Isometric Group Research Articles

Fundamental regions for non-isometric group actions

We generalise results about isometric group actions on metric spaces and their fundamental regions to the context of merely continuous group actions. In particular, we obtain results that yield the relative compactness of a fundamental region for a cocompact group action. As a consequence, we obtain a criterion for a cocompact cyclic group of semi-Riemannian homotheties to be inessential.

Isometric vs Isotonic Core Stabilization Exercises to Improve Pain and Disability in Patients with Non-specific Chronic Low Back Pain: A Randomized Controlled Trial.

Non-specific chronic low back pain (NSCLBP) is a prevalent condition that affects 90% of individuals experiencing low back pain. Core stabilization exercises (CSE) stand out as the most commonly employed therapeutic approach for managing NSCLBP. Nevertheless, there remains uncertainty regarding the superior effectiveness between isometric (ISOM) and isotonic (ISOT) types of CSE in the treatment of NSCLBP. The primary objective of this study was to compare the efficacy of ISOM and ISOT exercises concerning pain and disability in patients with NSCLBP. Additionally, the study aimed to assess the effectiveness of both ISOM and ISOT in comparison to no intervention concerning these variables in these patients. This study was a randomized controlled trial that involved 41 men and women experiencing NSCLBP. Participants were randomly allocated to three groups: ISOM CSE (n = 13), ISOT CSE (n = 14), and a waitlist control (n = 14). The exercise training was administered for 40 - 60 minutes three times a week over a period of up to 8 weeks. Pain (assessed using the Visual Analog Scale or VAS) and disability (evaluated through the Oswestry Disability Index or ODI) variables were measured before and after the interventions. Based on the results, there was no significant difference between the 2 exercise groups (ISOM and ISOT) regarding pain and disability. However, the ISOM group demonstrated numerically better results than the ISOT group. Both the ISOM and ISOT groups exhibited a significant decrease in pain levels, with the VAS score decreasing from 5.5 to 2.7 for ISOM and from 5.8 to 3.7 for ISOT, as compared to the control group (P < 0.001 and P = 0.001, respectively). Additionally, the average disability showed a significant improvement in both the ISOM (ODI score from 17 to 11) and ISOT (ODI score from 15.4 to 11) groups compared to the control group (P < 0.001). Both ISOM and ISOT methods are effective in alleviating pain and disability in patients with NSCLBP. However, there is no significant difference in the benefits between them. Numerically, ISOM exercises were found to be superior. Further studies are needed to obtain a more accurate answer regarding their superiority.

Comparison of McKenzie and Isometric Exercises on Neck Functions of Computer Users with Forward Head Posture

Introduction: Prolonged use of computer can lead to poor posture such as forward head posture (FHP). This posture is associated with imbalance and stiffness of the neck muscles, lack of postural awareness and inappropriate ergonomics, resulting in work-related musculoskeletal disorders. These disturbances can affect the performance and productivity of office workers. Postural awareness training, neck exercises, and modalities are interventions in FHP management. Research that compares the effectiveness of cervical McKenzie and isometric exercise on neck functional score in computer users with forward head posture has not been conducted.&#x0D; Methods: This research was a quasi-experimental. The participants, 24 computer users working at Kariadi Hospital, Semarang, were divided into 2 groups by purposive sampling receiving cervical McKenzie exercise (n=12) and cervical isometric exercise (n=12). Each group received different exercise. Neck functional score was assessed by Neck Disability Index (NDI) questionnaire before and after intervention. The mean differences before and after treatment, as well as between groups was compared statistically using paired t-test.&#x0D; Results: The mean NDI score in the McKenzie group after treatment showed an improvement of 7.84 ± 3.54 with p = 0.002. The mean NDI score in the isometric group after treatment also showed an improvement of 3.93 ± 3.75 with p = 0.004. The difference in NDI score improvement in the cervical McKenzie group was greater than the one in isometric group and statistically significant with p = 0.017.&#x0D; Conclusion: Cervical McKenzie exercise was proved to be more effective in improving neck functional scores in patients with FHP compared to cervical isometric exercise.

Comparison of Treatment Outcome of the Effectiveness of Isometric Exercises as Compared to General Exercises with Cervical Spine Mobilization in The Management of Chronic Non Specific Neck Pain

The purpose of this study was to evaluate the “effectiveness of isometric exercises as compared to general exercises along with cervical spinal mobilization to reduce pain, disability and to increase range of motion in chronic non-specific neck pain”For this randomized controlled experiment total 32 patients (16 in each group) with chronic non-specific neck pain were recruited from physiotherapy Ward Mayo Hospital Lahore, Department of Physiotherapy King Edward Medical University Lahore between October, 2019 and March, 2020. Simple randomization method was used to assign participants into isometric exercise group and general exercise with cervical spine mobilization group. The isometric exercise group performed exercises for neck muscle groups with a rubber band and general exercises with cervical mobilization group performed active range of movement exercises for all neck movements. Patients in both groups received 4 supervised treatment sessions per week for 6 weeks. Visual Analogue Scale (VAS), Neck disability index Questionnaire and goniometer were used to assess pain, disability and neck range of movements at baseline and after 6 weeks.Both interventions showed statistically significant improvements in pain, function and range of movement p = 0.001for isometric exercise group, p = 0.05 for general exercises group and p= &lt;0.001 for range of movement. However, mean improvements in post intervention VAS score and Neck disability index Questionnaire score was better in isometric exercises group as compared to general exercise group. In conclusion, both interventions are effective in the treatment of chronic non- specific neck pain however; isometric exercises are clinically more effective than general exercises with cervical spine mobilization.

The Effect of Eccentric or Isometric Training on Strength, Architecture, and Sprinting across an Australian Football Season.

This study aimed to investigate the effect of an isometric (ISO) or Nordic hamstring exercise (NHE) intervention, alongside a sprint training program on hamstring strength, architecture, and sprinting performance in Australian footballers. Twenty-five male athletes undertook NHE ( n = 13) or ISO ( n = 12) training across a 38-wk period (including preseason and in season). Biceps femoris long head (BFlh) architecture, ISO, and eccentric knee flexor strength were assessed at baseline, at the end of preseason (14 wk), and at the conclusion of the intervention. Sprint times and force-velocity profiles were determined at baseline and at the end of preseason. After the intervention, both groups had significant improvements in BFlh fascicle length (NHE: 1.16 cm, 95% CI = 0.68 to 1.63 cm, d = 1.88, P < 0.001; ISO: 0.82 cm, 95% CI = 0.57 to 1.06 cm, d = 1.70, P < 0.001), muscle thickness (NHE: 0.11 cm, 95% CI = 0.01 to 0.21 cm, d = 0.51, P = 0.032; ISO: 0.21 cm, 95% CI = 0.10 to 0.32 cm, d = 0.86, P = 0.002), and eccentric strength (NHE: 83 N, 95% CI = 53 to 114 N, d = 1.79, P < 0.001; ISO: 83 N, 95% CI = 17 to 151 N, d = 1.17, P = 0.018). Both groups also finished the intervention weaker isometrically than they started (NHE: -45 N, 95% CI = -81 to -8 N, d = -1.03, P = 0.022; ISO: -80 N, 95% CI = -104 to -56 N, d = -3.35, P < 0.001). At the end of preseason, the NHE group had improved their 5-m sprint time by 3.3% ± 2.0%), and their maximum horizontal velocity was 3% ± 2.1% greater than the ISO group who saw no changes. Both ISO and NHE training with a periodized sprinting program can increase BFlh fascicle length, thickness, and eccentric strength in Australian footballers. NHE training also improves 5-m sprint time and maximum velocity. However, both interventions reduced ISO strength. These findings provide unique, contextually relevant insights into the adaptations possible in semiprofessional athletes.

KONDROMALAZİ PATELLA TANILI OLGULARDA KUADRİSEPS GÜÇLENDİRİCİ İZOMETRİK VE İZOTONİK EGZERSİZLERİN AĞRI, YAŞAM KALİTESİ VE FONKSİYONEL KAPASİTE ÜZERİNE ÜSTÜNLÜKLERİNİN KARŞILAŞTIRILMASI

Purpose: This study aims to investigate the superiority of different exercise modalities, including isotonic and isometric strengthening for quadriceps, over each other and their effect on pain, quality of life and functional capacity in patients diagnosed with chondromalacia patellae (CMP). &#x0D; Methods: This study was designed as a prospective study in 30 patients(15 patients in isometric, 15 patients in isotonic group) and 15 healthy volunteers aged 20–50 years who were diagnosed with CMP based on physical examination and magnetic resonance imaging and had pain complaints. Pain level was evaluated with Visual Analogue Scala (VAS), functional capacity with Lysholm scale, and quality of life with Short Form-36(SF-36). Q-angle, and thigh circumference were evaluated before and after exercise in all patients. &#x0D; Results: In patients with CMP, there were significant differences in Q-angle, pain, functional capacity, and some subcomponents of the SF-36 quality of life after performing isometric or isotonic exercises compared with the control group (p0,05). In the evaluation of the isotonic and isometric exercise groups, there were no significant difference in the assessment of Q-angle, thigh circumference, pain, functional capacity, and quality of life of patients with CMP (p&gt;0,05).&#x0D; Conclusion: Isometric and isotonic quadriceps strengthening exercises are not superior to each other in terms of pain, functional capacity, and quality of life in CMP treatment.

Isometric group actions with vanishing rate of escape on $$\textrm{CAT}(0)$$ spaces

Isometric group actions with vanishing rate of escape on $$\textrm{CAT}(0)$$ spaces

Some remarks on proper actions, proper metric spaces, and buildings

Abstract We discuss various aspects of isometric group actions on proper metric spaces. As one application, we show that a proper and Weyl transitive action on a euclidean building is strongly transitive on the maximal atlas (the complete apartment system) of the building.

Index of Twisted Elliptic Boundary Value Problems Associated with Isometric Group Actions

Index of Twisted Elliptic Boundary Value Problems Associated with Isometric Group Actions

Trees, length spectra for rational maps via barycentric extensions, and Berkovich spaces

In this paper, we study the dynamics of degenerating sequences of rational maps on Riemann sphere Cˆ using R-trees. As an analogue of isometric group actions on R-trees for Kleinian groups, we give two constructions for limiting dynamics on R-trees: one geometric and one algebraic. The geometric construction uses the limit of rescalings of barycentric extensions of rational maps, while the algebraic construction uses the Berkovich space of complexified Robinson’s field. We show that the two approaches are equivalent. As an application, we use it to give a classification of hyperbolic components of rational maps that admit degeneracies with bounded multipliers.

Comparison of time-dependent resistance isometric exercise and active range of motion exercise in alleviating the sensitization of postoperative axial pain after cervical laminoplasty

BackgroundPostoperative axial pain (PAP) is a significant complication after cervical laminoplasty. ObjectiveTo investigate pain sensitization in PAP patients and effects of time-dependent resistance isometric exercise compared to active range-of-motion exercise on PAP. Study designRetrospective cohort analysis. Methods211 patients undergoing postoperative 12-week exercises were evaluated for pressure pain threshold (PPT), temporal summation (TS) and both cross-sectional area and fatty infiltration of paraspinal muscles preoperatively and 3 months postoperatively. There patients underwent Numeric rating pain scale (NRS) and neck disability index (NDI) 3 and 6 months postoperatively. ResultsAt postoperative 3-month assessments, fewer patients undergoing isometric exercise showed PAP compared to range-of-motion exercise group (14/98 vs. 34/113; P = 0.006), and pain-related assessments in the former were lower than the latter (NRS at rest: 0.3 ± 0.8 vs. 0.7 ± 1.4, P = 0.014; NRS with movements: 0.4 ± 1.0 vs. 1.0 ± 1.7, P = 0.015; NDI: 2.4 ± 6.3 vs. 6.7 ± 10.9, P = 0.002). Postoperative cross-sectional area was smaller in isometric exercise group (603.5 ± 190.2) than in range-of-motion exercise group (678.7 ± 215.5) (P = 0.033), and the former showed higher local-area PPT and lower TS than the latter (PPT: 3.9 ± 1.8 vs. 3.1 ± 1.6, P = 0.002; TS: 1.8 ± 0.9 vs. 2.2 ± 1.0, P = 0.003). PAP patients showed lower local-area PPT and greater TS than those without PAP in both isometric (PPT: 2.8 ± 0.7 vs. 4.0 ± 1.9, P = 0.019; TS: 2.4 ± 0.6 vs. 1.7 ± 0.9, P = 0.011) and range-of-motion (PPT: 2.2 ± 0.9 vs. 3.6 ± 1.7, P < 0.001; TS: 2.8 ± 0.8 vs. 1.9 ± 0.9, P < 0.001) exercise groups. ConclusionsBoth peripheral and central sensitization are involved in PAP. Time-dependent isometric exercise has more positive effects on PAP than range-of-motion exercise because of its advantages in improving pain sensitization.

Effects of Isometric and Isotonic Training on Health-Related Fitness Components in Young Adults

Isometric and isotonic exercises are important modes of resistance training for enhancement of athletic performance. However, less is known about their effects on fitness and health in recreationally physically active individuals. This study evaluates the effect of isometric and isotonic training protocols on health-related fitness components in young university students. A group of one hundred males (18–24 years) underwent a 12-week isotonic and isometric training program (two days per week, 45 min per session). They were randomized into two groups, group A (n = 50) and group B (n = 50). While group A underwent the isotonic resistance training, the group B completed isometric resistance training. Prior to and after training programs, body mass index (BMI) was measured and the bench press 1RM test, sit-ups test, sit and reach test, and 12 min run/walk test were performed. Results showed significant improvements in BMI, bench press 1RM test, sit-ups test, sit and reach test, and 12 min run/walk test after both isotonic and isometric training protocols. The isotonic training group increased in BMI by 2.70%, bench press 1RM by 34.45%, number of sit-ups by 24.13%, sit and reach distance by 29.12%, and 12 min run/walk distance by 19.82%. Isometric training group increased in BMI by 1.96%, bench press 1RM by 14.23%, number of sit-ups by 7.80%, sit and reach distance by 6.92%, and 12 min run/walk distance by 6.99%. A comparison of these training protocols revealed that the isotonic group improved significantly more than the isometric group in the bench press 1RM (20.22%), number of sit-ups (16.33%), and sit and reach distance (22.2%) but not in the 12 min run/walk distance (12.83%) and BMI (0.74%). These findings indicate that both isotonic and isometric resistance training protocols improve health-related fitness components in young adults; however isotonic training is more efficient than isometric training in increasing their muscle strength, muscular endurance, and flexibility.

Comparison of the Effects of Isokinetic, Isometric, and Isotonic Exercises on Knee Osteoarthritis Using Ultrasound.

Introduction: This study aims to investigate the effects of different types of exercise on pain, functional capacity, muscle strength measured by an isokinetic dynamometer, and femoral cartilage (FC) thickness measured using ultrasound in patients with knee osteoarthritis (KOA).Methods: Sixty patients were randomized to isokinetic, isometric, and isotonic exercise groups, and exercise programs were completed five days a week over three weeks. The FC thickness for each knee was evaluated in medial, intercondylar, and lateral areas using ultrasound, and muscle strength was assessed by an isokinetic dynamometer. Activity levels were also measured using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). At three weeks from baseline, follow-up clinical measurements of knee muscle strength and FC thickness were performed.Results: A significant decrease was observed in all three groups in post-treatment visual analog scale (VAS) pain scores. In terms of evaluation of WOMAC scores, no significant difference was observed between the groups. In the isokinetic group, a significant increase was detected in extensor and flexor muscle strength measurements at the angular velocities of 60º/s and 180º/s. In the isotonic group, a statistically significant increase was detected in peak torque values of extensor and flexor muscles at 60º/s in the left knee only. Regarding FC thickness, a significant increase was found in the intercondylar area and the lateral condyle measurements of the left knee in the isokinetic group and the intercondylar area measurements of the right knee in the isometric group. In the isokinetic group, a statistically significant decrease was detected in the medial condyle of the right knee. It was observed that isokinetic exercise ended up with a significant increase in FC thickness in the intercondylar area and the lateral condyle of the left knee and a significant decrease in the medial condyle of the right knee.Conclusion: Isokinetic exercise is functionally superior to isometric and isotonic exercise, providing more significant improvements in muscle strength measurements and FC thickness. Further research is needed to determine the interactions among therapeutic exercises in patients with KOA that impact knee cartilage quantities.

Effect of an Isometric or Eccentric Hip Extension Exercise Intervention on Hamstring Strength, Architecture, and Morphology.

This study aimed to investigate hamstring architectural, strength, and morphological adaptations after an eccentric or isometric hip extension exercise intervention. Twenty-four recreationally active males performed either an eccentric ( n = 12) or an isometric hip extension ( n = 12) exercise intervention, twice per week for 6 wk, followed by a 4-wk detraining period. Biceps femoris long head (BFlh) architecture was assessed pre-intervention, mid-intervention, post-intervention, and post-detraining via two-dimensional ultrasound. Strength was assessed pre-intervention, post-intervention, and post-detraining during an isokinetic knee flexion, an isometric hip extension, a Nordic hamstring exercise, and a single-leg hamstring bridge repetition to fatigue test. Hamstring muscle morphology was assessed via magnetic resonance imaging before strength testing sessions. The eccentric hip extension exercise intervention significantly lengthened BFlh fascicles (+19.7%, P < 0.001, d = 1.57), increased eccentric knee flexion torque (ECC 60°·s -1 , +12%, P < 0.005, d = 0.66; ECC 180°·s -1 , +8.3%, P < 0.05, d = 0.41), and increased BFlh (+13.3%, P < 0.001, d = 1.96) and semimembranosus (SM) muscle volume (+12.5%, P < 0.001, d = 2.25). After 4 wk of detraining, BFlh fascicles were significantly shortened in the eccentric group (-14.8%, P < 0.005, d = -1.25), whereas eccentric knee flexion torque and BFlh and SM volumes were unchanged. The isometric hip extension exercise intervention significantly increased isometric knee flexion torque (+10.4%, P < 0.05, d = 0.54), isometric hip extension force (+12.4%, P < 0.05, d = 0.41), and semitendinosus volume (+15%, P = 0.054, d = 1.57). All other outcome measures saw no significant changes. After 4 wk of detraining, no significant changes to any variables were observed in the isometric group. The eccentric but not isometric hip extension exercise intervention significantly increased BFlh fascicle length. Both exercise interventions demonstrated contraction mode-specific increases in strength. However, the eccentric hip extension exercise intervention resulted in preferential hypertrophy of BFlh and SM, and the isometric hip extension exercise intervention led to selective hypertrophy of semitendinosus.

Profile decomposition in Sobolev spaces and decomposition of integral functionals I: Inhomogeneous case

The present paper is devoted to analyzing the lack of compactness of bounded sequences in inhomogeneous Sobolev spaces, where bounded sequences might fail to be compact due to an isometric group action, that is, translation. It will be proved that every bounded sequence (un) has (possibly infinitely many) profiles, and then the sequence is asymptotically decomposed into a sum of translated profiles and a double-suffix residual term, where the residual term becomes arbitrarily small in appropriate Lebesgue or Sobolev spaces of lower order. To this end, functional analytic frameworks are established in an abstract way by making use of a group action G, in order to characterize profiles by (un) with G. One also finds that a decomposition of the Sobolev norm into profiles is bounded by the supremum of the norm of un. Moreover, the profile decomposition leads to results of decomposition of integral functionals of subcritical order. It is noteworthy that the space where the decomposition of integral functionals holds is the same as that where the residual term is vanishing.

Effect of post-isometric relaxation versus myofascial release therapy on pain, functional disability, rom and qol in the management of non-specific neck pain: a randomized controlled trial

BackgroundNon-specific neck pain is the most prevailing musculoskeletal disorder which has a large socioeconomic burden worldwide. It is associated with poor posture and neck strain which may lead to pain and restricted mobility. Physical therapists treat such patients through several means. Post isometric relaxation and Myofascial release therapy are used in clinical practice with little evidence to be firmed appropriately. So, this study was conducted to explore the effect of Post-isometric relaxation in comparison to Myofascial release therapy for patients having non-specific neck pain.MethodologySixty patients were randomly allocated to Post isometric group and the Myofascial group. The treatment period was of 2 weeks. All the patients were evaluated using the Visual analogue scale (VAS), Neck disability index (NDI), Universal Goniometer, and WHO BREF Quality of life-100 in the 1st and 6th sessions. Recorded data was entered on SPSS 21. Data were examined using two-way repeated ANOVA to measure the variance of analysis (group x time).ResultsAnalysis of the baseline characteristics revealed that both groups were homogenous in terms of age and gender i.e. a total of 60 participants were included in this research study 30 in each group. Out of 60 patients, there were 20(33.3%) males and 40(66.7%) females with a mean age of 32.4(5.0) years. Participants in the Post Isometric group demonstrated significant improvements (p < 0.025) in VAS, NDI, Cervical Extension, left side rotation ranges, and QoL (Social Domain) at the 2-week follow-up compared with those in the Myofascial group. In addition, the Myofascial group indicated significantly better improvement in the mean score of CROM (flexion and right and left side bending).ConclusionThe study demonstrated patients with nonspecific neck pain can benefit from the post isometric relaxation with significant improvement in pain, disability, cervical ROM, and Quality of life compared with myofascial release therapy.Trial registrationClinical Trial registered on clinicaltrial.gov (NCT number) NCT04638062, 20/11/2020 (prospectively registered).

Existence results for the mean field equation on a closed symmetric Riemann surface

Let (S,g) be a closed Riemann surface, G be a finite isometric group acting on it and ♯G(x) be the number of all distinct points in the set G(x) for x∈S. If there exists some ℓ∈N⁎ satisfying ♯G(x)≡ℓ for all x∈S, then we show that for any ρ∈(8πkℓ,8π(k+1)ℓ) with k∈N⁎, the mean field equationΔgu=ρ(heu∫Sheudvg−1|S|) has a G-invariant solution, where h is a strictly positive and G-invariant smooth function. Our method is a modification of the min-max scheme due to Ding-Jost-Li-Wang (1999), Djadli-Malchiodi (2008) and Djadli (2008).

Improved Trudinger–Moser inequality involving Lp-norm on a closed Riemann surface with isometric group actions

In this paper, using the method of blow-up analysis, the authors obtain an improved Trudinger–Moser inequality involving [Formula: see text]-norm ([Formula: see text]) and prove the existence of its extremal function on a closed Riemann surface [Formula: see text] with the action of a finite isometric group [Formula: see text]. To be exact, let [Formula: see text] be the usual Sobolev space, a function space [Formula: see text] and [Formula: see text] [Formula: see text] and [Formula: see text] where [Formula: see text] stands for the number of all distinct points in the set [Formula: see text]. Define [Formula: see text], where [Formula: see text] is the standard [Formula: see text]-norm on [Formula: see text]. Using blow-up analysis, we prove that if [Formula: see text], the supremum [Formula: see text] and this supremum can be attained; if [Formula: see text], the above supremum is infinite. This kind of inequality will play an important role in the study of prescribing Gaussian curvature problem and mean field equations. In particular, their result generalizes those of Chen [A Trudinger inequality on surfaces with conical singularities, Proc. Amer. Math. Soc. 108 (1990) 821–832], Yang [Extremal functions for Trudinger–Moser inequalities of Adimurthi–Druet type in dimension two, J. Differential Equations 258 (2015) 3161–3193] and Fang–Yang [Trudinger–Moser inequalities on a closed Riemannian surface with the action of a finite isometric group, Ann. Sc. Norm. Super. Pisa Cl. Sci. 20 (2020) 1295–1324].

A mean field type flow with sign-changing prescribed function on a symmetric Riemann surface

Let (Σ,g) be a closed Riemann surface, and G={σ1,⋯,σN} be a finite isometric group acting on it. Denote a positive integer ℓ=minx∈Σ⁡I(x), where I(x) is the number of all distinct points of the set {σ1(x),⋯,σN(x)}. In this paper, we consider the following G-invariant mean field type flow{∂∂teu=Δgu+8πℓ(feu∫Σfeudvg−1|Σ|)u(⋅,0)=u0, where u0 belongs to C2+α(Σ) for some α∈(0,1), f is a sign-changing smooth function such that ∫Σfeu0dvg≠0, both u0 and f are G-invariant, and |Σ| denotes the area of (Σ,g). Such kind of flow was originally proposed by Castéras [6]. Through a priori estimates, we prove that the flow u(x,t) exists for all time t∈[0,∞). Moreover, by employing blow-up procedure, we obtain that under certain geometric conditions, u(x,t) converges to u(x) in H2(Σ) as t→∞, where u(x) is a solution of the mean field equation−Δgu=8πℓ(feu∫Σfeudvg−1|Σ|). This generalizes recent results of Li-Zhu [27] and Sun-Zhu [37].

Effect of daily 3-s maximum voluntary isometric, concentric, or eccentric contraction on elbow flexor strength.

The present study compared a 3-s isometric maximal voluntary contraction (MVC), concentric MVC and eccentric MVC of the elbow flexors performed daily for 5days a week for 4weeks for changes in muscle strength and thickness. Young sedentary individuals were assigned to one of three training groups (n=13 per group) that performed either 3-s isometric, concentric, or eccentric MVC once a day for 20days, or to a control group (n=10) that had measurements without training. The participants in the isometric group performed isometric MVC at 55° (0.96rad) elbow flexion, and those in the concentric or eccentric group performed concentric MVC or eccentric MVC between 10° (0.17rad) and 100° (1.75rad) elbow flexion at 30°/s (0.52rad/s) on an isokinetic dynamometer. MVC isometric torque at 20° (0.35rad), 55° (0.96rad), and 90° (1.57rad) elbow flexion, MVC concentric and eccentric torque at 30°/s (0.52rad/s) and 180°/s (3.14rad/s), and muscle thickness (MT) of biceps brachii and brachialis were measured before and several days after the 20th exercise session. The control group did not show any changes. The eccentric group showed increases (p<0.01) in isometric (three angle average: 10.2±6.4%), concentric (two velocity average: 12.8±9.6%), and eccentric MVC torque (12.2±7.8%). An increase (p<0.05) was limited for isometric MVC torque (6.3±6.0%) in the concentric group, and for eccentric MVC torque (7.2±4.4%) in the isometric group. No significant changes in MT were evident for all groups. Performing one 3-s MVC a day increased muscle strength, but eccentric MVC produced more potent effects than isometric or concentric MVC.