Isokinetic Knee Muscle Strength Research Articles

A Pilot Study on the Efficacy of an App-Based Rehabilitation Counselling Program after Total Knee Arthroplasty.

The aim of this study was to determine the effects of a novel app-based rehabilitation counselling program in patients recovering from total knee arthroplasty. In the app-based rehabilitation counselling program, a counselor provides one-on-one rehabilitation exercises and management-focused psychological counselling after total knee arthroplasty (TKA). This study included 42 patients, who were divided into three groups of 14 patients each: Group A, whose rehabilitation training was based on a guideline leaflet; Group B, whose rehabilitation was based on the app-based rehabilitation counselling program; and Group C, whose rehabilitation training was based on continuous passive motion combined with the app-based rehabilitation counselling program. To determine the effects of rehabilitation, the isokinetic knee muscle strength and knee joint range of motion were measured in addition to knee function tests such as the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the visual analogue scale (VAS) for pain at two and three months after rehabilitation. The comparison of the means of the three groups was analyzed using one-way analysis of variance (ANOVA), with Group C showing significant variance in isokinetic knee muscle strength (p < 0.05), passive ROM (p < 0.01), and WOMAC (p < 0.05) after three months. As a result, this study confirmed the positive potential of the app-based rehabilitation counselling program.

Isokinetic Knee Muscle Strength Parameters and Anthropometric Indices in Athletes with and without Hyperextended Knees.

Background and Objectives: Hypermobility has been linked to decreased knee performance, including isokinetic and isometric knee strength. This study aimed to determine whether athletes with and without knee hyperextension have different hamstring-to-quadriceps strength (H/Q) ratios and to investigate the associations between knee hyperextension indices and H/Q ratios and anthropometric characteristics. Materials and Methods: The sample consisted of 47 healthy male athletes without knee injuries aged 23.48 ± 3.54 years. The variables included the degree of knee hypermobility, isokinetic parameters of the leg musculature, and anthropometric indices. Differences between athletes with and without hyperextension were calculated using an independent sample t-test, effect sizes, and discriminant analysis, while associations between the variables were checked by Pearson's correlation coefficient and multiple regression analysis. Results: Athletes with hyperextended knees had shorter legs (t value = -2.23, p = 0.03, moderate ES) and shins (t = -2.64, p = 0.01, moderate ES) and a lower H/Q ratio at an angular velocity of 60°/s (t = -2.11, p = 0.04, moderate ES) than those in the nonhyperextended group did; these differences were supported by discriminant analysis (Wilks' L = 0.60, p = 0.01). An increase in the H/Q ratio at an angular velocity of 60°/s was associated with the degree of knee hypermobility (R = -0.29, p = 0.04). Conclusions: This research showed that athletes with knee hypermobility have weaker hamstring strength and thus a lower H/Q strength ratio at lower angular velocities. These findings suggest that targeted strength training programs for leg (i.e., hamstrings) muscles should help individuals with knee hypermobility.

Effectiveness and mechanism of action of rTMS combined with quadriceps strength training in individuals with knee osteoarthritis: study protocol for a randomized controlled trial

BackgroundQuadriceps training is necessary in function and activity of daily living for patients with knee osteoarthritis (KOA). However, it did not reduce the rate of surgical treatment for end-stage KOA in the long term. This may be related to brain structure changes and maladaptive plasticity in KOA patients. Transcranial Magnetic Stimulation (TMS) could enhance the functional connectivity of brain regions and improves maladaptive plasticity. However, the synergistic effect of the combination of the two for treat KOA is still unclear. Therefore, the purpose of this study is to investigate whether the High-Frequency rTMS combined with quadriceps strength training can improve the pain and function in KOA more effectively than quadriceps training alone and explore the mechanism of action.MethodsThis study is an assessor-blind, sham-controlled, randomized controlled trial involving 12 weeks of intervention and 6 months follow-up. 148 participants with KOA will receive usual care management and be randomized into four subgroups equally, including quadriceps strength training, high-frequency rTMS training, sham rTMS and quadriceps strength training, high-frequency rTMS and quadriceps strength training. The rehabilitation interventions will be carried out 5 days per week for a total of 12 weeks. All outcomes will be measured at baseline, 4 weeks, 8 weeks, and 12 weeks during the intervention and 1 month, 3 months and 6 months during the follow-up period. The effectiveness outcomes will be included visual analog scale, isokinetic knee muscle strength, Knee Injury and Osteoarthritis Outcome score and 36-Item Short-Form Health Survey score; The act mechanism outcomes will be included motor evoked potential, grey matter density, white matter, subcortical nuclei volumes, cortical thickness and functional connectivity by MRI. Two-way of variance with repeated measures will be used to test the group and time effect for outcome measures.DiscussionThe study will be the first protocol to examine whether there are synergistic effects following high-frequency rTMS combined with quadriceps strength training for treat KOA and clarify the mechanism of action. High-frequency rTMS can be added into the training program for KOA patients if it is proven effective.Trial registrationChinese Clinical Trial Registry ChiCTR2300067617. Registered on Jan.13,2023.

The Addition of the Gracilis Tendon to a Semitendinosus Tendon Autograft Is Not Associated With Knee Muscle Strength, Subjective Knee Function, or Revision Surgery After Anterior Cruciate Ligament Reconstruction

PurposeTo evaluate and compare isokinetic knee muscle (extension and flexion) strength, single-leg-hop (SLH) test performance, anterior knee laxity, subjective knee function and the 2-year revision surgery risk between patients who underwent anterior cruciate ligament (ACL) reconstruction (ACLR) with a semitendinosus tendon autograft (ST) or a semitendinosus and gracilis tendon autograft (ST+G). MethodsPatients aged 16 years or older who underwent primary ACLR with a hamstring tendon autograft at our institution from January 2005 to December 2020, with no associated ligament injuries, were identified. Isokinetic knee muscle strength and SLH test performance were assessed 6 months postoperatively. Anterior knee laxity (KT-1000 arthrometer, 134-N) was assessed preoperatively and 6 months postoperatively. The Knee injury and Osteoarthritis Outcome Score (KOOS) was collected preoperatively and 1 and 2 years postoperatively. Patients who underwent revision ACLR at any institution in the country within 2 years of primary surgery were identified through the Swedish National Knee Ligament Registry. ResultsA total of 6,974 patients (5,479 ST and 1,495 ST+G) were included. There were no significant differences in extension and flexion strength or SLH test performance between the groups. Preoperatively, there was no significant difference in knee laxity between the ST and ST+G groups. Postoperatively, the ST+G group had a significantly increased mean side-to-side (STS) laxity (2.1 ± 2.3 mm vs 1.7 ± 2.2 mm; P <.001) and showed a trend towards an increased STS laxity according to the IKDC form, with significantly fewer patients with an STS laxity of ≤ 2 mm (58.4% vs 65.8%) and significantly more patients with an STS laxity of between 3 and 5 mm (35.0% vs 29.9%) or > 5 mm (6.6% vs 4.3%) (P < .001). The only significant difference in subjective knee function was for the KOOS Quality of Life score in favor of the ST group preoperatively (37.3 ± 21.4 vs 35.1 ± 19.9; P = .001). No other significant differences between the groups were found preoperatively and 1 and 2 years postoperatively for any of the KOOS subscales. The overall revision ACLR rate within 2 years of primary surgery was 2.0% (138/6,974). The revision ACLR risk for the ST+G group (1.7%; 25/1,495) was not significantly different from that of the ST group (2.1%; 113/5,479) (Hazard Ratio [HR] 0.80; 95%, CI, 0.50-1.24; P = .32). ConclusionThe addition of the gracilis tendon to an ST autograft was not associated with knee muscle strength, SLH test performance, subjective knee function or the risk of revision surgery after ACLR. Level of EvidenceLevel III, retrospective comparative study

Longitudinal Development of Physical Characteristics and Function in Japanese Junior Rugby Union Players.

To longitudinally investigate the development of physical characteristics and function during 3years of high school among Japanese junior rugby players and examine the differences in these parameters between the positions. In 83 junior rugby players (forwards: n = 46, backs: n = 37) from one Japanese high school team who had participated in national high school competitions, anthropometric variables (height, body mass, fat and lean body mass, and body mass index), upper- and lower-body strength (eg,1-repetition-maximum [1RM] bench press, isokinetic knee muscle strength at 60°/s and 180°/s), and sprint and jump performance were measured. Upper- and lower-body strength relative to body mass and lean body mass were also calculated. All anthropometric indices improved with increasing age, and the values were higher in forwards than in backs (all P < .05). The 1-repetition maximum bench press (forwards: 40.8%, backs: 52.5%) and isokinetic knee strength (eg,extension at 60°/s, forwards: 15.4%, backs: 10.0%) improved with age (from 16 to 18y), and they were higher in forwards than in backs (all P < .05). Meanwhile, the 1RM bench press relative to lean body mass did not differ between the positions. Isokinetic knee muscle strength at 60°/s and 180°/s relative to lean body mass and sprint and jump performance did not improve with age. These results indicate that Japanese junior rugby players need to develop larger physiques and continuously increase their lower-body strength to improve sprint and jump performance.

A comparison between hypertonic dextrose prolotherapy and conventional physiotherapy in patients with knee osteoarthritis.

The aim of the present study was to compare the efficacy of hypertonic dextrose prolotherapy (HDP) with conventional physiotherapy (CPT) in improving symptoms in females with knee osteoarthritis (OA). The present study included 60 patients with a diagnosis of knee OA. The patients were randomly assigned to the HDP (n=30) and CPT (n=30) groups. The patients in the HDP group were treated with a dextrose injection into the knee joint (25% dextrose) and around the knee (15% dextrose) in two sessions for 1 month, while those in the CPT group received a hot pack, transcutaneous electrical nerve stimulation and therapeutic ultrasound in five sessions a week for 4 weeks. Prior to commencing the treatment, and at 1 and 3 months post-treatment, all the patients were evaluated using the visual analog scale (VAS), Western Ontario and McMaster Osteoarthritis Index (WOMAC), the goniometric measurement of active knee range of motion (ROM), a 50-m walking test and isokinetic knee muscle strength measurements. There were no statistically significant differences between the two groups as regards the demographic characteristics at pre-treatment (P>0.05). However, at 1 and 3 months post-treatment, the scores of all the outcome parameters were significantly improved in the HDP group compared with the CPT group (P<0.05 for all). In both groups, a significant improvement was observed in the VAS scores, WOMAC total values and ROM following the treatments, with the greatest improvement observed in the HDP group (P<0.001). The isokinetic quadriceps peak torque measurements were increased in both groups following treatment. All the scores exhibited a statistically significant improvement in the HDP group at both 1 and 3 months post-treatment. On the whole, the results of the present study demonstrate that both HDP and CPT are effective treatment modalities to relieve pain, and increase functionality and strength in patients with knee OA. However, greater improvements in pain and functionality can be achieved with prolotherapy.

폼롤러를 이용한 일회성 자가근막이완이 중학교 배드민턴 학생선수의 하지 근기능에 미치는 영향

The purpose of this study was to evaluate compare the acute effects of self-myofascial release(SMR), static stretching(SS) and no stretcing(NS) used as part of warm-up on muscular functions of elite badminton athletes in middle school. The subjects were eight male badminton athletes The subjects were classified into three group; SMR group, SS group and NS. The subjects visited three times at two week intervals. All subjects were tested for body composition, physical fitness factors, wingate test, and isokinetic knee functions. Statistical analysis was performed using One-way ANOVA. As the result of this study, in the vertical jump, the SMR group(p=.005) was significantly higher than the NS group and the SS group. In addition, the SMR group was significantly higher than the SS group for backward flexibility(p=.016). The SMR group(p=.021) was observed a significantly higher dynamic balance than the NS group. In the wingate test, the relative average power was significantly higher in the SMR group (p=.014) than in the SS group. The isokinetic knee muscle strength was significantly higher in the SMR than in the SS in 60°/sec(PT) Right:extension(p=.014) and 60°/sec(%BW) Right:extension(p=.026). The 180°/sec(AP) was significantly higher in the SMR than in the SS and NS in Right:extension(p=.012). The 180°/sec(%BW) was significantly higher in the SMR than in the SS in Left:extension(p=.019) and Right:extension(p=.013). In conclusion, it is thought that SMR treatment before exercise may increase lower body muscle function in badminton players.

Isokinetic knee muscle strength comparison after enhanced recovery after surgery (ERAS) versus conventional setup in total knee arthroplasty (TKA): a single blinded prospective randomized study

PurposeTotal knee arthroplasty (TKA) combined with the concept of enhanced recovery is of continued worldwide interest, as it is reported to improve early functional outcome and treatment quality without increasing complications. The aim of the study was to investigate isokinetic knee muscle strength after cemented TKA in combination with an enhanced recovery after surgery (ERAS) compared to a conventional setup.MethodsIn the single blinded prospective randomized study, 52 patients underwent navigated primary cemented TKA within an ERAS (n = 30) or a conventional setup (n = 22). Preoperatively, five days and four weeks after surgery isokinetic knee muscle strength with BIODEX-type measuring device (peak torque in Nm, work in Joules and power in Watt) and subjective patient-related outcome measures (PROMs) were investigated.ResultsThe ERAS group showed significantly better outcomes in knee flexion at 180°/s (peak torque (Nm) p = 0.047, work (J) p = 0.040 and power (W) p = 0.016) 5 days postoperatively. The isokinetic measuring at knee extension 60°/s and 180°/s demonstrated no significant difference. The PROMs showed that patients were satisfied with the postoperative results in both groups. After 4 weeks, there was no longer a significant difference in isokinetic measuring at knee extension and flexion between the ERAS and conventional group.ConclusionsTKA with the concept of ERAS improves excellent isokinetic outcome and patient satisfaction. The isokinetic muscle strength measurement can help patients and surgeons to modify expectations and improve patient satisfaction.

A comparison of isokinetic muscle strength in patients with chondromalacia patella: a cross-sectional study.

Chondromalacia patella (CMP), which is one of the most common causes of anterior knee pain in young adults, is often accompanied by reflex inhibition of the quadriceps muscle. In this respect, a significant correlation between isokinetic parameters and knee muscle strengths would be expected. We hypothesized that an isokinetic dynamometer, which objectively evaluates muscle strength, may be an important guide in detecting muscle weakness in new-onset CMP and determining early treatment strategies. A total of 113 participants (mean age 30.33 ± 6.96 years, min: 18, max: 44) were recruited and divided into two groups, thus a CMP group (n=48) and a control group (n=65). The symptom duration of the CMP group and the demographic characteristics of all participants were recorded. Knee flexion and extension muscle strengths were measured at angular velocities of 60°/s and 180°/s [Knee extension Peak Torque at 60°/s (PTE60), Knee flexion Peak Torque at 60°/s (PTF60), Knee extension Peak Torque at 180°/s (PTE180), Knee flexion Peak at 180°/s (PTF180) respectively] (five sets) using an isokinetic dynamometer. We also recorded the total work done in flexion and extension (TWDF and TWDE). A modified MRI staging system based on the Outerbridge arthroscopy system was used to stage CMP. Isokinetic dynamometric parameters were compared between CMP patients and healthy volunteers. 59 healthy volunteers (90.8%) were right-side dominant and 6 (9.2%) left-side dominant. 33 CMP patients (68.8%) were right-side dominant, and 15 (31.3%) left-side dominant. 20 (41.7%) CMP patients were classified as Stage 1, 20 (41.7%) as Stage 2, and 8 (16.7%) as Stage 3. All the PTF60, PTE60, PTF180, and PTE180 values were significantly lower in the CMP group than in healthy controls (all p < 0.05). CMP symptom duration ≥ 6 months was associated with significantly lower knee muscle strength than with symptom duration < 6 months (p < 0.05). Also, a statistically negative correlation was found between MRI stages and PTE60 values (p < 0.05). In conclusion, our findings show that the isokinetic dynamometer reveals muscle weakness in CMP patients, and weakness in isokinetic parameters was negatively correlated with symptom duration and MRI stages. Isokinetic knee muscle strength testing, together with other functional tools, enables the assessment of muscle weakness and early rehabilitation planning for patients with CMP.

Isokinetic knee muscle strength asymmetry in university sweep rowers

The prevalence of musculoskeletal injuries in sweep rowing is high. As nearly 50% of power during sweep rowing is contributed by the legs, the presence of muscle imbalances may predispose rowers to overuse injuries. The purpose of the study was to assess knee muscle strength symmetry between dominant and non-dominant limbs of male and female rowers. A descriptive, quantitative research design was used. Twenty-four male and 13 female rowers aged 18–26 years participated. Bilateral isokinetic knee flexion and extension peak torque and hamstrings/quadriceps (H/Q) ratios were assessed at 60°/s and 180°/s using an isokinetic dynamometer. The data was analysed using Mann-Whitney U and Wilcoxon rank tests and significance was set at p≤0.05. In males, the dominant knee extension torque values at 60°/s and 180°/s were significantly larger than that of the non-dominant side (p≤0.05). In females, the non-dominant eccentric H/Q ratio at 60°/s was 15% larger than that of the dominant side (p=0.019). Bilateral differences observed in knee extension torque for males and in H/Q ratio for females highlight the need for isokinetic testing of sweep rowers, to improve performance and prevent injury.

Effect of the frequency of weight-free vibration training on the isokinetic strength of knee muscles in juvenile football players

BACKGROUND: Vibration training can affect strength improvement. However, the role of the vibration frequency, in terms of knee muscle strength, is unclear. OBJECTIVE: To evaluate the effect of vibration training with the same amplitude and different frequencies on the isokinetic muscle strength of the knee in juvenile football players. METHODS: Juvenile football players were divided into four groups: low frequency (n= 13, 25 Hz), medium frequency (n= 14, 40 Hz), high frequency (n= 14, 50 Hz), and control (n= 13). The frequency groups completed 12 weeks of weight-free vibration training (three times/week) with the same amplitude (3 mm) but different frequency. RESULTS: Compared with baseline, the peak extension torque of the knee at 60∘/s and 240∘/s increased by 8.4% and 12.9%, respectively, in the medium-frequency group, and by 8.9% and 15.5%, respectively, in the high-frequency group. The extensor endurance (the ability of joint muscle groups to maintain a force output over time) of the knee in the high-frequency group increased by 4.3%. At 12 weeks, the high-frequency group had greater knee extensor endurance than the low- and medium-frequency groups. CONCLUSION: In juvenile football players, weight-free vibration training at 40 Hz and 50 Hz improves peak torque of the knee extensors at 60∘/s and 240∘/s, while training at 50 Hz improves endurance of the knee extensors.

Functional and molecular adaptations of quadriceps and hamstring muscles to blood flow restricted training in patients with ACL rupture.

Effects of low-load blood flow restricted (LL-BFR) training remain unexplored in patients with ACL rupture. Our hypothesis was that LL-BFR training triggers augmented gains in knee muscle strength and size, which are paralleled with transcriptional responses of hypoxia-regulated genes and myokines. Eighteen volunteers (age 37.5±9years) planned for ACL reconstruction, participated in the study. Twelve were divided between BFR group, performing 9 sessions of LL-BFR exercise, and SHAM-BFR group performing equal training with sham vascular occlusion. Six subjects served as a control for muscle biopsy analysis. Cross-sectional area (CSA) and isokinetic strength of knee muscles were assessed before and after the training. Change in CSAquad was significantly (p<0.01) larger in BFR (4.9%) compared with SHAM-BFR (1.3%). Similarly, change in peak torque of knee extensors was significantly (p<0.05) larger in BFR (14%) compared with SHAM-BFR (-1%). The decrease in fatigue index of knee extensors (6%) was larger (p<0.01) in BFR than in SHAM-BFR (2%). mRNA expression of HIF-1α in the vastus lateralis was reduced (p<0.05) in SHAM-BFR, while VEGF-A mRNA tended to be higher in BFR. The mRNA expression of myostatin and its receptor were reduced (p<0.05) in the semitendinosus after both types of training. Expression of IL-6, its receptors IL-6Rα and gp130, as well as musclin were similar in control and training groups. In conclusion, our results show augmented strength and endurance of knee extensors but less of the flexors. LL-BFR training is especially effective for conditioning of knee extensors in this population.

Flywheel or free weight training for improvement of lower limbs strength?

New training methods are constantly used to improve the ability of skeletal muscles to develop strength. The aim of the present study was to investigate the effect of half-squat training with free weights and flywheel device on isokinetic knee muscle strength for well-trained amateur soccer players. Forty eight players were randomly divided into three groups (n= 16 each): Desmotech Training group (DT), Free Weight Training group (WT) and one Control Group (CON). DT and WT performed an eight-week half-squat training program, with two sessions per week. The DT group performed training with a flywheel device. Isokinetic concentric-eccentric strength assessments of the knee extensors-flexors muscle groups were performed at different angular velocities (60, 180 and 240∘/s). The eight-week training program improved all the isokinetic joint moment indicators examined in the DT and WT groups (p< 0.01). The DT group achieved higher performances at all the isokinetic parameters examined, however, without statistically significant differences to the WT group. Flywheel-based exercise is an effective training method and is suggested to be used to strengthen the lower limbs of soccer players.

Muscle strength particularity of Grand Tour cyclists from knee isokinetic assessment

Summary Objectives To take part in a Grand Tour, the selection of the cyclists is not easy despite a link between isokinetic knee muscle strength and sprinting power. This study aimed to measure knee muscle strength among professional cyclists and to explore the difference in lower limb force between the rouleur/sprinter and the puncher/climber cycling tactic profiles. Materials and methods Thirty nine professional cyclists, who participated in at least one Grand Tour, were assessed at knee level with an isokinetic dynamometer. The relative peak torques normalised to the body mass at the 60, 180 and 240°/s angular speeds and the Limb Symmetry Index, were assessed. Four parameters of the Fatigue testing were studied: total work/kg of extensors and flexors, Fatigue slopes, breakpoint and angle. Results All knee extensors isokinetic parameters, excepted extensor LSI, were different between the 2 groups. The best prediction to identify rouleurs/sprinters was found with 2 parameters: knee extensors strength at 240°/s (Odd-ratios: 1440; P = 0.03) and extensors fatigue slope (ORs: 2.57; P = 0.02). The Receiver Operating Characteristic curves areas were respectively 0.851 and 0.840. Conclusion Isokinetic knee extensors strength and fatigue slope of rouleurs/sprinters are different from those of climbers/punchers. Isokinetic knee extensor's force could represent a new tool to select rouleurs/sprinters for a Grand Tour.

Functional outcome after recurrent patellar dislocation : Comparison of two surgical techniques-Medial patellofemoral ligament reconstruction (MPFL) vs. Elmslie Trillat procedure.

SummaryBackgroundThere is no final consensus regarding the ideal surgical technique for the treatment of patellar dislocation. The aim of this retrospective pilot study was to describe muscle strength, body composition, self-reported physical performance, and pain in male patients after patellar dislocation treatment with two different surgical techniques: medial patellofemoral ligament (MPFL) reconstruction vs. the Elmslie-Trillat procedure.MethodsIsokinetic testing of knee extensor muscles was performed using a Biodex System 3 pro dynamometer at an angular velocity of 60°/s. Body composition was measured with bioelectrical impedance analysis (Nutribox). Self-reported physical performance and pain were assessed by the SF-36 subscales of physical functioning, role physical and bodily pain. The outcome variables of peak torque normalized to participant’s body mass (Nm/kg), lean body mass, phase angle, self-reported physical performance, and pain were compared between the study groups.ResultsOf the 12 included male patients, 6 had been treated with MPFL reconstruction (age: median = 33 years, range = 18–38 years; BMI: median = 26 kg/m2, range = 23–29) and 6 with the Elmslie-Trillat procedure (age: median = 26 years, range = 19–32 years; BMI: median = 23 kg/m2, range = 19–28). No statistically significant differences were found between the groups in any outcome parameter of muscle strength, body composition, self-reported physical performance, or pain.ConclusionsThe results of the present pilot study revealed that MPFL reconstruction shows equal results to the Elmslie-Trillat procedure, with respect to isokinetic knee muscle strength, body composition, self-reported physical performance and pain in male patients suffering from recurrent patellar dislocation.

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

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.

The association between the isokinetic muscle strength and lower extremity injuries in young male football players

BackgroundValidating any screening test to predict and prevent football injuries is in need of identifying related risk factors through prospective designs. In spite of the extensive use of strength testing in football players, there are limited studies investigating the relationship between isokinetic muscle strength and injury risk in young football players. The present study aimed to evaluate the relationship between isokinetic strength and the risk of lower extremity injury among Iranian young football players. Methodology: seventy three U-21 football players participated in this study. Isokinetic strength of hip, knee and ankle muscles were measured using the Isokinetic system pro 4. Injuries and exposure in training and matches were registered prospectively by club medical staff for one season. ResultsSignificant relationships were revealed between the isokinetic strength of hip abductor and adductor muscles, and isokinetic strength ratio of hip abductor/adductor muscles at an angular speed of 30°/sec, the isokinetic strength of hip abductor muscles at 90°/sec, and isokinetic strength of knee flexor and extensor muscles at 60°/sec and knee flexor/extensor strength ratio at angular velocities of 60°/sec with the injury occurrence among football players.Conclusion: lower extremity isokinetic strength indices are associated with injuries in young male football players.

Effects of the FIFA 11+ on ankle evertors latency time and knee muscle strength in amateur futsal players

Background: The FIFA 11+ has shown to increase muscle strength and reduce injury risk. The purpose of this study was to assess the short and long-term effects of the FIFA 11+ on knee strength, and muscle latency after sudden inversion of amateur futsal players. Methods: Seventy-one male futsal players were recruited and randomized to a FIFA 11+ (n = 37, age: 27.0 ± 5.1 years) and a control group (n = 34, age: 26.0 ± 5.1 years). The FIFA 11+ programme was executed twice a week, for 10 weeks, followed-up after 10 weeks where both groups executed regular warm-ups. Concentric and eccentric isokinetic knee muscle strength was tested and latency time of the evertor muscles after sudden inversion of the ankle was executed with a trapdoor mechanism following an EMG protocol of selected leg muscles (peroneus brevis and peroneus longus). Results: No significant difference were observed between groups for short-term changes in isokinetic strength after adjustment for baseline differences. At long-term, significant gains were obtained after adjustment for baseline differences in eccentric strength for both lower limbs as for the H/Q ratios for the dominant limb. No changes between groups were observed in the peroneus brevis and peroneus longus latency time. Conclusions: Performing FIFA 11+ did not have short-term effects on knee strength and muscle latency after sudden inversion in amateur futsal players. However, significant long-term benefits were observed for eccentric strength and H/Q ratios.

Landing Kinematics, Sports Performance, and Isokinetic Strength in Adolescent Male Volleyball Athletes: Influence of Core Training.

Core control and strength are important for reducing the risk of lower-extremity injury. Current evidence on the effect of core training in male adolescent athletes is limited, and other investigations into the effects of core training often emphasized core strength only. To examine whether core training emphasizing both control and strength of the trunk and hip would improve joint kinematics during landing, sports performance, and lower-extremity muscle strength in adolescent male volleyball athletes. Single group pretest and posttest design. University laboratory. Sixteen male participants (age: 13.4 [1]y, height: 167.8 [8.6]cm, mass: 58.6 [13.9]kg, and volleyball experience: 3.8 [1.5]y) from a Division I volleyball team at a junior high school. Kinematics of the trunk and lower-extremity during box landing and spike jump landing tasks, volleyball-related sports performance, and isokinetic strength of hip and knee muscles were assessed before and after a 6-week core training program. After training, the participants demonstrated decreased trunk flexion angle (P = .01, Cohen's d = 0.78) during the box landing task and reduced the maximum knee internal rotation angle (P = .04, Cohen's d = 0.56) during the spike jump landing task. The average isokinetic strength of hip flexors and external rotators, and knee flexors and extensors also significantly increased (P = .001, Cohen's d = 0.98; P = .04, Cohen's d = 0.57; P = .02, Cohen's d = 0.66; P = .003, Cohen's d = 0.87, respectively); however, sports performance did not show significant changes. A more erect landing posture following training suggests that the core training program may be beneficial for improving core stability. The long-term effect of core training for knee injury prevention needs further investigation.

Profiling the isokinetic knee muscle strength in women with different body mass index

Objective: Anterior knee pain is prevalent in obese. In addition to an excess of body mass, a weakness of the thigh muscles and their imbalance are considered risk factors for injury to the knee joint. Therefore, identifying the presence of these risk factors in obese individuals may help to direct knee injury prevention programs. Thus, our aim were to identify whether the thigh muscle strength and the muscle balance ratio are different among women with different body mass index (BMI). Approach: Seventy-six women were recruited. The volunteers were classified according to their BMI. The volunteers were divided into four groups: eutrophic (n = 12; 22.7 ± 1.6 kg m−2), overweight (n = 29; 28.1 ± 1.4 kg m−2), obesity class I (n = 22; 32.6 ± 1.6 kg m−2) and obesity class II (n = 13; 37.1 ± 1.5 kg m−2). The volunteers were submitted for an assessment of their body composition by dual-energy x-ray absorptiometry and an assessment of the muscle performance of the knee flexor and extensor muscles by isokinetic dynamometer. Main results: Women with higher BMI presented more lean body mass (p < 0.05). The peak torque of the knee flexor and extensor muscles did not differ in the four groups (p > 0.05), but the peak torque relative to the total body mass of the flexor and extensor muscles was lower in the women with overweight and obesity than in the eutrophic women (p < 0.05). There was no significant difference between the groups regarding the muscle balance ratios (p > 0.05). Significance: The obese women presented less relative muscle strength, which may be related to a greater risk of injury to the knee joint.