Extensor Peak Torque Research Articles

Assessment of isokinetic trunk muscle parameters, postural control and quality of life in sedentary and active older adults

ObjectiveThe study intended to evaluate the differences between active and sedentary postural control and isokinetic trunk strength. The secondary aim was to evaluate the participants' total physical activity (PA) score regarding the specific quality of life domains assessed. MethodsAn analytical cross-sectional study involving 64 participants of both sexes aged ≥ 60 years (60 to 86 years) was conducted. Habitual PA was assessed using the Baecke Modified Questionnaire for older adults, and participants were classified as active or sedentary. Quality of life was assessed using the SF-36 questionnaire, postural control was evaluated using a bipedal force plate, and trunk muscle strength was measured using an isokinetic dynamometer. The independent t-test, Spearman correlation, and Generalized Linear Model were employed, with a significance level of 5%. ResultsNo significant differences were observed in postural control between active and sedentary participants. However, significant differences were observed in the peak touch and mean power of trunk extensors and flexors at speeds of 60 and 180◦/s (p<0.005), except for the ratio between flexor and extensor muscle peak torque assessed at both speeds. Quality of life showed significant correlations with PA level regarding the domains of functional capacity, vitality, and health conditions. The logistic model revealed an association with the domains of functional capacity and pain in relation to PA. ConclusionOur results underscore the importance of regular PA practice for the older adult population, indicating the enhancement of health-related quality of life and the strength of trunk extensors and flexors.

Running Plus Strength Training Positively Affects Muscle Strength and Quality in Both Younger (Below 50 Years Old) and Older (Above 50 Years Old) Women.

Sarcopenia is a muscular disease characterized by loss of muscular strength and function, affecting mainly women, and associated with increased mortality risk. The aim of this study was to compare active women with inactive women of different age groups regarding muscle mass, strength, and muscle quality. This study included 147 women (85 runners and 62 inactive), divided into <50 and ≥50 years old. Participants were evaluated for knee flexor and extensor peak torque (PT), body composition, and training habits. For knee extensor muscles, there was an age group effect (F(2.146) = 40.5; p < 0.001) on absolute PT (Nm); an age group effect (F(2.146) = 44.1; p < 0.001) and a physical activity group effect (F(2.146) = 113.0; p < 0.001) on PT adjusted by body mass (Nm/kg); and an age group effect (F(2.146) = 36.9; p < 0.001) and a physical activity group effect (F(2.146) = 6.1; p = 0.014) on PT adjusted by lean mass (Nm/kgLM). There was no interaction effect. In both age groups, active women had greater strength and higher muscle quality than inactive women, but the difference in strength, muscle mass, and muscle quality between younger and older women were the same among runners and inactive women.

Age-related effects on absolute and relative isokinetic knee extensor strength in community-dwelling older men and women at a French geriatric day hospital.

Isokinetic knee extensor strength is poorly evaluated in geriatric day hospitals (GDHs), despite its potential functional significance compared to grip strength. This study aimed to investigate age-related effects on absolute and relative isokinetic knee extensor peak torque (KEPT) data in community-dwelling older GDH patients. A total of 472 French GDH patients (179 men and 293 women, aged 75-94 years) participated in this study. Absolute and relative KEPT were measured at six distinct angular velocities between 0.52 and 3.14 rad/s. In addition, comfortable gait speed and grip strength were assessed. Participants were stratified by sex and age using 5-year intervals. One-way ANOVAs were used to examine age-related effects on KEPT values. Multiple linear regression models were employed to investigate the associations between gait speed and both mean KEPT values and grip strength, with separate models conducted on absolute and relative values. The recruited GDH patients presented lower absolute and relative KEPT values in comparison with established reference values for healthy community-dwelling older individuals, with men being consistently stronger than women. Notably, there was a significant decline in both absolute and relative KEPT values beyond the age of 85 for both sexes. Importantly, the multiple linear regression analyses conducted revealed a significant positive relationship between gait speed and mean KEPT values, surpassing the association with grip strength. These findings underscore the clinical importance of assessing isokinetic knee extensor strength in community-dwelling older GDH patients, particularly for tailoring personalized physical activity interventions.

Impact of Leg Strength on the Force Produced During a Cross-Punch in Highly Trained Amateur Boxers.

Satkunskiene, D, Bruzas, V, Mantas, M, Snieckus, A, and Kamandulis, S. Impact of leg strength on the force produced during a cross-punch in highly trained amateur boxers leg strength impact on cross-punch force. J Strength Cond Res XX(X): 000-000, 2024-The purpose of this study was to determine the impact of leg strength on force generation during the execution of a cross-punch by highly trained amateur boxers. This study involved 12 male, amateur boxers with a body mass range of 64.5-112.2 kg and a mean of 89.2 ± 17.0 kg. This study used an isokinetic dynamometer to measure the peak torque of the knee extensor and flexor muscles at 60°/s. The force plate was used to collect three-dimensional ground reaction forces (GRF), moments (GRM), and the center of pressure (COP) during a maximal cross-punch. The Kiktest-100 system was used to determine the force of the punch, while the Hykso punch tracker accelerometer measured the maximum fist velocity. This study revealed a positive correlation between knee extensor strength and GRFz, GRFy, and COPy during punch performance. In addition, the GRMz gradient and GRMz impulse during the execution phase have a significant positive effect on cross-punch force. In conclusion, the force of a straight punch in highly trained, amateur boxers is related to a greater angular velocity about the vertical axis during body rotation.

Changes in isokinetic trunk muscle strength and endurance after two different restoration programs in people with chronic low back pain: A longitudinal retrospective study

BackgroundMultidisciplinary functional restoration programs (FRPs) aim to improve pain and function in people with chronic low back pain (CLBP). The intensity and content of FRPs varies; the benefits of one program over another are unclear. ObjectiveTo assess changes in trunk muscle strength and endurance after an intensive (IFRP) (for people on sick leave for >6 months with high levels of fear-avoidance beliefs about physical activity and work) or semi-intensive (SIFRP) (for people working) FRP in people with CLBP. MethodsLongitudinal retrospective study from March 2016 to December 2019. Setting: rehabilitation department of a tertiary care center. Trunk flexor and extensor muscle strength (60°.s−1) and endurance (120°.s−1) were measured with the Humac NORM isokinetic dynamometer at pre and post FRP. Change in isokinetic variables (peak torque, total work and flexor/extensor ratio) after each program was assessed with a paired t-test (p < 0.05). Pearson's rho and multiple linear regression assessed associations between changes in isokinetic and clinical variables and demographic characteristics. Results125 individuals, 63.2 % female, age 43.5 (10.3) years, were included. Mean low back pain intensity was 49.8 (24.9) and 37.2 (25.8)/100 and mean activity limitation (QBPDS) was 38.8 (16.4) and 32.0 (14.6)/100 in the IFRP and SFRP groups, respectively. Trunk extensor peak torque, flexor total work, extensor total work and flexor/extensor peak ratio improved significantly in both FRPs, p < 0.001. The flexor/extensor total work ratio improved in the IFRP group only, p = 0.003. Trunk extensor endurance increased more in the IFRP than the SIFRP group, the absolute pre-post differences for extensor total work [95%CI] N.m were 611.7 [495.2; 728.3] in the IFRP group and 380.0 [300.8; 459.3] in the SIFRP group. No variables were correlated and none predicted improvement in extensor total work in either group. ConclusionThis study highlights the short-term independence of clinical and trunk muscle strength and endurance changes.

Evaluation de la force musculaire chez le lombalgique chronique: Comparaison entre reeducation isocinetique et reeducation classique

Chronic low back pain is a public health problem in view of its functional repercussions and the functional rehabilitation is an integral part of its management. To compare the evolution of muscle strentgh of spinal extensors and flexors in chronic low back pain patients after an isokinetic rehabilitation protocol and a conventional rehabilitation one. This was a prospective and comparative study carried out in the Physical Medicine Department of the Tunis Military Hospital over a period of 7 months. Fifty patients were included, randomly divided into two groups of 25. The first group (G1) benefited from an isokinetic rehabilitation protocol and the second one (G2) from a classic active physiotherapy. We performed a clinical (Sorensen test and Shirado test) and isokinetic evaluation of the trunk muscles before and after rehabilitation. The mean age of the general population was 42±8.6 years old. Clinical evaluation showed a deficit in the extensor and flexor muscles of the spine, more important in the extensors in both groups. After rehabilitation, there was a significant improvement in clinical tests of muscular endurance in G1 and G2. Isokinetic assessment showed a greater muscle deficit in the extensors in both groups. After isokinetic rehabilitation, peak torque for flexors and extensors increased by 21% and 23% respectively, power was 34% and 37% higher, and total work increased by 26% and 47%. On the other hand, the (F/E) ratios were unchanged for all three speeds. In Group 2, peak torque values for flexors and extensors increased by 22 and 15% respectively, power was higher by 31 and 23% and total work was also up by 29 and 17%, while F/E ratios were also unchanged. Group 1 showed the greatest improvement in extensor strength at 60°/s, and in power at 90°/s for the various muscles. In our study, we concluded that endurance and muscular strength improved the most after isokinetic rehabilitation.

Effect of Step Load Based on Time under Tension in Hypoxia on the ACL Pre-Operative Rehabilitation and Hormone Levels: A Case Study.

The aim of the study was to determine the effect of step load in hypoxia on the effectiveness of preoperative rehabilitation (PR) and hormone levels based on a case study. Introduction: We assessed the impact of variables such as rate of movement and time under tension (TUT) in normobaric hypoxia on the levels of growth hormone (GH), insulin-like growth factor 1 (IGF-1), and erythropoietin (EPO). Additionally, the impact of step load on the hypertrophy and strength of knee extensors and flexors was assessed. Methods: The work uses a case study, the research subject of which was a 23-year-old female professional handball player. The tests included an isokinetic assessment of the peak torque of knee extensors and flexors as well as body composition analysis. Results: The results showed a more than (10.81-fold) increase in GH after the microcycle with time under tension (TUT). The deficit between the lower limbs was also reduced. Conclusions: Using a hypoxic environment based on an appropriate altitude, combined with changes such as a short rest break between sets and a controlled tempo of movement with an eccentric phase, TUT may offer an alternative to the PR process, especially among athletes who care about fast RTS.

The effects of resistance training on denervated myofibers, senescent cells, and associated protein markers in middle-aged adults.

Denervated myofibers and senescent cells are hallmarks of skeletal muscle aging. However, sparse research has examined how resistance training affects these outcomes. We investigated the effects of unilateral leg extensor resistance training (2 days/week for 8 weeks) on denervated myofibers, senescent cells, and associated protein markers in apparently healthy middle-aged participants (MA, 55 ± 8 years old, 17 females, 9 males). We obtained dual-leg vastus lateralis (VL) muscle cross-sectional area (mCSA), VL biopsies, and strength assessments before and after training. Fiber cross-sectional area (fCSA), satellite cells (Pax7+), denervated myofibers (NCAM+), senescent cells (p16+ or p21+), proteins associated with denervation and senescence, and senescence-associated secretory phenotype (SASP) proteins were analyzed from biopsy specimens. Leg extensor peak torque increased after training (p < .001), while VL mCSA trended upward (interaction p = .082). No significant changes were observed for Type I/II fCSAs, NCAM+ myofibers, or senescent (p16+ or p21+) cells, albeit satellite cells increased after training (p = .037). While >90% satellite cells were not p16+ or p21+, most p16+ and p21+ cells were Pax7+ (>90% on average). Training altered 13 out of 46 proteins related to muscle-nerve communication (all upregulated, p < .05) and 10 out of 19 proteins related to cellular senescence (9 upregulated, p < .05). Only 1 out of 17 SASP protein increased with training (IGFBP-3, p = .031). In conclusion, resistance training upregulates proteins associated with muscle-nerve communication in MA participants but does not alter NCAM+ myofibers. Moreover, while training increased senescence-related proteins, this coincided with an increase in satellite cells but not alterations in senescent cell content or SASP proteins. These latter findings suggest shorter term resistance training is an unlikely inducer of cellular senescence in apparently healthy middle-aged participants. However, similar study designs are needed in older and diseased populations before definitive conclusions can be drawn.

Influence of strength and balance ability on functional performance in the involved and uninvolved sides after anterior cruciate ligament reconstruction.

The restoration and management of the uninvolved side have been emphasized to prevent a second anterior cruciate ligament (ACL) injury and to ensure that athletes return to sports after ACL reconstruction. To determine the factors influencing the single leg hop test (SLHT) and single leg vertical jump test (SLVJT) at 1 year postoperatively after ACL reconstruction in both the involved and uninvolved sides. Ninety-four patients who underwent ACL reconstruction were assessed at 1 year postoperatively. Multiple regression models included eight independent variables with two dependent variables (SLHT and SLVJT.), each on the involved and uninvolved side. On the involved side, the Y balance test (YBT), extensor peak torque per body weight (PT/BW), Biodex balance system anteroposterior index (BBS-API), and sex accounted for 53.9% of the variance in SLHT (P= 0.002), and extensor PT/BW and YBT accounted for 26.3% of the variance in SLVJT (P= 0.027). On the uninvolved side, YBT, sex, age, BBS-API, and flexor PT/BW accounted for 47.0% of the variance in SLHT (P= 0.046), and flexor PT/BW, YBT, and age accounted for 44.9% of the variance in SLVJT (P= 0.002). Knee extensor strength on the involved side and flexor strength on the uninvolved side influence the two functional performance tests. The YBT was an important factor in the two functional performance tests in both sides. Anteroposterior stability was the only factor that influenced the SLHT bilaterally.

Concurrent training associated with moderate walnut consumption improved isokinetic strength, subjective sleep quality, cognitive performance and postural balance in elderly active men: a randomized controlled trial

AimsTo investigate the effects of concurrent training (resistance and endurance) associated with moderate walnut consumption on isokinetic strength, subjective sleep quality, cognitive performance and postural balance in physically active elderly men.MethodsTwenty healthy elderly men were divided into two matched groups, in a randomized controlled experiment. They have participated in three training sessions per week: concurrent (strength and endurance) training + ad libitum diet with walnuts (15 g/day for 6 weeks, CTW: n = 10) and concurrent training + ad libitum diet (CT: n = 10). Isokinetic strength, Spiegel questionnaire, Montreal cognitive assessment and postural balance parameters were assessed 48 h pre- and post-intervention.ResultsAbsolute peak torque of knee extensors and knee flexors significantly increased compared to pre-training in CTW (15.2% ± 6.7; 13.2% ± 2.3, p < 0.05, respectively) and CT (10.6% ± 6.8; 7.4% ± 2.9, p < 0.05, respectively). Subjective sleep quality increased compared to pre-training for CTW and CT (24% ± 14.4; 10.5% ± 9.4, p < 0.05, respectively) with a significantly greater increase in CTW (p < 0.05). Cognitive performance measured by Montreal cognitive assessment (MoCA) increased only in CTW compared to baseline (7.7% ± 2.5, p < 0.05). Postural balance parameters with dual task decreased only in CTW compared to baseline.ConclusionsThe present study clearly revealed that concurrent training alone or associated with daily walnut (15 g) consumption for 6 weeks significantly increased knee isokinetic strength, support leg standing parameters and sleep quality. Meanwhile, cognitive performance evaluated by MoCA test and postural balance with dual task were improved for CTW group only.

A Comparison of a Step Load Unilateral and Bilateral Resistance Training Program on the Strength and Power of the Lower Limbs in Soccer Players

The purpose of the investigation was to determine the influence of a four-week unilateral (UNI) and bilateral (BIL) resistance training program on peak torque and peak power of the lower limbs in soccer players. Background: We evaluated the effects of a 3:1 step load training program using UNI and BIL forms of exercises on the level of peak torque and peak power of the knee joint extensors and flexors. Methods: The study included 16 division I soccer players having the highest number of matches played in the first round of the season. The motor tests included isokinetic evaluation of peak torque and peak power of the extensors and flexors of the knee joint. Results: The results showed that both types of training sessions were equally effective. Only in terms of power during knee flexion, unilateral training contributed to improvement, whereas bilateral training did not. Conclusions: The use of periodization using a step load progression based on an extended eccentric phase of the movement during the preseason period in combination with UNI training may increase peak torque and peak power of knee flexors and extensors in soccer players.

A single all-out bout of 30-s sprint-cycle performed on 5 consecutive days per week over 6weeks does not enhance cardiovascular fitness, maximal strength, and clinical health markers in physically active young adults.

This study examined the effects of a single all-out bout of 30-s sprint-cycle performed daily for 5 consecutive days per week for 6weeks, on aerobic fitness, muscle strength and metabolic-health markers in physically active young males and females. Healthy, physically active 20-28year olds, were randomly assigned to either experimental (EXP, N = 11) or non-training control (CON, N = 8) group. With supervision, the EXP group performed one bout of 30-s sprint-cycle daily, Mondays to Fridays over 6weeks, while CON group continued with their usual lifestyle. The followings were measured at pre- and post-intervention: maximal aerobic power, peak torque of knee extensors and flexors at velocities 30°s-1 and 300°s-1, resting heart rate, resting blood pressure, body fat percentage, fasting lipid profile, fasting blood glucose, and fasting insulin levels. There were no significant improvements in the EXP group for all the measured variables (all P > 0.05); except for significant interaction effects in peak torque of knee extensors at 30°s-1 (P = 0.044) and low-density lipoprotein-cholesterol (P = 0.046). Post hoc test indicate that CON group showed decline in their low-density lipo-proteins levels (P = 0.024). Six weeks of one all-out bout of 30-s sprint-cycle per day, for 5 consecutive days per week, was ineffective in improving cardiovascular fitness, maximal strength, and most health markers in physically active young adults. The present results when combined with the previous literature suggest that there is a possibility of a minimum threshold for a number of sprint-cycle bouts needed to be performed before any form of cardio-metabolic-health benefit is accrued.

Improving muscle capacity utilization with a 12-week strengthening program for females with symptomatic knee osteoarthritis

BackgroundStrengthening exercise improves symptoms in knee osteoarthritis (OA), but it remains unclear if biomechanical mechanisms contribute to this improvement. Muscle capacity utilization, which reflects the proportion of maximum capacity required to complete tasks, may provide insight into how strengthening exercise improves clinical outcomes in painful knee OA. PurposeThe purpose of this secondary analysis was to determine if a 12-week strengthening intervention reduced muscle capacity utilization during walking, squat and lunge tasks in females with painful knee OA. MethodsData from 28 females (age 59.6 ± 6.2 years old; body mass index 29.1 ± 4.7 kg/m2) with clinical knee OA were included. Participants completed a strengthening intervention 3 times per week for 12 weeks. Knee extensor isometric torque was measured on a commercial dynamometer; peak values from three exertions were averaged. Peak KFM was extracted and averaged from five walking trials. Mean KFM was extracted and averaged from three trials for each of static lunges and squats. Muscle capacity utilization was the ratio of mean peak KFM to peak extensor torque for walking; and mean KFM to peak extensor torque for squats and lunges. Paired t-tests determined differences between peak extensor torque, peak KFM and muscle capacity utilization from pre to post intervention (p < 0.05). Results & significancePeak extensor torque increased at follow up (p = 0.02). Peak KFM during walking decreased (p = 0.005). Muscle capacity utilization during walking (p = 0.008) and squat (p = 0.002) decreased. Mean KFM and muscle capacity utilization during lunge remained unchanged from pre to post intervention. The reduction in muscle capacity utilization at follow up indicates the strengthening intervention produced a decrease in proportion of the maximal capacity a participant used to complete walking and squat tasks. Strengthening both increases maximal muscle capacity and decreases the net moment required during daily tasks in knee OA.

Effects of blood flow restriction training on muscle fitness and cardiovascular risk of obese college students.

Purpose: The aim of this study was to investigate the effect of blood flow restriction (BFR) combined with low-intensity resistance training (RT) on cardiovascular risk factors in obese individuals. Methods: Twenty-six male obese college students were recruited and randomly assigned to a control group (CON, n = 8), a low-intensity RT group (RT, n = 9), and a combined BFR training and low-intensity RT group (BFRT, n = 9). Results: The subjects in BFRT group showed significant reductions in body fat percentage and waist-to-hip ratio and a significant increase in lean mass and muscle mass; the peak torque, peak power, and endurance ratio of knee extensors and elbow flexors were significantly upregulated; the root mean square (RMS) for the medial femoral muscle, lateral femoral muscle and biceps significantly increased; the diastolic blood pressure (DBP) showed a significant decrease. The BFRT group also showed significant up-regulations in RMS of the difference between the adjacent R-R intervals (RMSSD), high-frequency power (HF) of parasympathetic modulatory capacity, the standard deviation of R-R intervals (SDNN) of overall heart rate variability (HRV) changes and low-frequency power (LF) of predominantly sympathetic activity. In addition, glycated hemoglobin (HbA1C), insulin resistance index (HOMA-IR) and fasting blood glucose (FBG) were all significantly downregulated in BFRT group. In parallel, low-density lipoprotein (LDL-C) significantly reduced while high-density lipoprotein (HDL-C) significantly increased in BFRT group. Conclusion: BFR combined with low-intensity RT training effectively improved body composition index, increased muscle mass, improved neuromuscular activation, enhanced muscle strength and endurance, which in turn improved abnormal glucolipid metabolism and enhanced cardiac autonomic regulation.

CORRELAÇÃO ENTRE TESTES FUNCIONAIS E AVALIAÇÃO ISOCINÉTICA DO JOELHO EM ATLETAS CORREDORES DE RUA

ABSTRACT Introduction: The assessment of biomechanical changes related to the lower limbs is necessary in clinical practice to measure the potential risks of injury and the influences on existing dysfunction. Biomechanical changes related to previous ankle injuries are known to influence the performance of the entire lower limb. Objective: The aim of this study was to correlate muscle strength tests, performance tests and ankle stability with the Single Hop Test (SHT). Methods: 82 amateur runners were evaluated with isokinetic tests of quadriceps and hamstring muscle strength, as well as Y Balance Test (YBT), Weight-bearing Lung Test (WBLT), and the SHT. Results: The results showed there was a significant correlation between the SHT and the YBT in subjects with hamstring/quadriceps ratio (I/Q ratio) &lt;0.55, and the length of the unilateral SHT with the peak torque of ipsilateral knee extensors. Conclusion: The study was successful in correlating the functional tests in question with the results obtained in isokinetic dynamometry. Level of Evidence V; Cross-Sectional Study.

Position- and Sex-Related Differences in Sagittal and Frontal Plane Concentric Isokinetic Hip Muscle Peak Torques and Agonist-Antagonist Ratios.

Hip muscle weakness is associated with many musculoskeletal conditions and athletic injuries. Isokinetic testing is often performed to measure a patient's strength or to assess treatment response. Patient sex and positioning during isokinetic strength testing may influence peak torque production and the agonist-antagonist peak torque ratios. However, different test positions are used clinically and in research to measure hip muscle strength. It is unknown how patient test position or sex impacts test results. The purpose of this study was to determine whether concentric isokinetic peak torques of sagittal and frontal plane hip muscles differ when tested in recumbent versus standing positions and if results were impacted by patient sex. Cross-sectional observational. Forty healthy adults (20 male, 20 female) participated. Concentric isokinetic hip torques of the hip flexors, extensors, abductors, and adductors were measured with participants in two positions (recumbent versus standing; 60°/second angular velocity). Peak torque values were normalized by body mass and height. Data were analyzed with mixed-model ANOVAs (sex x position). Effect sizes were examined using partial eta squared. No significant interactions or main effects for sex were found. Significant main effects for position were found for hip extensor and abductor peak torques and for hip flexor-extensor ratio. Hip extensor peak torque was greater when tested supine versus standing with a large effect size (p=.02, effect size =.14). Hip abductor peak torque was greater when tested sidelying versus standing with a medium effect size (p=.03, effect size =.12). Hip flexor-extensor agonist-antagonist ratio was greater when tested standing versus supine with a large effect size (p<.001, effect size =.27). Hip extensor and abductor concentric isokinetic peak torques were greater when tested in recumbent versus standing positions. In contrast, hip flexor-extensor ratio was greater when tested in standing versus supine. 3.

A comparison in knee flexor and extensor strength following ACL reconstruction in international, male soccer players receiving patellar tendon or hamstrings grafts.

The aim of this study was to compare knee extensor and flexor strength recovery following anterior cruciate ligament (ACL) reconstruction between bone-patellar tendon-bone (BPTB) and hamstring tendon (HT) grafts in international male soccer players undergoing comparable 6-month rehabilitation programmes. Seventeen players underwent ACL reconstruction with either an autogenous BPTB graft or HT graft. Knee extensor and flexor peak torques were measured at 3 months and 6 months in the injured and contralateral legs following surgery using isokinetic dynamometry. The moderate-large asymmetries in knee extensor peak torque between legs at 3 months across graft types (BPTB: p = 0.002, g = -0.94; HT: p = 0.02, g = -0.55) were reduced to trivial asymmetries at 6 months (BPTB: p = 0.30, g = -0.19; HT: p = 0.40, g = -0.16), with a non-significant difference in limb symmetry index (LSI) between grafts at 6 months (p = 0.62, g = -0.24). Similarly, moderate-large asymmetries in knee flexor peak torque between legs at 3 months across graft types (BPTB: p = 0.13, g = -0.50; HT: p = 0.01, g = -0.97) were reduced to trivial-small asymmetries at 6 months (BPTB: p = 0.25, g = 0.18; HT: p = 0.01, g = -0.47); however, a superior LSI was evident with BPTB compared to HT grafts at 6 months (p = 0.007, g = 1.43, large). Strength and conditioning professionals working with soccer players who are rehabilitating from ACL reconstruction after receiving a HT graft should give adequate attention to delivering suitable hamstring exercises that ensure optimal strength restoration.

Lumbar extension peak-torque, muscle endurance and motor imagery in junior-elite basketballers with and without a history of low back pain: a pilot study.

Low back pain (LBP) is common in elite athletes. Several peripheral and central factors have been identified to be altered in non-athletic LBP populations, however whether these alterations also exist in elite athletes with LBP is unknown. The aim of this study was to determine whether elite basketballers with a history of persistent LBP perform worse than those without LBP at a lumbar muscle endurance task, a lumbar extension peak-torque task, and a lumbar motor imagery task. An observational pilot study. Twenty junior elite-level male basketballers with (n=11) and without (n=9) a history of persistent LBP were recruited. Athletes completed a lumbar extensor muscle endurance (Biering-Sorensen) task, two lumbar extensor peak-torque (modified Biering-Sorensen) tasks and two motor imagery (left/right lumbar and hand judgement) tasks across two sessions (48 hours apart). Performance in these tasks were compared between the groups with and without a history of LBP. Young athletes with a history of LBP had reduced lumbar extensor muscle endurance (p<0.001), reduced lumbar extension peak-torque (p<0.001), and were less accurate at the left/right lumbar judgement task (p=0.02) but no less accurate at a left/right hand judgement task (p=0.59), than athletes without a history of LBP. Response times for both left/right judgement tasks did not differ between groups (lumbar p=0.24; hand p=0.58). Junior elite male basketballers with a history of LBP demonstrate reduced lumbar extensor muscle endurance and lumbar extension peak-torque and are less accurate at a left/right lumbar rotation judgement task, than those without LBP.

Correlation between hip muscle strength and the lower quarter Y-balance test in athletes following anterior cruciate ligament reconstruction

IntroductionThe lower quarter Y-balance test (YBT-LQ), which measures dynamic postural control, has been reported to be predictive of lower limb injuries in athletes. It requires subjects to control their body while maintaining a single-leg stance, which necessitates sufficient strength of the hip muscles to maintain stability. The purpose of the study was to investigate the correlation between the performance of the YBT-LQ and the hip abductor or extensor muscle strength in athletes following anterior cruciate ligament reconstruction surgery (ACLR). MethodsFifteen athletes with post-ACLR participated in this cross-sectional study. The participants completed the YBT-LQ, followed by isokinetic measurement of the hip abductor and extensor muscles of both the legs. The peak and average torque of the hip abductor and extensor muscles were tallied with the composite score of the YBT-LQ for each limb. ResultsNo correlation was found between the strength of the hip muscles and the YBT-LQ composite score in both injured and non-injured limbs at all velocities except for the eccentric hip abductor and concentric hip extensor torques. The eccentric hip abductor average torque is strongly associated with the YBT-LQ (r = 0.663, p = 0.010) at a speed of 180°/s. The concentric hip extensor peak torque was weakly correlated with balance (r = 0.540, p = 0.046) at a speed of 180°/s. ConclusionOur study demonstrated a positive correlation between the YBT-LQ and eccentric hip abduction and concentric hip extension at higher velocities. This shows the importance of implementing velocity-oriented rehabilitation in an athletic population following ACLR.

The association between knee muscle performance and clinical outcomes of knee function 1–4 years after a sport-related knee joint injury

ObjectiveEstimate the association between index leg knee muscle strength and rate of torque development (RTD), and self-reported and performance-based (i.e., hop) knee function in persons 1–4 years after a sport-related knee joint injury. MethodsData were collected at baseline of a clinical trial. Assessments included the Knee injury and Osteoarthritis Outcome Score Sport & Recreation subscale (KOOSsport), 6-m timed hop (TH), and peak concentric isokinetic knee extensor and flexor torque and isometric RTD. Associations between peak torque and RTD with KOOSsport and TH were assessed using multivariable regression with nonlinear transformations. Results53 participants (64.2% female) were included. Knee extensor peak torque was nonlinearly related to TH time, with a strong inverse relationship at lower torque values that changed as torque increased. Results were inconsistent for flexor peak torque, extensor RTD and flexor RTD, with inconsistencies in relationship shape and estimates of association between primary and sensitivity analyses. There was no association between strength/RTD and KOOSsport. ConclusionThere was a nonlinear relationship between knee extensor strength and hop function, with lower strength being associated with a stronger relationship. As strength values increased, the relationship attenuated. Knee extensor and flexor strength, or RTD, were not associated with self-reported function.