Stroke-Related Changes in Neuromuscular Fatigue of the Hip Flexors and Functional Implications

Hyngstrom, Allison S.; Onushko, Tanya; Rutkowski, Anthony M.; Hunter, Sandra K.; Schmit, Brian D.

doi:10.1097/phm.0b013e31823caac0

Cited by 24 publications

(32 citation statements)

References 26 publications

(34 reference statements)

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“…In the current study, fluctuations in force magnitude were maximal when older adults pressed at the 2.5% peak F z level with visual feedback against the Teflon surface (Figure 3). Indeed, CV of force for this condition was 12.3±9.9%, which is more similar to that reported for stroke patients during fatiguing contractions [15] than healthy older adults where values typically range from 4–8% at low force levels [10], [11]. Although the CV of force is generally greatest at low forces [11], [13], especially when visual feedback is provided [13], force variability may have further increased in older adults pressing against Teflon due to: 1) an inability to stabilize the position of the finger and control variability in tangential directions to the normal force to avoid slipping and 2) impaired sensation.…”

Section: Discussionsupporting

confidence: 87%

Control of Fingertip Forces in Young and Older Adults Pressing against Fixed Low- and High-Friction Surfaces

Keenan

Massey

2012

PLoS ONE

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Mobile computing devices (e.g., smartphones and tablets) that have low-friction surfaces require well-directed fingertip forces of sufficient and precise magnitudes for proper use. Although general impairments in manual dexterity are well-documented in older adults, it is unclear how these sensorimotor impairments influence the ability of older adults to dexterously manipulate fixed, low-friction surfaces in particular. 21 young and 18 older (65+ yrs) adults produced maximal voluntary contractions (MVCs) and steady submaximal forces (2.5 and 10% MVC) with the fingertip of the index finger. A Teflon covered custom-molded splint was placed on the fingertip. A three-axis force sensor was covered with either Teflon or sandpaper to create low- and high-friction surfaces, respectively. Maximal downward forces (Fz) were similar (p = .135) for young and older adults, and decreased by 15% (p<.001) while pressing on Teflon compared to sandpaper. Fluctuations in Fz during the submaximal force-matching tasks were 2.45× greater (p<.001) for older adults than in young adults, and reached a maximum when older adults pressed against the Teflon surface while receiving visual feedback. These age-associated changes in motor performance are explained, in part, by altered muscle activity from three hand muscles and out-of-plane forces. Quantifying the ability to produce steady fingertip forces against low-friction surfaces may be a better indicator of impairment and disability than the current practice of evaluating maximal forces with pinch meters. These age-associated impairments in dexterity while interacting with low-friction surfaces may limit the use of the current generation of computing interfaces by older adults.

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Section: Discussionsupporting

confidence: 87%

Control of Fingertip Forces in Young and Older Adults Pressing against Fixed Low- and High-Friction Surfaces

Keenan

Massey

2012

PLoS ONE

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“…Similar results were found in patients with neurological disorders [30]. It was argued that the changes observed may be associated with both mechanisms of cardiorespiratory and muscle fatigue which influence performance [31]. These results suggest that fatigue could occur during a gait analysis session, influencing the results, particularly at the end of the recording session.…”

Section: Introductionsupporting

confidence: 77%

Variations in Kinematics during Clinical Gait Analysis in Stroke Patients

Boudarham¹,

Roche²,

Pradon³

et al. 2013

PLoS ONE

111

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In addition to changes in spatio-temporal and kinematic parameters, patients with stroke exhibit fear of falling as well as fatigability during gait. These changes could compromise interpretation of data from gait analysis. The aim of this study was to determine if the gait of hemiplegic patients changes significantly over successive gait trials. Forty two stroke patients and twenty healthy subjects performed 9 gait trials during a gait analysis session. The mean and variability of spatio-temporal and kinematic joint parameters were analyzed during 3 groups of consecutive gait trials (1–3, 4–6 and 7–9). Principal component analysis was used to reduce the number of variables from the joint kinematic waveforms and to identify the parts of the gait cycle which changed during the gait analysis session. The results showed that i) spontaneous gait velocity and the other spatio-temporal parameters significantly increased, and ii) gait variability decreased, over the last 6 gait trials compared to the first 3, for hemiplegic patients but not healthy subjects. Principal component analysis revealed changes in the sagittal waveforms of the hip, knee and ankle for hemiplegic patients after the first 3 gait trials. These results suggest that at the beginning of the gait analysis session, stroke patients exhibited phase of adaptation,characterized by a “cautious gait” but no fatigue was observed.

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“…The age-associated differences in force control occur primarily at very low-force levels [2], [11] and are functionally relevant for many activities of daily living (e.g. writing, buttoning a shirt, manipulating objects) [12], [13]. In this study we focused on low-frequency oscillations in force because they have been associated with impaired submaximal force control in older adults.…”

Section: Introductionmentioning

confidence: 99%

Modulation of Force below 1 Hz: Age-Associated Differences and the Effect of Magnified Visual Feedback

et al. 2013

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Oscillations in force output change in specific frequency bins and have important implications for understanding aging and pathological motor control. Although previous studies have demonstrated that oscillations from 0–1 Hz can be influenced by aging and visuomotor processing, these studies have averaged power within this bandwidth and not examined power in specific frequencies below 1 Hz. The purpose was to determine whether a differential modulation of force below 1 Hz contributes to changes in force control related to manipulation of visual feedback and aging. Ten young adults (25±4 yrs, 5 men) and ten older adults (71±5 yrs, 4 men) were instructed to accurately match a target force at 2% of their maximal isometric force for 35 s with abduction of the index finger. Visual feedback was manipulated by changing the visual angle (0.05°, 0.5°, 1.5°) or removing it after 15 s. Modulation of force below 1 Hz was quantified by examining the absolute and normalized power in seven frequency bins. Removal of visual feedback increased normalized power from 0–0.33 Hz and decreased normalized power from 0.66–1.0 Hz. In contrast, magnification of visual feedback (visual angles of 0.5° and 1.5°) decreased normalized power from 0–0.16 Hz and increased normalized power from 0.66–1.0 Hz. Older adults demonstrated a greater increase in the variability of force with magnification of visual feedback compared with young adults (P = 0.05). Furthermore, older adults exhibited differential force modulation of frequencies below 1 Hz compared with young adults (P<0.05). Specifically, older adults exhibited greater normalized power from 0–0.16 Hz and lesser normalized power from 0.66–0.83 Hz. The changes in force modulation predicted the changes in the variability of force with magnification of visual feedback (R2 = 0.80). Our findings indicate that force oscillations below 1 Hz are associated with force control and are modified by aging and visual feedback.

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Stroke-Related Changes in Neuromuscular Fatigue of the Hip Flexors and Functional Implications

Cited by 24 publications

References 26 publications

Control of Fingertip Forces in Young and Older Adults Pressing against Fixed Low- and High-Friction Surfaces

Control of Fingertip Forces in Young and Older Adults Pressing against Fixed Low- and High-Friction Surfaces

Variations in Kinematics during Clinical Gait Analysis in Stroke Patients

Modulation of Force below 1 Hz: Age-Associated Differences and the Effect of Magnified Visual Feedback

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