Lower Extremity Kinetics Research Articles

Influence of basketball shoe midsole inserts featuring different mechanical rebound properties on biomechanical loading and subjective perception during a side-cutting maneuver

This study examined the influence of basketball shoe midsole inserts with different forefoot and rearfoot rebound properties on biomechanical loading and subjective perception during a side-cutting maneuver. Eleven male basketball players executed side cutting in four shoe conditions mechanically characterized for their rearfoot/forefoot rebound: compliant/compliant, springy/springy, compliant/springy, and springy/compliant. Lower extremity kinetics and kinematics (normalized to body mass), as well as subjective perception, were measured. During the weight-acceptance phase, there were no differences between shoes in all biomechanical variables, except a slightly greater ankle range of motion (1.2° greater than the other three shoes) in the frontal plane for shoe compliant/springy. During the push-off phase, shoe springy/springy led to a greater ankle plantarflexion moment (1.21 Nm/kg greater than the other three shoes, p < 0.001) and knee internal rotation moment (0.09 Nm/kg greater than the other three shoes, p = 0.012), while shoe compliant/springy resulted in a greater ankle range of motion in the frontal plane (1.4° greater than the other three shoes, p < 0.001). Perception data showed no statistically significant difference among any shoes. In conclusion, springy inserts of basketball shoe midsoles induced a biomechanical loading effect. Perception of players being unaffected indicates the importance of biomechanical evaluation to examine the effects of the given shoe modifications during side cutting.

Hop-Stabilization Training and Landing Biomechanics in Athletes With Chronic Ankle Instability: A Randomized Controlled Trial.

Hopping exercises are recommended as a functional training tool to prevent lower limb injury, but their effects on lower extremity biomechanics in those with chronic ankle instability (CAI) are unclear. To determine if jump-landing biomechanics change after a hop-stabilization intervention. Randomized controlled clinical trial. Research laboratory. Twenty-eight male collegiate basketball players with CAI were divided into 2 groups: hop-training group (age = 22.78 ± 3.09 years, mass = 82.59 ± 9.51 kg, height = 187.96 ± 7.93 cm) and control group (age = 22.57 ± 2.76 years, mass = 78.35 ± 7.02 kg, height = 185.69 ± 7.28 cm). A 6-week supervised hop-stabilization training program that consisted of 18 training sessions. Lower extremity kinetics and kinematics during a jump-landing task and self-reported function were assessed before and after the 6-week training program. The hop-stabilization program resulted in improved self-reported function (P < .05), larger sagittal-plane hip- and knee-flexion angles, and greater ankle dorsiflexion (P < .05) relative to the control group. Reduced frontal-plane joint angles at the hip, knee, and ankle as well as decreased ground reaction forces and a longer time to peak ground reaction forces were observed in the hopping group compared with the control group after the intervention (P < .05). The 6-week hop-stabilization training program altered jump-landing biomechanics in male collegiate basketball players with CAI. These results may provide a potential mechanistic explanation for improvements in patient-reported outcomes and reductions in injury risk after ankle-sprain rehabilitation programs that incorporate hop-stabilization exercises.

External loading alters lower extremity kinetics, kinematics, and muscle activity in a distribution-specific manner during the transition from stair descent to level walking

BackgroundExcess body mass is thought to be a major cause of altered biomechanics in obesity, but the effects of body mass distribution in biomechanics during daily living tasks are unknown. The purpose of this study was to determine how increasing body mass centrally and peripherally affects lower extremity kinematics, kinetics, and muscle activation when transitioning from stair descent to level gait. MethodsFifteen normal weight volunteers descended a staircase at a self-selected pace under unloaded, centrally loaded, and peripherally loaded conditions. Spatial-temporal gait characteristics and lower extremity joint kinematics, kinetics, and mean electromyography amplitude were calculated using 3D motion analysis. FindingsBoth central and peripheral loading reduced gait velocity. Peripheral loading increased time spent in stance phase, increased step width, and reduced step length. At the hip joint, peripheral loading reduced peak hip extension and adduction angle. Conversely, central loading reduced peak hip flexor moment. Both central and peripheral loading increased peak knee flexion angle, but only peripheral loading increased peak knee extensor moment. Central and peripheral loading increased mean electromyography amplitude of the medial gastrocnemius, but only peripheral loading increased mean electromyography amplitude of the semitendinosus and the vastus medialis. InterpretationIncreasing mass centrally and peripherally differently affects spatial-temporal gait characteristics and lower extremity joint kinematics, kinetics, and electromyography when transitioning from stair descent to level gait. Body mass distribution may be an important factor for obesity-induced biomechanical alterations and should be considered when developing biomechanical models of obesity.

Anticipatory effects on lower extremity kinetics during a land and cross step maneuver in female volleyball players.

Anticipation has been previously shown to affect lower extremity mechanics during both landing and cutting maneuvers. However, little research has been conducted looking at the effects of anticipation on lower body kinetics and kinematics during a land and cross step maneuver, which due to similar kinematics, may elicit injury. The purpose of this study was to investigate competitive female volleyball players and the effect of anticipation on lower extremity mechanics during a landing and subsequent cross stepping maneuver. Twelve female, college-level volleyball players performed right and left cross step maneuvers following a landing under anticipated and unanticipated conditions. Kinetics were measured for the ankle, knee and hip of the dominant limb during the landing phase of the land and cross step anticipatory conditions. An interaction effect (anticipation x direction; P=0.001) was observed for vertical ground reaction force (VGRF), in which greater VGRF was found during unanticipated pivoting maneuvers. Additional interaction effects were determined for ankle (P=0.004) and hip (P=0.037) power absorption, in which greater absorption was found during anticipated, push off conditions. Frontal plant knee kinetics revealed a higher-order interaction, as a larger knee adduction moment was shown during anticipated, push off trials (P=0.001). High risk cross step maneuvers were found during unanticipated and anticipated conditions, as athletes demonstrated movement mechanics that may increase the risk of knee injury when performing movements away from the dominant limb. Consideration should be given to drills familiarizing volleyball players with unanticipated and anticipated changes of direction, as well as improving strength of the lower extremity muscles required to effectively decelerate the body, as both training modalities may minimize injury risk during cross step maneuvers.

Acute effects of different orthoses on lower extremity kinetics and kinematics during running; a musculoskeletal simulation analysis

The current investigation aimed to examine the effects of different orthotic conditions on the biomechanical mechanisms linked to the aetiology of chronic pathologies using musculoskeletal simulation. 16 male and 20 females ran over an embedded force plate at 4.0 m/s, in five different conditions (medial, lateral, no-orthoses, semi-custom and off the shelf). Kinematics of the lower extremities were collected using an eight-camera motion capture system and lower extremity joint loading also explored using a musculoskeletal simulation approach. Differences between orthoses conditions were examined using 2 × 2 mixed ANOVA. External instantaneous load rate was significantly reduced in the off the shelf orthoses (male = 1290.60 and female = 1567.10 N/kg/s), compared to the medial (male = 1480.45 and female = 1767.05 N/kg/s) and semi-custom (male = 1552.99 and female = 1704.37 N/kg/s) conditions. In addition, peak patellofemoral stress was significantly lower in the off the shelf orthoses (male = 68.55 and female = 94.91 KPa/kg) compared to the lateral condition (male = 70.49 and female = 103.22 KPa/kg). Finally, peak eversion angles were significantly attenuated in the medial orthoses (male = -6.61 and female = -7.72 deg) compared to the lateral (male = -9.61 and female = -10.32 deg), no-orthoses (male = -8.22 and female = -10.10 deg), semi-custom (male = -8.25 and female = -9.49 deg) and off the shelf (male = -7.54 and female = -8.85 deg) conditions. The current investigation shows that different orthotic devices⁄ configurations may provide distinct benefits in terms of their effectiveness in attenuating the biomechanical parameters linked to the aetiology of chronic running injuries.

Compensation or Recovery? Altered Kinetics and Neuromuscular Synergies Following High-Intensity Stepping Training Poststroke

Background. High-intensity, variable stepping training can improve walking speed in individuals poststroke, although neuromuscular strategies used to achieve faster speeds are unclear. We evaluated changes in joint kinetics and neuromuscular coordination following such training; movement strategies consistent with intact individuals were considered evidence of recovery and abnormal strategies indicative of compensation. Methods. A total of 15 individuals with stroke (duration: 23 ± 30 months) received ≤40 sessions of high-intensity stepping in variable contexts (tasks and environments). Lower-extremity kinetics and electromyographic (EMG) activity were collected prior to (BSL) and following (POST) training at peak treadmill speeds and speeds matched to peak BSL (MATCH). Primary measures included positive (concentric) joint and total limb powers, measures of interlimb (paretic/nonparetic powers) and intralimb compensation (hip/ankle or knee/ankle powers), and muscle synergies calculated using nonnegative matrix factorization. Results. Gains in most positive paretic and nonparetic joint powers were observed at higher speeds at POST, with decreased interlimb compensation and limited changes in intralimb compensation. There were very few differences in kinetic measures between BSL to MATCH conditions. However, the number of neuromuscular synergies increased significantly following training at both POST and MATCH conditions, indicating gains from training rather than altered speeds. Despite these results, speed improvements were associated primarily with changes in nonparetic versus paretic powers. Conclusion. Gains in locomotor function were accomplished by movement strategies consistent with both recovery and compensation. These and other data indicate that both strategies may be necessary to maximize walking function in patients poststroke.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P49. Effects of lower extremity fatigue and gender on unanticipated landing performance in a recurrent low back pain population

BACKGROUND CONTEXT Recurrent low back pain (rLBP) commonly affects the recreational and professional athlete alike, and correlation between rLBP and lower extremity injury has been well established. Previous data have shown strong correlation between a history of back pain and altered landing mechanics, trunk and lower extremity kinematics and kinetic factors all associated with increased lower extremity injury. Additionally, there has been direct proven correlation between neuromuscular core training programs and a decrease in lower extremity ligamentous injuries. Fatigue has also been proven to negatively affect trunk and lower extremity neuromuscular control, which may predispose to lower extremity injury. Well reported gender differences in lower extremity kinetics and kinematics are also known to alter propensity for injury. The complex interplay between these various factors is continuously being studied. Proper understanding of these risk factors for spine and leg injuries is imperative in establishing proper neuromuscular control rehabilitation and training programs to mitigate the risks of lower extremity injury, especially in patients with a history of low back pain. PURPOSE To determine the effects of fatigue and gender on trunk and knee mechanics, neuromuscular control, and ground reaction force (GRF) during drop vertical jump (DVJ) following by unanticipated landing or cutting in a population with rLBP. STUDY DESIGN/SETTING A prospective concurrent control cohort study. PATIENT SAMPLE Thirty-two adults with rLBP. OUTCOME MEASURES 3D knee and trunk motion, knee moments, and GRF. METHODS All test patients were fitted with a full body marker set. Surface EMG electrodes were placed bilaterally on trunk and lower extremity muscles. Each patient performed multiple 0.30 m DVJ landing and cutting in nonfatigued and fatigued conditions. RESULTS Fatigue altered landing mechanics with differences in landing performance between genders. For DVJ trials, females had greater knee internal rotation at initial contact (p=.001). Maximum knee flexion was reduced, but knee adduction (p=.026) and internal rotation (p=.009) and trunk flexion (p=.003) were greater at maximum knee flexion. Similar differences were also found during the cutting trials, with the addition of less trunk side flexion (p=.008) in females at maximum knee flexion. Females had smaller knee flexion moments (p=.021) during the DVJ. Fatigue resulted in less trunk flexion (p=.027) at initial contact for the DVJ, and greater trunk extension (p=.038) and trunk side flexion (p=.035) at maximum knee flexion, smaller maximum vertical GRF on the right leg, and maximum knee adduction moment when cutting. CONCLUSIONS Females with rLBP land differently than males and may have increased exposure to biomechanical factors that can contribute to lower extremity injury. Fatigue similarly alters landing and increases exposure to those same factors in this population. The majority of gender and fatigue related differences were consistent for unanticipated landing and cutting activities, which may better simulate actual sports activity. Armed with additional information of movement behaviors associated with increased lower extremity injuries, practitioners can design neuromuscular control training programs for women with rLBP and for men and women during fatigued conditions that serve a protective function and decrease the potential of ACL and other lower extremity injuries.

Non-linear changes of lower extremity kinetics prior to gait transition

IntroductionThe purpose of this study was to examine the changes of lower extremity kinetics during walk-to-run (WR) transition and if the changes would follow a non-linear trend within the five strides before WR transition using a constant acceleration protocol. MethodsFourteen participants performed gait transition on the instrumented treadmill at a constant acceleration. Peak, time to peak, and movement and power of hip, knee and ankle joints were recorded and analyzed in sagittal plane for five strides before gait transition. Three Two-way MANOVA were employed to examine the differences of kinetic measures among the five strides. Univariate analysis and Post-Hoc Tukey’s test would be applied if needed. Also, Post hoc polynomial trend analyses were used to examine the trend of the kinetic measures that significantly changed during the five strides. ResultsCompared to the first four strides, significant differences were observed for peaks moments, joint powers, and time to peaks in the last stride before running at ankle, knee, and hip joints respectively. In general, the changes of kinetic variables were following a quadratic trend during the five strides before running. ConclusionJoint kinetic measures actively change in non-linear patterns during the five strides before running to prepare for the gait transition, indicating that the gait transition is an active reorganization rather than a passive reaction.

Effects of Squat Depth and Stance Width on Lower Extremity Frontal Plane Kinetics

The squat is an exercise commonly used to improve lower-extremity (LE) strength and performance. Repeated frontal plane movement in the LE could have detrimental effects by contributing to certain joint pathologies. Therefore, investigating squat technique on LE kinetics is warranted. PURPOSE: This study compared hip and knee frontal plane kinetics during body-weight squats with varying depths and stance widths. METHODS: 11 healthy, college-aged participants (6 female, 5 male, height = 1.68 ± 0.08 m, mass = 67.4 ± 10.7 kg) performed 5 body squats at 100%, 150% and 200% of shoulder width for each of the following knee flexion angles: 55°, 90° and 125°. Trials were randomized and data were collected using Vicon Nexus and AMTI force plates. Frontal plane kinetics were processed using Visual 3D. RESULTS: At the hip, adduction moments showed significant increases as the width (100% = 0.301 ± 0.02, 150% = 0.539 ±0.04 and 200% = 0.736 ± 0.04; p < 0.001) and depth (55° = 0.306 ± 0.03 Nm/kg, 90°= 0.545 ± 0.04 Nm/kg and 125° = 0.725 ± 0.05 Nm/kg, p < 0.001) increased. At the knee, adduction moments significantly increased with wider stances (100% = 0.116 ± 0.02 Nm/kg, 150% = 0.178 ± 0.01 Nm/kg and 200% = 0.221 ± 0.01 Nm/kg; p < 0.001) while greater knee abduction moments were observed as depth of the squat increased (55° = 0.006 ± 0.02 Nm/kg, 90° = 0.147 ± 0.04 Nm/kg and 125° = 0.465 ± 0.05 Nm/kg; p < 0.001). CONCLUSION: Deep squats and larger stance widths may place greater demand on the hip and knee joints as evidenced by increased frontal plane moments. These data may benefit rehabilitation and strength training programs. For example, clinicians using squats as a rehabilitative exercise might decrease stance width when aiming to avoid LE frontal plane joint loading. Further, athletes who repeatedly stress the frontal plane stabilizing structures of the LE during dynamic movements may benefit from deeper and wider squats in training that would prepare these structures for their sport specific movements. Further research is needed to investigate other means of altering joint loading in the LE during exercise.

Effects of prophylactic knee bracing on patellar tendon loading parameters during functional sports tasks in recreational athletes

This study investigated the effects of prophylactic knee bracing on patellar tendon loading parameters. Twenty recreational athletes (10 male and 10 female) from different athletic disciplines performed run, cut and single leg hop movements under two conditions (prophylactic knee brace/no-brace). Lower extremity kinetics and kinematics were examined using a piezoelectric force plate and three-dimensional motion capture system. Patellar tendon loading was explored using a mathematical modelling approach, which accounted for co-contraction of the knee flexors. Tendon loading parameters were examined using 2 (brace) × 3 (movement) × 2 (sex) mixed ANOVAs. Tendon instantaneous load rate was significantly reduced in female athletes in the run (brace 289.14 BW/s no-brace 370.06 BW/s) and cut (brace 353.17 BW/s/no-brace 422.01 BW/s) conditions whilst wearing the brace. Female athletes may be able to attenuate their risk from patellar tendinopathy during athletic movements, through utilization of knee bracing, although further prospective research into the prophylactic effects of knee bracing is required before this can be clinically substantiated.

Evaluating the contribution of lower extremity kinetics to whole body power output during the power snatch

This study evaluated the contribution of lower extremity (hip, knee and ankle) net joint torques (NJT) to whole body power (WBP) output during the power snatch (PS). Ten experienced weightlifters (five males and five females) performed five trials of the PS with 60% of one repetition maximum. Lower extremity NJT and WBP were extracted through a three-dimensional motion analyses and used for data analyses. Pearson correlation coefficients were obtained to observe the relationship between lower extremity NJT and WBP. Multiple-regression (stepwise) analyses was also conducted to evaluate the contribution of lower extremity NJT to WBP during the PS with the hip, knee and ankle NJT being the independent variables. Hip NJT was characterised as a significant positive correlation with WBP (r = 0.47, p < 0.01), while knee NJT showed a significant negative correlation with WBP (r = −0.34, p < 0.05). A significant inter-correlation was also observed between hip NJT and knee NJT (r = −0.66, p < 0.01). Hip NJT was identified as a significant contributor to WBP during the PS. Practically, this study suggested that training skills allowing weightlifters to utilise hip extensor muscle action would help to improve WBP during the PS.

Patellar Tendon Straps Decrease Pain and May Alter Lower Extremity Kinetics in Those With Patellar Tendinopathy During Jump Landing

Patellar tendinopathy is often managed with a patellar tendon strap, however, their effectiveness is unsubstantiated. The purpose of this study was to determine if straps altered pain or lower extremity kinetics of individuals with patellar tendinopathy during landing. Thirty participants with patellar tendinopathy and 30 controls completed drop jumps with and without patellar tendon straps. Wearing the strap, tendinopathy participants demonstrated significantly decreased pain and reduced knee adductor moment; all participants displayed significantly decreased anterior ground reaction force while wearing a strap. Patellar tendon strapping may reduce pain due to alterations in direction and magnitude of loading.

임의 신호에 의한 방향 전환 동작 시 유도 전공 대학생들의 성별에 따른 하지 관절의 운동역학적 비교 분석

임의 신호에 의한 방향 전환 동작 시 유도 전공 대학생들의 성별에 따른 하지 관절의 운동역학적 비교 분석

Effect Of Excess Weight on Lower-Extremity Vertical Stiffness, Muscle Activation, And Metabolic Cost Of Walking

PURPOSE: To study the relationship between energy cost of walking (Cw), lower-extremity vertical stiffness (Kvert), and muscle activation across various BMIs. METHODS: This study compared Cw, Kvert, and muscle activation between obese (OB), normal weight (NW), and NW individuals carrying a load (NWL). A sample of 10 NW (24.2 ± 1.3 kg m-2) and 10 OB (33.1 ± 2.0 kg m-2) individuals (29.5 ± 11.7 yr, 14 females, 6 males) walked for six minutes on an instrumented treadmill at 1.25 m s-1 while oxygen uptake, muscle activation, and lower-extremity kinetics and kinematics were measured using an indirect calorimeter, electromyography, and a 3D optical motion tracking system, respectively. RESULTS: Cw was 24% greater in OB (277.5 ± 45.3 J m-1) compared to NW (211.0 ± 27.0 J m-1, P = 0.001), 23% greater in NWL (272.7 ± 35.7 J m-1) compared to NW (P = 0.002), but similar between OB and NWL (P = 0.955). Mass-specific Cw (Cwkg) was not statistically different between NW (2.99 ± 0.24 J m-1 kg-1) and OB (2.85 ± 0.18 J m-1 kg-1, P = 0.382), NW and NWL (2.74 ± 0.24 J m-1 kg-1, P = 0.071), or OB and NWL (P = 0.602), however a negative correlation (r = -0.44, P = 0.008) existed between BMI and Cwkg. Kvert was higher in OB (32.7 ± 5.2 kN m-1) than NW (23.3 ± 4.7 kN m-1, P < 0.001), but NWL (27.5 ± 3.4 kN m-1) was not different from either. Kvert per kilogram (P = 0.081) and muscle activation (P > 0.05) were similar across all conditions. A positive correlation existed between Kvert and Cw (r = 0.55, P = 0.001), but not when expressed per kilogram (r = 0.22, P = 0.120). Center of mass (COM) vertical displacement was similar between OB (3.3 ± 0.4 cm) and NW (3.5 ± 0.7 cm, P = 0.875), OB and NWL (3.9 ± 0.7 cm, P = 0.076), and NW and NWL (P = 0.194). Angle of attack between the leg and ground was similar between OB (104 ± 6 deg) and NW (106 ± 6 deg, P = 0.731) and between NW and NWL (110 ± 3 deg, P = 0.198), but 5% lower in OB than NWL (P = 0.045). CONCLUSION: Cwkg decreased from the NW to NWL condition. Kvert was greater at higher BMIs, but per kilogram was lower in NWL than OB likely due to NWL having a greater angle of attack and COM displacement. The linear relationship between Kvert and Cw is likely due to the greater muscle force needed to support larger body masses. Contrary to our hypothesis, Cwkg was not different between NW and OB and neither Kvert nor muscle activation explained the variability in Cwkg.

Joint Loading in the Sagittal Plane During Gait Is Associated With Hip Joint Abnormalities in Patients With Femoroacetabular Impingement

Background: Femoroacetabular impingement (FAI) is a morphological abnormality of the hip joint that results in functional impairments during various activities of daily living (ADL) such as walking. Purpose/Hypothesis: The purpose of this study was to determine if lower extremity joint loading differed between patients with FAI and controls and to determine whether these altered biomechanical parameters were associated with intra-articular abnormalities. It was hypothesized that patients with FAI would exhibit altered lower extremity joint loading during walking when compared with healthy controls and that these altered joint loading patterns would be associated with intra-articular abnormalities. Study Design: Controlled laboratory study. Methods: Lower extremity kinetics was assessed during walking at a self-selected speed in 15 presurgical patients with FAI and 34 healthy controls matched for age and body mass index. All participants underwent unilateral hip magnetic resonance imaging (MRI) to assess hip joint abnormalities. Hip joint abnormalities were assessed using a semiquantitative MRI-based scoring system. Self-reported outcomes of pain and function were obtained using the Hip disability and Osteoarthritis Outcome Score (HOOS), and physical performance was measured using the 6-minute walk test (6MWT). Group differences were assessed using an independent t test and analysis of variance. In the patients with FAI, associations of joint kinetics with HOOS subscores and intra-articular abnormalities were assessed using the Pearson (r) and Spearman (ρ) correlation coefficients, respectively. Results: Compared with the control group, the FAI group exhibited a significantly increased severity of acetabular (FAI: 1.87 ± 1.55; control: 0.47 ± 0.79; P < .001) and femoral (FAI: 3.27 ± 2.79; control: 1.21 ± 1.55; P = .002) cartilage abnormalities, increased levels of pain (FAI: 65.0 ± 18.8; control: 98.2 ± 3.4; P = .001), and reduced function (FAI: 67.2 ± 21.5; control: 98.9 ± 3.4; P < .001) but similar walking speeds (FAI: 1.55 ± 0.19 m/s; control: 1.63 ± 0.22 m/s; P = .20) and 6MWT performance (FAI: 628.0 ± 91.2 m; control: 667.2 ± 73.4 m; P = .13). The FAI group demonstrated increased hip flexion moment impulses (FAI: 0.14 ± 0.04 N·m·s/kg; control: 0.11 ± 0.03 N·m·s/kg; P = .03), peak ankle dorsiflexion moments (FAI: 1.64 ± 0.16 N·m/kg; control: 1.46 ± 0.31 N·m/kg; P = .04), and ankle dorsiflexion moment impulses (FAI: 0.39 ± 0.07 N·m·s/kg; control: 0.31 ± 0.07 N·m·s/kg; P = .01) compared with the control group. Within the FAI group, an increased hip flexion moment impulse during walking was significantly correlated with increased pain (r = −0.60, P = .03), decreased ADL (r = −0.57, P = .04), and increased severity of acetabular cartilage abnormalities (ρ = 0.82, P < .01). Conclusion: Patients with FAI exhibited altered hip and ankle joint loading patterns during walking. These data suggest that patients with FAI demonstrate both local and distal joint alterations during walking and that hip joint loading is directly related to hip joint abnormalities. Clinical Relevance: The results of this study suggest that the hip flexion moment impulse may be an important biomechanical parameter to understand FAI, as the hip flexion moment impulse during walking was shown to be directly related to hip joint abnormalities on MRI.

The influence of knee alignment on lower extremity kinetics during squats

The squat is an assessment of lower extremity alignment during movement, however there is little information regarding altered joint kinetics during poorly performed squats. The purpose of this study was to examine changes in joint kinetics and power from altered knee alignment during a squat. Thirty participants completed squats while displacing the knee medially, anteriorly, and with neutral alignment (control). Sagittal and frontal plane torques at the ankle, knee, and hip were altered in the descending and ascending phase of the squat in both the medial and anterior malaligned squat compared to the control squat. Ankle and trunk power increased and hip power decreased in the medial malaligned squat compared to the control squat. Ankle, knee, and trunk power increased and hip power decreased in the anterior malaligned squat compared to the control squat. Changes in joint torques and power during malaligned squats suggest that altered knee alignment increases ankle and trunk involvement to execute the movement. Increased anterior knee excursion during squatting may also lead to persistent altered loading of the ankle and knee. Sports medicine professionals using the squat for quadriceps strengthening must consider knee alignment to reduce ankle and trunk involvement during the movement.

Effects of load carriage and footwear on lower extremity kinetics and kinematics during overground walking

Kinetic and kinematic responses during walking vary by footwear condition. Load carriage also influences gait patterns, but it is unclear how an external load influences barefoot walking. Twelve healthy adults (5 women, 7 men) with no known gait abnormalities participated in this study (age=23±3years, height=1.73±0.11m, and mass=70.90±12.67kg). Ground reaction forces and 3D motion were simultaneously collected during overground walking at 1.5ms−1 in four conditions: Barefoot Unloaded, Shod Unloaded, Barefoot Loaded, and Shod Loaded. Barefoot walking reduced knee and hip joint ranges of motion, as well as stride length, stance time, swing time, and double support time. Load carriage increased stance and double support times. The 15% body weight load increased GRFs ∼15%. Walking barefoot reduced peak anteroposterior GRFs but not peak vertical GRFs. Load carriage increased hip, knee, and ankle joint moments and powers, while walking barefoot increased knee and hip moments and powers. Thus, spatiotemporal and kinematic adjustments to walking barefoot decrease GRFs but increase knee and hip kinetic measures during overground walking. The ankle seems to be less affected by these footwear conditions. Regardless of footwear, loading requires larger GRFs, joint loads, and joint powers.

Shape And Magnitude Of Lower Extremity Kinetics Changed Steps Before Gait Transition During Increasing Speed Induced Walk-to-run Transition

Shape And Magnitude Of Lower Extremity Kinetics Changed Steps Before Gait Transition During Increasing Speed Induced Walk-to-run Transition

The effect of tibiotalar alignment on coronal plane mechanics following total ankle replacement

BackgroundGait mechanics following total ankle replacement (TAR) have reported improved ankle motion following surgery. However, no studies have addressed the impact of preoperative radiographic tibiotalar alignment on post-TAR gait mechanics. We therefore investigated whether preoperative tibiotalar alignment (varus, valgus, or neutral) resulted in significantly different coronal plane mechanics or ground reaction forces post-TAR. MethodsWe conducted a non-randomized study of 93 consecutive end-stage ankle arthritis patients. Standard weight-bearing radiographs were obtained preoperatively to categorize patients as having neutral (±4°), varus (≥5° of varus), or valgus (≥5° of valgus) coronal plane tibiotalar alignment. All patients underwent a standard walking assessment including three-dimensional lower extremity kinetics and kinematics preoperatively, 12 and 24 months postoperatively. ResultsA significant group by time interaction was observed for the propulsive vertical ground reaction force (vGRF), coronal plane hip range of motion (ROM) and the peak hip abduction moment. The valgus group demonstrated an increase in the peak knee adduction angle and knee adduction angle at heel strike when compared to the other groups. Coronal plane ankle ROM, knee and hip angles at heel strike, and the peak hip angle exhibited significant increases across time. Peak ankle inversion moment, peak knee abduction moment and the weight acceptance vGRF also exhibited significant increases across time. Neutral ankle alignment was achieved for all patients by 2 years following TAR. ConclusionsRestoration of neutral ankle alignment at the time of TAR in patients with preoperative varus or valgus tibiotalar alignment resulted in biomechanics similar to those of patients with neutral preoperative tibiotalar alignment by 24-month follow-up.

Ankle and knee kinetics between strike patterns at common training speeds in competitive male runners

The purpose of this study was to investigate the interaction of foot strike and common speeds on sagittal plane ankle and knee joint kinetics in competitive rear foot strike (RFS) runners when running with a RFS pattern and an imposed forefoot strike (FFS) pattern. Sixteen competitive habitual male RFS runners ran at two different speeds (i.e. 8 and 6 min mile−1) using their habitual RFS and an imposed FFS pattern. A repeated measures analysis of variance was used to assess a potential interaction between strike pattern and speed for selected ground reaction force (GRF) variables and, sagittal plane ankle and knee kinematic and kinetic variables. No foot strike and speed interaction was observed for any of the kinetic variables. Habitual RFS yielded a greater loading rate of the vertical GRF, peak ankle dorsiflexor moment, peak knee extensor moment, peak knee eccentric extensor power, peak dorsiflexion and sagittal plane knee range of motion compared to imposed FFS. Imposed FFS yielded greater maximum vertical GRF, peak ankle plantarflexor moment, peak ankle eccentric plantarflexor power and sagittal plane ankle ROM compared to habitual RFS. Consistent with previous literature, imposed FFS in habitual RFS reduces eccentric knee extensor and ankle dorsiflexor involvement but produce greater eccentric ankle plantarflexor action compared to RFS. These acute differences between strike patterns were independent of running speeds equivalent to typical easy and hard training runs in competitive male runners. Current findings along with previous literature suggest differences in lower extremity kinetics between habitual RFS and imposed FFS running are consistent among a variety of runner populations.