Muscle activation during maximum voluntary contraction and m-wave related in healthy but not in injured conditions: Implications when normalizing electromyography

Zellers, Jennifer A.; Parker, Sheridan; Marmon, Adam R.; Silbernagel, Karin Grävare

doi:10.1016/j.clinbiomech.2019.07.007

Cited by 7 publications

(9 citation statements)

References 25 publications

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“…15 Tendon elongation has been suggested to underlie changes in walking, 2,42 running, 8,21,40 and jumping mechanics throughout the course of recovery. 31,40,43,44 Additionally, investigators have observed moderate-to-strong relationships between tendon elongation and deficits in triceps surae muscle isometric strength, particularly at end-range plantarflexion, even in individuals >10 years after injury. 16 Combined with the results of the present study, these data indicate that the triceps surae musculature continues to have capacity to produce force, but over a limited range, pointing to the need to intervene with the goal of restoring muscle and tendon length, likely very early after rupture.…”

Section: Discussionmentioning

confidence: 99%

“…25,28,35,37 Muscle activation and lower limb biomechanics (but not Achilles tendon load) have been previously reported for the hopping task, 43 and muscle activation has been previously reported for the CMJ task. 44 The right limb was tested first for all participants to quasi-randomize testing of the repaired and uninjured sides. For the heel-rise task, participants were positioned standing unilaterally on a 10°incline box.…”

Section: Study Design and Participantsmentioning

confidence: 99%

“…during running, jumping, and participating in sports in recreationally active people. 8,21,31,40,43,44 Achilles tendon ruptures stimulate gross structural changes in both the tendon and triceps surae musculature. After rupture, the Achilles tendon heals in a permanently elongated position 22,33,36 and never regains the material properties of healthy tendon tissue.…”

mentioning

confidence: 99%

“…18 Fascicle remodeling and increased pennation persist 3 to 6 months after injury. 1,30 In addition to shorter and more pennate muscle fascicles, 24 muscle atrophy 15,16,24,32,44 and fatty infiltration 15,16 have been reported beyond 1 year after injury.…”

mentioning

confidence: 99%

“…3,29,38 From a biomechanical standpoint, Achilles tendon ruptures permanently reduce performance during running, jumping, and participating in sports in recreationally active people. 8,21,31,40,43,44…”

mentioning

confidence: 99%

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Functional Ankle Range of Motion but Not Peak Achilles Tendon Force Diminished With Heel-Rise and Jumping Tasks After Achilles Tendon Repair

2021

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Background: Deficits in sporting performance after Achilles tendon repair may be due to changes in musculotendinous unit structure, including tendon elongation and muscle fascicle shortening. Purpose/Hypothesis: The purpose was to discern whether Achilles tendon rupture reduces triceps surae muscle force generation, alters functional ankle range of motion, or both during sports-related tasks. We hypothesized that individuals who have undergone Achilles tendon repair lack the functional ankle range of motion needed to complete sports-related tasks. Study Design: Descriptive laboratory study. Methods: The study included individuals 1 to 3 years after treatment of Achilles tendon rupture with open repair. Participants (n = 11) completed a heel-rise task and 3 jumping tasks. Lower extremity biomechanics were analyzed using motion capture. Between-limb differences were tested using paired t test. Results: Pelvic vertical displacement was reduced during the heel-rise (mean difference, −12.8%; P = .026) but not during the jumping task ( P > .1). In the concentric phase of all tasks, peak ankle plantarflexion angle (range of mean difference, −19.2% to −48.8%; P < .05) and total plantar flexor work (defined as the area under the plantar flexor torque – ankle angle curve) (range of mean difference, −9.5% to −25.7%; P < .05) were lower on the repaired side relative to the uninjured side. No significant differences were seen in peak Achilles tendon load or impulse with any of the tasks. There were no differences in plantar flexor work or Achilles tendon load parameters during eccentric phases. Conclusion: Impaired task performance or increased demands on proximal joints were observed on the repaired side in tasks isolating ankle function. Tasks that did not isolate ankle function appeared to be well recovered, although functional ankle range of motion was reduced with rupture. Reduced plantar flexor muscle-tendon unit work supports previous reports that an elongated tendon and shorter muscle fascicles caused by Achilles tendon rupture constrain functional capacity. Achilles tendon peak load and impulse were not decreased, suggesting that reduced and shifted functional ankle range of motion (favoring dorsiflexion) underlies performance deficits. Clinical Relevance: These findings point to the need to reduce tendon elongation and restore muscle length of the triceps surae after Achilles tendon rupture in order to address musculature that is short but not necessarily weak for improved performance with sports-related activities.

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