Extensor Ratio Research Articles

Isokinetic thigh muscles strength in semi-professional athletics: A one season prospective cohort study

IntroductionContinuous evaluations of athletes, including strength testing, can help control performance improvement or facilitate the restoration of normality after an injury. The aim of the present study was to prospectively determine the peak torque (PT), angle at which PT is achieved, and functional ratios of flexors and extensors thigh muscles during one season. Material and methodsThirty semi-professional male athletes competing in long jumping (n = 10), javelin throwing (n = 10), and sprinting (n = 10) participated. PT was evaluated in relation to limb length; the angle at which PT was achieved was obtained from the force-curve displayed in the isokinetic dynamometer; functional ratios were calculated by dividing concentric hamstring strength by eccentric quadriceps strength (flexor ratio) or vice-versa for the extensor ratio. Assessment was performed at 60º/s and 300º/s. ResultsSignificant variations were seen for both extensor and flexor PTs at different stages of the season, with moderate to large effect sizes observed (effect size (d) = 0.49–0.93). Functional ratios and the angle at which peak torque was achieved remained stable throughout the season. ConclusionsThigh muscle strength is unstable throughout a track and field season, coaches or medical staff should consider these findings when programming training sessions or rehabilitating an athlete.

Trunk, Mass Grasp, Knee, and Hip Muscle Performance in CrossFit Participants: Reference Values According to Participants' Sex and Limb Dominance.

CrossFit is characterized by a diverse range of exercises recruiting different muscles and requiring different muscle functions. A characterization of muscular performance parameters in this population is needed. To determine reference values for various aspects of muscular performance of muscles of the trunk, thigh, hip, and mass grasp in CrossFit participants. Also, this investigation aimed to compare the strength measures between male and female CrossFit participants, as well as between dominant and non-dominant limbs. Descriptive, Cross-sectional. Laboratory. Isometric strength of trunk extensors (TE) and mass grasp was measured with handheld and Jamar dynamometer respectively. An isokinetic dynamometer was used to assess the muscle performance of the knee flexors (KF) and extensors (KE) (at 60º/s and 300º/s), and hip flexors (HF), extensors (HE), and abductors (HA) (60º/s and 240º/s ). Reference values for torque, work, power, fatigue, flexor:extensor ratio for the knee (hamstring:quadriceps - H:Q) and hip (HF:HE) joints were calculated. The torque and work values were normalized by the body mass. Mixed multivariate and univariate analyses of variance and independent t-tests were used for statistical analyses to compare between sexes and limbs. Participants included 111 individuals (58 males and 53 females) with at least one year of experience in CrossFit. Normative data are provided for the outcome variables. Males had greater values of muscular performance parameters than females in most variables (p<0.05). Also, the dominant limb had greater mass grasp strength (p<0.002), greater KE power at 60º/s (p=0.015), lower H:Q ratio at 60º/s (p=0.021) and 300º/s (p=0.008), and lower KE fatigue (p=0.002). This study provides reference values for the trunk extensors, mass grasp, knee, and hip muscle performance in male and female CrossFit practitioners. Their muscle performance profile was characterized by few inter-limb asymmetries, and males demonstrated greater muscular performance outcomes than females, even after normalization by body mass. These reference values can be used for comparisons in research and clinical settings. 3b.

Characteristics and usefulness of trunk muscle endurance tests on the Roman chair in healthy adults.

Adequate trunk muscle endurance is considered to be an important indicator of good low back stability; therefore, its assessment is needed when determining an individual's risk for back pain. Optimal tests to assess each trunk muscle group separately are difficult to find. The objective of this study was to verify if two groups of trunk muscle endurance tests (standard and alternative) show comparable results in terms of muscle endurance ratios, holding times and rated perceived effort to perform each test. The study was designed as a quasi-experimental repeated-measures design. There was a single group of participants who took part in two different trunk muscle endurance testing. Sixty-eight healthy adult volunteers, aged 20-45 years (31.9 ± 7.2 years), without recent musculoskeletal injury or disorder participated in the study. All participants finished the study. Trunk muscle endurance tests as tested on the Roman chair (B tests) were compared with standard tests as suggested by McGill (A tests). Each group of tests consisted of an endurance test for trunk extensors, trunk flexors, and lateral trunk muscles for left and right side. The order of tests' performances was randomly assigned to each participant, whereby a participant did perform A and B tests in the same order. In each test of A and B the holding time was recorded and a perceived effort in each test performance was also assessed by participants. Post testing performance the four ratios of trunk muscles endurance comparison were calculated for each group of tests to determine if there is a good or poor ratio between muscles. Results of each participant were compared for trunk muscle endurance ratio calculations, holding times and rated perceived effort for A and B tests. Results showed comparable trunk muscle endurance ratios in the three ratios observed, except for the flexors:extensors ratio (AFL:EX: 1.2 (IQR: 0.7-1.6) vs. BFL:EX: 0.6 (IQR: 0.3-0.8); p < 0.001). As compared to A tests, holding times were significantly longer in B tests for the extensors (AEX: 125.5 s (IQR: 104.8-182.8 s) vs. BEX: 284.0 s (IQR: 213.0-342.3 s); p < 0.001) and lateral trunk muscles (AL-LM: 61.0 s (IQR: 48.3-80.8 s) vs. BL-LM: 131.5 s (IQR: 95.5-158.5 s); AR-LM: 63.5 s (IQR: 45.8-77.3 s) vs. BR-LM: 113.0 s (IQR: 86.3-148.8 s); p < 0.001), both were also rated as slightly easier to perform in the extensors (ARPE-EX: 13 (IQR: 12.0-14.0) vs BRPE-EX: 11 (IQR: 10.0-13.0); pRPE-EX < 0.001) and lateral muscles testing (ARPE-LM: 14.0 (IQR: 12.3-15.8) vs. BRPE-LM: 13.0 (IQR: 12.0-15.0); pRPE-LM = 0.001). A and B tests are comparable in three of four trunk muscle endurance ratios, while longer holding times and lower perceived effort to perform were observed in most of the B tests. The Roman chair tests could be used as an alternative to standard tests.

Upper Extremity Muscle Activation during Drive Volley and Groundstroke for Two-Handed Backhand of Female Tennis Players.

Drive volley is one of the essential backhand stroke technique trends seen in recent women's tennis competitions. Although movements of the drive volley and groundstroke are similar, activation of the internal muscles vary due to different incoming ball conditions. Most previous studies only focused on the groundstroke, however. The current study investigates the different muscle activation patterns in the upper extremity muscle during the two-handed backhand drive volley as well as the groundstroke for female tennis players. Ten elite female tennis players were measured in the muscle activation of the flexor carpi radialis (FCR), extensor carpi radialis (ECR), biceps brachii (BB), and triceps brachii (TB) from both upper extremities. Racket-head speed at impact, swing duration of each phase, and racket-head average velocity in both strokes were also recorded. Significant differences were found between the drive volley and groundstroke in the velocity profile of racket tip, swing duration of each phase (preparation, early follow-through, and late follow-through), activation patterns of upper extremity muscles, and flexor/ extensor ratios of wrist and elbow in both upper extremities. Different racket trajectory strategies were also observed between the two strokes, with greater horizontal racket velocity recorded in the groundstroke but greater vertical velocity in the drive volley. ECR and TB muscle activation during the drive volley preparation phase was greater than the groundstroke when completing a quicker backswing. In the early acceleration phase, the greater FCR leading arm activation in the drive volley assisted wrist stabilization in preparation for impact. In the late follow-through phase, less TB leading arm activity and higher ECR trailing arm activity in the drive volley showed more forward compression movement in racket contact with the ball. As it is essential for the drive volley to complete a quicker backswing and to increase shot efficiency at the end of the forward movement, coaches should consider the two strokes' muscle activation and technique differences to enhance specific techniques and fitness training programs.

Effectiveness of Warm-Up Exercises with Tissue Flossing in Increasing Muscle Strength.

Tissue flossing is an increasingly popular method in physiotherapy and sports. There is a belief that tissue flossing can improve range of motion and muscle strength, shorten muscle recovery time, and reduce the risk of injury. The aim of this study was to analyse the effectiveness of tissue flossing for immediately improving muscle strength in recreational athletes when it is performed during warm-up. All participants were randomly assigned to either an experimental group (n = 36) or a control group (n = 34) using a random number generator. The experimental group (n = 36) performed an intervention comprising exercises with muscle tissue flossing and exercises without flossing. The control group (n = 30) performed the same protocol without a floss band. Muscle strength was measured for knee flexion end extension at three speeds (60, 120, and 180 °/s) 3 times. Analysed parameters include peak torque, work, and power related to body weight, flexors–extensors ratio, and time to peak torque. There were no significant changes in the muscle strength parameters from before to after the warm-up in either group (p > 0.05). Significantly lower values of peak torque, work, and power were observed in the experimental group during the warm-up with the floss band applied to muscles (p < 0.05). No clinically significant changes in time to peak torque or flexors–extensors ratio were observed. A single application of flossing does not improve muscle strength or power and can even reduce individuals’ maximum muscle strength capabilities.

Muscle Quality and Functional and Conventional Ratios of Trunk Strength in Young Healthy Subjects: A Pilot Study.

Background: The trunk strength conventional ratio (CR) has been evaluated. However, the functional ratio and the ratio of strength to body weight (BW) or muscle mass (MM) have been poorly explored. Relative strength is a measure of muscle quality. Objectives: To analyze the trunk strength ratio normalized by BW and MM and compare the trunk’s conventional and functional ratios collected in isokinetic and isometric conditions. Methods: Twenty-seven healthy males (21.48 ± 2.08 years, 70.22 ± 7.65 kg) were evaluated for trunk isometric and isokinetic strength using a functional electromechanical dynamometer. Results: The extensor’s strength was greater than the flexors, with a CR of 0.41 ± 0.10 to 0.44 ± 0.10. Muscle quality was higher in eccentric contraction and high velocity for flexors and extensors. The functional flexor ratio (FFR) ranged between 0.41 ± 0.09 and 0.92 ± 0.27. The functional extensor ratio (FER) ranged between 2.53 ± 0.65 and 4.92 ± 1.26. The FFR and FER showed significant differences between velocities when considering the peak strength (p = 0.001) and mean strength (p = 0.001). Conclusions: Trunk extensors were stronger than the flexors; thus, the CR was less than one. Muscle quality was higher at a high velocity. Unlike CR, FFR and FER behaved differently at distinct velocities. This finding highlights the need to explore the behavior of the functional ratio in different populations.

Reliability of a neck strength test in schoolboy rugby players

BackgroundIn rugby union, a bracing mechanism of the neck and trunk is normally adopted in contact situations where high linear and angular forces are produced, which may contribute to the risk for sports-related concussion (SRC). ObjectivesTo examine the feasibility of and test-retest reliability, both inter-rater and intra-rater reliability, of a novel neck strength test in schoolboy rugby players and to summarize neck strength values for this cohort, including rugby position-specific estimates. Materials and methods52 male schoolboy rugby union players completed the neck strength test protocol twice, eight days apart using a novel device. ResultsIntra-class correlation coefficients (ICCs) were good to excellent for test-retest reliability (range from 0.86 to 0.92) in all four directions. Intra-rater (ICCs range from 0.706 to 0.981) and inter-rater (ICCs range from 0.669 to 0.982) ranges were calculated. Significant differences were identified between forwards and backs for non-normalised force measures but no significant difference when normalised to bodyweight. The flexor:extensor ratio was 0.68 (SD 0.2) for forwards, 0.71 (SD 0.16) for backs and 0.67 (SD 0.16) for the cohort. Discussion & conclusionWhile there is limited direct evidence to support a direct link between neck strength and SRC risk at present, investigating the relationship of neck strength, stiffness and impact anticipation might be a useful direction for further research. In conclusion, we describe a portable, user-friendly and safe neck strength test with good-to-excellent test-retest reliability, and intra-, inter-rater reliability. Test-retest ICC values compare favourably to gold standard fixed-frame dynamometry and are superior to hand-held dynamometry.

Analyses of Isokinetic Thigh Muscle Strength: Camera-Based Assessment Alters the Magnitude, but Not the Message

ABSTRACT Background: Thigh muscle strength capacities are major modifiable risk factors for knee and thigh muscle injuries. Therefore, their valid assessment is essential. Most isokinetic knee tests are conducted in a seated position and rely on dynamometer-based data. However, their accuracy is doubtful because axis alignment is erroneous. Purpose: This study investigated if hip angle (flexed vs. extended) and assessment method (dynamometer-based vs. camera-based) affect isokinetic outcome parameters. Methods: Sixteen healthy male participants (27 years, 184 cm, 80 kg) performed discrete isokinetic tests of the knee flexors and extensors (60°/s) while their kinematics were captured (100 fps). Results: Both assessment methods revealed very strong linear relationships (94% ≤ R 2 ≤ 98%) although peak moments (d ≤ 0.87), contractional work (d ≤ 1.26), and functional knee flexor:extensor ratios (d ≤ 0.81) significantly differed. Seated knee flexor tests demonstrated the largest knee trajectory center’s misalignment (x = 4.0 cm, z = −2.5 cm; 1.37 ≤ d ≤ 4.74). Conclusion: Hip-angle induced kinematic changes did not affect the relation between the lever arms, thus causing highly proportional deviations of kinetic parameters. The assessment method altered the magnitude, but not the message of isokinetic knee tests, which should be preferentially performed with extended hip joint to improve axis alignment. Knowledge of these kinetic and kinematic interactions assists practitioners and scientists with isokinetic tests and/or rehabilitation training to ensure reasonable interpretations of gathered isokinetic outcomes.

Cervical Flexor-Extensor Muscle Disparity in Monomelic Amyotrophy (Hirayama Disease): Evidence from a Comprehensive Morphometric Evaluation of Subaxial Paraspinal Musculature.

Background Monomelic amyotrophy (Hirayama disease) has been established to have accompanied biomechanical abnormalities such as flexion hypermobility and sagittal imbalance. Paraspinal muscles, the major contributor to cervical biomechanics, have, however, not been comprehensively evaluated in the disease. The objective of this study was to compare the morphology of the subaxial cervical paraspinal musculature in patients with and without Hirayama disease. Materials and Methods A retrospective case-control study of 64 patients with Hirayama disease and 64 age- and sex-matched controls was performed . Cross-sectional areas (CSAs) of the superficial and deep flexors and extensors from C3 to C7 were measured on T2-weighted magnetic resonance imaging sequences. Student's t -test was used to compare differences between the paraspinal muscle CSAs in the study and control groups. Results Compared with controls, patients with Hirayama disease were found to have larger flexors and smaller extensors at all levels. The overall subaxial muscle area values for superficial flexors and deep flexors were significantly larger ( p < 0.0001) in patients, while the corresponding superficial extensor and deep extensor area values were significantly smaller than in controls ( p = 0.01 and < 0.0001, respectively). The patient group demonstrated stronger subaxial deep flexor–deep extensor, superficial flexor–superficial extensor, and total flexor–total extensor ratios ( p < 0.0001). Conclusion Patients with Hirayama disease have morphometric alterations at all levels of their subaxial cervical paraspinal musculature. These patients have abnormally large flexors and small extensors compared with controls. This flexor–extensor muscle disparity could be utilized as a potentially modifiable factor in the management of the disease.

The comparative research of basic and professional fitness levels between national team taolu and sanda

Purpose The purpose of this study was to find out the physical characteristics of Wushu athletes by comparing the differences on the results of physical fitness between the male athletes of the Wushu national team Taolu and the Sanda group. Methods Measurement of basic and professional fitness based on muscle function, targeting 37 men Wushu national team players (24 taolu, 13 Sanda) in the selection and evaluation contests twice in 2018 and 2019. Body composition, isometric muscle strength, flexibility and equilibrium, anaerobic power, and isokinetic muscle strength. The fitness factors were divided into two groups, Taolu and Sanda. Results First, body fat rate of the Sanda athlete group was significantly lower than that of the taolu athlete group (p&lt;.01). Second, in the isometric muscle strength category(back muscle strength, grip strength), the Sanda athlete group had higher muscle strength than Taolu athlete group, but there was a statistically significant difference only in the left grip strength (p&lt;.01). Third, in terms of flexibility and equilibrium, the taolu players were significantly higher in all items(p&lt;.001). Fourth, in the anaerobic power, the taolu athlete group had higher both the peak power and the mean power, and there were a significant differences(peak power: p&lt;.01, mean power: p&lt;.001). Fifth, isokinetic muscle strength was significantly higher in the right knee flexion of the taolu athlete group (p&lt;.01), and lumbar extensor muscle was significantly higher in the Sanda athlete group (p&lt;.05). Sixth, in the isokinetic strength ratio, the knee flexion ratio of the Sanda athlete group were significantly higher on the left and right knee flexion and extensor ratios (p&lt;.05). In addition, in the lumbar flexor and extensor ratios, the group of Sanda athlete group were significantly higher on the lumbar extensor(p&lt;.05). Seventh, there was no significant difference between two groups in isokinetic muscle power. Conclusions The results of this study can be used as basic data to improve the efficiency of technical and physical training through the analysis of the characteristics of Taolu and Sanda. The effectiveness of this training will help to improve the performance.

Determination of Predictive Isokinetic Indicators for Return to Sport at 6 Months after ACL Surgery with Semitendinous and Gracilis Tendons

Background: Numerous evaluation criteria are found in the literature to determine the resumption of sport in patients with anterior cruciate ligament (ACL) surgery. Nevertheless, no consensus can conclude today on precise indicators to determine the return to sport (RTS) at 6 months after ACL surgery. Aim: The purpose of this study is to determine whether isokinetic evaluation has indicators representative of the functional status of the knee after ACL surgery with semitendinosus and gracilis tendons (STG) to RTS. Methods: Twenty-two patients, 6.2 months after ACL surgery with STG participated in the study. A correlation was sought between the International Knee Documentation Committee (IKDC) subjective form and the following isokinetic parameters for flexors and extensors at angular velocities of 60°/s and 240°/s: Peak Torque (PT), Flexors /Extensors ratio, PT/kg, and the total work. Results: The statistical analysis found significant correlations between the IKDC subjective form is PT/ kg, PT and total work with the exception of 60°/s flexors. No correlation was found for the flexor / extensor ratio. Conclusion: PT, PT/kg, total work of extensors and flexors at 240°/s and extensors at 60°/s appear to be the best indicators of knee functional status for sports recovery after ACL surgery

Deep flexor sarcopenia as a predictor of poor functional outcome after anterior cervical discectomy in patients with myelopathy.

Paraspinal muscle morphometry has been recognized to be a prognostic factor across various surgical conditions, but its utility in predicting disease-specific outcomes in spine surgery remains under-explored. A prospective cohort study was performed on 45 consecutive patients undergoing anterior cervical discectomy (ACD) for single-level, symptomatic cervical degenerative disc disease causing radiculomyelopathy or myelopathy. Previously described predictors of outcome such as age, gender, smoking, comorbidities, duration of symptoms, preoperative Nurick grade, extent of cord compression, and signal intensity change in the cord were recorded. Additionally, MRI-based morphometrics of the superficial and deep paraspinal muscles were recorded. Logistic regression (LR) analysis was performed using a purposeful variable selection process to identify variables that independently predicted Nurick grade improvement (NGI). At a mean follow-up of 20.02 ± 8.63months after ACD, 37 (82.22%) patients demonstrated NGI. LR analysis yielded three predictors of NGI of which two were related to the deep flexor muscles. While a worse preoperative Nurick grade negatively predicted NGI, a deep flexor area and deep flexor/deep extensor area ratio positively predicted NGI. The regression model demonstrated a good fit and was statistically significant (χ2(3) = 22.18, p < 0.0001). The model explained 64% of the variance in NGI and correctly classified 89% of cases. This study has for the first time identified the utility of paraspinal morphometrics in predicting disease-specific functional outcome after cervical spine surgery. Our results indicate that in addition to preoperative Nurick grade, an already accepted outcome predictor, the deep flexor cross-sectional area, and the deep flexor/deep extensor ratio are strong predictors of NGI following ACD for single-level, symptomatic cervical degenerative disc disease with myelopathy. Deep muscle morphometrics could be included in future risk stratification algorithms for patients with cervical disc disease.

Characteristics of individual thigh muscles including cross-sectional area and adipose tissue content measured by magnetic resonance imaging in knee osteoarthritis: a cross-sectional study.

This study aimed to identify the parameters related to the area and adipose tissue content of thigh muscles that are associated with radiographic knee osteoarthritis grade. Fifty patients (mean age ± standard deviation, 73.0 ± 4.5years) were divided into early osteoarthritis (n = 23) and established osteoarthritis (n = 27) groups based on Kellgren-Lawrence classification. The femorotibial angle was measured from anteroposterior radiographs of the lower limbs. Individual thigh muscle and adipose tissue areas were analyzed using axial T1-weighted magnetic resonance imaging. After intergroup comparison, logistic regression analysis was performed to determine independent parameters associated with established osteoarthritis. Moreover, correlation coefficients were assessed between the left-right differences of osteoarthritis grade and parameters. Established osteoarthritis exhibited a significantly greater femorotibial angle and increased adipose tissue content in the subcutaneous, intermuscle, and intramuscle of the adductor, vastus lateralis, vastus intermedius, as well as a lower vastus medialis area, in comparison to early osteoarthritis. A greater femorotibial angle, increased intermuscular adipose tissue, and a lower vastus medialis area to knee extensor ratio were significantly independently associated with established osteoarthritis (odds ratio 3.2, 1.8, and 2.0, respectively). The left-right differences of femorotibial angle and vastus medialis area were significantly correlated with osteoarthritis grade, whereas adipose tissue content had no significant correlations with osteoarthritis grade. Greater femorotibial angle and lower vastus medialis area were related with higher osteoarthritis grade. Greater intermuscular adipose tissue content was associated with established osteoarthritis; however, in the left-right differences, adipose tissue content was not related with osteoarthritis grade.

Influence of Isokinetic Knee Muscle Torque at Different Angular Velocities on Standing Posture Stability in Healthy Adults

Abstract Objectives Knee muscle groups contribute to proper and safe static and dynamic standing posture stability. The impact of isokinetic knee muscle torque at various angular velocities on standing posture stability is poorly understood. We investigated the influence of isokinetic knee muscle torque at different angular velocities on standing posture stability. Design Cross-sectional study. Setting King Saud University Campus labs. Method The study population was a convenience sample of 30 healthy volunteer college students with a mean age of 20±2 years. Isokinetic concentric peak torque (PT) of knee extensor (Q) and flexor (H) muscle groups as well as the flexor to extensor (H:Q) ratio at three different angular velocities: (60, 180, and 300°/s) were measured, respectively. The postural stability was also measured in both static and dynamic components. The Pearson correlation coefficient was used to examine the association between the different isokinetic components and postural stability (both static and dynamic). Results The PT of Q and H muscle groups and the H:Q ratio at the 3 different angular velocities were significantly associated with static standing balance with eye open on a firm surface (p&lt;0.033). Moreover, the PT of Q at 60 and 180°/s angular velocities was significantly associated with maximum and endpoint excursion components of dynamic standing balance (p&lt;0.044). Conclusions The PT of both Q and H muscle groups at different angular velocities are associated with maintenance of standing static balance. PT of Q only is significantly associated with control of dynamic standing balance in the lower angular velocities.

Effect of Muscular Strength, Asymmetries and Fatigue on Kicking Performance in Soccer Players.

The aim of this study was to determine the effect of muscular strength, strength asymmetries, and fatigue on the speed and accuracy of an instep kick in soccer players. We measured ball velocity (BV) and kicking accuracy (KA) in the preferred (PL) and non-preferred leg (NPL) before (PRE) and after (POST) physical load in the PL. Maximum peak muscle torque of the knee extensors and flexors in the PL and NPL as well as ipsilateral knee flexors and knee extensors ratio (H:Q ratio) for both legs were assessed. BV was significantly decreased in POST physical load (5.82%, BVPRE=30.79±1.70 m·s-1, BVPOST=29.00±1.70 m·s-1, t19=3.67, p=0.00, d=1.05). Instep kick accuracy after the physical load worsened by an average of 10% in the most accurate trials. Results revealed a significant decrease in instep kick accuracy after physical loading (KAPRE=2.74±0.70 m, KAPOST=3.85±1.24 m, t19=-3.31, p=0.00, d=1.10). We found an insignificant correlation between H:Q ratio and KA in PRE test value, whereas a lower ipsilateral ratio (higher degree of strength asymmetry) in the POST physical load significantly correlated with KA in all angular velocities (r=-0.63 up to -0.67, p=0.00).

INJURY INCIDENCE IN CROSS-COUNTRY SKIERS

BackgroundProspective, cross-country ski injury incidence data is scarce.ObjectiveTo describe injury type and incidence sustained by elite cross-country skiers in north-eastern America. We hypothesized that lower extremity injury incidence would be...

Effect of Whole-Body-Vibration Training on Trunk-Muscle Strength and Physical Performance in Healthy Adults: Preliminary Results of a Randomized Controlled Trial

Whole-body-vibration (WBV) stimulus equipment has been used as a new training method for health promotion. Its use in the clinic has expanded to the field of sports and rehabilitation for disabled patients. WBV training is rapidly gaining popularity in health and fitness centers as an alternative method for improving muscle performance. Acute positive effects of WBV have been shown on lower-extremity muscle power and vertical-jump ability; however, there have not been any studies focusing on the long-term effects of WBV for trunk muscle and dynamic balance. To investigate the effects of an 8-wk program of WBV in combination with trunk-muscle training on muscle performance in healthy, untrained adults. Laboratory-based, repeated-measures study. University laboratory. 20 healthy university men. Participants were randomly assigned to a WBV or non-WBV group. The WBV group performed a trunk-muscle-training program in combination with WBV; the non-WBV group performed the same muscle-training program without WBV for 8 wk. In the pre- and posttraining period, the participants were evaluated using the Functional Movement Screen (FMS), Y Balance Test (Y-test) (anterior, posteromedial, and posterolateral reach), trunk-muscle isometric strength (flexor, extensor, and flexor:extensor ratio), squat jump, and countermovement jump. The WBV group had greater improvement than the non-WBV group in both trunk-flexor muscle strength (P = .02) and the Y-test (anterior reach) (P = .004) between pre- and posttraining. Adding WBV to a trunk-muscle-strengthening program may improve trunk-flexor isometric strength and anterior reach during the Y-test more than training without WBV. The WBV protocol used in this study had no significant impact on FMS scores, squat jumping, countermovement jumping, trunk-extensor isometric strength, or trunk flexor:extensor ratio.

MRI-determined lumbar muscle morphometry in man and sheep: potential biomechanical implications for ovine model to human spine translation

The sheep is a commonly used animal model for human lumbar spine surgery, but only in vitro investigations comparing the human and ovine spine exist. Spinal musculature has previously not been compared between man and sheep. This additional knowledge could further indicate to what extent these species are biomechanically similar. Therefore, the purpose of the study was to investigate spinal muscle morphometric properties using magnetic resonance imaging (MRI) in different age groups of healthy human participants and sheep in vivo. Healthy human participants (n = 24) and sheep (n = 17) of different age groups underwent T1-weighted MRI of the lumbar spine. Regions of interest of the muscles erector spinae (ES), multifidus (M) and psoas (PS) were identified. The ratio of flexor to extensor volume, ratio of M to ES volume, and muscle fat relative to an area of intermuscular fat were calculated. Sheep M to ES ratio was significantly smaller than in the human participants (sheep 0.16 ± 0.02; human 0.37 ± 0.05; P < 0.001), although flexor to extensor ratio was not significantly different between species (human 0.39 ± 0.08; sheep 0.43 ± 0.05; P = 0.06). Age did not influence any muscle ratio outcome. Sheep had significantly greater extensor muscle fat compared with the human participants (M left human 40.64%, sheep 53.81%; M right human 39.17%, sheep 51.33%; ES left human 40.86%, sheep 51.29%; ES right human 35.93%, sheep 44.38%; all median values; all P < 0.001), although PS did not show any significant between-species differences (PS left human 36.89%, sheep 33.67%; PS right human 32.78%, sheep 30.09%; P < 0.05). The apparent differences in the size and shape of sheep and human lumbar spine muscles may indicate dissimilar biomechanical and functional demands, which is an important consideration when translating to human surgical models.

Isokinetic trunk strength in the teenagers with and without low-back pain: a comparative study

Results No significant difference was found between isokinetic peak torque, total work and mean power in extension and flexion in the two groups. Other than, the control group had a higher mean power extension in 120°/s than the LBP group with a nearly significant p. Significant correlations between isokinetics total work at 120° in flexion (r=0,461) and in extension (r=0,475) were observed with the body mass index. A high correlation was also found between the total work at 120° in extension (r=0,668) and the number of hours per week of sport activities. The mean power in extension at 120°/s was correlated positively (r=0,453) to the lumbar radiological lordosis. The endurance of agonist (flexors) and antagonist (extensors) ratio was high in both populations compared to the expected values in general population (0,91 vs 0,89).

Neuromuscular adaptations induced by a short rehabilitation program in chronic low back pain

Significant correlations between isokinetics total work at 120◦/s in flexion (r = 0.461) and in extension (r = 0.475) were observed with the body mass index. A high correlation was also found between the total work at 120◦/s in extension (r = 0.668) and the number of hours per week of sport activities. The mean power in extension at 120◦/s was correlated positively (r = 0.453) to the lumbar radiological lordosis. The endurance of agonist (flexors) and antagonist (extensors) ratio were high in both populations compared to expected values in general population (0.91 vs 0.89). Conclusion.– This study reveals no significant difference in the isokinetic trunk strength of both flexors and extensors in the two groups. Based on the results, the usefulness of studying the effect of isokinetic rehabilitation is to remove the inhibition at high speed. So, isokinetic strength parameters, as measured in this study, do not seem to explain the occurrence of low back pain among children. ReferencesExercise reduces the intensity and prevalence of low back pain in 12–13-year-old children: a randomised trial. Gina L Fanucchi, Aimee Stewart et al. Australian Journal of Physiotherapy 2009;55:97–104.The Association between isoinertial trunk muscle performance and low back pain in male adolescents. Federico Balague, Evelyne Bibbo et al. Eur Spine Journal 2010;19;624–32.