KNEE POWER IN LOW BACK PAIN SUBJECTS DURING RUNNING

The purpose of this study was to examine lower extremity shock absorption between runners with and without low back pain. We compared data from three groups based on low back pain status: current low back pain, resolved pain after a single bout of low back pain and runners who never had low back pain (CTRL). All subjects ran at least 20 km per week and ran on a force treadmill at 3.8 m•s-1 while kinematic and kinetic data were collected. Work was determined from joint power histories during the shock attenuation portion of the stance phase. Individuals with a history of low back pain exhibited less peak knee negative power and negative work suggesting that they exhibited decreased eccentric muscle activity during foot-ground impact. The results of this study suggest that decreased eccentric activity of the muscles crossing the knee joint is associated with individuals who have low back pain and, to a lesser extent, with those who have residual low back pain. We suggest that the decreased eccentric activity can result in the footground impact shock wave moving through the lower extremity with little attenuation to the low back region

Lumbo-sacral loads and pelvis -trunk coordination in runners with chronic and resolved acute low back pain

The purpose of this dissertation was to investigate, in vivo, the effect of low back pain status on lumbo-sacral (L5S1) joint reaction force and moment profiles, and also on pelvis-trunk coordination during locomotion. We studied three groups of runners: runners with low to moderate LBP (LBP), runners who had recovered from a single bout of acute LBP (RES), and runners who never had LBP (CTRL). We developed an inverse dynamics model to investigate L5S1 mechanics. Results indicated that L5S1 reaction forces increased as stride length increased (p\u3c0.024) in healthy runners, as did peak sagittal L5S1 moments (p=0.078). Subsequently, we used this model to examine L5S1 differences between our three experimental groups at their preferred running speed and at 3.8 m/s. While differences were observed between speeds for many L5S1 variables, and between groups for peak vertical GRF, no differences were found between groups for lumbar angle ROM, peak L5S1 joint reaction force, or L5S1 joint moment. In a further study, pelvis and trunk range of motion (ROM), relative phase coordination (CRP) and coordination variability (CRPvar) were compared between our groups over a range of locomotor speeds. We found increased pelvis-trunk CRP in the frontal plane for the LBP group as compared to the CTRL group during walking (p=0.029). During running, we observed increased pelvis axial ROM for the LBP group as compared to CTRL (p=0.010), and increased CRP for CTRL as compared to both RES (p=0.021) and LBP group (p=0.025), and increased CRPvar for CTRL as compared to LBP group (p=0.019). Findings from the second and third studies demonstrated differences between clinical groups despite the relative low levels of disability (mean Modified Oswestry Disability Questionnaire score = 7.9±6.2%), and suggest that mechanical and coordinative differences exist between those with and without LBP. Further, our RES group demonstrated characteristics common to both extreme groups (CTRL and LBP), supporting previous literature regarding residual performance effects. Our findings further suggest that the RES group represented a transition stage between the CTRL and LBP groups

A history of low back pain affects pelvis and trunk coordination during a sustained manual materials handling task

Purpose: The purpose of this study was to compare the coordination between the trunk and the pelvis during a sustained asymmetric repetitive lifting task between a group with a history of low back pain (LBP; HBP) and a group with no history of LBP (NBP). Methods: Volunteers lifted a 11-kg box from ankle height in front to a shelf 45° off-center at waist height, and lowered it to the start position at 12 cycles/min for 10 min. Lifting side was alternated during the trial. Continuous relative phase was used to calculate coordination between the pelvis and trunk rotation at the beginning (Min 1), middle (Min 5), and end of the bout (Min 9). Results: While there were no main effects for group, a significant interaction between time and group indicated that, in the frontal plane, the NBP group coordination was more anti-phase toward the end of the bout, with no such differences for the HBP group. Analysis of sagittal-axial (bend and twist) coordination revealed the HBP group coordination was more in-phase at the end of the bout over the entire cycle and for the lifting phase alone, with no such differences for the NBP group. Conclusion: Differences between groups demonstrate residual consequences of LBP in an occupational scenario, even though the HBP group was pain-free for >6 months prior to data collection. More in-phase coordination in the HBP group may represent a coordination pattern analogous to “guarded gait” which has been observed in other studies, and may lend insight as to why these individuals are at increased risk for re-injury

Do older adults with knee osteoarthritis place greater loads on the knee during gait? A preliminary study

Messier SP, DeVita P, Cowan RE, Seay J, Young HC, Marsh AP. Do older adults with knee osteoarthritis place greater loads on the knee during gait? A preliminary study. Arch Phys Med Rehabil 2005;86:703–9. To compare the gait of older adults with knee osteoarthritis (OA) to an age-, sex-, and weight-matched healthy cohort that would provide preliminary data to examine the hypothesis that adults with knee OA have abnormal knee joint moments and place greater loads on the knee joint during walking compared with healthy adults. Nonrandomized, descriptive study of healthy and osteoarthritic older adults. University clinical research laboratory. Ten older adults with tibiofemoral and/or patellofemoral radiographic evidence and pain and disability attributed to knee OA and 10 age-, sex-, and weight-matched healthy adults. Not applicable. Three-dimensional gait analysis to calculate knee joint forces and hip, knee, and ankle joint moments; an analysis of covariance adjusted for differences in walking speed between the groups; electromyographic data to verify our interpretation of the knee joint moment data. The joint forces and moments did not differ statistically between the OA and healthy groups. Nonsignificant differences in the OA group relative to the healthy group included between 7% and 8% greater knee joint compressive (OA group, 3.67±0.24 body weight [BW]; healthy group, 3.40±0.24 BW) and shear (OA group, 0.47±0.04 BW; healthy group, .44±.04 BW) forces, 33% higher knee extension moments (OA group, .32±.07Nm/kg; healthy group, .24±.07Nm/kg), and 24% lower knee internal abduction moments (OA group, .25±.06Nm/kg; healthy group, .33±.06Nm/kg). Previous research suggests that mechanical overload may be associated with knee OA. Our results do not provide statistical evidence to support this hypothesis. Nevertheless, the trends in the data, along with previous results, suggest the need to investigate further the possible existence of a biomechanical pathway to knee OA

Running Mechanics and Variability with Aging.

Introduction: As the elderly population in the United States continues to grow, issues related to maintenance of health become increasingly important. Physical activity has positive benefits for healthy aging. Running, a popular form of exercise, is associated with the risk of developing injury, especially in older runners. Initial differences between older and younger runners have been observed, but these were observed without consideration of other differences between groups, such as running mileage. Purpose: This study aims to compare running mechanics and lower-extremity coordination variability in matched groups of healthy younger and healthy older runners