Effects of a compression garment on sensory feedback transmission in the human upper limb

Abstract

Compression apparel is popular in both medical and sport performance settings. Perceived benefits are suggested to include changes in sensory feedback transmission caused by activation of mechanoreceptors. However, little is known about effects of compression apparel on sensorimotor control. Our purpose was to mechanistically examine whether compression apparel modulates sensory feedback transmission and reaching accuracy in the upper limb. Two experiments were completed under CONTROL and COMPRESSION (sleeve applied across the elbow joint) conditions. M-waves and H-reflexes were elicited by stimulating the median nerve and were recorded via surface electromyography (EMG). In experiment 1, H-reflexes and M-H recruitment curves were assessed at REST, during wrist flexion (10% EMG_max), and during a cutaneous conditioning of the superficial radial (SR) or distal median (MED) nerve. Cutaneous reflexes were elicited during 10% wrist flexion via stimulation of SR or MED. In experiment 2, unconditioned H-reflex measures were assessed at rest, during arm cycling, and during a discrete reaching task. Results indicate that compression apparel modulates spinal cord excitability across multiple sensory pathways and movement tasks. Interestingly, there was a significant improvement in reaching accuracy while wearing the compression sleeve. Taken together, the compression sleeve appears to increase precision and sensitivity around the joint where the sleeve is applied. Compression apparel may function as a "filter" of irrelevant mechanoreceptor information allowing for optimal task-related sensory information to enhance proprioception. NEW & NOTEWORTHY Wearing a customized compression sleeve was shown to alter the excitability of multiple pathways within the central nervous system regardless of conditioning input or movement task and was accompanied by improved accuracy of reaching movements and determination of movement end point. Compression apparel may assist as a type of "filter function" of tonic and nonspecific mechanoreceptor information leading to increased precision and movement sensitivity around the joint where compression is applied.

Keywords: H-reflex; afferent feedback; compression; conditioning; cutaneous; electromyography; proprioception.

Fig. 1.

A: experimental setup of experiment 1 without compression sleeve. B: experimental setup of experiment 1 with compression sleeve. Stimulation electrode (Stim) placement on the median nerve proximal to the elbow to elicit H-reflexes in the flexor carpi radialis is depicted in both setups. FCR, flexor carpi radialis.

Fig. 2.

Schematic of H-reflex and conditioning pathways. Schematic diagram outlining possible neural pathways for integration of inputs on Ia afferents arising from a compression sleeve placed around the elbow joint. FCR, flexor carpi radialis; INs, interneurons; MNs, motoneurons.

Fig. 3.

Movement tasks during experiment 2. Arm cycling was performed at a cadence of 1 Hz (60 rpm). The discrete reaching task was initiated at the 12 o’clock position and ended at 8 o’clock. Stimulation for both tasks was provided at the 3 (extension) and 6 o’clock (flexion) positions during separate trials.

Fig. 4.

Effects of conditioning paradigm. A: individual subject traces that show the effect of conditioning on H-reflex amplitude while M-wave is maintained constant. B: group average of maximally evoked M-wave (M_max) amplitude across the four conditions, with and without compression. C: group average of maximally evoked H-reflex (H_max) amplitude pooled between CONTROL and COMPRESSION across all participants. #Significantly lower H_max than all other conditions. *Significantly higher H_max than all other conditions. Values are means ± SE (P < 0.05). MED, distal median; SR, superficial radial; VOL, voluntary contraction.

Fig. 5.

Effects of compression sleeve during experiment 1. A: single subject traces of the average H-reflex amplitude during 10% contraction, SR nerve conditioning, and MED nerve conditioning. Solid traces indicate control averages, whereas dotted traces indicate inhibited compression averages. B: group average of M-wave amplitude across conditions indicating same input provided. C: group average of H-reflex amplitude with and without compression. *Significant reduction in H-reflex amplitude while wearing compression sleeve across all three conditions. Values are means ± SE (P < 0.05).

Fig. 6.

Effects of compression on long-latency cutaneous reflex amplitude. *Significant increase in long-latency cutaneous reflex amplitude while wearing the compression sleeve. Values are means ± SE (P < 0.05). MED, distal median; SR, superficial radial.

Fig. 7.

Effects of compression sleeve across movement tasks and positions in experiment 2. A: maintenance of M-wave across condition and movement tasks at the 3 o’clock elbow extension position. B: maintenance of M-wave across condition and movement tasks at the 6 o’clock elbow flexion position. C: effect of compression on H-reflex amplitude across movement tasks at the 3 o’clock elbow extension position. *Significant reduction in H-reflex amplitude pooled across movement task. D: effect of compression on H-reflex amplitude across movement tasks at the 6 o’clock elbow flexion position. No differences were present at this position. Values are means ± SE (P < 0.05).

Fig. 8.

Reaching accuracy across stimulation positions. *Significant reduction in the deviation from the intended target while wearing the compression apparel. Values are means ± SE (P < 0.05).