Peter M. Quesada

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 ([Vdot]O2), expired ventilation ([Vdot]E), respiratory exchange ratio (RER)), heart rate (HR) and ratings of perceived exertion (RPE) were collected continuously during marching. Significant differences (p⩽0.05) were observed between each load for [Vdot]O2, HR and [Vdot]E throughout the marches. At 40 min, relative energy costs for 0%-BW, 15%-BW and 30%-BW loads were 30, 36 and 41% [Vdot]O2max, 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 premarch 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.

The Effect of Prehabilitation Exercise on Strength and Functioning After Total Knee Arthroplasty

The purpose of this study was to examine the effect of a preoperative exercise intervention on knee pain, functional ability, and quadriceps strength among patients with knee osteoarthritis before and after total knee arthroplasty (TKA) surgery.

Prehabilitation Before Total Knee Arthroplasty Increases Strength and Function in Older Adults With Severe Osteoarthritis

Swank, AM, Kachelman, JB, Bibeau, W, Quesada, PM, Nyland, J, Malkani, A, and Topp, RV. Prehabilitation before total knee arthroplasty increases strength and function in older adults with severe osteoarthritis. J Strength Cond Res 25(2): 318-325, 2011-Preparing for the stress of total knee arthroplasty (TKA) surgery by exercise training (prehabilitation) may improve strength and function before surgery and, if effective, has the potential to contribute to postoperative recovery. Subjects with severe osteoarthritis (OA), pain intractable to medicine and scheduled for TKA were randomized into a usual care (UC) group (n = 36) or usual care and exercise (UC + EX) group (n = 35). The UC group maintained normal daily activities before their TKA. The UC + EX group performed a comprehensive prehabilitation program that included resistance training using bands, flexibility, and step training at least 3 times per week for 4-8 weeks before their TKA in addition to UC. Leg strength (isokinetic peak torque for knee extension and flexion) and ability to perform functional tasks (6-minute walk, 30 second sit-to-stand repetitions, and the time to ascend and descend 2 flights of stairs) were assessed before randomization at baseline (T1) and 1 week before the subjects TKA (T2). Repeated-measures analysis of variance indicated a significant group by time interaction (p < 0.05) for the 30-second sit-to-stand repetitions, time to ascend the first flight of stairs, and peak torque for knee extension in the surgical knee. Prehabilitation increased leg strength and the ability to perform functional tasks for UC + EX when compared to UC before TKA. Short term (4-8 weeks) of prehabilitation was effective for increasing strength and function for individuals with severe OA. The program studied is easily transferred to a home environment, and clinicians working with this population should consider prehabilitation before TKA.

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.

Swimming as a Model of Task-Specific Locomotor Retraining After Spinal Cord Injury in the Rat

Background. The authors have shown that rats can be retrained to swim after a moderately severe thoracic spinal cord contusion. They also found that improvements in body position and hindlimb activity occurred rapidly over the first 2 weeks of training, reaching a plateau by week 4. Overground walking was not influenced by swim training, suggesting that swimming may be a task-specific model of locomotor retraining. Objective. To provide a quantitative description of hindlimb movements of uninjured adult rats during swimming, and then after injury and retraining. Methods. The authors used a novel and streamlined kinematic assessment of swimming in which each limb is described in 2 dimensions, as 3 segments and 2 angles. Results. The kinematics of uninjured rats do not change over 4 weeks of daily swimming, suggesting that acclimatization does not involve refinements in hindlimb movement. After spinal cord injury, retraining involved increases in hindlimb excursion and improved limb position, but the velocity of the movements remained slow. Conclusion. These data suggest that the activity pattern of swimming is hardwired in the rat spinal cord. After spinal cord injury, repetition is sufficient to bring about significant improvements in the pattern of hindlimb movement but does not improve the forces generated, leaving the animals with persistent deficits. These data support the concept that force (load) and pattern generation (recruitment) are independent and may have to be managed together with respect to postinjury rehabilitation.

Biomechanical evaluation of nursing tasks in a hospital setting

A field study was conducted to investigate spinal kinematics and loading in the nursing profession using objective and subjective measurements of selected nursing tasks observed in a hospital setting. Spinal loading was estimated using trunk motion dynamics measured by the lumbar motion monitor (LMM) and lower back compressive and shear forces were estimated using the three-dimensional (3D) Static Strength Prediction Program. Subjective measures included the rate of perceived physical effort and the perceived risk of low back pain. A multiple logistic regression model, reported in the literature for predicting low back injury based on defined risk groups, was tested. The study results concluded that the major risk factors for low back injury in nurses were the weight of patients handled, trunk moment, and trunk axial rotation. The activities that required long time exposure to awkward postures were perceived by nurses as a high physical effort. This study also concluded that self-reported perceived exertion could be used as a tool to identify nursing activities with a high risk of low-back injury.

Comparison of methods for the calculation of energy storage and return in a dynamic elastic response prosthesis

The standard method used to calculate the ankle joint power contains deficiencies when applied to dynamic elastic response prosthetic feet. The standard model, using rotational power and inverse dynamics, assumes a fixed joint center and cannot account for energy storage, dissipation, and return. This study compared the standard method with new analysis models. First, assumptions of inverse dynamics were avoided by directly measuring ankle forces and moments. Second, the ankle center of rotation was corrected by including translational power terms. Analysis with below-knee amputees revealed that the conventional method overestimates ankle forces and moments as well as prosthesis energy storage and return. Results for efficiency of energy return were varied. Large differences between models indicate the standard method may have serious inadequacies in the analysis of certain prosthetic feet. This research is the first application of the new models to prosthetic feet, and suggests the need for additional research in gait analysis with energy-storing prostheses.

Prehabilitation before knee arthroplasty increases postsurgical function: a case study.

Conditioning the body to undergo physical stress such as joint arthroplasty has been termed prehabilitation. This case study examined the effect of a 4-week prehabilitation intervention on functional outcomes after total knee arthroplasty (TKA). Two female subjects completed baseline strength and functional assessments before TKA. Subjects were randomized to either a 4-week prehabilitation intervention (ES) aimed at increasing strength and range of motion or a usual care condition (CS). After 4 weeks of training, subjects were reassessed and underwent TKA. Subjects completed a final assessment 12 weeks after TKA. Functional outcomes included 6-minute walk, number of times up from a chair in 30 seconds, proprioception, and self-reported function and pain using the Western Ontario and McMaster Universities Osteoarthritis Index. The data suggest that 4 weeks of prehabilitation had a positive effect on functional task performance and knee proprioception before surgery. After surgery, the ES continued to exhibit higher levels of functioning and less pain compared with the CS. Prehabilitation before TKA may contribute to improved recovery after surgery.

Kinematic evaluation of the finger’s interphalangeal joints coupling mechanism—variability, flexion–extension differences, triggers, locking swanneck deformities, anthropometric correlations

The human finger contains tendon/ligament mechanisms essential for proper control. One mechanism couples the movements of the interphalangeal joints when the (unloaded) finger is flexed with active deep flexor. This studys aim was to accurately determine in a large finger sample the kinematics and variability of the coupled interphalangeal joint motions, for potential clinical and finger model validation applications. The data could also be applied to humanoid robotic hands. Sixty-eight fingers were measured in seventeen hands in nine subjects. Fingers exhibited great joint mobility variability, with passive proximal interphalangeal hyperextension ranging from zero to almost fifty degrees. Increased measurement accuracy was obtained by using marker frames to amplify finger segment motions. Gravitational forces on the marker frames were not found to invalidate measurements. The recorded interphalangeal joint trajectories were highly consistent, demonstrating the underlying coupling mechanism. The increased accuracy and large sample size allowed for evaluation of detailed trajectory variability, systematic differences between flexion and extension trajectories, and three trigger types, distinct from flexor tendon triggers, involving initial flexion deficits in either proximal or distal interphalangeal joint. The experimental methods, data and analysis should advance insight into normal and pathological finger biomechanics (e.g., swanneck deformities), and could help improve clinical differential diagnostics of trigger finger causes. The marker frame measuring method may be useful to quantify interphalangeal joints trajectories in surgical/rehabilitative outcome studies. The data as a whole provide the most comprehensive collection of interphalangeal joint trajectories for clinical reference and model validation known to us to date.

Predictors of functional task performance among patients scheduled for total knee arthroplasty.

Brown, K, Kachelman, J, Topp, R, Quesada, PM, Nyland, J, Malkani, A, and Swank, AM. Predictors of functional task performance among patients scheduled for total knee arthroplasty. J Strength Cond Res 23(2): 436-443, 2009-Osteoarthritis (OA) is a common health problem affecting more than 7 million Americans. Declines in strength, flexibility, and knee joint pain reduce functional ability and contribute to decisions for total knee arthroplasty (TKA). This study describes predictors of functional ability among knee patients scheduled for TKA and proposes a preoperative exercise program to improve functional ability. A total of 82 knee OA patients (average age = 62.7 ± 7.48 years, 70% women) were recruited from a single orthopedic surgeons office. Muscular fitness assessments included knee flexion, extension strength, and range of motion (ROM) of the surgical and nonsurgical knees. Functional ability was assessed by 6-minute walk, number of chair rises in 30 seconds, and time required to ascend and descend 2 flights of stairs. Perceived functional ability and pain were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index. Correlation matrices determined which measures of muscular fitness, pain, and perceptions were associated with measures of functional ability. Significant correlates were entered into regression equations that determined the significant predictors of the functional tasks. These regression equations identified flexion strength of the nonsurgical knee as predicting 24-45% of the variance of functional ability assessments that involved independent or consecutive knee movement. Other variables that, to a lesser degree, predicted performance of the functional ability assessments included knee joint ROM and body mass index. Because functional ability after TKA is strongly dependent on presurgical functional ability, future investigators may wish to examine the impact of improving presurgical functional ability of TKA patients through resistance training, particularly closed-kinetic chain exercises that transfer fewer forces through the knee joint.