Biomedical subjects

P M Quesada

Publications and source records attributed to P M Quesada.

6 recordsLinked to original sources

PubMed2000

Biomechanical and metabolic effects of varying backpack loading on simulated marching.

Twelve healthy, male Army recruits performed three, 40-min treadmill marches at 6 km/h, under three load carriage conditions: 0%-body weight (BW) backpack load, 15%-BW load and 30%-BW load. Kinematic and kinetic data were obtained, immediately before and after each treadmill march, for computing ankle, knee and hip joint rotations and moments. Metabolic data (oxygen uptake (VO2), expired ventilation (VE), respiratory exchange ratio (RER)), heart rate (HR) and ratings of perceived exertion (RPE) were collected continuously during marching. Significant differences (p < or = 0.05) were observed between each load for VO2, HR and VE throughout the marches. At 40 min, relative energy costs for 0%-BW, 15%-BW and 30%-BW loads were 30, 36 and 41% VO2max, respectively. RPE responses during marching significantly differed for only the 30%-BW load and were greater than responses at 0%-BW and 15%-BW loads. During load carriage trials prior to treadmill marches (pre-march), peaks in internal, hip extension, knee extension and ankle plantar flexion moments increased with increasing backpack load. Relative to 0%-BW load, percentage increases in knee moments, due to 15%-BW and 30%-BW loads, pre-march, were substantially larger than the percentage increases for hip extension and plantar flexion moments, pre-march. Pre-march and post-march peaks in hip extension and ankle plantar flexion moments were similar with all loads, while notable pre-march to post-march declines were observed for knee extension moment peaks, at 15%-BW and 30%-BW load. Pre-march joint loading data suggests that the knee may be effecting substantial compensations during backpack loaded marching, perhaps to attenuate shock or reduce load elsewhere. Post-march kinetic data (particularly at 15%-BW and 30%-BW load), however, indicates that such knee mechanics were not sustained and suggests that excessive knee extensor fatigue may occur prior to march end, even though overall metabolic responses, at 15%-BW and 30%-BW load, remained within generally recommended limits to prevent fatigue during prolonged work.

Adolescent↗

PubMed2000

Wavelet-based noise removal for biomechanical signals: a comparative study.

The purpose of this paper is to present wavelet-based noise removal (WBNR) techniques to remove noise from biomechanical acceleration signals obtained from numerical differentiation of displacement data. Manual and semiautomatic methods were used to determine thresholds for both orthogonal and biorthogonal filters. This study also compares the performance of WBNR approaches with four automatic conventional noise removal techniques used in biomechanics. The conclusion of this work is that WBNR techniques are very effective in removing noise from differentiated signals with sharp transients while leaving these transients intact. For biomechanical signals with certain characteristics, WBNR techniques perform better than conventional methods, as indicated by quantitative merit measures.

Algorithms↗

PubMed2000

Biomechanical evaluation of a prototype foot/ankle prosthesis.

In this paper, we report on our pilot evaluation of a prototype foot/ankle prosthesis. This prototype has been designed and fabricated with the intention of providing decreased ankle joint stiffness during the middle portion of the stance phase of gait, and increased (i.e., more normal) knee range of motion during stance. Our evaluation involved fitting the existing prototype foot/ankle prosthesis, as well as a traditional solid ankle cushioned heel (SACH) foot, to an otherwise healthy volunteer with a below-knee (BK) amputation. We measured this individual's lower extremity joint kinematics and kinetics during walking using a video motion analysis system and force platform. These measurements permitted direct comparison of prosthetic ankle joint stiffness and involved side knee joint motion, as well as prosthetic ankle joint moment and power.

Adult↗

PubMed2000

Quantitative assessment of simultaneous capacitive and resistive plantar pressure measurements during walking.

Plantar pressure data were collected simultaneously, during walking, from capacitive and resistive in-shoe pressure measurement systems. Overall mean peak pressure recordings from the resistive system were 32%, 20% and 14% greater than recordings from the capacitive system, at the heel, central metatarsal heads, and great toe, respectively. Placement of one system's insoles above or below the other's somewhat affected peak pressure measurements from both systems, while calibration via air bladder or single limb standing techniques somewhat affected resistive measurements as well. Capacitive measurement variability was 60%, 20% and 22% lower than resistive measurement variability, at the heel, central metatarsal heads, and great toe, respectively. Both systems tended to exhibit greater variability when capacitive insoles were placed above resistive insoles; however, the effects on variability of the experimental insole arrangements were well overshadowed by the overall variability differences between systems.

Adult↗

PubMed1992

Lower-limb proprioception in above-knee amputees.

A proprioception measurement system was designed and constructed to evaluate lower-limb knee joint proprioception in ten above-knee amputees. The system permitted the testing of subjects in a position simulating late swing phase of gait. The threshold for detection of slow passive motion and the ability to reproduce specified lower-limb positions were recorded for the sound and the prosthetic limbs of the subjects. A significant difference was detected between prosthetic and sound limb passive motion detection threshold; however, no difference was found between prosthetic and sound limb passive motion reproduction. This finding suggests the importance of hip joint motion appreciation in the amputees' proprioception of the prosthetic knee joint when these motions are associated. Prosthetic limb passive motion reproduction error decreased with age, suggesting that the amputees may improve their ability to use remaining lower limb proprioceptive mechanisms to compensate for the loss of anatomic knee joint structures.

Adult↗

PubMedDate not supplied

Return of normal gait patterns after anterior cruciate ligament reconstruction.

Individuals with anterior cruciate ligament deficiency typically do not have quadriceps activity during stance. This aberrant pattern has been termed "quadriceps avoidance" gait. We performed gait analysis during walking on 10 normal controls and 10 subjects 8 to 12 months after they had anterior cruciate ligament reconstruction using autogenous middle third of the patellar tendon. All patients had good subjective and objective results at the time of analysis. Differences in gait between subjects and controls persisted up to 12 months after surgery. Specifically, subjects with anterior cruciate ligament reconstructions demonstrated significant reductions in midstance knee flexion moments (P < 0.01) and tibially directed loading rates (P < 0.05) when compared with controls. However, the subjects had a net external flexion moment throughout most of the stance phase of gait, implying that quadriceps activity was present. After anterior cruciate ligament reconstruction, there is a tendency toward gait normalization, and a quadriceps avoidance mechanism is no longer present.

Anterior Cruciate Ligament↗