Elora C. Brenneman

GT3X+ accelerometer placement affects the reliability of step-counts measured during running and pedal-revolution counts measured during bicycling

ABSTRACT Accelerometers provide a measure of step-count. Reliability and validity of step-count and pedal-revolution count measurements by the GT3X+ accelerometer, placed at different anatomical locations, is absent in the literature. The purpose of this study was to investigate the reliability and validity of step and pedal-revolution counts produced by the GT3X+ placed at different anatomical locations during running and bicycling. Twenty-two healthy adults (14 men and 8 women) completed running and bicycling activity bouts (5 minutes each) while wearing 6 accelerometers: 2 each at the waist, thigh and shank. Accelerometer and video data were collected during activity. Excellent reliability and validity were found for measurements taken from accelerometers mounted at the waist and shank during running (Reliability: intraclass correlation (ICC) ≥ 0.99; standard error of measurement (SEM) ≤1.0 steps; Validity: Pearson ≥ 0.99) and at the thigh and shank during bicycling (Reliability: ICC ≥ 0.99; SEM ≤1.0 revolutions; Validity: Pearson ≥ 0.99). Excellent reliability was found between measurements taken at the waist and shank during running (ICC ≥ 0.98; SEM ≤1.6 steps) and between measurements taken at the thigh and shank during bicycling (ICC ≥ 0.99; SEM ≤1.0 revolutions). These data suggest that the GT3X+ can be used for measuring step-count during running and pedal-revolution count during bicycling. Only shank placement is recommended for both activities.

Knee Extensor Power Relates to Mobility Performance in People With Knee Osteoarthritis: Cross-Sectional Analysis

Background Quadriceps femoris muscle strengthening is a common rehabilitation exercise for knee osteoarthritis (OA). More information is needed to determine whether targeting muscle power is a useful adjunct to strengthening for people with knee OA. Objective The purpose of this study was to identify the predictive ability of knee extensor strength and knee extensor power in the performance of physical tasks in adults with knee OA. Design This study used a cross-sectional design. Methods Fifty-five participants with clinical knee OA were included (43 women; mean [SD] age=60.9 [6.9] years). Dependent variables were: timed stair ascent, timed stair descent, and the Six-Minute Walk Test (6MWT). Independent variables were: peak knee extensor strength and mean peak knee extensor power. Covariates were: age, body mass index, and self-efficacy. Multiple regression analyses were run for each dependent variable with just covariates, then a second model including strength, and then a third model including power. The R2 values were compared between models. Results Power explained greater variance than strength in all models. Over and above the covariates, power explained an additional 6% of the variance in the 6MWT, increasing the R2 value from .33 to .39; 8% in the stair ascent test, increasing the R2 value from .52 to .60; and 3% in the stair descent test, increasing the R2 value from .44 to .47. Limitations The sample demonstrated very good mobility and muscle function scores and may not be indicative of those with severe knee OA. Conclusions In adults with knee OA, knee extensor power was a stronger determinant of walking and stair performance when compared with knee extensor strength. Clinicians should consider these results when advising patients on exercise to maintain or improve mobility.

A Yoga Strengthening Program Designed to Minimize the Knee Adduction Moment for Women with Knee Osteoarthritis: A Proof-Of-Principle Cohort Study.

People with knee osteoarthritis may benefit from exercise prescriptions that minimize knee loads in the frontal plane. The primary objective of this study was to determine whether a novel 12-week strengthening program designed to minimize exposure to the knee adduction moment (KAM) could improve symptoms and knee strength in women with symptomatic knee osteoarthritis. A secondary objective was to determine whether the program could improve mobility and fitness, and decrease peak KAM during gait. The tertiary objective was to evaluate the biomechanical characteristics of this yoga program. In particular, we compared the peak KAM during gait with that during yoga postures at baseline. We also compared lower limb normalized mean electromyography (EMG) amplitudes during yoga postures between baseline and follow-up. Primary measures included self-reported pain and physical function (Knee injury and Osteoarthritis Outcome Score) and knee strength (extensor and flexor torques). Secondary measures included mobility (six-minute walk, 30-second chair stand, stair climbing), fitness (submaximal cycle ergometer test), and clinical gait analysis using motion capture synchronized with electromyography and force measurement. Also, KAM and normalized mean EMG amplitudes were collected during yoga postures. Forty-five women over age 50 with symptomatic knee osteoarthritis, consistent with the American College of Rheumatology criteria, enrolled in our 12-week (3 sessions per week) program. Data from 38 were analyzed (six drop-outs; one lost to co-intervention). Participants experienced reduced pain (mean improvement 10.1–20.1 normalized to 100; p<0.001), increased knee extensor strength (mean improvement 0.01 Nm/kg; p = 0.004), and increased flexor strength (mean improvement 0.01 Nm/kg; p = 0.001) at follow-up compared to baseline. Participants improved mobility on the six-minute walk (mean improvement 37.7 m; p<0.001) and 30-second chair stand (mean improvement 1.3; p = 0.006) at follow-up compared to baseline. Fitness and peak KAM during gait were unchanged between baseline and follow-up. Average KAM during the yoga postures were lower than that of normal gait. Normalized mean EMG amplitudes during yoga postures were up to 31.0% of maximum but did not change between baseline and follow-up. In this cohort study, the yoga-based strengthening postures that elicit low KAMs improved knee symptoms and strength in women with knee OA following a 12 week program (3 sessions per week). The program also improved mobility, but did not improve fitness or reduce peak KAM during gait. The KAM during the yoga postures were lower than that of normal gait. Overall, the proposed program may be useful in improving pain, strength, and mobility in women with knee osteoarthritis. Clinical efficacy needs to be assessed using a randomized controlled trial design. Trial Registration ClinicalTrials.gov NCT02146105

Identifying yoga-based knee strengthening exercises using the knee adduction moment

BACKGROUND This study aimed to compare muscle activations, co-contraction indices, and the knee adduction moment between static standing yoga postures to identify appropriate exercises for knee osteoarthritis. METHODS Healthy young women (24.4 (5.4) years, 23.1 (3.7) kg/m(2)) participated. Primary outcome variables were electromyographic activations of the vastus lateralis, rectus femoris, vastus medialis, biceps femoris, and semitendinosus; co-contraction between the biceps femoris and rectus femoris, and vastus lateralis and vastus medialis; and knee adduction moments of both legs during six static, standing yoga postures (two squatting postures, two lunging postures, a hamstring stretch, and a single-leg balance posture). A two-factor repeated measures analysis of variance was used to identify differences in muscle amplitudes, co-contractions, and knee adduction moment between postures and legs. FINDINGS Quadriceps activations were highest during squat and lunge postures (p≤0.001). Hamstring activations were highest during the hamstring stretch (p≤0.003). Squat and lunge postures produced higher co-contraction indices than other postures (p≤0.011). The wide legged squat (Goddess) and lunge with trunk upright (Warrior) produced the lowest knee adduction moments (p≤0.006), while the single-leg balance posture elicited a higher knee adduction moment than all other postures (p<0.05). INTERPRETATION Squatting and lunging postures could improve leg strength while potentially minimizing exposure to high knee adduction moments. Future work should evaluate whether these exercises are useful in people with knee osteoarthritis.

Does pain relate with activation of quadriceps and hamstrings muscles during strengthening exercise in people with knee osteoarthritis

Muscle strengthening may be difficult to achieve in knee osteoarthritis (OA) due to pain. A large knee adduction moment (KAM), representing medial relative to lateral knee load, may also relate with pain during strengthening exercise. The objective of this study was to examine relationships between knee pain status and electromyography (EMG) amplitude of knee muscles during squat and lunge exercises. We also evaluated relationships between pain and KAM during these exercises. Forty-two women with symptomatic knee OA participated. Knee pain intensity and frequency were captured with two reliable and valid questionnaires. Motion analyses of squat and lunge exercises were completed. Total average EMG amplitude across five muscles of the lower limb and average KAM were calculated from the static portion of these exercises. Multiple regression analyses examined the relationships between pain and total average EMG amplitude; and pain and average KAM during squats and lunges. Pain improved the model for KAM from the trailing leg of a lunge. Pain did not improve any other model. Overall, pain may not be a useful indicator of EMG amplitude or KAM during exercise in knee OA.

Identifying changes in gait waveforms following a strengthening intervention for women with knee osteoarthritis using principal components analysis

Lower limb strengthening exercise is pivotal for the management of symptoms related to knee osteoarthritis (OA). Though improvement in clinical symptoms is well documented, concurrent changes in gait biomechanics are ill-defined. This may occur because discrete analyses miss changes following an intervention, analyses limited to the knee undermine potential mechanical trade-offs at other joints, or strengthening interventions not been designed based on biomechanical principles. The purpose of this study was to characterize differences in entire gait waveforms for sagittal plane ankle, knee, and hip angles and external moments; the knee adduction moment; and frontal plane hip angle and moment following 12-weeks of a previously designed novel lower limb strengthening program. Forty women with knee OA completed two laboratory visits: one at baseline and one immediately following intervention (follow-up). Self-report measures, strength, and gait analyses were completed at each visit. Principal components analyses were completed for sagittal angles and external moments at the ankle, knee, and hip joints, as well as frontal plane angle and moment for the hip. Participants improved self-report and strength (p≤0.004). Two significant, yet subtle differences in principal components were identified between baseline and follow-up waveforms (p<0.05) pertaining to the knee and hip sagittal external moments. The subtle changes in concert with the lack of differences in other joints and planes suggest the lower limb strengthening program does not translate to changes in the gait waveform. It is likely this program is improving symptoms without worsening mechanics.

Acute changes in knee cartilage transverse relaxation time after running and bicycling

PURPOSE To compare the acute effect of running and bicycling of an equivalent cumulative load on knee cartilage composition and morphometry in healthy young men. A secondary analysis investigated the relationship between activity history and the change in cartilage composition after activity. METHODS In fifteen men (25.8±4.2 years), the vertical ground reaction force was measured to determine the cumulative load exposure of a 15-min run. The vertical pedal reaction force was recorded during bicycling to define the bicycling duration of an equivalent cumulative load. On separate visits that were spaced on average 17 days apart, participants completed these running and bicycling bouts. Mean cartilage transverse relaxation times (T2) were determined for cartilage on the tibia and weight-bearing femur before and after each exercise. T2 was measured using a multi-echo spin-echo sequence and 3T MRI. Cartilage of the weight bearing femur and tibia was segmented using a highly-automated segmentation algorithm. Activity history was captured using the International Physical Activity Questionnaire. RESULTS The response of T2 to bicycling and running was different (p=0.019; mean T2: pre-running=34.27ms, pre-bicycling=32.93ms, post-running=31.82ms, post-bicycling=32.36ms). While bicycling produced no change (-1.7%, p=0.300), running shortened T2 (-7.1%, p<0.001). Greater activity history predicted smaller changes in tibial, but not femoral, T2. CONCLUSIONS Changes in knee cartilage vary based on activity type, independent of total load exposure, in healthy young men. Smaller changes in T2 were observed after bicycling relative to running. Activity history was inversely related to tibial T2, suggesting cartilage conditioning.

Efficacy of a biomechanically-based yoga exercise program in knee osteoarthritis: A randomized controlled trial

Objective Certain exercises could overload the osteoarthritic knee. We developed an exercise program from yoga postures with a minimal knee adduction moment for knee osteoarthritis. The purpose was to compare the effectiveness of this biomechanically-based yoga exercise (YE), with traditional exercise (TE), and a no-exercise attention-equivalent control (NE) for improving pain, self-reported physical function and mobility performance in women with knee osteoarthritis. Design Single-blind, three-arm randomized controlled trial. Setting Community in Southwestern Ontario, Canada. Participants A convenience sample of 31 women with symptomatic knee osteoarthritis was recruited through rheumatology, orthopaedic and physiotherapy clinics, newspapers and word-of-mouth. Interventions Participants were stratified by disease severity and randomly allocated to one of three 12-week, supervised interventions. YE included biomechanically-based yoga exercises; TE included traditional leg strengthening on machines; and NE included meditation with no exercise. Participants were asked to attend three 1-hour group classes/sessions each week. Measurements Primary outcomes were pain, self-reported physical function and mobility performance. Secondary outcomes were knee strength, depression, and health-related quality of life. All were assessed by a blinded assessor at baseline and immediately following the intervention. Results The YE group demonstrated greater improvements in KOOS pain (mean difference of 22.9 [95% CI, 6.9 to 38.8; p = 0.003]), intermittent pain (mean difference of -19.6 [95% CI, -34.8 to -4.4; p = 0.009]) and self-reported physical function (mean difference of 17.2 [95% CI, 5.2 to 29.2; p = 0.003]) compared to NE. Improvements in these outcomes were similar between YE and TE. However, TE demonstrated a greater improvement in knee flexor strength compared to YE (mean difference of 0.1 [95% CI, 0.1 to 0.2]. Improvements from baseline to follow-up were present in quality of life score for YE and knee flexor strength for TE, while both also demonstrated improvements in mobility. No improvement in any outcome was present in NE. Conclusions The biomechanically-based yoga exercise program produced clinically meaningful improvements in pain, self-reported physical function and mobility in women with clinical knee OA compared to no exercise. While not statistically significant, improvements in these outcomes were larger than those elicited from the traditional exercise-based program. Though this may suggest that the yoga program may be more efficacious for knee OA, future research studying a larger sample is required. Trial registration ClinicalTrials.gov (NCT02370667)