scholarly journals Velocity-specific knee strength between professional and under-17 female volleyball player

2019 ◽  
Vol 75 (1) ◽  
Author(s):  
Alexandre R.M. Pelegrinelli ◽  
Laís F. Dela Bela ◽  
Mariana F. Silva ◽  
Lucas C.R. Rodrigues ◽  
João P. Batista ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Knee Extensor ◽  
Peak Torque ◽  
Total Work ◽  
Flexor Muscle ◽  
Mean Power ◽  
Cross Sectional ◽  
Significant Group ◽  
Surface Maps ◽  
Volleyball Players

Background: Many studies have investigated isokinetic performance in volleyball players but not through surface maps.Objectives: The goals of this study were to assess velocity-specific isokinetic knee extensor–flexor muscle strength and to compare the isokinetic knee extensor–flexor muscles between professional (PRO) and under-17 (U17) female volleyball players.Method: This cross-sectional laboratory study was developed with two groups: PRO (n = 12), medianage = 21.3 years, and U17 (n = 9), medianage = 15 years. Peak torque, total work, mean power, angle of peak torque, hamstring–quadriceps torque ratio (H–Q ratio) and torque–angle–velocity surface maps were analysed from knee extension–flexion at 60, 120 and 300 degrees per second (°/s).Results: Significant differences were identified for extensor peak torque between PRO x = 202.3 Newton metre (N·m) (standard deviation [SD] = 24.4) and U17 x = 141.6 N·m (30.1) at 60 °/s (p < 0.001; d = 2.21) as well as flexor peak torque (PRO x = 75.7 N·m [10.3] and U17 x = 57.7 N·m [11.4]) at 120 °/s (p < 0.001; d = 1.65) for the dominant limb. There were also significant group differences for total work and mean power at all velocities for extension and flexion. Surface maps demonstrated higher torque at lower speeds for both groups with smaller torque changes across velocities for flexion.Conclusion: Different groups of female volleyball players showed contrasting concentric knee muscle strength across isokinetic velocities.Clinical implications: These results demonstrate the importance of specific strength training for different age groups, even within the same sport, and provide insight into muscle strength.

scholarly journals Associations of the Stair Climb Power Test With Muscle Strength and Functional Performance in People With Chronic Obstructive Pulmonary Disease: A Cross-Sectional Study

2010 ◽  
Vol 90 (12) ◽  
pp. 1774-1782 ◽  
Author(s):  
Marc Roig ◽  
Janice J. Eng ◽  
Donna L. MacIntyre ◽  
Jeremy D. Road ◽  
W. Darlene Reid
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Muscle Strength ◽  
Functional Performance ◽  
Knee Extensor ◽  
Chronic Obstructive ◽  
Flexor Muscle ◽  
Cross Sectional ◽  
Obstructive Pulmonary Disease ◽  
Power Test ◽  
Muscle Torque

Background The Stair Climb Power Test (SCPT) is a functional test associated with leg muscle power in older people. Objective The purposes of this study were to compare the results of the SCPT in people with chronic obstructive pulmonary disease (COPD) and people who were healthy and to explore associations of the SCPT with muscle strength (force-generating capacity) and functional performance. Design The study was a cross-sectional investigation. Methods Twenty-one people with COPD and a predicted mean (SD) percentage of forced expiratory volume in 1 second of 47.2 (12.9) and 21 people who were healthy and matched for age, sex, and body mass were tested with the SCPT. Knee extensor and flexor muscle torque was assessed with an isokinetic dynamometer. Functional performance was assessed with the Timed “Up & Go” Test (TUG) and the Six-Minute Walk Test (6MWT). Results People with COPD showed lower values on the SCPT (28%) and all torque measures (∼32%), except for eccentric knee flexor muscle torque. In people with COPD, performance on the TUG and 6MWT was lower by 23% and 28%, respectively. In people with COPD, the SCPT was moderately associated with knee extensor muscle isometric and eccentric torque (r≥.46) and strongly associated (r=.68) with the 6MWT. In people who were healthy, the association of the SCPT with knee extensor muscle torque tended to be stronger (r≥.66); however, no significant relationship between the SCPT and measures of functional performance was found. Limitations The observational design of the study and the use of a relatively small convenience sample limit the generalizability of the findings. Conclusions The SCPT is a simple and safe test associated with measures of functional performance in people with COPD. People with COPD show deficits on the SCPT. However, the SCPT is only moderately associated with muscle torque and thus cannot be used as a simple surrogate for muscle strength in people with COPD.

Hamstring Flexibility Is Not Correlated with Isokinetic Knee Muscle Strength in Female Modern Dancers

2018 ◽  
Vol 33 (2) ◽  
pp. 95-101 ◽  
Author(s):  
Ani Agopyan
Keyword(s):  
Muscle Strength ◽  
Knee Extensor ◽  
Peak Torque ◽  
Flexor Muscle ◽  
Work Production ◽  
University Level ◽  
Modern Dancers ◽  
Hamstring Flexibility ◽  
Knee Muscle ◽  
The Right

OBJECTIVE: To evaluate bilateral isokinetic knee extensor and flexor muscle strength relative to hamstring flexibility in female modern dancers. METHODS: 20 trained university-level female modern dance students (mean age 23.8±3.8 yrs) volunteered for the study. Concentric isokinetic peak torque (PT, in Nm), peak torque % of body weight (PT%BW, in Nm/kg), and total work (TW, in J) of the knee extensor and flexor muscles for each leg were measured with a dynamometer at a velocity of 60, 180, and 300°/s. Hamstring flexibility of both limbs was assessed by a goniometer with the subjects in a supine position using the active straight leg raise (SLR) test. Participants were divided into flexible (n=10) and highly flexible (n=10) groups based on their hamstring flexibility. RESULTS: The flexible and highly flexible groups had significant differences (p≤0.05) for the right (flexible, 119.7±4.3°; highly flexible, 137.7±2.6°) and left active SLR tests (flexible, 120.6±5.3°; highly flexible, 138.3±4.5°). No significant differences were found between the flexible and highly flexible dancers for concentric knee extensor and flexor muscle strength in all selected parameters (p≤0.05). There were also no significant correlations between flexibility and bilateral PT, PT%BW, and TW scores (60, 180, and 300°/s) of dancers at the concentric contraction (p≤0.05). CONCLUSION: These findings indicate that hamstring flexibility (for both the flexible and highly flexible groups) is not correlated with knee strength and has no impact on torque and work production during maximal concentric isokinetic knee muscle action in university-level female modern dancers.

scholarly journals Muscle strength, size and composition following 12 months of gender-affirming treatment in transgender individuals: retained advantage for the transwomen

2019 ◽  
Author(s):  
A Wiik ◽  
TR Lundberg ◽  
E Rullman ◽  
DP Andersson ◽  
M Holmberg ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Muscle Mass ◽  
Sex Hormones ◽  
Hormone Replacement ◽  
Knee Extensor ◽  
Hormone Treatment ◽  
Muscle Volume ◽  
Thigh Muscle ◽  
Flexor Muscle ◽  
Cross Sectional

AbstractObjectivesThis study explored the effects of gender-affirming treatment, which includes inhibition of endogenous sex hormones and replacement with cross-sex hormones, on muscle function, size and composition in 11 transwomen (TW) and 12 transmen (TM).MethodsIsokinetic knee extensor and flexor muscle strength was assessed at baseline (T00), 4 weeks after gonadal suppression of endogenous hormones but before hormone replacement (T0), and 3 (T3) and 11 (T12) months after hormone replacement. In addition, at T00 and T12, we assessed lower-limb muscle volume using MRI, and cross-sectional area (CSA) and radiological density using CT.ResultsThigh muscle volume increased (15%) in TM, which was paralleled by increased quadriceps CSA (15%) and radiological density (6%). In TW, the corresponding parameters decreased by −5% (muscle volume) and −4% (CSA), while density remained unaltered. The TM increased strength over the assessment period, while the TW generally maintained or slightly increased in strength. Baseline muscle volume correlated highly with strength (R>0.75), yet the relative change in muscle volume and strength correlated only moderately (R=0.65 in TW and R=0.32 in TM). The absolute levels of muscle volume and knee extension strength after the intervention still favored the TW.ConclusionCross-sex hormone treatment markedly affects muscle strength, size and composition in transgender individuals. Despite the robust increases in muscle mass and strength in TM, the TW were still stronger and had more muscle mass following 12 months of treatment. These findings add new knowledge that could be relevant when evaluating transwomen’s eligibility to compete in the women’s category of athletic competitions.

scholarly journals Effect of long-term training adaptation on isokinetic strength in college male volleyball players

2019 ◽  
Vol 23 (5) ◽  
pp. 236-241
Author(s):  
A. Kafkas ◽  
M.E. Kafkas ◽  
S. Savaş
Keyword(s):  
Resistance Training ◽  
Muscle Strength ◽  
Knee Extensor ◽  
Isokinetic Strength ◽  
Flexor Muscle ◽  
Knee Strength ◽  
Volleyball Players ◽  
Angular Velocities ◽  
Knee Muscle ◽  
Flexor Strength

Background and Study Aim: Most of this study focused on endurance, power, and anthropometric measurements but no research declared isokinetic strength changes during two years. The purpose of this study was to assess the effect of resistance exercises on two seasonal alters in isokinetic strength of knee muscles at different angular velocities, in college volleyball players. Material and Methods: Thirteen college volleyball players, (age: 21.75 years, body mass: 78.60 kg, and height: 187.0 cm) participated in the study. All college volleyball players take part in the two-year (8 month each year) volleyball-specific training and competitions. The measurement of peak isokinetic concentric knee extension and knee flexion torque in both legs were taken at 2 angular velocities of movement, low at 60° s-1, and intermediate at 180° s-1. Results: The pre- and post-test values of the peak isokinetic strength found that statistical significance difference, at 60° s-1 and 180° s-1 for knee extensor-flexor both dominant and non-dominant in favor of post-tests. Significant enhances were observed in the baseline dominant knee extensor-flexor muscle strength (extensor knee strength 60° s-1: 19.0%, 180° s-1: 20.5%, flexor knee strength, 60° s-1: 33.4%, 180° s-1: 31.4%) respectively. Non-dominant knee extensor-flexor muscle strength increased significantly over the two-year period (extensor knee strength 60° s-1: 21.3%, 180° s-1: 23.0%, flexor knee strength, 60° s-1: 37.4%, 180° s-1: 33.9%) respectively. Conclusion: As a result, our data suggests that the two-year planned program of specific volleyball and resistance training can increase the knee muscle extensor-flexor strength and H:Q ratios of volleyball players. Especially, at a 60° s-1 and 180° s-1 angular velocities, whilst the knee muscle extensor-flexor strength and H:Q ratios for dominant and non-dominant legs were increasing, also H:Q ratios disproportion were decreasing. Therefore, these alters indicated that regular specific-volleyball and resistance training can increase knee muscle extensor-flexor strength and H:Q ratios for dominant and non-dominant legs.

Effects of Short-Term Resistance Training on Muscle Strength and Morphology in the Elderly

2000 ◽  
Vol 8 (4) ◽  
pp. 312-324 ◽  
Author(s):  
David E.T. O’Neill ◽  
Robert E. Thayer ◽  
Albert W. Taylor ◽  
Tomasz M. Dzialoszynski ◽  
Earl G. Noble
Keyword(s):  
Resistance Training ◽  
Fiber Type ◽  
Knee Extensor ◽  
Peak Torque ◽  
The Elderly ◽  
Type I ◽  
Fiber Types ◽  
Short Term ◽  
Mean Power ◽  
Cross Sectional

Ten moderately active participants (8 women, 2 men; mean age 66.3 ± 1.2 years), engaged in 8 weeks of isotonic knee-extensor resistance training. Afterward, peak torque output (180°/s) and mean power increased 30.8% and 27.2%, respectively, in the experimental limb (EL). A moderate, nonsignificant cross-over training effect was observed in the contralateral untrained limb (CL) for the same measures. Whereas mean fiber cross-sectional area (CSA) was unaltered in the CL by training. Fiber Types I and lib in the EL displayed increased CSA. However, mean CSAs for all fiber types in the trained EL were no larger (p > .05) than those observed in the CL before or after training. There were no significant changes in muscle-fiber-type composition, the proportion of Type I myosin heavy chain, or Type Ha CSA. These data suggest that short-term resistance training can significantly increase isokinctic peak torque in the elderly, with minimal changes in the histochemical and biochemical parameters examined.

scholarly journals Pre- and Post-Operative Limb Symmetry Indexes and Estimated Preinjury Capacity Index of Muscle Strength as Predictive Factors for the Risk of ACL Reinjury: A Retrospective Cohort Study of Athletes after ACLR

2021 ◽  
Vol 11 (8) ◽  
pp. 3498
Author(s):  
Martin Rudolf Zore ◽  
Nevenka Kregar Velikonja ◽  
Mohsen Hussein
Keyword(s):  
Muscle Strength ◽  
Cruciate Ligament ◽  
Knee Extensor ◽  
Peak Torque ◽  
Secondary Injury ◽  
Flexor Muscle ◽  
Acl Injuries ◽  
Secondary Injuries ◽  
Operative Limb ◽  
Torque Values

Long-term muscle weakness may increase the risk of knee reinjury after anterior cruciate ligament reconstruction (ACLR) and of osteoarthritis. The incidence of secondary injuries after ACLR and the predictive value of preoperative and postoperative limb symmetry index (LSI) and estimated preinjury capacity (EPIC) index were studied for predicting the risk of reinjury in a retrospective study. Sixty-three recreational and professional athletes after ACLR with hamstring autograft were followed for secondary injury in the period from 2012 to 2014, 5 years after ACLR. Peak torque values of knee extensor and flexor muscle strength of the involved and uninvolved limb were measured with an isokinetic dynamometer at 60 degrees per second before ACLR and 6 months after ACLR and were used to calculate LSI and EPIC index. The results suggest that the preoperative LSI and EPIC indexes predict a secondary ACL injury better than the postoperative LSI for extensor muscles which is often used as a criterion to determine the time for returning to normal sports activities. Individuals with secondary ACL injuries suffer greater loss of knee extensor muscle strength of the uninvolved limb between preoperative and postoperative ACLR testing compared to the individuals without secondary injury.

Isokinetic Strength After ACL Reconstruction: Influence of Concomitant Anterolateral Ligament Reconstruction

2021 ◽  
pp. 194173812110054
Author(s):  
Benoit Gillet ◽  
Yoann Blache ◽  
Isabelle Rogowski ◽  
Grégory Vigne ◽  
Bertrand Sonnery-Cottet ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Ligament Reconstruction ◽  
Knee Extensor ◽  
Anterolateral Ligament ◽  
Flexor Muscle ◽  
Knee Flexor ◽  
Strength Recovery ◽  
Flexor Muscles ◽  
Knee Muscle ◽  
Knee Muscle Strength

Background: To reduce the rate of anterior cruciate ligament (ACL) graft rupture, recent surgeries have involved anterolateral ligament reconstruction (ALLR). This reconstruction procedure harvests more knee flexor muscle tendons than isolated ACL reconstruction (ACLR), but its influence on knee muscle strength recovery remains unknown. This study aimed to assess the influence of ALLR with a gracilis graft on the strength of the knee extensor and flexor muscles at 6 months postoperatively. Hypothesis: The additional amount of knee flexor harvest for ALLR would result in impairment in knee flexor muscle strength at 6 months postoperatively. Study Design: Retrospective cohort study. Level of Evidence: Level 2. Methods: A total of 186 patients were assigned to 2 groups according to the type of surgery: ACL + ALLR (graft: semitendinosus + gracilis, n = 119) or isolated ACLR (graft: semitendinosus, n = 67). The strength of the knee extensor and flexor muscles was assessed using an isokinetic dynamometer at 90, 180, and 240 deg/s for concentric and 30 deg/s for eccentric contractions and compared between groups using analysis of variance statistical parametric mapping. Results: Regardless of the surgery and the muscle, the injured leg produced significantly less strength than the uninjured leg throughout knee flexion and extension from 30° to 90° for each angular velocity (30, 90, 180, and 240 deg/s). However, the knee muscle strength was similar between the ACL + ALLR and ACLR groups. Conclusion: The addition of ALLR using the gracilis tendon during ACLR does not alter the muscle recovery observed at 6 months postoperatively. Clinical Relevance: Although more knee flexor muscle tendons were harvested in ACL + ALLR, the postoperative strength recovery was similar to that of isolated ACLR.

The Effects of Tourniquet Application in Total Knee Arthroplasty on the Recovery of Thigh Muscle Strength and Clinical Outcomes

2020 ◽  
Author(s):  
Omer Ayik ◽  
Mehmet Demirel ◽  
Fevzi Birisik ◽  
Ali Ersen ◽  
Halil I. Balci ◽  
...  
Keyword(s):  
Total Knee Arthroplasty ◽  
Muscle Strength ◽  
Clinical Outcomes ◽  
Knee Arthroplasty ◽  
Peak Torque ◽  
Thigh Muscle ◽  
Controlled Study ◽  
Total Work ◽  
Isokinetic Muscle Strength ◽  
Total Knee

AbstractThe present randomized controlled study aims to evaluate whether tourniquet application during total knee arthroplasty (TKA) has an effect on (1) thigh muscle strength (quadriceps and hamstring muscle strength) and (2) clinical outcomes (postoperative knee range of motion [ROM], postoperative pain level, and Knee Society Score [KSS]). The effects of tourniquet application during TKA were investigated in 65 patients randomly allocated to one of two groups: TKA with a tourniquet and TKA without a tourniquet. Patients in both groups were comparable in terms of the demographic and clinical data (p > 0.05 for age, number of patients, sex, radiographic gonarthrosis grade, American Society of Anesthesiologists [ASA] classification, and body mass index [BMI]). All patients in both groups were operated by the same surgeon using one type of prosthesis. Isokinetic muscle strength (peak torque and total work) of knee extensors (quadriceps) and flexors (hamstrings) was measured in Newton meters (Nm) using a CYBEX 350 isokinetic dynamometer (HUMAC/CYBEX 2009, Stoughton, MA). The combined KSS (knee score + function score), visual analog scale (VAS), and knee ROM were measured preoperatively and at 1 and 3 months postoperatively to evaluate clinical outcomes. There were no significant differences between the two groups in preoperative and postoperative values of isokinetic muscle strength (peak torque and total work) and aforementioned clinical outcomes (p < 0.05). The present study has shown that quadriceps strength and clinical outcomes were not improved in the early postoperative period (3 months) when a tourniquet was not used during TKA.

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