A cross-sectional study comparing strength profile of dorsal and palmar flexor muscles of the wrist in epicondylitis and healthy men.

BACKGROUND: Strength training has been proposed by several authors to treat Lateral Epicondylitis. However, there is still a lack of information concerning muscle weakness and its relationship to imbalances and fatigability of forearm muscles during dynamic conditions in subjects after epicondylitis recovery. AIM: To analyze the relationship between lateral humeral epicondylitis, and forearm muscle strength and fatigue. SETTING: Rehabilitation specialized center POPULATION: Cross-sectional study in eight former epicondylitis men free of symptoms and actively working at the moment of the evaluation and eight healthy men volunteers. METHODS: Isokinetic tests were performed at different velocities in order to assess strength in concentric and eccentric contractions. Additionally, a long-term concentric test was carried out in order to analyze strength during endurance. The following variables were analyzed: Average torque of dorsal and palmar flexors of the wrist and ratio of agonist/antagonist for non-endurance contractions; length of initial and final plateaus and the slope of average torque decay during the endurance test. RESULTS: In both groups, average torque produced by palmar flexor muscles was higher than that produced by dorsal flexor muscles. Patients showed higher strength in palmar flexor muscles, whereas dorsal flexor strength was similar for both populations. Palmar flexor vs. dorsal flexor ratio was significantly higher in patients for eccentric contractions. Regarding fatigue, results showed that torque decreased earlier in patients. CONCLUSIONS AND CLINICAL REHABILITATION IMPACT: Both palmar flexor force and palmar/dorsal ratio in eccentric exercise were significantly higher in patients. This finding indicates a muscular imbalance in patients underlying the epicondylitis condition. Additionally, former patients fatigued earlier. Findings indicate that muscle imbalances and fatigability might be related to lateral epicondylitis. This information may be useful in the design and monitoring of programs intended for lateral epicondylitis rehabilitation. More studies are necessary to conclude if these differences are cause or consequence of the epicondylitis.

Knee isokinetic test-retest: a multicentre knee isokinetic test-retest study of a fatigue protocol.

AIM: The aim of this study was to establish the test-retest reliability of a knee extensor and flexor muscle fatigue protocol using a biodex system 3 isokinetic dynamometer. METHODS: Three-outpatient Rehabilitation Departments undertook the study. Fatigue was evaluated in the dominant knee of 90 healthy female volunteers, non-sportswomen, aged between 20 and 40. They performed 40 consecutive concentric knee flexions and extensions, at 120 degrees /s, on a Biodex 3 isokinetic dynamometer. Two evaluations were done over a period of seven days. Analysed variables were: maximal repetition of total work, maximal work repetition number, work to body weight ratio, total work, work during first and last third of the protocol, fatigue ratio, work fatigue. Statistical analysis determined mean values, medians and box-plots. Intraclass Correlation Coefficients (ICC) (confidence interval 95 %), t-test and one-way analysis of variance (ANOVA) evaluated reliability. Difference of means (di), standard error of measurement (SEM) and 95% of interval confidence (IC di) were also calculated (P<0.05). RESULTS: All participants completed the study. Reliability data were excellent (ICC>0.75) for total work (0.85), work during first third (0.80) and last third (0.80) in extension, and for total work in flexion. Reliability data were fair to good (ICC 0.4-0.75) for the rest of the variables. Median varied less than 20% in all cases during test-retest. CONCLUSION: This knee fatigue protocol is reliable for flexion and extension, above all when using the total work as a variable. The desirability of multicentre studies in rehabilitation and standardisation of protocols is emphasised.

Evaluation of muscle activity and fatigue in extensor forearm muscles during isometric contractions.

Work-related upper extremity disorders as epycondylitis and tendonitis are closely related to localized muscle fatigue of extensor forearm muscles. The aim of this work is to evaluate levels of activity, fatigue and interactions between the main extensor muscles of the wrist. Surface EMG signals were acquired from extensor carpi radialis (ECR), extensor digitorum comunis (EDC) and extensor carpi ulnaris (ECU) muscles during isometric contractions using linear electrode array technique. Parameters such as muscle fiber conduction velocity (CV), EMG average rectified value (ARV) and frequency parameters were estimated to study muscle activity during selective contractions, during a non specific task at different percentage of the maximum voluntary contraction (MVC) level and during a fatiguing exercise at 50% MVC. Results show that it is possible to enhance significantly ECR and ECU muscle ARV during their selective activation. Moreover, in the non selective task, ECU muscle ARV significantly decreases with respect to the other muscles with the increase of the MVC level. The activity of ECR muscle in a non specific task is predominant with respect to the other muscles at 80%MVC. EMG spectral parameters and CV show fatigue in all muscles during a sustained contraction at 50%MVC.

Influence of walking speed on lower limb muscle activity and energy consumption during treadmill walking of hemiparetic patients.

OBJECTIVE: To identify the relationship between treadmill speed and energy consumption and lower limb muscle activity in ambulatory hemiparetic patients. DESIGN: Experimental cohort. SETTING: Inpatient rehabilitation clinic. PARTICIPANTS: Twenty-four ambulatory hemiparetic subjects. INTERVENTION: Subjects walked harness-secured on the treadmill with no body-weight support at self-reported (V SAS), slow (V SAS - 25%), and fast (V SAS + 25%) speed. MAIN OUTCOME MEASURES: Assessment of basic, limb-dependent cycle parameters, lower limb muscle activity, and energy consumption. RESULTS: Cadence (r = .75), stride length (r = .78), relative double-support duration (r = .31), mean muscle activity of the paretic tibialis anterior (r = .12), gastrocnemius (r = .37), vastus lateralis (r =.19), rectus femoris (r = .31), and biceps femoris (r = .45) muscles, as well as heart rate (r = .54), correlated positively with treadmill speed. Mean maximum heart rate was 131 beats/min. Energy (r = -.67) and cardiac cost (r = -.55) correlated negatively with gait speed (ie, patients walked more efficiently at faster velocities). The qualitative muscle activation pattern analysis revealed earlier (more normal) onset of activation of gastrocnemius, vastus lateralis, biceps femoris, and gluteus medius. CONCLUSIONS: Patients should try to walk fast on the treadmill, thereby facilitating relevant weight-bearing muscles and improving gait efficiency.