Isokinetics and Exercise Science - Volume 14, issue 4

Authors: Surenkok, Ozgur | Isler, Ayşe Kin | Aytar, Aydan | Gultekin, Zuhal | Akman, Mahmut N.

Article Type: Research Article

Abstract: 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. Show more

Keywords: Static balance, fatigue, lactic acid, rehabilitation

DOI: 10.3233/IES-2006-0238

Citation: Isokinetics and Exercise Science, vol. 14, no. 4, pp. 301-306, 2006

Authors: Nikolaidou, Maria-Elisavet | Rousanoglou, Elissavet N. | Bayios, Ioannis A. | Boudolos, Konstantinos D.

Article Type: Research Article

Abstract: The study examined the relationships among isokinetic, isometric and dynamic measures of the elbow extensor (EE) and elbow flexor (EF) strength, in junior throwing athletes. The isokinetic torque (T_{ISOK} ) (90, 210, 300°/s) and the isometric torque (T_{ISOM} ) (10, 40, 90°) of the EE and EF, and the maximum force (Fz_{max} ) during the push-up test were measured in tennis (TP, n=7) and handball players (HP, n=8) (13 to 16 yrs). Statistics …included 2 (Group) × 3 (Angular velocity or Joint angle) ANOVA for group differences and the Pearson coefficient (r) for the relationships between strength measures. Handball players developed higher T_{ISOK} and T_{ISOM} (p < 0.05), however, when normalized to body mass, differences were not always significant. Fz_{max} was the same between groups (p > 0.05). The angle-specificity of the strong relationships between T_{ISOK} and T_{ISOM} (p< 0.05) reflected sport specialization. All relationships between EE and EF were significant in TP (p>0.05), whereas, T_{ISOK} and T_{ISOM} relationships with Fz_{max} were significant in HP (p < 0.05). In conclusion, athletic specialization has an impact on the relationships between isokinetic, isometric and dynamic measures of elbow strength in junior tennis and handball players. Show more

Keywords: Correlation, isokinetic, isometric, push-up, tennis, handball

DOI: 10.3233/IES-2006-0239

Citation: Isokinetics and Exercise Science, vol. 14, no. 4, pp. 307-315, 2006

Authors: Demoulin, C. | Grosdent, S. | Debois, I. | Mahieu, G. | Maquet, D. | Jidovsteff, B. | Croisier, J.-L. | Crielaard, J.M. | Vanderthommen, M.

Article Type: Research Article

Abstract: The purpose of this study was to investigate the inter-session, inter-tester and inter-site reproducibility of trunk muscle strength scores in flexion, extension, lateral flexion and rotation. Ten healthy students were tested on four apparatus with a 7–10 day break between sessions. The first two sessions were identical while the other two differed either by the tester or by the site. Furthermore, 10 patients with chronic low back dysfunction (CLBD) were assessed with the four apparatus, once …only. For all tests, CV ranged from 3.4% to 7.6% and from 3.9% to 8.1% in the inter-session and inter-tester studies, respectively (p>0.05 except for inter-session reproducibility of trunk flexor strength). Peak torque (PT) was more variable from site to site with a CV ranging from 4.2% to 12.7%, particularly in extension and left lateral flexion (p< 0.05). No statistically significant difference in the strength ratios (flexion/extension, right/left lateral-flexion and right/left rotation) were found between sessions or testers (4.9% < CV < 9.7%. The inter-site reproducibility of ratios was lower. Comparison between the CLBD patients and the healthy subjects with regard to PT normalized to body weight indicated significantly decreased performance for the former except for flexion and rotation scores in males. We conclude that in the case of healthy subjects, inter-session and inter-tester trunk strength measurements derived from these devices are reproducible. The low inter-site reproducibility suggests that caution should be exercised when interpreting findings originating from different sites. The lower extension strength scores in CLBD patients test lends some validity to the system. However, further studies focusing on reproducibility and validity of this system in CLBD patients are critical before any conclusion regarding their clinical viability may be drawn. Show more

Keywords: Trunk muscles, low back pain, isometric strength test, device reliability

DOI: 10.3233/IES-2006-0240

Citation: Isokinetics and Exercise Science, vol. 14, no. 4, pp. 317-325, 2006

Authors: Williams, C.A. | Doust, J.H. | Hammond, A.

Article Type: Research Article

Abstract: 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. Show more

Keywords: Methodology, cycle ergometry, peak power, females

DOI: 10.3233/IES-2006-0244

Citation: Isokinetics and Exercise Science, vol. 14, no. 4, pp. 327-333, 2006

Authors: Kin-Isler, Ayse

Article Type: Research Article

Abstract: 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. Show more

Keywords: Circadian rhythms, Wingate test, anaerobic power, anaerobic capacity

DOI: 10.3233/IES-2006-0246

Citation: Isokinetics and Exercise Science, vol. 14, no. 4, pp. 335-340, 2006

Authors: Skrzek, Anna | Bolanowski, Marek

Article Type: Research Article

Abstract: Background: Decreased bone strength together with impaired physical efficiency followed by falls are the most important causes of osteoporotic fractures in elderly population. Objectives: To examine the influence of age on isokinetic trunk and knee flexion and extension torque properties, and to study their associations with bone mineral density in women. Material and methods: 288 women were divided into 4 age groups (40–49, 50–59, 60–69, 70–79 years). Isokinetic concentric studies of spinal …and knee extensors and flexors were carried out at 90°/s and 120°/s, for spine, and 60°/s and 180°/s for knees. Bone mineral density was measured in the proximal femur by DXA. Results: The different strength parameters (peak torque, peak torque/body mass, average torque of five repetitions) decreased and the time to reach peak torque increased with age. Some relations have been noted between these isokinetic parameters and bone mineral density. Conclusions: Age-related deterioration in strength-velocity parameters of knee and spinal muscles are co-incidental with a gradual decrease in proximal femur BMD in older women. Show more

Keywords: Ageing, isokinetics, densitometry, osteoporosis

DOI: 10.3233/IES-2006-0247

Citation: Isokinetics and Exercise Science, vol. 14, no. 4, pp. 341-347, 2006

Authors: Lamotte, M. | Fournier, F. | Vanissum, A. | van de Borne, Ph

Article Type: Research Article

Abstract: Objective. To measure the impact of different recovery periods on systolic blood pressure (SBP) and heart rate (HR) during classical resistance training (RT) modalities Background. Resistance training was introduced into rehabilitation programs to improve the efficiency of traditional training. The impact of different RT modalities on muscular performance is well known but the recovery periods between successive RT sets recommended in the literature varied between 30 s and 5 min. Method. Twenty …one healthy subjects were tested while performing a classical RT paradigm: 3 sets of 10 repetitions at 75% of 1-RM, with recovery periods of 30, 60, 90 and 120 s. Results. A recovery period of 30 or 60 s did not allow a return of SBP and HR to resting values. A progressive drift of the values was observed in the successive rests as well as in the successive efforts. A recovery period longer than 60 s (90 and 120 s) allowed a return of SBP and HR to resting values. Conclusions. A recovery period of 90 s or more between successive classical RT sets is recommended in order to avoid excessive SBP and HR elevation. Show more

Keywords: Blood pressure, heart rate, recovery period, resistive training

DOI: 10.3233/IES-2006-0248

Citation: Isokinetics and Exercise Science, vol. 14, no. 4, pp. 349-355, 2006

Authors: Zakas, Athanasios | Galazoulas, Christos | Doganis, George | Zakas, Nikolaos

Article Type: Research Article

Abstract: While athletes routinely perform warm-up and stretching exercise, it has been suggested that prolonged stretching, immediately prior to an activity, might affect negatively the force production. Fifteen professional soccer players participated in the study to examine whether a routine duration of acute static stretching may account for losses in isokinetic peak torque production. All participants performed two static stretching protocols on the rectus femoris muscle tendon unit (MTU), at different training sessions, with a …week interval. The first stretching protocol was performed four times for 15 s (4 × 15 s), and the second 32 times for 15 s (32 × 15 s). Range of motion (ROM) was determined during knee flexion, with a pendular Myrin flexometer. The peak torque of the dominant leg extensors was measured on a Cybex Norm dynamometer at 60, 90, 150, 210 and 270°/s angular velocities. The 2 × 2 analysis of variance showed that peak torque remained unchanged, following the total static stretching for 60 s in all angular velocities, while it decreased in all angular velocities, following a total static stretching for 8 minutes (p<0.001). The findings suggest that an acute static stretching exercise of short duration, as performed by soccer players, during warming up procedures, does not produce decreases in peak torque, compared to multiple stretches of an 8 minute long duration. Show more

Keywords: Flexibility, stretching duration, range of motion, isokinetic peak torque, strength loss

DOI: 10.3233/IES-2006-0249

Citation: Isokinetics and Exercise Science, vol. 14, no. 4, pp. 357-362, 2006

Authors: Nyberg, Birgitta | Granhed, Hans | Peterson, Kerstin | Piros, Christian | Svantesson, Ulla

Article Type: Research Article

Abstract: The aim of this study was to analyze long-term changes in muscle strength and jumping ability and to assess the relationship between these parameters after anterior cruciate ligament (ACL) reconstruction. Sixty-three patients (39 men) with a mean age of 30.3 years (range 19–42) who underwent an ACL reconstruction between 1990–1992 participated in the study. Quadriceps and hamstring isometric and isokinetic strength as well as one-leg hop test for distance were measured preoperatively and six months 1, …2, 3 and 10 years postoperatively. The injured leg was significantly weaker than the non-injured leg in knee extension strength on all test occasions and in knee flexion strength except at ten years. There was a strong correlation between the muscle strength tests at different speeds. The one leg hop for distance showed significant differences between the injured and non-injured leg on all test occasions. A moderate to high correlation was observed between muscle strength and jumping ability with higher values for the non-injured leg. In our study we found a persisting weakness in the quadriceps as well as jumping ability during ten years. This is an indication that it is hard to recover the preoperative functional level after an ACL reconstruction. Show more

Keywords: Knee, physiotherapy, function, ACL, rehabilitation

DOI: 10.3233/IES-2006-0250

Citation: Isokinetics and Exercise Science, vol. 14, no. 4, pp. 363-370, 2006

Authors: Caruso, J.F. | Williams, J.A. | Hari, P. | McCoy, J.D. | Coday, M.A. | Ramsey, C.A. | Capps, L.B.

Article Type: Research Article

Abstract: An exercise ergometer that employs two flywheels for inertial resistance was created to abate ankle extensor mass and strength losses incurred with space flight. Unlike other flywheel- and inertia-based devices, the ergometer imparts muscle-lengthening resistance so that the ankle extensors may perform concentric and eccentric muscle actions within a single exercise repetition. Due to the unique manner the ergometer operates and the need to quantify workout data for the development of in-flight exercise protocols, …instrumentation of the device is an important concern. After calculation of the flywheels' moment of inertia, a motor with a small rotary shaft and rubber wheel at its terminal end was mounted on the ergometer so that it stayed in contact with, and rotated concurrently with, a single flywheel. Voltage samples produced from changes in flywheel velocity were recorded on-line at 100 MHz. Exercise performance was assessed in healthy college-age subjects (n=34) across two workouts spaced one week apart. Workouts entailed two sets of ten seated calf press repetitions as subjects were instructed to exert maximal voluntary effort. Multiple test-retest measures revealed the inertial resistance ergometer, instrumented as described herein, elicits reproducible intra- and inter-workout performance data. Show more

Keywords: Flywheel, concentric, eccentric, ergometer

DOI: 10.3233/IES-2006-0251

Citation: Isokinetics and Exercise Science, vol. 14, no. 4, pp. 371-382, 2006