Isokinetics and Exercise Science - Volume 15, issue 2

Authors: Philippou, A. | Bogdanis, G.C. | Maridaki, M.

Article Type: Research Article

Abstract: This study investigated the hypothesis that isotonic muscle performance following mild muscle damage would be disproportionately affected when measured at different parts of the range of motion. Seven male volunteers performed 50 maximal isometric contractions with the elbow flexors at a lengthened position. Maximal isotonic performance was measured before and for four days post-exercise at two parts of the range of motion of elbow flexion, including mainly the descending (L) or the ascending limb (S) of …the angle–force curve. On day 1 post-exercise, muscle damage was evidenced by a decrease in peak isometric force (−20.3 ± 2.7%, p<0.01), a shift in optimum angle for force generation towards a greater elbow angle (by 0.12 ± 0.03 rad, p<0.05), and an increase in serum creatine kinase activity and muscle soreness (P<0.01). Isotonic performance indices were decreased only in the S condition (p<0.01). Shift in optimum angle and isotonic performance indices recovered on day 2. The disproportionate decrease in isotonic performance in the S condition may be explained by the shift of the optimum angle towards a longer muscle length, which would benefit force generation at elbow angles beyond the optimum angle but impair force at the more acute elbow angles. Show more

Keywords: Kinematics, length-tension curve, long muscle length, isotonic force, optimum angle

DOI: 10.3233/IES-2007-0252

Citation: Isokinetics and Exercise Science, vol. 15, no. 2, pp. 69-75, 2007

Authors: Bohannon, Richard W. | Shove, Megan E. | Barreca, Susan R. | Masters, Lisa M. | Sigouin, Christopher S.

Article Type: Research Article

Abstract: The 5-repetition sit-to-stand (STS) test is a widely used, but insufficiently evaluated, test for lower limb strength. We therefore described STS test times for a sample of community-dwelling adults, examined the association of age, gender, height, weight, and body mass index (BMI) with STS time, and determined the relationship of STS time with self-reported physical functioning. Ninety-four community dwelling adults participated. Repeated measures of STS time were reliable (intraclass correlation coefficient =0.957). …The mean STS time for all 94 subjects was 7.6 seconds. Age, weight, and BMI were (r=0.281–0.528), but gender and height were not (r=−0.074–0.007), correlated significantly with STS time. Regression analysis showed that age and BMI explained 43.7 percent of the variance in STS time. The correlation between STS time and physical functioning r=−0.474) was significant (p<0.001). Regression analysis showed that age and BMI added slightly to the explanation of variance in physical functioning provided by STS time. In conclusion, this study provides STS times that might be useful for interpreting performance of adults screened with the test. Such performance should be considered in light of age and BMI. The relationship of STS time with physical functioning provides evidence of the validity of the measure. Show more

Keywords: Muscle, strength, screening test, reliability, validity

DOI: 10.3233/IES-2007-0253

Citation: Isokinetics and Exercise Science, vol. 15, no. 2, pp. 77-81, 2007

Authors: Ostermeier, Sven | Stein, Christian | Hurschler, Christof | Windhagen, Henning | Stukenborg-Colsman, Christina

Article Type: Research Article

Abstract: Background: The objective of this study was to investigate dynamically the load on the cruciate ligaments and the effect of simulated co-contraction of the hamstrings muscles on quadriceps force and load on the cruciate ligaments. Methods: Load transducers were fixed in the fibers of the anterior and posterior cruciate ligament of seven knee specimens. Isokinetic extension motions applying an extension moment of 31 Nm, representing an extension moment capable by healthy human volunteers in …isokinetic extension tests, were simulated in a knee simulator from 120° to full knee extension. Quadriceps force and load on the cruciate ligaments were measured in the absence and presence of a 200 N hamstrings co-contraction. Results: Quadriceps force significantly (p=0.04) increased under the application of hamstrings co-contraction. Anterior cruciate ligament load significantly increased below 20° knee flexion up to 161 N and was significantly (p=0.04) reduced to 29 N under hamstrings co-contraction at full knee extension. Posterior cruciate ligament load without hamstrings co-contraction showed a maximum load at 112° knee flexion of 38 N, reducing to knee extension and was not significantly increased (p=0.20) under hamstrings co-contraction, showing a maximum load of 66 N near knee flexion. Conclusions: This dynamic in vitro study revealed the dependency of anterior cruciate ligament load on knee flexion angle during an isokinetic extension cycle. With a co-contraction of hamstring muscles the peak load on the anterior cruciate ligament was significantly decreased in knee extension with a non significant concomitant increase of posterior cruciate load at knee flexion. These findings have implications for graft donor site selection and postoperative rehabilitation, e.g. after anterior cruciate ligament reconstructions. Show more

Keywords: Knee, anterior cruciate ligament, posterior cruciate ligament, quadriceps, hamstrings

DOI: 10.3233/IES-2007-0254

Citation: Isokinetics and Exercise Science, vol. 15, no. 2, pp. 83-90, 2007

Authors: Crowther, Alexander | McGregor, Alison H. | Strutton, Paul H.

Article Type: Research Article

Abstract: Muscle fatigue has high relevance in human performance and may contribute to the high incidence of back pain amongst athletes. However, the term fatigue is often poorly defined and is used inconsistently, frequently being interchanged with endurance. This study aimed to establish whether the Biering-Sorensen test and a test of fatigue for the abdominal muscles were effective at inducing fatigue using a well established definition. Twenty medical students were subjected to two protocols (A & B). …Using a Cybex norm isokinetic dynamometer, the isometric peak torques during extension and flexion were measured before and after each protocol. Protocol A involved a 45 second maximal isometric contraction within the dynamometer while Protocol B entailed a Biering-Sorensen (submaximal) test for extension and a sit up crunch for flexion. Extension testing followed flexion testing. Significant reduction in peak mean torque occurred only in flexion for both protocols. The Biering-Sorensen test did not result in a decrease in peak torque suggesting minimal fatigue (using the definition used in this study). A weak correlation was found between the length of time the Biering-Sorensen test was held and the fatigue index. The Biering-Sorensen test does not appear to reduce maximum voluntary contraction strength and remains a test of endurance. However, a similar test for the abdominal muscles did induce fatigue. Further research is required to develop an effective protocol to assess trunk extensor fatigue. Show more

Keywords: Dynamometry, isokinetic, isometric, fatigue, endurance, back pain

DOI: 10.3233/IES-2007-0255

Citation: Isokinetics and Exercise Science, vol. 15, no. 2, pp. 91-97, 2007

Authors: Dervišević, Edvin | Hadžić, Vedran | Burger, Helena

Article Type: Research Article

Abstract: Background. Back strength is an important factor in the functional assessment of chronic low back patients and therefore ensuring the reproducibility of the findings is of critical importance. So far the studies were focusing on relative indices that turned out to be an inappropriate method due to possibility of bias. Furthermore the reproducibility of eccentric trunk flexors strength findings that may play a role in numerous sport activities has never been evaluated. Objective. To …evaluate the reproducibility of isokinetic eccentric and concentric strength of the trunk flexors and extensors in healthy subjects using the absolute reproducibility indices. Methods. Twenty seven young healthy physical education male students were tested twice over a period of one week using an isokinetic dynamometer. The main outcome measure was isokinetic peak torque. Results. Strength scores of the trunk flexors and extensors evidenced clinically acceptable reproducibility. This conclusion was valid irrespective of the testing velocity or type of contraction. Conclusion. Concentricand eccentric isokinetic testing of the trunk flexors and extensors muscles is a viable option for the testing of healthy subjects. Show more

Keywords: Isokinetics, trunk strength testing, reproducibility

DOI: 10.3233/IES-2007-0256

Citation: Isokinetics and Exercise Science, vol. 15, no. 2, pp. 99-109, 2007

Authors: Boyar, Alaaddin | Salci, Yasar | Kocak, Settar | Korkusuz, Feza

Article Type: Research Article

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

Keywords: Shoulder, proprioception, body positions, tennis

DOI: 10.3233/IES-2007-0257

Citation: Isokinetics and Exercise Science, vol. 15, no. 2, pp. 111-116, 2007

Authors: Nicolas, A. | Gauthier, A. | Michaut, A. | Davenne, D.

Article Type: Research Article

Abstract: This study was conducted to describe the time-of-day effect on muscle fatigue during both intermittent concentric (CE) and eccentric (EE) exercises. A second aim was to examine whether the time of day at which the exercise was performed influenced recovery of muscle strength. Ten male subjects performed CE and EE consisting of 5 sets of 10 maximal voluntary contractions (MVC) of the elbow flexors (angular velocity: 60°/s) at two different times (06:00 h and 18:00 h). …Torque and Electromyographic activities (EMG) of the biceps brachii and triceps brachii were recorded before (Pre), during and immediately after (Post) each fatiguing task. Furthermore, strength recovery was measured 2 days (Post_{2d}) , 3 days (Post_{3d}) and 7 days (Post_{7d}) after each fatiguing task. Results showed that during CE, torque variations were greater at 18:00 h than at 06:00 h. No time-of-day effect occurred during EE. Recovery time was faster in the morning than in the evening for isometric MVC only. To conclude, unlike the case in eccentric mode, mechanisms involved in concentric muscle action appear to be time-of-day dependent, with a greater muscle capacity in the late afternoon. Also, strength recovery is greater when fatiguing exercises are performed in the early morning than in the late afternoon. Show more

Keywords: Circadian rhythm, electromyography, time recovery, maximal effort, neuromuscular efficiency

DOI: 10.3233/IES-2007-0258

Citation: Isokinetics and Exercise Science, vol. 15, no. 2, pp. 117-129, 2007

Authors: Schweizer, A. | Schneider, A. | Goehner, K.

Article Type: Research Article

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

Keywords: Rock climbing, dynamic, eccentric-concentric, strength training, finger flexor musculature

DOI: 10.3233/IES-2007-0259

Citation: Isokinetics and Exercise Science, vol. 15, no. 2, pp. 131-136, 2007

Authors: Leverrier, Céline | Molinaro, Corinne | Gauthier, Antoine

Article Type: Research Article

Abstract: The purpose of this study was to assess the reproducibility and estimation of maximal (MVC) and submaximal muscular torque. Eight volunteers performed knee extension movements on a dynamometer. After one practice session, 3 test sessions were performed at 1 and 7 day intervals. At each session, subjects performed maximally and submaximally (25, 50 and 75% during isometric (45°) and concentric actions at 90 and 300°/s. The maximal muscular torques revealed no significant …difference over the 3 test sessions. When estimating submaximal muscular torques, subjects correctly estimated torque percentages produced in the isometric action (except in the 75% MVC) and in dynamic action (except in the 90°/s, 25% MVC). As for the stability of these estimations, subjects corrected the error in concentric actions evidencing the possible involvement of efferent copy that could enable a comparison between actual and perceived performance. On the other hand, the error in isometric actions was maintained pointing out to very limited use of this contraction mode in sporting activities. Show more

Keywords: Estimation, stability, isokinetic, torque

DOI: 10.3233/IES-2007-0260

Citation: Isokinetics and Exercise Science, vol. 15, no. 2, pp. 137-142, 2007

Authors: Vanderthommen, M. | Soltani, K. | Maquet, D. | Crielaard, J.M. | Croisier, J.L.

Article Type: Research Article

Abstract: Neuromuscular electrical stimulation (ES) and passive recovery (PR) were compared in ten healthy men after a provocation exercise inducing delayed onset of muscle soreness (DOMS). The exercise consisted of 3 sets of 30 maximal eccentric contractions performed by the knee flexor muscles of the dominant leg on an isokinetic dynamometer at 60°/s angular velocity. There was an interval of 8 weeks between both bouts and the order of the recovery mode (ES or PR) was block-randomly …assigned. ES recovery consisted of a 25-min continuous and non-tetanic (5 Hz) stimulation of the hamstring muscles. Concentric and eccentric hamstrings peak torques were evaluated before and immediately after the provocation exercise, after the recovery period, as well as 24 h (d1), 48 h (d2), 72 h (d3) and 168 h (d7) after the bout. Subjective perception of muscle soreness (VAS, 0–10 a.u.) was evaluated before exercise and at d1, d2, d3 and d7. To assess the CK activity, five blood samples were drawn before exercise and at d1, d2, d3 and d7. For both recovery modes, the greatest reductions in isokinetic muscle performances were measured on d2 (66.3 ± 24.1% of initial values (ES) vs. 57.4 ± 26.5% (PR) for the concentric mode and 55.6 ± 16% (ES) vs. 53.1 ± 19.3% (PR) for the eccentric mode). d2 also corresponded to the highest painful sensations (5.4 ± 2.14 a.u. (ES) vs. 6.15 ± 2.55 a.u. (PR)). Peak activities of CK were reached on d3 (47507 ± 19973 IU/l (ES) vs. 75887 ± 41962 IU/l (PR)). Serum CK was lower with ES than PR at d3 (p⩽0.05) but all other parameters changed in a manner that was not statistically different between the two recovery protocols (p>0.05). This strong trend could be explained by an electro-induced hyperperfusion that may efficiently wash out the muscle from the cellular debris resulting from the initial injury, and hence diminish the inflammatory response and the delayed amplification of tissue damages. Show more

Keywords: Electrical stimulation, muscle recovery, isokinetic exercise, muscle damage, delayed onset muscle soreness

DOI: 10.3233/IES-2007-0280

Citation: Isokinetics and Exercise Science, vol. 15, no. 2, pp. 143-149, 2007