New regimen for eccentric calf-muscle training in patients with chronic insertional achilles tendinopathy : results of a pilot study

Background: Chronic painful insertional Achilles tendinopathy is seen in both physically active and non-active individuals. Painful eccentric training, where the patients load the Achilles tendon into full dorsiflexion, has shown good results in patients with mid-portion Achilles tendinosis. However, only 32% of patients with insertional Achilles tendinopathy had good clinical results with that type of eccentric training regimen.

Aim: To investigate whether a new model of painful eccentric training had an effect on chronic painful insertional Achilles tendinopathy.

Patients and methods: 27 patients (12 men, 15 women, mean age 53 years) with a total of 34 painful Achilles tendons with a long duration of pain (mean 26 months), diagnosed as insertional Achilles tendinopathy, were included. The patients performed a new model of painful eccentric training regimen without loading into dorsiflexion. This was done as 3x15 reps, twice a day, 7 days/week, for 12 weeks. Pain during Achilles-tendon-loading activity (VAS) and patient’s satisfaction (back to previous activity) were evaluated.

Results: At follow-up (mean 4 months) 18 patients (67%, 23/34 tendons) were satisfied and back to their previous tendon-loading activity. Their mean VAS had decreased from 69.9 (SD 18.9) to 21 (SD 20.6) (p<0.001). Nine patients (11 tendons) were not satisfied with the treatment, although their VAS was significantly reduced from 77.5 (8.6) to 58.1 (14.8) (p<0.01).

Conclusion: In this short-term pilot study this new model of painful eccentric calf-muscle training showed promising clinical results in 67% of the patients.

Cellular adaption to repeated eccentric exercise-induced muscle damage

Eccentrically biased exercise results in skeletal muscle damage and stimulates adaptations in muscle, whereby indexes of damage are attenuated when the exercise is repeated. We hypothesized that changes in ultrastructural damage, inflammatory cell infiltration, and markers of proteolysis in skeletal muscle would come about as a result of repeated eccentric exercise and that gender may affect this adaptive response. Untrained male (n = 8) and female (n = 8) subjects performed two bouts (bout 1 and bout 2), separated by 5.5 wk, of 36 repetitions of unilateral, eccentric leg press and 100 repetitions of unilateral, eccentric knee extension exercises (at 120% of their concentric single repetition maximum), the subjects' contralateral nonexercised leg served as a control (rest). Biopsies were taken from the vastus lateralis from each leg 24 h postexercise. After bout 2, the postexercise force deficit and the rise in serum creatine kinase (CK) activity were attenuated. Women had lower serum CK activity compared with men at all times (P < 0.05), but there were no gender differences in the relative magnitude of the force deficit. Muscle Z-disk streaming, quantified by using light microscopy, was elevated vs. rest only after bout 1 (P < 0.05), with no gender difference. Muscle neutrophil counts were significantly greater in women 24 h after bout 2 vs. rest and bout 1 (P < 0.05) but were unchanged in men. Muscle macrophages were elevated in men and women after bout 1 andbout 2 (P < 0.05). Muscle protein content of the regulatory calpain subunit remained unchanged whereas ubiquitin-conjugated protein content was increased after both bouts (P < 0.05), with a greater increase after bout 2. We conclude that adaptations to eccentric exercise are associated with attenuated serum CK activity and, potentially, an increase in the activity of the ubiquitin proteosome proteolytic pathway.

Gender differences in muscle inflammation after eccentric exercise

Unaccustomed exercise is followed by delayed-onset muscle soreness and morphological changes in skeletal muscle. Animal studies have demonstrated that women have an attenuated response to muscle damage. We studied the effect of eccentric exercise in untrained male (n = 8) and female (n = 8) subjects using a unilateral exercise design [exercise (Ex) and control (Con) legs]. Plasma granulocyte counts [before (Pre) and 48 h after exercise (+48h)] and creatine kinase activity [Pre, 24 h after exercise (+24h), +48h, and 6 days after exercise (+6d)] were determined before (Pre) and after (+24h, +48h, +6d) exercise, with biopsies taken from the vastus lateralis of each leg at +48h for determination of muscle damage and/or inflammation. Plasma granulocyte counts increased for men and decreased for women at +48h (P < 0.05), and creatine kinase activity increased for both genders at +48h and +6d (P < 0.01). There were significantly greater areas of both focal (P < 0.001) and extensive (P < 0.01) damage in the Ex vs. Con leg for both genders, which was assessed by using toluidine blue staining. The number of leukocyte common antigen-positive cells/mm2 tissue increased with exercise (P < 0.05), and men tended to show more in their Ex vs. Con leg compared with women (P = 0.052). Men had a greater total (Ex and Con legs) number of bcl-2-positive cells/mm2 tissue vs. women (P < 0.05). Atrophic fibers with homogeneous bcl-2-positive staining were seen only in men (n = 3). We conclude that muscle damage is similar between genders, yet the inflammatory response is attenuated in women vs. men. Finally, exercise may stimulate the expression of proteins involved in apoptosis in skeletal muscle.

Two maximal isometric contractions attenuate the magnitude of eccentric exercise-induced muscle damage

This study investigated whether maximal voluntary isometric contractions (MVC-ISO) would attenuate the magnitude of eccentric exercise-induced muscle damage. Young untrained men were placed into one of the two experimental groups or one control group (n = 13 per group). Subjects in the experimental groups performed either two or 10 MVC-ISO of the elbow flexors at a long muscle length (20° flexion) 2 days prior to 30 maximal isokinetic eccentric contractions of the elbow flexors. Subjects in the control group performed the eccentric contractions without MVC-ISO. No significant changes in maximal voluntary concentric contraction peak torque, peak torque angle, range of motion, upper arm circumference, plasma creatine kinase (CK) activity and myoglobin concentration, muscle soreness, and ultrasound echo intensity were evident after MVC-ISO. Changes in the variables following eccentric contractions were smaller (P < 0.05) for the 2 MVC-ISO group (e.g., peak torque loss at 5 days after exercise, 23% ± 3%; peak CK activity, 1964 ± 452 IU·L^–1; peak muscle soreness, 46 ± 4 mm) or the 10 MVC-ISO group (13% ± 3%, 877 ± 198 IU·L^–1, 30 ± 4 mm) compared with the control (34% ± 4%, 6192 ± 1747 IU·L^–1, 66 ± 5 mm). The 10 MVC-ISO group showed smaller (P < 0.05) changes in all variables following eccentric contractions compared with the 2 MVC-ISO group. Therefore, two MVC-ISO conferred potent protective effects against muscle damage, whereas greater protective effect was induced by 10 MVC-ISO, which can be used as a strategy to minimize muscle damage.

Increased cross-education of muscle strength and reduced corticospinal inhibition following eccentric strength training

AIM: Strength training of one limb results in a substantial increase in the strength of the untrained limb, however, it remains unknown what the corticospinal responses are following either eccentric or concentric strength training and how this relates to the cross-education of strength. The aim of this study was to determine if eccentric or concentric unilateral strength training differentially modulates corticospinal excitability, inhibition and the cross-transfer of strength. METHODS: Changes in contralateral (left limb) concentric strength, eccentric strength, motor-evoked potentials, short-interval intracortical inhibition and silent period durations were analyzed in groups of young adults who exercised the right wrist flexors with either eccentric (N=9) or concentric (N=9) contractions for 12 sessions over 4weeks. Control subjects (N=9) did not train. RESULTS: Following training, both groups exhibited a significant strength gain in the trained limb (concentric group increased concentric strength by 64% and eccentric group increased eccentric strength by 62%) and the extent of the cross-transfer of strength was 28% and 47% for the concentric and eccentric group, respectively, which was different between groups (P=0.031). Transcranial magnetic stimulation revealed that eccentric training reduced intracortical inhibition (37%), silent period duration (15-27%) and increased corticospinal excitability (51%) compared to concentric training for the untrained limb (P=0.033). There was no change in the control group. CONCLUSION: The results show that eccentric training uniquely modulates corticospinal excitability and inhibition of the untrained limb to a greater extent than concentric training. These findings suggest that unilateral eccentric contractions provide a greater stimulus in cross-education paradigms and should be an integral part of the rehabilitative process following unilateral injury to maximize the response.

Torque, myoeletric sygnal and heart rate responses during concentric and eccentric exercises in older men

Background: The literature reports that the eccentric muscular action produces greater force and lower myoelectric activity than the concentric muscular action, while the heart rate (HR) responses are bigger during concentric contraction. Objectives: To investigate the maximum average torque (MAT), surface electromyographic (SEMG) and the heart rate (HR) responses during different types of muscular contraction and angular velocities in older men. Methods: Twelve healthy men (61.7 +/- 1.6years) performed concentric (C) and eccentric (E) isokinetic knee extension-flexion at 60 degrees/s and 120 degrees/s. SEMG activity was recorded from vastus lateralis muscle and normalized by Root Mean Square-RMS (mu V) of maximal isometric knee extension at 60 degrees. HR (beats/min) and was recorded at rest and throughout each contraction. The data were analyzed by the Friedman test for repeated measures with post hoc Dunn's test (p<0.05). Results: The median values of MAT (N.m/kg) was smaller and the RMS (mu V) was larger during concentric contraction (C60 degrees/s=2.80 and 0.99; C120 degrees/s=2.46 and 1.0) than eccentric (E60 degrees/s=3.94 and 0.85; E120 degrees/s=4.08 and 0.89), respectively. The HR variation was similar in the four conditions studied. Conclusion: The magnitude of MAT and RMS responses in older men were dependent of the nature of the muscular action and independent of the angular velocity, whereas HR response was not influenced by these factors.

A cross-over randomised clinical trial of eccentric occlusion in complete dentures

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Variation of the Equator due to a Highly Inclined and Eccentric Disturber

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Orbital perturbations using geopotential coefficients up to high degree and order: Highly eccentric orbits

Several methods have been proposed for calculations of the eccentricity function for a high value of the eccentricity, however they cannot be used when the high degree and order coefficients of gravity fields are taken into account. The method proposed by Wnuk(1) is numerically stable in this case, but when is used. a large number of terms occurs in formulas for geopotential perturbations. In this paper we propose an application of expansions of some functions of the eccentric anomaly E as well as Hansen coefficients in power series of (e - e*), where e* is a fixed value of the eccentricity derived by da Silva Fernandes(2,3,4). These series are convergent for all e < 1.

Dissociated time course recovery between rate of force development and peak torque after eccentric exercise

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)