Flexor Peak Torque Research Articles

Trunk flexor and extensor strength and the kinematic parameters of gait among stroke survivors

Objective To correlate the isokinetic strength of stroke survivors′ trunk flexors and extensors with the kinematic parameters of their gait. Methods Thirty stroke survivors and 30 healthy counterparts formed an observation group and a control group. The strength of everyone′s trunk flexors and extensors was measured isokinetically, including the flexor peak torque (FPT), extensor peak torque (EPT) and the ratio of the two (F/E). The test velocities were 30°/s, 60°/s and 90°/s. And the kinematic parameters of their gait, including the step length, stride, velocity, frequency, width and cycle time were measured using a 3D gait analysis system, as well as the percentage of stance phase, swing phase, double support phase and single support phase. Results No significant differences were found between the average FPT, EPT or F/E of the two groups at any of the three test velocities. At the 30°/s test velocity the average FPT, EPT and F/E of the observation group were all positively correlated with the average step length, stride, velocity, steps/min, width and cycle time, as well as with the stance phase, swing phase, double support phase and single support phase percentages. The strongest correlation was between F/E and velocity (r=0.57), followed by frequency (r=0.54). Conclusion litating the walking ability of stroke survivors and correcting their gait should focus on strengthening the trunk muscles and optimizing their coordination. Key words: Stroke; Trunk muscles; Muscle strength; Gait

Leg press exercise can reduce functional hamstring:quadriceps ratio in the elderly

The aim of this study was to investigate whether 12 weeks of leg press strength training exercise could affect the conventional and functional hamstring:quadriceps ratios in the elderly. Twelve elderly participants were submitted to a 12 week progressive training protocol (two sessions/week) using a 45° leg press exercise. A significant increase in the one repetition maximum was observed after 4, 8, and 12 weeks (p = 0.001, p < 0.001, and p < 0.001, respectively) compared to week 0 and after 8 (p = 0.011) and 12 weeks (p = 0.001) compared to week 4. The concentric knee extensor peak torque was significantly higher at weeks 8 (p = 0.001) and 12 (p = 0.024) compared to week 0. There was no change in the concentric and eccentric knee flexor peak torques (p = 0.629 and 0.274, respectively) and conventional ratio (p > 0.314) after 12 weeks of training. The functional ratio (eccentric knee flexor peak torque:concentric knee extensor peak torque) reduced significantly after 8 (p = 0.034) and 12 (p = 0.036) weeks of strength training. Although the 45° leg press exercise requires knee extensor and flexor, hip extensor, and plantar flexor muscle strength, our findings suggest that the isolated use of the 45° leg press exercise reduces the knee functional ratio after 8 weeks of training. Therefore, 45° leg press exercise alone, without a hamstring exercise, should not be recommended for elderly individuals.

Effects of a Modified Ballet Class on Strength and Jumping Ability in College Ballet Dancers.

The ability to jump high with precision is an important component of the ballet dancer's technique. The aim of this study was to evaluate the effect of a modified ballet class on strength and jumping ability in high level female dancers. Seventeen female ballet students were divided into two groups, experimental and control, and tested before and after an 8-week, 2 times/week intervention for peak torque of knee extensors and flexors at 60°and 180°, and jumping ability (squat jump, countermovement jump, countermovement with arm swing jump, sauté in first position, and sauté in first position with port de bras). Statistical analysis was performed using Analysis of Variance (Anova 2x2) with repeated measure of factor time (pre and post). T-test with Bonferroni adjustment was used to assess any differences between groups. The experimental group showed improvement in height (7.7%), takeoff velocity (4.0%), and power (5.1%) of the squat jump. In addition, increases were revealed in peak (60°, 11.9%; 180°, 7.8%) and relative peak torque (60°, 13.2%; 180°, 9.2%) of the right knee flexors. Moreover, enhancements of the knee flexor-extensor strength ratio in both angular velocities were found (60°, 10.4%; 180°, 9.7%). These outcomes suggest that the proposed program could help ballet dancers improve the height of their vertical jumps and leg strength.

지적장애 축구선수들의 하지강화프로그램이 하지근력과 균형능력에 미치는 영향

This study conducted an strengthening legs exercise program with soccer players with intellectual disabilities for 12 weeks to examine the effects on lower extremity strength and balance. The following conclusions were drawn. First, in the change of lower extremity strength before and after strengthening legs exercise program, the exercise group did not show a significant difference in right thigh flexor and left thigh extensor but showed a significant difference in the peak torque of left thigh flexor(p Second, for a change of balance before and after strengthening legs exercise program, the exercise group did not show a significant difference in surface area, travel length, average speed. Taken together, we could see that the strengthening program, which included plyometric training and weight training, had a positive effect. However, it is considered that there is no statistically significant result in the balance ability, so it is necessary to review the constitution of the exercise program. However, if the regular training method and the strengthening program are performed regularly, And it is thought that it can be an effective training method for prevention of injuries.

The relationship between jumping performance, isokinetic strength and dynamic postural control in elite youth soccer players.

The aim of this study was to investigate the relationship between vertical jumping performance, isokinetic strength of knee extensors/flexors, and postural priority and to describe a multiple regression model that accounts for the effects of selected parameters of isokinetic strength and postural priority on vertical jumping performance. Thirty-one professional male soccer players, aged from 17 to 20 years, participated in this study (age, mean±SD: 18.6±1.26 years; height: 1.78±0.74 m and weight: 73.1±6.77 kg). The correlations between isokinetic knee strength, jumping performance, and postural control were evaluated using the Pearson correlation coefficient. A linear regression model was used to evaluate the effect of hamstrings and quadriceps peak torque of both legs at 60º·s-1, total work of both legs at 240º·s-1, and postural priority on jumping performance. The peak torque of right leg knee flexor (quadriceps) muscles, evaluated at 60º·s-1 speed, showed correlations with counter movement jump, 30 second jumping and squat jump (P=0.005, P=0.003, and P=0.007, respectively). We also observed a strong relationship between counter movement jump and 30 second jumping and peak torque of left leg evaluated at the same speed of 60º·s-1 (P=0.26 and P=0.22, respectively). No significant correlations were found between any of the jumping tests and peak torque of knee extensors of both legs at 60º·s-1. For the 30 second jumping test, it appears that jumping endurance has a significant relationship with total work of knee flexors for right and left legs at 240º·s-1. The results of this study demonstrate practical implications for soccer performance, but further exploration is required.

The Role of Eccentric Strength in 180° Turns in Female Soccer Players.

Previous studies have reported an association between eccentric strength (ECC-STR) and change of direction (COD) ability. Little is known about how ECC-STR facilitates COD maneuvers. The aim of this study was to examine the role of ECC-STR during a 180° COD task in 18 female soccer players. Each player performed six trials of a 180° COD task whereby three-dimensional motion data from 10 Qualisys Pro-Reflex infrared cameras (240 Hz) and ground reaction forces (GRFs) from two AMTI force platforms (1200 Hz) were collected. Relative eccentric knee extensor (ECC-EXT) and flexor (ECC-FLEX) peak torque was collected from both limbs at 60°·s−1 using a Kin Com isokinetic dynamometer. Large correlations were revealed between COD performance (time to complete 5 m approach, 180° turn, 5 m return) and ECC-EXT (R = −0.674) and ECC-FLEX (R = −0.603). Moderate to large correlations were observed between approach velocity (AV) and COD performance (R = −0.484) and ECC-EXT (R = 0.724). Stronger participants (n = 9) recorded significantly (p < 0.05) faster AV (4.01 ± 0.18 vs. 3.74 ± 0.24 m·s−1, d = 1.27) and a greater reduction in velocity (−1.55 ± 0.17 vs. −1.37 ± 0.21 m·s−1, d = −0.94) during penultimate contact than weaker (n = 9) subjects. Greater ECC-STR is associated with faster COD performance in female soccer players, as stronger players are better able to decelerate during penultimate contact from faster approach velocities.

Effect of isokinetic training on muscle strength and postural balance in children with Down's syndrome.

Children with Down's syndrome (DS) often have greater postural sway and delay in motor development. Muscle weakness and hypotonia, particularly of the lower extremities, are theorized to impair their overall physical health and ability to perform daily activities. Therefore, the aim of this study was to investigate the effects of isokinetic training on muscle strength and postural balance in children with DS. Thirty-one children with DS ranging in age from 9 to 12 years were assigned randomly into two groups. The control group received the conventional physical therapy, whereas the study group received the same therapy as the control group in addition to the isokinetic training 3 days a week for 12 weeks. Measurement of stability indices using the Biodex Stability System as well as peak torque of knee flexors and extensors of both sides using the isokinetic dynamometer was performed before and after 12 weeks of the treatment program. Each group showed significant improvements in postural balance and peak torque of knee flexors and extensors (P<0.05), with significantly greater improvements observed in the study group compared with the control group (P<0.05). These outcomes indicated that participation in the isokinetic training program induced greater improvements in muscle strength and postural balance in children with DS.

Sex Differences in the Influence of Leg Strength on Arterial Stiffness.

INTRODUCTION: Acute resistance exercise has been associated with increased central artery stiffness and muscle strength has been shown to be inversely associated with arterial stiffness. However, many studies have only included males with little research conducted including females. Pre-menopausal females typically have lower resting arterial stiffness, yet the relationship between strength and arterial stiffness responses is unknown for females. PURPOSE: To determine the relationship between quadriceps and hamstring strength and the acute arterial stiffness response following resistance exercise. METHODS: Eleven males (28 ± 5 yrs; 24.6 ± 2.0 kg/m2) and eight females (26 ± 4 yrs; 22.5 ± 2.3 kg/m2) completed maximal isokinetic knee extension and flexion (3 sets of 10 repetitions) on a force dynamometer. Central pulse wave velocity (PWV) was estimated by brachial oscillometric blood pressure waveforms at baseline and 5 min post-exercise. Bivariate correlations were performed to examine the linear relationship between leg strength and change in PWV. Relative leg strength data was adjusted for lean body mass measured by dual-energy X-ray absorptiometry. RESULTS: Only females exhibited positive correlations between changes in PWV and peak flexor torque (p < 0.05), relative peak flexor torque (p < 0.05), relative flexor power (p < 0.05) and relative average power (p < 0.05). PWV did not change from rest to 5 min post-exercise in females (5.2 ± 0.2 to 5.2 ± 0.3 m/s) but did significantly increase in males (5.2 ± 0.6 to 5.4 ± 0.6 m/s). CONCLUSION: The results suggest that leg strength is positively associated with changes in arterial stiffness in females, but not males, despite the group mean for females showing no change in stiffness. Therefore, females with higher leg strength have greater changes in stiffness after a bout of resistance exercise.Table: No title available.

The Lower Extremity Strength, Bilateral And Ipsilateral Strength Assymetries In Elite Female Soccer Players

BACKGROUND: Soccer frequently involves one-sided activities such as kicking, tackling and passing, which may lead to strength asymmetries (SA), and effect of the age is not well studied. PURPOSE: The aim was to investigate effect of limb-dominance and ages through relative strength measures of knee extensors (KE), knee flexors (KF), bilateral strength ratio (QQ, HH), and ipsilateral strength ratio (HQ) in youth elite female soccer players. METHODS: National level female soccer players of three age categories (Under 16 years =17, Under 17 years =16, Under 18 years =16 players) performed isokinetic strength testing for KE, KF at three velocities (60, 180, 300 °.s-1) for the dominant (DL) and non-dominant leg (NL). Mean peak torque of extensors (PTE) and flexors (PTF) values were calculated in Newton-meters relatively to body weight (N·m·kg−1) and strength ratios were derived from peak torques. Three-way Mixed-design ANOVA with two between subject effect (age, limb dominancy) and one within subject effect (angular velocity) were used. Bonferonni’s post-hoc test was employed due to the multiple comparisons. Effect size was assessed using the ηp2 coefficient. RESULTS: Significant age effect was observed in PTE and PTF (PTE: F2,91 = 4.60, p = 0.013, ηp2=0.09, PTF: F2,91 = 11.31, p = 0.001, ηp2=0.20). Conversely, age did not indicate significantly effect on bilateral strength ratio (QQ, HH) (F2,91 = 2.00, p = 0.141, η2=0.04) a HQ (HQ: F2,90 = 1.03, p = 0.361, η2=0.02). Significant limb dominance effect was not identified in PTE, PTF and HQ (PTE: F1,91 = 0.06, p = 0.810, η2=0.01, PTF: F2,91 = 0.30, p = 0.587, ηp2=0.00, HQ: F2,91 = 3.50, p = 0.065, η2=0.04). We found significantly higher strength asymmetries in KF compare to KF (F1,91 = 15.89, p = 0.000, η2=0.15). Post-hoc analysis showed a significant difference in PTE between U15 vs. U19 and in PTF between U16 vs. older age category (U17, U19). The higher bilateral strength differences (QQ > 10%) we found in following age categories (U16 = 53%, U17 = 50%, U19 = 56%). Moreover in knee flexors (HQ>10%) were even higher strength asymmetries (U16 = 71%, U17 =75%, U19=79%). CONCLUSIONS: The current results indicated effect of age on PTE, PTF but not in limb dominance. More attention should be paid to knee flexors where higher occurrence of strength asymmetries were found.

The Relationship Between Academic Stress and Skeletal Muscle Performance

Student athletes are required to perform both in the classroom and on the field; balancing these commitments can be stressful. It is common to question the burden of athletic demands on student scholarship. However, the inverse is seldom asked: how do scholastic stresses affect athletic performance? PURPOSE: To test the effect of psychological stress on skeletal muscle performance in college students. METHODS: We enrolled 23 recreationally active students (10 men, 13 women) from a D1 university. Skeletal muscle function was assessed via quadriceps extension and hamstring flexion using a Cybex HUMAC NORM dynamometer. Psychological stress was measured with the Cohen Perceived Stress Scale. Subjects were evaluated at two time points: a high stress period (exams) and a low stress period (no exams). A history of injury excluded subjects from participation; nightly sleep, history of exercise, and recent exercise were controlled. Independent variables were stress, sex, age, weight, BMI, academic load, and participation in organized sports (club or intramural). Dependent variables were peak torque (ft/lb) and time to achieve peak torque (sec). Differences in muscle performance between high and low stress periods were assessed with t-tests. Linear regressions analyzed the effect of psychological stress on muscle performance. RESULTS: Subjects were 20.2 ± 1.1 years old, had peak flexor torque of 87.4 ± 19.7 ft/lb (achieved in 0.58 ± 0.12 sec), and peak extensor torque of 145.2 ± 37.5 ft/lb (achieved in 0.58 ± 0.15 sec). T-tests found no differences between low and high stress periods in peak torque or time to achieve peak torque (p>0.090). Linear regression found increases in psychological stress to correlate with improvements in the overall rate of force development (p=0.004). The effect was strongest with flexors: for each point that stress increased, time to achieve peak torque was 2.4% faster (p=0.002). CONCLUSION: Despite a small sample size, these findings suggest psychological stress may enhance force development. A possible mechanism could be sympathetically-mediated potentiation of calcium release. While academic stress presents many challenges for student-athletes, it does not appear to be detrimental to muscular performance.

Transcranial Direct Current Stimulation Does Not Affect Lower Extremity Muscle Strength Training in Healthy Individuals: A Triple-Blind, Sham-Controlled Study.

The present study investigated the effects of anodal transcranial direct current stimulation (tDCS) on lower extremity muscle strength training in 24 healthy participants. In this triple-blind, sham-controlled study, participants were randomly allocated to the anodal tDCS plus muscle strength training (anodal tDCS) group or sham tDCS plus muscle strength training (sham tDCS) group. Anodal tDCS (2 mA) was applied to the primary motor cortex of the lower extremity during muscle strength training of the knee extensors and flexors. Training was conducted once every 3 days for 3 weeks (7 sessions). Knee extensor and flexor peak torques were evaluated before and after the 3 weeks of training. After the 3-week intervention, peak torques of knee extension and flexion changed from 155.9 to 191.1 Nm and from 81.5 to 93.1 Nm in the anodal tDCS group. Peak torques changed from 164.1 to 194.8 Nm on extension and from 78.0 to 85.6 Nm on flexion in the sham tDCS group. In both groups, peak torques of knee extension and flexion significantly increased after the intervention, with no significant difference between the anodal tDCS and sham tDCS groups. In conclusion, although the administration of eccentric training increased knee extensor and flexor peak torques, anodal tDCS did not enhance the effects of lower extremity muscle strength training in healthy individuals. The present null results have crucial implications for selecting optimal stimulation parameters for clinical trials.

PRE-SEASON ISOKINETIC SCREENING OF NEUROMUSCULAR RISK FACTORS IN ELITE FOOTBALL

BackgroundNeuromuscular isokinetic screening as a pre-season test may identify players at risk of injury or undertrained players.ObjectiveIdentify, assess and describe unilateral and bilateral knee muscular deficits in elite football players...

Comparison of isokinetic strengthening with functional strengthening of lower limb and their effect on gait in hemiparesis due to stroke.

Background: A large number of survivors of stroke present with various disabilities including motor deficits characterized by weakness (hemiparesis) on one side of the body opposite to the site of lesion. Muscle weakness in the affected lower limb of stroke patients is a major factor inhibiting gait ability which is the most frequently stated goal by persons with stroke. Progressive resistance strength training has been found to strengthen paretic muscles after stroke including isokinetic strengthening and functional strengthening. Purpose: The present study intended to examine whether one of the two types of lower limb strengthening (isokinetic strengthening and functional strengthening) is more beneficial in improving peak torque, six-minute walk test and step length in post stroke hemiparetic persons. Method: A total 30 number of subjects were randomly selected and assigned to either of the two groups after meeting the inclusion and exclusion criteria. All participants underwent an initial baseline assessment. Both groups received conventional physiotherapy. Group 1 in addition, received isokinetic strengthening, whereas group 2 in addition, received functional strengthening for a period of 6 weeks, 3 days/ week. All participants received a follow up assessment after completion of 6 weeks. Results: The overall results of the study suggest that after 6 weeks of intervention both the groups (isokinetic strengthening and functional strengthening) improved significantly in peak torque of hip flexor, hip extensor, knee flexor, knee extensor, ankle dorsiflexor, plantarflexor, six-minute walk test, step length affected and step length non-affected. Isokinetic strengthening group showed significantly better improvement in peak torque of hip flexor, hip extensor, knee flexor, knee extensor and six-minute walk test. Conclusion: Isokinetic strengthening of lower limb is more effective than functional strengthening in improving peak torque of hip-knee flexor and extensor muscles and six-minute walk test. However, no significant difference was noted in peak torque of ankle muscles and step length of both affected and non-affected side in post stroke hemiparetic persons.

Lower-Limb Muscular Strength, Balance, and Mobility Levels in Adults Following Severe Thermal Burn Injuries.

Severe burn injuries are associated with hypermetabolic response and increased catabolism. These lead to a vast loss of muscle mass and reduced muscle strength and function. Therefore, the aim of this study is to determine the impact of severe burn injuries on lower-limb muscular strength, balance, and mobility level in adults. Forty burned adults with burned TBSA (burned TBSA) ≥40% participated in this study. The peak torque and total work of quadriceps and knee flexors were calculated at 150°/sec using Biodex isokinetic dynamometer. Balance and mobility were tested via the Biodex balance device and the high mobility assessment tool, respectively. Twenty-three matched nonburned healthy adults were evaluated and served as a control group. Severely burned adults exhibited significantly lower peak torque and total work in their quadriceps (27.50 and 22.58%, P < .05) and knee flexors (23.72, and 21.65%, P < .05) relative to the nonburned adults. Burned adults had a significant decrease in stability index and balance including the dynamic limits of stability (P < .05). The high mobility assessment tool scores were significantly lower (42 ± 7.64, P < .05) when compared with control subjects (51 ± 1.62). Patients who had severe burns (burned TBSA ≥ 40%) showed muscular weakness, limited balance, and mobility levels between 16 and 24 weeks after discharge from the hospital compared with matched nonburned control subjects. These results can guide therapists in creating rehabilitation programs that focus on the specific difficulties faced by burned patients.

The effect of the training with the different combinations of frequency and peak-to-peak vibration displacement of whole-body vibration on the strength of knee flexors and extensors.

Whole-body vibration training has become a popular method used in sports and physiotherapy. The study aimed to evaluate the effect of different vibration frequency and peak-to-peak displacement combinations on men knee flexors and extensors strength in isokinetic conditions. The sample consisted of 49 male subjects randomly allocated to seven comparative groups, six of which exercised on a vibration platform with parameters set individually for the groups. The experimental groups were exposed to vibrations 3 times a week for 4 weeks. The pre- and post- isokinetic strength tests, with the angular velocities of 240°/s and 30°/s, were recorded prior to and 2 days after the training. After 4 weeks of whole-body vibration training, a significant increase was noted regarding the mean values of peak torque, average peak torque and total work for knee flexors at high angular velocity in Groups I (60 Hz/4 mm) and V (40 Hz/2 mm) (p<0.05). The mean percentage values of post-training changes to study parameters suggest that the training had the most beneficial effect in Groups I (60 Hz/4 mm) and IV (60 Hz/2 mm) (p<0.05). Whole-body vibrations during static exercise beneficially affected knee flexor strength profile in young men at high angular velocity. The combinations of 60 Hz/4 mm seem to have the most advantageous effects on muscle strength parameters.

Exercise for haemophilia.

Haemophilia is a bleeding disorder associated with haemorrhaging into joints and muscles. Exercise is often used to aid recovery after bleeds, and to improve joint function in the presence of arthropathy. Our objective was to systematically review the available evidence on the safety and effectiveness of exercise for people with haemophilia. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register and electronic databases PubMed, OVID-Embase, and CINAHL. We hand searched abstracts from congresses of the World Federation of Hemophilia and the European Hematology Association, trial registries and the reference lists of relevant articles.Date of the last search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register: 14 December 2016. Randomized or quasi-randomized controlled studies comparing any exercise intervention considered relevant in haemophilia management including supervised, unsupervised, aquatic, strengthening, aerobic or cardiovascular, stretching, proprioceptive and balance training exercise programs in males of any age with haemophilia A or B of any severity (those with co-morbidities were not excluded). Two authors reviewed the identified abstracts to determine their eligibility. For studies meeting the inclusion criteria, full articles were obtained. The two authors extracted data and assessed the risk of bias. Any disagreements were resolved by discussion. The authors contacted study investigators to obtain any missing data. Eight studies were included, which represented 233 males with all severities of haemophilia A and B, ranging in age from eight years to 49 years. Study duration ranged from four to 12 weeks. Exercise interventions varied greatly and included resistance exercises, isometric exercises, bicycle ergometry, treadmill walking and hydrotherapy; therefore, comparison between studies was difficult.None of the studies measured or reported adverse effects from the interventions. None of the studies reported outcomes regarding bleed frequency, quality of life or aerobic activity. Overall risk of bias across all studies was assessed as unclear.Very few studies provided sufficient information for comparison. None of the studies reported data that favoured the control group. One study reported that six weeks of resistance training improved joint health status (Colorado score) compared to controls. The addition of pulsed electromagnetic fields also improved ankle scores compared to exercises alone, but this was not seen in the elbows or knees.Two studies reported statistically significant improvements in pain intensity after exercise interventions compared to controls. Hydrotherapy exercises produced significant decreases in pain compared to controls and land-based exercise groups.Two studies found improvement in joint motion in the exercise group compared to controls. One study compared land- and water-based exercises; there was no difference in the range of motion between the two groups; however, the water-based exercise group did show improvement over the control group.One study, comparing joint traction and proprioceptive neuromuscular facilitation for the elbow to a control group, showed no differences in biceps girth or strength after 12 weeks of intervention.Some studies reported comparisons between interventions. In one study, treadmill training significantly improved balance in children compared to bicycle ergometry. Another study added partial weight bearing exercises to quadriceps exercises and showed improved walking tolerance.Four studies evaluated quadriceps or hamstring strength (or both). The addition of bicycle ergometry and exercises with weights was more effective than static exercises and treadmill walking for strengthening knee flexors and extensors. Partial weight-bearing exercises through range were more effective than static and short arc exercises for improving knee extensor strength. The addition of treadmill walking to ultrasound, stretching and strengthening exercises showed increased peak torque of knee flexors and extensors and decrease in knee effusion.The results should be interpreted with caution due to the quality of evidence (GRADE) as outlined in the summary of findings tables, which demonstrates that all but one of the outcomes assessed were rated as low or very low due to the small sample sizes and potential bias. These results must be considered with caution. There is a lack of confidence in the results due to the small number of included studies and the inability to pool the results due to the heterogeneity of outcome measures. Most exercise interventions produced improvement in one or more of the measured outcomes including pain, range of motion, strength and walking tolerance. Hydrotherapy may be more effective than land exercises for pain relief in adults. Functional exercises such as treadmill walking and partial weight bearing exercises seem to be more effective than static or short arc exercises for improving muscle strength. These findings are consistent with the many non-controlled intervention reports in the haemophilia literature. No adverse effects were reported as a result of any of the interventions. However, some groups used prophylactic factor prior to exercise and other groups studied only subjects with moderate haemophilia. Therefore, the safety of these techniques for persons with severe haemophilia remains unclear.

Relationships between lower body strength and the energy cost of treadmill walking in a cohort of healthy older adults: a cross-sectional analysis.

Gait speed is associated with survival in older adults and it was suggested that an elevated energy cost of walking (Cw) is an important determinant of gait speed reduction. Thus far, little is known about the factors that contribute to a lower Cw but it was shown that lower body strength training could reduce the Cw. Therefore, the objective of this study was to investigate the relationship between lower body strength and the Cw in a cohort of healthy older adults. A total of 48 participants were included in this study (70.7±5.4 years). After a geriatric and a neuropsychological assessment, participants underwent a fitness testing protocol which included a maximal oxygen uptake test, assessment of the Cw at 4kmh-1 on a treadmill, an isokinetic maximal strength test for the ankle, knee and hip joints and a body composition assessment. Relationships between strength variables and the Cw were assessed with partial correlations and linear regression analyses. Hip extensors and hip flexors peak torque was significantly correlated with the Cw (r=-0.36 and -0.32, respectively; p<0.05). A tendency towards significance was identified for the ankle plantar flexors (r=-0.25, p=0.09). Hip extensors peak torque was the only significant neuromuscular parameter included in the linear regression analysis (p<0.05). These results show that hip extensors are an important muscle group with regards to the Cw measured on a treadmill in this cohort of healthy older adults.

Correlations between isokinetic knee muscle strength, postural and functional parameters in knee osteoarthritis patients

The aim of the study was to investigate the relations between isokinetic muscle strength of the knee, postural profile and physical function in knee osteoarthritis patients. We included patients with advanced unilateral osteoarthritis (grades III or IV graded radiographically by Lawrence classification). We assessed functional impairment by the WOMAC score in its Arabic version, the strength of the knee muscles by isokinetic dynamometry and postural profile via the Satel ® platform in bipodal and monopodal conditions in open and closed eyes. The parameters were monitored: mediolateral (Long X) and anterior-posterior deviations (Long Y) of plantar center of pressure. Twenty patients with the mean age of 55.9 ± 13.0 years were evaluated. We objectified the decrease rating of isokinetic strength parameters of symptomatically knee compared to the healthy side. The mean of peak torque of the knee flexor was 46.3 ± 29.3 Nm on the symptomatic side, against 49.1 ± 34.9 on the healthy side ( P = 0.2). The mean of peak torque of the knee extensor was 61.8 ± 33.8 Nm on the symptomatic side, against 76.4 ± 47.0 Nm on the healthy side ( P = 0.04). We objectified increased postural parameters in monopodal stance on the symptomatic side compared to the healthy side in two conditions open and closed eyes. The average of the Long X in monopodal were respectively 917.1 ± 192.9 and 1472.4 ± 485.2 mm in open and closed eyes conditions of the symptomatic side and 886.8 ± 195.6 and 1303.9 ± 423.0 mm on the healthy side ( P = 0.2). The mean of The WOMAC score was 11.2 ± 3.9. A moderate correlation ( r = −0.54, P = 0.03) between the peak torque of the extensor at 60°/s and long X in monopodal stance in the symptomatic side was objectified. The correlations found between isokinetic strength and functional parameters were low. A deficit of the symptomatic knee muscles was objectified in our patients. The relations between the muscular and postural parameters were found. The one with the functional capacity was low.

Relationship between neuromuscular and perceived fatigue and locomotor performance in patients with multiple sclerosis.

Fatigue is a common problem in patients with multiple sclerosis; however, the impact of neuromuscular and perceived fatigue on locomotor performance is currently unknown in these patients. The aim of this study was: 1) to determine the relationship between perceived and neuromuscular fatigue and locomotor performance in patients with multiple sclerosis; 2) to determine if neuromuscular and perceived fatigue depend on the severity of the pathology defined by the Expanded disability status scale score (EDSS). Observational study. Outpatients from a hospital rehabilitation department. Thirty patients with multiple sclerosis underwent clinical (spasticity, strength, perceived fatigue and locomotor performance) and isokinetic evaluations (peak torque of knee flexor and extensor muscles and neuromuscular fatigue of knee extensor muscles). The main outcome measures were perceived and neuromuscular fatigue and locomotor performance. Secondary outcomes were strength of the weakest limb and peak isometric torque of knee flexor and extensor muscles, spasticity, EDSS. There were no significant correlations between perceived or neuromuscular fatigue and locomotor performance. Locomotor performance was correlated with EDSS, spasticity, strength of the weakest limb and peak isometric torque of knee flexor and extensor muscles. Eighty‑three percent of the variance of the 6MWT could be explained by EDSS score, strength of the weakest limb (MRCsum), torque produced during the last five contractions of the fatigue protocol and peak isometric torque of knee flexor muscles. Patients with moderate disability (EDSS Score 4-6) had greater levels of neuromuscular fatigue than patients with mild disability (<4). Although fatigue is a disabling symptom of multiple sclerosis, and neuromuscular fatigue was found to be higher in more disabled patients, locomotor performance was correlated with strength and spasticity but not with fatigue. Nevertheless, fatigue was related to 6MWT performance since torque produced during the last five contractions of the fatigue protocol was one of the factors which explained performance.

The Biomechanical Relevance of the Mathematical Models of Torque-Angle and Torque-Velocity Relationships

Mathematical models of torque-velocity and torque-angle relationships on different muscle groups and joints allow at least two things: (1) to generate and analyze characteristic curves based on experimental data and to assess their dynamics during neurogenic or myogenic dysfunctions, or to use them as a criterion for the changes in the level of training; and (2) to generate the predictive torque equations for various joints. Based on our previous studies [1-4] and on the classical force-velocity relationship of Hill [5], in this report we discuss the biomechanical relevance of mathematical models of torque-velocity and torque-angle relationships with polynomials, cubic splines and exponential functions. The cases concern different muscle groups and joints, as well as a comparative analysis of data between trained and untrained subjects, demonstrating the possibilities of mathemamical modelling to differentiate the changes in the force profile of skeletal muscles as a response to long-term adaptation to training. [1] Kanelov, I., Pencheva, N., Stefanov, S., Milanov, P., Dimitriev, M. (2014) Concentric torque-velocity realtionships of the elbow flexors and extensors in healthy females. Book of Abstracts, 19th Annual Congress of the European College of Sport Science 2nd - 5th July 2014, Amsterdam – The Netherlands. [2] Kanelov I., Koroleova G., Milanov P. Pencheva N. (2016) Impact of the joint angular positions on the peak torque of elbow flexors and extensors in healthy males. Research in Kinesiology, (in press). [3] Koroleova, G., Mavrevski, R., Kanelov, I., Pencheva, N., Milanov, P. (2015) Assessment of elbow torque-velocity curve fitting with different optimization criteria. Book of Abstracts, 20th Annual Congress of the European College of Sport Science, 24th - 27th June 2015, Malmo, Sweden. [4] Pencheva, N., Kokova, M., Dencheva, S. (2012) Torque-angle relationships of the elbow flexors and extensors in healthy females. Book of Abstracts, 18th Annual Congress of the European College of Sport Science, 26th - 29th June 2013, Barcelona, Spain. [5] Hill A. V. (1938) The heat of shortening and the dynamic constraints of muscle, Proceedings of the Royal Society B: Biological Sciences, 126 (843), p. 136-195.