Biomedical subjects

Bryan C Heiderscheit

Publications and source records attributed to Bryan C Heiderscheit.

6 recordsLinked to original sources

PubMed2006

Neuromusculoskeletal models provide insights into the mechanisms and rehabilitation of hamstring strains.

Neuromusculoskeletal models are used to investigate hamstring mechanics during sprinting. We show that peak hamstring stretch occurs during late swing phase and is invariant with speed, but does depend on tendon compliance and the action of other muscles in the lumbopelvic region. The insights gained are relevant for improving the scientific basis of hamstring strain injury prevention and rehabilitation programs.

Biomechanical Phenomena↗

PubMed2005

Identifying the time of occurrence of a hamstring strain injury during treadmill running: a case study.

BACKGROUND: While hamstring strain injuries are common during sprinting, the mechanisms of injury are not well understood. In this study, we analyzed the running kinematics of an athlete obtained at the time of an acute hamstring strain injury. The purpose was to identify the period of the gait cycle during which the hamstring was likely injured, as well as to characterize the biomechanical conditions associated with the injury. METHODS: A male professional skier injured his right biceps femoris long head while running at 5.36 m/s on a treadmill with a 15% incline. Whole body kinematics were recorded at the time of injury. A linear periodic prediction model was used to determine when individual marker trajectories deviated from a cyclic periodic pattern, indicating the mechanical response to injury. A three-dimensional musculoskeletal model was used to compute joint angles and hamstring musculotendon lengths during the injurious running trial. These data were used with estimates of neuromuscular latencies and electromechanical delays to identify the most likely time period of injury. FINDINGS: Based upon the earliest indications in marker trajectories, a 130 ms period during the late swing phase of the gait cycle was identified as the period of injury. During this period, the biceps femoris reached a peak musculotendon length that was estimated to be 12% beyond the length seen in an upright posture and exceeded the normalized peak length of the medial hamstrings. INTERPRETATION: This case provides quantitative data suggesting that the biceps femoris muscle is susceptible to an lengthening contraction injury during the late swing phase of the running gait cycle.

Adult↗

PubMed2005

Gender differences in lower extremity coupling variability during an unanticipated cutting maneuver.

The purpose of this study was to determine if gender differences exist in the variability of various lower extremity (LE) segment and joint couplings during an unanticipated cutting maneuver. 3-D kinematics were collected on 24 college soccer players (12 M, 12 F) while each performed the cutting maneuver. The following intralimb couplings were studied: thigh rotation (rot)/leg rot; thigh abduction-adduction/leg abd-add; hip abd-add/knee rot; hip rot/knee abd-add; knee flexion-extension/knee rot; knee flx-ext/hip rot. A vector-coding technique applied to angle-angle plots was used to quantify the coordination of each coupling. The average between-trial standard deviation of the coordination pattern during the initial 40 % of stance was used to indicate the coordination variability. One-tailed t-tests were used to determine differences between genders in coordination variability for each coupling. Women had decreased variability in four couplings: 32 % less thigh rot/leg rot variability; 40 % less thigh abd-add/leg abd-add variability; 46 % less knee flx-ext/knee rot variability; and 44 % less knee flx-ext/hip rot variability. These gender differences in LE coordination variability may be associated with the increased incidence of ACL injury in women. If women exhibit less flexible coordination patterns during competition, they may be less able to adapt to the environmental perturbations experienced during sports. These perturbations applied to a less flexible system may result in ligament injury.

Adaptation, Physiological↗

PubMed2005

Hamstring muscle kinematics during treadmill sprinting.

INTRODUCTION/PURPOSE: The objective of this study was to characterize hamstring muscle kinematics during sprinting, so as to provide scientific data to better understand injury mechanisms and differences in injury rates between muscles. METHODS: We conducted three-dimensional motion analyses of 14 athletes performing treadmill sprinting at speeds ranging from 80 to 100% of maximum. Scaled musculoskeletal models were used to estimate hamstring muscle-tendon lengths throughout the sprinting gait cycle for each speed. We tested the hypothesis that the biceps femoris (BF) long head would be stretched a greater amount, relative to its length in an upright posture, than the semitendinosus (ST) and semimembranosus (SM). We also tested the hypothesis that increasing from submaximal to maximal sprinting speed would both increase the magnitude and delay the occurrence of peak muscle-tendon length in the gait cycle. RESULTS: Maximum hamstring lengths occurred during the late swing phase of sprinting and were an average of 7.4% (SM), 8.1% (ST), and 9.5% (BF) greater than the respective muscle-tendon lengths in an upright configuration. Peak lengths were significantly larger in the BF than the ST and SM (P < 0.01), occurred significantly later in the gait cycle at the maximal speed (P < 0.01), but did not increase significantly with speed. Differences in the hip extension and knee flexion moment arms between the biarticular hamstrings account for the intermuscle variations in the peak lengths that were estimated. CONCLUSIONS: We conclude that intermuscle differences in hamstring moment arms about the hip and knee may be a factor contributing to the greater propensity for hamstring strain injuries to occur in the BF muscle.

Adolescent↗

PubMed2005

Simulation of biceps femoris musculotendon mechanics during the swing phase of sprinting.

INTRODUCTION/PURPOSE: Characterization of hamstring mechanics during sprinting is fundamental to understanding musculotendon injury mechanisms. The objective of this study was to use muscle-actuated forward dynamic simulations to investigate musculotendon mechanics of the biceps femoris long head during the swing phase of sprinting. METHODS: We used a three-dimensional linked segment model with 26 Hill-type musculotendon actuators to simulate swing phase dynamics. Muscle excitations were computed that drove the linked segment model to track measured hip and knee motion of an individual sprinting on a treadmill. The simulations were used to investigate the effect of tendon compliance on the excursions and power development of the muscle and tendinous components of the biceps femoris. RESULTS: The biceps femoris musculotendon complex underwent a stretch-shortening cycle over the latter half of swing phase, with the shortening portion occurring in the final 10% of the gait cycle. Biceps femoris excitation increased markedly between 70 and 80% of the gait cycle and continued through the end of swing. Following the onset of excitation, stretch of the muscle component slowed considerably while the tendon lengthened and stored elastic energy. Simulating the sprinting movement with a more compliant tendon increased tendon elastic energy storage, thereby reducing peak muscle stretch and negative muscle work. CONCLUSIONS: Muscle-actuated forward dynamic simulation provides a powerful approach for investigating biomechanical factors that may contribute to the occurrence of hamstring musculotendon injuries.

Adolescent↗

PubMed2003

Limitations in the use and interpretation of continuous relative phase.

Continuous relative phase (CRP), a variable used to quantify intersegmental coordination, is difficult to interpret if care is not taken regarding the assumptions and limitations of the measure. Specifically, CRP is often interpreted as a higher resolution form of discrete relative phase (DRP). DRP, however, yields information regarding the relative dispersion of events in oscillatory signals while CRP describes their relationship in a higher order phase-plane domain. In this paper we address issues surrounding the calculation of CRP and suggest a new interpretation based on the aforementioned methodological issues. Through the use of test signals, with known properties, it was found that the CRP information will be arbitrary if no normalization procedures are used to account for frequency differences in the component oscillators. In addition, signals with non-sinusoidal trajectories will produce patterns in CRP that are not equivalent to discrete relative phase (DRP) measures. The implications of these issues are discussed.

Computer Simulation↗