bluuebunny/crossref_metadata_2025 huggingface dataset:
Muscle oxygenation following concentric exercise
Authors: Ahmadi Sirous , Sinclair Peter J. , Davis Glen M.
Published: October 2018

We investigated the hypothesis that a session of maximal concentric contraction exercise (CE) might impair muscle oxygenation and muscle blood flow. Ten healthy males performed a single bout of 70 maximal elbow flexion CE. Before and after CE on day 1 and over the next two days, maximum voluntary isometric torque (MVT), plasma creatine kinase activity (CK), serum myoglobin, elbow joint range of motion (ROM), subjects' perception of muscle soreness(SOR), and muscle oxygenation kinetics (using near infrared spectroscopy; NIRS) within biceps brachii were assessed. MVT and ROM decreased while SOR increased significantly after CE (p<0.05), but recovered within the next day. There were not any significant changes in CK or myoglobin. Resting muscle oxygen saturation, oxyhaemoglobin and muscle oxygen uptake increased, and deoxyhaemoglobin decreased significantly after acute CE, and recovered by day 2. Although the changes in NIRS-derived variables were not significant in most conditions during isometric contractions of different intensities(i.e. 30%, 50% and 80% of MVT), there was a consistent pattern of change for those variables (i.e. decreasing immediately after CE, recovering on day 2 and increasing on day 3). Interestingly, the pattern of change in NIRS parameters mirrored CE-induced changes of MVT. In conclusion, concentric exercise did not produce prolonged changes in muscle oxygenation. The changes observed in NIRS-derived variables under resting condition may reflect an excess post exercise oxygen consumption.
Relationship between pedaling rate and physiological responses during passive leg cycling
Authors: Muraki Satoshi , Tsunawake Noriaki
Published: October 2018

The purpose of this study was to investigate the influences of pedaling rate during passive leg cycling (PLC) on respiratory and cardiac responses in able-bodied subjects. Ten male and ten female subjects performed PLC on an electric motor-controlled ergometer that provides constant-rate pedaling. After PLC at 20 rpm for 5 min, the pedaling rate was gradually increased by 5 rpm every 1 min until 70 rpm was attained. Gas exchange responses, heart rate, and muscle oxygenation were measured during rest and PLC. The increases in ventilation, oxygen uptake, and heart rate in both sexes accelerated when the pedaling rate exceeded a threshold of between 20–45 rpm. Over this threshold, they increased linearly, not exponentially. These results suggest that respiratory and cardiac responses were influenced by the pedaling rate during PLC and were promoted at a low pedaling rate.
Isokinetic ankle plantarflexion and dorsiflexion strength in patients with rheumatoid arthritis
Authors: Eyigor Sibel , Kirazli Yesim , Capaci Kazım , Oder Gonca , Tarhan Figen , Inal Vedat
Published: October 2018

Backgroud and objectives: In patients with rheumatoid arthritis(RA), some muscle groups are affected in different stages of disease, especially those related to the affected joint. However, data on associations between functional performance and muscle strength in RA are few. Therefore we sought to determine whether isokinetic ankle plantarflexion (PF) and dorsiflexion (DF) strength was affected in RA patients and to study the association between isokinetic strength and other clinical indicators of disability such as walking and stair-climbing time and disease activity in patients with RA.

Methods: Thirty three patients diagnosed with RA in the chronic phase were selected from a rheumatology outpatient clinic and matched for age and gender with 33 healthy subjects. Isometric and isokinetic muscle strength was measured in DF and PF. The subjects were also evaluated through the Stanford Health Assessment Questionaire (HAQ), walking and stair-climbing time. Cumulative and current steroid doses (CSD) were calculated.

Results: No significant correlations were found between muscle strength and visual analogue scale (VAS) scores, HAQ, ankle involvement, CSD (p>0.05). With respect to the isokinetic parameters, no differences have been been observed between RA and control groups (p>0.05). Walking and stair-climbing time increased significantly (p<0.05) in patients with RA.

Conclusions: Ankle isokinetic muscle strength is not affected in inactive RA patients while negative effects of steroids on muscle strength were not demonstrated. Important determinators of walking ability in RA patients should be defined in future studies.
Effect of time-of-day on neuromuscular properties of knee extensors after a short exhaustive cycling exercise
Authors: Nicolas A. , Gauthier A. , Bessot N. , Moussay S. , Thibault G. , Sesboüé B. , Davenne D.
Published: October 2018

We investigated the effect on neuromuscular properties of the knee extensors of an exhaustive cycling exercise performed at 6AM and 6PM. Eleven well trained cyclists performed a maximal aerobic exercise consisting in a sustained effort at 95% of their maximal power until exhaustion(T $_{lim}$ ). Isometric maximal voluntary contraction (MVC) and electromyographic activities (root mean square: RMS) of the vastus lateralis were recorded before (pre-test) and immediately after (post-test) the cycling exercise. The MVC/RMS ratio was calculated and used as an index of neuromuscular efficiency (NME). Rectal temperature was recorded continuously throughout the test session. Results show that T $_{lim}$ cycling exercise was not time-of-day dependent (p=0.42). A significant interaction effect of time of day and the cycling exercise was demonstrated for MVC (p<0.02) and NME(p<0.05). In pre-test, MVC and NME were higher in the late afternoon than in the morning (+6.8%); however both parameters were more affected by the T $_{lim}$ exercise at 6PM than at 6AM. These results suggest that following cycling T $_{lim}$ exercise, neuromuscular properties of the knee extensors are more affected in the evening than in the morning. However, circadian rhythm of some biomechanical parameters implicated in the pedalling movement may modulate the effect of these diurnal variations.
Hip external and internal rotation strength: Consistency over time and between sides
Authors: Bohannon Richard W. , Vigneault Jeremy , Rizzo Jon
Published: October 2018

Little research has focused on the measurement of both hip external and internal rotation strength. The purpose of this study was to describe the consistency of isometric hip rotation forces measured by hand-held dyanamometry. Specifically, we described the consistency over time and between sides. For 15 subjects measured during 2 sessions one week apart, rotation forces and force ratios did not differ significantly. Intraclass correlation coefficients (ICCs) were high (0.836–0.944) except for the external to internal rotation force ratio on the right side (0.367). For 32 subjects measured during 1 session, hip external rotation forces and rotation force ratios did, but hip internal rotation forces did not, differ between sides. The between-side ICCs were high for the force measures (0.897&0.901) but not for the force ratio (0.337). Unlike force ratios, isometric force measurements obtained during a previous test session or from the other side provide a basis for measurement interpretation. The method errors and coefficients of variation of the method error that we report may be helpful in such interpretation.
The influence of menstrual cycle on ankle proprioception
Authors: Hesar N. Ghani Zadeh , Calders P. , Thijs Y. , Roosen P. , Witvrouw E.
Published: October 2018

The purpose of this study was to investigate the effect of the three phases (menstrual, follicular, luteal phase) of the menstrual cycle on active and passive ankle joint position sense. Twenty five healthy women with regular menstrual cycle, not pregnant and no contraceptive using with normal and consistent length of menstrual cycle and bleeding days participated in the study. Blood samples were collected from each subject for determination of hormonal level the phases of menstrual cycle. Ankle joint position sense changes during three different phases of the menstrual cycle were assessed. Active and passive joint position sense of dominant leg of subjects was measured using the Biodex 2 isokinetic dynamometer. The absolute reposition errors from the target angles have been evaluated by repeated measure analysis of variance (ANOVA) in three hormonally verified phases of menstrual cycle. No significant interaction was observed between ankle joint position sense test and the phases of the menstrual cycle. We did not identify ankle joint position sense alteration across the menstrual, follicular and luteal phases. We suggest that the menstrual cycle does not significantly affect ankle joint position sense.
Time-of-day effects during acute isokinetic exhaustive eccentric exercise: Serum leptin response
Authors: Lappalainen Zekine , Kilinc Fatih , Lappalainen Jani , Atalay Mustafa
Published: October 2018

Circadian rhythms are known to influence muscular performance and regulate leptin hormone secretion, which assists in the regulation of body weight and energy homeostasis. In this study we examined the time-of-day effect on skeletal muscle eccentric contractile properties and the response of serum leptin to acute eccentric exhaustive isokinetic exercise. Male subjects(n = 26) performed a bout of exhaustive eccentric exercise on an isokinetic dynamometer in the morning or late afternoon time on different days. The test was repeated after 7–10 days at different time-of-day. Blood samples were collected at baseline and immediately after exercise for determination of serum leptin. Leg extensor muscle torque and work parameters were recorded, and compared with the time-of-day. Maximal eccentric torque values were not significantly affected by time-of-day. The maximal work performed during single repetition as well as total work values were significantly higher in the afternoon time. Leptin levels significantly decreased after exercise, but no time-of-day effect on serum leptin could be observed. Diurnal variations during short-term isokinetic exhaustive eccentric exercise seem to reflect muscle work capacity, with higher contractile efficiency towards the evening time. Although short-term exhaustive eccentric exercise decreased serum leptin, the levels did not to have a significant diurnal variation.
Cardiopulmonary exercise data during quadriceps isometric contraction sustained to fatigue in children with cerebral palsy
Authors: Leunkeu Angeline Nsenga , Gayda Mathieu , Nigam Anil , Lecoutre Noël , Ahmaidi Said
Published: October 2018

The aims of this study were to: 1) study the cardiopulmonary responses during exhaustive isometric contraction in cerebral palsy (CP) children vs. apparently normal (AN) children 2) to study the relationship between muscle endurance and maximal O $_{2}$ uptake (peak VO $_{2}$ ) in CP children. Eight CP children (GMFC 1 to 2) and 8 AN children underwent a graded cycle exercise test and a quadriceps force and endurance assessment with cardiopulmonary measurement on an isokinetic dynamometer. During isometric contraction, muscle endurance did not differ between the groups but a higher O $_{2}$ uptake was shown in the CP group. Moreover in this group, peak VO $_{2}$ was correlated with muscle strength (R = 0.77, P < 0.05) and endurance (R = 0.68, P< 0.05). Cerebral palsy children have a higher O $_{2}$ uptake during isometric endurance testing despite a lower absolute isometric force but their quadriceps endurance is not impaired after normalization with muscle mass and time. Additionally, quadriceps strength and endurance in CP children were in relationship with their peak VO $_{2}$ . This higher O $_{2}$ uptake is probably due to coactivation and/or cocontraction during exhaustive quadriceps isometric contraction.
The effect of gravitational correction on shoulder internal and external rotation strength
Authors: Edouard Pascal , Calmels Paul , Degache Francis
Published: October 2018

Objective: To study the influence of gravitational correction on the internal (IR) and external rotators (ER) shoulder strength.

Methods: The IR and ER isokinetic strength, measured in 30° scapation, was evaluated concentrically at 60 and 240°/s and eccentrically at 60°/s in 33 healthy volunteers. Strength scores were expressed either by incorporating gravitational correction (GC) or without it.

Results: With GC, IR strength was significantly lower and ER strength significantly higher than without incorporation of this procedure.

Conclusion: The GC procedure has a significant influence on IR and ER strength and should be incorporated when strength deficits of the rotator cuff are expected.
Performed vs. predicted static endurance of the back extensors: Correlation or conflict
Authors: Mbada C.E. , Ayanniyi O.
Published: October 2018

Background and objective: Identifying methods of accurately predicting endurance capacity of the back extensor muscles is of immense value to both patients and clinicians. This study aimed to develop a multiple regression equation using demographic and anthropometric measurements to predict back endurance and to investigate the association between performed back endurance results and back endurance predictions.

Materials and methods: 376 healthy women and men aged 21–62 y were recruited consecutively. All participants underwent the Biering-Sørenson test of Static Muscular Endurance. Height and weight were measured using standard procedures. Percentage body fat was estimated using bioelectrical impedance analysis. Body mass index, lean body mass and body fat mass were calculated. Based on these a regression model was used to generate predictive equation for endurance time.

Results: The final regression model which included demographic and anthropometric variables could account for 43% of the variability in back muscle endurance. Pearson's product correlation coefficient for the association between performed static endurance and the predicted endurance were(r = −0.129; p = 0.074) and (r = 0.671; p = 0.000) for male and female participants respectively. Paired t-test showed significant difference (p = 0.000) between the performed static endurance and predicted endurance among the male participants but not among the female counterparts (p = 0.959). Endurance time of males (119 ± 49.8 secs.) was significantly greater (p = 0.014) than that of the females (106 ± 47.6 secs.).

Conclusion: Regression equation seems to be moderately valid in predicting endurance time of the back extensors among females only. We conclude that simple anthropometric measures cannot accurately predict back endurance without significant errors. The larger error of prediction obtained for the male participants could be indicative of an increasing influence of motivational/psychosocial factors that are known to be independent of motor ability in physical performance testing.
Cardiovascular responses during isokinetic knee extension testing in chronic heart failure patients
Authors: Degache Francis , Roche Frédéric , Bernard Pierrick , Calmels Paul
Published: October 2018

Background: Isokinetic testing imposes severe cardiovascular stress which must be taken into consideration particularly when at risk patients are involved.

Objective: To assess the effects of isokinetic tests on heart rate(HR) in stable chronic heart failure (CHF) patients.

Subjects: Twenty five CHF patients, 23 men, 2 women.

Intervention: After a 10-min warm-up on a cycle ergometer, one lower limb was tested isokinetically using 3 successive repetitions of knee flexion-extension at 60 and 180°/s and 20-repetitions at 240°/s. Heart rate was recorded on average over 5 sec and was analyzed at the start and end of each exercise. Peak ˙VO $_{2}$ was assessed during maximal incremental test on the ergometer.

Results: Maximal values (117.6 ± 22.0 bpm) of HR were obtained during incremental exercise testing which corresponded to 97.6 ± 14.0% of maximal HR noted at peak ˙VO $_{2}$ .

Conclusion: Isokinetic muscle strength testing in CHF patients must be performed under the supervision of an experienced clinician who should judge the value and feasibility of the endurance test.
Isokinetic evaluation of muscle strength in patients with thyroid dysfunction
Authors: Kocabas Hilal , Yazicioglu Gokhan , Karaman Nehir Samanci , Balci Nilufer Vedin , Balci Mustafa Kemal
Published: October 2018

Skeletal muscle weakness is a frequent symptom of thyroid dysfunction. Both hypothyroidism and hyperthyroidism may cause signs and symptoms of neuromuscular dysfunction. It has been reported in previous studies that muscle strength recovers after treatment of thyroid dysfunction. The aim of the current study was to evaluate knee extensors and flexors strength in patients with thyroid dysfunction before and after medical treatment and compare the data with those of a matched control group. For this purpose 11 hyperthyroid, 9 hypothyroid patients and 27 healthy controls were recruited. All were tested isokinetically on the dominant side. The results suggest that return of thyroid hormone concentrations to their reference ranges, significantly increases muscular strength in hyperthyroid patients. However there was no significant recovery in the hypothyroid group. Nevertheless in both groups post-treatment muscle strength was significantly lower than in the control group. The findings suggest that patients with thyroid dysfunction, especially with hypothyroidism, should train for muscle strengthening after establishing euthyroidism to obtain optimum life conditions.
The effect of fatiguing exercise on balance performance as measured by the balance error scoring system
Authors: Erkmen Nurtekin , Taşkın Halil , Kaplan Turgut , Sanioǧlu Ahmet
Published: October 2018

The aim of the study was to investigate whether a fatiguing exercise on treadmill affects balance performance in recreationally active men and women. Nineteen subjects, aged 18–26 years, were assessed before and after a fatiguing exercise, using the Balance Error Scoring System (BESS). Fatiguing exercise was performed on treadmill using the Bruce protocol. A significant effect of fatigue was present in men (P < 0.05) and women(P < 0.05). Women performed at a significantly lower total BESS scores than men at both pretest (P < 0.05) and posttest(P < 0.05). The mean difference (posttest-pretest) between men and women was not significant (P > 0.05). These findings suggest that a fatiguing exercise induced by means of treadmill increases postural sway in healthy subjects, and that this increase in postural sway is sex-independent.
Hemodynamic response of an isokinetic testing and training∼session
Authors: Lamotte M. , Chevalier A. , Jamon A. , Brassine E. , van de Borne Ph.
Published: October 2018

Background: Isokinetic evaluation and training are commonly used. Hemodynamic response during this type of exercise is unknown and therefore usually not recommended in some patients (elderly, patients with risk factors or with cardio-vascular disease). The aim of this study was to evaluate the hemodynamic response during a classical testing and training isokinetic session.

Method: 20 healthy young male participated to this study. The hemodynamic response wa continuously and non invasively (Task Force Monitor) measured on a Cybex Norm (knee extension and flexion). The hemodynamic parameters were systolic blood pressure (SBP), heart rate (HR) and cardiac output (Q).

Results: A low speed (60°/s) test was more exhausting than one at higher speed (180°/s) which is probably related to its duration. Whereas rest periods seemed sufficient for muscle recovery allowing during training, maintenance of performance over the different sets, changes in hemodynamic parameters (HR, SBP & Q) were observed over successive sets and did not recover totally during rest. Systolic ejection volume did neither change nor contribute to the increase of cardiac output (+ 70 to 84% compared to rest). Values measured during test and training were high but not excessive (HR max=135 ± 20 bpm or 70% of HRmax predicted; SBP max=185 ± 26 mmHg; Q=11.2 ± 2.2 l/min).

Conclusions: Values measured during test and training are high but not excessive. Isokinetic training in cardio-vascular risk patients should be composed of shorter set duration and longer rest periods as generally applied, without loosing maximal muscle contraction over the entire rage of motion.
Risk factors for ankle sprain in volleyball players: A preliminary analysis
Authors: Hadzic Vedran , Sattler Tine , Topole Eva , Jarnovic Zoran , Burger Helena , Dervisevic Edvin
Published: October 2018

Injuries in volleyball are sport specific and occur around the net during spiking and blocking. The most common acute injury in volleyball is ankle sprain. There are limited data about the intrinsic risk factors for the ankle sprains in volleyball players. We investigated the influence of muscle strength, postural balance and active range of motion on the ankle sprain occurrence in volleyball players. In 38 professional volleyball players we have tested the strength of plantar and dorsal flexors using isokinetic dynamometer. Dynamic postural balance was measured using Biodex Balance System and active range of motion was tested by the means of universal goniometry. Following the testing players were prospectively followed up over a season, with injuries and exposure rates registered by the team coaches. Binary logistic regression was used to evaluate the role of individual risk factors. The main findings of our study indicate that higher strength of plantar flexors (odds ratio 1.22, 95% C.I. 1.04–1.43, p< 0.05) and decreasing range of motion in dorsiflexion (odds ratio 0.63, 95% C.I. 0.41–0.97) are significant risk factors for the ankle sprain. The results are suggesting that both risk factors are limiting the ability to land safely from a jump, and that plyometric exercises, proper landing technique and gastrocnemius stretching should be emphasized in the preventive training programs in volleyball players.
Effect of a previous high intensity running exercise on isokinetic muscular strength in individuals with different training backgrounds
Authors: Denadai Benedito Sérgio , Corvino Rogério Bulhões , Greco Camila Coelho
Published: October 2018

The objective of this study was to compare the effects of high intensity running exercise on the strength of the knee extensors at concentric and eccentric conditions in individuals with different training background. Sixteen physically active (SED), 11 endurance-trained (ET) and 7 strength-trained (ST) subjects volunteered to participate in the study. Initially each subject performed, on different days, one familiarization session on an isokinetic dynamometer and an incremental treadmill test to volitional exhaustion to determine the velocity at the onset of blood lactate accumulation (OBLA). The subjects then returned to the laboratory on two experimental sessions, separated by at least five days, to perform maximal isokinetic eccentric (E) and concentric (C) contractions of the quadriceps at 180°/s. One session was performed after a standardized warm-up period (5 min at 50%V VO $_{2}$ max) and the other session was performed after a continuous running at 95% OBLA. The duration of this session was estimated to a caloric expenditure around 500 Kcal. Following this high intensity exercise there was a significant reduction in the peak torque in E in all groups. The percent strength loss in E following the running exercise was statistically higher in ST (16.5%) when compared to SED (6.5%) and ET(7.2%). We thus conclude that the reduction in isokinetic peak torque of the knee extensors after a session of high intensity running exercise at 95% OBLA depends on the contraction type and training background.
Cardiovascular and metabolic responses during isokinetic shoulder rotators strength testing in healthy subjects
Authors: Edouard Pascal , Castells Josiane , Calmels Paul , Roche Frédéric , Degache Francis
Published: October 2018

Background: Although there have been many studies on isokinetic shoulder exercises in evaluation and rehabilitation programs, the cardiovascular and metabolic responses of those modes of muscle strength exercises have been poorly investigated.

Objective: To analyze cardiovascular and metabolic responses during a standardized test used to study the internal (IR) and external (ER) rotators maximal isokinetic strength.

Methods: Four days after an incremental exercise test on cycle ergometer, ten healthy subjects performed an isokinetic shoulder strength evaluation with cardiovascular (Heart rate, HR) and metabolic gas exchange (�O $_{2}$ ) analysis. The IR and ER isokinetic strength, measured in seated position with 45° of shoulder abduction in scapular plane, was evaluated concentrically at 60, 120 and 240°/s and eccentrically at 60°/s, for both shoulder sides. An endurance test with 30 repetitions at 240°/s was performed at the end of each shoulder side testing.

Results: There was a significant increase of mean HR with isokinetic exercise (P< 0.05). Increases of HR was 42–71% over the resting values. During endurance testing, increases of HR was 77–105% over the resting values, and corresponded to 85–86% of the maximal HR during incremental test. Increase of �O $_{2}$ during isokinetic exercises was from 6–11 ml/min/kg to 20–43 ml/min/kg.

Conclusion: This study performed significant cardiovascular and metabolic responses to isokinetic exercise of rotators shoulder muscles. A warm-up should be performed before maximal high-intensity isokinetic shoulder testing. Our results indicated that observation and supervision are important during testing and/or training sessions, especially in subjects with risk for cardiovascular disorders.
Effects of acute and 4-week submaximal exercise on leukocyte and leukocyte subgroups
Authors: Patlar Suleyman
Published: October 2018

The aim of this study is to investigate how does an acute 4-week submaximal exercise affect both leukocyte and leukocyte subgroups.

The study registered 8 healthy male subjects. The subjects were exercised on Monark 814-E and 818 model ergometric bicycles 3 times a week for 4 weeks at above threshold heart rate and 75% of Max VO $_{2}$ . Blood samples were collected three times from the subjects, before starting the exercise, immediately after finishing the last exercise and 2 hours after the last exercise. The samples were analyzed in HemaCell Counter (Skits) apparatus to quantify leukocyte, neutrophil, monocyte, eosinophil and basophil levels.

Leukocyte counts obtained in both post-exercise measurements were significantly higher than those before the exercise (p< 0.05). Neutrophil percentages two hours after exercise were higher than those before and immediately after exercise (p< 0.05). Lymphocyte percentages obtained just after exercise were elevated in comparison to those both before and two hours after exercise (p< 0.05). However, lymphocyte percentages two hours after exercise were significantly lower than the pre- and post-exercise percentages(p< 0.05). Percentages of monocytes, eosinophils and basophils in both post-exercise measurements were lower relative to pre-exercise values(p<0.05). In conclusion both acute and 4-week submaximal exercise have significant effects on leukocyte and leukocyte subgroups.
Comparison of lower limb muscle activation during downhill, level and uphill running
Authors: Cai Zong-Yan , Hsu Cheng-Chen , Su Chin-Peng , Lin Chin-Fan , Lin Yi-An , Lin Chin-Li , Hsu Mei-Chich
Published: October 2018

We compared the lower limb muscle activation during uphill running(UR), level running (LR), and downhill running (DR). Eight male physically active subjects ran three slopes for 30 min at the given speed (55% vVO $_{2}$ peak at LR), including DR (−6°), LR(0°), and UR (6°) in a random crossover, repeated measures design. Electromyographic (EMG) signals were collected from the dominated lower limb muscles: rectus femoris (RF), biceps femoris (BF), gastrocnemius (GAS), soleus, and tibialis anterior. Our results showed that greater EMG of RF was found with inclining slope (UR>LR>DR, p< 0.05); EMG of BF was greater during UR than during DR (p< 0.05); EMG of GAS differed significantly in the order: UR>DR>LR (p< 0.05). We concluded that significant differences regarding muscle activations among DR, LR, and UR were observed for the RF, BF, and GAS, especially when running opposing slopes (DR vs. UR). Additionally, when running toward uphill, the propulsive muscles, such as the RF and GAS seemed to exert more effort. In contrast, while running toward downhill, RF might work as an extensor muscle that was activated to a lesser extent, possibly due to its undergoing eccentric movement.
Spectral analysis of knee isokinetic extension curves of osteoarthritic patients
Authors: Almosnino Sivan , Sled Elizabeth A. , Costigan Patrick A. , Chalmers Alison , Stevenson Joan M.
Published: October 2018

Isokinetic assessment of knee extensors muscle group function in patients suffering from knee osteoarthritis has exclusively been achieved using time-domain based variables. While useful, these analyses do not quantify the conspicuously irregular moment-time pattern exhibited by the involved knee when compared to the contralateral knee. The purpose of this investigation was to assess whether the frequency content of the isokinetic curve can quantify this latter phenomenon. Thirty two patients with knee osteoarthritis participated in this study. Each participant performed 5 maximal concentric knee extensions bilaterally at 60°/s using an isokinetic dynamometer. For each time-domain extension curve, the power spectrum was calculated via Fast Fourier Transform and the maximum frequency content value contained within 99% of total signal power was extracted. Of the 32 participants, 26 exhibited higher frequency contents in the isokinetic curves obtained from their involved knee (p= 0.002, effect size =0.35). The results suggest that the frequency content of isokinetic moment-time curves may provide useful quantitative information regarding the smoothness of moment production, and as such, may be used in conjunction with traditional time-domain variables in the assessment of knee extensors function in patients suffering from knee osteoarthritis.
Isokinetic strength effects of FIFA's "The 11+" injury prevention training programme
Authors: Brito João , Figueiredo Pedro , Fernandes Luís , Seabra André , Soares José M. , Krustrup Peter , Rebelo António
Published: October 2018

The purpose of this study was to evaluate whether FIFA's Medical Assessment and Research Centre (F-MARC) injury prevention programme, "The 11+", improves isokinetic strength of the knee extensor and flexor muscles in sub-elite soccer players. Twenty players aged 22.3 ± 4.2 yr performed"The 11+" 3 times a week for 10 weeks. Isokinetic measurements were performed on the hamstrings and quadriceps muscles on both lower extremities at concentric 60 and 180°/s and eccentric 30°/s. The peak torque (PT) as well as conventional and dynamic control ratios (DCR) were calculated. Hamstrings PT in the non-dominant limb increased by 14.6%, 15.0% and 14.3% during the above contractions/velocities, respectively (p< 0.05). In the dominant limb the concentric PT of the quadriceps increased by 6.9% (60°/s) and 8.3% (180°/s) whereas that of the hamstring increased by 20.4%(60°/s), (p< 0.05). The training programme significantly improved the conventional H/Q ratio at 60°/s by 14.8{\%} and the DCR by 13.8% in the non-dominant limb (p< 0.05). Therefore, the "The 11+" training programme appears to be adequate and effective for soccer training and conditioning by improving strength and muscle balance around the knee joint.
Does knee joint alignment with the axis of the isokinetic dynamometer affect peak torque?
Authors: Houweling Taco A.W. , Hamzeh Maher A.
Published: October 2018

The aim of this study was to determine the reliability of five positions of alignment of the knee joint with the axis of a Cybex Norm isokinetic dynamometer.

Seventeen physically active males volunteered for this study. The knee joint was positioned in five xy-plane coordinates from the rotational axis of the dynamometer (cm): (0,0); (2,0); (4,0); (0,-2) and(0;-4). Repeated measures Analysis of Variance (ANOVA) and Ratio Limits of Agreement (RLOA) were calculated for knee extension and flexion peak torque in all positions of alignment.

The ANOVA demonstrated no significant differences in peak torque for knee extension (F(4,64) = 1.813, P> 0.05) and significant differences in peak torque for knee flexion (F(4,64) =5.760, P < 0.05). The RLOA showed a standard bias ranging from −7 to−12% and systematic error ranging from 21 to 29% for knee flexion.

Knee extension peak torque did not significantly change when the knee joint was misaligned with the axis of the dynamometer. However, knee flexion peak torque was significantly affected when the knee was moved away both horizontally and vertically from the centre of the axis of the dynamometer.
Sit-to-stand test: Performance and determinants across the age-span
Authors: Bohannon Richard W. , Bubela Deborah J. , Magasi Susan R. , Wang Ying-Chih , Gershon Richard C.
Published: October 2018

Although the validity of the sit-to-stand (STS) test as a measure of lower limb strength has been questioned, it is widely used as such among older adults. The purposes of this study were: 1) to describe five-repetition STS test (FRSTST) performance (time) by adolescents and adults and 2) to determine the relationship of isometric knee extension strength (force and torque), age, gender, weight, and stature with that performance. Participants were 111 female and 70 male (14–85 years) community-dwelling enrollees in the NIH Toolbox Assessment of Neurological and Behavioral Function. The FRSTST was conducted using a standard armless chair. Knee extension force was measured using a belt-stabilized hand-held dynamometer; knee extension torque was measured using a Biodex dynamometer. The mean times for the FRSTST ranged from 6.0 sec (20–29 years) to 10.8 sec (80–85 years). For both the entire sample and a sub-sample of participants 50–85 years, knee extension strength (r=−0.388 to −0.634), age(r=0.561 and 0.466), and gender (r=0.182 and 0.276) were correlated significantly with FRSTST times. In all multiple regression models, knee extension strength provided the best explanation of FRSTST performance, but age contributed as well. Bodyweight and stature were less consistent in explaining FRSTST performance. Gender did not add to the explanation of FRSTST performance. Our findings suggest, therefore, that FRSTST time reflects lower limb strength, but that performance should be interpreted in light of age and other factors.
Is there a correlation between intraindividual variability in isokinetic knee extension/flexion and muscle fatigue?
Authors: Skurvydas Albertas , Brazaitis Marius
Published: October 2018

The aim of this study was to test the hypothesis that intraindividual variability in isokinetic knee extension/flexion relates positively to muscle fatigue, i.e., the less the muscle fatigue during exercise, the greater is the variability of torque fluctuation. Twelve healthy males performed 100 continuous knee extensions and flexions with maximal intensity at 180°/s. The main findings were: 1) the knee extension muscle exhibited more fatigue and less intraindividual variability than the knee flexion muscles; 2) intraindividual variability in knee extension (SD for torque fluctuation in 100 repetitions) relates closely to fatigue. We conclude that intraindividual variability in isokinetic knee-extension torque relates inversely to muscle fatigue.
Musculo-tendinous stiffness of the in vivo head-neck segment in response to quick-releases: A reproducibility study
Authors: Portero Raphaël , Lecompte Jennyfer , Thoumie Philippe , Portero Pierre
Published: October 2018

This study was designed to assess the reproducibility of head-neck musculo-tendinous stiffness (HMS) findings of the head-neck segment in response to quick-release in flexion and extension. The HMS was expressed as the slope of the isometric torque-angular displacement curve of the head-neck segment derived from the first 15 ms from the peak acceleration following release at different exertion levels (10% to 80% MVC). A test--retest methodology (7 days interval) was performed to assess the measurement reproducibility. The results showed a linear relationship between the flexion and extension torque and angular displacement (0.94 < R $^{2} $ < 0.99). Moreover, HMS findings evidenced good to excellent reproducibility using relative (ICC) as well as absolute (SEM) parameters. It was concluded that that simple kinematic assessment was appropriate for investigating HMS. Nevertheless, multiple-segmentation of the head-neck segment could lead, according to exertion level, to geometrical changes after the release.
Correlations between knee extensor strength measured by a hand-held dynamometer and functional performance in patients with chronic stroke
Authors: Kobayashi Toshiki , Leung Aaron K.L. , Hutchins Stephen W.
Published: October 2018

The aim of this study was to investigate the correlations between knee extensor strength of the affected lower limb in patients with chronic stroke and other functional performance tests. Ten subjects with post-stroke hemiparesis (10 males; 54.3 ± 8.4 years old), who suffered from stroke for more than three years (duration of 8.7 ± 4.5 years) participated in this study. Knee extensor strength was measured using a hand-held dynamometer. Gait velocity was assessed when performing a 5-metre walk (5MWV), and additional parameters [the 5-minute walking distance(5MWD), the functional reach test (FRT), a timed up-and-go test (TUG) and Berg balance scale (BBS)] were also assessed as parameters of functional performance in each subject. It was demonstrated that knee extensor strength had significant Pearson's r correlation with 5MV (r=0.459, p< 0.05), FRT (r=0.781, p< 0.01), TUG (r=−0.538, p< 0.01) and BBS (r=0.758, p< 0.05). Therefore, knee extensor strength may be a moderate to good predictor of functional performance in patients with chronic stroke hemiparesis.
Reproducibility of ankle dorsiflexor muscle strength measurements in individuals with post-polio syndrome
Authors: Flansbjer Ulla-Britt , Drake Anna Maria , Lexell Jan
Published: October 2018

The aim of this study was to assess the reproducibility of isokinetic and isometric ankle dorsiflexor strength measurements in individuals with post-polio syndrome (PPS). Thirty-one men and women (mean age 63 ± 7.0 years) with verified PPS, participated in an intra-rater test-retest reproducibility study. Strength of the ankle dorsiflexor muscles in both lower limbs were measured twice, seven days apart, with a Biodex dynamometer(isokinetic concentric; 30°/s and isometric; ankle plantar flexion angle 10°). Reproducibility was evaluated with the intraclass correlation coefficient (ICC $_{2,1}$ ), the mean difference between the test sessions (�) and the 95% confidence intervals for �, the standard error of measurement (SEM, 95% SEM and SEM%) and Bland & Altman graphs. All 31 individuals completed the measurements in the less affected lower limb, but only 14 in the more affected lower limb due to severe weakness and/or joint stiffness. The analysis was therefore based on data from the two lower limbs separately. The test-retest agreements were high,(ICC $_{2,1}$ 0.85 to 0.94) and measurement errors generally small, and there was no discernible difference between the less and more affected lower limbs. The mean isokinetic and isometric peak torque (Nm) for the two lower limbs from the two test sessions ranged from 22.7 to 25.8. The SEM, which represents the limit for the smallest change that indicates a real change for a group of individuals, ranged from 2.51 to 3.74 Nm. In conclusion, isokinetic and isometric muscle strength measurements of the ankle dorsiflexor muscles in individuals with PPS are reproducible and can be used to detect changes over time or after an intervention for groups of individuals.
Relative reliability of three objective tests of limb muscle strength
Authors: Bohannon Richard W. , Bubela Deborah J. , Magasi Susan R. , Gershon Richard C
Published: October 2018

If measures of muscle strength are to be broadly applied, they should be objective, portable, quick, and reliable. Through this component of the NIH Toolbox study we sought to compare the test-retest reliability of 3 tests of muscle strength that are objective, portable, and quick: the five-repetition sit-to-stand test (FRSTST), hand-grip dynamometry (HGD), and belt-stabilized hand-held dynamometry (BSHHD) of knee extension. Three sets of each test were performed- 1 warm-up and 2 maximal. Measures from the maximal tests obtained 4 to 10 days apart were compared. Reliability was described using descriptive statistics, intraclass correlation coefficients (ICCs) and 4 measures of response stability: standard error of measurement (SEM), method error (ME), coefficient of variation of SEM (SEM _{CV} ), and coefficient of variation of variation of ME (ME _{CV} ). The ICCs of all tests were good (⩾ 0.853). Measures of response stability showed less variability between test and retest for FRSTST and HGD than for BSHHD. In conclusions all 3 tests demonstrated good test-retest reliability. However, greater differences would need to be observed between tests sessions to conclude that a real change had occurred in measures obtained by BSHHD.
Does kinesiotaping increase knee muscles strength and functional performance?
Authors: Aktas Gulcan , Baltaci Gul
Published: October 2018

Context: Knee injuries which are the most common disabling injuries in both athletic and physically active people, can be expected to occur with all sporting activities especially contact sports. Therefore, knee braces and taping techniques are widely used to reduce and/or prevent the severity and incidence of knee injuries in sports.

Objective: To determine which application, knee brace, kinesiotaping (KT) or both, is more effective regarding muscular strength and functional performance.

Design: A prospective, criterion-based controlled study.

Setting: University research laboratory.

Patients or other participants: Twenty (11 F, 9M) healthy subjects with no previous history of lower extremity injuries and using knee brace and KT were included in this study.

Main outcome measures: Muscular strength, and jump performance were tested with knee brace, kinesiotaping and both applications. Repeated measures ANOVA was performed to determine if there were differences between braced, taped and both conditions. Participants filled in a questionnaire regarding demographic and lower extremity problems.

Results: Kinesiotape application brought about a significant increase in hop distance (p=0.015, P=0.018) in both the dominant and non-dominant extremity and in isokinetic knee extension peak torque (p=0.034) at 180°/s.

Conclusion: KT application was more effective in terms of muscular strength and jump performance than knee brace and KT plus knee brace. Physical therapists and athletic trainers may apply KT to a patient during or after treatment and rehabilitation to support knee musculature, to encourage the tissue healing process, and to avoid limiting the enhancement of improved knee muscle performance.
Effect of static stretching and jogging on knee extension isokinetic peak torque
Authors: Sobolewski Eric J. , Wagner Dale R. , Bressel Eadric
Published: October 2018

The purpose of this study was to determine whether static stretching alone or combined with a warm-up affected isokinetic peak torque (IPT) of the quadriceps at both slow and fast velocities. Twenty physically active males(22.1 ± 2.4 years) performed maximal knee extensions under four conditions: no stretch control, stretch only, 5 min jog followed by stretches, and stretching followed by a 5 min jog. Total stretching volume was 360 s. A Biodex System 3 isokinetic dynamometer was used to measure IPT at 60 and 300°/s. A 2 × 4 repeated measures ANOVA revealed that IPT was significantly different among the four test conditions (F=3.09, p=0.03) and follow-up comparisons revealed that the mean IPT of the stretching trial was 9.9 N·m less than the control trial (Effect size=0.19–0.42). Neither of the warm-up conditions combined with stretching were significantly different from the control. It was concluded that stretching affects IPT to a similar extent at both velocities tested, and that jogging done either prior to or after stretching does not appreciably alter knee extension IPT. The lower IPT following static stretching precludes recommending this activity prior to a maximal effort.
Testing of knee extension muscle strength: A comparison of two portable alternatives for the NIH toolbox study
Authors: Wang Ying-Chih , Bohannon Richard W. , Magasi Susan R. , Hrynkiewicz Beata , Morales Aaron , Gershon Richard C. , Rymer Zev
Published: October 2018

Given the functional and epidemiological significance of lower extremity strength, portable, low-cost measures of lower extremity strength with robust psychometric properties are needed for clinical practice and research. The purpose of this study was to compare measures of isometric knee extension strength obtained with portable devices with criterion measures obtained with a Biodex dynamometer. Sixty-eight healthy adults from Illinois and Connecticut participated in this study. Each participant's isometric knee extension strength was tested in random order using: 1) an integrated tension load cell device (ITLCD), 2) a belt stabilized hand held dynamometer (BSHHD) and 3) a Biodex System 3 isokinetic dynamometer. Equivalence of the 3 measures was evaluated using repeated measures analysis of variance (ANOVA), Pearson correlations (r), and intraclass correlation coefficients (ICCs). Results supported good agreement between measures obtained with the ITLCD, BSHHD and Biodex (r > 0.90, ICCs > 0.79). The ANOVA results demonstrated that measures obtained with the ITLCD and the BSHHD did not differ significantly. On average, the maximum isometric knee extension torque was underestimated by 27 N-m and 32 N-m by the ITLCD and BSHHD, respectively. Because The ITLCD was slightly better at approximating Biodex torque scores and does not depend on skills of the examiner, the ITLCD was recommended for inclusion in the motor battery of the NIH Toolbox.
The effects of 6-weeks patellofemoral bracing on quadriceps muscle function
Authors: Van Tiggelen D. , Coorevits P. , Bernard E. , Thijs Y. , Witvrouw E.
Published: October 2018

Background: Previous studies have indicated that wearing a patellofemoral brace during strenuous training resulted in a decreased incidence of anterior knee pain (AKP). However whether this effect is derived from quadriceps enhancement remains unknown.

Study design: Randomized controlled clinical trial.

Methods: Ninety-eight military recruits, 35 'with-brace' and 63 without, underwent concentric isokinetic tests at 60 and 240°/s of the quadriceps prior to and following a 6-week basic military training (BMT). The randomly selected 35 subjects 'with brace' received a pair of patellofemoral braces (On-Track, DJ Ortho) and were instructed to wear these braces throughout training.

Results: Baseline strength characteristics of the quadriceps were not significantly different between the braced and non-braced group (p > 0.05). No significant time-effect was observed in the braced group. There was a significant decrease in quadriceps strength at 60°/s after BMT in the non-braced subjects (p < 0.001) while at this speed these subjects had a significantly (p =0.02) lower strength compared to their non-braced counterparts.

Conclusion: Patellofemoral bracing may be effective in preventing a decrease in quadriceps strength after prolonged strenuous training.