Aging, Visuomotor Correction, and Force Fluctuations in Large Muscles

Tracy, Brian; Dinenno, Devin V.; Jorgensen, Bjorn; Welsh, Seth J.

doi:10.1249/mss.0b013e31802d3ad3

Cited by 93 publications

(156 citation statements)

References 38 publications

(82 reference statements)

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“…The amplitude of force fluctuation, an index of force stability, is also inversely related to the level of effort and to the number of the recruited motor units (Hamilton et al 2004), and has been shown to be influenced directly by alterations in synergistic muscle activation (Shinohara et al 2009). Overall, visual feedback removal during an isometric task either did not influence (Christou et al 2004;Vaillancourt and Russell 2002) or reduce force variability /accuracy making more stable the signal Christou 2005;Tracy et al 2007;Baweja et al 2009;Kennedy and Christou 2011;Schiffman et al 2002;Tracy 2007b). Conversely, Moreover, when visual feedback is removed, the force accuracy was compromised because the force output tended to drift away from the required target (Tracy 2007b;Vaillancourt and Russell 2002).…”

Section: Donementioning

confidence: 93%

“…This phenomenon became more evident as force level increased (Baweja et al 2009). Vaillancourt and Russell (2002) and Tracy et al (2007) reported that the direction of force drift depends on the level of force intensity. In particular, when visual feedback was removed, force output tended to overshoot the target at low force levels, and to undershoot the target at high force levels Vaillancourt and Russell 2002).…”

Section: Effect Of Visual Feedback (Nofb-1 Vs Fb )mentioning

confidence: 99%

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Effects of visual feedback absence on force control during isometric contraction

et al. 2014

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Section: Donementioning

confidence: 93%

Section: Effect Of Visual Feedback (Nofb-1 Vs Fb )mentioning

confidence: 99%

Effects of visual feedback absence on force control during isometric contraction

et al. 2014

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“…The order of these target forces was randomized. Participants maintained a knee extension force as steady as possible for 15 s (Clark et al 2007;Tracy et al 2007). Each recording task was completed within 10 min of the cessation of vibration.…”

Section: Knee Extension Taskmentioning

confidence: 99%

“…Therefore, the force steadiness of the QF during steady contraction would offer additional information about postural stability and locomotion (Tracy and Enoka 2002;Tracy et al 2007;Krishnan et al 2011). Prolonged vibration of the patellar tendon decreases H-reflex amplitude in the vastus medialis (VM) (Fry and Folland 2014), which suggests that the vibration intervention influences the pathway from the Ia afferents to α-motor neurons.…”

Section: Introductionmentioning

confidence: 99%

Effects of prolonged patellar tendon vibration on force steadiness in quadriceps femoris during force-matching task

2015

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The quadriceps femoris (QF) muscle group plays an essential role in human movement, such as standing, walking and running. The ability to maintain a steady force during physical activity of the human lower limb is important for mobility, postural control and balance. Although prolonged mechanical vibration of the muscle-tendon unit can moderate the efficacy of synaptic input from Ia afferent onto the α-motor neuron pathway, the effect of prolonged tendon vibration on fluctuations of knee extensor force has received little attention. The purpose of the present study was to examine the effects of prolonged patellar tendon vibration on the force steadiness of the QF muscle. Nine healthy men performed a submaximal force-matching task involving isometric knee extension before and after patellar tendon vibration or quiet seated rest (n = 7, control condition) for 30 min. The target force was 2.5, 10 and 30 % of maximal voluntary contraction (MVC). Surface electromyography (EMG) of the four QF synergists was recorded and normalized to EMG amplitude during the MVC. The knee extension force and the EMG amplitude of vastus medialis during the MVC were significantly reduced after the vibration, but did not significantly decrease in the control condition. Fluctuations of force and normalized EMG of individual QF muscles at each submaximal force level did not significantly change after the vibration. We conclude that prolonged patellar tendon vibration does not influence the force steadiness of the QF muscle during an isometric force-matching task.

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“…Some studies indicate that removing feedback has no effect (Vaillancourt and Russell 2002;Taylor et al 2003;Christou et al 2004;Christou 2005), whereas other studies report that force tremor is reduced (Tracy 2007;Tracy et al 2007;Baweja et al 2009;Marmon et al 2011) or even increased in the absence of feedback (Slifkin et al 2000;Sosnoff and Newell 2005). However, no study has examined the influence that visual targeting has on force tremor in a bilateral context.…”

Section: Introductionmentioning

confidence: 99%

Removing visual feedback for a single limb alters between-limb force tremor relationships during isometric bilateral contractions

2014

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This study examined how force tremor and muscle activity are altered between limbs when a visual target is removed for one limb during bilateral index finger abduction. Isometric index finger abduction force was examined in healthy adults (23 ± 4 years) when both index fingers abducted simultaneously. Abduction forces ranged from 5 to 20% maximum voluntary contraction, and these target forces were displayed on a PC monitor in front of the subject. Force tremor and first dorsal interosseous (FDI) activity were first collected while subjects viewed visual targets for both index fingers and then when the visual target was removed for the non-dominant index finger. Subjects successfully matched the force amplitudes generated for both limbs regardless of visual condition. When the visual target was removed for one limb, force tremor increased in this limb (p < 0.01). Different power spectral profiles were evident for each FDI EMG when targets were available for both limbs (p < 0.05); however, when one target was removed, the pattern of FDI EMG for the limb without a visual target closely reflected FDI EMG for the limb which had the visual target. The CNS actively modulates muscle activity in each limb to perform visually guided isometric contractions. Given that the goal was to match force output with both limbs, the requirements of the task must be established from the limb that had a visual target, and a copy of those motor commands appears to have been sent to the FDI of the limb without a visual target.

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Aging, Visuomotor Correction, and Force Fluctuations in Large Muscles

Abstract: Visuomotor correction contributed to force fluctuations in large proximal muscles. The contribution was greater for healthy elderly adults at low forces. Visuomotor processes thus contributed to the age-related increase in force fluctuations.

Cited by 93 publications

References 38 publications

Effects of visual feedback absence on force control during isometric contraction

Effects of visual feedback absence on force control during isometric contraction

Effects of prolonged patellar tendon vibration on force steadiness in quadriceps femoris during force-matching task

Removing visual feedback for a single limb alters between-limb force tremor relationships during isometric bilateral contractions

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