Functional Strength Ratios Research Articles

Asymmetry of conventional and functional strength ratios in youth male taekwondo players

Asymmetry of conventional and functional strength ratios in youth male taekwondo players

Functional Ipsilateral and Bilateral Strength Ratios in Young Elite Athletes Across Multiple Sports Disciplines

This research investigates functional strength ratios in young elite athletes across different sports disciplines with different movement characteristics, focusing on the relationship between these ratios and physical performance. Purpose: the study aims to examine the differences in functional ipsilateral and bilateral strength ratios among athletes in symmetrical, asymmetrical, and hybrid sports and assess how these disparities impact strength parameters. Material & Methods: the study comprised 56 male athletes aged 18-28, excluding those with lower limb injuries or limitations affecting performance. The participants were divided into symmetrical, asymmetrical, and hybrid sports categories. Strength assessment utilised an isokinetic dynamometer, focusing on quadriceps-to-hamstring strength and bilateral strength ratios. The study employed MANOVA as the major statistical test for the purpose of the study. Results: athletes in asymmetrical sports demonstrated higher bilateral symmetry in knee extensors compared to symmetrical (0.94±5.98) and hybrid sports (4.9±10.32), with values of 12.89±8.56. The functional hamstring to quadriceps (H:Q) strength ratio showed lower ratios in hybrid sports (right limb: 0.60±0.12, left limb: 0.61±0.09) compared to symmetrical (right limb: 0.79±0.16, left limb: 0.94±0.27) and asymmetrical sports (right limb: 1.05±0.26, left limb: 1.03±0.24), yet within normative values. These findings suggest that sport-specific demands significantly influence functional strength ratios, highlighting the importance of tailored training and rehabilitation programs. The observed strength asymmetries, particularly in sports with unilateral movements, underline the need for sport-specific training approaches to address these imbalances. Conclusion: the study revealed that sport-specific training can lead to strength asymmetries within normal ranges, suggesting that they may not substantially induce muscular imbalances. However, the distinct H:Q ratio patterns in hybrid sports emphasise the need for customised training and rehabilitation strategies.

Effects of a Football Simulated Exercise on Injury Risk Factors for Anterior Cruciate Ligament (ACL) Injury in Amateur Female Players.

Females are more at risk of Anterior Cruciate Ligament (ACL) injuries than males; however, there is limited literature on neuromuscular risk factors such as angle-specific hamstring/quadriceps functional strength ratios (Hecc/Qcon) and rate of torque development (RTD) in female footballers. The aim of this study was to investigate the effects of fatigue on these neuromuscular risk factors. Thirty-three amateur players (20.3 ± 2.0 years old, 1.67 ± 9.31 m, 63.4 ±8.1 kg, 23.6 ± 5.7% body fat) performed strength assessments of the quadriceps (concentrically, Qcon) and hamstrings (eccentrically, Hecc) on both legs on an isokinetic dynamometer, before and immediately after a football-specific exercise. Results showed significantly lower peak Hecc (-15.1 to -15.5%), peak Hecc/Qcon (-8.8 to -12.9%) and RTD (-14.0 to -17.0%) for hamstring eccentric contractions after fatigue in the dominant and non-dominant legs. Furthermore, significant decreases in Hecc/Qcon were observed at 10° only in the dominant leg (-15.5%), and at 10°, 20° and 30° in the non-dominant leg (-15.1 to -21.8%). These results suggest a reduced capacity of the hamstrings to stabilise the knee joint with fatigue. Unlike results previously shown on men, the non-dominant leg seemed more affected, highlighting the need to consider specific prevention measures in females.

Clinical shoulder measurements related to joint loads in collegiate pitchers

Pitchers are prone to upper extremity injury due to repetitive high joint loads. Clinical measures of shoulder strength and range of motion (ROM) have shown links to injury risk in pitchers, however, these factors have rarely been studied in relation to throwing joint loads. The purpose of this study was to identify which clinical ROM and isokinetic strength variables were related to peak shoulder and elbow joint torques in collegiate pitchers. Thirty-three healthy collegiate pitchers participated in this study. Fastball velocity, shoulder concentric and eccentric strength, and passive shoulder ROM variables were analyzed using a Lasso regression to determine what factors influenced shoulder internal rotation torque and elbow varus torque. Fastball velocity was selected by the Lasso as indicator of increased shoulder and elbow torque. Passive shoulder external rotation ROM was also selected as an important factor in joint loading with increased shoulder external rotation ROM being related to lower joint loads. The bilateral ratio of shoulder internal rotator concentric strength was related to peak shoulder and elbow torques with an increase in the bilateral ratio of shoulder strength leading to reduced joint torques. Increases in the eccentric external rotator to concentric internal rotator strength (functional ratio) of the dominant arm and increases in dominant arm eccentric internal rotator strength were both related to increases in each joint torque. Results from the study indicate that pitch speed, passive shoulder external rotation ROM, and the isokinetic shoulder strength profile including internal rotator strength and functional strength ratio of pitchers are related to joint loading during the pitch and may be important to monitor in relation to injury risk and/or during rehabilitation. These results provide insight into the role that both shoulder ROM and rotator cuff strength play in the dynamic stabilization of the elbow and shoulder during pitching.

Shoulder Isokinetic Strength Balance Ratio in Overhead Athletes: A Cross-Sectional Study.

BackgroundStudies have grouped different overhead sports and evaluated together the isokinetic strength of shoulder internal (IR) and external (ER) rotator muscles. However, muscular adaptations could be a consequence of the specific sport, and some strength imbalance between these muscles may exist as a consequence of the muscular demand unique to the sport. Therefore, grouping different overhead sports together may not be adequate.PurposeTo compare strength balance ratios between different overhead sports (volleyball, handball, swimming, judo, baseball, softball, functional movements performed at high-intensity interval training, and tennis) with a control athletic group (no overhead group).Study designCross-sectional study.MethodsA total of 237 athletes were submitted to isokinetic shoulder strength tests. The isokinetic concentric and eccentric peak torque values of shoulder internal IR and external ER rotator muscles were measured. Conventional (CR) and functional strength ratios (FR) were calculated.ResultsThere were no significant differences between the sports for the CR in the male group. Female softball athletes (90.4±13.6%) had a significantly higher CR than judo (67.3±6.9%), volleyball (74.9±15.9%), and swimming athletes (70.3±8.7%). In the female group, judo athletes had lower FR values (0.76±0.19) than soccer athletes (1.31±0.35), volleyball athletes (1.24±0.27), functional movements performed at high intensity (1.10±0.1), and softball athletes (1.40±0.39). Female handball athletes also had a lower FR (0.99±0.25) than soccer athletes (1.31±0.35) and softball athletes (1.40±0.39). Male handball (0.90±0.23), tennis (0.86±0.30), and judo (0.68±0.22) athletes had lower FR values than soccer athletes (1.20±0.21) and volleyball athletes (1.25±0.28).ConclusionsCR for males may be analyzed together, as there were no significant differences between them. However, for females, the CR for softball athletes should be analyzed individually. As there were several differences between the overhead sports according to the FRs, the authors suggest caution in grouping overhead athletes across multiple sports. These results could have important implications for the design of injury prevention and rehabilitation programs associated with the shoulder joint in overhead sports.Level of Evidence3

Cutoffs of isokinetic strength ratio and hamstring strain prediction in professional soccer players.

Hamstring strain injuries frequently occur during professional soccer practice. Low hamstring strength represents an intrinsic modifiable risk factor but cutoffs of isokinetic knee strength ratios are controversial to predict hamstring strain in professional soccer players. We aimed to predict hamstring strain in accordance with cutoffs of isokinetic knee strength ratios. Bilateral, conventional, and functional isokinetic strength ratios were calculated in 194 professional soccer players at the beginning of 15 consecutive seasons. 36 soccer players presented a moderate hamstring strain and 158 were not injured. The different calculated isokinetic ratios were compared with the right and left limb of the uninjured population. Different usual cutoffs were tested: at 0.85 and 0.90 for the bilateral concentric and eccentric hamstring-to-hamstring ratio, at 0.60 and 0.47 for the conventional hamstring-to-quadriceps ratio and at 0.80 and 1 for the mixed hamstring-to-quadriceps ratio. The specific ratios for the studied population were also determined by the 10th percentile and then tested. Hamstring strain prediction was established in terms of odds ratios. No cutoff with bilateral, conventional, or functional isokinetic strength ratio was predictive of hamstring strain after univariate analysis. Specific cutoffs determined from the studied population were not more predictive. Very few injured soccer players presented values under the cutoffs at 0.47 for the conventional ratio and at 0.80 for the mixed ratio. Regardless of their values, cutoffs of isokinetic strength ratios were not predictive of hamstring injuries. The use of isokinetic cutoffs is not recommended to predict hamstring muscle strain in professional soccer players.

Strength and size relationships of the quadriceps and hamstrings with special reference to reciprocal muscle balance.

This study examined the association of muscle size and strength for the quadriceps and hamstrings, the relationship between the size of these muscles, and whether the H:Q size ratio influenced reciprocal strength balance-widely regarded as a risk factor for hamstrings injury. Knee extensor and flexor isometric, concentric and eccentric (50 and 350° s(-1)) strength were measured in 31 healthy, recreationally active young men. Muscle volume was measured with magnetic resonance imaging. The knee flexors achieved higher concentric and eccentric torques (normalised to isometric values) than the extensors. Muscle volume explained a significant part of the inter-individual differences in strength in both extensors (isometric 71%, concentric 30-31%) and flexors (isometric 38%, concentric 50-55%). Notably, muscle size was related to knee flexor eccentric strength (r = 0.69-0.76; R (2) = 48-58%) but not extensor eccentric strength. Quadriceps and hamstrings volumes were moderately correlated (r = 0.64), with the majority of the variance in the size of one muscle (59%) not explained by the size of the other muscle. The hamstrings-to-quadriceps (H:Q) volume ratio was correlated with the isometric (r = 0.45) and functional strength ratios (350° s(-1), r = 0.56; 50° s(-1), r = 0.34). Muscle size exhibited a differential influence on knee extensor and flexor eccentric strength. Quadriceps and hamstrings muscle size was related, and the H:Q size ratio contributed to their strength ratios. Muscle size imbalances contribute to functional imbalances and these findings support the use of hamstrings strength training with an emphasis on hypertrophic adaptations for reducing injury risk.

Reliability of concentric and eccentric strength of hip abductor and adductor muscles in young soccer players.

The concentric and eccentric strength profile and muscular balance of the hip joint are important parameters for success in soccer. This study evaluated the reliability for the assessment of hip abduction and adduction isokinetic strength over a range of angular velocities (30 and 90°/s) and types of muscular actions (concentric and eccentric) in young soccer players. The reliability for the assessment of reciprocal (conventional and functional) and bilateral torque ratios was also examined. Fifteen male soccer players (15±1 years) performed two sessions, separated by three days. The testing protocol consisted of five maximal concentric and eccentric hip abductions and adductions of both legs at angular velocities of 30°/s and 90°/s. The peak torque was evaluated in young soccer players using an isokinetic dynamometer (Cybex Norm), and the reciprocal strength ratios (conventional and functional) and bilateral ratios (non-preferred to preferred leg ratios) were calculated. The test-retest reliability for the assessment of peak torque (ICC = 0.71-0.92) and of reciprocal muscle group ratios (ICC = 0.44-0.87) was found to be moderate to high. Bilateral torque ratios exhibited low to moderate reliability (ICC = 0.11-0.64). In conclusion, isokinetic strength of hip abductor and adductor muscles and the conventional and functional strength ratios can be reliably assessed in young soccer players, especially at low angular velocities. The assessment, however, of bilateral strength ratios for hip abductor/adductor muscles should be interpreted with more caution.

Lower-extremity strength ratios of professional soccer players according to field position.

Previous investigators have proposed that knee strength, hamstrings to quadriceps, and side-to-side asymmetries may vary according to soccer field positions. However, different results have been found in these variables, and a generalization of this topic could lead to data misinterpretation by coaches and soccer clubs. Thus, the aim of this study was to measure knee strength and asymmetry in soccer players across different field positions. One hundred and two male professional soccer players performed maximal concentric and eccentric isokinetic knee actions on the preferred and nonpreferred legs at a velocity of 60° · s. Players were divided into their field positions for analysis: goalkeepers, side backs, central backs, central defender midfielders, central attacking midfielders, and forwards. Results demonstrated that only goalkeepers (GK) differed from most other field positions on players' characteristics, and concentric peak torque across muscles. Although all players presented functional ratios of the preferred (0.79 ± 0.14) and nonpreferred (0.75 ± 0.13) legs below accepted normative values, there were no differences between positions for conventional or functional strength ratios or side-to-side asymmetry. The same comparisons were made only between field players, without inclusion of the GK, and no differences were found between positions. Therefore, the hamstrings to quadriceps and side-to-side asymmetries found here may reflect knee strength functional balance required for soccer skills performance and game demands across field positions. These results also suggest that isokinetic strength profiles should be considered differently in GK compared with other field positions due to their specific physiological and training characteristics.

Isokinetic Rotator Cuff Functional Ratios and the Development of Shoulder Injury in Collegiate Baseball Pitchers

Context:Shoulder injury in baseball pitchers is a very common problem and has been linked to an imbalance in rotator cuff strength. Recently, the use of functional shoulder strength ratios has become more popular because they more closely resemble the actions of the shoulder during the throwing motion.Objective:To investigate the link between preseason shoulder rotator cuff functional strength ratios and the development of shoulder pain and injury.Design:Prospective research design.Setting:University human performance laboratory.Patients:Fifteen collegiate baseball pitchers participated in this study. At the end of the baseball season, six (19.5 ± 1.8 years, 73.6 ± 2.8 inches, 198.7 ± 19.1 lbs) developed shoulder injury and were placed in the injured group, and nine (21.0 ± 1.7 years, 73.1 ± 2.3 inches, 207.9 ± 28.1 lbs) did not develop injury and were placed in the noninjured group.Interventions:Isokinetic peak torque was collected concentrically and eccentrically for both shoulder internal rotation (IR) and external rotation (ER) at 60°-s−1, 180°-s−1, and 300°-s−1.Main Outcome Measure:The following functional ratios were calculated from the peak torque measures: concentric ER: concentric IR; eccentric ER: eccentric IR; concentric ER: eccentric IR (cocking phase); and eccentric ER: concentric IR (acceleration phase). Analysis was conducted using an analysis of variance comparing the injured and noninjured groups. A secondary analysis was conducted using an analyses of variance on the concentric and eccentric peak torque for shoulder IR and ER between groups.Results:The acceleration phase functional shoulder ratio was significantly higher (p = .019) in the injured group and a concentric IR peak torque (p = .003) was significantly lower in the injured group compared with the noninjured group.conclusion:Increased acceleration phase ratios and decreased concentric IR peak torque may be linked to the development of shoulder injury during a baseball season.

Muscle fatigue induced by a soccer match-play simulation in amateur Black South African players

The purpose of the current study was to investigate the effects of a soccer-specific fatigue protocol on the temporal changes in torque producing abilities of the thigh within African soccer players. Twenty amateur Black South African soccer players performed the SAFT90 soccer match-play simulation protocol, while isokinetic measurements were obtained pre-exercise (T0), after the 1st half (T45), after half time (T60) and after the 2nd half (T105). During SAFT90 performance, significant overall concentric quadriceps peak torque changes were observed (1.05 rad · s−1 = 16.6%, 3.14 rad · s−1 = 9.5%). Eccentric hamstring peak torque also decreased significantly over time (1.05 rad · s−1 = 17.4%, 3.14 rad · s−1 = 18.5%), with significant reductions occurring during both halves. The functional strength ratio (eccH:conQ) at 3.14 rad · s−1 was observed to significantly decrease by 10.1% overall. The indicated time-dependent changes in Black South African players have implications for competitive performance and increased predisposition to hamstring muscle injuries. Because of muscle fatigue, the hamstrings may have insufficient eccentric strength during the late swing phase when sprinting, resulting in eccentric overload and damage to the muscle. The changes in strength found in the current study help explain the increased predisposition to hamstring strains during the latter stages of both halves of match-play as reported by epidemiological studies.

Acute effects of static stretching on peak and end-range hamstring-to-quadriceps functional ratios.

To evaluate if static stretching influences peak and end-range functional hamstring-to-quadriceps (H/Q) strength ratios in elite women athletes. Eleven healthy female athletes in an elite competitive level participated to the study. All the participants fulfilled the static stretching or non-stretching (control) intervention protocol in a randomized design on different days. Two static unassisted stretching exercises, one in standing and one in sitting position, were used to stretch both the hamstring and quadriceps muscles during these protocols. The total time for the static stretching was 6 ± 1 min. The isokinetic peak torque measurements for the hamstring and quadriceps muscles in eccentric and concentric modes and the calculations for the functional H/Q strength ratios at angular velocities of 60°/s and 180°/s were made before (pre) and after (post) the control or stretching intervention. The strength measurements and functional strength ratio calculations were based during the entire- and end-range of knee extension. The pre-test scores for quadriceps and hamstring peak torque and end range values were not significantly different between the groups (P > 0.05). Subsequently, although the control group did not exhibit significant changes in quadriceps and hamstring muscle strength (P > 0.05), static stretching decreased eccentric and concentric quadriceps muscle strength at both the 60°/s and 180°/s test speeds (P < 0.01). Similarly, static stretching also decreased eccentric and concentric hamstring muscle strength at both the 60°/s and 180°/s test speeds (P < 0.01). On the other hand, when the functional H/Q strength ratios were taken into consideration, the pre-intervention values were not significant different between the groups both during the entire and end range of knee extension (P > 0.05). Furthermore, the functional H/Q strength ratios exhibited no significant alterations during the entire and end ranges of knee extension both in the static stretching or the control intervention (P > 0.05). According to our results, static stretching routine does not influence functional H/Q ratio. Athletes can confidently perform static stretching during their warm-up routines.

Functional Strength Ratio in Athletes with and Without Glenohumeral Internal Rotation Deficit (GIRD)

Objectives:Eccentric external rotator (ER) and concentric internal rotator (IR) strength is expressed as a functional strength ratio (ER:IR) for shoulder. The difference in functional strength ratio has been well documented in athletes, but no one compared the functional ratio in athletes with glenohumeral internal rotation deficit (GIRD). The aim of this study was to investigate the effects of GIRD on functional ER:IR strength ratio of the adolescent athletes.Methods:Fifty-three adolescent athletes (12-18 years) from basketball and volleyball teams participated in the study. All the athletes were filled a questionnaire to obtain demographic information and information about their sporting activity. To determine the GIRD, the range of glenohumeral internal rotation motion was measured with the use of a digital inclinometer. An isokinetic dynamometer was used for the assessment of eccentric and concentric muscle strength of the dominant and non-dominant shoulders. Student-t test was used to assess the difference on ER:IR strength ratio between groups.Results:After the clinical examination of all shoulders the athletes were divided into 2 different groups, which were shoulders with glenohumeral internal rotation deficit (Group 1, n=34) and shoulders without GIRD (Group 2, n=22). There was a significant difference among groups on functional ER: IR strength ratio (t=-2.172, p=0.034). The ratio was lower in shoulders with GIRD.Conclusion:GIRD has an adverse effect on functional shoulder ratio, which is one of the causes of shoulder injuries in adolescent athletes. Therefore, GIRD should be treated to prevent future injuries.

Is it Easier to Prepare Femoral Tunnel for Anatomic ACL in Figure 4 Position?

Objectives:Eccentric external rotator (ER) and concentric internal rotator (IR) strength is expressed as a functional strength ratio (ER:IR) for shoulder. The difference in functional strength ratio has been well documented in athletes, but no one compared the functional ratio in athletes with glenohumeral internal rotation deficit (GIRD). The aim of this study was to investigate the effects of GIRD on functional ER:IR strength ratio of the adolescent athletes.Methods:20 patients who had been applied anatomical anterior cruciate ligament (ACL) reconstruction with hamstring autograft by same surgeon in 2014 were included, 10 patients in each group. The randomization was performed by beginning with the flexion technique and changing the technique in each subsequent patient according to operation order. The mean age was 28 years (22-35 years) for flexion group and 29 years (23-35) for figure four group. Operations were performed by dropping down the limb from table without leg holder. During the preparation of femoral tunnel, the limb was hyperflexed sagittally in the flexion group and was hyperflexed in figure four position in the figure four group. Patients were evaluated in terms of imagination of femoral tunnel entrance during surgery, surgery duration at the time of femoral tunnel preparation, outlet of the guidewire from the thigh and postoperative radiological image of the tunnel.Results:At figure four group, arthroscopic view of femoral tunnel inlet was found subjectively more satisfying, shorter preparation time of tunnel and outlet point of guidewire from the skin closer to posterior than other group, but did not observe peroneal nerve injury. In the measurement made by radiological assessment, there was no difference the angle of femoral tunnel with femoral anatomical axis.Conclusion:In our study, when the figure four position is used, a better arthroscopic view was obtained for femoral tunnel of ACL. While control of movements of hip joint is required to hold the knee in the appropriate position in flexion group, a flexion applied from the ankle is sufficient in figure four position. As the knee height from the ground changes when the knee flexed over 120° sagittally, the operation table height should be set according to surgeon’s length. We found that this process extends the surgery duration. The outlet of guidewire from skin was more posterior in figure four group compared to flexion group. Because of the root of peroneal nerve, this was identified as disadvantage. Although there are some limitations, the findings support our hypothesis: during the femoral tunnel preparation, the surgeon’s job is facilitated by figure four position of the knee.

Profiling the isokinetic shoulder rotator muscle strength in 13- to 36-year-old male and female handball players

ObjectivesTo evaluate the external (ER) and internal rotator (IR) muscles' isokinetic peak torque and conventional and functional strength ratios in handball players and controls of different ages. DesignCross-sectional and descriptive analysis. SettingExercise Physiology Laboratory. ParticipantsA total of 228 participants (108 athletes and 120 controls) were divided into five groups according to age, ranging from 13 to 36 years old. Main outcome measuresIsokinetic tests were performed concentrically at 60 and 300 deg s−1 and eccentrically at 300 deg s−1. ResultsThe differences between the athletes and controls regarding the peak torque of the ER and IR muscles were significant in males older than 18 years. The peak torque of the IR and ER muscles increased significantly across age in male athletes, but not in female athletes, except in the case of ER peak torque, which differed significantly between 13 and 16 years old. The female athletes presented higher conventional ratios (0.81 ± 0.07) than males (0.66 ± 0.08). Values represent means and standard deviations. Athletes and controls showed mean functional strength ratios below 1.0. ConclusionsAlthough there were no muscular ratio differences between the athletes and the controls, their ratio values were below the literature-recommended reference values to prevent shoulder injuries.

Isokinetic Testing of Evertor and Invertor Muscles in Patients With Chronic Ankle Instability

Ankle sprains are among the most common sport-related injuries and can lead to chronic ankle instability. Impaired sensorimotor function of the ankle musculature is often suggested as a cause. The current study sought to assess and compare the isokinetic performance and electromyographic patterns of evertor and invertor muscles in patients with chronic ankle instability and in a control group. Twelve patients with chronic ankle instability and twelve healthy subjects were included. Isokinetic eccentric and concentric testing at various angular velocities was performed for eversion and inversion movements. The corresponding myoelectric activities of the fibularis longus and tibialis anterior muscles were quantified from surface electromyographic recordings by computing average root mean square values. Patients had lower myoelectric activity of the evertor and invertor muscles than controls did; this difference could account for the eccentric weakness associated with ankle instability. Functional strength ratios revealed a dynamic strength imbalance in unstable ankle patients and that may contribute to recurrent injury. Our findings suggest that rehabilitation programs for unstable ankle patients must be focused on the motor control of eccentric contractions of the ankle evertors and invertors, to boost these muscles' contribution to ankle stabilization.

Fiabilidad absoluta de los índices convencional y funcional y momento máximo de fuerza isocinética de la flexión y extensión de rodilla

IntroductionIsokinetic strength tests are probably the most common measurement tools for estimating muscle function in sport setting. However, there is little scientific evidence justifying their use as accurate tools. For that reason, the main purpose of this study was to examine the absolute reliability of isokinetic functional and conventional strength ratios as well as concentric and eccentric isokinetic knee flexion and extension peak torque (PT) of the knee in recreational active young adults. Material and methodsFifty two participants performed 3 measurement sessions to record the functional and conventional strength ratios and concentric and eccentric knee flexion and extension PTs with a 72-96hours rest interval between consecutive sessions. The inter-session absolute reliability was measured through change in the mean between measures (expressed as percentage value [CM]), typical percentage error (% within-subjects variation [CVTE]), and intraclass correlations (ICC). ResultsPoor absolute reliability scores were found for conventional (CM=0.2%-0.4%; CVTE=16%-18%; ICC=0.6-0.7) and functional (CM=−2.1%-0.2%; CVTE=18%-20%; ICC=0.3-0.7) knee strength ratios. Likewise, moderate absolute reliability scores were observed for PT values independently of the knee movement (flexion and extension), type of muscle contraction (concentric and eccentric) and angular velocity (60°/s and 180°/s). ConclusionsAn observed change greater than ≈ 12% and ≈ 17% for PT scores (independently of knee movement and muscle contraction) and isokinetic ratios (conventional and functional), respectively, from baseline scores would suggest that a real change in strength balance was likely and not because a measurement error. These absolute reliability scores could be sensitive enough to detect large changes, as showed after completing rehabilitation programs for subjects injured.

Profile of isokinetic eccentric-to-concentric strength ratios of shoulder rotator muscles in elite female team handball players

The purpose of this study was to establish the isokinetic profile of shoulder rotator muscles strength in female handball players. Twenty-seven handball players performed concentric and eccentric strength tests of both dominant and non-dominant upper limbs on an isokinetic dynamometer. Internal and external rotator muscles peak torque was assessed at 1.05, 3.14, and 5.23 rad · s−1 in concentric mode and at 3.14 and 5.23 rad · s−1 in eccentric mode. Concentric balance ratio and functional ratio were obtained. Bi-lateral deficiency was compared. Concentric strength for internal and external rotation was significantly greater for the dominant than for the non-dominant limb for all speeds (P ≤ 0.0001). For eccentric actions, internal rotator muscles were stronger in the dominant than the non-dominant limb (P ≤ 0.0001) at both speeds. Concentric balance and functional balance ratios did not differ between sides at 3.14 rad · s−1 (P = 0.1631), but at 5.23 rad · s−1 the functional balance ratio in the dominant limb was lower than for the non-dominant limb (P = 0.0500). Although the dominant side was stronger than the non-dominant side, balance concentric ratios remained the same, with only the functional strength ratio different at 5.23 rad · s−1. Our results suggest that concentric strength exercises be used for internal and external rotators on the non-dominant side, and functional exercise that improves eccentric rotation strength for prevention programmes.

Functional Isokinetic Strength Ratios in Baseball Players With Injured Elbows

Elbow injuries are widely reported among baseball players. The elbow is susceptible to injury when elbow-flexor and -extensor forces are imbalanced during pitching or throwing. Assessment of muscle-strength ratios may prove useful for diagnosing elbow injury. The purpose of this study was to assess the relationship between the elbow-flexor and -extensor functional isokinetic ratios and elbow injury in baseball players. Retrospective study. Biomechanics laboratory. College baseball players with (n = 9) and without (n = 12) self-reported elbow pain or loss of strength were recruited. Trials were conducted using a dynamometer to assess dominant-arm flexor and extensor concentric and eccentric strength at angular velocities of 60 degrees and 240 degrees/s. Functional isokinetic ratios were calculated and compared between groups. Regression analysis revealed that a ratio of biceps concentric to triceps concentric strength greater than 0.76 (the median value) significantly predicted elbow injury (P = .01, odds ratio of injury = 24). No other ratios or variables (including position played) were predictive of injury status. These findings suggest that the ratio of biceps concentric to triceps concentric functional strength strongly predicts elbow-injury status in baseball players. Assessment of this ratio may prove useful in a practical setting for training purposes and both injury diagnosis and rehabilitation.

The effects of multidirectional soccer-specific fatigue on markers of hamstring injury risk

The purpose of this work was to investigate the effect of multidirectional soccer-specific fatigue on hamstring muscle strength and angle of peak torque. Sixteen male semi-professional soccer players (mean ± S.D.: age: 21.3 ± 2.9 years; height 185.0 ± 8.7 cm; body mass 81.6 ± 6.7 kg) completed the SAFT 90, a multidirectional, intermittent 90-min exercise protocol based on data from English Championship soccer matches. Prior to exercise ( t 0), at half-time ( t 45) and post-exercise ( t 105), subjects performed three maximal dominant limb isokinetic contractions (Biodex, System 3) at 120° s −1 through a 90° range for concentric and eccentric knee flexors and concentric knee extensors. Analysis of variance revealed significant time dependant reductions in gravity corrected eccentric hamstring peak torque, and consequently in the functional hamstring:quadriceps ratio ( P < 0.01). Eccentric hamstring peak torque decreased significantly during each half ( t 0: 272.0 ± 43.2; t 45: 240.4 ± 43.3; t 105: 226.3 ± 45.7 N m). The functional hamstring:quadriceps ratio also decreased significantly during each half ( t 0: 116.6 ± 21.2; t 45: 107.1 ± 17.6; t 105: 98.8 ± 20.3%). There were no significant changes in concentric hamstring or quadriceps peak torque observed during SAFT 90 ( P > 0.05). Data analysis also revealed significant differences for Angle of Peak Torque for eccentric hamstrings ( P < 0.05) which was significantly higher at the end of each half ( t 45: 37 ± 15; t 105: 38 ± 18°) than the pre-exercise value ( t 0: 28 ± 12°). There was a time dependant decrease in peak eccentric hamstring torque and in the functional strength ratio which may have implications for the increased predisposition to hamstring strain injury during the latter stages of match-play.