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1.
Res Q Exerc Sport ; : 1-10, 2024 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-38842825

RESUMO

Background: Physical literacy and injury prevention strategies use similar movement-related constructs and can be connected to develop comprehensive interventions. We aimed to test the feasibility and effects of a neuromuscular warm-up based on physical literacy and injury prevention strategies for 8-12-year-old children. Methods: We conducted a cluster non-randomized controlled trial. We defined a priori feasibility criteria and studied the effects of the intervention on physical literacy constructs, movement competence, and neuromuscular performance. We used generalized linear mixed models controlling for covariates and clustering with a significance level of 0.001. Results: We recruited 18 groups (n = 363) and randomly allocated nine to intervention (n = 179; female = 63.7%, age = 9.8 ± 1 years) and nine to control (n = 184, female = 53.3%, age = 9.9 ± 0.9 years). We met four of seven feasibility criteria (i.e. recruitment, adherence, enjoyment, perceived exertion). The three feasibility criteria that were not met (i.e. compliance, fidelity, follow-up) were slightly below the predefined threshold (90%). Model-adjusted mean differences for physical literacy constructs, movement competence, vertical jump height, horizontal jump distance, 20-m sprint time, and dynamic balance favored the intervention (p < .001). Conclusion: The feasibility evidence indicates that the intervention should be slightly modified before implementing it in a larger study. The observed mean differences are promising and can be used in planning future interventions.

2.
J Clin Med ; 12(18)2023 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-37762861

RESUMO

Low back pain (LBP), a globally widespread and persistent musculoskeletal disorder, benefits from exercise therapy. However, it remains unclear which type leads to greater changes in paraspinal muscle health. This study aimed to (1) compare the effects of a combined motor control and isolated lumbar extension exercise (MC+ILEX) versus a general exercise (GE) intervention on paraspinal muscle morphology, composition, and function, and (2) examine whether alterations in paraspinal muscle health were correlated with improvements in pain, function, and quality of life. Fifty participants with chronic LBP were randomly assigned to each group and underwent a 12-week supervised intervention program. Magnetic resonance imaging and ultrasound assessments were acquired at baseline, 6 and 12 weeks to examine the impact of each intervention on erector spinae (ES) and multifidus (MF) muscle size (cross-sectional area, CSA), composition, and function at L4-L5 and L5-S1. Self-reported questionnaires were also acquired to assess participant-oriented outcomes. Our findings indicated that the MC+ILEX group demonstrated greater improvements in MF and ES CSA, along with MF thickness at both levels (all p < 0.01). Both groups significantly improved in pain, function, and quality of life. This study provided preliminary results suggesting that an MC+ILEX intervention may improve paraspinal morphology while decreasing pain and disability.

3.
Am J Health Promot ; 37(5): 705-719, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-36527377

RESUMO

OBJECTIVE: Fundamental movement skills (FMS) are essential to participate in physical activity. Understanding the effects of multicomponent injury prevention programs (MIPP) on FMS may help promote safe physical activity. Our objective was to synthesize the evidence on the effects of MIPP on biomechanical outcomes and neuromuscular performance measured on children and adolescents while performing FMS. DATA SOURCE: We searched PubMed, SPORTDiscus, Web of Science, and SCOPUS. STUDY INCLUSION AND EXCLUSION CRITERIA: We included peer-reviewed randomized controlled trials, published in English, that analyzed the effects of MIPP on biomechanics and neuromuscular performance of FMS in participants under 18 years of age. DATA EXTRACTION: Two reviewers screened the articles, assessed the quality of the evidence using the Physiotherapy Evidence Database (PEDro) scale, and synthesized the data. DATA SYNTHESIS: We conducted meta-analyses and reported the characteristics, outcomes, and risk of bias of studies. RESULTS: We included 27 articles that reported data from 1,427 participants. Positive effects on FMS were reported in 23 of the 27 included articles. Vertical Jump, running speed, acceleration, and dynamic balance presented positive-significant pooled effect sizes. Dribbling and horizontal jump presented non-significant pooled effect sizes. CONCLUSION: MIPP can positively affect FMS in children and adolescents in sports-related settings. Lack of participant compliance and implementation fidelity may affect MIPP effectiveness. Including MIPP in physical literacy interventions, physical education classes, and organized physical activity may lead to functional adaptations that help promote safe physical activity.


Assuntos
Exercício Físico , Corrida , Criança , Humanos , Adolescente
4.
J Athl Train ; 57(4): 360-370, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35439310

RESUMO

CONTEXT: Patient-reported outcome measures (PROMs) should be used in athletic training and athletic therapy but are rarely incorporated in internships. Student-run clinics are common in other health professions and provide effective treatment and valuable learning environments. To our knowledge, no one has evaluated rehabilitation outcomes in patients treated by athletic therapy students (ATSs). OBJECTIVE: To measure the improvement in function in injured patients seeking treatment at an ATS clinic. DESIGN: Cohort study. SETTING: An ATS clinic. PATIENTS OR OTHER PARTICIPANTS: A total of 59 patients (32 women, age = 33.9 ± 14.7 years; 27 men, age = 38 ± 14.4 years) from the community with a variety of low back, lower extremity, and upper extremity injuries participated. MAIN OUTCOME MEASURE(S): At baseline and 6-week follow-up, all patients completed 1 of 3 scales (depending on their injury location) to assess their injured level of function. Scales were the Oswestry Disability Index for low back injuries; Lower Extremity Functional Scale for lower extremity injuries; and Disabilities of the Arm, Shoulder and Hand for upper extremity injuries. RESULTS: On average, patients received 4.7 ± 1.8 treatments across 48.8 ± 16.1 days. They experienced an increase in function between baseline and follow-up assessments (18.8% ± 20.3%; P < .001, Cohen d = 1.06). Moreover, the amount of functional improvement was clinically meaningful, as it was greater than the minimal clinically important difference for each scale. The efficacy of treatments did not differ according to the internship experiences of the ATSs. CONCLUSIONS: Function improved in patients after treatment delivered by an ATS. Patient-reported outcome measures were useful for the students in monitoring patient improvement, but more research is needed regarding effective treatments for patients with chronic pain. Our results suggested that ATS clinics provide effective treatments for patients, service to the community, and a learning opportunity for students.


Assuntos
Traumatismos em Atletas , Esportes , Adulto , Traumatismos em Atletas/reabilitação , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Medidas de Resultados Relatados pelo Paciente , Estudantes , Adulto Jovem
5.
J Sport Rehabil ; 31(2): 224-229, 2022 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-34525450

RESUMO

Clinical Scenario: Injury prevention programs are becoming standard practice for reducing sports-related injuries, but most programs focus on musculoskeletal elements. Psychological factors can be strong predictors of sports-related injuries and there is recent evidence that suggests psychological interventions can be effective at reducing injury risk. It is unclear if injury prevention programs that focus on psychological factors are an important inclusion for athletic trainers/therapists. Athletes can be exposed to different psychological factors based on sport type including team or individual sports, which can increase their risk of injury. While psychological interventions can reduce injuries by addressing psychological symptoms, it is unclear if the interventions are effective for at-risk athletes in addition to athletes who are not suffering from any psychological factors. Currently, there are no guidelines or recommendations for athletic trainers/therapists to address psychological factors with the purpose of injury prevention. Clinical Question: Are psychological intervention programs effective in reducing sports-related injury risk and are they clinically relevant to athletic trainers/therapists for implementation in all settings? Summary of Findings: The authors searched the literature for studies investigating the use of psychological intervention programs to reduce sports-related injuries in an athletic population. The search returned 6 possible papers (2 systematic reviews without meta-analysis, 1 systematic review with a meta-analysis, 2 meta-analyses, and 1 randomized control trial not included in the systematic reviews). The authors narrowed our appraisal to one systematic review and one randomized controlled trial. The review contained all the studies from the previous review papers including 3 studies which performed screening procedures. The collection of evidence demonstrates positive effects associated with implementing psychological intervention techniques to reduce sports injury rates in all athletes; at-risk athletes, not at-risk athletes, and individual and team-sport athletes. Bottom Line: There is sufficient evidence supporting the use of a psychological-based intervention by athletic trainers/therapists to effectively reduce the number of injury occurrences in the athletic population. Direct comparisons of effectiveness between team and individual sports was not conducted in the research, but a substantial representation of both sport types existed. The current evidence includes a variety of athletic populations, at-risk and not at-risk, different sport types, and competition levels. Athletic trainers/therapists should consider the integration of psychological disciplines in current injury prevention practices to address the psychological concerns which put athletes at additional risk for injury. Strength of Recommendation: Grade B evidence exists to support the use of psychological intervention strategies in a well-developed injury prevention plan. Sports medicine practitioners can help athletes reduce stress, increase mindfulness, and be more aware of mental health practices which helps reduce injury risk.


Assuntos
Traumatismos em Atletas , Medicina Esportiva , Esportes , Atletas , Traumatismos em Atletas/prevenção & controle , Humanos , Intervenção Psicossocial
6.
BMC Musculoskelet Disord ; 22(1): 472, 2021 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-34022854

RESUMO

BACKGROUND: Exercise is a common approach for the management of patients with chronic non-specific low back pain (LBP). However, there is no clear mechanistic evidence or consensus on what type of exercise is more effective than others. While considerable evidence suggests a link between lumbar muscle health (e.g., atrophy and fatty infiltration) with functional deficits, it is unknown whether exercises targeting the lumbar spine can lead to noticeable improvements in muscle health and functional outcomes. The primary aim of this study is to compare the effect of combined motor control and isolated strengthening lumbar exercises (MC + ILEX) versus a general exercise group (GE) on multifidus muscle morphology (size and composition). Secondary aims include assessing the effect of the interventions on overall paraspinal muscle health, pain and disability, as well as psychological factors as possible effect modifiers. METHODS: A total of 50 participants with chronic non-specific LBP and moderate to severe disability, aged between 18 and 60, will be recruited from the local orthopaedic clinics and university community. Participants will be randomised (1:1) to either the MC + ILEX or GE group. Participants will undergo 24 individually supervised exercise sessions over a 12-week period. The primary outcome will be multifidus morphology (atrophy) and composition (fatty infiltration). Secondary outcomes will be muscle function (e.g., % thickness change during contraction), morphology, lumbar extension strength, pain intensity and disability. Potential treatment effect modifiers including maladaptive cognitions (fear of movement, catastrophizing), anxiety, depression, physical activity, and sleep quality will also be assessed. All measurements will be obtained at baseline, 6-week and 12-week; self-reported outcomes will also be collected at 24-week. Between-subjects repeated measure analysis of variance will be used to examine the changes in paraspinal muscle morphology over the different time points. Linear mixed models will be used to assess whether baseline scores can modify the response to the exercise therapy treatment. DISCUSSION: The results of this study will help clarify which of these two common interventions promote better results in terms of overall paraspinal muscle heath, back pain, disability and psychological factors in adults with chronic LBP. TRIAL REGISTRATION: NTCT04257253 , registered prospectively on February 5, 2020.


Assuntos
Dor Lombar , Músculos Paraespinais , Adolescente , Adulto , Exercício Físico , Terapia por Exercício , Humanos , Dor Lombar/diagnóstico , Dor Lombar/terapia , Pessoa de Meia-Idade , Músculos Paraespinais/diagnóstico por imagem , Modalidades de Fisioterapia , Ensaios Clínicos Controlados Aleatórios como Assunto , Adulto Jovem
7.
J Altern Complement Med ; 27(3): 263-272, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33395535

RESUMO

Background: The World Health Organization benchmarks for osteopathic training consider cranial osteopathy as an important manual skill. Studies of cranial manual therapy have exhibited poor reliability. The aim of this study was to investigate the inter-rater reliability of the manual mobility tests of the spheno-occipital synchondrosis (SOS), and the temporal, parietal, and frontal bones, as assessed in osteopathic manual therapy. Methods: Twenty-one adults were assessed on a single day by three experienced osteopaths using a standard assessment protocol. Before data collection, the osteopaths participated in a consensus training, which included establishing the criteria for identifying a cranial bone mobility restriction; the application of the seven-step palpation method; a pretesting practice; a fine-tuning palpation training; and a calibration period before the assessment of the subjects. Three subjects were assessed simultaneously with the evaluators rotating to assess each subject. The evaluators were blinded to the subject by a curtain, and each other's assessments. Each bone was rated as restricted or not restricted. The authors applied the Landis and Koch classification to describe the magnitude of inter-rater reliability. Results: Moderate reliability was established for a lateral strain of the SOS (Fleiss' generalized kappa 0.48), substantial reliability was established for the other SOS strain patterns (Fleiss' generalized kappa 0.62-0.75), and almost perfect reliability for temporal, parietal, and frontal bone (Fleiss' generalized kappa 0.81-0.96). Conclusion: The results demonstrate consistency when three experienced osteopaths evaluate cranial bone mobility restrictions. The results highlight the importance of consensus training and rigorous methodology in manual therapy reliability studies.


Assuntos
Cabeça/fisiologia , Articulações/fisiologia , Osteopatia/métodos , Osteopatia/normas , Crânio/fisiologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Palpação , Reprodutibilidade dos Testes , Adulto Jovem
8.
Hum Mov Sci ; 70: 102596, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32217214

RESUMO

The purpose of this study was to investigate weight-bearing knee joint kinematic and neuromuscular responses during lateral, posterior, rotational, and combination (simultaneous lateral, posterior, and rotational motions) perturbations and post-perturbations phases in 30° flexed-knee and straight-knee conditions. Thirteen healthy female athletes participated. Knee joint angles and muscle activity of vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), semitendinosus (ST), lateral gastrocnemius (LG), and medial gastrocnemius (MD) muscles were computed. Knee abducted during lateral perturbations, whereas it adducted during the other perturbations. It was internally rotated during flexed-knee and externally rotated during straight-knee perturbations and post-perturbations. VL and VM's mean and maximum activities during flexed-knee perturbations were greater than those of straight-knee condition. BF's mean activities were greater during flexed-knee perturbations compared with straight-knee condition, while its maximum activities observed during combination perturbations. ST's maximum activities during combination perturbations were greatest compared with the other perturbations. LG and MG's activities were greater during straight-knee conditions. Compared with the perturbation phase, the mean and maximum muscles' activities were significantly greater during post-perturbations. The time of onset of maximum muscle activity showed a distinctive pattern among the perturbations and phases. The perturbation direction is an important variable which induces individualized knee kinematic and neuromuscular response.


Assuntos
Atletas , Articulação do Joelho/fisiologia , Adolescente , Basquetebol/fisiologia , Fenômenos Biomecânicos/fisiologia , Eletromiografia , Feminino , Humanos , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Amplitude de Movimento Articular , Rotação , Futebol/fisiologia , Adulto Jovem
9.
Gen Dent ; 62(3): 34-8, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24784512

RESUMO

There is continued speculation on the value of mouthguards (MGs) in preventing mild traumatic brain injury (MTBI)/concussion injuries. The purpose of this randomized prospective study was to compare the impact of pressure-laminated (LM), custom-made, properly fitted MGs to over-the-counter (OTC) MGs on the MTBI/concussion incidence in high school football athletes over a season of play. Four hundred twelve players from 6 high school football teams were included in the study. Twenty-four MTBI/concussion injuries (5.8%) were recorded. When examining the MTBI/concussion injury rate by MG type, there was a significant difference (P = 0.0423) with incidence rates of 3.6% and 8.3% in the LM MG and OTC MG groups, respectively.


Assuntos
Concussão Encefálica/prevenção & controle , Lesões Encefálicas/prevenção & controle , Futebol Americano/lesões , Protetores Bucais , Adolescente , Concussão Encefálica/epidemiologia , Lesões Encefálicas/epidemiologia , Humanos , Incidência , Masculino , Instituições Acadêmicas
10.
Artigo em Inglês | MEDLINE | ID: mdl-22111520

RESUMO

Dual-task methods have been used to demonstrate increased prioritization of walking performance over cognition in healthy aging. This is expressed as greater dual-task costs in cognitive performance than in walking. However, other research shows that older adults can prioritize cognitive performance over walking when instructed to do so. We asked whether age-related cognitive prioritization would emerge by experimentally manipulating cognitive difficulty. Young and older adults performed mental arithmetic at two levels of difficulty, alone or while walking. Electromyography and footswitches were used to measure muscle activity and stride parameters. Under high cognitive load, older adults increased their stride time, stride length, and hamstring activity, while maintaining their cognitive performance. Young adults showed negligible dual-task costs in each domain. The older adults appeared to successfully adapt their stride in response to high cognitive demands. The results have implications for neural models of gait regulation, and age differences in task emphasis.


Assuntos
Adaptação Fisiológica , Envelhecimento/fisiologia , Marcha/fisiologia , Desempenho Psicomotor/fisiologia , Caminhada/fisiologia , Adolescente , Adulto , Idoso , Cognição/fisiologia , Eletromiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/fisiologia , Equilíbrio Postural/fisiologia
11.
Ind Health ; 48(5): 682-97, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20953085

RESUMO

The vibration transmission to the lumbar and thoracic segments of seated human subjects exposed to whole body vibration of a vehicular nature have been mostly characterised without the back and hand supports, which is not representative of general driving conditions. This non-invasive experimental study investigated the transmission of vertical seat vibration to selected vertebrae and the head along the vertical and fore-aft axes of twelve male human subjects seated on a rigid seat and exposed to random vertical excitation in the 0.5-20 Hz range. The measurements were performed under four different sitting postures involving combinations of back support conditions and hands positions, and three difference magnitudes of vertical vibration (0.25, 0.5 and 1.0 m/s(2) rms acceleration). The results showed significant errors induced by sensor misalignment and skin effects, which required appropriate correction methodologies. The averaged corrected responses revealed that the back support attenuates vibration in the vertical axis to all the body locations while increasing the fore-aft transmissibility at the C7 and T5. The hands position generally has a relatively smaller effect, showing some influences on the C7 and L5 vibration. Sitting without a back support resulted in very low magnitude fore-aft vibration at T5, which was substantially higher with a back support, suggestive of a probable change in the body's vibration mode. The effect of back support was observed to be very small on the horizontal vibration of the lower thoracic and lumbar regions. The results suggest that distinctly different target body-segment biodynamic functions need to be defined for different support conditions in order to represent the unique contribution of the specific support condition. These datasets may then be useful for the development of biodynamic models.


Assuntos
Postura/fisiologia , Equipamentos de Proteção , Vibração/efeitos adversos , Aceleração/efeitos adversos , Adulto , Dorso/fisiologia , Fenômenos Biomecânicos/fisiologia , Movimentos da Cabeça/fisiologia , Humanos , Masculino
12.
J Gerontol B Psychol Sci Soc Sci ; 62(3): P171-8, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17507585

RESUMO

We examined the role of attention during different phases of the gait cycle by using a dual-task paradigm. Younger and older adults performed a self-paced treadmill walking task, a semantic judgment task, and both tasks simultaneously. We recorded vocal reaction time for the judgment task, and we recorded muscle activity by the use of electromyography. We derived dual-task costs from difference scores (single vs dual task). Our analysis of the judgment task showed that both groups responded more quickly during dual-task conditions than during single-task conditions. In five of eight muscle groups, stance-phase muscle activity decreased significantly from dual to single task. For older adults, individuals with poor balance increased their muscle activity during dual-task performance. These results suggest that, during moderately demanding walking and cognitive performance, poor balancers can compensate successfully for their motoric vulnerability.


Assuntos
Envelhecimento/fisiologia , Atenção/fisiologia , Contração Isométrica/fisiologia , Equilíbrio Postural/fisiologia , Caminhada/fisiologia , Idoso , Idoso de 80 Anos ou mais , Eletromiografia , Feminino , Marcha/fisiologia , Humanos , Individualidade , Julgamento , Masculino , Pessoa de Meia-Idade , Tempo de Reação/fisiologia , Semântica , Aprendizagem Verbal/fisiologia , Escalas de Wechsler
13.
Ind Health ; 43(3): 421-35, 2005 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16100919

RESUMO

The response characteristics of seated human subjects exposed to fore-aft (x-axis) and lateral (y-axis) vibration are investigated through measurements of dynamic interactions between the seated body and the seat pan, and the upper body and the seat backrest. The experiments involved: (i) three different back support conditions (no back support, and upper body supported against a vertical and an inclined backrest); (ii) three different seat pan heights (425, 390 and 350 mm); and three different magnitudes (0.25, 0.5 and 1.0 m/s2 rms acceleration) of band limited random excitations in the 0.5-10 Hz frequency range, applied independently along the fore-aft and lateral directions in an uncoupled manner. The body force responses, measured at the seat pan and the backrest along the direction of motion, are applied to characterize the total body apparent mass (APMS) reflected on the seat pan, and those of the upper body reflected on the backrest. Unlike the widely reported responses of seated occupants under vertical vibration, the responses to horizontal vibration show strong effect of excitation magnitude. The large displacements at lower frequencies cause considerable rotations of the upper body, and the knees and ankles, particularly when seated without a back support, which encouraged the occupants to continually shift larger portion of the body weight towards their feet. This together with the strong dependence on the excitation magnitude resulted in considerable inter-subject variability of the data. The addition of a back support causes stiffening of the body to limit the low frequency rocking motion of the upper body under x-axis motion, while considerable dynamic interactions with the backrest occur. The mean apparent mass (APMS) responses measured at the seat pan and the backrest suggest strong contributions due to the back support condition, and the direction and magnitude of horizontal vibration, while the role of seat height is important only in the vicinity of the resonant frequencies. In the absence of a back support, the seat pan responses predominate at a lower frequency (near 0.7 Hz) under both directions of motion, while two secondary peaks in the magnitude also occur at relatively higher frequencies. The addition of back support causes the seat pan response to converge mostly to a single primary peak, resulting in a single-degree-of-freedom like behavior, with peak occurring in the 2.7-5.4 Hz range under x-axis, and 0.9-2.1 Hz range under y-axis motions, depending upon the excitation magnitude and the back support condition. This can be attributed to the stiffening of the body in the presence of the constraints imposed by the backrest. A relaxed posture with an inclined backrest, however, causes a softening effect, when compared to an erect posture with a vertical backrest. The backrest, however, serves as another source of vibration to the seated occupant, which tends to cause considerably higher magnitude responses. The considerable magnitudes of the apparent mass response measured at the seat back under fore-aft motions suggest strong interactions with the backrest. Such interactions along the side-to-side motions, however, are relatively small. The results suggest that the biodynamic characterization of seated occupants exposed to horizontal vibration requires appropriate considerations of the interactions with the backrest.


Assuntos
Dorso , Postura/fisiologia , Equipamentos de Proteção , Vibração , Adulto , Condução de Veículo , Fenômenos Biomecânicos , Canadá , Humanos , Masculino , Pessoa de Meia-Idade
14.
J Athl Train ; 36(4): 369-375, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-12937478

RESUMO

OBJECTIVE: To assess the effects of sex, joint angle, and the gastrocnemius muscle on passive ankle joint complex stiffness (JCS). DESIGN AND SETTING: A repeated-measures design was employed using sex as a between-subjects factor and joint angle and inclusion of the gastrocnemius muscle as within-subject factors. All testing was conducted in a neuromuscular research laboratory. SUBJECTS: Twelve female and 12 male healthy, physically active subjects between the ages of 18 and 30 years volunteered for participation in this study. The dominant leg was used for testing. No subjects had a history of lower extremity musculoskeletal injury or circulatory or neurologic disorders. MEASUREMENTS: We determined passive ankle JCS by measuring resistance to passive dorsiflexion (5 degrees.s(-1)) from 23 degrees plantar flexion (PF) to 13 degrees dorsiflexion (DF). Angular position and torque data were collected from a dynamometer under 2 conditions designed to include or reduce the contribution of the gastrocnemius muscle. Separate fourth-order polynomial equations relating angular position and torque were constructed for each trial. Stiffness values (Nm.degree(-1)) were calculated at 10 degrees PF, neutral (NE), and 10 degrees DF using the slope of the line at each respective position. RESULTS: Significant condition-by-position and sex-by-position interactions and significant main effects for sex, position, and condition were revealed by a 3-way (sex-by-position, condition-by-position) analysis of variance. Post hoc analyses of the condition-by-position interaction revealed significantly higher stiffness values under the knee-straight condition compared with the knee-bent condition at both ankle NE and 10 degrees DF. Within each condition, stiffness values at each position were significantly higher as the ankle moved into DF. Post hoc analysis of the sex-by-position interaction revealed significantly higher stiffness values at 10 degrees DF in the male subjects. Post hoc analysis of the position main effect revealed that as the ankle moved into dorsiflexion, the stiffness at each position became significantly higher than at the previous position. CONCLUSIONS: The gastrocnemius contributes significantly to passive ankle JCS, thereby providing a scientific basis for clinicians incorporating stretching regimens into rehabilitation programs. Further research is warranted considering the cause and application of the sex-by-position interaction.

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