Vertical Ground Reaction Force Variables Research Articles

Association Between Patellar Tendon Abnormality and Land-Jump Biomechanics in Male Collegiate Basketball Players During the Preseason.

Patellar tendinopathy is a degenerative condition that predominantly affects jumping athletes. Symptoms may be subtle or nonexistent at preseason, but structural abnormalities may be present. Assessing patellar tendon abnormality (PTA) through magnetic resonance imaging (MRI) and ultrasound (US) and classifying symptoms using the Victorian Institute for Sport Assessment-Patellar tendon (VISA-P) may provide useful insights if combined with biomechanics measurements. To (1) assess whether land-jump biomechanical patterns are associated with clinically pertinent PTA as seen on imaging and through VISA-P scores and (2) model the contributing risk and accuracy of biomechanics to classify PTA and symptomatic observations. Cross-sectional study; Level of evidence, 3. A total of 26 National Collegiate Athletic Association Division I and II male basketball players (n = 52 limbs) were recruited during the preseason. We collected VISA-P scores, bilateral PTA through US and MRI morphology measurements, and bilateral 3-dimensional lower extremity kinematics and kinetics measurements from a land-jump test from an 18-inch-high (45.7-cm-high) box. Statistically, each limb was treated independently. The association of biomechanics with PTA and symptoms (VISA-P score <80) was tested with multivariate models and post hoc tests. Logistic regression modeled relative risk and accuracy of biomechanical variables to classify PTA and symptomatic limbs. There were 19 to 24 limbs with PTA depending on US and MRI measurements. Differences in hip and knee kinematic strategies and ground-reaction loads were associated with PTA and symptomatic limbs. Peak landing vertical ground-reaction force was significantly decreased (169 ± 26 vs 195 ± 29 %body weight; P = .001), and maximum hip flexion velocity was significantly increased (416 ± 74 vs 343 ± 94 deg/s; P = .005) in limbs with versus without PTA on imaging. Knee flexion at the initial contact was decreased in symptomatic versus healthy limbs (17°± 5° vs 21°± 5°, respectively; P = .045). Regression models classified PTA limbs and symptomatic limbs with 71.2% to 86.5% accuracy. Hip and knee maximum flexion velocity and vertical ground-reaction force variables were most common across models observing clinically pertinent PTA. Our findings suggested that functional kinematic and kinetic biomechanical strategies at the hip and knee were associated with PTA, identified on imaging, and symptomatic limbs.

The association between obesity, knee pain, and gait during stair descent in older adults with knee osteoarthritis

BackgroundObesity and knee osteoarthritis adversely affect activities of daily living in older adults. Together, the complexities of their interaction on mobility, including stair negotiation, are unresolved. The purpose of this study was to determine the relationship between obesity, pain, and stair negotiation in older adults with knee osteoarthritis. MethodsOlder adults with symptomatic knee osteoarthritis and overweight or obesity participated in the study (n = 28; age range = 57.0–78.0 yrs.; body mass index range = 26.6–42.8 kg•m−2). The Western Ontario and McMaster Universities Osteoarthritis Index pain subscale was used to measure knee pain. Measurements included a three-dimensional biomechanical analysis during descent on a set of force plate-instrumented stairs and a timed stair descent test. Pearson's r was used to determine associations between body mass index and pain, stair descent weight-acceptance phase vertical ground reaction force (vGRF) variables and lower extremity joint kinematics and kinetics, and timed stair descent performance. FindingsSignificant correlations existed between body mass index and pain (r = 0.41; p = 0.03), peak vGRF (r = 0.39; p = 0.04), vertical impulse (r = 0.49; p = 0.008), and peak ankle plantar flexor moments (r = 0.50; p = 0.007) in older adults with knee osteoarthritis. InterpretationGreater obesity in older adults with knee osteoarthritis was associated with greater knee pain and higher ankle joint loads during stair descent. These results support the recommendations of osteoarthritis treatment guidelines for weight-loss as a first-line of treatment for older adults with obesity and knee osteoarthritis.

Relationships Between Highly Skilled Golfers' Clubhead Velocity and Vertical Ground Reaction Force Asymmetry During Vertical Jumps and an Isometric Midthigh Pull

Wells, JET, Mitchell, ACS, Charalambous, LH, and Fletcher, IM. Relationships between highly skilled golfers' clubhead velocity and vertical ground reaction force asymmetry during vertical jumps and an isometric midthigh pull. J Strength Cond Res 34(10): 2824-2831, 2020-Clubhead velocity (CHV) is a commonly measured variable within golf due to strong associations with increased drive distance. Previous research has revealed significant relationships between CHV and vertical ground reaction force (vGRF) variables during bilateral tasks including a countermovement jump (CMJ), squat jump (SJ), drop jump (DJ), and isometric midthigh pull (IMTP). Asymmetries have been linked to performance outcomes in a number of sports; however, few studies have assessed asymmetries within golf. The current study, therefore, examined the relationships between CHV and vGRF asymmetries for CMJ positive impulse, SJ positive impulse, DJ positive impulse, and IMTP peak force (PF). Furthermore, the level of agreement for asymmetries between protocols was assessed by using Kappa coefficients. Fifty highly skilled (handicap ≤5) male golfers attended laboratory and range-based testing sessions. Positive impulse and PF were measured using a dual force platform system, with CHV measured using a TrackMan 3e launch monitor. There was no significant relationship (r = -0.14 to 0.22) between CHV and each of the vGRF asymmetry measures. Of the golfers tested, 26 had a "real" asymmetry in the CMJ, 18 had a "real" asymmetry in the SJ, 25 had a "real" asymmetry in the DJ, and 27 had a "real" asymmetry in the IMTP. Kappa coefficients indicated that asymmetries rarely favored the same limb (k = 0.06 to 0.39) with asymmetries varying for individual golfers between protocols. As such, asymmetries are neither beneficial nor detrimental to CHV but are inherently individual and dependent on the task.

Computed dynography, a method for evaluation of gait pattern in treated cases of congenital talipes equino varus

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; Club foot is characterized by inversion, adduction and equinus. Currently, evaluation of children treated for congenital talipes equino varus (CTEV) includes clinical and radiological examination as well as assessment of function. However, none of the methods is ideal. There should&lt;strong&gt; &lt;/strong&gt;be objective methods for better evaluation of function in treated CTEV. Gait analysis is the emerging method in objectively assessing the functional outcome. The aim of the study was to compare the selected measures from vertical ground reaction force variables and gait parameters of treated CTEV children with plantigrade feet, to healthy age and gender matched control group.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; We took 31 children with treated CTEV with mean age 8.21 years&lt;strong&gt; &lt;/strong&gt;and compared with 31 age and gender matched controls. The patients were initially treated under a standard protocol. Gait cycle properties, step time parameters and vertical ground reaction force variables were recorded and comparison of unilateral and bilateral cases of treated CTEV was done with that of controls.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; Data showed that despite good clinical results and overall function, residual intoeing, lateral foot walking, mild foot drop, weak plantar flexor power, possible residual inversion deformity of the foot, increased frequency and decreased duration of cycle and asymmetry in gait were the main characteristics of gait of children with treated CTEV. In unilateral cases single and double support times were decreased and in bilateral CTEV double support times are increased.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; The study confirms that in clubfoot patients who underwent full treatment, gait parameters do not reach normal levels. Gait analysis can be used to quantify gait pattern characteristics and is helpful in evaluation and further development of treatment of patients.&lt;/p&gt;

A Limb-specific Strategy across a Range of Running Speeds in Transfemoral Amputees.

This study investigated the vertical ground reaction force (vGRF) variables and spatiotemporal parameters related to running speed across a range of speeds in sprinters with unilateral transfemoral amputation who used running-specific prostheses (RSPs). Ten sprinters with unilateral transfemoral amputation ran on an instrumented treadmill at incremental speeds of 30%, 40%, 50%, 60%, and 70% of the average speed of their 100-m personal best (100%) while using their RSPs. The vGRF data were collected at 1000 Hz during each trial. We calculated the vGRF variables and spatiotemporal parameters, including the stance average vGRF (Favg), step frequency (Freqstep), and contact length (Lc; the length traveled by a runner's body during the stance phase). All three mechanical variables related to speed (Favg, Freqstep, and Lc) were similar for both the unaffected and affected limbs at relatively slower speeds, and these variables increased with speed for each limb. Although Freqstep remained similar between the limbs at relatively faster speeds, the affected limb exerted 11% smaller Favg and showed 12% longer Lc than the unaffected limb. These results suggest that, in order to achieve a faster running speed, runners with unilateral transfemoral amputation using RSPs likely adopt limb-specific biomechanical strategies for the unaffected and affected limbs, where the smaller Favg of the affected limb would be compensated by the longer Lc of the affected limb, without achieving a higher Freqstep.

Professional Dancers Distinct Biomechanical Pattern during Multidirectional Landings.

This study aimed to compare lower extremity (LE) biomechanics between professional dancers (PD) and nondancers (ND) during multidirectional single-leg landings. Fifteen PD (27 ± 7 yr, 1.69 ± 0.1 m, 57.8 ± 9.3 kg) and 15 ND (25 ± 5 yr, 1.69 ± 0.1 m, 66 ± 10.2 kg) performed single-leg jumps in three directions: 1) lateral, 2) diagonal, and 3) forward. Dominant LE biomechanical data were collected using a motion capture system. Data were processed in Visual3D. LE kinematic (hip, knee, and ankle joint angles in sagittal and frontal planes, and range of motion [ROM]) and kinetics (hip and knee internal joint moments and vertical ground reaction force) variables were analyzed at initial contact (IC), peak vertical ground reaction force (PvGRF), and peak knee flexion (PKF). Repeated-measures ANOVA was conducted (P < 0.05). At IC, statistically significant interactions were found for ankle frontal and hip sagittal angles (P < 0.05). The main effects for groups and jump directions were attained (P < 0.05). PD at IC had lower hip and knee flexion and higher ankle plantarflexion than ND. PD had significantly higher knee (PD, 41 ± 6.1; ND, 33.8 ± 8.4) and ankle (PD, 53.7 ± 3.4; ND, 38.9 ± 8.9) ROM than ND. At IC, the lateral jump had higher hip abduction moment, hip abduction, and ankle inversion and lower hip flexion and ankle plantarflexion than the forward and diagonal jumps. The lateral jump (15.5 ± 7.7) had higher hip excursion than the forward jump (12.7 ± 5.4). The higher extended posture of PD at IC promoted an efficient use of the knee and ankle ROM to dissipate the landing forces. Regardless of the group, jump directions also solicited different biomechanical responses, particularly between lateral and forward directions. These strategies should be considered for implementation in prevention programs, as it can foster adequate LE neuromuscular control.

Relationships between Challenge Tour golfers’ clubhead velocity and force producing capabilities during a countermovement jump and isometric mid-thigh pull

ABSTRACTA number of field-based investigations have evidenced practically significant relationships between clubhead velocity (CHV), vertical jump performance and maximum strength. Unfortunately, whilst these investigations provide a great deal of external validity, they are unable to ascertain vertical ground reaction force (vGRF) variables that may relate to golfers’ CHVs. This investigation aimed to assess if the variance in European Challenge Tour golfers’ CHVs could be predicted by countermovement jump (CMJ) positive impulse (PI), isometric mid-thigh pull (IMTP) peak force (PF) and rate of force development (RFD) from 0–50 ms, 0–100 ms, 0–150 ms and 0–200 ms. Thirty-one elite level European Challenge Tour golfers performed a CMJ and IMTP on dual force plates at a tournament venue, with CHV measured on a driving range. Hierarchical multiple regression results indicated that the variance in CHV was significantly predicted by all four models (model one R2 = 0.379; model two R2 = 0.392, model three R2 = 0.422, model four R2 = 0.480), with Akaike’s information criterion indicating that model one was the best fit. Individual standardised beta coefficients revealed that CMJ PI was the only significant variable, accounting for 37.9% of the variance in European Challenge Tour Golfers’ CHVs.

Kinematic predictors of loading during running differ by demographic group

ObjectivesTo investigate whether previously-determined kinematic predictors of kinetics during running differ between demographic groups. ParticipantsYoung male (n = 13, age = 22 (2) yrs), young female (n = 13, age = 25 (4) yrs), older male (n = 13, age = 50 (4) yrs) and older female (n = 13, age = 52 (3) yrs) runners. Main outcome measuresSagittal plane kinematics and kinetics were assessed while participants ran at their preferred pace. Linear regression models were developed to predict kinetics in each group using kinematics as independent variables. ResultsStep length was positively associated with magnitude of at least one kinetic variable in all groups. Step position was inversely associated with vertical ground reaction force variables in all groups. Step frequency and CoM excursion were also important to all groups, however direction of the associations varied. Foot angle at initial contact was important to all groups except older females. Peak knee flexion was most important to older females, but was not important to any other groups. ConclusionOptimal parameters for gait analysis of runners may depend on demographics of the individual. This provides insight for clinicians into the most effective evaluation and interventions strategies for different types of runners.

Sensor insole for measuring temporal variables and vertical force during sprinting

Temporal variables and vertical ground reaction force have been used as measures characterizing sprinting. A recently developed wireless pressure sensor insole (sensor insole) could be useful for monitoring sprinting in terms of temporal variables and vertical ground reaction force during training sessions. The purpose of this study was to examine the concurrent validity of the sensor insole for measuring temporal and vertical force variables during sprinting. One athlete performed five 50-m sprints, and the step-to-step vertical ground reaction force and plantar pressure were simultaneously measured by a long-force platform system (reference device) and the sensor insole, respectively. The temporal and vertical ground reaction force variables were calculated using signals from both devices, and a comparison was made between values obtained with both devices for 125 steps analyzed. The percentage bias, 95% limits of agreement, and Bland–Altman plots showed low agreement with the reference device for all variables except for step frequency. For the vertical ground reaction force variables, the sensor insole underestimated the values (−18.9 to −48.3%) compared to the force platform. While support time and time to maximal vertical force from the foot strike were overestimated by the sensor insole (54.6 ± 8.0% and 94.2 ± 23.2%), flight time was underestimated (−48.2 ± 15.0%). Moreover, t-test revealed the significant difference in all variables between the sensor insole and force platform, except for step frequency. The bias for step frequency (0.4 ± 7.5%) was small. However, there was heteroscedasticity for all variables. The results from this study demonstrate that a wireless pressure sensor insole is generally not valid to measure the temporal and vertical force variables during sprinting. Thus, using the examined sensor insole for monitoring sprinting characteristics is not recommended at this time.

Relationships between highly skilled golfers’ clubhead velocity and force producing capabilities during vertical jumps and an isometric mid-thigh pull

ABSTRACTWhilst previous research has highlighted significant relationships between golfers’ clubhead velocity (CHV) and their vertical jump height and maximum strength, these field-based protocols were unable to measure the actual vertical ground reaction force (vGRF) variables that may correlate to performance. The aim of this study was to investigate relationships between isometric mid-thigh pull (IMTP), countermovement jump (CMJ), squat jump (SJ) and drop jump (DJ) vGRF variables and CHV in highly skilled golfers. Twenty-seven male category 1 golfers performed IMTP, CMJ, SJ and DJ on a dual force platform. The vertical jumps were used to measure positive impulse during different stretch-shortening cycle velocities, with the IMTP assessing peak force (PF) and rate of force development (RFD). Clubhead velocity was measured using a TrackMan launch monitor at a golf driving range. Pearsons correlation coefficient analyses revealed significant relationships between peak CHV and CMJ positive impulse (r = 0.788, p < 0.001), SJ positive impulse (r = 0.692; p < 0.001), DJ positive impulse (r = 0.561, p < 0.01), PF (r = 0.482, p < 0.01), RFD from 0–150 ms (r = 0.343, p < 0.05) and RFD from 0–200 ms (r = 0.398, p < 0.05). The findings from this investigation indicate strong relationships between vertical ground reaction force variables and clubhead velocity.

8-week training in partial minimalist shoe reduces impact force during running

PurposeExcessive external load is a likely cause of running injuries. Although minimal running has been suggested as a possible approach to reduce impact and injury risk, an abrupt transition from conventional shoes to minimal running is also related to injuries. Therefore, the partial minimalist shoe has been suggested as a training strategy for a safe transition to minimal running. The study investigated if 8 weeks of training in partial minimalist shoe could improve impact control of shod and barefoot running.MethodsRecreational runners (12 men, 2 women), inexperienced in minimal running, performed 3 training sessions/week in partial minimalist shoes for 8 weeks. Before and after the intervention, the participants ran on a treadmill at 2.5 m/s under two conditions: in their habitual shoes and barefoot. Vertical ground reaction force (VGRF) was recorded.ResultsAfter the intervention, reduced values of the first peak (16.7% for shod, 36.7% for barefoot), time to reach the first peak (7.7% for shod, 30.2% for barefoot), and the load rate of the first peak (9.8% for shod, 9.5% for barefoot) were observed for both conditions (&lt;i&gt;p&lt;/i&gt; &lt; 0.001). Six subjects dropped out from the intervention.ConclusionsPartial minimalist training improved VGRF variables related to shock attenuation. Thus, the 8-week running training program with partial minimalist shoes was an effective approach to increase impact control. The intervention reduced the impact force in both shod and barefoot running, arising as a feasible option to progressively transition to minimal running.

Relationship between Dimensionless Leg Stiffness and Kinetic Variables during Gait Performance, and its Modulation with Body Weight

Objective: This purpose of this study was to analyze the relationship between dimensionless leg stiffness and kinetic variables during gait performance, and its modulation with body weight. Method: The study sample consisted of 10 young women divided into 2 groups (Control, n=5 and Obese, n=5). Four camcorders (HDR-HC7/HDV 1080i, Sony Corp, Japan) and one force plate (AMTI., USA) were used to analyze the vertical ground reaction force (GRF) variables, center of pressure (COP), low limb joint angle, position of pelvis center and leg lengths during the stance phase of the gait cycle. Results: Our results revealed that the center of mass (COM) displacement velocity along the y-axis was significantly higher in the obese group than that in control subjects. Displacement in the position of the center of the pelvis center (Z-axis) was also significantly higher in the obese group than that in control subjects. In addition, the peak vertical force (PVF) and dimensionless leg stiffness were also significantly higher in the obese group. However, when normalized to the body weight, the PVF did not show a significant between-group difference. When normalized to the leg length, the PVF and stiffness were both lower in the obese group than in control subjects. Conclusion: In the context of performance, we concluded that increased dimensionless leg stiffness during the gait cycle is associated with increased velocity of COM, PVF, and the change in leg lengths (%).

트레드밀 운동부하에 의한 피로가 수직 점프력과 지면반력 변인에 미치는 영향

트레드밀 운동부하에 의한 피로가 수직 점프력과 지면반력 변인에 미치는 영향

The Effect of Exertion and Sex on Vertical Ground Reaction Force Variables and Landing Mechanics.

The purpose of this investigation was to determine how exertion and sex affected a variety of vertical ground reaction force (VGRF) parameters during a jump-landing task, including peak VGRF, peak VGRF asymmetry, loading rate, and loading rate asymmetry. Additionally, we wanted to determine whether landing mechanics changed after exertion as measured by the Landing Error Scoring System (LESS). Forty recreationally active participants (20 men and 20 women) completed jump landings from a 30-cm-high box onto force plates before and after repeated bouts of an exercise circuit until a specific rating of perceived exertion was achieved. Three-way (sex × time × limb) analyses of variance were used to analyze variables pre-exertion to postexertion. No significant 3-way interactions were observed for peak VGRF (p = 0.31) or loading rate (p = 0.14). Time by sex interactions were observed for peak VGRF (p = 0.02) and loading rate (p = 0.008). Post hoc analysis revealed that men increased landing force and loading rate after exertion while women did not. Landing mechanics, as assessed by total LESS score, were worse after exertion (p < 0.001) with increased frequency of errors for knee flexion <30° at initial contact, lateral trunk flexion, and not flexing the hip during landing. Women may be more resistant to exertion compared with men and use different joint controls' strategies to cope with VGRF after exertion. However, VGRF asymmetry is not affected by sex and exertion. Limiting peak VGRF and addressing landing postures, especially after exertion, should be components of injury prevention strategies.

Does “transition shoe” promote an intermediate biomechanical condition compared to running in conventional shoe and in reduced protection condition?

This study evaluated if running in a “transition shoe” commercially available results in intermediate mechanical load upon lower extremities compared to conventional shoe and minimalist shoe/barefoot. Kinematic and kinetic parameters while running in different shoe conditions were compared. Fourteen runners (12 men, 2 women; age=28.4±7.3 years), inexperienced in minimalist shoes and barefoot running, ran on an instrumented treadmill within four experimental conditions (conventional shoe – CS, transition shoe – TrS, minimalist shoe – MS, and barefoot – BF). Running was performed at 9km/h for 10min in each experimental condition. Vertical ground reaction force (VGRF) and two-dimensional kinematic variables of lower limbs (both legs) were recorded. Nine data acquisitions (10s) were conducted for each footwear condition. Transition shoe lead to significant changes in VGRF variables related to impact control, while kinematic parameters were little affected. The TrS had smaller first peak of VGRF (Fy1) than CS (p≤0.001) and higher than MS (p=0.050) and BF (p≤0.001). Time to first peak of VGRF (tFy1) of TrS was smaller than CS (p≤0.001) and higher than MS (p≤0.001) and BF (p≤0.001). The TrS and MS induced to lesser knee flexion (p<0.001) and greater dorsiflexion (p<0.001) than CS and BF. Thus, results suggest the transition shoe (TrS) tested seem to promote an intermediate mechanical load condition only for VGRF parameters, presenting values of impact forces between those found for conventional shoe and minimalist shoe/barefoot. Such knowledge could be useful for the transition process from conventional running shoe to minimalist shoe/barefoot.

Influence of Familiarization and Competitive Level on the Reliability of Countermovement Vertical Jump Kinetic and Kinematic Variables.

Understanding typical variation of vertical jump (VJ) performance and confounding sources of its typical variability (i.e., familiarization and competitive level) is pertinent in the routine monitoring of athletes. We evaluated the presence of systematic error (learning effect) and nonuniformity of error (heteroscedasticity) across VJ performances of athletes that differ in competitive level and quantified the reliability of VJ kinetic and kinematic variables relative to the smallest worthwhile change (SWC). One hundred thirteen high school athletes, 30 college athletes, and 35 professional athletes completed repeat VJ trials. Average eccentric rate of force development (RFD), average concentric (CON) force, CON impulse, and jump height measurements were obtained from vertical ground reaction force (VGRF) data. Systematic error was assessed by evaluating changes in the mean of repeat trials. Heteroscedasticity was evaluated by plotting the difference score (trial 2 - trial 1) against the mean of the trials. Variability of jump variables was calculated as the typical error (TE) and coefficient of variation (%CV). No substantial systematic error (effect size range: -0.07 to 0.11) or heteroscedasticity was present for any of the VJ variables. Vertical jump can be performed without the need for familiarization trials, and the variability can be conveyed as either the raw TE or the %CV. Assessment of VGRF variables is an effective and reliable means of assessing VJ performance. Average CON force and CON impulse are highly reliable (%CV: 2.7% ×/÷ 1.10), although jump height was the only variable to display a %CV ≤SWC. Eccentric RFD is highly variable yet should not be discounted from VJ assessments on this factor alone because it may be sensitive to changes in response to training or fatigue that exceed the TE.

Analysis of Vertical Ground Reaction Force Variables Using Foot Scans in Hemiplegic Patients.

ObjectiveTo analyze the differences in the vertical ground reaction force (GRF) variables of hemiplegic patients compared with a control group, and between the affected and unaffected limbs of hemiplegic patients using foot scans.MethodsPatients (n=20) with hemiplegia and healthy volunteers (n=20) underwent vertical force analysis. We measured the following: the first and second peak forces (F1, F2) and the percent stances at which they occurred (T1, T2); the vertical force impulse (VFI) and stance times. The GRF results were compared between the hemiplegic patients and control individuals, and between the affected and unaffected limbs of hemiplegic patients. Additionally, we analyzed the impulse of the unaffected limb according to the motor assessment scale (MAS), Brunnstrom stage, and a Timed Up and Go Test.ResultsThe F1s and F2s of the affected and unaffected limbs were significantly less than those of the normal control individuals (p<0.05). The T1s of both the affected and unaffected limbs of the patients were greater than control individuals, whilst the T2s were lower (p<0.05). Greater impulses and stance times were recorded on both sides of the patients than in the limbs of the control individuals (p<0.05). The MAS, Brunnstrom stage and Timed Up and Go Test results were significantly correlated with the VFI of the unaffected limbs (p<0.05).ConclusionThe high impulse values of the unaffected limb were associated with complications during gait rehabilitation. Therefore, these results suggest that unaffected limbs should also be taken into consideration in these patients.

Weight-bearing asymmetry in individuals post-hip fracture during the sit to stand task

BackgroundIndividuals post hip fracture decrease force on the involved limb during sit to stand tasks, creating an asymmetry in vertical ground reaction force. Joint specific differences that underlie asymmetry of the vertical ground reaction force are unknown. The purpose of this study was to compare differences in vertical ground reaction force variables and joint kinetics at the hip and knee in participants post-hip fracture, who were recently discharged from homecare physical therapy to controls. MethodsForty-four community-dwelling older adults, 29 who had a hip fracture and 15 elderly control participant’s completed the sit to stand task on an instrumented chair with 3 force plates. T-tests were used to compare clinical tests (Berg Balance Scale, activity balance confidence and gait speed, isokinetic knee strength) and vertical ground reaction force variables. Two-way analyses of variance compared vertical ground reaction force variables and kinetics at the hip and knee between hip fracture and elderly control groups. Pearson correlation coefficients were used to determine correlations between clinical and vertical ground reaction force variables. FindingsVertical ground reaction force variables were significantly lower on the involved side for the hip fracture group compared to the uninvolved side and controls. Lower involved side hip and knee moments and power contributed to lower involved side vertical ground reaction force. Vertical ground reaction force variables and strength had moderate to high correlations with clinical measures. InterpretationUninvolved side knee moments and powers were the largest contributors to asymmetrical vertical ground reaction force in participants post-hip fracture. The association of vertical ground reaction force variables and clinical measures of function suggesting reducing vertical ground reaction force asymmetry may contribute to higher levels of function post-hip fracture. Functional and strength training should target the involved knee to reduce vertical ground reaction force asymmetry.

The reliability of biomechanical variables collected during single leg squat and landing tasks

IntroductionThe aim of this study was to determine the within- and between-day reliability of lower limb biomechanical variables collected during single leg squat (SLS) and single leg landing (SLL) tasks. Methods15 recreational athletes took part in three testing sessions, two sessions on the same day and another session one week later. Kinematic and kinetic data was gathered using a ten-camera movement analysis system (Qualisys) and a force platform (AMTI) embedded into the floor. ResultsThe combined averages of within-day ICC values (ICCSLS=0.87; ICCSLL=0.90) were higher than between-days (ICCSLS=0.81; ICCSLL=0.78). Vertical GRF values (ICCSLS=0.90; ICCSLL=0.98) were more reliable than joint angles (ICCSLS=0.85; ICCSLL=0.82) and moments (ICCSLS=0.83; ICCSLL=0.87). DiscussionThis study demonstrates that all joint angles, moments, and vertical ground reaction force (GRF) variables obtained during both tasks showed good to excellent consistency with relatively low standard error of measurement values. These findings would be of relevance to practitioners who are using such measures for screening and prospective studies of rehabilitative techniques.

Analysis of vertical ground reaction force variables by Foot scan in hemiplegic patients

Analysis of vertical ground reaction force variables by Foot scan in hemiplegic patients