Changes in the preferred transition speed with added mass to the foot.

This study was conducted to investigate whether adding mass to subjects' feet affects the preferred transition speed (PTS), and to ascertain whether selected swing phase variables (maximum ankle dorsiflexion angular velocity, angular acceleration, joint moment, and joint power) are determinants of the PTS, based upon four previously established criteria. After the PTS of 24 healthy active male subjects was found, using an incremental protocol in loaded (2 kg mass added to each shoe) and unloaded (shoes only) conditions, subjects walked at three speeds (60%, 80%, and 100% of PTS) and ran at one speed (100% of PTS) on a motor-driven treadmill while relevant data were collected. The PTS of the unloaded condition (2.

Tetherless ergonomics workstation to assess nurses' physical workload in a clinical setting.

Nurses are at risk of physical injury when moving immobile patients. This paper describes the development and testing of a tetherless ergonomics workstation that is suitable for studying nurses' physical workload in a clinical setting. The workstation uses wearable sensors to record multiple channels of body orientation and muscle activity and wirelessly transmits them to a base station laptop computer for display, storage, and analysis.

Cruciate ligament forces between short-step and long-step forward lunge.

Purpose: The purpose of this study was to compare cruciate ligament forces between the forward lunge with a short step (forward lunge short) and the forward lunge with a long step (forward lunge long).

Methods: Eighteen subjects used their 12-repetition maximum weight while performing the forward lunge short and long with and without a stride. EMG, force, and kinematic variables were input into a biomechanical model using optimization, and cruciate ligament forces were calculated as a function of knee angle.

Cruciate ligament tensile forces during the forward and side lunge.

Background: Although weight bearing lunge exercises are frequently employed during anterior cruciate ligament and posterior cruciate ligament rehabilitation, cruciate ligament tensile forces are currently unknown while performing forward and side lunge exercises with and without a stride.

Methods: Eighteen subjects used their 12 repetition maximum weight while performing a forward lunge and side lunge with and without a stride. A motion analysis system and biomechanical model were used to estimate cruciate ligament forces during lunging as a function of 0-90 degrees knee angles.

Suspected mechanisms in the cause of overuse running injuries: a clinical review.

Context: Various epidemiological studies have estimated that up to 70% of runners sustain an overuse running injury each year. Although few overuse running injuries have an established cause, more than 80% of running-related injuries occur at or below the knee, which suggests that some common mechanisms may be at work. The question then becomes, are there common mechanisms related to overuse running injuries?

Evidence Acquisition: RESEARCH STUDIES WERE IDENTIFIED VIA THE FOLLOWING ELECTRONIC DATABASES: MEDLINE, EMBASE PsycInfo, and CINAHL (1980-July 2008).

Patellofemoral joint force and stress during the wall squat and one-leg squat.

Purpose: To compare patellofemoral compressive force and stress during the one-leg squat and two variations of the wall squat.

Methods: Eighteen subjects used their 12 repetition maximum (12 RM) weight while performing the wall squat with the feet closer to the wall (wall squat short), the wall squat with the feet farther away from the wall (wall squat long), and the one-leg squat. EMG, force platform, and kinematic variables were input into a biomechanical model to calculate patellofemoral compressive force and stress as a function of knee angle.

Cruciate ligament force during the wall squat and the one-leg squat.

Purpose: To compare cruciate ligament forces during wall squat and one-leg squat exercises.

Methods: Eighteen subjects performed the wall squat with feet closer to the wall (wall squat short), the wall squat with feet farther from the wall (wall squat long), and the one-leg squat. EMG, force, and kinematic variables were input into a biomechanical model using optimization.

Patellofemoral joint force and stress between a short- and long-step forward lunge.

Study Design: Controlled laboratory biomechanics study using a repeated-measures, counterbalanced design.

Objectives: To compare patellofemoral joint force and stress between a short- and long-step forward lunge both with and without a stride.

Background: Although weight-bearing forward-lunge exercises are frequently employed during rehabilitation for individuals with patellofemoral joint syndrome, patellofemoral joint force and stress and how they change with variations of the lunge exercise are currently unknown.

Patellofemoral compressive force and stress during the forward and side lunges with and without a stride.

Background: Although weight bearing lunge exercises are frequently employed during patellofemoral rehabilitation, patellofemoral compressive force and stress are currently unknown for these exercises.

Methods: Eighteen subjects used their 12 repetition maximum weight while performing forward and side lunges with and without a stride. EMG, force platform, and kinematic variables were input into a biomechanical model, and patellofemoral compressive force and stress were calculated as a function of knee angle.

The relationship between joint kinetic factors and the walk-run gait transition speed during human locomotion.

The primary purpose of this project was to examine whether lower extremity joint kinetic factors are related to the walk-run gait transition during human locomotion. Following determination of the preferred transition speed (PTS), each of the 16 subjects walked down a 25-m runway, and over a floor-mounted force platform at five speeds (70, 80, 90, 100, and 110% of the PTS), and ran over the force platform at three speeds (80, 100, and 120% of the PTS) while being videotaped (240 Hz) from the right sagittal plane. Two-dimensional kinematic data were synchronized with ground reaction force data (960 Hz).

A Kinematic Comparison of the Judo Throw Harai-Goshi during Competitive and Non-Competitive Conditions.

The purpose of this study was to compare the kinematics of kuzushi/tsukuri (KT) phases of the harai-goshi throw under competitive and non-competitive conditions. A third degree black belt subject served as the tori (thrower) for both conditions. Two black belt participants ranked as first degree and fourth degree served as the uke (faller) for the competitive and non-competitive conditions, respectively.

When does a gait transition occur during human locomotion?

When a treadmill accelerates continuously, the walk-run transition has generally been assumed to occur at the instant when a flight phase is first observed, while the run-walk transition has been assumed to occur at the instant of the first double support period. There is no theoretical or empirical evidence to suggest that gait transitions occur at the instant of these events, nor even whether transitions are abrupt events. The purpose of this study was to determine whether the gait transitions during human locomotion occur abruptly, and if so, to determine the instant during a stride at which a transition occurs.

Effects of changing protocol, grade, and direction on the preferred gait transition speed during human locomotion.

Although the preferred transition speed (PTS) reported by various researchers is relatively consistent, the amount of observed hysteresis (difference between the walk-run and the run-walk transition speed) varies considerably. Variations in reported hysteresis appear to be related to the protocol used to determine the transition speeds. This investigation compared the PTS, and the amount of hysteresis observed between the incremental and continuous protocols at various inclination conditions.

An electromyographic analysis of commercial and common abdominal exercises: implications for rehabilitation and training.

Study Design: A repeated-measures, counterbalanced design.

Objectives: To test the effectiveness of 7 commercial abdominal machines (Ab Slide, Ab Twister, Ab Rocker, Ab Roller, Ab Doer, Torso Track, SAM) and 2 common abdominal exercises (crunch, bent-knee sit-up) on activating abdominal and extraneous (nonabdominal) musculature.

Background: Numerous abdominal machine exercises are believed to be effective in activating abdominal musculature and minimizing low back stress, but there are minimal data to substantiate these claims.

A three-dimensional analysis of the center of mass for three different judo throwing techniques.

Four black belt throwers (tori) and one black belt faller (uke) were filmed and analyzed in three-dimensions using two video cameras (JVC 60 Hz) and motion analysis software. Average linear momentum in the anteroposterior (x), vertical (y), and mediolateral (z) directions and average resultant impulse of uke's center of mass (COM) were investigated for three different throwing techniques; harai-goshi (hip throw), seoi-nage (hand throw), and osoto-gari (leg throw). Each throw was broken down into three main phases; kuzushi (balance breaking), tsukuri (fit-in), and kake (throw).

Preferred and energetically optimal transition speeds during backward human locomotion.

Some aspects of backward locomotion are similar to forward locomotion, while other aspects are not related to their forward counterpart. The backward preferred transition speed (BPTS) has never been directly compared to the energetically optimal transition speed (EOTS), nor has it been compared to the preferred transition speed (PTS) during forward locomotion. The purpose of this study was to determine whether the BPTS occurs at the EOTS, and to examine the relationship between the backward and forward preferred gait transition speeds.

Etiology, prevention, and early intervention of overuse injuries in runners: a biomechanical perspective.

Overuse running injuries occur frequently, and generally could be said to occur as a result of a runner maintaining a stress/frequency combination which puts a vulnerable musculoskeletal structure within the injury portion of a stress-frequency relationship. Given a runner's specific anthropometric and biomechanical stride characteristics, the causes of all overuse running injuries could be classified as training errors, and thus, all overuse running injuries should be preventable. One of the goals of future research should be to focus on developing simple screening processes that may assist medical practitioners in identifying runners who are at a high risk for overuse injury.

Impact and overuse injuries in runners.

Forces that are repeatedly applied to the body could lead to positive remodeling of a structure if the forces fall below the tensile limit of the structure and if sufficient time is provided between force applications. On the other hand, an overuse injury could result if there is inadequate rest time between applied forces. Running is one of the most widespread activities during which overuse injuries of the lower extremity occur.

Relationship between shock attenuation and stride length during running at different velocities.

The purpose of the study was to investigate the characteristics of shock attenuation during high-speed running. Maximal running speed was identified for each subject [n = 8 males, 25 (SD 4.6) years; 80 (8.

Foot strike patterns after obstacle clearance during running.

Purpose: Running over obstacles of sufficient height requires heel strike (HS) runners to make a transition in landing strategy to a forefoot (FF) strike, resulting in similar ground reaction force patterns to those observed while landing from a jump. Identification of the biomechanical variables that distinguish between the landing strategies may offer some insight into the reasons that the transition occurs. The purpose of this study was to investigate the difference in foot strike patterns and kinetic parameters of heel strike runners between level running and running over obstacles of various heights.