Plantarflexor muscle function in healthy and chronic Achilles tendon pain subjects evaluated by the use of EMG and PET imaging

Abstract

(2014). Plantarflexor muscle function in healthy and chronic Achilles tendon pain subjects evaluated by the use of EMG and PET imaging. Clinical Biomechanics, 29,[567][568][569][570] Dette er siste tekst-versjon av artikkelen, og den kan inneholde små forskjeller fra forlagets pdf-versjon. Forlagets pdf-versjon finner du på www.sciencedirect.com: http://dx.doi.org/10. 1016/j.clinbiomech.2014.03.003 This is the final text version of the article, and it may contain minor differences from the journal's pdf version. Abstract: ABSTRACT Background: Achilles tendon pathologies may alter the coordinative strategies of synergistic calf muscles. We hypothesized that both surface electromyography and positron emission tomography would reveal differences between symptomatic and asymptomatic legs in Achilles tendinopathy patients and between healthy controls. Methods: Eleven subjects with unilateral chronic Achilles tendon pain (28 yr) and eleven matched controls (28 yr) were studied for triceps surae and flexor hallucis longus muscle activity in response to repetitive isometric plantarflexion tasks performed at 30% of maximal voluntary contraction using surface electromyography and glucose uptake using positron emission tomography. Additionally, Achilles tendon glucose uptake was quantified. Findings: Normalized myoelectric activity of soleus was higher (P<0.05) in the symptomatic leg versus the contralateral and control legs despite lower absolute force level maintained (P<0.005). Electromyography amplitude of flexor hallucis longus was also greater on the symptomatic side compared to the healthy leg (P<0.05). Both the symptomatic and asymptomatic legs tended to have higher glucose uptake compared to the control legs (overall effect size: 0.9 and 1.3, respectively). Achilles tendon glucose uptake was greater in both legs of the patient group (P<0.05) compared to controls. Maximal plantarflexion force was ~14% greater in the healthier leg compared to the injured leg in the patient group.Interpretations: While the electromyography showed greater relative amplitude in the symptomatic leg, the results based on muscle glucose uptake suggested relatively similar behavior of both legs in the patient group. Higher glucose uptake in the symptomatic Achilles tendon suggests a higher metabolic demand. Background: Achilles tendon pathologies may alter the coordinative strategies of synergistic calf PLANTARFLEXOR MUSCLE FUNCTION IN HEALTHY AND CHRONIC ACHILLES

FDG-PET detects nonuniform muscle activity in the lower body during human gait

“…Regions that were identified as having greater uptake were generally in areas that would have a greater proportion of connective tissue relative to contractile proteins. Previous research has shown that glucose uptake in the Achilles tendon during isometric tasks is lower compared with the triceps surae muscles . This would suggest that we should have seen lower relative uptake in these areas, while in fact they were greater.…”

Altered Strength Profile in Achilles Tendinopathy: A Systematic Review and Meta-Analysis

“…Isometric Strength. Small to moderate effect sizes were reported in 2 studies, 45,48 indicating reduced isometric PF strength in those with AT (Hedges g ¼ 0.46-0.78). These effect sizes equated to a reduction of 5% to 12% between the symptomatic and asymptomatic sides or between the symptomatic side and asymptomatic controls.…”

“…A total of 13 studies 11,19,[40][41][42][43][44][45][46][47][48][49][50] included both male and female participants, whereas 6 studies 13,39,[51][52][53][54] included men only. The authors of 8 studies 13,39,42,43,[48][49][50][51] compared strength measures between symptomatic and asymptomatic participants, the authors of 8 studies 11,40,41,[44][45][46][47]52 compared strength values between injured and uninjured sides of the same participants, and the authors of 4 studies 48,[53][54][55] compared strength variables between the injured and uninjured sides of the same participant and between the injured side and asymptomatic participants. Strength values between the ''most'' and ''least'' symptomatic sides were compared in 1 study.…”

“…Researchers investigated PF PT at slow speeds ( 1208/s) in 7 studies 11,[39][40][41]47,49,54 and at fast speeds (.1208/s) in 7 studies. 11,[39][40][41]46,47,54 Maximal isometric-strength measures were reported in 3 studies 13,45,48 using various force apparatuses. Silbernagel et al 19 used a variety of heel-raise tests to quantify both concentric and eccentric PF strength and heel-raise-test outcomes using a customized springloaded linear encoder.…”

[18F]-FDG positron emission tomography—an established clinical tool opening a new window into exercise physiology

“…Therefore, although both methods measure muscle activation from their own perspective, the results will not necessarily correlate with each other. However, some attempts to compare the methods have been done (39,40,41,54), but the results have not been shown to be consistent.…”