Michael A. Hunt

Validation of the Fitbit One activity monitor device during treadmill walking

OBJECTIVES In order to quantify the effects of physical activity such as walking on chronic disease, accurate measurement of physical activity is needed. The objective of this study was to determine the validity and reliability of a new activity monitor, the Fitbit One, in a population of healthy adults. DESIGN Cross-sectional study. METHODS Thirty healthy adults ambulated at 5 different speeds (0.90, 1.12, 1.33, 1.54, 1.78 m/s) on a treadmill while wearing three Fitbit One activity monitors (two on the hips and one in the pocket). The order of each speed condition was randomized. Fitbit One step count output was compared to observer counts and distance output was compared to the calibrated treadmill output. Two-way repeated measures ANOVA, concordance correlation coefficients, and Bland and Altman plots were used to assess validity and intra-class correlation coefficients (ICC) were used to assess reliability. RESULTS No significant differences were noted between Fitbit One step count outputs and observer counts, and concordance was substantial (0.97-1.00). Inter-device reliability of the step count was high for all walking speeds (ICC ≥ 0.95). Percent relative error was less than 1.3%. The distance output of the Fitbit One activity monitors was significantly different from the criterion values for each monitor at all speeds (P<0.001) and exhibited poor concordance (0.0-0.05). Inter-device reliability was excellent for all treadmill speeds (ICC ≥ 0.90). Percent relative error was high (up to 39.6%). CONCLUSIONS The Fitbit One activity monitors are valid and reliable devices for measuring step counts in healthy young adults. The distance output of the monitors is inaccurate and should be noted with caution.

Hip strengthening reduces symptoms but not knee load in people with medial knee osteoarthritis and varus malalignment: a randomised controlled trial

OBJECTIVE To determine whether hip abductor and adductor muscle strengthening reduces medial compartment knee load and improves symptoms in people with medial tibiofemoral OA and varus malalignment. METHODS In a randomised controlled trial, 89 participants were randomly allocated to a hip strengthening group or to a control group with no intervention. The strengthening group performed a physiotherapist-supervised home exercise program targeting the hip abductor and adductor muscles for 12 weeks. The primary outcome was the peak external knee adduction moment measured using three-dimensional gait analysis by a blinded assessor. Secondary outcomes included a pain numeric rating scale, Western Ontario and McMaster Universities Osteoarthritis Index, step test, stair climb test, maximum isometric strength of hip and quadriceps muscles and participant-perceived rating of overall change. Intention-to-treat analyses were performed using linear regression modelling adjusting for baseline outcomes and other characteristics. RESULTS The trial was completed by 76/89 participants (85%). There was no significant between-group difference in change in the knee adduction moment [mean difference (95% confidence interval (CI)) 0.134 (-0.069 to 0.337) Nm/BW x HT%]. All pain, physical function and muscle strength measures showed significantly greater improvement in the strengthening group (all P<0.05). The relative risk (95% CI) of participant-perceived overall improvement in the strengthening group compared to the control group was 20.02 (6.21-64.47). CONCLUSIONS Although strengthening the hip muscles improved symptoms and function in this patient group, it did not affect medial knee load as measured by the knee adduction moment. Thus it is unlikely that hip muscle strengthening influences structural disease progression. TRIAL REGISTRATION ACTR12607000001493.

Gait Modification Strategies for Altering Medial Knee Joint Load: A Systematic Review

To evaluate the effect of gait modification strategies on the external knee adduction moment (KAM), a marker of medial knee joint load; determine potentially adverse effects; assess the methodologic quality; and identify areas of future research.

Role of Muscle in the Genesis and Management of Knee Osteoarthritis

The muscles of the lower limb play an important role in the genesis and management of knee osteoarthritis (OA). This article outlines the influence of muscle activity on knee joint loading, the deficits in muscle function observed in people who have knee OA, and available evidence pertaining to the role of muscle in the development and progression of knee OA. It also discusses whether muscle deficits can be modified in knee OA and whether improvements in muscle function lead to improved symptoms and joint structure. It concludes with a discussion of exercise prescription for muscle rehabilitation in knee OA.

Quantified self and human movement: A review on the clinical impact of wearable sensing and feedback for gait analysis and intervention

The proliferation of miniaturized electronics has fueled a shift toward wearable sensors and feedback devices for the mass population. Quantified self and other similar movements involving wearable systems have gained recent interest. However, it is unclear what the clinical impact of these enabling technologies is on human gait. The purpose of this review is to assess clinical applications of wearable sensing and feedback for human gait and to identify areas of future research. Four electronic databases were searched to find articles employing wearable sensing or feedback for movements of the foot, ankle, shank, thigh, hip, pelvis, and trunk during gait. We retrieved 76 articles that met the inclusion criteria and identified four common clinical applications: (1) identifying movement disorders, (2) assessing surgical outcomes, (3) improving walking stability, and (4) reducing joint loading. Characteristics of knee and trunk motion were the most frequent gait parameters for both wearable sensing and wearable feedback. Most articles performed testing on healthy subjects, and the most prevalent patient populations were osteoarthritis, vestibular loss, Parkinsons disease, and post-stroke hemiplegia. The most widely used wearable sensors were inertial measurement units (accelerometer and gyroscope packaged together) and goniometers. Haptic (touch) and auditory were the most common feedback sensations. This review highlights the current state of the literature and demonstrates substantial potential clinical benefits of wearable sensing and feedback. Future research should focus on wearable sensing and feedback in patient populations, in natural human environments outside the laboratory such as at home or work, and on continuous, long-term monitoring and intervention.

Validity and inter-rater reliability of medio-lateral knee motion observed during a single-limb mini squat

BackgroundMuscle function may influence the risk of knee injury and outcomes following injury. Clinical tests, such as a single-limb mini squat, resemble conditions of daily life and are easy to administer. Fewer squats per 30 seconds indicate poorer function. However, the quality of movement, such as the medio-lateral knee motion may also be important. The aim was to validate an observational clinical test of assessing the medio-lateral knee motion, using a three-dimensional (3-D) motion analysis system. In addition, the inter-rater reliability was evaluated.MethodsTwenty-five (17 women) non-injured participants (mean age 25.6 years, range 18-37) were included. Visual analysis of the medio-lateral knee motion, scored as knee-over-foot or knee-medial-to-foot by two raters, and 3-D kinematic data were collected simultaneously during a single-limb mini squat. Frontal plane 2-D peak tibial, thigh, and knee varus-valgus angles, and 3-D peak hip internal-external rotation, and knee varus-valgus angles were calculated.ResultsTen subjects were scored as having a knee-medial-to-foot position and 15 subjects a knee-over-foot position assessed by visual inspection. In 2-D, the peak tibial angle (mean 89.0 (SE 0.7) vs mean 86.3 (SE 0.4) degrees, p = 0.001) and peak thigh angle (mean 77.4 (SE 1.0) vs mean 81.2 (SE 0.5) degrees, p = 0.001) with respect to the horizontal, indicated that the knee was more medially placed than the ankle and thigh, respectively. Thus, the knee was in more valgus (mean 11.6 (SE 1.5) vs 5.0 (SE 0.8) degrees, p < 0.001) in subjects with the knee-medial-to-foot than in those with a knee-over-foot position. In 3-D, the hip was more internally rotated in those with a knee-medial-to-foot than in those with a knee-over-foot position (mean 10.6 (SE 2.1) vs 4.8 (SE 1.8) degrees, p = 0.049), but there was no difference in knee valgus (mean 6.1 (SE 1.8) vs mean 5.0 (SE 1.2) degrees, p = 0.589). The kappa value and percent agreement, respectively, was >0.90 and 96 between raters.ConclusionsMedio-lateral motion of the knee can reliably be assessed during a single-leg mini-squat. The test is valid in 2-D, while the actual movement, in 3-D, is mainly exhibited as increased internal hip rotation. The single-limb mini squat is feasible and easy to administer in the clinical setting and in research to address lower extremity movement quality.

Feasibility of a gait retraining strategy for reducing knee joint loading: Increased trunk lean guided by real-time biofeedback

The purpose of this feasibility study was to examine changes in frontal plane knee and hip walking biomechanics following a gait retraining strategy focused on increasing lateral trunk lean and to quantify reports of difficulty and joint discomfort when performing such a gait modification. After undergoing a baseline analysis of normal walking, 9 young, healthy participants were trained to modify their gait to exhibit small (4°), medium (8°), and large (12°) amounts of lateral trunk lean. Training was guided by the use of real-time biofeedback of the actual trunk lean angle. Peak frontal plane external knee and hip joint moments were compared across conditions. Participants were asked to report the degree of difficulty and the presence of any joint discomfort for each amount of trunk lean modification. Small (4°), medium (8°), and large (12°) amounts of lateral trunk lean reduced the peak external knee adduction moment (KAM) by 7%, 21%, and 25%, respectively, though the peak KAM was only significantly less in the medium and large conditions (p<0.001). Increased trunk lean also significantly reduced the peak external hip adduction moments (p<0.001). All participants reported at least some difficulty performing the exaggerated trunk lean pattern and three participants reported ipsilateral knee, hip, and/or lower spine discomfort. Results from this study indicate that a gait pattern with increased lateral trunk lean can effectively reduce frontal plane joint moments. Though these findings have implications for pathological populations, learning this gait pattern was associated with some difficulty and joint discomfort.

Hip muscle weakness in individuals with medial knee osteoarthritis.

To compare the strength of the hip musculature in people with symptomatic medial knee osteoarthritis (OA) with asymptomatic controls.

Validity of the Microsoft Kinect for providing lateral trunk lean feedback during gait retraining

Gait retraining programs are prescribed to assist in the rehabilitation process of many clinical conditions. Using lateral trunk lean modification as the model, the aim of this study was to assess the concurrent validity of kinematic data recorded using a marker-based 3D motion analysis (3DMA) system and a low-cost alternative, the Microsoft Kinect™ (Kinect), during a gait retraining session. Twenty healthy adults were trained to modify their gait to obtain a lateral trunk lean angle of 10°. Real-time biofeedback of the lateral trunk lean angle was provided on a computer screen in front of the subject using data extracted from the Kinect skeletal tracking algorithm. Marker coordinate data were concurrently recorded using the 3DMA system, and the similarity and equivalency of the trunk lean angle data from each system were compared. The lateral trunk lean angle data obtained from the Kinect system without any form of calibration resulted in errors of a high (>2°) magnitude (mean error=3.2±2.2°). Performing global and individualized calibration significantly (P<0.001) improved this error to 1.7±1.5° and 0.8±0.8° respectively. With the addition of a simple calibration the anatomical position coordinates of the Kinect can be used to create a real-time biofeedback system for gait retraining. Given that this system is low-cost, portable and does not require any sensors to be attached to the body, it could provide numerous advantages when compared to laboratory-based gait retraining systems.

Update on the Role of Muscle in the Genesis and Management of Knee Osteoarthritis

This updated review outlines the influence of muscle activity on knee joint loading, describes the deficits in muscle function observed in people with knee osteoarthritis, and summarizes available evidence pertaining to the role of muscle in the development and progression of knee osteoarthritis. The review also focuses on whether muscle deficits can be modified in knee osteoarthritis and whether improvements in muscle function lead to improved symptoms and joint structure. The review concludes with a discussion of exercise prescription for muscle rehabilitation in knee osteoarthritis.