Isokinetics and Exercise Science - Volume 15, issue 4

Authors: Morrison, Katherine E. | Kaminski, Thomas W.

Article Type: Research Article

Abstract: The purpose of this study was to determine the reproducibility of measurements derived from a plantar flexion and dorsiflexion isokinetic test protocol. Recreationally active men (n=8) and women (n=18) were seated in 30° of trunk flexion and full knee extension (0° of knee flexion) and performed three concentric and eccentric dorsiflexion and plantar flexion movements at the speeds of 30°/s and 120°/s on two different occasions. Peak torque (PT) and average torque …(AT) measurements were obtained and compared across the two sessions. Intra-class correlation coefficient (ICC's) values indicated acceptable reproducibility for the concentric and eccentric PT and AT values of dorsiflexion (range from 0.77–0.93) and plantar flexion (range from 0.78–0.95). The corresponding Standard Error of Measurement (SEM) values indicated a good level of measurement precision. These findings suggest that this isokinetic test protocol involving an extended knee position for isolating PF and DF ankle motions produces reliable measurements. This test protocol offers a viable alternative to traditional test positions used to assess isokinetic strength in the ankle joint. Show more

Keywords: Dorsiflexion, dynamometer, plantar flexion, torque

DOI: 10.3233/IES-2007-0279

Citation: Isokinetics and Exercise Science, vol. 15, no. 4, pp. 245-251, 2007

Authors: Hazir, Tahir | Kosar, Nazan Sukran

Article Type: Research Article

Abstract: The purpose of this study was to determine gender differences in maximal anaerobic power by using both ratio scaling and allometric scaling. 27 males and 26 females voluntarily participated in this study. Wingate test was used to determine both peak power and mean power. Body weight, lean body mass and thigh muscle cross sectional area were determined anthropometrically. Males had significantly greater peak power and mean power in absolute terms, ratio-scaled and allometrically scaled to body …weight, lean body mass and thigh muscle cross sectional area (p< 0.01) compared to females. The relationships between ratio-scaled anaerobic power indices and relevant body size descriptors were significantly different from zero (p< 0.05). Ratio scaling of anaerobic power indices did not create a dimensionless index as the relationships between ratio-scaled anaerobic power indices and relevant body size descriptors are different from zero. On the other hand, relationships between allometrically scaled anaerobic power indices and relevant body size descriptors approached to zero indicating more dimensionless index compared to ratio scaling. Therefore, allometric analysis should be considered as a method to account for the influence of body size in intergroup and gender comparisons of anaerobic power. Furthermore, we have found significant gender differences in allometrically normalized anaerobic power indicating that other factors in addition to body dimensions accounts for the gender differences in anaerobic power. This result suggests that no method is perfect in accounting for gender differences in anaerobic power and thus physical performance studies of males and females should be conducted seperately. Show more

Keywords: Peak power, mean power, ratio scaling, allometric scaling, Wingate test

DOI: 10.3233/IES-2007-0281

Citation: Isokinetics and Exercise Science, vol. 15, no. 4, pp. 253-261, 2007

Authors: Holmbäck, Anna Maria | Lexell, Jan

Article Type: Research Article

Abstract: The aim of this study was to determine the test-retest (two occasions seven days part) reproducibility of isokinetic (Biodex) concentric (CON) and eccentric (ECC) ankle dorsiflexor strength and fatigue measurements in older subjects using several statistical methods. Thirty healthy men (n=15) and women (n=15) aged between 70 and 85 years participated in the study. To determine the reproducibility of strength measurements, the 30 individuals performed three maximal CON and ECC contractions at 30°/s and …90°/s. The intraclass correlation coefficient (ICC_{2.1} ) for CON and ECC strength measurements was high and ranged from 0.94 to 0.98. Bland & Altman graphs and analyses indicted no systematic bias. The standard error of measurement (SEM), representing the smallest change that indicates a real improvement (or deterioration) for a group of individuals, was small (< 2.3 Nm). The smallest real difference (SRD), representing the smallest detectable change that indicates a real improvement (or deterioration) for a single subject, was also small ('error bands' from −7.2 Nm to 5.6 Nm). A high correlation (Pearson's r > 0.94) between CON peak torque at 30°/s and 90°/s, as well as ECC peak torque at 30°/s and 90°/s, suggested that any of these two velocities could be used as a reference. To determine the reproducibility of fatigue measurements, 28 of the 30 individuals performed 50 maximal CON contractions at 60°/s. Reproducibility of the loss in work (work fatigue) and the relative loss in peak torque, comparing the first three to the last three contractions (3-3), was determined and the ICC was 0.71 and 0.60, respectively. In addition, the SEM was small (< 8.4%) and the 'error bands' to define the SRD for a single subject were also small (from −23.5% to 24.5%). In conclusion, these values indicate small measurement errors and thus provide a clinically acceptable basis for testing ankle dorsiflexion strength and fatigue of the dominant side in healthy older people. Show more

Keywords: Aging, ankle, muscle strength, muscle fatigue, reproducibility of results

DOI: 10.3233/IES-2007-0282

Citation: Isokinetics and Exercise Science, vol. 15, no. 4, pp. 263-270, 2007

Authors: Horvais, Nicolas | Samozino, Pierre | Zameziati, Karim | Hautier, Christophe | Hintzy, Frederique

Article Type: Research Article

Abstract: This study analysed muscular, mechanical and physiological parameters using a circular chainring (CC) and a non circular Osymetric chainring (OC). OC was characterized by the use of a lower radius during top and bottom dead center and a higher radius during downstroke and upstroke phases. Twelve triathletes performed (i) an 8 min submaximal test and (ii) two 8 s maximal sprint tests. Gross efficiency was calculated during the submaximal test. Instantaneous external force and …pedalling rate were recorded and the instantaneous net crank torque was calculated during both tests. Lower limb muscles coordination pattern (timing and magnitude) were also recorded. During the submaximal test, the only significant differences were the lower net crank torque of OC vs. CC at 0° and 180° and the higher net crank torque of OC vs. CC at 90° (P< 0.05). Concerning the sprint test, the only significant difference was the higher burst duration of the biceps femoris muscle with OC (P< 0.05). Present results indicate that OC facilitated mechanically the foot path at 0° and 180°. Nevertheless, this mechanical effect did not seem to be sufficient to improve performance since the muscles coordination pattern was not modified. Show more

Keywords: Chainring, performance, EMG, force

DOI: 10.3233/IES-2007-0283

Citation: Isokinetics and Exercise Science, vol. 15, no. 4, pp. 271-279, 2007

Authors: Denadai, Benedito Sérgio | Greco, Camila Coelho | Tufik, Sergio | de Mello, Marco Túlio

Article Type: Research Article

Abstract: The objective of this study was to examine the effects of high intensity exhaustive running exercise on the muscular torque capacity of the knee extensors for two types of contraction (concentric and eccentric) at different angular velocities (60 and 180°/s) in well-trained runners. Eleven male runners specialized in middle and long-distance running volunteered to participate in this study. Initially each subject performed, on different days, two familiarization sessions on an isokinetic dynamometer …and an incremental treadmill test to volitional exhaustion to determine the velocity associated with the onset of blood lactate accumulation (OBLA). The subjects then returned to the laboratory on two occasions, separated by at least seven days, to perform maximal isokinetic knee contractions at each of the velocities under eccentric (Ecc) and concentric (Con) conditions. Conducted randomly, one test was performed after a standardized warm-up period of 5 min at 50% VO_2 max. The other test was performed 15 min after continuous running at OBLA until volitional exhaustion. Following this high intensity exercise there was a significant reduction of Con at 60°/s and a significant reduction of Ecc at both velocities. Percent strength losses after running exercise were significantly different between contraction types only at 180°/s. We can conclude that the reduction in isokinetic peak torque of the knee extensors after a session of high intensity exhaustive running exercise at OBLA depends on the contraction type and angular velocity. Show more

Keywords: Concentric, eccentric, angular velocity, aerobic exercise, fatigue

DOI: 10.3233/IES-2007-0284

Citation: Isokinetics and Exercise Science, vol. 15, no. 4, pp. 281-285, 2007

Authors: van Cingel, Robert | Kleinrensink, Gert Jan | Mulder, Paul | de Bie, Rob | Kuipers, Harm

Article Type: Research Article

Abstract: Nine male and seven female asymptomatic elite badminton players were tested bilaterally to determine concentric and eccentric strength values, conventional ratio and dynamic control ratio of shoulder rotator muscles. All tests were performed at 60 and 120°/sec. The study shows significant differences that were similar for men and women: the dominant arm was stronger than the non-dominant arm, normalised peak torque values at 60°/sec were higher than at 120°/sec, the concentric internal rotator strength …(IRS) was larger than the concentric external rotator strength (ERS) and the eccentric ERS was larger than the concentric ERS. For females the eccentric ERS was larger than the concentric IRS as opposed to men in whom the concentric IRS was larger than the eccentric ERS. For both sexes the CVR for the dominant arm was significantly higher than for the non-dominant arm. The DCR at 60°/sec was significantly lower than at 120°/sec and the DCR for females was significantly higher than for men. Data presented are important for interpreting isokinetic shoulder rotator strength tests in elite badminton players and could be relevant in rehabilitation and prevention of shoulder injuries. Show more

Keywords: Isokinetics, badminton, shoulder, dynamic control ratio, conventional ratio

DOI: 10.3233/IES-2007-0285

Citation: Isokinetics and Exercise Science, vol. 15, no. 4, pp. 287-293, 2007

Authors: Müller, Steffen | Baur, Heiner | König, Timo | Hirschmüller, Anja | Mayer, Frank

Article Type: Research Article

Abstract: The purpose of this study was to analyse the reproducibility of isokinetic single-joint (knee and ankle) and multi-joint (leg-press configuration) strength findings in healthy athletes and a group of athletes with chronic unilateral tendon injuries at the lower limb, over a clinically meaningful time interval of 8 weeks. Concentric and eccentric strength performance capacity of knee extensors/flexors, ankle dorsi-/plantarflexors as well as the extensors of the total lower limb was assessed twice in 19 healthy …(H) and 10 injured (I) athletes. Calculation of ICC, standard error of measurement SEM, Bland and Altman's 95% limits of agreement and Test-Retest Variability (TRV) served as main outcome variables. The results showed a small systematic bias and random error [mean bias: 3.25 ± 4.02 (H) 4.25 ± 4.56 (I); TRV 12.34 ± 10.20% (H) 14.27 ± 9.42% (I)] except for plantarflexion measurements and the eccentric mode of the total lower limb strength in injured athletes (TRV � 20%). The present findings delineate clinically relevant cutoff values in the evaluation of valid intervention effects of strength training and rehabilitation in healthy athletes and athletes suffering from tendon-related injuries. Show more

Keywords: Isokinetics, reproducibility, injured subjects, multijoint

DOI: 10.3233/IES-2007-0286

Citation: Isokinetics and Exercise Science, vol. 15, no. 4, pp. 295-302, 2007

Authors: Olmo, J. | Aguado, J.P. | Cortés, L. | Espiniella, A. | Morate, F.

Article Type: Research Article

Abstract: Patellofemoral pain (PFP) appears in actions that increase patellofemoral compressive forces such as forceful quadriceps contraction in a flexed knee position. PFP has been associated with quadriceps strength decrease and disturbances ('breaks') in the torque-angular position. Twenty two active high-level soccer players with PFP and breaks in the quadriceps isokinetic curve were studied. The results showed that the quadriceps strength was significantly reduced in comparison with the uninvolved side, being more affected …at flexed angles of the knee. A single break in the quadriceps torque-angular position curve started on average at 73 ± 7° reaching the maximum break at 65 ± 7° and recovering at 54 ± 9°. At the minimal within-break torque angle the average reduction was 30.6% while the PT was reduced by 18.4%. Sub-clinical PFP in high-level soccer players may be related to a significant loss in quadriceps muscular performance in the first part of knee extension possibly affecting common soccer tasks such as kicking, jumping or tackling. Isokinetic concentric testing may be used to detect and characterize this alteration. Show more

Keywords: Knee, patellofemoral pain, quadriceps, isokinetic

DOI: 10.3233/IES-2007-0287

Citation: Isokinetics and Exercise Science, vol. 15, no. 4, pp. 303-307, 2007

Authors: Ahmadi, Sirous | Sinclair, Peter J. | Davis, Glen M.

Article Type: Research Article

Abstract: 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. Show more

Keywords: Oxygen saturation, blood flow, creatine kinase, myoglobin, near infrared spectroscopy, maximum voluntary contraction

DOI: 10.3233/IES-2007-0288

Citation: Isokinetics and Exercise Science, vol. 15, no. 4, pp. 309-319, 2007