Isokinetics and Exercise Science - Volume 13, issue 2

Authors: Hahn, D. | Schwirtz, A. | Huber, A.

Article Type: Research Article

Abstract: The purpose of this study is to offer standardisation of multi-articular leg extension movements for isokinetic testing, based on a two link rigid body model with equal length of thigh and shank. Such standardisation corrects interindividual variations and may enable the derivation of the force-length-velocity [F(l,v)] characteristics during multiple joint (MJ) activities.

Keywords: multiarticular leg extension, modelling, standardised kinematics

DOI: 10.3233/IES-2005-0185

Citation: Isokinetics and Exercise Science, vol. 13, no. 2, pp. 95-101, 2005

Authors: Howatson, G. | van Someren, K.A.

Article Type: Research Article

Abstract: The aim of this investigation was to examine the intra-subject and group reproducibility of isometric muscle function testing and the associated surface EMG signal repeated over five consecutive days using isokinetic dynamometry. Fifteen physically active volunteers that were unfamiliar with isokinetic dynamometry participated in this study and were asked to attend the laboratory on five consecutive days to complete maximal isometric testing. Surface electromyography was recorded from biceps brachii to examine the …electrical activity associated with the peak torque. The intra-subject reproducibility was moderate for isometric torque (mean coefficient of variation (CV) of 6.65%), however the EMG and EMG:torque ratio were somewhat more variable (mean CV of 18.20% and 18.49%, respectively). The group reproducibility showed an intra-class correlation coefficient of r = 0.99, 0.92 and 0.96 for isometric peak torque, EMG and torque: EMG ratio. In addition, the group CV for isometric peak torque, EMG and torque:EMG ratio was 1.03%, 4.10% and 3.38%, respectively. Individuals can show large variations in torque and EMG, however when reproducibility is examined as a group both torque and the associated EMG activity have high reproducibility in physically active subjects, unfamiliarised with isometric dynamometry. Show more

Keywords: reproducibility, coefficient of variation, intra-class correlation coefficient, isokinetic dynamometry, electromyography

DOI: 10.3233/IES-2005-0186

Citation: Isokinetics and Exercise Science, vol. 13, no. 2, pp. 103-109, 2005

Authors: Degache, Francis | Calmels, Paul | Garet, Martin | Barthélémy, Jean-Claude | Da Costa, Antoine | Isaaz, Karl | Costes, Frédéric | Roche, Frédéric

Article Type: Research Article

Abstract: Background: In patients with CHF, physical reconditioning improves exercise tolerance and endurance capacity. However, there is no evidence that endurance training programs affect skeletal muscle strength in such patients. Design: The present study investigates the effects of endurance training on isokinetic skeletal muscle strength and on aerobic capacity in chronic heart failure (CHF) patients. Methods: Eleven stable CHF patients (8 men, mean aged 54.3 yr and women, mean aged 49.3 yr) participated in a …classical controlled inhospital 8-week endurance training program. Progressive incremental exercise tests with gas exchange analysis and isokinetic strength measurements of knee flexors and extensors were conducted in all subjects before and after training at different angular velocities (60, 180, 240°/s ). Results: After training, peak � O_2 improved significantly (from 16.3 ± 3.3 to 20.7 ± 4.0 ml/kg/min; p < 0.002) as did New York Heart Association (NYHA) functional class (2.2 ± 0.4 to 1.5 ± 0.5; p < 0.001). Conversely, isokinetic strength at all angular velocities studied was unchanged after the training program. Conclusion: Isokinetic muscle strength was not improved in CHF patients participating in a endurance training program. A combined endurance and resistance protocol might be helpful for these patients whose frequently altered muscle strength undoubtedly contributes to their poor quality of life for everyday activities. Show more

Keywords: chronic heart failure, cardiac rehabilitation, isokinetic muscle strength

DOI: 10.3233/IES-2005-0187

Citation: Isokinetics and Exercise Science, vol. 13, no. 2, pp. 111-117, 2005

Authors: Schaubert, Karen | Bohannon, Richard W.

Article Type: Research Article

Abstract: This study focused on the reliability, differences, and error of sit-to-stand (STS) test measurements obtained during 3 sessions separated by 6 weeks. Twenty-one community-dwelling elders (65–85 years) participated. The mean times required to complete five STS repetitions at each test session were 13.2, 12.0, and 10.9 seconds. The times were reliable (intraclass correlation coefficient = 0.82) but were significantly different (F = 6.889, p = 0.003) and demonstrated a linear trend over sessions (F = 10.157, …p= 0.005). The technical error of the measurement for the times ranged from 1.7 to 2.8 seconds. Although the intraclass correlation coefficient showed the STS measurement to possess good reliability, the significant difference and trend over time suggests that subjects may experience some test familiarization with repeated performance. Given this possibility and the technical error of the measurement, clinicians should be cautious in equating small decreases in STS time to real improvement. Show more

Keywords: muscle, strength, test, sit-to-stand

DOI: 10.3233/IES-2005-0188

Citation: Isokinetics and Exercise Science, vol. 13, no. 2, pp. 119-122, 2005

Authors: Okamoto, Takanobu | Masuhara, Mitsuhiko | Ikuta, Komei

Article Type: Research Article

Abstract: We investigated the effects of eccentric contraction velocity on oxygen uptake and oxygen dynamics in the rectus femoris. Knee extension exercise was performed in 15 healthy male subjects using an isokinetic dynamometer. The angular velocity was set at 60 and 180°/s with a near infrared spectroscope probe fixed on the rectus femoris in order to record muscle oxygenation (MO) levels during and after the exercises. Oxygen uptake was measured using the breath-by-breath method. MO levels at …an angular velocity of 60°/s were significantly lower than at an angular velocity of 180°/s at 60 and 90 seconds after the onset of the exercises (p < 0.05). Oxygen uptake increased immediately after the onset of the exercises and reached the highest level at the end of the exercises at both angular velocities of 60 and 180°/s. When MO levels were the lowest (60 sec. after the onset of the exercise), oxygen uptake levels were significantly higher at an angular velocity of 60°/s versus 180°/s (p < 0.05). These results revealed that decreased MO levels at a lower muscle contraction velocity might be due to increased mechanical compression of the blood vessels resulting in impaired blood flow. In addition, low oxygen levels of active muscle may stimulate increases in oxygen uptake to avoid hypoxia. The hypoxic conditions in active muscle during the first half of the exercise was temporary, offset by the steady increase in alveolar oxygen uptake during exercise. Show more

Keywords: eccentric contraction, muscle oxygen dynamics, oxygen uptake, contraction velocity

DOI: 10.3233/IES-2005-0190

Citation: Isokinetics and Exercise Science, vol. 13, no. 2, pp. 123-128, 2005

Authors: Dugailly, P.-M. | Brassinne, E. | Pirotte, E. | Mouraux, D. | Feipel, V. | Klein, P.

Article Type: Research Article

Abstract: The purpose of this study was to assess hip muscle performance in the three anatomical planes and to assess the reproducibility of measurements using isokinetic dynamometry. Twenty-eight symptom free amateur sportsmen students (11 females, 17 males), performed three consecutive isokinetic evaluations of both hips at 60 and 120°/s. Nine male subjects performed a test-retest protocol. Reproducibility was reported using different statistical methods such as intraclass correlation coefficients, mean difference, standard error and …95% confidence intervals. Compared to the women's PT, men scored significantly higher in all velocities with the generally expected torque-velocity relationships. No dominance effect was noted. Significant differences between agonist and antagonist muscle performance were also indicated. The agonist/antagonist ratios ranged 0.74–1.48 and were significantly influenced by velocity with a significant inter-group difference at 120°/s. Results based on the test-retest paradigm indicate caution in the interpretation of the peak torque (PT). Show more

DOI: 10.3233/IES-2005-0191

Citation: Isokinetics and Exercise Science, vol. 13, no. 2, pp. 129-137, 2005

Authors: Chapman, D. | Newton, M. | Nosaka, K.

Article Type: Research Article

Abstract: This study verified the eccentric torque-velocity relationship of human elbow flexors by considering muscle damage induced in maximal eccentric torque measurements. Twenty subjects (26.4 ± 6.2 yrs) were tested twice, separated by 7 days, for maximal voluntary isometric torque at 90° (1.57 rad) of elbow flexion (ISO) and isokinetic eccentric torque (ECC) at velocities of 30°·s^{-1} followed by 90°, 150°, 210°·s^{-1} , and a repeated 30°·s^{-1} using …a range of movement from 60° to 140° (180°: full extension). ISO preceded each ECC measure to assess the effects of muscle damage and/or fatigue on the measures. The difference in ECC at 30°·s^{-1} between the first and second attempts was used to adjust the torque values. The reliability of the measurements was supported by high intra-class correlation coefficient (0.96–0.99) and low coefficient of variation (6.3–9.1%). Peak ECC at all velocities were significantly (p < 0.05) greater than ISO (14–16%), but no significant differences were evident among velocities. The second ECC at 30°·s^{-1} was significantly (p < 0.05) lower (∼10%). than the first, and ISO decreased significantly (p < 0.05) over the measurements (∼10%). Following adjustment, no significant differences in ECC torque among velocities were still evident. It is concluded that eccentric torque is approximately 15% higher than isometric torque without influence of angular velocity for the elbow flexors. Show more

Keywords: isokinetic, isometric, reliability, muscle damage

DOI: 10.3233/IES-2005-0192

Citation: Isokinetics and Exercise Science, vol. 13, no. 2, pp. 139-145, 2005

Authors: Fleming, J.C. | McGregor, A.H.

Article Type: Research Article

Abstract: Objective: To investigate the muscle strength profile of the forearm in experienced tennis players and non-tennis players, including establishment of reproducibility data for dynamometer testing of grip strength, forearm and wrist torque. Methods: Grip strength was evaluated using a mechanical handgrip dynamometer. Pronation/supination and wrist extension/flexion performance was tested using an isokinetic dynamometer. Ten subjects (mean age 22.9 ± 1.8 yrs) took part in reproducibility testing. For the main study, twelve …tennis players (mean age 24.6 ± 9.3) and twelve controls (mean age 22.2 ± 1.2) were evaluated using the same protocol. Results: Reproducibility values showed variability between testing sessions, highlighting that caution be employed when using this equipment. Average maximum grip strength of tennis players was significantly higher (p < 0.0001) in the dominant arm (51.19 kg) compared to their non-dominant arm (45.03 kg). Pronation in the dominant arm was significantly higher than the non-dominant arm in both subject groups. Wrist extension was stronger in the dominant arm compared to the non-dominant arm in both subject groups. Conclusion: Reproducibility of test protocol needs to be addressed if it is to be used in future comparative studies. This study indicates that prolonged asymmetrical sporting activity produces muscle profile asymmetries between and within limbs. The functional significance of these findings requires further investigation. Show more

Keywords: tennis, forearm, symmetry, muscle balance, isokinetic, reproducibility

DOI: 10.3233/IES-2005-0193

Citation: Isokinetics and Exercise Science, vol. 13, no. 2, pp. 147-151, 2005

Authors: Holm, Inger | Steen, Harald | Olstad, Marte

Article Type: Research Article

Abstract: Few studies have used a longitudinal design approach to evaluate the development of isokinetic performance in children. The purpose of the present study was to evaluate isokinetic muscle performance in the same cohort of normal boys from pre-teen until late maturity (based on bone age assessments). Twelve healthy boys from a local soccer team were recruited. They were tested at six various occasions from pre-puberty until maturity. The mean age at inclusion was 9.8 (9.3–10.3) years. …At each test anthropometric data (height, weight, chronological age and bone age) were collected. Isokinetic muscle function in knee flexion and extension was tested concentrically at 60 and 240°/sec. Bone age was generally retarded compared to chronological age; in average by -1.0 (-4.1.–1.7) years. There was a significant increase in absolute muscle performance values through the whole study period. When the values were normalized by body weight significant differences occurred only between test 3–4 and 4–5. This study indicates that a significant increase in muscle performance per se occurs in healthy boys during puberty, i.e. from the bone age of 12 until 17 years. Furthermore bone age does influence the development of isokinetic muscle performance but body weight is the normalizing factor that best explains the increase in performance. Show more

Keywords: isokinetic, strength development, children, maturity

DOI: 10.3233/IES-2005-0194

Citation: Isokinetics and Exercise Science, vol. 13, no. 2, pp. 153-158, 2005

Authors: Benjamin, Scott J. | Flood, J.N. | Bechtel, Roy

Article Type: Research Article

Abstract: Objective: To examine the feasibility of using isokinetic test findings as clinical outcome measures for rehabilitation success in patients following Anterior Lumbar Interbody Fusion (ALIF) surgery. Background: Literature supports isokinetic exercise for trunk flexion/extension testing and training. Despite the wide acceptance of isokinetics, there is a paucity of literature on trunk flexion/extension testing pre and post Anterior Lumbar Interbody Fusion (ALIF) surgery. Study Design: Pre-post surgical intervention Methods and Materials: Physical therapy …evaluation was conducted prior to patients' performance of isokinetic testing. If surgical criteria were met, testing occurred prior to their surgery. Once healing (fusion) was shown with radiographs, patients underwent testing after one month of regimented rehabilitation. Results: Findings indicated that all patients tolerated isokinetic testing prior to and after their ALIF surgery. Improvements of up to 50% in trunk flexion and extension peak torque were noted post-rehabilitation. Pain levels decreased from moderate to minimal during testing and did not interfere with pre- or post-testing. Conclusion: Isokinetic testing is safe, effective and not a detriment to patients who are candidates for ALIF procedure. Testing these patients will potentially aid in return to function by narrowing the scope of rehabilitation and proviing objective measures of trunk strength. Show more

Keywords: strength, stability, surgery, isokinetics

DOI: 10.3233/IES-2005-0195

Citation: Isokinetics and Exercise Science, vol. 13, no. 2, pp. 159-162, 2005