An Exploratory Investigation Evaluating the Impact of Fatigue-Induced Stride Length Compensations on Ankle Biomechanics among Skilled Baseball Pitchers.

Altered propulsive and bracing ground reaction forces from lower-body fatigue significantly impact stride length to increase weakness in dynamic elbow stabilizers and risk of medial elbow injury in baseball pitchers. This work investigated altered stride length on three-dimensional ankle joint dynamics to illustrate fatigue-induced changes in ankle motion that can also be impacted by coaching errors. Nineteen pitchers (15 collegiate and 4 high school) were randomized in a crossover design study that encouraged fatigue by throwing two simulated 80-pitch games at ±25% of their desired stride length.

Grip Strength Measurement in Baseball Pitchers: A Clinical Examination to Indicate Stride Length Inefficiency.

Background: Ulnar collateral ligament injuries are rampant in the sport of baseball where kinetic chain impacts, stemming from misappropriation of stride length or changes that occur in competition due to fatigue, have not been evaluated for dynamic elbow stability effects.

Hypothesis/purpose: To examine the relationship between clinical measures of grip strength and altered stride length in baseball pitchers. It is believed that shorter stride lengths would reduce grip strength in baseball pitchers.

Timing of Frontal Plane Trunk Lean, Not Magnitude, Mediates Frontal Plane Knee Joint Loading in Patients with Moderate Medial Knee Osteoarthritis.

The purpose of this study was to examine the influence of trunk lean and contralateral hip abductor strength on the peak knee adduction moment (KAM) and rate of loading in persons with moderate medial knee osteoarthritis. Thirty-one males (17 with osteoarthritis, 14 controls) underwent 3-dimensional motion analysis, strength testing of hip abductors, and knee range of motion (ROM) measures, as well as completing the knee osteoarthritis outcome score (KOOS). No differences were found between groups or limbs for gait cycle duration, but the osteoarthritis group had longer double-limb support during weight acceptance ( < 0.

Stride length: the impact on propulsion and bracing ground reaction force in overhand throwing.

Propulsion and bracing ground reaction force (GRF) in overhand throwing are integral in propagating joint reaction kinetics and ball velocity, yet how stride length effects drive (hind) and stride (lead) leg GRF profiles remain unknown. Using a randomised crossover design, 19 pitchers (15 collegiate and 4 high school) were assigned to throw 2 simulated 80-pitch games at ±25% of their desired stride length. An integrated motion capture system with two force plates and radar gun tracked each throw.

Multi-plane, multi-joint lower extremity support moments during a rapid deceleration task: Implications for knee loading.

The principle of lower limb support, and the contribution of hip, knee and ankle moments to an overall limb support strategy for an impact-like, rapid deceleration movement may help explain individual moment magnitude changes, thereby providing insight into how injury might occur or be avoided. Twenty subjects performed single limb, impact-like, deceleration landings at three different knee flexion angles in the range of 0-25, 25-50 and 50-75°. Kinematic and kinetic measures identified hip, knee and ankle moment contribution to limb support moments (LSMs) in three planes.

Impact of Physical Activities on Frailty in Community-Dwelling Older Women.

Aims: The aim of the study was to determine whether increased physical activities (PA) affect frailty for old women, 75 years and older (OO), compared to 60-74 years old (YO).

Methods: This crosssectional study measured 19 frailty indicators (muscle strength and endurance, balance, gait characteristics, and function), using 46 community-dwelling women. PA were divided into three levels by caloric expenditure per week (<2,000 kcal/week, 2,000-3,999 kcal/week,>4,000 kcal/week).

Effect of stride length on overarm throwing delivery: Part II: An angular momentum response.

This is the second component of a two-part series investigating 3D momentum profiles specific to overhand throwing, where altering stride reportedly influences throwing mechanics resulting in significantly different physiologic outcomes and linear momentum profiles. Using a randomized cross-over design, nineteen pitchers (15 collegiate and 4 high school) were assigned to pitch two simulated 80-pitch games at ±25% of their desired stride length. An 8-camera motion capture system (240Hz) integrated with two force plates (960Hz) and radar gun tracked each overhand throw.

An inferential investigation into how stride length influences temporal parameters within the baseball pitching delivery.

Motion analyses of lower body mechanics offer new schemas to address injury prevention strategies among baseball pitchers, where the influence of stride length remains unknown. This study examined the temporal effect of stride length at constituent pitching events and phases. Nineteen competitive pitchers (15 collegiate, 4 high school) were randomly assigned to pitch two simulated, 80-pitch games at ±25% of their desired stride length.

Effect of stride length on overarm throwing delivery: A linear momentum response.

Changing stride length during overhand throwing delivery is thought to alter total body and throwing arm linear momentums, thereby altering the proportion of throwing arm momentum relative to the total body. Using a randomized cross-over design, nineteen pitchers (15 collegiate and 4 high school) were assigned to pitch two simulated 80-pitch games at ±25% of their desired stride length. An 8-camera motion capture system (240Hz) integrated with two force plates (960Hz) and radar gun tracked each throw.

Altered stride length in response to increasing exertion among baseball pitchers.

Background: Overexertion caused by increased pitch counts can evoke protective biomechanical responses signified by decreased ball velocity, such as reduced throwing arm kinematics and kinetics. Among skilled pitchers, overexertion may not always present ball velocity decrements, because compensatory throwing biomechanics aid in maintaining peak ball velocity although lowering physiologic stress.

Methods: Nineteen pitchers (collegiate and elite high school), randomly crossed over to pitch two simulated games at ± 25% of their desired stride length, were recorded by an eight-camera motion capture system (240 Hz) integrated with two piezoelectric force plates (960 Hz) and a professional model radar gun.

Fastball velocity trends in short-season minor league baseball.

Diminishing baseball velocities are objective measures to delineate pitching fatigue. Yet, velocity changes over the course of a competitive season vs. a single game remain unknown.

A linear soft tissue artefact model for human movement analysis: proof of concept using in vivo data.

We investigated the accuracy of a linear soft tissue artefact (STA) model in human movement analysis. Simultaneously recorded bone-mounted pin and skin marker data for the thigh and shank during walking, cutting and hopping were used to measure and model the motion of the skin marker clusters within anatomical reference frames (ARFs). This linear model allows skin marker movements relative to the underlying bone contrary to a rigid-body assumption.

Do kinematic models reduce the effects of soft tissue artefacts in skin marker-based motion analysis? An in vivo study of knee kinematics.

We investigated the effects of including kinematic constraints in the analysis of knee kinematics from skin markers and compared the result to simultaneously recorded trajectories of bone pin markers during gait of six healthy subjects. The constraint equations that were considered for the knee were spherical and revolute joints, which have been frequently used in musculoskeletal modelling. In the models, the joint centres and joint axes of rotations were optimised from the skin marker trajectories over the trial.

Unloader braces for medial compartment knee osteoarthritis: implications on mediating progression.

Background: For persons with unicompartment knee osteoarthritis (OA), off-unloader braces are a mechanical intervention designed to reduce pain, improve physical function, and possibly slow disease progression. Pain relief is thought to be mediated by distracting the involved compartment via external varus or valgus forces applied to the knee. In so doing, tibiofemoral alignment is improved, and load is shifted off the degenerative compartment, where exposure to potentially damaging and provocative mechanical stresses are reduced.

Examining outcomes from total knee arthroplasty and the relationship between quadriceps strength and knee function over time.

Background: Temporal-spatial gait parameters improve following total knee arthroplasty (TKA) but lower limb kinematics and moments fail to match those of age-matched healthy individuals. The aim of this study was to determine whether quadriceps strength, clinical measures of knee function, lower limb kinematics, and joint moments improve following arthroplasty and normalize over time.

Methods: Twelve patients underwent total knee arthroplasty were tested at 3 and 12 months following surgery.

A mechanical theory for the effectiveness of bracing for medial compartment osteoarthritis of the knee.

Background: Evidence that knee braces used for the treatment of osteoarthritis mediate pain relief and improve function by unloading the joint (increasing the joint separation) remains inconclusive. Alternatively, valgus-producing braces may mediate pain relief by mechanically stabilizing the joint and reducing muscle cocontractions and joint compression. In this study, therefore, we sought to examine the degree to which so-called unloader braces control knee instability and influence muscle cocontractions during gait.

Effect of anatomic realignment on muscle function during gait in patients with medial compartment knee osteoarthritis.

Objective: Individuals with medial compartment knee osteoarthritis (OA) and genu varum use different movement and muscle activation patterns to increase joint stability during gait. The purpose of this study was to ascertain whether opening-wedge high-tibial osteotomy (OW-HTO) corrected pathomechanical abnormalities associated with the progression of knee OA.

Methods: Fifteen patients diagnosed with medial knee OA and genu varum who were scheduled for OW-HTO were tested prior to and 1 year following OW-HTO.

In vivo knee kinematics during gait reveals new rotation profiles and smaller translations.

In order to identify abnormal or pathological motions associated with clinically relevant questions such as injury mechanisms or factors leading to joint degeneration, it is essential to determine the range of normal tibiofemoral motion of the healthy knee. In this study we measured in vivo 3D tibiofemoral motion of the knee during gait and characterized the nonsagittal plane rotations and translations in a group of six healthy young adults. The subjects were instrumented with markers placed on intracortical pins inserted into the tibia and femur as well as marker clusters placed on the skin of the thigh and shank.

Effects of the amount of valgus correction for medial compartment knee osteoarthritis on clinical outcome, knee kinetics and muscle co-contraction after opening wedge high tibial osteotomy.

The goal of opening wedge high tibial osteotomy (HTO) is to reduce excessive loading on the medial compartment of the knee by correcting varus deformity, thereby reducing pain and improving function. Although surgical outcome is reportedly poor in cases of under- or overcorrection, the recommended alignment varies. The aim of this study was to investigate the effect of the degree of frontal plane knee alignment following open wedge HTO surgery on muscle co-contraction, joint moments, and self-reported functional outcome.

Effect of skin movement artifact on knee kinematics during gait and cutting motions measured in vivo.

Eight healthy male subjects had intra-cortical bone-pins inserted into the proximal tibia and distal femur. Three reflective markers were attached to each bone-pin and four reflective markers were mounted on the skin of the tibia and thigh, respectively. Roentgen-stereophotogrammetric analysis (RSA) was used to determine the anatomical reference frame of the tibia and femur.

Knee stabilization in patients with medial compartment knee osteoarthritis.

Objective: Individuals with medial knee osteoarthritis (OA) experience knee laxity and instability. Strategies aimed at muscle stabilization may influence the long-term integrity of the joint. This study sought to determine how individuals with medial knee OA respond to a rapid valgus knee movement, to investigate the relationship between muscle-stabilization strategies and knee instability.

Altered postural control during the luteal phase in women with premenstrual symptoms.

The purpose of this study was to investigate postural control in women with and without premenstrual symptoms (PMS) in three hormonally verified phases of the menstrual cycle. Thirty-two women were recruited to participate in the study and 25 of these women were included in the results. Menstrual cycle phases were determined by sex hormone analyses in serum and LH detection in urine.

Electromyographic and biomechanic analysis of anterior cruciate ligament deficiency and functional knee bracing.

Objective: Examine the neuromuscular response to functional knee bracing relative to anterior tibial translations in vivo.

Design: During randomised brace conditions, electromyographic data with simultaneous skeletal tibiofemoral kinematics were recorded from four anterior cruciate ligament deficient subjects to investigate the effect of the DonJoy Legend functional brace during activity.

Background: Knee braces do not increase knee stability but may influence afferent inputs from proprioception and therefore one might expect changes in muscle firing patterns, amplitude and timing.

Tibiofemoral contact points relative to flexion angle measured with MRI.

Objective: To determine whether knee flexion influenced bony contact movements during flexion.

Design: Accurate three-dimensional (3D) measurements of tibiofemoral bony contact points in vivo was performed using magnetic resonance imaging technology at 0 degrees, 30 degrees and 60 degrees of flexion.

Background: Magnetic resonance imaging is an accurate non-invasive tool for visualizing muscles, tendons, and bone, and provides precise 3D co-ordinates.