 0.54 seconds) produced a high correlation (r = 0.96) but a significantly slower time (p < 0.05). A competitive environment does not appear to improve short sprint times in either men or women. In addition, hand timing may not always produce faster times compared to electronic timing.


Subject(s)
Competitive Behavior , Running/physiology , Adult , Analysis of Variance , Female , Humans , Male , Sex Factors
16.
Neurosci Lett ; 334(2): 75-8, 2002 Dec 13.
Article in English | MEDLINE | ID: mdl-12435475

ABSTRACT

The purpose of this investigation was to determine if the location and the timing relative to muscle activation onset, of a mechanical stimulus applied to the soles impacted the neuromuscular activation associated with a voluntary movement. The subjects completed a series of dorsiflexion or plantarflexion movements during which a stimulus was applied to either the heel or ball of the foot at one of three time periods relative to the initiation of the agonist muscle. Surface electromyography from the tibialis anterior and soleus was collected during the movements. The results show that if the stimulus was applied shortly before agonist muscle activation, regardless of stimulation site, the neuromuscular activity associated with the movement was greatly increased.


Subject(s)
Foot/physiology , Muscle Contraction/physiology , Muscle, Skeletal/physiology , Physical Stimulation , Adult , Ankle/physiology , Electromyography , Female , Foot/innervation , Humans , Male , Movement/physiology , Pressure
17.
Percept Mot Skills ; 94(1): 265-80, 2002 Feb.
Article in English | MEDLINE | ID: mdl-11883574

ABSTRACT

This study investigated intralimb coordination during walking in young and elderly women using the theoretical model of dynamical systems. 20 women, 10 Young (M age=24.6 yr., SD= 3.2 yr.) and 10 Elderly (M age=73.7 yr., SD=4.9 yr.), were videotaped during free speed gait and gait perturbed by an ankle weight. Two parameters, one describing the phasing relationship between segments (mean absolute relative phase) and the other the variability of this relationship (deviation in phase), were calculated from the kinematics. Two-way analysis of variance (age and weight) with repeated measures on weight indicated that during the braking period the weight increased the mean absolute relative phase between the shank and the thigh and decreased it between the foot and the shank. The Elderly women had significant smaller values for the mean absolute relative phase between the shank and the thigh during the braking period. For the same period, deviation in phase increased for the segmental 'relationship between the shank and the thigh. The findings suggest that changes in intralimb coordination take place with asymmetrical weighting and the aging process. These changes are most clearly present during the braking period.


Subject(s)
Gait , Movement/physiology , Adult , Age Factors , Aged , Aging/physiology , Body Mass Index , Humans , Muscle, Skeletal/physiology
18.
Med Sci Sports Exerc ; 34(1): 123-9, 2002 Jan.
Article in English | MEDLINE | ID: mdl-11782657

ABSTRACT

PURPOSE: Running over obstacles of sufficient height requires heel strike (HS) runners to make a transition in landing strategy to a forefoot (FF) strike, resulting in similar ground reaction force patterns to those observed while landing from a jump. Identification of the biomechanical variables that distinguish between the landing strategies may offer some insight into the reasons that the transition occurs. The purpose of this study was to investigate the difference in foot strike patterns and kinetic parameters of heel strike runners between level running and running over obstacles of various heights. METHODS: Ten heel strike subjects ran at their self-selected pace under seven different conditions: unperturbed running (no obstacle) and over obstacles of six different heights (10%, 12.5%, 15%, 17.5%, 20%, and 22.5% of their standing height). The obstacle was placed directly before a Kistler force platform. Repeated measures ANOVAs were performed on the subject means of selected kinetic parameters. RESULTS: The statistical analysis revealed significant differences (P < 0.004) for all of the parameters analyzed. The evaluation of the center of pressure and the ground reaction forces indicated that the foot strike patterns were affected by the increased obstacle height. Between the 12.5% and 15% obstacle conditions, the group response changed from a heel strike to a forefoot strike pattern. CONCLUSIONS: At height > 15%, the pattern was more closely related to the foot strike patterns found in jumping activities. This strategy change may represent a gait transition effected as a mechanism to protect against increased impact forces. Greater involvement of the ankle and the calf muscles could have assisted in attenuating the increased impact forces while maintaining speed after clearing the obstacle.


Subject(s)
Foot/physiology , Gait/physiology , Motor Activity/physiology , Running/physiology , Adult , Female , Heel/physiology , Humans , Kinetics , Male , Pressure , Stress, Mechanical
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