Paraspinal muscle responses during sudden upper limb loading

Cervical transcutaneous spinal cord stimulation (tSCS) efficacy for rehabilitation of upper-limb motor function was suggested to depend on recruitment of Ia afferents. However, selectivity and excitability of motor activation with different electrode configurations remains unclear. In this study, activation of upper-limb motor pools was examined with different cathode and anode configurations during cervical tSCS in 10 able-bodied individuals. Muscle responses were measured from six upper-limb muscles simultaneously. First, post-activation depression was confirmed with tSCS paired pulses (50 ms interval) for each cathode configuration (C6, C7, and T1 vertebral levels), with anode on the anterior neck. Selectivity and excitability of activation of the upper-limb motor pools were examined by comparing the recruitment curves (10-100 mA) of first evoked responses across muscles and cathode configurations. Our results showed that hand muscles were preferentially activated when the cathode was placed over T1 compared to the other vertebral levels, while there was no selectivity for proximal arm muscles. Furthermore, higher stimulation intensities were required to activate distal hand muscles than proximal arm muscles, suggesting different excitability thresholds between muscles. In a separate protocol, responses were compared between anode configurations (anterior neck, shoulders, iliac crests, and back), with one selected cathode configuration. The level of discomfort was also assessed. Largest muscle responses were elicited with the anode configuration over the anterior neck, while there were no differences in the discomfort. Our results therefore inform methodological considerations for electrode configuration to help optimize recruitment of Ia afferents during cervical tSCS.

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Technique effects on upper limb loading in the tennis serve

Journal of Science and Medicine in Sport ◽

10.1016/s1440-2440(03)80011-7 ◽

2003 ◽

Vol 6 (1) ◽

pp. 76-87 ◽

Cited By ~ 143

Author(s):

B Elliott ◽

G Fleisig ◽

R Nicholls ◽

R Escamilia

Keyword(s):

Upper Limb ◽

Limb Loading ◽

Tennis Serve

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Relationships between Upper Limb Loading, Physical Findings, and Discomfort Associated with Keyboard Use

Proceedings of the Human Factors and Ergonomics Society Annual Meeting ◽

10.1177/154193120104501421 ◽

2001 ◽

Vol 45 (14) ◽

pp. 1087-1091

Author(s):

Brian D. Lowe ◽

J. Steven Moore ◽

Naomi Swanson ◽

Lisa Perez ◽

Margit Alderson

Keyword(s):

Upper Limb ◽

Limb Loading ◽

Physical Findings

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Rapid and flexible whole body postural responses are evoked from perturbations to the upper limb during goal-directed reaching

Journal of Neurophysiology ◽

10.1152/jn.01004.2015 ◽

2017 ◽

Vol 117 (3) ◽

pp. 1070-1083 ◽

Cited By ~ 12

Author(s):

Catherine R. Lowrey ◽

Joseph Y. Nashed ◽

Stephen H. Scott

Keyword(s):

Upper Limb ◽

Lower Limb ◽

Muscle Activity ◽

Whole Body ◽

Limb Muscle ◽

Behavioral Context ◽

Body Balance ◽

Postural Responses ◽

Muscle Responses ◽

Behavioral Goal

An important aspect of motor control is the ability to perform tasks with the upper limbs while maintaining whole body balance. However, little is known about the coordination of upper limb voluntary and whole body postural control after mechanical disturbances that require both upper limb motor corrections to attain a behavioral goal and lower limb motor responses to maintain whole body balance. The present study identified the temporal organization of muscle responses and center of pressure (COP) changes following mechanical perturbations during reaching. Our results demonstrate that muscle responses in the upper limb are evoked first (∼50 ms), with lower limb muscle activity occurring immediately after, in as little as ∼60 ms after perturbation. Hand motion was immediately altered by the load, while COP changes occurred after ∼100 ms, when lower limb muscle activity was already present. Our secondary findings showed that both muscle activity and COP changes were influenced by behavioral context (by altering target shape, circle vs. rectangle). Voluntary and postural actions initially directed the hand toward the center of both target types, but after the perturbation upper limb and postural responses redirected the hand toward different spatial locations along the rectangle. Muscle activity was increased for both upper and lower limbs when correcting to the circle vs. the rectangle, and these differences emerged as early as the long-latency epoch (∼75–120 ms). Our results demonstrate that postural responses are rapidly and flexibly altered to consider the behavioral goal of the upper limb. NEW & NOTEWORTHY The present work establishes that, when reaching to a target while standing, perturbations applied to the upper limb elicit a rapid response in lower limb muscles. Unlike voluntary movements, postural responses do not occur before corrections of the upper limb. We show the first evidence that corrective postural adjustments are modulated by upper limb behavioral context (target shape). Importantly, this indicates that postural responses take into account upper limb feedback for online control.

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The utility of upper limb loading device in determining optimal walking ability in ambulatory individuals with spinal cord injury

Hong Kong Physiotherapy Journal ◽

10.1142/s1013702521500050 ◽

2021 ◽

pp. 1-9

Author(s):

Makamas Kumprou ◽

Pipatana Amatachaya ◽

Thanat Sooknuan ◽

Preeda Arayawichanon ◽

Thiwabhorn Thaweewannakij ◽

...

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Upper Limb ◽

Lower Limb ◽

Weight Bearing ◽

Walking Ability ◽

Limb Loading ◽

Cord Injury ◽

Loading Device ◽

Walking Performance

Background: Walking devices are frequently prescribed for many individuals, including those with spinal cord injury (SCI), to promote their independence. However, without proper screening and follow-up care, the individuals may continue using the same device when their conditions have progressed, that may possibly worsen their walking ability. Objective: This study developed an upper limb loading device (ULLD), and assessed the possibility of using the tool to determine the optimal walking ability of ambulatory participants with SCI who used a walking device daily ([Formula: see text]). Methods: All participants were assessed for their optimal walking ability, i.e., the ability of walking with the least support device or no device as they could do safely and confidently. The participants were also assessed for their amount of weight-bearing on the upper limbs or upper limb loading while walking, amount of weight-bearing on the lower limbs or lower limb loading while stepping of the other leg, and walking performance. Results: The findings indicated that approximately one third of the participants (31%) could progress their walking ability from their current ability, whereby four participants could even walk without a walking device. The amount of upper limb loading while walking, lower limb loading ability, and walking performance were significantly different among the groups of optimal walking ability ([Formula: see text]). Furthermore, the amount of upper limb loading showed negative correlation to the amount of lower limb loading and walking performance ([Formula: see text] to [Formula: see text]0.493, [Formula: see text]). Conclusion: The findings suggest the potential benefit of using the upper limb loading device and the amount of upper limb loading for walking device prescription, and monitoring the change of walking ability among ambulatory individuals with SCI.

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