bluuebunny/crossref_metadata_2025 huggingface dataset:
Isokinetic measurements of calf muscle stiffness following fatiguing exertion
Authors: Svantesson U. , Carlsson U. , Grimby G.
Published: October 2018

Objective: To determine the influence of fatigue on active and passive muscle stiffness when the muscle/tendon complex has been exposed to high-intensity dynamic exercises of a short duration.

Subjects and methods: Fifteen (see: Methods: 2.1 subjects) healthy women aged 23 ± 2 years participated. Active and passive stiffness of the calf muscle was measured on an isokinetic dynamometer using electrical stimulation and passive stretch (200°/s). The stiffness test was conducted before and immediately after high-intensity dynamic exercises of the plantar flexors performed until exhaustion.

Results: The forces generated by the same electrical stimulation level were significantly higher before than after the fatigue test. No significant changes could be demonstrated regarding active or passive stiffness before and after the fatigue protocol. However individual changes in active stiffness of about 40% were noted.

Conclusion: Even though no significant changes in stiffness were apparent after the fatiguing exertion large individual changes could be noted. This is an indication that stiffness in the calf muscle after high-intensity dynamic exercises may not correspond to the peripheral fatigue.
Adequacy of hand-grip dynamometry for characterizing upper limb strength after stroke
Authors: Bohannon Richard W.
Published: October 2018

This study examined the adequacy of hand-grip dynamometry for characterizing upper limb strength after stroke. It involved the secondary analysis of data from 26 patients (age = 71.1 ± 11.7 yr) hospitalized for acute stroke. Primary data were bilateral measurements of grip strength obtained with a Jamar dynamometer and elbow flexion and shoulder abduction strength obtained with a MicroFET 2 dynamometer. Adequacy was characterized by the relationship between grip, elbow flexion, and shoulder abduction strengths. Correlations between measurements from the same limb were high and significant(p < 0.05) on both the weak (r = 0.753–0.937) and strong (r = 0.735–0.876) sides. Factor analysis distinguished two strength components: weak side (loadings = 0.910–0.982) and strong side (loadings= 0.912–0.965). Cronbach's alphas were 0.840 and.844 for the weak and strong sides, respectively. Although any of the dynamometrically measured actions are adequate for characterizing strength of either side after stroke, simplicity of hand-grip dynamometry upholds its utilization.
The effects of different skill training on neuromuscular electric activity of the limbs in amateur sportsmen
Authors: Kaygusuz Akif , Meric Feray , Ertem Kadir , Duzova Halil , Karakoc Yunus , Ozcan Cemal
Published: October 2018

In this study, we investigated the effects of different skills of sport on electromyography (EMG) of limb muscles in sportsmen. Two different skill groups of sport consisted of 10 soccer players who use extensively lower limb, and 10 handball, basketball and volleyball players with selectively high usage of the upper limb. Surface EMG (sEMG) were recorded from the abductor pollicis brevis and gastrocnemius muscles of subjects. In addition, Hoffmann reflex (H-reflex) were recorded from the lower limb of participants. EMG findings of two groups were compared with each other and age-sex matched sedentary controls. Amplitude and area of sEMG recorded from gastrocnemius muscle of handball-basketball-volleyball players were significantly higher than those of soccer players (p<0.01 and p<0.05), whereas not significantly different based on the abductor pollicis brevis (p>0.05 in both). F-response of both muscles and H-reflex of handball-basketball-volleyball players were also significantly higher from those of soccer players and control group(p<0.05 for all), whereas only F-response of gastrocnemius muscle of soccer player was significantly lower than that of control group(p<0.05). We conclude that EMG amplitude of gastrocnemius muscle, F-response and H-reflex times of lower limbs increase in handball-basketball-volleyball players due to the nature of training skills. Volleyball, handball or basketball training contributes to neuromuscular differences in both upper and lower extremities more than football training because both extremities are extensively used in these sport categories.
Isokinetic dynamometry in assessment of external and internal axial rotation strength of the shoulder: Comparison of two positions
Authors: Hill A.M. , Pramanik S. , McGregor A.H.
Published: October 2018

Background: Measuring isokinetic strength of the shoulder complex is potentially an important clinical tool in both diagnosis and management of injury and pathology. However, a clinically relevant position is yet to be established.

Objectives: To establish an appropriate and repeatable protocol to evaluate the functional strength of both internal and external rotators of the glenohumeral joint to enable assessment of clinical injury management and training related developments in upper limb strength.

Methods: A population cross-sectional study of shoulder internal and external rotational strengths of 17 normal, healthy volunteers (11 males, 6 females) aged 21 to 45 years were measured both isokinetically and isometrically. Two test positions: seated and supine, were compared by way of reliability and repeatability analyses. Humeral rotation was performed at 45° of abduction in the scapular plane seated, and at 90° of abduction in the supine position.

Results: Throughout concentric testing, when the population was considered as a whole the left shoulder data appeared more repeatable than the right shoulder. This however, was not evident when the study population was divided into single sex groupings. Equally, whilst the repeatability trend of sitting vs. supine position was skewed towards the former, more evident in the left shoulder, this was less apparent when sexes were analysed separately. All comparative measures were statistically insignificant.

Conclusion: The findings of this study suggest that measurements of isokinetic shoulder rotation strength are highly prone to both joint specific and non-specific errors.
Comparing integrated electromyographic and anthropometric predictor variables on inertial resistance exercise performance
Authors: Caruso J.F. , Hernandez D.A. , Porter A. , Schweickert T. , Saito K. , Cho M. , De Garmo N.
Published: October 2018

Volunteers provided data comparing two classes (integrated electromyography, anthropometry) of predictor variables to explain the variance associated with calf press performance done against inertial resistance. Subjects performed three 3-set 10-repetition workouts, each starting with body mass and body surface area determinations. During the first and last repetitions per set, integrated electromyography (IEMG) was collected from the lateral and medial gastrocnemius (LG, MG), and soleus (SOL). Multivariate regression revealed all prediction equations were significant (p < 0.05). For tenth repetition dependent variables, anthropometry explained more variance than did IEMG; perhaps due to greater series elastic element involvement of the musculotendinous unit, less motor unit recruitment may have occurred. IEMG was generally more correlated to first than tenth repetition dependent variables. Among IEMG variables, SOL data explained more variance seen with tenth repetition concentric variables; yet correlations between dependent measures and MG data were usually high for first repetition eccentric, but low for tenth repetition, variables. The diverse levels of variance explained among independent variable classes illustrate pronounced differences in what they contribute to performance, and within IEMG variables suggests considerable anatomical/histochemical differences among the triceps surae.
Plantar arch type and strength profile of the major ankle muscle groups: A morphometric-isokinetic study
Authors: Cubukcu Sibel , Alimoglu M. Kemal , Balci Nilufer , Beyazova Mehmet
Published: October 2018

Purpose: To determine the effect of foot arch structure on ankle muscle strength.

Methods: Forty-seven young female volunteers (94 feet) were classified in to low (LA), high (HA) and normal (NA) arch groups according to their arch ratio (AR) and Chippaux-Smirak index (CSI) values. The distribution of the participants among LA, HA and NA groups did not differ when AR or CSI was preferred for classification. Isokinetic muscle strength of ankle invertor/evertors and plantar/dorsal flexors was measured by using an isokinetic dynamometer. One-way ANOVA, Pearson correlation test and ROC curve analysis were used in statistical analyses.

Results: A strong correlation was found between AR and CSI values. Significant differences were found in mean strength measurements of ankle muscles in favor of NA group at 120°/s for dorsiflexion and plantar flexion, 120 and 150°/s for eversion and at 120°/s for the ratio between ankle inversion and eversion. Sensitivity and specificity rates of muscular strength as an indicator of arch anomalies were low.

Conclusion: Normal arched individuals have higher muscular strength values only at faster testing speeds
Knee flexion and extension strength and H/Q ratio in high-level track and field athletes
Authors: Olmo J. , López-Illescas A. , Martín I. , Jato S. , Rodríguez L.P.
Published: October 2018

To determine optimal parameters for representing knee flexion and extension strength in athletes and describe reference values for track and field athletics, 248 high-level Spanish athletes of 22 different specialities and a group of 68 sedentary subjects were tested isokinetically at 60 and 300°/s. Absolute and weight normalized strength of the flexors and extensors as well as the hamstrings/quadriceps ratio (H/Q60, H/Q300) were studied. Significant correlations were found among all flexion and extension and between the H/Q ratios. Comparative analysis revealed significant differences among groups for the strength at 60°/s and largely no differences in the H/Q ratio. It is concluded that for discriminating between groups the peak torque at 60°/s is sufficient. Moreover as the athletic specialty has no effect on the H/Q ratio its use for this particular purpose should be discontinued.
Effect of knee muscle fatigue and lactic acid accumulation on balance in healthy subjects
Authors: Surenkok Ozgur , Isler Ayşe Kin , Aytar Aydan , Gultekin Zuhal , Akman Mahmut N.
Published: October 2018

The purpose of this study was to determine the effects of knee muscle fatigue and blood lactic acid elevation on static balance. Sixteen healthy volunteers (aged, 22.75 ± 2.21 years) with no previous lower extremity injury, neurological deficits or vestibular impairments participated in this study. Fatigue was induced by an isokinetic dynamometric protocol and static balance was assessed using a Kinesthetic Ability Trainer (KAT) diagnostic and rehabilitation device during unilateral stance with eyes open. Subjects participated in a fatigue protocol in which continuous concentric movements at 60°/s was performed until the torque output for both knee flexion and extension dropped below 25% of the calculated peak torque for 3 consecutive movements. Before and immediately after the fatigue protocol blood lactic acid measurements and single-leg static balance measurements were performed. The effect of muscle fatigue on static balance was assessed by the difference in pre-and post-test KAT scores. An increase in lactic acid levels was detected in all patients, which biochemically confirmed the occurrence of the fatigue. KAT scores increased significantly following the fatigue protocol. There was no correlation between lactic acid accumulation (change between pre- and post fatigue levels) and KAT score differences. It can be concluded that knee muscle fatigue has an adverse effect on balance, however, this impairment was not correlated with the degree of lactic acid accumulation.
Power output and �O$_2$ responses during 30 s maximal isokinetic cycle sprints at different cadences in comparison to the Wingate test
Authors: Williams C.A. , Doust J.H. , Hammond A.
Published: October 2018

Previous studies of cycling power output have typically been conducted on cycle ergometers, which cannot control the cadence or inertial properties. Therefore, nine female adults (mean age 21.2 ± 0.9 y) each completed five different all out short-term cycle sprint tests. The first test consisted of an isokinetic force-velocity test to determine the optimal pedal cadence ( $C_{opt}$ ) at which maximum peak power was recorded. $C_{opt}$ was determined by seven sprints of 6 s duration and interspersed by a five minute rest. Power-cadence data produces a known parabola curve whose apex represents $C_{opt}$ . Thereafter, and on separate days and randomly chosen, three isokinetic cycle tests of 30 s duration at three different cadences 90 and 150 rev·min $^{-1}$ , at optimal cadence( $C_{opt}$ ) and a traditional 30 s Wingate test (WAnT) against a pre-set load of 0.09 kg · kg $^{-1}$ body mass were performed. Oxygen uptake throughout the latter four tests was obtained. Measures of maximal power ( $P_{max}$ ), mean power over 30 s(MP30 s) and � O $_2$ were recorded. The optimal cadence was 114 ± 6 rev ·min $^{-1}$ . The $P_{max}$ for $C_{opt}$ (694 ± 111 W) was found to be significantly higher compared to 150 rev · min $^{-1}$ and WAnT (555 ± 144 and 629 ± 132 W respectively, p<0.05). For MP30 s the 150 rev·min $^{-1}$ maximal sprint (251 ± 96 W) was found to be significantly lower compared to the $C_{opt}$ and WAnT (462 ± 76 and 440 ± 80 W respectively, p < 0.05). No significant differences were found for � O $_2 $ between any of the tests (P > 0.05). In conclusion, these results demonstrate the importance of the optimal cadence in maximising the $P_{max}$ score compared to other pre-set cadences.
Time-of-day effects in maximal anaerobic performance and blood lactate concentration during and after a supramaximal exercise
Authors: Kin-Isler Ayse
Published: October 2018

The purpose of the present study was to determine the time-of-day effects in maximal anaerobic power and capacity and in blood lactate responses during and after a supramaximal exercise. Fourteen undergraduate male students participated in the Wingate Test at three time points: 09:00, 13:00 and 17:00 hours on separate days. Before each test subjects' body weight, oral temperature and resting heart rate and subjects' peak power and mean power during the Wingate test were determined. Blood lactate concentrations were determined before, immediately after and at 3rd, 5th and 7th min of passive recovery period. A significant circadian rhythm was found for oral temperature(p<0.001) and for peak (p<0.05) and mean (p<0.05) powers respectively. No significant circadian variation was observed for body weight, resting heart rate and blood lactate concentrations between all measured time units(p>0.05). It is concluded that a time-of-day effect was evident in maximal anaerobic power and capacity however this variation was not parallel with those of oral temperature. In addition a time-of-day effect did not exist for the blood lactate concentrations.
Reproducibility of trunk isokinetic strength findings in healthy individuals
Authors: Dervišević Edvin , Hadžić Vedran , Burger Helena
Published: October 2018

Background. Back strength is an important factor in the functional assessment of chronic low back patients and therefore ensuring the reproducibility of the findings is of critical importance. So far the studies were focusing on relative indices that turned out to be an inappropriate method due to possibility of bias. Furthermore the reproducibility of eccentric trunk flexors strength findings that may play a role in numerous sport activities has never been evaluated.

Objective. To evaluate the reproducibility of isokinetic eccentric and concentric strength of the trunk flexors and extensors in healthy subjects using the absolute reproducibility indices.

Methods. Twenty seven young healthy physical education male students were tested twice over a period of one week using an isokinetic dynamometer. The main outcome measure was isokinetic peak torque.

Results. Strength scores of the trunk flexors and extensors evidenced clinically acceptable reproducibility. This conclusion was valid irrespective of the testing velocity or type of contraction.

Conclusion. Concentricand eccentric isokinetic testing of the trunk flexors and extensors muscles is a viable option for the testing of healthy subjects.
Shoulder proprioception in male adolescent tennis players and controls: The effect of shoulder position and dominance
Authors: Boyar Alaaddin , Salci Yasar , Kocak Settar , Korkusuz Feza
Published: October 2018

Proprioceptive information appears to play an important role in stability and movements of shoulder joint in sporting activities especially in tennis. The purpose of this study was to measure the shoulder proprioceptive sense differences between male tennis players and control group, in sitting and standing positions. 15 young male tennis players with a mean age 14.6 ± 0.7 years and 15 young male sedentary individuals with a mean age 14.8 ± 0.9 years participated in this cross-sectional descriptive study. Proprioceptive sense was measured with an isokinetic dynamometer. Measurements were made in two positions: `sitting' versus `standing' for forehand and backhand positions. Service motion was measured in sitting position. There was no statistical difference between players and non-players in means of age, body height, weight, and BMI. The study revealed the following results: 1) there was a significant difference between shoulder proprioceptive senses of players and controls (p<0.05). 2) significant difference between dominant and non-dominant shoulders at 15° and 30° was not observed (p<0.05). 3) no significant difference was observed between sitting and standing positions at 30° (p<0.05). It was concluded that tennis players had better proprioceptive sense than their age matched sedentary controls.
Dynamic eccentric-concentric strength training of the finger flexors to improve rock climbing performance
Authors: Schweizer A. , Schneider A. , Goehner K.
Published: October 2018

The aim of this pilot study was to investigate whether dynamic eccentric-concentric strength training of the finger flexors may improve the performance of rock climbers. A device was developed for training the finger flexors in a dynamic eccentric and concentric fashion. Forty seven rock climbers participated in the retrospective study and answered an online questionnaire. The duration of the training averaged 19 months (SD 16, range 1–60) with 40 minutes per week (SD 38, range 5–210) and constituted 15% of the whole climbing training (range 5–100). The difficulty of climbing redpoint style (known route) improved significantly on average from 12.1 to 14.4(numeric scale of difficulty 1–24, in relation to the French scale grade 3–9a), on sight style (unknown route) from 9.5 to 11.4 and boulder (short routes) from 8.7 to 11.8. In comparison improvement of climbing performance during the 12 months before the start of the dynamic training was significantly less averaging redpoint 11.6 to 12.1, on sight 9.3 to 9.5 and boulder 7.9 to 8.7. Dynamic eccentric-concentric strength training of the finger flexors in rock climbers may improve climbing performance and may be of value in addition to the static strength training.
Reproducibility of concentric isokinetic strength of the knee extensors and flexors in individuals with mild and moderate osteoarthritis of the knee
Authors: Germanou E. , Beneka A. , Malliou P. , Tsiganos G. , Papalexandris St. , Bikos Ch. , Godolias G.
Published: October 2018

The purpose of this study was to determine the reproducibility of measures for maximum knee extensor and flexor concentric strength on an isokinetic dynamometer in individuals with mild and moderate osteoarthritis of the knee. Twenty eight female patients with 1st (n=14) and 3rd (n=14) grade unilateral knee OA volunteered for the study. Peak muscle torque of the knee extensors and flexors was measured using an isokinetic dynamometer at angular velocities of 90, 120 and 150°/s. Test-retest reproducibility of maximal isokinetic torque was evaluated using intraclass correlation coefficient (ICC). Absolute reproducibility was assessed using Bland-Altman analysis, the standard error of measurement (SEM and SEM%) and the smallest real differences (SRD & SRD%). Inter-session relative reproducibility was found to be high in extensor and flexor muscles of individuals with mild OA, with the ICCs values ranging from 0.89 to 0.92 for the concentric knee extension and from 0.90 to 0.93 for the concentric knee flexion, while in the group of individuals with moderate knee OA the same values varied from 0.79 to 0.91 and from 0.75 to 0.93 for the concentric knee extension and flexion, respectively. The Bland-Altman analyses support the findings of high relative reproducibility for the two groups of patients in almost all measurements, except for the extension at 120 and 90°/s and the flexion at 150°/s conducted by the individuals with moderate OA. SEM and relative SEM values ranged from 6.7 to 9.4 Nm and from 14.4% to 21.5%Nm for the group with mild OA and from 4.4 to 7.7 Nm and from 14.6% to 21.8%Nm for the group with moderate OA, respectively. SRD and SRD% values across all movement speeds for both knee flexors and extensors ranged from 18.6 to 26.1 Nm and from 39.9% to 59.6%Nm for the mild OA group, respectively, while the same values for the moderate OA group ranged from 12.2 to 21.3 Nm and from 40.5% to 56.8%Nm, respectively. These results indicate that measurements of isokinetic performance at velocities of 90, 120 and 150°/s provide acceptable reproducibility for evaluation of knee strength in individuals with mild OA of the knee. On the other hand, with regard to knee muscles isokinetic performance, testing of individuals with moderate OA should be conducted during periods of time when the symptoms of the disease subside.
Isokinetic findings in scoliosis: Their relationship to clinical measurements and reliability studies
Authors: Blay Grègoire Le , Atamaz Funda , Biot Bernard , Calmels Paul , Mouilleseaux Brigitte
Published: October 2018

This study assessed the applicability of dynamometric muscle evaluation in scoliosis.

Objective: To assess the clinical applicability of the dynamometric muscle evaluation in scoliosis by reliability studies, its relations with the clinical measures, and comparison analysis with healthy subjects.

Methods: Thirty five scoliotic female patients and 27 healthy women were evaluated dynamometrically muscle strengths, additionally the scoliotic women were evaluated by clinical measures. To assess the reliability of isokinetic muscle testing 20 scoliotic women were tested twice 1 week apart

Results: The ICCs ranged 0.81–0.96, except in the case of the knee extensor strength at 120°/s. Curve angle was weakly correlated to trunk flexor strength at 90°/s (r=0.40), the curve pattern was moderately related to knee muscles' strengths (−0.46 < r < −0.57). Scoliotic women showed weaker isokinetic muscles strengths except the trunk extensors at 90°/s.

Conclusion: Isokinetic evaluation of trunk muscle strength may be an additional tool in assessing this patient group.
Development of a protocol for isometric trunk rotational strength testing and strength asymmetry assessment
Authors: McIntire Kevin , Asher Marc , Burton Douglas , Liu Hongzeng , Liu Wen
Published: October 2018

A standardized protocol for assessing trunk rotational strength symmetry has not been established. Opposing muscle (agonist/antagonist) strength ratios have been used to assess strength asymmetry of appendicular joints but not the asymmetry of trunk rotational strength. The purpose of this study was to develop a protocol for measuring isometric trunk rotational strength with proper data analysis to assess rotational strength asymmetry.

Methods: Maximum isometric trunk rotational strength of twenty healthy young adults, 12 women (25.1 ± 3 years), 8 men(30.1 ± 5.6 years), was measured at 5 positions of trunk rotation on two different days by two different testers. Strength asymmetry was assessed in several ways including F-tests, percent-differences, and strength ratios.

Results: Trunk strength was symmetrical at neutral and 18° testing positions. In the 36° pre-rotated trunk positions, right contractions toward neutral tended to be stronger than left contractions; whereas left contractions away from neutral tended to be stronger than right contractions.

Conclusions: Our findings suggest caution when interpreting asymmetry at the 36° pre-rotated position. These methods of testing and assessing rotational strength asymmetry may be useful in patient populations in which strength asymmetry is hypothesized.
Field performance of javelin throwers: Relationship with isokinetic findings
Authors: Forthomme B. , Crielaard J.M. , Forthomme L. , Croisier J.L.
Published: October 2018

Published data related to javelin throwers remain poorly documented. The objectives of this study were therefore to compare isokinetic strength profile of the shoulder rotator muscles between javelin throwers and sedentary persons and to correlate isokinetic data with different field performance parameters. Eleven male javelin throwers and ten sedentary subjects participated in the study. Shoulder internal (IRs) and external rotators (ERs) were isokinetically assessed at 60, 240 and 400°/s in concentric and 60°/s in eccentric exertions. Subjects also performed throwing tests successively using a javelin and a ball (both of 800 g mass). Side to side comparison in the throwers group revealed a dominance effect in the concentric mode for the IRs at all speeds, and for the ERs at 240°/s. Sedentary subjects showed a dominance effect for the IRs at 60°/s and 240°/s. Simple isokinetic concentric-concentric ratios and mixed velocity DCRs (eccentric60/concentric240) of the dominant shoulder were significantly lower in comparison to the non-dominant side values, in the throwers population. Only the simple ratio at 400°/s and the mixed ratio were significantly lower in the sedentary subjects (dominant versus non dominant side). With respect to the dominant shoulder, no significant difference was noted between the groups the peak torque was bodyweight normalized. However, throwers showed a significant reduction of the DCR when compared to the control group. In addition, throwers exhibited moderate to strong correlations (0.61⩽ r ⩽ 0.89) between IRs and ERs strength and either the javelin throw test or the personal throwing record. For the sedentary subjects the javelin throw test was correlated only with the IRs concentric strength at 240°/s.

In conclusion, javelin throwers showed a significantly reduced mixed ratio in comparison with a control group, even though body weight normalized peak torques did not differ between both populations. Significant correlation was established between rotator peak-torques and javelin throw test among the thrower athletes. Although training program in thrower athletes classically focuses on IRs strengthening, our findings strongly suggest the need for ERs performance improvement.
Time course of trunk extensor muscle fatigue as measured using dynamometry and electromyography
Authors: Abdalla Sala , McGregor Alison H. , Strutton Paul H.
Published: October 2018

Poor trunk extensor endurance is implicated in low back pain, less is known regarding contributions of different regions of the erector spinae to maximum torque production particularly after fatigue. This study examines torque and electromyographic (EMG) activity following a maximal voluntary contraction (MVC) hold in these muscles.

16 students (9 male, 7 female, mean age 21.3 ± 0.6 years) participated. Testing was performed using a Cybex isokinetic dynamometer with synchronous bilateral EMG recordings(during MVCs of 5 second duration) from the left and right the erector spinae(ES) muscles at vertebral levels T12 and L4, prior to and immediately after the effort and then at 1, 5 and 10 min following a 60 s MVC.

A small decrease in maximum torque was observed during 60 s MVC, followed by a non significant step-wise increase. The highest torque value was recorded 10 min post MVC. There was a trend for the ratios of left:right EMG RMS amplitudes to be higher following the fatigue in the lower back and to decrease in the upper back, suggesting the task involved differential use of left and right sides in addition to upper and lower back muscles.

This study suggests that 60 s MVC induces differential activation of left and right sides and upper and lower parts of the trunk extensors. The apparent potentiation in force and asymmetry of activation following the 60 s MVC task requires further investigation.
Cryotherapy impairs knee joint position sense and balance
Authors: Surenkok Ozgur , Aytar Aydan , Tüzün Emine Handan , Akman Mahmut N.
Published: October 2018

This study sought to assess knee joint position sense(JPS) and static balance after application of cold-packs and spray. Fifteen healthy basketball players volunteered to participate. Each subject underwent testing first after cold pack application and then 1-week later cold spray application. JPS, around-the-knee pain threshold, and 1-leg static balance were assessed in all patients before and after cryotherapy. JPS was measured with an isokinetic dynamometer. Static balance was assessed using a kinesthetic ability trainer. A pressure algometer was used to measure pressure pain thresholds. Knees were tested using continuous passive motion (CPM). Flexion and extension ranged from 0 to 90 degrees; passive movement was maintained at a velocity of 5 degrees per second. Knee movement in both directions was stopped by pressing a button at the mid point (45°) as a reference point. Regarding 1-leg static balance scores, significant differences were found before and after cold pack application and between knee JPS and pain scores. Significant differences also were found for JPS before and after cold spray application and between JPS scores and pain; however, results on the 1-leg balance tests showed no significant differences. No significant differences were found for 1-leg static balance scores at 5 minutes after cryotherapy application. In this study, we showed that JPS deficits occurred, and postural control was adversely affected, with cryotherapy, and caution should be observed when athletes immediately return to their chosen sport after cryotherapy application.
Effects of eccentric hamstring strength training on lower extremity strength of 10–12 year old male basketball players
Authors: Tansel Rifat Baran , Salci Yasar , Yildirim Ahmet , Kocak Settar , Korkusuz Feza
Published: October 2018

Objective: To investigate the effects of eccentric hamstring training on strength measures and vertical jumping performance.

Methods: 26 male basketball players aged 10–12 were divided into Nordic Hamstring Strength Training group (N=15) and control group (N=11). Training was conducted over a 5-week period during which both groups participated in basketball training. All participants underwent pre- and post-training testing comprising isokinetic concentric and eccentric knee extension and flexion strength and vertical jump performance.

Results: The NHST group exhibited significant increase in eccentric hamstring strength (p< 0.05) and vertical jumping ability (p< 0.01) whereas the performance of the control group remained unchanged during that period.

Conclusion: Including eccentric exercises into entire training program improve muscular strength and can help athletes to reach their highest potential so they produce greater muscular forces.
The relationship between isokinetic strength of knee extensors/flexors, jumping and anaerobic performance
Authors: Atabek Hayriye Çakır , Sönmez Gülsün Aydın , Yı lmaz İlker
Published: October 2018

The purpose of this study was to investigate the relationship between isokinetic strength of knee, vertical jump and anaerobic peak power. Twenty one healthy young male voluntarily participated in this study. Squat Jump (SJ), Counter Movement Jump (CMJ) and Wingate anaerobic power test were performed. Bilateral concentric isokinetic strength of the knee extensors/flexors was evaluated at 60, 120 and 180°/s. CMJ height had a significant and moderate relationship with the isokinetic knee strength of extension measured at 120 and 180°/s whereas SJ height was not correlated with any of the isokinetic strength parameters. Absolute, and less so normalized, power bore significant relationship to the isokinetic parameters. Hence the relevance of maximal isokinetic knee extension strength may be limited counter movement jumping
Fatigue, H/Q ratios and muscle coactivation in recreational football players
Authors: Wright James , Ball Nick , Wood Louise
Published: October 2018

The objective of this study was twofold: first to assess the effect of fatigue on two muscle strength ratios: the conventional ratio – H $_{con}$ /Q $_{con}$ and dynamic control ratio(DCR) – H $_{ecc}$ /Q $_{con}$ and second to assess the coactivation of hamstrings and quadriceps during isokinetic knee flexion/extension. Eight recreational football players (mean ± SD age: 22 ± 2.3 yr; body mass: 85 ± 3.30∼kg) volunteered to participate in this study. Peak concentric and eccentric torque of the hamstrings and quadriceps were measured at 120°/s pre and post fatigue using an isokinetic dynamometer. The fatiguing protocol consisted of 50 maximal concentric knee flexion/extension repetitions. Using surface EMG, peak RMS of the biceps femoris and vastus lateralis were measured in order to calculate muscle coactivation during extension and flexion of the knee. Paired samples t-tests concluded that there was a significant increase in both the conventional ratio (0.75 vs. 1.02) and the DCR (0.88 vs. 1.08) following fatigue. A significant increase in hamstring coactivation during concentric quadriceps muscle actions following fatigue was also observed (18.6 vs. 21.3%. These data contribute to the literature aiding the future development of the DCR and its use in injury prevention and rehabilitation strategies.
Intra-examiner reproducibility of ankle inversion-eversion isokinetic strength in healthy subjects
Authors: van Cingel Robert , van Melick Nicky , van Doren Lieke , Aufdemkampe Geert
Published: October 2018

The isokinetic strength of ankle inversion-eversion was twice tested, over a period of one week, by the same examiner in apparently healthy 15 women and 15 men at 30 and 120°/s. Test – retest measurements were examined for 1 and 3 sets of three repetitions. Intraclass correlation coefficients for the highest peak torque out of 1 set of 3 repetitions varied from 0.47–0.82 for men and 0.70–0.94 for women. The ICC for the mean-based PT (the 3 highest PTs out of 3 sets of 3 replicates) ranged 0.74–0.83 for men and 0.80–0.97 for women. Bland-Altman plots have indicated a largely homoscedastic distribution of the test-retest parameters. The standard error of measurement (SEM) varied from 3.6–7.00 Nm for men and 3.3–4.7 Nm for women (highest PT-based) and 2.9–5.7 Nm for men and 1.6–4.0 Nm for women (mean PT-based). Irrespective of either paradigm, there was much dispersion in the ICCs for both genders in other isokinetic parameters such as the time to PT and angle at PT. It is therefore concluded that the only reproducible isokinetic parameter under this test protocol is the peak torque.
Influence of body position on shoulder rotator muscle strength during isokinetic assessment
Authors: Radaelli Régis , Bottaro Martim , Weber Fernanda , Brown Lee E. , Pinto Ronei S.
Published: October 2018

The purpose of this study was to compare the effect of two different positions of shoulder internal rotation (IR) and external rotation (ER) on isokinetic concentric and eccentric peak torque as well as conventional and dynamic ratios. Nineteen athletes (Eigth judo and eleven tennis players), (20.3± 5.2 yrs) performed 5 maximal unilateral isokinetic concentric shoulder IR and ER repetitions at 60°/s and 120°/s. The subjects also performed 3 and 5 maximal eccentric shoulder ER repetitions at 60°/s and 120°/s respectively. The tests were performed in two seated positions: 1) with the shoulder abducted in the scapular plane, and 2) with the shoulder flexed in the saggital plane. Shoulder dynamic control ratio (DCR) and conventional ratio were also assessed. The scapular plane position showed significantly (p < 0.05) greater peak torque(PT) values than the saggital plane position during concentric IR at both speeds. However, the saggital plane position PT values were significantly greater during concentric and eccentric ER in both speeds. Additionally, the DCR and the conventional ratio values were significantly greater for the saggital plane shoulder position. These results suggest that test position is an important control variable in isokinetic shoulder IR and ER testing.
Changing filtering parameters affects lower extremity pre-landing muscle activation onset times
Authors: Ambegaonkar Jatin P. , Shultz Sandra J.
Published: October 2018

Surface electromyography(sEMG) is extensively used to examine muscle activation. Although raw sEMG signals are often filtered using Root-Mean-Square(RMS) algorithms, little agreement exists as to the time window over which signals should be processed. We examined the effects of differing RMS filtering windows on muscle onset times. Fifty-five participants performed 5 drop jumps from a 45 cm box and lateral gastrocnemius(LG), medial and lateral hamstring(MH, LH) and lateral quadriceps(LQ) muscle activity were acquired. Signals were collected at 1000 Hz and RMS filtered using 3 ms, 10 ms, 20 ms and 25 ms windows. Muscle onset times differed by RMS windows for the LG(p= 0.01), MH(p= 0.002), and LH(p= 0.000), but not for the LQ(p=0.14). Pairwise comparisons indicated that LG onsets were earlier with the 3 ms vs. 20 ms window, MH onsets were earlier with the 3 ms vs. 20 ms and 25 ms windows, and LH onsets were earlier with the 3 ms, 10 ms, and 20 ms windows than the 25 ms window. Gastrocnemius and hamstring muscle onset times were substantially earlier when filtering raw sEMG data with 3 ms versus wider RMS windows(> 20 ms) during landing. Changing filtering parameters affects data interpretation when analyzing sEMG data using differing window widths. Additional research should determine optimal RMS window widths that maximize signal fidelity but still retain meaningful time differences.
The effect of isokinetic exercise on symptoms, functional status and EMG activation onset time of the vastus medialis oblique and vastus lateralis in female patients with patellofemoral pain syndrome
Authors: Akkurt Ekrem , Salli Ali , Ozerbil Onder Murat , Ugurlu Hatice
Published: October 2018

The aim of this study was to evaluate VMO and VL EMG activation onset times (AOT) during isometric contractions at various degrees of knee flexion and to explore the effects of a 6-w isokinetic exercises program on pain, quality of life, muscle strength and, if observed, on the difference in AOT, in patients with patellofemoral pain syndrome (PFPS). Twenty two female patients suffering from anterior knee pain and diagnosed with PFPS were recruited. The main outcome measures consisted of AOT and maximal isometric contraction of VMO and VL muscle and Medical Outcomes Study (SF36) and VAS scores. Compared to control knees, pre-exercise measurements revealed significant delay only in VMO at knee flexion angles of 15°, 30°, 45°. Post-exercise measurements showed improvement in the delay at 15°, 30°, 45° and also in the other pain, health quality and muscle strength measurements. In conclusion; VMO is activated later than VL in PFPS patients while exercise results in improvements in both symptoms and delay in VMO.
Effects of a 60∼second maximum voluntary isometric contraction on torque production and EMG output of the quadriceps muscle group
Authors: Katakura Mai , Duffell Lynsey D. , Strutton Paul H. , McGregor Alison H.
Published: October 2018

Background: Fatigue is thought to impact performance and may be a factor in injury mechanism. However, the full impact of a potentially fatiguing task on performance is unclear.

Objective: To explore changes in maximum voluntary torque and electromyographic (EMG) activity following a sixty second isometric maximum voluntary contraction (MVC) of the quadriceps muscles and to follow the time course of any changes observed.

Method: 21 subjects (14 males and 7 females) were recruited. Torque during brief maximum voluntary isometric contractions of the quadriceps muscle group was recorded in right and left legs using a Cybex Norm Isokinetic Dynamometer before, during and at intervals after a 60 second isometric fatigue task. EMG activity of the vastus medialis, rectus femoris and vastus lateralis was also recorded synchronously.

Results: Mean peak torque was significantly (p< 0.05) lower in both legs at the end of the fatigue task. However, 10 minutes following the cessation of the task, it had increased and was significantly higher than the pre-fatigue level. It remained higher until the end of the protocol (30 mins post fatigue). The EMG amplitudes decreased slightly compared to pre-fatigue values during the fatigue task, a few of which were significantly lower than those of the pre-fatigue task. Following the fatigue task, EMG amplitudes increased gradually and were significantly higher than those of the pre-fatigue task in all the muscles at the final time point. Median frequencies decreased significantly during the fatigue task and were similar to pre-fatigue values by 5mins post-fatigue.

Conclusion: This study has revealed that both torque and EMG rise following a sustained isometric 60 second hold to higher levels than pre-hold and that this rise is maintained for up to 30 minutes. This rise however, was not associated with increased muscle firing frequency. The mechanisms behind this rise remain to be elucidated.
Invertor and evertor strength in track and field athletes with functional ankle instability
Authors: Edouard Pascal , Chatard Jean-Claude , Fourchet François , Collado Hervé , Degache Francis , Leclair Anthony , Rimaud Diana , Calmels Paul
Published: October 2018

Background: In track and field, the load of impact, the coordination and the constraints on the ankle could result in adaptations of the ankle dynamic stabilization. These constraints could play a strengthening role and increase invertor and evertor strength also after a previous history of lateral ankle sprain.

Objective: To compare the ankle invertor and evertor isokinetic strength in track and field athletes (i) with functional ankle instability(FAI), (ii) with history of lateral ankle sprain but without functional ankle instability, and (iii) without any history of lateral ankle sprain.

Methods: Twenty-five track and field athletes (5 female and 20 male, 22 ± 5 years) were included in this cross-sectional controlled study, and divided into 3 groups for comparison: (i) athletes with FAI, (ii) athletes with a previous history of lateral ankle sprain, and (iii) a control group of healthy athletes. The dominant side ankle invertor and evertor isokinetic strength were evaluated concentrically at 120 and 30°/s while the evertor strength was also tested eccentrically at 30°/s.

Results: No significant differences were indicated between the muscle strength of the three groups, except for the concentric evertor peak torque and the evertor-to-invertor ratio (EIR) at 30°/s (P < 0.05). The concentric evertor peak torque and EIR at 30°/s were significantly lower in the group of athletes with a previous history of ankle sprain than in the control group (P <0.05).

Conclusion: Functional ankle instability and/or history of lateral ankle sprain in track and field athletes were not associated with strength weakness of the invertor or evertor muscles. However, as the EIRs were higher than 1.0 for the healthy track and field athletes and those with FAI, it is suggested that the track and field constraints result in adaptations of the ankle dynamic stabilization and then influence invertor and evertor strength balance.
The impact of contractile mode and work volume on the prediction of cortisol concentrations from flywheel-based resistive exercise workouts
Authors: Caruso J.F. , Coday M.A. , Mason M.L. , Lutz B.M. , Shepherd C.M. , Davidson M. , Duncan J.J.
Published: October 2018

To assess cortisol concentrations (CC) from flywheel ergometer resistive exercise, subjects performed three different leg press workouts on the device. Comprised of ten-repetition sets, the workouts entailed 1): a three-set protocol composed of concentric and eccentric actions (CE3), as well as concentric-only paradigms comprised of 2): three (CO3) and 3): six (CO6) sets. Venous blood draws, collected before workouts and at one and 30 minutes post-exercise, measured CC. ANOVA yielded CC results similar to studies that employed standard resistive exercise equipment. However multivariate regression revealed body mass, peak angular velocity and average power were strong predictors of post-exercise CC. Separate multivariate analyses of the CE3 and pooled concentric-only (CO3 and CO6 combined) data show differences in level of explained (r ^{2} ) variance, which was likely due to the ergometer's operation. Constant torque exertion throughout the CE3 bout meant performance was continual only for that workout and evoked more explained variance versus the concentric-only trials. The current ergometer was originally intended for use aboard manned spacecraft and is a prototype to newer flywheel-based resistive exercise devices. Future research should assess responses to workouts in a bed rest model to determine which protocol best abates CC to further aid future in-flight exercise.
Initial effects of kinesio® taping in patients with patellofemoral pain syndrome: A randomized, double-blind study
Authors: Aytar Aydan , Ozunlu Nihan , Surenkok Ozgur , Baltacı Gul , Oztop Pınar , Karatas Metin
Published: October 2018

The purpose of this randomized, double-blind study was to determine the acute effects of kinesio® taping on pain, strength, joint position sense and balance in patients with patellofemoral pain syndrome (PFPS). Twenty-two subjects with PFPS participated in the study. Subjects were separated into two groups; kinesio® taping (KT) and placebo kinesiotaping (PKT). All subjects were assessed before and 45-min after the applications. Muscle strength, joint position sense, static and dynamic balance and pain intensity were used as the main outcome measures. Among all outcome parameters significant differences were found between strength of quadriceps muscle at 60 and 180°/s, and static and dynamic balance scores before and 45-min after application of KT. There was also a significant difference between strength of quadriceps muscle at 60°/s and static balance scores before and 45 minutes after application of the PKT. Therefore KT application does not seem to be an effective treatment method for both decreasing pain and improving joint position sense for patients with PFPS.
The effect of contraction type on muscle strength, work and fatigue in maximal isokinetic exercise
Authors: Baroni Bruno Manfredini , Stocchero Cíntia Mussi Alvim , do Espírito Santo Rafaela Cavalheiro , Ritzel Cíntia Helena , Vaz Marco Aurélio
Published: October 2018

This study investigated knee extensor muscle strength, work and fatigue level under maximal isokinetic concentric and eccentric exercise. Seventeen male athletes were randomized into two groups and performed 10 sets of 10 maximal isokinetic concentric (N =8) or eccentric(N =9) contractions. Knee extensor peak torque and mean torque values per set were 54–121% and 53–133% higher in eccentric compared to concentric exercise, respectively, whereas the percent fall of performance in these variables was more accentuated in concentric exercise. Total work was significantly higher in eccentric exercise (19475 J) than concentric exercise (15758 J), while fatigue index was greater in concentric(36%) than eccentric (18%) exercise. In conclusion, maximal isokinetic eccentric exercise promotes larger overload to knee extensor muscles than its concentric counterpart due to higher torque produced by the muscle group and also thanks to minor muscle fatigue effects.