John Barden

Evaluation of age-related differences in the stride-to-stride fluctuations, regularity and symmetry of gait using a waist-mounted tri-axial accelerometer

PURPOSE To compare the stride-to-stride fluctuations, regularity and symmetry of gait using a body-fixed accelerometer in a group of healthy young and healthy older adults. METHODS Forty-one healthy young adults (24 ± 3 years) and forty-one healthy older adults (76 ± 5 years) completed a 10-min walk at a self-selected, normal walking speed while wearing a single waist-mounted tri-axial accelerometer. The following gait parameters were compared between age groups: mean step and stride time, step and stride time variability, stride time fractal scaling index and the regularity and symmetry of the acceleration pattern in the vertical, mediolateral and anteroposterior directions (unbiased autocorrelation procedure). RESULTS Older adults displayed significantly greater step and stride time variability (p<0.05) and a lower stride time fractal scaling index (p<0.01), as well as significantly less regularity (p<0.05) and symmetry (p<0.05) of the anteroposterior accelerations. CONCLUSION The results show that healthy older adults possess greater temporal gait variability, as well as a less-organized and repeatable pattern of variability and acceleration in the direction of motion, than younger adults. The findings also suggest the presence of an age-related decline in the anteroposterior control of gait, but not in the vertical and mediolateral control of gait.

The Relationship of Fear of Falling and Balance Confidence With Balance and Dual Tasking Performance

According to traditional conceptualizations of the relationship between fear of falling and falls in older adults, fear of falling is considered to be predictive of falls because it leads to activity avoidance which, in turn, leads to de-conditioning that increases fall risk. The recent literature has begun to challenge such conceptualizations. Specifically, it has been argued that fear of falling and anxiety, in and of themselves, have a direct negative effect on balance. In this study we manipulated anxiety level by asking older research participants to walk either on the floor (low anxiety condition) or an elevated platform (high anxiety condition). Half the time participants carried a tray (dual tasking) and half the time they did not. Manipulation checks (involving heart rate, galvanic skin response, and self-reported anxiety measurement) confirmed that the experimental manipulation was successful in affecting anxiety level. The results demonstrate that the experimental manipulation (platform vs. floor) affected balance parameters and dual tasking performance with the platform condition resulting in a less stable gait. In addition, increased task demand (i.e., dual tasking) also had a negative effect on balance performance. Finally, the results demonstrate that the paper and pencil measures of fear can also predict balance performance (although the variance accounted for is small) even after controlling for medical risk factors for falling. Implications for models of fear of falling are discussed.

Contributions of trunk muscles to anticipatory postural control in children with and without developmental coordination disorder

Current evidence suggests that movement quality is impacted by postural adjustments made in advance of planned movement. The trunk inevitably plays a key role in these adjustments, by creating a stable foundation for limb movement. The purpose of this study was to examine anticipatory trunk muscle activity during functional tasks in children with and without developmental coordination disorder (DCD). Eleven children with DCD (age 7 to 14 years) and 11 age-matched, typically-developing children performed three tasks: kicking a ball, climbing stairs, and single leg balance. Surface electromyography (EMG) was used to examine the neuromuscular activity of bilateral transversus abdominis/internal oblique, external oblique and L3/4 erector spinae, as well as the right tibialis anterior and rectus femoris muscles. Onset latencies for each muscle were calculated relative to the onset of rectus femoris activity. In comparison to the children with DCD, the typically-developing children demonstrated earlier onsets for right tibialis anterior, bilateral external oblique, and right transversus abdominis/internal oblique muscles. These results suggest that anticipatory postural adjustments may be associated with movement problems in children with DCD, and that timing of both proximal and distal muscles should be considered when designing intervention programs for children with DCD.

The response of persons with chronic nonspecific low back pain to three different volumes of periodized musculoskeletal rehabilitation.

Kell, RT, Risi, AD, and Barden, JM. The response of persons with chronic nonspecific low back pain to three different volumes of periodized musculoskeletal rehabilitation. J Strength Cond Res 25(4): 1052-1064, 2011-Chronic nonspecific low back pain (CLBP) is a common musculoskeletal health issue associated with pain and disability reduced quality of life (QoL). Pain initiates a fear-avoidance cycle, which needs to be broken if rehabilitation is to work. To break this cycle, exercise must be gradual and focused on strengthening the weakened musculature. Recently, periodized resistance training was effectively used as a musculoskeletal rehabilitation for adults with CLBP. The purpose of this study was to determine if the volume of periodized musculoskeletal rehabilitation (PMR) influences strength, pain, disability, and QoL in untrained persons. Subjects (n = 240) were age and sex matched, with attempts made to match on strength and pain, and randomly assigned to groups after baseline testing: (a) 4 days per week (4D; n = 60), (b) 3 days per week (3D; n = 60) (c), 2 days per week (2D; n = 60) training volume or control (C; n = 60) with no training. The PMR program progressively overloaded muscle groups, with mean training volumes of 4D (1,563 repetitions [reps] per week), 3D (1,344 reps per week), and 2D (564 reps per week). Three weeks of familiarization and 13 weeks of PMR were employed. The 4D training volume significantly (p ≤ 0.05) outperformed all other training volumes by weeks 9 and 13. However, all training volumes made significant (p ≤ 0.05) improvements in strength, pain, disability, and QoL across time. The effect sizes (ESs) associated with the group means of the outcome measures ranged from moderate to strong, with the 4D training volume consistently demonstrating the largest ESs. The 4D training volume is most effective at treating CLBP. Periodization cannot only be applied to athlete training but also to the rehabilitation setting.

Relationships between stroke parameters and critical swimming speed in a sprint interval training set

Abstract The aim of this study was to determine whether a relationship exists between stroke parameters and critical swimming speed (which is defined as the speed that can theoretically be maintained without exhaustion). Stroke parameters (stroke rate and length) and velocity were recorded for each 25-m length during a controlled sprint interval training set in which participants swam one of the four competitive strokes at a range of intensities below, at, and above critical speed. Eleven participants (8 females, 3 males; age 17.9 ± 0.9 years) completed a progressive (descending) set of 8 × 100 m repetitions in a 25-m pool according to target times that ranged in intensity from 65% to 100% of the swimmers best time (the intensity for each repetition increased by 5% throughout the set). The data showed that participants reached critical speed on the fourth repetition and that substantial and unpredictable changes in stroke parameters occurred once critical speed had been reached. Specifically, post-critical speed stroke rate and stroke length were significantly (P < 0.01) greater and less, respectively, than the pre-critical speed values, and these changes occurred in an abrupt and non-linear manner. Overall, the findings suggest that critical speed represents a transition point between two different sets of stroke parameter relationships – one for low-intensity aerobic swimming and one for high-intensity anaerobic swimming.

The effect of critical speed and exercise intensity on stroke phase duration and bilateral asymmetry in 200-m front crawl swimming

Abstract The main aim of this study was to determine the absolute temporal relationship between the power and recovery phases of the stroke cycle in front crawl swimming in response to progressive changes in exercise intensity that occurred before and after critical speed. A second objective was to determine whether intensity-related changes in the power/recovery phase relationship affects the bilateral symmetry of the stroke. Stroke parameters were recorded for each 25-m length during a progressive 200-m interval training set, in which eight (2 males, 6 females) national-level swimmers swam at intensities below, above, and at critical speed. The results demonstrated that substantial increases in stroke rate (P < 0.01) occurred at critical speed, and that these increases were related to a greater decrease in the duration of the power phase than the recovery phase (P < 0.01). The results also show that the degree of bilateral asymmetry was greater for the power phase than the recovery phase, and was inversely related to intensity in both phases of the stroke cycle. The findings of this study suggest that critical speed-related increases in stroke rate are an indirect consequence of increased force production in the power phase of the stroke, and that bilateral asymmetry is both intensity- and stroke-phase dependent.

Frequency of anticipatory trunk muscle onsets in children with and without developmental coordination disorder.

ABSTRACT This study used electromyography to compare the frequency of anticipatory postural adjustments for three bilateral trunk muscles and unilateral tibialis anterior muscle between children with and without developmental coordination disorder (DCD; n = 22, ages 7 to 14 years) during three tasks (kicking a ball, stepping onto a step, standing on one foot). Between-group comparisons demonstrated significantly less frequent anticipatory activation of ipsilateral tibialis anterior, ipsilateral transversus abdominis/internal oblique, and bilateral external oblique muscles in children with DCD. Odds ratios indicated that children with DCD utilized anticipatory contractions of these muscles one half to one quarter as often as the typically developing children did, while performing the same tasks. These results suggest that the movement difficulties experienced by children with DCD may be associated with less frequent anticipatory adjustments. For these children, inconsistent preparatory activation may contribute to postural control difficulties, excessive movement variability and poor movement quality.

Guidelines for Assessment of Gait and Reference Values for Spatiotemporal Gait Parameters in Older Adults: The Biomathics and Canadian Gait Consortiums Initiative

Background: Gait disorders, a highly prevalent condition in older adults, are associated with several adverse health consequences. Gait analysis allows qualitative and quantitative assessments of gait that improves the understanding of mechanisms of gait disorders and the choice of interventions. This manuscript aims (1) to give consensus guidance for clinical and spatiotemporal gait analysis based on the recorded footfalls in older adults aged 65 years and over, and (2) to provide reference values for spatiotemporal gait parameters based on the recorded footfalls in healthy older adults free of cognitive impairment and multi-morbidities. Methods: International experts working in a network of two different consortiums (i.e., Biomathics and Canadian Gait Consortium) participated in this initiative. First, they identified items of standardized information following the usual procedure of formulation of consensus findings. Second, they merged databases including spatiotemporal gait assessments with GAITRite® system and clinical information from the “Gait, cOgnitiOn & Decline” (GOOD) initiative and the Generation 100 (Gen 100) study. Only healthy—free of cognitive impairment and multi-morbidities (i.e., ≤ 3 therapeutics taken daily)—participants aged 65 and older were selected. Age, sex, body mass index, mean values, and coefficients of variation (CoV) of gait parameters were used for the analyses. Results: Standardized systematic assessment of three categories of items, which were demographics and clinical information, and gait characteristics (clinical and spatiotemporal gait analysis based on the recorded footfalls), were selected for the proposed guidelines. Two complementary sets of items were distinguished: a minimal data set and a full data set. In addition, a total of 954 participants (mean age 72.8 ± 4.8 years, 45.8% women) were recruited to establish the reference values. Performance of spatiotemporal gait parameters based on the recorded footfalls declined with increasing age (mean values and CoV) and demonstrated sex differences (mean values). Conclusions: Based on an international multicenter collaboration, we propose consensus guidelines for gait assessment and spatiotemporal gait analysis based on the recorded footfalls, and reference values for healthy older adults.

Accelerometer-based determination of gait variability in older adults with knee osteoarthritis

Knee osteoarthritis (KOA) can affect the spatiotemporal (ST) aspects of gait as well as the variability of select ST parameters based on standard linear measures of variability (e.g., standard deviation (SD) and coefficient of variation). Non-linear measures (e.g., fractal scaling index (FSI) and sample entropy) can be more sensitive to changes in gait variability, and have been used to quantify differences in the stride patterns of patients with Parkinsons disease and the motion of ACL-deficient knees. However, the effect of KOA on the dynamic complexity of the stride pattern has not been investigated. Therefore, the purpose of this study was to investigate the effect of KOA on gait variability (linear and non-linear measures) in a group of older adults, and to compare these results to a healthy control group. Participants walked for 10min with a tri-axial accelerometer placed at the lower back. Mean and SDs of stride time and step time as well as the FSI for the entire series of stride times were calculated for each participant. Participants with KOA had significantly greater mean stride time (p=0.031) and step time (p=0.024) than control group participants. While stride and step time variability (SD) were greater in the KOA group, the differences were not significant, nor was the difference in the FSI. Low statistical power (β=0.40 and 0.30 for stride and step time SD, respectively) combined with the confounding effects of walking speed and heterogeneous KOA severity likely prevented significant differences from being found.

Accelerometer-Based Step Regularity Is Lower in Older Adults with Bilateral Knee Osteoarthritis

Purpose: To compare the regularity and symmetry of gait between a cohort of older adults with bilateral knee osteoarthritis (OA) and an age and sex-matched control group of older adults with healthy knees. Methods: Fifteen (8 females) older adults with knee OA (64.7 ± 6.7 years) and fifteen (8 females) pain-free controls (66.1 ± 10.0 years) completed a 9-min. walk at a self-selected, comfortable speed while wearing a single waist-mounted tri-axial accelerometer. The following gait parameters were compared between the two groups according to sex: mean step time, mean stride time, stride and step regularity (defined as the consistency of the stride-to-stride or step-to-step pattern) and the symmetry of gait (defined as the difference between step and stride regularity) as determined by an unbiased autocorrelation procedure that analyzed the pattern of acceleration in the vertical, mediolateral and anteroposterior directions. Results: Older adults with knee OA displayed significantly less step regularity in the vertical (p < 0.05) and anteroposterior (p < 0.05) directions than controls. Females with knee OA were also found to have significantly less mediolateral step regularity than female controls (p < 0.05), whereas no difference was found between males. Conclusion: The results showed that the regularity of the step pattern in individuals with bilateral knee OA was less consistent compared to similarly-aged older adults with healthy knees. The findings suggest that future studies should investigate the relationship between step regularity, sex and movement direction as well as the application of these methods to the clinical assessment of knee OA.