Gael Guilhem, Christophe Cornu, Arnaud Guével
Context: Resistance exercise training commonly is performed against a constant external ioad (isotonic) or at a constant velocity (isokinetic). Researchers comparing the effectiveness of isotonic and isokinetic resistance-training protocols need to equalize the mechanical stimulus (work and velocity) applied.
Objective: To examine whiether the standardization protocol could be adjusted and applied to an eccentric training program.
Design: Controlled laboratory study.
Setting: Controlled research laboratory. Patients or Other Participants: Twenty-one sport science male students (age = 20.6±1.5 years, height = 178.0 ±4.0 cm, mass = 74.5 ±9.1 kg).
Intervention(s): Participants performed 9 weeks of isotonic (n = 11 ) or isokinetic (n = 10) eccentric training of knee extensors that was designed so they would perform the same amount of angular work at the same mean angular velocity.
Main Outcome Measure(s): Angular work and angular velocity.
Results: The isotonic and isokinetic groups performed the same total amount of work (-185.2 ±6.5 kJ and -184.4 ±8.6 kJ, respectively) at the same angular velocity (21 ± 17s and 22°/s, respectively) with the same number of repetitions (8.0 and 8.0, respectively). Bland-Altman analysis showed that work (bias = 2.4%) and angular velocity (bias = 0.2%) were equalized over 9 weeks between the modes of training.
Conclusions: The procedure developed allows angular work and velocity to be standardized over 9 weeks of isotonic and isokinetic eccentric training of the knee extensors. This method could be useful in future studies in which researchers compare neuromuscular adaptations induced by each type of training mode with respect to rehabilitating patients after musculoskeletal injury.
Key Words: resistance exercise, muscle strength, knee extensors.
Uganet Hernández Rosa, Jorge Velasquez Tlapanco, Catalina Lara Maya S Enrique Villarreal Ríos, Lidia Martínez González, Emma Rosa Vargas Daza y Liliana Galicia Rodríguez
Reumatol Clin. 2012:8(1):10-14
Introduction: Osteoarthritis is a chronic joint disease; isometric exercise leads to the development of mechanical work and isokinetic exercise leads to better joint mobility.
Objectives: To compare the effectiveness of isometric versus isokinetic therapeutic exercises in patients with knee osteoarthritis.
Material and methods: Quasiexperimental study in a population of 45 to 75 year old patients with a diagnosis of knee osteoarthritis. Group 1 (experimental) was put under isokinetic exercises and group 2 (control) under isometric exercises. The sample size was of 33 patients per group; the allocation to the experimentation or control group was nonrandom, but stratified by degrees of knee osteoarthritis.
The effectiveness of the exercise was measured in three dimensions; muscle strength, joint range and pain. The intervention lasted eight weeks and the physical activity was carried out every third day. The statistical analysis included averages, standard deviation, pereentage, Chi square test, z test for two populations, t test for two independent populations and twin t test.
Results: The analysis of muselé strength comparing the eategories independently demonstrates differenees at 8 weeks; 33.3% of the isokinetie exercise is in the normal eategory and 15.2% in the isometric exercise (p= 0.04). There was not differenee of joint range between groups, despite finding a stage I range in 100.0% of the isokinetie group and 97.0% in the isometrie (p> 0.05) group. Pain was milder in the isokinetie exereise group at 8 weeks (p= 0.01 ).
Conclusions: Isokinetie exereises have a greater effectiveness than isometrie exercises for muscle strength and pain in patients with knee osteoarthritis. However, other studies with randomized designs are needed.
Andrew Wilcock, Matthew Maddocks, Mary Lewis, Paul Howard, Jacky Frisby, Sarah Bell, Bisharat El Khoury, Cathann Manderson, Helen Evans and Simon Mockett
BMC Palliative Care 2008, 7:3 doi:10.1186/1472-684X-7-3
Background: The cachexia-anorexia syndrome impacts on patients' physical independence and quality of life. New treatments are required and need to be evaluated using acceptable and reliable outcome measures, e.g. the assessment of muscle function. The aims of this study were to:
Methods: The test consisted of 25 repetitions of isokinetic knee flexion and extension at maximal effort while seated on a Cybex NORM dynamometer. Strength and endurance for the quadriceps and hamstrings were assessed as peak torque and total work and an endurance ratio respectively.
Thirteen patients and 26 volunteers completed the test on three separate visits. Acceptability was assessed by questionnaire, reliability by intraclass correlation coefficients (ICC) and tests of difference compared outcomes between and within groups.
Results: All subjects found the test acceptable. Peak torque and work done were reliable measures (ICC >0.80), but the endurance ratio was not. Muscle function did not differ significantly between the patient and a matched volunteer group or in either group when repeated after one month.
Conclusion: For patients with non-small cell lung cancer or mesothelioma, the Cybex NORM dynamometer provides an acceptable and reliable method of assessing muscle strength and work done. Muscle function appears to be relatively well preserved in this group and it appears feasible to explore interventions which aim to maintain or even improve this.
Διαθέσιμο για να το κατεβάσετε: http://www.biomedcentral.com/1472-684X/7/3.
Franco M. Impellizzeri1, Mario Bizzini1, Ermanno Rampinini2, Ferdinando Cereda3 and Nicola A. Maffiuletti1
Clin Physiol Funct Imaging (2008) 28, pp113–119
The main aimof this study was to examine the absolute and relative reliability of some commonly used strength imbalance indices such as concentric hamstring-toconcentric quadriceps ratio, eccentric hamstring-to-concentric quadriceps ratio and bilateral concentric and eccentric strength ratios. An additional aim was to examine the reliability of the peak torque and work of the knee extensor and flexor muscles measured using the Cybex NORM dynamometer. Eighteen physically active healthy subjects (mean ± standard deviation, age 23 ± 3 years, height 176 ± 5 cm, body mass 74 ± 8 kg) were tested three times with 96 h between sessions. Peak torque, average work, unilateral and bilateral ratios were determined at 60, 120, 180 and )60 s)1. Low (0Æ34) to moderate (0Æ87) relative reliability (intraclass correlation coefficient, ICC) was found for strength imbalance ratios with eccentric hamstringto-concentric quadriceps ratio showing the greater ICC (>0Æ80). High ICC values (0Æ90–0Æ98) were found for peak torque and average work. Absolute reliability (standard error of measurement) ranged from 3Æ2% to 8Æ7% for strength imbalance ratios and from 4Æ3% to 7Æ7% for peak torque and average work measurements. This study established the reliability of the most common strength imbalance ratios and of absolute isokinetic muscle strength assessed using the Cybex NORM.
Περισσότερα (αρχείο .pdf)
Bρείτε το άρθρο:
doi: 10.1111/j.1475-097X.2007.00786.x
KONSTANTINOS GIANNAKOPOULOS, ANASTASIA BENEKA, AND PARASKEVI MALLIOU
Department of Physical Education and Sports Science, Democritus University of Thrace, 69100 Komotini, Greece.
ABSTRACT. Giannakopoulos, K., A. Beneka, and P. Malliou. Isolated versus complex exercise in strengthening the rotator cuff muscle group. J. Strength Cond. Res. 18(2):144–148. 2004.—The purpose of this study was to compare 2 different training modes in improving shoulder cuff muscular performance.
Thirty-nine participants were randomly assigned into 3 groups: the isolated group exercised using 2-kg dumbbells; the complex group used a protocol with complex exercises; and the control group had no training. All participants trained for 6 weeks (3 times per week) and were evaluated isokinetically before (pretest) and after the training period (posttest).
Results showed that the complex group significantly improved their muscular performance, but the isolated group did not, indicating that isolated exercises are only effective when the training goal is to strengthen the weaker muscle group, but they must be replaced by more complex and closed-kinetic exercises in order to obtain considerable improvement of the rotator cuff strength.
The authors propose that a strengthening program should start with isolated movements for better stimulation of the weaker muscles and continue with complex exercise for more impressive strengthening.
KEY WORD: internal/external rotators, peak torque values.
P C Malliou, K Giannakopoulos, A G Beneka, A Gioftsidou, G Godolias
Br J Sports Med 2004;38:766–772. doi: 10.1136/bjsm.2003.009548
Background: Many studies have compared different training methods for improving muscular performance, but more investigations need to be directed to the restoration of muscular imbalances.
Objective: To determine the most effective training for altering strength ratios in the shoulder rotator cuff.
Methods: Forty eight physical education students were randomly assigned to four groups (12 per group):
Testing was performed in the supine position with the glenohumeral joint in 90˚ of abduction in the coronal lane, with a range of motion of 0–90˚ of external rotation and 0–65˚ of internal rotation at angular velocities of 60, 120, and 180˚/s. The test procedure was performed before and after the exercise period of six weeks.
Results: One way analysis of variance found no differences between the groups for the initial tests.
Analysis of variance with repeated measures showed that the strength ratios in all the experimental groups had altered after the exercise period, with the isokinetic group showing the most significant improvement.
Conclusions: Isokinetic strengthening is the most effective method of altering strength ratios of the rotator cuff muscle.
Br J Sports Med 2004; 38: 766-772
Θέμα: Ο λειτουργικός ρόλος των στροφαίων του ώμου απαιτεί αντικειμενική αξιολόγηση για την ανίχνευση πιθανών μυϊκών δυσαναλογιών και ασταθειών. Για το λόγο αυτό η παρούσα εργασία επιχειρεί μία συγκριτικη μελέτη διαφορετικών μεθόδων εξάσκησης με στόχο τον καθορισμό των πιο αποδοτικών από αυτές για την μεταβολή της αναλογίας δύναμης στους στροφείς τους ώμου. Τα αποτελέσματα της έρευνας δείχνουν ότι η ισοκινητική είναι η πιο αποτελεσματική μέθοδος για την επίτευξη της μυίκής ενδυνάμωσης.
Journal of Strength and Conditioning Research, 2004, 18(1), 114-148
Θέμα: Η συγκεκριμένη εργασία παρουσιάζει και συγκρίνει δύο διαφορετικούς τρόπους εξάσκησης του μυϊκού συμπλέγματος των στροφαίων του ώμου κατά τη διάρκεια ενός πειραματικού προγράμματος. Μία σειρά τόσο από απόλυτα επικεντρωμένες όσο και από πολυμερείς ασκήσεις εφαρμόσθηκαν σε μία ομάδα συμμετεχόντων κατά τη διάρκεια 6 εβδομάδων. Τα αποτελέσματα της μελέτης δείχνουν οτι ένα πρόγραμμα ενδυνάμωσης των μυών πρέπει να ξεκινά με επικεντρωμένες ασκήσεις για ενίσχυση των πιο αδύναμων μυών και να συνεχίζει με πολυμερείς ασκήσεις για καθολική ενδυνάμωση.
Kenneth McLeod, Sara Morley, Andrew Matsushima
J. Biomedical Science and Engineering, 2012, 5, 194-201 JBiSE
doi:10.4236/jbise.2012.54025 Published Online April 2012 (http://www.SciRP.org/journal/jbise/)
Muscle imbalances are a well accepted cause of mus-culo-skeletal pain, yet clinicians lack a simple, non- invasive, and reproducible means to assess muscle effort during activities of daily living. To address this issue, we have been developing vibromyography (VMG) as a means to quantitatively assess muscle mechanical effort such that accurate muscle effort ratios can be determined in the clinic. In this study, VMG was used to characterize muscle imbalances in older adults with low-level knee pain while they per-formed step-up and step-down activities. In addition to determining whether VMG can identify the im-balances previously reported in individuals with knee pain, we address the question of whether these knee muscle imbalances were a likely cause of knee pain, or whether the imbalances represented a coping re-sponse for pre-existing knee pain. A population (N = 30) of 35 - 85 year old men and women with a total of 42 painful knees were assessed. Robust multiple step- wise regression analysis identified weak hip abductor muscle effort relative to hamstring muscle effort as the best predictor of knee pain (p = 0.00006), with weak vastus lateralis effort in eccentric contraction, relative to concentric contraction, being the second best predictor (p = 0.0003). Muscle imbalances were able to account for 40% of the variation in reported pain, and the observed pattern of increasing knee pain with increasing quadriceps strength during con-centric contraction leads us to infer that the observed muscle imbalances are not the result of a protective action by the individual, but rather are a principle cause of the knee pain.
Keywords: Vibromyography; Knee Pain; Muscle Balance; Osteoarthritis Περισσότερα (αρχείο .pdf)
