Isokinetics and Exercise Science - Volume 19, issue 2

Authors: Mueller, Steffen | Mayer, Patrizia | Baur, Heiner | Mayer, Frank

Article Type: Research Article

Abstract: Isokinetic dynamometry is a standard technique for strength testing and training. Nevertheless reliability and validity is limited due to inertia effects, especially for high velocities. Therefore in a first methodological approach the purpose was to evaluate a new isokinetic measurement mode including inertia compensation compared to a classic isokinetic measurement mode for single and multijoint movements at different velocities. Isokinetic maximum strength measurements were carried out in 26 healthy active subjects. Tests were performed …using classic isokinetic and new isokinetic mode in random order. Maximum torque/force, maximum movement velocity and time for acceleration were calculated. For inter-instrument agreement Bland and Altman analysis, systematic and random error was quantified. Differences between both methods were assessed (ANOVA α = 0.05). Bland and Altman analysis showed the highest agreement between the two modes for strength and velocity measurements (bias: < ± 1.1%; LOA: < 14.2%) in knee flexion/extension at slow isokinetic velocity (60°/s). Least agreement (range: bias: −67.6% ± 119.0%; LOA: 53.4%–69.3%) was observed for shoulder/arm test at high isokinetic velocity (360°/s). The Isokin_{new} mode showed higher maximum movement velocities (p<0.05). For low isokinetic velocities the new mode agrees with the classic mode. Especially at high isokinetic velocities the new isokinetic mode shows relevant benefits coupled with a possible trade-off with the force/torque measurement. In conclusion, this study offers for the first time a comparison between the 'classical' and inertia-compensated isokinetic dynamometers indicating the advantages and disadvantages associated with each individual approach, particularly as they relate to medium or high velocities in testing and training. Show more

Keywords: Strength testing, concentric, validity, trunk, knee, shoulder

DOI: 10.3233/IES-2011-0398

Citation: Isokinetics and Exercise Science, vol. 19, no. 2, pp. 63-70, 2011

Authors: Warren, Barbara L. | Wright, Kevin J.

Article Type: Research Article

Abstract: The vast majority of previous research with isokinetic machines has used only ascending or random velocity sets during testing. The purpose of this study was to investigate the effect velocity order (ascending vs. descending order) had on peak torque of knee extension during isokinetic testing and to examine the differences in peak torque in collegiate and recreational athletes. Thirty healthy, college aged males (15 collegiate athletes (CA): mean Age 20.27 yrs, Ht 178.99 cm, Mass 85.00 …kgs and 15 recreational athletes (RA): Age 21.2 yrs, Ht 183.39 cm, Mass 89.06 kgs) performed two familiarization trials and four randomly assigned experimental trials. Subjects performed four knee extension repetitions at five velocities in either ascending (60, 120, 180, 240, and 300°/sec) or descending (300, 240, 180, 120, 60°/sec) order. There was no significant (p< 0.05) difference between the order of velocities and peak torque or between CA and RA groups. Although not statistically significant, RA produced greater peak torque than CA. This may be a result of numerous RAs in this study being former collegiate athletes. In conclusion, the order of velocities may not be pertinent when establishing a protocol for testing peak torque of the knee extensors in healthy college-aged males. Show more

Keywords: Isokinetic, peak torque, knee extension, descending, ascending

DOI: 10.3233/IES-2011-0399

Citation: Isokinetics and Exercise Science, vol. 19, no. 2, pp. 71-76, 2011

Authors: Bohannon, Richard W. | Bubela, Deborah J. | Magasi, Susan R. | Gershon, Richard C

Article Type: Research Article

Abstract: If measures of muscle strength are to be broadly applied, they should be objective, portable, quick, and reliable. Through this component of the NIH Toolbox study we sought to compare the test-retest reliability of 3 tests of muscle strength that are objective, portable, and quick: the five-repetition sit-to-stand test (FRSTST), hand-grip dynamometry (HGD), and belt-stabilized hand-held dynamometry (BSHHD) of knee extension. Three sets of each test were performed- 1 warm-up and 2 maximal. Measures from the …maximal tests obtained 4 to 10 days apart were compared. Reliability was described using descriptive statistics, intraclass correlation coefficients (ICCs) and 4 measures of response stability: standard error of measurement (SEM), method error (ME), coefficient of variation of SEM (SEM_{CV} ), and coefficient of variation of variation of ME (ME_{CV} ). The ICCs of all tests were good (⩾ 0.853). Measures of response stability showed less variability between test and retest for FRSTST and HGD than for BSHHD. In conclusions all 3 tests demonstrated good test-retest reliability. However, greater differences would need to be observed between tests sessions to conclude that a real change had occurred in measures obtained by BSHHD. Show more

Keywords: Muscle strength, measurement, reliability, response stability

DOI: 10.3233/IES-2011-0400

Citation: Isokinetics and Exercise Science, vol. 19, no. 2, pp. 77-81, 2011

Authors: Ripamonti, Mickaël | Colin, Denis | Rahmani, Abderrahmane

Article Type: Research Article

Abstract: Torque-velocity and power-velocity relationships, which determine the different indicators of muscle function, have some practical application during rehabilitation program. These relationships for trunk flexor and extensor muscles during isokinetic conditions have yet to be studied in chronic lower back pain patients in order to demonstrate that maximal power could be used as a quantitative factor for this population. Ten healthy male subjects and eleven chronic lower back pain male patients performed series of isokinetic …trunk flexions and extensions at six different velocities, ranging from 45°/s to 120°/s, on a Biodex dynamometer. The torque-velocity and power-velocity relationships of trunk muscles were described by linear (P < 0.01; r=0.9–0.99) and parabolic (P < 0.05; r=0.9–0.99) relationships, respectively. Maximal power was the only parameter which showed a significant difference (P < 0.01) between the two populations for both flexor and extensor muscles. It was concluded that the lower back pain did not influence the shape of trunk muscles' torque- and power-velocity relationships. The different maximal power observed between the two groups suggests that rehabilitation program should focus on strength training for the extensor muscles whereas the flexor group would follow velocity exercise session. Show more

Keywords: Torque, power, lower back pain, rehabilitation program, trunk muscles

DOI: 10.3233/IES-2011-0401

Citation: Isokinetics and Exercise Science, vol. 19, no. 2, pp. 83-89, 2011

Authors: Edouard, Pascal | Chatard, Jean-Claude | Fourchet, François | Collado, Hervé | Degache, Francis | Leclair, Anthony | Rimaud, Diana | Calmels, Paul

Article Type: Research Article

Abstract: Background: In track and field, the load of impact, the coordination and the constraints on the ankle could result in adaptations of the ankle dynamic stabilization. These constraints could play a strengthening role and increase invertor and evertor strength also after a previous history of lateral ankle sprain. Objective: To compare the ankle invertor and evertor isokinetic strength in track and field athletes (i) with functional ankle instability (FAI), (ii) with history of lateral …ankle sprain but without functional ankle instability, and (iii) without any history of lateral ankle sprain. Methods: Twenty-five track and field athletes (5 female and 20 male, 22 ± 5 years) were included in this cross-sectional controlled study, and divided into 3 groups for comparison: (i) athletes with FAI, (ii) athletes with a previous history of lateral ankle sprain, and (iii) a control group of healthy athletes. The dominant side ankle invertor and evertor isokinetic strength were evaluated concentrically at 120 and 30°/s while the evertor strength was also tested eccentrically at 30°/s. Results: No significant differences were indicated between the muscle strength of the three groups, except for the concentric evertor peak torque and the evertor-to-invertor ratio (EIR) at 30°/s (P < 0.05). The concentric evertor peak torque and EIR at 30°/s were significantly lower in the group of athletes with a previous history of ankle sprain than in the control group (P <0.05). Conclusion: Functional ankle instability and/or history of lateral ankle sprain in track and field athletes were not associated with strength weakness of the invertor or evertor muscles. However, as the EIRs were higher than 1.0 for the healthy track and field athletes and those with FAI, it is suggested that the track and field constraints result in adaptations of the ankle dynamic stabilization and then influence invertor and evertor strength balance. Show more

Keywords: Evertor-to-invertor ratio, strength, isokinetic, peak torque, lateral ankle sprain, athletics

DOI: 10.3233/IES-2011-0402

Citation: Isokinetics and Exercise Science, vol. 19, no. 2, pp. 91-96, 2011

Authors: Caruso, J.F. | Daily, J.S. | Olson, N.M. | Shepherd, C.M. | McLagan, J.R. | Drummond, J.L. | Walker, R.H. | West, J.O.

Article Type: Research Article

Abstract: To assess the reproducibility of data collected from a newly created instrumented platform that measures vertical jump performance, healthy college-age subjects (n=178) made three visits to our laboratory. Per jump, the platform offered six performance-related variables: static weight, time to takeoff, peak takeoff force, and maximum jump heights as they ascended, remained in the air and landed. Per subject, the two highest jumps from the final two visits were used to assess data reproducibility. Prior …to the reproducibility assessment, Z-scores identified statistical outliers that were removed from subsequent analyses. Paired intra- and inter-jump session data per variable were assessed with the following statistical test-retest tools: intraclass correlation coefficients, coefficient of variation, standard error of measurement, smallest real difference and critical difference. Current results show most data had a high level of reproducibility with few exceptions. Since the platform also has potential applicability in the rehabilitation of disabled persons, future research should assess the data reproducibility associated with gait, balance and mobility collected from the device. Show more

Keywords: Force, repeatability, maximum height

DOI: 10.3233/IES-2011-0403

Citation: Isokinetics and Exercise Science, vol. 19, no. 2, pp. 97-105, 2011

Authors: Caruso, J.F. | Coday, M.A. | Mason, M.L. | Lutz, B.M. | Shepherd, C.M. | Davidson, M. | Duncan, J.J.

Article Type: Research Article

Abstract: To assess cortisol concentrations (CC) from flywheel ergometer resistive exercise, subjects performed three different leg press workouts on the device. Comprised of ten-repetition sets, the workouts entailed 1): a three-set protocol composed of concentric and eccentric actions (CE3), as well as concentric-only paradigms comprised of 2): three (CO3) and 3): six (CO6) sets. Venous blood draws, collected before workouts and at one and 30 minutes post-exercise, measured CC. ANOVA yielded CC results similar to studies that …employed standard resistive exercise equipment. However multivariate regression revealed body mass, peak angular velocity and average power were strong predictors of post-exercise CC. Separate multivariate analyses of the CE3 and pooled concentric-only (CO3 and CO6 combined) data show differences in level of explained (r^{2} ) variance, which was likely due to the ergometer's operation. Constant torque exertion throughout the CE3 bout meant performance was continual only for that workout and evoked more explained variance versus the concentric-only trials. The current ergometer was originally intended for use aboard manned spacecraft and is a prototype to newer flywheel-based resistive exercise devices. Future research should assess responses to workouts in a bed rest model to determine which protocol best abates CC to further aid future in-flight exercise. Show more

Keywords: Body mass, peak angular velocity, average power, delta lactate

DOI: 10.3233/IES-2011-0404

Citation: Isokinetics and Exercise Science, vol. 19, no. 2, pp. 107-116, 2011

Authors: McMoreland, Aidan | O'Sullivan, Kieran | Sainsbury, David | Clifford, Amanda | McCreesh, Karen

Article Type: Research Article

Abstract: Previous research has linked deficits in hip muscle strength and endurance to patellofemoral pain syndrome (PFPS). This study investigated if females with mild PFPS displayed hip isometric strength and endurance deficits compared to uninjured controls. Hip abduction, internal rotation (IR) and external rotation (ER) were assessed using an isokinetic dynamometer in 12 females with PFPS and 12 age- and gender-matched controls. Independent t-tests were used to examine between-group differences and Pearson's Correlation …Coefficient examined the relationship between isometric strength and endurance. No significant between-group differences for IR, ER and abduction strength or endurance were found (all p > 0.05). Strength and endurance measurements showed significant moderate correlations for abduction (R =0.496, p =0.014) and ER (R =0.592, p =0.002) only. The PFPS subjects had mild pain (Numerical Rating Scale: mean 1.3 cm) and disability (Anterior Knee Pain Scale: mean 81/100), which may partly explain the lack of significant between-group differences. The results suggest that female subjects with PFPS associated with mild pain and disability do not demonstrate hip IR, ER or abduction endurance or isometric strength deficits. Further research is required to clarify the role of factors including hip strength and endurance in the management of more severe PFPS. Show more

Keywords: Patellofemoral pain, strength, endurance, hip

DOI: 10.3233/IES-2011-0405

Citation: Isokinetics and Exercise Science, vol. 19, no. 2, pp. 117-125, 2011

Authors: de Marche Baldon, Rodrigo | Lobato, Daniel Ferreira Moreira | Serrão, Fábio Viadanna

Article Type: Research Article

Abstract: Muscle imbalances appear to contribute to lower limb injuries and the incidence rate of some knee injuries has been reported to be greater in females than in males. The purposes of this study were to compare the differences between genders in eccentric hip and knee peak torques normalized according to body mass as well as in eccentric hip adduction to abduction (HAD/HAB), hip medial to lateral rotation (HMR/HLR) and knee flexion to extension (KF/KE) peak …torques ratios. Seventeen males and twenty-two females participated in this study. Eccentric hip and knee peak torque for each movement were measured using an isokinetic dynamometer (Biodex Multi-Joint System 2). The Student t test for independent samples and the Mann-Whitney U test were used for all comparisons between genders (α = 0.05). The results showed that females had significantly lower eccentric hip adduction, abduction, medial rotation and lateral rotation as well as lower knee flexion and extension peak torques. Females also showed greater eccentric HAD/HAB and HMR/HLR as well as lower KF/KE peak torques ratios when compared to males. The differences verified between genders help to explain the greater rate of knee disorders observed in females. Show more

Keywords: Isokinetic, gender differences, muscle imbalance, hip, knee

DOI: 10.3233/IES-2011-0407

Citation: Isokinetics and Exercise Science, vol. 19, no. 2, pp. 127-133, 2011

Authors: Aytar, Aydan | Ozunlu, Nihan | Surenkok, Ozgur | Baltacı, Gul | Oztop, Pınar | Karatas, Metin

Article Type: Research Article

Abstract: The purpose of this randomized, double-blind study was to determine the acute effects of kinesio® taping on pain, strength, joint position sense and balance in patients with patellofemoral pain syndrome (PFPS). Twenty-two subjects with PFPS participated in the study. Subjects were separated into two groups; kinesio® taping (KT) and placebo kinesiotaping (PKT). All subjects were assessed before and 45-min after the applications. Muscle strength, joint position sense, static and dynamic balance …and pain intensity were used as the main outcome measures. Among all outcome parameters significant differences were found between strength of quadriceps muscle at 60 and 180°/s, and static and dynamic balance scores before and 45-min after application of KT. There was also a significant difference between strength of quadriceps muscle at 60°/s and static balance scores before and 45 minutes after application of the PKT. Therefore KT application does not seem to be an effective treatment method for both decreasing pain and improving joint position sense for patients with PFPS. Show more

Keywords: Balance, isokinetics, joint position sense

DOI: 10.3233/IES-2011-0413

Citation: Isokinetics and Exercise Science, vol. 19, no. 2, pp. 135-142, 2011