The effect of muscle pain on elbow flexion and coactivation tasks

Abstract

The effects of muscle pain on movement can easily be observed in daily life routines. However, the influence of muscle pain on motor control strategies has not been fully clarified. In this human experimental study it was hypothesized that muscle pain affects the motor control of elbow flexion movements, in different combinations of range of motion and target size, by decreased agonistic muscle activity and increased antagonistic muscle activity with consequent implications on kinematic parameters. The effects of experimentally induced muscle pain on movement strategy for: (1) small and large range of motion (ROM) elbow flexion movements towards a wide target, (2) large ROM flexion movements towards a narrow and wide target, and (3) subsequent coactivation of agonistic and antagonistic muscles to elbow flexion were assessed. Muscle pain induced by injections of hypertonic saline (1 ml, 5.8%) in either m. biceps brachii or m. triceps brachii caused similar effects on the movements. For low accurate movements the initial (100 ms) integrated electromyographic (EMG) activity of m. biceps brachii was decreased during muscle pain. In contrast, integrated EMG of the entire m. biceps brachii burst was decreased by muscle pain only for small ROM at a low accuracy, which also showed decreased EMG activity of m. triceps brachii and m. brachioradialis, together with increased activity of m. trapezius. Finally, high accurate movements and post-movement coactivation were generally not modulated by muscle pain. In summary, the present study shows that acute muscle pain can perturb the motor control strategy, which might be highly important in occupational settings where such a change may need compensatory actions from other muscles and thereby eventually contribute to the development of musculoskeletal pain problems.

How does pain affect jaw muscle activity? The Integrated Pain Adaptation Model

“…11,[24][25][26][27] Although the Pain Adaptation Model was developed for human chronic pain, it is interesting to note that the model would predict increases in one but not both muscle groups in this experimental rat model. Furthermore, findings from human studies of the effects of pain on locomotor, 44 trunk, 23 or forelimb 48,49 muscle activity are also not always consistent with the Pain Adaptation Model. For example, many inconsistencies have recently been identified in the literature on the relation between chronic low-back pain and muscle activity, 23 and neither the Vicious Cycle Theory nor the Pain Adaptation Model adequately predicted the effects of back pain on trunk muscle activation.…”

“…55 It is possible, however, in some individuals, these changes in muscle activity could lead to further pain, injury and disability for reasons that have yet to be elucidated. 23,35,49,[56][57][58][59][60][61][62] This raises the possibility that the Integrated Pain Adaptation Model reflects, in one sense, a unification of components of the Vicious Cycle Theory and the Pain Adaptation Model.…”

Effect of load level and muscle pain intensity on the motor control of elbow-flexion movements

“…Delayed reaction time has been found after musculoskeletal injuries (Taimela and Kujala 1992). Experimental (Madeleine et al 1999b;Ervilha et al 2004) and clinical (Radebold et al 2000(Radebold et al , 2001Hodges 2001) studies have shown that the reaction time is systematically prolonged during acute and chronic pain conditions. Moreover, Luoto et al (1998) showed that the severity of low-back pain is associated with longer reaction times.…”

“…Finally, Birch et al (2000) concluded that experimental muscle pain had no effect on work performance when using a computer mouse but did modulate muscle activity during a low-precision task while no effect was found during high-precision task. In line, experimentally induced muscle pain did not change the overall EMG activity during high-precision elbow-joint movements but caused EMG activity changes in the overall muscle activity and in the initial EMG burst during low-precision tasks, which suggests changes in the motor planning (Ervilha et al 2004). Thus, it is clear that the motor strategy is disturbed by muscle pain.…”

Influence of type of movement termination and sport practice on muscle activity during elbow extension movements. (Efecto del tipo de finalización del movimiento y práctica deportiva sobre la actividad muscular en el movimiento de extensión del codo).

“…Figure 1 shows the position of the participants before and after the elbow extension movement. The participants performed 10 trials (Ervilha and Arendt-Nielsen, 2004) in two movement conditions (impact and pointing movements), and trials of different instructions were executed with a random order. The instructions to the participants were: (i) "punch the target as quickly as possible", and (ii) "move your fist to the target as quickly and accurately as possible.…”