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Purpose: To compare the development of fatigability during a moderate-intensity cycling exercise between women with fibromyalgia (FM) and control women (CON) after acute ingestion of caffeine and placebo. Methods: Ten FM and 10 CON women performed a 30-min moderate-intensity cycling exercise 1 h after the ingestion of a capsule containing either caffeine or a placebo. Fatigability and its central and peripheral determinants were determined via changes from pre- to post-15 and post-30 min of exercise in maximal voluntary isometric contractions, voluntary activation (VA), and quadriceps potentiated twitch torque (Qtw-pot), respectively. Heart rate, muscle oxygen saturation, perceptive responses, mood state, localized and widespread pain, and sleepiness were also monitored during and after exercise. Results: There was a time versus group interaction for maximal voluntary isometric contraction and VA (P < 0.001) but not for Qtw-pot (P = 0.363), indicating a greater rate of fatigability development, mainly caused by central mechanisms, in the FM than in the CON group. There was also a main effect of condition for VA (P = 0.011), indicating that caffeine attenuates central mechanisms of fatigability in both groups. Caffeine ingestion also increased muscle oxygenation, perceived vigor, and energy, and decreased leg muscle pain, sleepiness, and perceived fatigue in both groups. However, caffeine improved perceived pleasure/displeasure and exercise adherence likelihood only in the FM group. Conclusions: Compared with CON, women with FM present a greater rate of fatigability during exercise, mainly of central origin. Caffeine seems to be a promising bioactive to counteract the central mechanisms of fatigability and improve the exercise experience among FM women. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the immediate effect of Dynamic TapeTM (DT) on hip muscle activation and torque and on lower limb kinematics. Forty-five healthy, recreationally active women were randomly assigned to three groups: 1) submitted to the application of DT in the active form in the gluteus medius (GMed) muscle (BG; n = 15), 2) submitted to the application of DT in the placebo form in the GMed muscle (PG; n = 15), and 3) not submitted to any intervention (CG; n = 15). Participants were evaluated for GMed and gluteus maximus (GMax) muscle activation in a maximal voluntary isometric contraction, simultaneously with the assessment of the hip abductor and extensor torques, as well as during two functional tasks – single leg squat (SLS) and jump landing + maximum vertical jump (VJ) – simultaneously with a 2-D kinematic assessment of the lower limb. After DT application in BG, there was a significant decrease in the hip abductor time to peak torque (P = 0.004), hip extensor torque (P = 0.02), excursion to hip adduction (P = 0.007), and to knee flexion (P = 0.02) during the SLS, as well as in GMed activation during VJ (P < 0.05). DT was able to reduce GMed activation and modify lower limb torque and kinematics. [ABSTRACT FROM AUTHOR]

The aims of the present study were to: i) analyse the between-session reliability of dry-land and in-water swimming tests, and ii) investigate the prevalence of meaningful asymmetries in swimming athletes. Twenty-eight swimmers (21 males, 7 females) performed anthropometric, shoulder range of motion (ROM), countermovement jump, shoulder isokinetic torque, and 15-s tethered swimming tests two times, 1 week apart. Inter-limb asymmetries were calculated for each variable. Raw data reliability was determined using the intraclass coefficient correlation (ICC) and the typical error of measurement (TEM), and effect size (ES) was used to determine systematic bias between test sessions. At an individual level, inter-limb asymmetries were compared to the coefficient of variation (CV) to determine whether they were real. The between-session reliability was good to excellent (0.75 to 1.00) for most of the raw data, except for ROM. Between-session ES was predominately "trivial" or "small" for raw data and asymmetries, reinforcing that the values did not change significantly between the sessions. In addition, real asymmetries were seen in some tested metrics, depending on the test. In conclusion, the tested variables presented good levels of between-session reliability and were able to detect real and consistent asymmetries. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to compare three-dimensional kinematic of the trunk, pelvis, hip, and knee during the single-leg squat and hip torque in individuals with and without isolated patellofemoral osteoarthritis (PFOA). Patients and methods: This cross-sectional study evaluated trunk, pelvis, hip, and knee kinematics at 30°, 45°, and 60° knee flexion during the single-leg squat using the Vicon motion capture and analysis system, the Nexus System 2.1.1, and 3D Motion Monitor software. Sixteen individuals (8 males, 8 females; mean age: 49.3±6.2 years; range 40 to 61 years) participated in the study, of which eight were PFOA patients and eight were healthy controls. Isometric hip abductor, extensor, and external rotator torques were evaluated using a handheld dynamometer. Results: The PFOA group exhibited greater hip adduction at 30° (p=0.008), 45° (p=0.005), and 60° (p=0.008) knee flexion in the descending phase of the single-leg squat, as well as at 60° (p=0.009) and 45° (p=0.03) knee flexion in the ascending phase. No significant differences were found between groups for other kinematic variables (p>0.05). The PFOA group exhibited lower isometric hip abductor (p=0.02), extensor (p<0.001), and external rotator (p=0.007) torques. Conclusion: Individuals with PFOA exhibited excessive hip adduction that could increase stress on the lateral patellofemoral joint at 30°, 45°, and 60° knee flexion during the single-leg squat and exhibited weakness of the hip abductors, extensors, and external rotators in comparison to healthy controls. [ABSTRACT FROM AUTHOR]

The objective was to investigate the association between rate of torque development (RTD) and torque steadiness (TS) of the lower limb and the occurrence of prospective falls in community-dwelling older adults without falls in the previous year. One hundred older adults performed the tests to obtain the RTD and TS of the hip, knee, and ankle. New episodes of falls were monitored through telephone contact for a prospective period of 12 months. The association of RTD and TS with the occurrence of prospective falls was verified by multiple logistic regression adjusted for confounding variables. There was no association between RTD of hip, knee, and ankle and prospective falls. Only the TS at 50% of the peak torque of the hip flexors was associated with the occurrence of future falls (p = .023). Identifying modifiable risk factors for the first fall in older adults is essential for the development of adequate prevention programs. [ABSTRACT FROM AUTHOR]

This study investigated additional and traditional variables from isokinetic test of thigh muscles in soccer players across different field positions. One hundred and eighty-nine athletes performed maximal concentric isokinetic knee contractions on dominant (DL) and non-dominant limb (NDL) at 60º/s and 240º/s. The additional outcomes peak torque angle (AngPT), acceleration time (AcT) and time to peak torque (TPT) and traditional outcomes Peak torque (PT), total work (TW) and power (Pw) were extracted from the exam. Goalkeepers (GK), side backs (SB), central backs (CB), central defender midfielders (CDM), central attacking midfielders (CAM) and forwards (FW) were considered. Comparisons between limbs and positions demonstrated that SB extensors of the DL presented TPT lower (p = 0.006) and AngPT higher (p = 0.011) than NDL at 60°/s. CDM extensors of the DL showed lower TPT at 60°/s (p = 0.003) and 240°/s (p = 0.024). CAM flexors of the DL showed lower TPT (p = 0.026) and AcT (p = 0.021) at 240°/s than NDL. CB, CDM and CAM extensors of the NDL showed higher PT, TW and Pw than DL (p < 0.05). In conclusion, there are muscle imbalances between limbs in SB, CDM and CAM and across different field positions. [ABSTRACT FROM AUTHOR]

Purpose: In postmenopausal women, optimizing muscular strength and physical performance through proper resistance training (RT) is crucial in achieving optimal functional reserve later in life. This study aimed to compare if a higher-load-tolower-load (HL-to-LL) scheme is more effective than a lower-load-to-higher-load (LL-to-HL) scheme on muscular strength and physical performance in postmenopausal women after 12 and 24 wk of RT. Methods: Twenty-four postmenopausal women were randomized into two groups: LL-to-HL (n = 12, 27-31 repetitions maximum (RM) in the first 12 wk, and 8-12RM in the last 12 wk) or HL-to-LL (n = 12, 8-12RM during the first 12 wk, and 27-31RM in the last 12 wk). Muscular dynamic (1RM test) and isometric strength (MIVC) and functional tests (sit-to-stand power, 400-m walking, and 6-min walking) were analyzed at baseline, after 12 and 24 wk. Results: Different load intensity transition schemes resulted in enhancements (P < 0.05) in dynamic (45° leg press: LL-to-HL = 21.98% vs HL-to-LL = 16.07%; leg extension: LL-to-HL = 23.25% vs HL-to-LL = 16.28%; leg curl: LL-to-HL = 23.89% vs HL-to-LL = 13.34%) and isometric strength (LLto-HL = 14.63% vs HL-to-LL = 19.42%), sit-to-stand power (LL-to-HL = 7.32% vs HL-to-LL = 0%), and walking speed (400-m test: LL-to-HL = 3.30%vsHL-to-LL = 5.52%; 6-min test: LL-to-HL = 4.44%vs HL-to-LL = 5.55%) after 24wk of RT, without differences between groups (P > 0.05). However, only the HL increased the dynamic strength in 45° leg press and leg extension and sit-to-stand power. Moreover, walking speed changes were more strongly correlated with the changes in MIVC (P < 0.05). Conclusions: Our results indicate that both load intensity transition schemes produce similar improvements in muscular strength and physical performance in postmenopausal women after 24 wk of RT. However, the HL was more effective in increasing 45° leg press and leg extension strength, as well as power (mainly when performed after the LL), whereas having little effect on leg curl strength, isometric strength, and walking speed. Our findings suggest that although an HL makes a muscle isotonically stronger, it may have limited impact on isometric strength and walking speed in postmenopausal women. [ABSTRACT FROM AUTHOR]

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This study investigated the effect of 1-week oral administration of propolis on muscle fatigue and recovery after performing a fatigue task (total 100 maximal voluntary concentric knee extension repetitions). In this placebo-controlled, double-blind study, 18 young men consumed a formulation with high Brazilian green propolis dose (H-BGP), a formulation with low Brazilian green propolis dose, or a placebo, for 1 week before performing the fatigue task (an interval between each intervention: 1–2 weeks). Maximal voluntary contraction torque, central fatigue (voluntary activation and root mean square values of the surface electromyography amplitude), and peripheral fatigue (potentiated triplet torque) were assessed before, immediately after, and 2 minutes after the fatigue task. Maximal voluntary contraction torque decreased immediately after the fatigue task in all conditions (P<0.001); however, it recovered from immediately after to 2 minutes after the fatigue task only in the H-BGP condition (P<0.001). Furthermore, there was a significant decrease in voluntary activation (P<0.001) and root mean square values of the surface electromyography amplitude (P≤0.035) only in the placebo condition. No significant difference was observed in the time-course change in potentiated triplet torque between the conditions. These results suggest that oral administration of propolis promotes muscle fatigue recovery by reducing central fatigue. [ABSTRACT FROM AUTHOR]

Background The single leg bridge test (SLBT) has been introduced in the sports context as a way of estimating hamstring muscle capacity for prevention and rehabilitation of hamstring strain injuries. Purpose The primary aim was to examine the association between SLBT scores with concentric and eccentric knee flexor peak torques. Secondarily, this study aimed examine the association of between-limb asymmetries provided by SLBT and isokinetic tests. Study design Cross-sectional study. Methods One hundred male soccer players (20±3 years) performed the SLBT and the knee flexion-extension isokinetic dynamometry evaluation (60°/s) billaterally during a single visit. SLBT score (i.e., number of repetitions until failure) and concentric and eccentric knee flexor peak torques (normalized per body mass) were considered for analysis. For both SLBT and isokinetic dynamometry, between-limb asymmetry was calculated as the percentage difference between the left limb and the right limb. Associations were assessed through Pearson's correlation coefficient. Results The mean SLBT score was 33.6±9.6 repetitions, concentric peak torque was 2.00±0.22 Nm/kg, and eccentric peak torque was 2.79±0.44 Nm/kg. Between-limb asymmetry was 0.4±9.6%, 1.08±8.5%, and 1.64±14.61% in SLBT, concentric, and eccentric tests, respectively. There was a poor association of SLBT score with concentric (p<0.001, r=0.275) and eccentric (p=0.002, r=0.215) peak torques. The SLBT between-limb asymmetry was poorly associated with asymmetry found in concentric peak torque asymmetry (p=0.033, r=0.213) and was not associated with eccentric peak torque asymmetry (p=0.539, r=0.062). Conclusion The SLBT should not be used as a clinical tool to assess the maximum strength of hamstring muscles. [ABSTRACT FROM AUTHOR]

BACKGROUND: Imbalance between flexor and extensor muscles of the trunk could negatively influence spinal stability. OBJECTIVES: Investigate the strength balance between flexor and extensor muscles of the trunk in military firefighters with non-specific chronic low back pain (NSCLBP). METHODS: One hundred and two male firefighters were assessed in an isokinetic dynamometer at 120°/s and 60°/s to investigate the balance ratio between flexor and extensor (F/E) muscles. RESULTS: An F/E ratio of 0.72 (SD: 0.22; 95% CI: 0.67–0.76; SEM: 0.02) was observed at 60°/s and 0.94 (SD: 0.41; 95% CI: 0.85–1.03; SEM: 0.04) at 120°/s. The mean peak torque of the extensor muscles was 343.1 N.m/Kg (SD: 94.87; 95% CI: 322.8–363.5; SEM: 10.23) at 60°/s and 270.5 N.m/Kg (SD: 113; 95% CI 246.3–294.8; SEM: 12.18) at 120°/s. The mean peak torque of the flexor muscles was 232.4 N.m/Kg (SD: 53.86; 95% CI 220.8–243.9; SEM: 5.81) at 60°/s and 223.8 N.m/Kg (SD: 66.34; 95% CI 209.6–238.1; SEM: 7.15) at 120°/s. All torques generated by the extensor muscles were higher than the flexor muscles (p < 0.05). CONCLUSIONS: Firefighters with NSCLBP presented a normal F/E balance ratio and higher strength of extensor muscles of the trunk. [ABSTRACT FROM AUTHOR]

Context: Imbalance in shoulder-rotator muscles has been considered a risk factor for injuries in handball. Strength training programs (STPs) may play an important preventive role. Objective: To verify the effects of an STP using elastic bands on shoulder muscles and ball-throwing speed. Design: Randomized and prospective controlled trial. Setting: Exercise physiology laboratory. Participants: Thirty-nine female handball players were randomly assigned to an experimental (EG, n = 21, 15.3 ± 1.1 y) or a control (CG, n = 18, 15.0 ± 0.8 y) group. Intervention: The EG performed the STP with elastic-band progressive exercises for 6 wk before regular handball training, and the CG underwent only their regular training. Main Outcome Measures: Before and after the STP, both groups underwent a ball-throwing-speed test and isokinetic test to assess shoulder internal- (IR) and external-rotator muscle performance. Results: Average power values for IR muscles presented a significant group-vs-time interaction effect (F = 3.9, P = .05); EG presented significantly higher values after the STP (P = .03). Ball speed presented higher values in EG after the STP in standing (P = .04) and jumping (P = .03) throws. IR peak-torque values and balance in shoulder-rotator muscles presented no group-vs-time interaction effect. Conclusions: STP using elastic bands performed for 6 wk was effective to improve muscle power and ball speed for young female handball players. [ABSTRACT FROM AUTHOR]

Purpose: To analyze the relationship between the responses of isometric peak torque (IPT) and maximal rate of force development (RFDmax) with the changes in stroking parameters in an exhaustive exercise performed in front crawl. Methods: Fifteen male swimmers performed, on different days, the following protocols: maximal 400-m trial, strength tests before and after an exhaustive test at 100% of the mean speed obtained during the 400-m test, and the same procedures on day 2. Results: The IPT of elbow flexors (79.9 ± 19.4 and 66.7 ± 20.0 N⋅m) and elbow extensors (95.1 ± 28.0 N-m and 85.8 ± 30.5 N⋅m) was decreased after the swim test, as was RFDmax (521.8 ± 198.6 and 426.0 ± 229.9 N-m/s; 420.6 ± 168.2 and 384.0 ± 143.5 N⋅m/s, respectively). Stroke length decreased during the swim test (1.96 ± 0.22 and 1.68 ± 0.29 m/stroke), while stroke rate increased (37.2 ±3.14 and 41.3 ± 4.32 strokes/min). The propulsive phases increased while the nonpropulsive phases decreased during the test. Significant correlation was found between the changes in IPT and stroke length, stroke rate and recovery (elbow flexors), and entry and catch phase (elbow extensors). In addition, significant correlation was found between the changes in RFDmax of elbow flexors with the changes in pull and recovery phases. Conclusion: Changes in swim technique during an exhaustive test can be, at least in part, associated with fatigue of the arm muscles. [ABSTRACT FROM AUTHOR]

Background Studies 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. Purpose To 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 design Cross-sectional study. Methods A 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. Results There 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). Conclusions CR 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. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate and compare the hamstring (H) and quadriceps (Q) strength, bilateral difference and balance ratios in female soccer players. Ninety-three athletes from three age groups: under 13 (U13), 15 (U15) and 18 (U18) participated in the study performing isokinetic tests to measure peak torque, total work, average power and torque at 30º of thigh muscles. Conventional strength balance ratios, angle-specific balance ratio and bilateral strength difference were evaluated. There was bilateral strength difference for extensor muscles total work (p = 0.02) in U13 and flexor muscles peak torque (p = 0.02) in U15. All variables were superior in U15 than U13 (p <.05). There was no strength difference between U15 and U18. Balance ratios did not differ between sides or age groups. The study showed that although peak torque values were higher in U15 than in U13, balance ratios were similar. [ABSTRACT FROM AUTHOR]

The aim was to evaluate primary implant stability and bone microarchitecture in two drilling situations, by comparing the conventional technique (CT) and osseodensification (OD) (Versah Burs - Jackson - Mississippi - USA). The implant insertion torque (IT), implant stability quotient (ISQ), and the peri-implant trabecular microstructure were assessed on bone fragments obtained from pig's tibia (n=12), divided between CT (n=6) and OD (n=6). After the drilling procedure, the implants were installed (3.5x8.5 mm, Epikut - SIN - São Paulo - Brazil). The IT and ISQ were measured using a digital torque wrench and resonance frequency analysis. Then, the bone fragments containing the implants were removed with a trephine and analyzed by Microtomography (µCT, 8.0 µm). The comparison between groups was performed using the unpaired t-test (α=0.05). The results revealed that OD promotes a higher insertion torque (CT: 7.67±2.44 Ncm; OD: 19.78±5.26 Ncm) (p=0.0005), although ISQ was not different (CT: 61.33±4.66; OD: 63.25±4.58) (p=0.48). There was a significant increase in peri-implant bone volume (CT: 23.17±3.39 mm3; OD: 32.01±5.75 mm3) (p=0.008), and trabecular parameters: separation (CT: 0.4357±0.03 mm; OD: 0.3865±0.04 mm) (p=0.0449), number (CT: 1.626±0.18 1/mm; OD: 1.946±0.13 1/mm) (p=0.007), and thickness (CT: 0.1130±0.009 mm; OD: 0.1328±0.015 mm) (p=0.02). Structure model index (SMI) data demonstrate no significant differences between groups (CT: 1.7±0.2; OD: 1.4±0.4) (p=0.12). In conclusion, OD increases the insertion torque values and promotes beneficial changes regarding bone microarchitecture compared with CT, revealing more peri-implant bone volume with consequent higher primary stability.

This study compared the differences in neural and muscular mechanisms related to explosive torque in chronically strength‐trained young and older men (>5 years). Fifty‐four participants were allocated into four groups according to age and strength training level: older untrained (n = 14; 65.6 ± 2.9 years), older trained (n = 12; 63.6 ± 3.8 years), young untrained (n = 14; 26.2 ± 3.7 years), and young trained (n = 14; 26.7 ± 3.4 years). Knee extension isometric voluntary explosive torque (absolute and normalized as a percentage of maximal voluntary torque) was assessed at the beginning of the contraction (ie, 50, 100, and 150 ms—T50, T100, and T150, respectively), and surface electromyogram (sEMG) amplitude (normalized as a percentage of sEMG recorded during maximal voluntary isometric contraction) at 0‐50, 50‐100, and 100‐150 time windows. Supramaximal electrically evoked T50 was assessed with octet trains delivered to the femoral nerve (8 pulses at 300 Hz). Voluntary T50, T100, and T150 were higher for trained than untrained in absolute (P < 0.001) and normalized (P < 0.030) terms, accompanied by higher sEMG at 0‐50, 50‐100, and 100‐150 ms (P < 0.001), and voluntary T50/octet T50 ratio for trained. Greater octet T50 was observed for the young trained (P < 0.001) but not for the older trained (P = 0.273) compared to their untrained counterparts. Age effect was observed for voluntary T50, T100, and T150 (P < 0.050), but normalization removed these differences (P > 0.417). Chronically strength‐trained young and older men presented a greater explosive torque than their untrained pairs. In young trained, the greater explosive performance was attributed to enhanced muscular and neural mechanisms, while in older trained to neural mechanisms only. [ABSTRACT FROM AUTHOR]

• Hip/knee flexion was associated with runners anterior reach distance in the modified star excursion balance test. • Hip flexion was associated with the posteromedial and knee flexion with the posterolateral reach. • Hip extensor strength was associated with posteromedial, posterolateral and composite reaches. • Trunk kinematics and strength were not associated with runners' performance in this test. Reduced trunk and lower limb movement and hip and trunk muscles weakness may compromise the athletes' performance on the modified Star Excursion Balance Test (mSEBT). To investigate the relationship of trunk and lower limb kinematics and strength with the performance on the mSEBT of runners at high risk of injury. Thirty-nine runners performed the mSEBT with the dominant limb as the support limb. An Inertial System was used to capture the trunk, hip, knee and ankle movement during the mSEBT. A handheld dynamometer was used to measure the strength of trunk extensors and lateral flexors muscles, and hip extensors, lateral rotators and abductors of the support limb. Multiple regressions were used to investigate if trunk and lower limbs kinematics and trunk and hip muscles strength are associated with performance during the mSEBT. Reduced hip flexion and greater knee flexion range of motion (ROM) were associated with anterior reach in the mSEBT (r2 = 0.45; p <.001), greater hip flexion ROM was associated with posteromedial reach (r2 = 0.15; p =.012) and greater knee flexion ROM was associated with posterolateral reach (r2 = 0.23; p <.001). Hip extensor strength was associated with posteromedial (r2 = 0.14; p =.017), posterolateral (r2 = 0.10; p =.038) and composite reaches (r2 = 0.16; p =.009). Hip and knee kinematics in the sagittal plane explained 15–45% of the runners' performance on the mSEBT and hip extensor strength explained 10–16% of the mSEBT performance. These findings provide useful information on the contribution of joints kinematics and strength when evaluating dynamic postural control in runners at high risk of injury. [ABSTRACT FROM AUTHOR]

Background: Anklebot therapy has proven to be effective in improving hemiparetic gait. However, neither ankle torque steadiness nor the relationship between changes in force control and functional tasks after therapy with Anklebot were described. Objective: To assess whether a single session of robotic therapy promotes short-term ankle adaptations that influence ankle torque steadiness and walking speed in individuals with chronic hemiparesis. Methods: A sample of participants who had residual hemiparesis deficits (hemiparesis group; n = 13) and age- and sex-matched healthy control participants (control group; n = 13). For sample characterization, balance, mobility, sensorimotor impairment, and daily living activities performance were measured. Results: Differences in functional tests were identified only when the control and hemiparesis groups (F = 29.1; p =.001) were compared during the 10-metre Walking Test. Regarding the pre- and post-robotic assistance session, no significant difference was observed for any comparison (p >.05), except for the steadiness test, as demonstrated by the standard deviation (F = 7.10; p =.01) and coefficient of variation (F = 6.20; p =.02). The hemiparesis group showed better torque steadiness during dorsiflexion post-robotic assistance therapy (p ≥ 0.02) when compared with pre-robotic assessment. Correlations were identified between steadiness and walking speed variables. Conclusion: People with chronic hemiparesis presented short-term performance gains in torque steadiness, especially during dorsiflexion, after a single robotic therapy session. The robotic therapy did not influence the walking speed, although low to moderate correlations between torque steadiness variables and walking speed were observed. [ABSTRACT FROM AUTHOR]

Context: Recently, attention in sports has been given to eccentric hip-muscle function, both in preventing musculoskeletal injuries and improving performance. Objective: To determine the key isokinetic variables of eccentric hip torque that predict the functional performance of women in the single-leg triple long jump (TLJ) and the timed 6-m single-leg hop (TH). Design: Within-subject correlational study. Setting: Musculoskeletal laboratory. Participants: 32 healthy women age 18-25 y. Intervention: The participants performed 2 sets of 5 eccentric hip-abductor/adductor and lateral/medial-rotator isokinetic contractions (30°/s) and 3 attempts in the TLJ and TH. Main Outcome Measurements: The independent variables were the eccentric hip-abductor and -adductor and medial- and lateral-rotator isokinetic peak torque, normalized according to body mass (Nm/kg). The dependent variables were the longest distance achieved in the TLJ normalized according to body height and the shortest time spent during the execution of the TH. Results: The forward-stepwise-regression analysis showed that the combination of the eccentric hip lateral-rotator and -abductor isokinetic peak torque provided the most efficient estimate of both functional tests, explaining 65% of the TLJ variance (P < .001) and 55% of the TH variance (P < .001). Conclusions: Higher values for eccentric hip lateral-rotator and hip-abductor torques reflected better performance. Thus, the eccentric action of these muscles should be considered in the development of physical training programs that aim to increase functional performance. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate the effect of retightening and mechanical cycling on the maintenance of preload in the retention screws of implant-supported crowns. Materials and Methods: Five groups (n = 12 in each group) of implant-crown assemblies were created according to different abutments and veneering materials: Gold UCLA abutments cast in gold alloy veneered with ceramic (group 1) and light-curing resin (group 2), UCLA abutments cast in titanium veneered with ceramic (group 3) and light-curing resin (group 4), and zirconia abutments with ceramic veneering (group 5). The crowns were attached to implants by gold retention screws. The assemblies were submitted to mechanical cycling for a total of 1 million cycles. Removal torque measurements were performed initially and after each period of 100,000 cycles; this was followed by screw retightening with 35 Ncm of torque. Data were evaluated with analysis of variance, the paired t test, and the Student t test. Results: All groups exhibited reduced removal torque values in comparison to insertion torque initially and after all periods of mechanical cycling. Analysis of variance revealed statistically significant differences among the groups, but there were no differences among the periods of mechanical cycling or for the interaction between groups and cycling. Group 1 was the only group that did not show a difference between removal torque values of different cycling periods. The Student t test did not reveal statistically significant differencesbetween mean removal torque values obtained before and after mechanical cycling, except for group 4. Conclusions: Torque maintenance allowed screw joint stability in the present study. Mechanical cycling associated with the retightening of abutment screws did not influence the maintenance of insertion torque. [ABSTRACT FROM AUTHOR]

Background: Knee extensor strength assessment has been especially emphasized in older people, but lack of reference values limits its usefulness in geriatric evaluation. Aims: The aim of this study was to develop a reference equation for knee extensor isokinetic strength standards in older women. Methods: Knee extensor isokinetic tests at 60°/s were performed in 390 Brazilian older women aged 60–84 years (67.38 ± 5.56 years) and in a separate validation sample of 110 women (67.94 ± 6.13 years). A regression equation for peak torque (PT) was derived and compared to commonly used formulas: the equations of Neder and Gross. Age, weight and height were the only significant predictors (multiple R = 0.55; R2 = 0.30; p < 0.001). The proposed equation was examined in the independent sample. Percent from predicted values was calculated and Bland–Altman plots were constructed. Results: Both the Neder and Gross equations significantly underestimated predicted PT values (both p < 0.001); mean bias were 6.79 and 6.75, respectively. The proposed equation [PT = 39.72 − (1.24 × age) + (0.44 × weight) + (69.70 × height)] was matched with the independent sample, with a percent predicted isokinetic strength of approximately 95%, a mean bias approximately 40% lower 4.23 than the other equations, and stable across all age groups. Conclusions: Available equations for knee extensor isokinetic strength are not adequate for older women. The equation developed in the present study provided considerably lower average error and thus with more suitable reference values. [ABSTRACT FROM AUTHOR]

Background: Based on the premise that spasticity might affect gait post-stroke, cryotherapy is among the techniques used to temporarily reduce spasticity in neurological patients. This effective technique would enhance muscle performance, and ultimately, functional training, such as walking. However, understanding whether a decrease in spasticity level, if any, would lead to improving muscle performance and gait parameters is not based on evidence and needs to be clarified. Objectives: to investigate the immediate effects of cryotherapy, applied to spastic plantarflexor muscles of subjects post-stroke, on tonus level, torque generation capacity of plantarflexors and dorsiflexors, and angular/spatiotemporal gait parameters. Methods: Sixteen chronic hemiparetic subjects participated in this randomized controlled crossover study. Cryotherapy (ice pack) or Control (room temperature sand pack) were applied to the calf muscles of the paretic limb. The measurements taken (before and immediately after intervention) were: 1) Tonus according to the Modified Ashworth Scale; 2) Torque assessments were performed using an isokinetic dynamometer; and 3) Spatiotemporal and angular kinematics of the hip, knee, and ankle (flexion/extension), obtained using a tridimensional movement analysis system (Qualisys). Results: Cryotherapy decreased plantarflexor tonus but did not change muscle torque generation capacity and did not affect spatiotemporal or angular parameters during gait compared to control application. These findings contribute to the evidence-based approach to clinical rehabilitation post-stroke. Conclusions: The findings of this study suggest that cryotherapy applied to the calf muscles of subjects with chronic hemiparesis reduces muscle hypertonia but does not improve dorsiflexors and plantarflexors performance and gait parameters. [ABSTRACT FROM AUTHOR]

Isokinetic hamstring-to-quadriceps (H:Q) ratios are frequently used to assess knee muscle strength imbalances and risk of injuries/re-injuries. The use of peak torque (PT) or total work (TW) to estimate joint stability may lead to different results because of the differences between these two neuromuscular variables. Thus, the current study aimed to compare the conventional and functional H:Q ratios calculated by PT and TW. Ninety-three male professional soccer players from Brazilian first division teams performed isokinetic concentric and eccentric contractions of the quadriceps and the hamstrings at 60°/s. Muscle strength balance was calculated using the conventional torque ratio (CTR) and conventional work ratio (CWR), functional torque ratio (FTR) and functional work ratio (FWR) were highly and moderately correlated between them (r = 0.83 and r = 0.73, respectively). The Wilcoxon statistical test revealed significant differences between CTR and CWR, as well as FTR and FWR (p < 0.05). T-test demonstrated significant differences in mean CTR-CWR and FTR-FWR, whereas Bland-Altman plots showed non-consistent bias. In addition, the chi-square test demonstrated significant differences between players below the conventional reference values and functional reference values (p < 0.001). In conclusion, TW ratios seem to provide distinct and additional information regarding the H:Q strength balance in professional soccer players. Moreover, taking into account that TW captures torque information throughout the entire range of motion, it is possible that TW ratios represent a more comprehensive assessment of muscle strength imbalance. [ABSTRACT FROM AUTHOR]

Highlights • Children at rDCD use feedback to improve their ability to fine-tune. • Children at rDCD are more dependent of the visual feedback than TD children. • Children at rDCD are more variable than TD children on fine-tune after practice. Abstract Background The production of finger force control is essential for a large number of daily activities. There is evidence that deficits in the mechanisms of accuracy and control of finger force tasks are associated with children's motor difficulties. Objective To compare the effect of practice of an isometric finger force/torque task between children with significant movement difficulty and those with no difficulty movement. Methods Twenty-four children aged between 9 and 10 years (12 at risk of developmental coordination disorder and 12 with no movement difficulty – typically developing children) were asked to produce finger force/torque control in a continuous and constant 25% of maximum voluntary torque with visual feedback during 15 s. Practice was given during five consecutive days with 15 trials per day. After the practice with visual feedback, children were asked to perform five trials without visual feedback. In these trials, feedback was removed 5 s after the start of the trial. Results Typically developing children were consistently more accurate in maintaining finger force/torque control than those children at risk of developmental coordination disorder. Children from both groups improved the performance in the task according to practice sessions. Also, children at risk of developmental coordination disorder poorly performed the task without visual feedback as they did when visual feedback was available. Conclusion The present study give support to the idea that movement difficulty is associated with finger force/torque control and children at risk of developmental coordination disorder can improve finger force/torque control with practice when visual feedback is available. [ABSTRACT FROM AUTHOR]

Purpose/Background: Strength asymmetries are related to knee injuries in intermittent sports players. The purpose of this study was to examine whether elite futsal players demonstrate strength asymmetries during knee isokinetic testing applying the Croisier et al.21 criteria. Methods: Forty male elite (27.9 ± 6.5 years) Brazilian futsal players participated in the study. The testing protocol required players to perform concentric contractions of both quadriceps and hamstring muscles at angular velocities of 60°⋅s-1 and 240°⋅s-1 and eccentric contractions of hamstring at 30°⋅s-1 and 120°⋅s-1. Conventional (concentric:concentric) and mixed (eccentric:concentric) hamstrings/quadriceps (H/Q) ratios were calculated. Subjects were determined to have an imbalanced strength profile if an athlete had at least two parameters that were asymmetrical across speeds and conditions. Asymmetry was operationally defined as peak torque asymmetry greater than 15% in bilateral comparison, and H/Q ratio less than 0.47 for conventional and 0.80 for mixed conditions. Results: Significant differences were observed between preferred and nonpreferred limbs in the concentric contractions of flexors at 240°⋅s-1 and eccentric contractions of extensors and flexors at 30°⋅s-1 and 120°⋅s-1. However, these asymmetries did not exceed 15%. The conventional and mixed H/Q ratios were greater in the preferred than in nonpreferred limbs, but only the mixed hamstringsecc/quadricepsconc in the nonpreferred limbs showed values lower than recommended (<0.80). In addition, 50% of elite futsal players had preseason strength imbalances per the developed criteria. Conclusion: The studied elite futsal players had preseason strength imbalances, which may increase the risk of hamstring injuries. Level of evidence: 3 [ABSTRACT FROM AUTHOR]

Upper-body dynamic and isometric maximum strength are essential components for success in Brazilian jiu-jitsu (BJJ). This study was aimed at analysing strength parameters in the elbow flexor and extensor muscles of BJJ practitioners. Participants (n = 28) performed maximum isometric contractions of elbow flexors and extensors to determine peak torque (PT), rate of force development (RFD), and the torque–angle (T–A) relationship at elbow angles of 45°, 60°, 75°, 90°, 105°, and 120°. Additionally, concentric and eccentric PTs were measured at 1.04 rad·s-1. Studentt-test and ANOVA were performed using α = 0.05. Elbow flexors were stronger isometrically (P < 0.001, ES = 1.23) but weaker concentrically (P < 0.05, ES = 0.54) than extensor muscles, possibly because of the extensive grip disputes and pushing of opponents in BJJ. The T–A relationship had an inverted “U”-shape. Torque differences across elbow angles were moderate (ES = 0.62) for the extensor and large (ES = 0.92) for the flexor muscles. Isometric torque was greatest for elbow angles of 105° and 75° and smallest for 45° and 120° for extensor and flexor muscles, respectively. Elbow flexors had a greater RFD than extensors, regardless of elbow angle. The present study provides comprehensive results for elbow muscle strength in BJJ practitioners. [ABSTRACT FROM PUBLISHER]

Background: Anterior cruciate ligament injury is higher in soccer athletes as compared to athletes of other sports. Risk factors for anterior cruciate ligament injury include low knee hamstring/quadriceps strength ratio and bilateral strength deficits. Purpose: To investigate isokinetic thigh muscles strength, hamstring/quadriceps strength ratio, and bilateral strength comparisons in athletes who participate in professional soccer, futsal, and beach soccer. Study Design: Cross-sectional study. Methods: Brazilian professional soccer (n=70), futsal (n=30), and beach soccer (n=12) players were isokinetically assessed to examine strength of knee extensors and flexors at 60 degrees/second in concentric mode, to measure peak torque of dominant and non-dominant limbs. Results: In the dominant limb, for extensors muscles, futsal players presented significantly lower peak torque values (223.9±33.4 Nm) than soccer (250.9±43.0 Nm; p=0.02) and beach soccer players (253.1±32.4 Nm; p=0.03). Peak torque for extensor muscles in the non-dominant limb was significantly lower in futsal (224.0±35.8 Nm) than in beach soccer players (256.8±39.8 Nm; p=0.03). Hamstring/quadriceps strength ratio for dominant limbs for futsal (57.6±10.1%), soccer (53.5±8.8%), and beach soccer (56.3±8.4%) players presented no significant differences between groups; however, the mean values were lower than recommended values found in the literature. There were no strength deficits for any of the evaluated groups when compared bilaterally. Conclusions: Futsal athletes presented lower values for quadriceps strength than soccer and beach soccer athletes. Futsal, soccer, and beach soccer players presented no strength asymmetries, but they presented with strength imbalance in hamstring/quadriceps strength ratio. Level of Evidence: 3 [ABSTRACT FROM AUTHOR]

Context: The belt-stabilized handheld dynamometer (HHD) has been used to assess the strength of knee- and hip-muscle groups. However, few researchers have examined its reliability and validity for assessing the strength of these muscles. Objective: To evaluate the intra-examiner reliability of the belt-stabilized HHD and its validity and agreement with the isokinetic dynamometer for assessing the strength of knee- and hip-muscle groups. Design: Cross-sectional study. Setting: University laboratory. Patients or Other Participants: We evaluated 26 healthy participants (13 men, 13 women; age = 23.5 ± 2.8 years, height = 1.7 ± 0.1 m, mass = 68.6 ± 12.4 kg) in 2 sessions using the belt-stabilized HHD and an isokinetic dynamometer for maximum strength of the hip adductors, abductors, flexors, extensors, internal rotators, and external rotators and the knee flexors and extensors. Main Outcome Measure(s): We used reliability values provided by the intraclass correlation coefficient (2,3), standard error of measurement (SEM and percentage SEM), and minimal detectable change; correlation values comparing the beltstabilized HHD and the isokinetic instrument using the Pearson correlation coefficient (r); and the mean difference in values comparing the 2 instruments using the Bland-Altman method. Results: The intrarater HHD reliability was excellent for most measurements (range = 0.80-0.96; SEM = 1.3-5.3 kilograms of force or 4.8-18.9 Nm, percentage SEM = 7.0%-22.0%, minimal detectable change = 3.6-18.8 kilograms of force or 13.2-52.4 Nm) and was moderate only for bilateral knee flexion and left hip internal rotation (intraclass correlation coefficient [2,3] = 0.62-0.66 and 0.70, respectively). Correlation with the isokinetic dynamometer was moderate to high (r = 0.60-0.90), but the absolute values did not demonstrate concordance between results using the Bland-Altman method. Conclusions: The belt-stabilized HHD measurements were reliable, and although they did not agree with those from the isokinetic dynamometer, the values were correlated for the hipand knee-muscle groups. [ABSTRACT FROM AUTHOR]

BACKGROUND: Range of Motion (ROM) and passive torque have been widely used to evaluate flexibility stretching protocols, but little attention has been given to the reliability of these measurements. OBJECTIVE: To verify the interday reliability of isokinetic dynamometer for assessing ROM measures based on discomfort perception (initial and maximum), static and dynamic measures of passive torque during a leg extension movement on a young adult sample. METHODS: Twenty students (13 men; 7 women) aged between 18 and 30 years attended the laboratory to perform the test and retest with 2-7 days interval. The evaluations included: Initial Discomfort Angle (IDA), Passive dynamic torque (Stiffness), Passive static torque (Viscoelastic Stress Relaxation-VSR) and Maximal Discomfort Angle (MDA). Reliability was tested by the Intraclass Correlation Coefficient (ICC), one-sample t-test and Bland-Altman charts. RESULTS: Stiffness (ICC = 0.93), IDA (ICC = 0.90) and MDA (ICC = 0.87) showed excellent reliability values, while VSR had moderate ones (ICC = 0.59). Bland-Altman plots indicated bias close or equal to zero. The one-sample t-test for all measures reinforced the absence of a systematic error. CONCLUSIONS: Dynamic and static stiffness measures and ROM based on the subject's discomfort perception may be applied to relevant clinical issues. [ABSTRACT FROM AUTHOR]

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Background: Brazilian Jiu-Jitsu (BJJ) athletes can be divided into two combat styles: pass fighters (PFs) and guard fighters (GFs). Flexibility of the posterior chain muscles is highly necessary in these athletes, especially in GFs. On the other hand, isometric strength of the trunk extensors is required in PFs. Handgrip strength is important in holding the kimono of the opponent, and symmetrical lower-limb strength is important for the prevention of injuries due to the overload caused by training. Purpose: The aim of this study was to compare the biomechanical profiles of BJJ athletes with different combat styles using the following outcome measures: flexibility, trunk extensor isometric endurance, postural balance, handgrip isometric endurance and lower-limb muscle strength. Methods: A cross-sectional study was conducted using 19 GFs and 19 PFs. The sit-and-reach test was used to evaluate the flexibility of the posterior chain muscles. The Biodex Balance System® was used to evaluate balance. A handgrip dynamometer and a dorsal dynamometer were used to evaluate handgrip and trunk extensor endurance, respectively. Quadriceps and hamstring strength were evaluated with an isokinetic dynamometer at 60°/s. Results: No differences were observed between groups in terms of flexibility, balance, handgrip isometric endurance or quadriceps and hamstring strength; however, PFs (81.33) showed more isometric trunk extension endurance than GFs (68.85) (p= 0.02). Both groups had low values for hamstring/quadriceps ratio. Conclusion: No significant biomechanical differences were observed between PFs and GFs. Level of Evidence: 2b [ABSTRACT FROM AUTHOR]

Introduction: Declines of static postural balance and muscle strength, especially of lower limbs are strong predictors of falls in the elderly. Objective: The objective of this study was to identify the possible correlation between static postural balance, falls and isokinetic torque peak of knee extensors and flexors in the elderly. Methods: A cross-sectional study with anthropometric evaluation of static postural balance in unipodal limb support was performed using the force platform, flexural strength test and knee extension of the dominant limb using the isokinetic dynamometer and the application of a structured questionnaire on falls. They agreed to participate in the study 106 volunteers of both sexes through the signing of the free and informed consent. The data were treated in the Statistical Package for the Social Sciences program version 20.0. Results: There was a weak positive correlation between center of pressure (COP) area and peak flexion torque (r=0.204, p=0.041) and extension (r=0.228; p=0.022) of the knee, as well as peak extension (r=0.319, p=0.001) and lateral mean (r=0.324, p=0.001). A moderate positive correlation between COP area and anteroposterior velocity (r=0.694, p=0.000) and lateral mean (r = 0.646; p = 0.000) and strong positive correlation was found only between peak flexion torque and knee extension (r=0.719, p=0.000). Conclusion: There was a weak correlation between static postural balance and dominant lower limb muscle strength, and there was no correlation between falls and lower limb muscle strength, or between falls and static postural balance in the studied sample. [ABSTRACT FROM AUTHOR]

Background: Subcutaneous adipose tissue may influence the transmission of electrical stimuli through to the skin, thus affecting both evoked torque and comfort perception associated with neuromuscular electrical stimulation (NMES). This could seriously affect the effectiveness of NMES for either rehabilitation or sports purposes. Objective: To investigate the effects of skinfold thickness (SFT) on maximal NMES current intensity, NMES-evoked torque, and NMES-induced discomfort. Method: First, we compared NMES current intensity, NMES-induced discomfort, and NMES-evoked torque between two subgroups of subjects with thicker (n=10; 20.7 mm) vs. thinner (n=10; 29.4 mm) SFT. Second, we correlated SFT to NMES current intensity, NMES-induced discomfort, and NMES-evoked knee extension torque in 20 healthy women. The NMES-evoked torque was normalized to the maximal voluntary contraction (MVC) torque. The discomfort induced by NMES was assessed with a visual analog scale (VAS). Results: NMES-evoked torque was 27.5% lower in subjects with thicker SFT (p=0.01) while maximal current intensity was 24.2% lower in subjects with thinner SFT (p=0.01). A positive correlation was found between current intensity and SFT (R=0.540,P=0.017). A negative correlation was found between NMES-evoked torque and SFT(r=-0.563, p=0.012).No significant correlation was observed between discomfort scores and SFT (rs=0.15,p=0.53). Conclusion: These results suggest that the amount of subcutaneous adipose tissue (as reflected by skinfold thickness) affected NMES current intensity and NMES-evoked torque, but had no effect on discomfort perception. Our findings may help physical therapists to better understand the impact of SFT on NMES and to design more rational stimulation strategies. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to assess and monitor the peak torque of the knee extensor and flexor muscles in flexion and extension and the reports of musculoskeletal complaints in members of the main Brazilian Paralympic athletics team through 1 yr. Design: Fourteen healthy athletes from both sexes were assessed three times in 1 yr. The volunteers were assessed for the presence of musculoskeletal complaints and muscle strength at three time points: (1) at the onset of the preparatory phase on December 2009, (2) at a follow-up assessment on June 2010, and (3) before actual competition on December 2010. The athletes' self-reported musculoskeletal complaints were assessed in structured interviews, and the muscle strength was assessed by means of isokinetic dynamometry. Results: The knee flexor and extensor muscle strength exhibited significant increase in both the right and left lower limbs at the second and third assessments compared with the first one (P G 0.05). Muscle imbalance was associated with knee and thigh complaints at all three assessments (P G 0.05). Conclusions: The knee flexor and extensor muscle strength exhibited a gradual increase in both lower limbs during the course of the three assessments. In parallel, muscle imbalance was associated with the occurrence of knee and thigh complaints. [ABSTRACT FROM AUTHOR]

The article presents a study to measure knee strength and asymmetry in soccer players and the variation of these factors as per field positions of goalkeepers, side and central backs, central defender and central attacking midfielders and forwards. The study proved that all field positions except that of goalkeepers have similar functional strength ratios and side-to-side asymmetries. It also proved that isokinetic strength for goalkeeper should be more compared to other positions.

BACKGROUND: The isokinetic hamstrings to quadriceps (H:Q) dynamic control ratio (DCR) is frequently used to assess muscle imbalances and to screen for potential risks of knee injuries in sports.OBJECTIVE: To investigate the correlation between knee conventional ratio (CR) and DCR in elite soccer players and check for a possible relationship. A positive correlation would indicate that the CR could predict DCR.METHODS: One hundred and thirteen Brazilian elite soccer players (25.2 ± 5.3 yrs) performed maximal dominant and nondominant knee concentric (CON) and eccentric (ECC) strength tests at 60°/s on an isokinetic dynamometer in order to calculate CR and DCR.RESULTS: A significant positive correlation between ratios was found for the dominant and non-dominant knees (r=0.54 and 0.62; p < 0.001 which translated into low R^{2} values of 0.29 and 0.39, respectively. CONCLUSION: This suggests that the CR may not replace the DCR and is thus of a limited clinical value in assessing knee muscles imbalance. On the other hand, the paper presents for the first time a robust reference frame for the isokinetic strength and related ratios of the two major knee muscles in soccer players. [ABSTRACT FROM AUTHOR]

BACKGROUND: Few studies thus far have investigated the relationship between body composition (in particular, bone components) and isokinetic strength performance. OBJECTIVE: To determine the relationship between bone mineral content (BMC), bone mineral density (BMD), and fat-free mass (FFM) with isokinetic strength performance variables in professional soccer players. METHODS: We recruited 20 elite male soccer players from the Brazilian league’s first division teams. Participants underwent a concentric isokinetic evaluation of knee flexor and extensor muscles. Dual-energy X-ray absorptiometry (DXA) was used to determine body composition. The relationships between variables were analyzed using Pearson’s product-moment correlation coefficient. RESULTS: Body composition variables were correlated with the strength output of knee flexor and extensor muscles in both lower limbs. FFM and BMC explained at least 50% of the variation in peak knee flexion and extension torque while BMD did not have the same effect. CONCLUSIONS: The relationships reported in this study indicate that the use of isokinetics and DXA in soccer players should be further investigated both for measuring athletic performance and for relevant clinical assessment. [ABSTRACT FROM AUTHOR]

The article reports on research which investigated the effect constant torque (CT) and constant angle (CA) stretching had on range of motion, muscle passive properties and stretch discomfort perception in 23 sedentary men. Researchers found that the maximum range of motion increased with both CA and CT and that a greater increase in maximum range of motion seen with the CT stretch may be explained by greater changes in the biomechanical properties of the muscle tendon unit and stretch tolerance.

The aim of this study was to test the hypothesis that magnesium supplementation influences the physical performance of volleyball players, as the efficacy of this approach remains questionable. Twenty-five professional male volleyball players were assigned randomly to experimental (350 mg Mg · d–1, 4 weeks) and control groups (500 mg maltodextrin · d–1, 4 weeks) maintaining inter-group homogeneity of urinary magnesium. Erythrocyte, plasma and urinary magnesium levels, plasma creatine kinase activity, lactate production, maximal oxygen uptake (VO2max) and plyometric (squat jump, countermovement jump, countermovement jump with arm swing) and isokinetic (peak torque, potency and total work) performances were evaluated before (T0) and after (T1) supplementation. Levels of erythrocyte and urinary magnesium and creatine kinase activity and VO2max remained within normal ranges in both groups. Plasma magnesium decreased significantly only within the experimental group. Significant decreases in lactate production and significant increases (of up to 3 cm) in countermovement jump and countermovement jump with arm swing values were detected in the experimental group following magnesium supplementation, but not in the control group at T1. It is concluded that magnesium supplementation improved alactic anaerobic metabolism, even though the players were not magnesium-deficient. [ABSTRACT FROM AUTHOR]

STUDY DESIGN: Repeated-measures, within-subject crossover trial. OBJECTIVES: The primary objective was to assess the effect of the burst-duty-cycle parameters of medium-frequency alternating current on the maximum electrically induced torque of the quadriceps femoris. The secondary objectives were to evaluate the amount of discomfort tolerated and the maximum current amplitude delivered for each electrical-stimulation condition. BACKGROUND: Neuromuscular electrical stimulation used for muscle strengthening can improve functional performance. However, the electrical-stimulation parameters to achieve optimal outcomes are still unknown. Previous studies have demonstrated that the characteristics of the burst duty cycle of medium-frequency alternating current influence torque-generation levels and perception of sensory discomfort. METHODS: The maximum electrically induced torque was assessed with a medium-frequency alternating current, with a carrier frequency of 2500 Hz and a modulated frequency of 50 Hz. The current amplitude was gradually increased to the point of the participant's maximum tolerance level. The testing sequence for the 3 burst duty cycles (20%, 35%, and 50%) was performed in a randomized order. RESULTS: Electrical stimulation using a 20% burst duty cycle produced an electrically induced torque greater than the 35% (P = .01) and 50% (P<.01) burst duty cycles, with no difference between the 35% and 50% burst duty cycles (P = .46). There was no difference in the amount of sensory discomfort produced by the 3 durations of burst duty cycles (P = .34). There was also no difference between the 3 conditions for the maximum current amplitude tolerated (P = .62). CONCLUSION: The burst duty cycle of 20% of medium-frequency alternating current, compared to burst duty cycles of 35% and 50%, produced higher peak torque of the quadriceps femoris in professional soccer players. There was no difference in discomfort produced and current amplitude tolerated between the different burst-duty-cycle conditions. J Orthop Sports Phys Ther 2013;43(12):920-926. Epub 30 October 2013. doi:10.2519/jospt.2013.4656 [ABSTRACT FROM AUTHOR]

Background: Data obtained on an isokinetic dynamometer are useful to characterize muscle status and have been reported in muscle imbalance studies in different types of sport. However, few studies have assessed elite handball players to establish reference values. Objective: The purpose of this study was to compare, for the dominant (D) and non-dominant (ND) side, the isokinetic profile of shoulder rotator muscle strength between male handball players (H) and asymptomatic non-athletes (NA). Method: Isokinetic concentric and eccentric strength tests for D upper limbs were performed by the H group (n=20) and the NA group (n=12). Internal and external rotator muscle peak torque in concentric action was assessed at 60°/s and 300°/s and in eccentric action at 300°/s. We also calculated conventional balance (the ratio of external rotator peak torque to internal rotator peak torque in concentric action) and functional balance (the ratio of external rotator peak torque in eccentric action to internal rotator peak torque in concentric action). Results: In the H group, dominant limbs were stronger in concentric action for external rotation at 60 and 300°/s. The conventional balance ratio for the D side was significantly lower at 60 and 300°/s for H compared to NA. The functional ratio for the D side was significantly lower at 300º/s for H compared to NA. Conclusions: Compared to asymptomatic non-athletes, handball players presented significant muscular imbalance resulting from daily sports practice, a known risk factor for shoulder injuries. [ABSTRACT FROM AUTHOR]

Investigations have demonstrated that progressive lower-body compression garments can enhance jump power and running economy. Recently, the use of upper-body compression garments has become popular in sports that require muscular strength, endurance, and power. However, the benefits of these garments on muscular performance still need to be investigated. The aim of this study was investigate the effects of wearing compression sleeve on force production and muscle work of the elbow flexors. Eight healthy resistance trained young men volunteered to take part in this study. Testing was conducted using a randomized treatment design with two experimental conditions consisting of: 1) compression sleeve, and 2) placebo sleeve with no compression. Peak torque (PT) and total work (TW) testing consisted of four sets of 10 maximal isokinetic elbow flexion repetitions at 60°.s-1. No significant differences were found between the compression and placebo conditions. However, PT and TW decreased significantly across sets for both conditions. These results indicate that compression sleeves commonly worn by athletes and fitness participants do not contribute to enhance elbow flexion muscle strength or work capacity. [ABSTRACT FROM AUTHOR]

BACKGROUND AND OBJECTIVE: The quadriceps rate of torque development (RTD) is frequently used to evaluate explosive performance, but its functional meaning has been questioned. Thus, the aim of this study was to investigate if isometric quadriceps RTD correlates with multi-joint dynamic performance and if it has greater correlation with dynamic performance than with a single-joint isokinetic test in soccer players. METHODS: Thirty-nine male soccer players (age 21 ± 5 years, body mass 75 ± 7.5 kg, height 179 ± 5 cm) performed five maximal concentric knee extension isokinetic contractions at a velocity of 180°/s, followed by three maximal voluntary isometric contractions (MVIC) with knee angle of 60°, and five countermovement jumps (CMJ). The RTD was derived from MIVC over various time intervals (of 0.05, 0.1, 0.2, 0.3 seconds, and peak RTD) and CMJ height was calculated by flight time method. Pearson Product Moment Correlations were used to determine the relationships between variables. RESULTS: Absolute and relative isokinetic PT correlated positively with CMJ height (p< 0.001, r=0.513 and p=0.0007, r=0.521, respectively). However, none of the isometric RTD measures showed significant relationship with CMJ height (p> 0.05, r from -0.272 to 0.296). CONCLUSION: These results indicate that single-joint isometric RTD does not correlate with dynamic multi-joint performance. Thus, more specific tests in relation to contraction type, velocity and/or movement pattern should be used. [ABSTRACT FROM AUTHOR]

The article discusses research which was conducted to perform an analysis of lower limb asymmetries in soccer players and compare analyses which used isokinetic assessment or vertical jump tests. Researchers evaluated 46 players. They found that both the isokinetic and jump tests were independent methods which could be used to assess asymmetries and that both could be used together to obtain maximum information.

Background: The extent to which muscle length affects force production in paretic lower limb muscles after stroke in comparison to controls has not been established. Objectives: To investigate knee flexor strength deficits dependent on hip joint position in adults with hemiparesis and compare with healthy controls. Method: a cross-sectional study with ten subjects with chronic (63±40 months) hemiparesis with mild to moderate lower limb paresis (Fugl-Meyer score 26±3) and 10 neurologically healthy controls. Isometric knee flexion strength with the hip positioned at 90° and 0° of flexion was assessed randomly on the paretic and non-paretic side of hemiparetic subjects and healthy controls. Subjects were asked to perform a maximal isometric contraction sustained for four seconds and measured by a dynamometer. The ratio of knee flexor strength between these two hip positions was calculated: Hip 0°/Hip 90°. Also, locomotor capacity was evaluated by the timed up and go test and by walking velocity over 10 meters. Results: In subjects with hemiparesis, absolute knee flexion torque decreased (p<0.001) with the hip in extension (at 0°). The ratio of knee flexor torque Hip 0°/Hip 90° on the paretic side in hemiparetics was lower than in controls (p=0.02). Conclusions: Weakness dependent on joint position is more significant in the paretic lower limb of adults with hemiparesis when compared to controls. More attention should be given to lower limb muscle strengthening exercises in individuals with stroke, with emphasis on the strengthening exercises in positions in which the muscle is shortened. [ABSTRACT FROM AUTHOR]

Background: Low-frequency pulsed current (LFPC) and Russian current (RC), a type of kilohertz-frequency alternating current, have been frequently used for muscle strengthening in rehabilitation programs. Despite the popularity of these current types, it is unclear which is most effectively able to generate a similar submaximal torque with minimal discomfort and current amplitude. Objective: To compare discomfort and current amplitude between LFPC and RC to achieve a knee extensor torque of 10% of the maximal isometric voluntary contraction (MIVC). Methods: Twenty-two healthy subjects were subjected to three electrically elicited knee extensor submaximal contractions (10% MIVC) that were sustained for 10 seconds. The current amplitude required to achieve 10% MIVC and subjective discomfort were assessed directly by the electrical stimulator and with the Visual Analogue Pain Scale, respectively. A paired t-test was used to determine differences between the electrical currents ( α = 0.05). Results: LFPC required significantly lower current amplitude (15%) and a lower discomfort level (50%) to achieve 10% of MIVC compared to RC. Conclusion: LFPC current seems to be more effective than RC with respect to discomfort level and current amplitude to produce 10% of MIVC. [ABSTRACT FROM AUTHOR]

Background: Osteoarthritis (OA) is a chronic-degenerative disease. The knee is the most commonly affected joint and the symptoms are generally attributed to quadriceps muscle weakness. However, few studies have evaluated this relationship in a population with early stages of knee OA. Objective: To investigate whether a correlation among the knee extensor torque and the three subscales of the WOMAC questionnaire in men with early stages of knee OA exists. Method: Twenty-one men with knee OA grades I or II (according to Kellgren and Lawrence* criteria) participated in this study. The concentric and eccentric knee extensor torque were assessed using a Biodex System 3 Pro® isokinetic dynamometer, at a speed of 90°/s. Self-reported symptoms and disability were assessed using the WOMAC questionnaire. Spearman's correlation coefficient was used to test the relationship between the dependent variables (three subscales of WOMAC questionnaire) and the independent variables (average knee extensor peak torque). Results: We found a strong negative correlation between the concentric extensor torque and pain (r=-0.7, p<0.001) and a moderate and negative correlation among the concentric extensor torque and stiffness (r=-0.62, p=0.002) and physical function (r=-0.54, p=0.011). Eccentric extensor torque presented a moderate and negative correlation with the three subscales of the WOMAC (r=-0.40 to 0.69, p<0.05). Conclusions: The concentric and eccentric knee extensor torque is significantly correlated with self-report symptoms of patients in initial stages of knee OA. Therefore, the strengthening of the quadriceps muscles, through concentric and eccentric exercise is indicated for these patients in order to minimize these symptoms. Trial registration: number RBR-8q4zfh. [ABSTRACT FROM AUTHOR]

Background: The patellar tendon has limited ability to heal after harvesting its central third. Platelet-rich plasma (PRP) could improve patellar tendon healing.Hypothesis: Adding PRP to the patellar tendon harvest site would improve donor site healing and improve clinical outcome at 6 months after anterior cruciate ligament (ACL) reconstruction with a patellar tendon graft.Study Design: Randomized controlled trial; Level of evidence, 1.Methods: Twenty-seven patients were randomly divided to receive (n = 12) or not receive (n = 15) PRP in the patellar tendon harvest site during ACL reconstruction. The primary outcome was magnetic resonance imaging (MRI) assessment of patellar tendon healing (gap area) after 6 months. Secondary outcomes were questionnaires and isokinetic testing of ACL reconstruction with a patellar tendon graft comparing both groups.Results: Patellar tendon gap area was significantly smaller in the PRP group (4.9 ± 5.3 mm2; 95% confidence interval [CI], 1.1-8.8) than in the control group (9.4 ± 4.4 mm2; 95% CI, 6.6-12.2; P = .046). Visual analog scale score for pain was lower in the PRP group immediately postoperatively (3.8 ± 1.0; 95% CI, 3.18-4.49) than in the control group (5.1 ± 1.4; 95% CI, 4.24-5.90; P = .02). There were no differences after 6 months in questionnaire and isokinetic testing results comparing both groups.Conclusion: We showed that PRP had a positive effect on patellar tendon harvest site healing on MRI after 6 months and also reduced pain in the immediate postoperative period. Questionnaire and isokinetic testing results were not different between the groups at 6 months. [ABSTRACT FROM PUBLISHER]