Isokinetics and Exercise Science - Volume 23, issue 3
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Isokinetics and Exercise Science (IES) is an international journal devoted to the study of theoretical and applied aspects of human muscle performance. Since isokinetic dynamometry constitutes the major tool in this area, the journal takes a particular interest in exploring the considerable potential of this technology.
Isokinetics and Exercise Science publishes studies associated with the methodology of muscle performance especially with respect to the issues of reproducibility and validity of testing, description of normal and pathological mechanical parameters which are derivable from muscle testing, applications in basic research topics such as motor learning paradigms and electromyography. The journal also publishes studies on applications in clinical settings and technical aspects of the various measurement systems employed in human muscle performance research.
Isokinetics and Exercise Science welcomes submissions in the form of research papers, reviews, case studies and technical reports from professionals in the fields of sports medicine, orthopaedic and neurological rehabilitation and exercise physiology.
Abstract: BACKGROUND: A novel way to evaluate muscle strength and functioning in the lower limbs is to measure how high a person could step up on a platform, the so called Maximal Step-up Test (MST). Studies of healthy persons and overweight women have shown that the maximal step-up height (MSH) is associated with both muscle strength and physical function, but no study has assessed persons after stroke. OBJECTIVE: To evaluate the relationship between isokinetic and isometric knee muscle strength and maximal step-up height after stroke. METHODS: A convenience sample of 21 ambulatory persons with…stroke (13 men and eight women; mean age 63 ± 12 years; mean time since stroke onset 26 ± 36 months). Isokinetic concentric knee extension and knee flexion strength at 60°/s and isometric knee extension strength at 90° were measured for both lower limbs with a Biodex dynamometer. Maximal step-up height was measured using a 40 cm × 60 cm platform, which could be raised from 3 cm to 45 cm with 3 cm intervals. The relationship between knee muscle strength (normalized to body weight) and the maximal step-up height was analysed with the Pearson's correlation coefficient (r). RESULTS: There were significant but only moderate relationships between the paretic isokinetic knee extension, and flexion, strength and maximal step-up height, r= 0.49; p < 0.05, and r= 0.57; p < 0.01, respectively. CONCLUSION: These moderate relationships indicate that muscle weakness is only partially associated with maximal step-up height after stroke. The MST may therefore have limited value in the assessment of muscle strength after stroke.
Abstract: BACKGROUND: Core strengthening is a significant component of training programs utilized to optimize athletic performance, reduce injury, and facilitate return from injury. Reliable and valid clinical measures of core strength are necessary to determine the effectiveness of these programs. OBJECTIVE: The purpose was to determine the reliability and validity of three medicine ball toss tests (MBTs). METHODS: A total of 20 healthy, physically active individuals participated. Session one included isokinetic strength testing (trunk flexion/extension, and right/left rotation) and MBTs (forward, backward, and right/left rotation); session two included only the MBTs. Average peak torque during…strength testing and the average distance of three MBTs in each direction were analyzed. Intraclass correlations were calculated to determine the reliability of the MBTs between sessions, while validity between MBTs and strength was assessed though Pearson correlations. RESULTS: Significant ICCs were observed between forward, backward, and right/left rotation MBTs (ICC = 0.835; ICC = 0.835; ICC = 0.870; ICC = 0.909; p< 0.001, respectively). No significant correlations were observed between the MBTs and corresponding measures of strength. CONCLUSION: Results illustrate that MBTs have excellent reliability but are not related to isokinetic strength as measured by average peak torque. This lack of relationship may be due to differences in muscles examined, contraction type, and/or motion performed.
Abstract: BACKGROUND: Muscle strength depends among other factors on its length, i.e., the angular position of the joint it spans. However, these relationship is often neglected in the construction of training machines. OBJECTIVE: The aim of this study was to verify the effectiveness of a variable-cam during strength training. METHODS: Thirty-two men divided into two groups participated in an 8-week intensive strength training of elbow flexors. One group (C) trained on a machine with a cam developed in the shape corresponding to the strength change characteristics of flexor muscles as a function of the angular…position in the elbow joint. The second group (D) trained on a machine with a disc plate. The effects of the training were evaluated on the basis of changes in the value of PT measured under isokinetic conditions, anthropometric parameters, and CK activity. RESULTS: After the end of the training, a significant increase in the values of the PT and anthropometric parameters were observed only in group C. Weekly changes of CK activity appeared only in the group exercising with a cam, while in the group exercising on the machine with a disc plate, the two-day rest turned out to be too short for the elimination of the CK molecules from the blood to occur. CONCLUSIONS: Strength training using a machine with a muscle-specific adjusted cam is especially effective in the case of the elbow flexors.
Keywords: Intensive training, biceps brachii, isokinetic muscle strength, CK activity
Abstract: BACKGROUND: Eccentric contractions (ECC)-induced muscle damage and activation pattern are not fully understood. OBJECTIVE: To investigate the activation level and damage in each muscle and site after ECC. METHODS: Eleven men performed 30 isokinetic ECC of the elbow flexors. Maximal voluntary isometric contraction (MVC) torque, range of motion of the elbow joint (ROM), delayed onset muscle soreness (DOMS), transverse relaxation time (T2), and cross-sectional area (CSA) were measured immediately before, immediately after, and 1, 3, 5 days after ECC. RESULTS: MVC and ROM significantly decreased while DOMS significantly increased until 3 days…after ECC. The CSA of the brachialis significantly increased after ECC. The T2 in biceps brachii and middle and distal brachialis increased significantly at post (p< 0.01) day 1 (middle; p< 0.01, distal; biceps brachii, p< 0.05, brachialis, p< 0.01), and day 3 (middle; p< 0.01, distal; biceps brachii, p< 0.05, brachialis, p< 0.01). In addition, after 5 days only the distal brachialis has shown a significant increase (p< 0.01). CONCLUSIONS: Following maximal ECC the activation pattern and muscle damage differ among the elbow flexors depending upon the individual muscle and site of recording.
Keywords: Lengthening, transverse relaxation time, elbow flexors, site-specific activation
Abstract: BACKGROUND: Although transfer of unilateral training has been quite widely explored, few studies have focused on gains achieved due to concentric isokinetic training of the non-dominant side. OBJECTIVE: To examine the effects of unilateral non-dominant (ND) isokinetic knee extension and flexion training at 60°/s on ipsilateral and contralateral knee extension and flexion peak moment (PM) in active female population as well investigate the speed specificity nature of this protocol. METHODS: Thirty female were divided into two groups: experimental and control. The experimental group trained concentrically the ND flexors and extensors at 60°/s according to…the following protocol: 5-6 reps X 2-4 sets X 3d X 4w at 100% effort while PM at pre- and post-training was tested concentrically at 60 and 180°/s. RESULTS: Significant (p< 0.05) increases in the extensors and flexors PM peak moment in both the trained and untrained limb were noted in the experimental group, ranging 19-27% and 12-17%, respectively. The effects were speed specific in the trained but not in untrained limb. No changes were noted in the PM of the control group. CONCLUSIONS: In physically active female population, concentric isokinetic training of the ND knee extensors and flexors at 60°/s significantly increase the strength of these muscles at the trained and untrained limb. This cross-education was not speed specific and therefore may obviate the need to use a multiple speed protocol.
Abstract: PURPOSE: This review is aimed at describing the methods used in knee extensor eccentric resistance training in healthy subjects and at evaluating the adaptations in strength, activation and structure of this muscle group. METHODS: Seventy-five studies were carefully analyzed and 30 are considered in this review. RESULTS: Training programs comprised of 1-4 sessions per week for a period ranging from four to 20 weeks with isokinetic dynamometers or conventional strength training machines were considered. Isokinetic eccentric training programs included 1-6 sets of 6-12 repetitions, while isotonic eccentric training programs consisted of 3-7 sets of 5-10…repetitions. Eccentric strength gains per training session (0.45-3.42%) were typically found to be greater compared to isometric (0.08-1.30%) and concentric (0.23-1.44%) strength gains. Quadriceps activation was improved in tests performed eccentrically and isometrically, but there is poor evidence of increased concentric activation and reduced co-activation of antagonistic muscles. Regarding muscle structure, significant hypertrophic responses have been demonstrated through increases in anatomical/physiological cross-sectional area, muscle thickness and fiber diameter. Most studies measuring muscle architectural changes reported increased fascicle lengths without changes in pennation angle. Adaptations in fiber type distribution were inconsistent. CONCLUSIONS: Strength gains following knee extensor eccentric training are caused by neural and structural adaptations, and may contribute to physical fitness in healthy populations and health improvement in patients.
Abstract: BACKGROUND: Falls are a major health problem among the elderly, and balance exercises can improve balance in the elderly and help reduce the risk of falls. OBJECTIVE: The purpose of the present study was to investigate the effect of balance training using Pedalo equipment on balance and fear of falling in elderly people. METHODS: Nineteen elderly people participated in this study center. Subjects performed balance training using four types of Pedalo equipment: the Stabilizer Therapy, Reha-Wipp, Reha-Bar, and Spring Board, for 30 minutes, 3 times a week for 6 weeks. The…Force platform, the Berg Balance Scale (BBS), and the Timed Up and Go (TUG) test were used to evaluate balance function, and the Fall Efficacy Scale (FES) was used to evaluate fear of falling. RESULTS: Following six weeks of balance training using the Pedalo equipment, path length and sway velocity in both the eyes open and closed conditions were significantly improved compared with those at baseline (p< 0.05), as well as on BBS, TUG, and FES (p< 0.05). CONCLUSION: Balance training on the Pedalo equipment appears to significantly improve balance in elderly people and reduces their anxiety regarding falls. We conclude that use of such equipment may help elderly people improve their balance and consequently reduce their risk of falling.
Abstract: BACKGROUND: The reproducibility of the HUMAC-NORM isokinetic dynamometer has not yet been established for the muscles around the knee. Previous research suggests practice-based improvement (PBI) may impact upon the reproducibility of isokinetic testing. OBJECTIVE: To investigate test-retest reproducibility of knee flexion and extension isokinetic findings at different velocities, including the influence of familiarisation. METHODS: Seventy physically active, healthy participants with no experience in isokinetic dynamometry performed five repetitions of continuous concentric knee flexion and extension at 60, 120, 180 and 240°/s on four occasions. Peak moment, angle of peak moment, total work and…average power were recorded. Reproducibility was determined using percentage change in the mean, typical error and intraclass correlation coefficients (ICC). RESULTS: For knee flexion and extension, group data met desirable reproducibility criteria for most outcomes and velocities after Trial 2. Within-subject reproducibility generally met acceptable reliabilty criteria after Trial 2 for knee extension, but was predominantly unacceptable for knee flexion. ICC's were acceptable from Trial 2, except for angle of peak moment which did not achieve an acceptable level of reliabilty across any trials, outcomes or velocities. CONCLUSIONS: The HUMAC-NORM demonstrates excellent reproducibility for peak moment, average power and total work parameters for the major knee muscles after one trial. One familiarisation session is recommended prior to testing to minimise the impact of PBI. Additional familiarisation is beneficial when testing individuals, higher velocities and knee flexion.
Keywords: Reproducibility of results, muscle strength dynamometer, practice-based improvement, knee