Isokinetics and Exercise Science - Volume 15, issue 3

Authors: Germanou, E. | Beneka, A. | Malliou, P. | Tsiganos, G. | Papalexandris, St. | Bikos, Ch. | Godolias, G.

Article Type: Research Article

Abstract: 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. Show more

Keywords: Osteoarthritis, reproducibility, isokinetic strength, knee muscles

DOI: 10.3233/IES-2007-0261

Citation: Isokinetics and Exercise Science, vol. 15, no. 3, pp. 151-164, 2007

Authors: Baur, Heiner | Hirschmüller, Anja | Müller, Steffen | Gollhofer, Albert | Mayer, Frank

Article Type: Research Article

Abstract: It still remains unclear whether muscular activity on the treadmill (T) differs compared to overground (O) running. The purpose of this study was therefore to examine possible differences in muscular activation between T and O. 14 healthy runners were analyzed in a neutral running shoe at 12 km·h^{-1} on a treadmill and in a field test. Muscular activity (EMG) of the tibialis anterior, peroneus longus, and soleus were measured. Time and amplitude quantities were …assessed during the gait cycle. The EMG of the peroneus longus exhibited a later onset, a later maximum and shorter total time of activation (p<0.05) in O. The soleus showed a higher amplitudes in O during the push-off phase (p<0.05). Altered peroneus longus activity may indicate its role as an ankle stabilizer and demonstrates a compensatory response due to changing mechanical conditions. Weaker amplitudes of the soleus in the push-off during T suggest adaptation to the movement of the treadmill belt, and/or changes in load receptor input. Differences in muscle activity between T and O running must thus be taken into consideration in studies of neuromuscular control of movement. Show more

Keywords: Electromyography, motor control, overground running, treadmill running

DOI: 10.3233/IES-2007-0262

Citation: Isokinetics and Exercise Science, vol. 15, no. 3, pp. 165-171, 2007

Authors: Julienne, R. | Gauthier, A. | Moussay, S. | Davenne, D.

Article Type: Research Article

Abstract: The purpose of this study was to explore the effects of intensive tennis practice on the mechanical and electromyographic (EMG) activity of the external (ER) and internal (IR) rotators of the shoulder. Isokinetic and EMG testing of tennis (T, N=8) and control (C, N=8) subjects was performed using a CYBEX NORM. Shoulder rotation strength was measured at 5 angular velocities: concentric 60, 180, 300 and eccentric 60 and 180°/s during which peak torque (PT) and EMG …activity of the infraspinatus (ER) and pectoralis major (IR) was recorded. For the T group dominant side (DS) the ER/IR ratio was lower than the non dominant side (NDS) whereas no such difference was observed between DS and NDS of C group. No ERecc/IRcon ratio difference was observed between sides and groups. ER co-activation in the T group was greater in the DS compared to the NDS and the DS of C group, while values were the same for both sides of C group. It therefore seems that tennis players present an adaptation to their activity. However their mechanical and EMG values deviate quite sharply from standard values which may potentially account for injury. Show more

Keywords: Tennis, isokinetic, co-activation, shoulder rotation

DOI: 10.3233/IES-2007-0263

Citation: Isokinetics and Exercise Science, vol. 15, no. 3, pp. 173-182, 2007

Authors: McIntire, Kevin | Asher, Marc | Burton, Douglas | Liu, Hongzeng | Liu, Wen

Article Type: Research Article

Abstract: 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. Show more

Keywords: Trunk rotational strength, quantitative measurement, spinal muscles, reliability, strength ratios, strength asymmetry

DOI: 10.3233/IES-2007-0272

Citation: Isokinetics and Exercise Science, vol. 15, no. 3, pp. 183-194, 2007

Authors: Forthomme, B. | Crielaard, J.M. | Forthomme, L. | Croisier, J.L.

Article Type: Research Article

Abstract: 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. Show more

Keywords: Javelin throwers, isokinetic, shoulder, field performance

DOI: 10.3233/IES-2007-0273

Citation: Isokinetics and Exercise Science, vol. 15, no. 3, pp. 195-202, 2007

Authors: Requena, B. | Gapeyeva, H. | Ereline, J. | Pääsuke, M.

Article Type: Research Article

Abstract: The aim of the present study was to examine the acute effect of a brief submaximal percutaneous electrical stimulation (PES) of the knee extensor (KE) muscles as a conditioning activity on the isokinetic peak torque (PT) and average power (AP). Eighteen male students aged 20–25 years performed maximal voluntary concentric isokinetic knee extensions at angular velocities of 60 and 180°/s in control (CON) trial (without prior PES application), followed by a PES trial after 30 min …rest period. In PES trial, a conditioning submaximal (25% of the maximal voluntary isometric contraction force) isometric tetanic contraction of the KE muscles was induced by a 7 s direct PES at 100 Hz, interspersed after 3 min with testing of voluntary isokinetic performance. No significant differences in isokinetic knee extension PT and AP were observed between PES and CON trial at 60°/s. However, a significantly greater (p < 0.05) isokinetic PT (8.9%) and AP (8.2%) were observed in PES trial compared to CON trial at 180°/s. In conclusion, application of a brief high-frequency submaximal PES may enhance isokinetic strength and power of the KE at a moderate but not at a low angular velocity. Show more

Keywords: Electrical stimulation, knee extensors, isokinetic strength, posttetanic potentiation

DOI: 10.3233/IES-2007-0274

Citation: Isokinetics and Exercise Science, vol. 15, no. 3, pp. 203-209, 2007

Authors: Schweizer, A. | Furrer, M.

Article Type: Research Article

Abstract: The aim of the study was to determine whether forearm muscle strength correlates with sport climbing performance. Three different movements of the forearm musculature in 25 recreational climbers (performance on sight (os) style mean F7a+, range 6b+ – 7c; red point (rp) style 7b+, range 7a – 8b+) were examined. A special isokinetic device was built to investigate eccentric and concentric isokinetic maximum strength of wrist (wr) flexion, proximal interphalangeal joint (pi) …flexion of the middle- and ringfinger and a "rolling in a bar" movement involving both interphalangeal joints and the metacarpophalangeal joint (ro) of all fingers. There was no correlation between absolute maximum strength and climbing performance. Relative strength (strength/body weight) of all three exercises however correlated significantly with climbing difficulty of rp and os style, except pi flexion and os style. Correlation coefficient was highest between rp and concentric wr flexion. Among forearm musculature concentric wrist flexion was the best predictor for sport climbing performance. Show more

Keywords: Sport climbing, finger flexor, wrist flexor, maximum strength

DOI: 10.3233/IES-2007-0275

Citation: Isokinetics and Exercise Science, vol. 15, no. 3, pp. 211-216, 2007

Authors: Krauss, I. | Grau, S. | Rombach, S. | Janssen, P. | Maiwald, C. | Axmann, D. | Horstmann, T.

Article Type: Research Article

Abstract: Muscle weakness and muscle imbalance may lead to musculotendinous injuries since the energy absorption capacity of the affected muscle tendon unit is reduced. The purpose of this study was to investigate the maximum strength and strength endurance of the thigh musculature in healthy female runners (F: n=26) and female runners suffering from patellar tendinopathy (PT: n=20). Isokinetic strength measurements were recorded in a seated position. Primary outcome variables were maximum concentric …and eccentric peak torque (at 60°/s) and concentric hamstrings-quadriceps-quotient (HQQ). Secondary outcome variables were relative peak torques [Nm/kilogram] and eccentric endurance quotient calculated as the ratio of muscle strength at the end of a 1-minute exercise compared to at the beginning of the exercise period. The primary outcome variables were analyzed using Student's t-test for each measure (α = 0.05). Secondary outcome variables were qualified descriptively. The results showed no statistically significant differences between injured and healthy female runners in concentric and eccentric peak torque or HQQ. Secondary outcome variables also failed to show inter-group differences. We therefore conclude that these variables are not relevant with respect to PT in female runners. Show more

Keywords: Peak torque, strength endurance, HQQ, running, women, patellar tendinopathy

DOI: 10.3233/IES-2007-0276

Citation: Isokinetics and Exercise Science, vol. 15, no. 3, pp. 217-223, 2007

Authors: Abdalla, Sala | McGregor, Alison H. | Strutton, Paul H.

Article Type: Research Article

Abstract: 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. Show more

Keywords: Fatigue, torque, EMG, back extensors, isokinetic

DOI: 10.3233/IES-2007-0277

Citation: Isokinetics and Exercise Science, vol. 15, no. 3, pp. 225-231, 2007

Authors: Nunes, Terence | Coetzee, Ben

Article Type: Research Article

Abstract: The purposes of this study were to determine which of the isokinetic knee and shoulder strength parameters discriminate between successful and less successful provincial academy cricket batsmen and to assess the contribution of isokinetic knee and shoulder strength parameters to the performance of these athletes. Twenty-two contracted batsmen (20.63 ± 1.62 years) from the Gauteng and North-West Cricket Academies in South Africa were tested during the 2004 and 2005 seasons. The discriminant analyses showed that no …strength, work or power parameters discriminated significantly between the successful (top 5 ranked batsmen of both seasons) and less successful academy batsmen. A forward stepwise multiple regression analyses showed that the contribution of individual knee-related isokinetic parameters ranged 4–16% whereas for the shoulder the range was 4–28%. However knee parameters accounted for a total of 57% of the difference between the more and less successful batsmen while the corresponding share in terms of shoulder parameters was even higher: 61%. The conclusion that can, therefore, be drawn is that isokinetic knee and shoulder strength parameters contribute to the performance of provincial academy cricket batsmen and that these components should be included in the talent identification protocols for young promising batsmen. Show more

Keywords: Cricket, isokinetic strength, batsmen, batting

DOI: 10.3233/IES-2007-0278

Citation: Isokinetics and Exercise Science, vol. 15, no. 3, pp. 233-244, 2007