The Effects Of Rest Interval On Quadriceps Torque During An Isokinetic Testing Protocol In Elderly (original) (raw)
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An Adequate Interset Rest Period for Strength Recovery During a Common Isokinetic Test
Journal of Strength and Conditioning Research, 2013
Isokinetic testing is used in rehabilitation settings on a regular basis; yet, there is a lack of consistency in rest period usage among protocols. Furthermore, the allotment of rest periods has been arbitrary (e.g., 30, 60, 90 seconds or more). This investigation examines the work:rest ratio as an effective method of standardizing rest periods in isokinetic testing. The purpose of this study was to establish an adequate rest period that would allow reproducibility of strength during a common isokinetic strength test. Twenty-seven healthy college-aged men (age, 23 6 3.8 years; body weight, 79.54 6 11.09 kg) were tested on 5 separate occasions: 2 familiarization sessions and 3 experimental sessions. Each subject performed a knee extension/flexion isokinetic strength protocol (Cybex NORM; Lumex, Inc., Ronkonkoma, NY, USA) to determine peak torque by performing 5 maximal reciprocal repetitions at each ascending velocity of 60, 180, and 3008$s 21. Work:rest ratios of 1:3, 1:8, and 1:12 were counterbalanced between sets. A 3 3 3 repeated measures analysis of variance was used to analyze the data. A significance level of a # 0.05 was used for all tests. There was no significant difference in either knee extension or knee flexion peak torque when comparing work:rest ratios. These findings suggest that a 1:3 work:rest ratio is sufficient during a common isokinetic strength test.
Effects of Age and Rest Interval on Strength Recovery
International Journal of Sports Medicine, 2010
• ▶ muscle fatigue • ▶ aging • ▶ resistance exercise • ▶ isokinetic Eff ects of Age and Rest Interval on Strength Recovery exercise. Several studies have reported that the muscle of older adults is more fatigue resistant than younger adults [4, 5, 13, 16, 20] , and others have reported greater fatigue resistance in young adults [1, 2, 31]. Such inconsistencies may be due to the variables used to quantify fatigue during the exercise protocols (e. g., number of sets, number of reps, contraction velocity, rest between sets) as well as diff erent populations used (e. g., age, gender, and physical activity level). To date, only one study has compared the eff ect of varied RI between exercise sets in active younger and older women [32]. It has been reported that they required similar rest intervals between sets to fully recover isokinetic knee extension mean torque. However, these results may not be applied to untrained subjects or men [13]. We are currently unaware of any published studies comparing the infl uence of rest interval recovery on the performance of younger and older men in isokinetic exercises. Thus, the purpose of this study was to compare the eff ect of two diff erent RI duration between sets of isokinetic knee extension exercise on peak torque (PT), and total work (TW) in untrained young and old men.
Isokinetic assessment of knee flexor/extensor muscular strength in elderly women
Revista do Hospital das Clínicas, 2002
OBJECTIVE: To assess knee flexor-extensor muscular strength in elderly women with no previous history of musculoskeletal disorders on the lower limbs using an isokinetic dynamometer, in order to obtain data that could be used as a comparative parameter in the evaluation of elderly women with knee disorders, thus facilitating a better rehabilitation of these patients. METHODS: Twenty-six volunteers aged 75 to 83 years were studied using a Cybex® 6000 isokinetic dynamometer. The chosen angular velocity was 60 º/s, and concentric exercise was used for either flexion or extension. The studied parameters were: peak torque, angle of peak torque, and flexor-extensor torque rate. RESULTS: There were no differences between dominant (D) and nondominant (ND) knee peak torque values. This was true for both flexor (D = 42.46 ± 9.09 Nm / ND = 40.65 ± 9.38 Nm) and extensor (D = 76.92 ± 13.97 Nm / ND = 77.65 ± 15.21 Nm) movements. The descriptive statistical analysis of the values obtained for the ...
Isokinetics and Exercise Science
Effect of isotonic and isometric knee extension exercises on mechanical and electromyographical specificity of fatigue. Isokinetics and Exercise Science , 10:167-175 ***Note: Figures may be missing from this format of the document Abstract.: This study investigated the effects of isotonic and isometric knee extension exercises on strength, power, and surface EMG in male and female populations. Using the knee extensors, ten males and ten females performed a 120 s MVIC and 120 maximal isotonic contractions. Prior to each exercise (t = pre) knee extensor isometric peak torque (strength) and average peak power (power) were tested utilizing three, 3 s MVIC's and three maximal isotonic contractions, respectively. Following each exercise, strength and power were assessed immediately after (t =: 00) and at 2.5 (t =: 02.5), 5 (t =: 05), 10 (t =: 10), and 15 (t =: 15) minutes. All strength and power measures were normalized to the respective t = pre value. Vastus lateralis surface EMG signals were collected during all muscle testing and normalized to the respective tire value. Following isometric exercise, both strength and power at t =: 00 (68.7% ± 8.7% & 88.0% ± 8.7%) and t =: 02.5 (82.2% ± 17.8% & 95.2% ± 5.0%) significantly decreased from t=pre (100% ± 0.0%) (p < 0.05) with greater decreases in strength at each time point (p < 0.05). EMG analysis revealed a significant EMG amplitude decrease (p < 0.05) at t =: 00 and t =: 02.5 during strength testing with respect to t=pre. Following isotonic exercise, both strength and power at t =: 00 (68.0% ± 13.2% & 38.8% ± 10.7%) and t =: 02.5 (84.5% ± 14.9% & 81.6% ± 14.5%) significantly decreased from t=pre (100% ± 0.0%) with a greater power decrease at t =: 00 (p < 0.05). The EMG amplitude of males was significantly less at t =: 00 than the respective EMG amplitude for females (p < 0.05) (irrespective of testing condition). We conclude that muscle performance in the fatigued state is dependent upon the type of exercise performed. Article: INTRODUCTION: During the past years of research addressing muscle performance during and following fatiguing exercise, the isometric contraction has been considered the gold standard of muscle force producing capability in the laboratory setting. The muscle force production values acquired from isometric contractions are often referred to as "strength" [11]. However in sporting activities the majority of muscle contractions are dynamic in nature. Power, a variable that takes into account contraction force and velocity, is important in sports that demand explosive movements. Throughout the remainder of this paper strength will refer to isometric torque production and power will refer to dynamic, maximal efforts of the muscle/joint complex.
Isokinetic quadriceps peak torque, average power and total work at different angular knee velocities
Isokinetic dynamometry offers distinct advantages, both clinically and for research, in the evaluation and treatment of muscle performance .previous research has reported a high level of correlation between peak torque and work and between peak torque and power in the muscles surrounding normal and selected pathological knees. No research to date has examined whether such similarities exist in clients with no pathology to the knee in elderly with certain testing conditions. The purpose of this study was to investigate the relationship between the isokinetic parameters of peak torque PT, work, and power for the extensor muscle groups of elderly female. The main aim was to ascertain how the angular velocity can affect the relation between peak torque, average power and total work. Subjects, materials and methods: Isokinetic data were collected from 60 females; mean age 68.6 years on a Biodex isokinetic testing and training dynamometer at the speeds of 60, and°180, /sec. suggest that peak torque is representative of work and power and may be the only necessary parameter for isokinetic muscle performance testing of the extensor muscles of the knee in elderly.
Influence of recovery time on strength during a testing protocol of knee
Journal de Traumatologie du Sport, 2016
The aim of the present study was to compare the influence of three rest intervals of 30, 60 and 180 seconds randomly applied between two sets of five isokinetic contractions of flexor-extensor knee muscles in a cohort composed of 14 men (32.5 ± 8 years). The comparison of the isokinetic values measured during the first set of each evaluation session showed no significant differences (0.55 < P < 0.80). The analysis of the time and rest interval interaction demonstrated no significant difference between the isokinetic measures obtained after the rest intervals for peak torque of the quadriceps and of the hamstrings and for the mean power of the quadriceps and the hamstrings. These findings raise questions about a strict energetic approach and a future research should analyze the interaction of force production and fatigue phenomena in relation to the rest interval.
European Journal of Applied Physiology and Occupational Physiology, 1989
Six sedentary students, six orienteers, and six soccer players were each subjected to 15 tests, comprising 120 s of repeated, maximal isokinetic knee extensions. The tests differed with respect to movement velocity (30 degrees.s-1, 120 degrees.s-1, and 300 degrees.s-1), and movement frequency (5 at each velocity). At a certain velocity, a rectilinear relationship was found between muscular performance intensity (expressed either as average power output or as exercise time ratio) and development of fatigue (expressed either as an absolute or as a fractional decline in work output). Significant inter-velocity differences existed between the slopes of these lines at some combinations of performance and fatigue expressions. Only tendencies towards a difference in x-intercept values were found. This x-intercept value can be taken as a measure of the greatest attainable intensity level of performance without the development of fatigue. This suggestion is valuable both in basic physiological research, and as a possible criterion for optimization of muscular performance. At a given exercise time ratio, increasing movement velocity produced increasing fatigue. However, at a given muscular power output--above 15 W approximately--fatigue developed to a greater extent at the low velocity than at the two higher ones, which did not differ significantly. Substantial individual variation was seen in the positions of the low-, medium-, and high-velocity lines. These variations did not depend on the training background. This implies that the validity of using single-velocity, single-frequency tests in determining isokinetic endurance is doubtful.
Effects of different isokinetic knee extension warm-up protocols on muscle performance
The Journal of sports medicine and physical fitness
Aim: The optimal warm-up protocol for isokinetic strength performance assessment remains unclear. Therefore, the purpose of this study was to analyze the effects of different warm-up routines on strength production in young adults. Methods: Fifteen healthy young men (24.8±3.5 years) were exposed to five different isokinetic warm-up protocols. Isokinetic strength was assessed after each protocol at 60°.s-1. The warm-up protocols were: (1) submaximal, 10 submaximal consecutive repetitions (50% of maximum effort) at 60°.s-1; (2) intermittent, one set of 10 maximal intermittent contractions (30 s between contractions) at 60°.s-1; (3) 180, 10 maximal consecutive repetitions at 180°.s-1; (4) 300, 10 maximal consecutive repetitions at 300°.s-1 and (5) control session (no warm-up). Results: Peak torque was greater (P<0.05) after the intermittent (295.3±53.2 N.m) when compared to 300 (267.5±47.3 N.m) and 180 (275.2±48.6 N.m) warm-up protocols. Also, peak torque was higher (P<0.05) in t...
The effect of three different training programs in elderly women's isokinetic strength
Motricidade, 2020
This study aimed was to assess the effects of three different training protocols in quadriceps and hamstrings isokinetic muscle strength of independent elderly women. Eighty women were recruited for this study and divided into four groups of twenty subjects: the control group, the multi-component group, the muscle power group, and the muscular resistance strength group. The isokinetic strength was measured in both lower limbs with a dynamometer at 60°/s and 180o/s. The multivariate analysis (ANOVA) and the Bonferroni test assessed the group and time effect. Significant and positive effects were observed in the time and group interaction in the power group at 180°/s and 60°/s knee flexion in the dominant (p = 0.004, respectively) and non-dominant (p = 0.046 and p = 0.041, respectively) lower limbs. The Control group had significant and negative effect on the time x group interaction at 180°/s and 60°/s on the extension of the dominant knee (p = 0.008 and p = 0.001, respectively) and ...
ECCENTRIC TORQUE-PRODUCING CAPACITY IS INFLUENCED BY MUSCLE LENGTH IN OLDER HEALTHY ADULTS
Journal of Strength and Conditioning Research, 2016
Considering the importance of muscle strength to functional capacity in the elderly, the study investigated the effects of age on isokinetic performance and torque production as a function of muscle length. Eleven younger (24.2 6 2.9 years) and 16 older men (62.7 6 2.5 years) were subjected to concentric and eccentric isokinetic knee extension/flexion at 60 and 1208$s 21 through a functional range of motion. The older group presented lower peak torque (in newton-meters) than the young group for both isokinetic contraction types (age effect, p , 0.001). Peak torque deficits in the older group were near 30 and 29% for concentric and eccentric contraction, respectively. Concentric peak torque was lower at 1208$s 21 than at 608$s 21 for both groups (angular velocity effect, p , 0.001). Eccentric knee extension torque was the only exercise tested that showed an interaction effect between age and muscle length (p , 0.001), which suggested different torque responses to the muscle length between groups. Compared with the young group, the eccentric knee extension torque was 22-56% lower in the older group, with the deficits being lower in the shortened muscle length (22-27%) and higher (33-56%) in the stretched muscle length. In older men, the production of eccentric knee strength seems to be dependent on the muscle length. At more stretched positions, older subjects lose the capacity to generate eccentric knee extension torque. More studies are needed to assess the mechanisms involved in eccentric strength preservation with aging and its relationship with muscle length.