Biomedical subjects

Elizabeth S Chumanov

Publications and source records attributed to Elizabeth S Chumanov.

4 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

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↗