Isokinetics and Exercise Science - Volume 17, issue 4

Authors: Materko, Wollner | Santos, Edil Luis

Article Type: Research Article

Abstract: The goal of the present study was to determine and validate a model for predicting one maximum repetition (1RM) based on a submaximal strength test and the arm circumference for bench press (BP). Thirty-five male experienced in strength training underwent an anthropometric evaluation, followed by an 1RM and a 10RM test for BP. The 1RM workload was modeled through the 10RM test and the arm circumference using multiple linear regression. The model resulted in 86% of …explained variance and a 6.0% standard error of estimate of the measured 1RM for BP. The measured 1RM was 121.3 ± 18.8 kg and predicted 1RM was 120.6 ± 17.2 kg, with 0.6 ± 7.4 kg (p< 0.01) difference between obtained and predicted 1RM. The obtained model showed an acceptable reliability, and further can be currently used as a tool for predicting the 1RM workload. Show more

Keywords: Strength, 1RM, prediction model

DOI: 10.3233/IES-2009-0353

Citation: Isokinetics and Exercise Science, vol. 17, no. 4, pp. 189-195, 2009

Authors: LaRoche, Dain P.

Article Type: Research Article

Abstract: The purpose of the study was to identify both demographic and neuromuscular traits that characterize successful or unsuccessful adaptation to resistance training in older ± women. Twelve, older women underwent electrically evoked muscle twitches for the knee extensors; and performed maximal, voluntary, isometric knee extensions, followed by eight weeks of resistance training. Prior to training nonresponders had 67% higher twitch peak torque than responders (0.29 ± 0.05 vs. 0.18 ±0.06 Nm·kg^{-1} …respectively), 64% higher twitch rate of torque development (RTD) (3.96 ± 0.47 vs. 2.42 ± 0.62 Nm·s^{-1} ·kg^{-1} ), 51% higher voluntary peak torque (1.86 ± 0.40 vs. 1.23 ± 0.33 Nm·kg^{-1} ), 101% greater RTD (9.43 ±1.52 vs. 4.70 ± 2.40 Nm·s^{-1} ·kg^{-1} ), 86% greater impulse (0.13 ± 0.01 vs. 0.07 ± 0.03 Nm·s·kg^{-1} ) and 27% faster motor time (80 ± 13 vs. 109 ± 34 ms), (all P < 0.05). Following training, responders showed an 11% increase in twitch peak torque over baseline (0.18 ± 0.06 to 0.20 ± 0.05 Nm·kg^{-1} ), 15% increase in voluntary peak torque (1.23 ± 0.33 to 1.41 ± 0.36 Nm·kg^{-1} ), 47% increase in RTD (4.70 ± 2.40 to 6.93 ± 2.02 Nm·s^{-1} ·kg^{-1} ), 43% increase in impulse (0.07 ± 0.03 to 0.10 ± 0.04 Nm·s·kg^{-1} ), and 26% increase in rate of EMG rise (886 ± 214 to 1116 ± 102% pEMG·s^{-1} ) (all P < 0.05). Initially higher muscle mass and contractility, coupled with greater neural drive, likely explains why older women with good muscle performance seem to have a lower capacity for improvement than women with low initial levels of performance. Show more

Keywords: Electromyography, aging, training adaptations, strength, power, nervous activation, reaction time

DOI: 10.3233/IES-2009-0354

Citation: Isokinetics and Exercise Science, vol. 17, no. 4, pp. 197-205, 2009

Authors: Bottaro, Martim | Veloso, João | de Salles, Belmiro Freitas | Simão, Roberto | Celes, Rodrigo | Brown, Lee E.

Article Type: Research Article

Abstract: The purpose of this study was to determine the effect of single sets vs. multiple sets on different muscle groups peak torque (PT) in untrained subjects. Twenty four untrained males were randomly assigned into one of two groups: 1) knee extension three sets and elbow flexion single set (3K-1E; n = 11), or 2) knee extension single set and elbow flexion three sets (1K-3E; n = 13). Subjects trained 2 days/week for 6 weeks and each workout consisted of 1 …leg press exercise and 1 barbell curl. Training intensity started at 8 repetition maximum (RM). Strength was expressed as a concentric PT at 60°/s. ANOVA revealed that the increase in PT of the knee extensors from week 0 to 6 was significantly greater in the 3K-1E group (11.5%) than in the 1K-3E (4.0%) group, while no difference existed in the PT gains of the elbow flexors between 3K-1E (9.2%) and 1K-3E (7.8%). It was concluded that performing three sets of strength training is superior to one set for increasing strength of the knee extensors while single-set training protocols for the elbow flexors might be sufficient for untrained individuals in the early phases of a strength-training program. Show more

Keywords: Training volume, upper body, lower body, muscle strength, resistance training

DOI: 10.3233/IES-2009-0355

Citation: Isokinetics and Exercise Science, vol. 17, no. 4, pp. 207-212, 2009

Authors: Houweling, Taco A.W. | Head, Andrew | Hamzeh, Maher A.

Article Type: Research Article

Abstract: The purpose of this study was to determine the most accurate isokinetic testing method, either concentric/concentric or concentric/eccentric, for the detection of previous hamstring injury. Twenty-one male semi-professional soccer players were recruited from premier divisions of the Sunday football league and the Isthmian league division one in England and examined on a Cybex Norm isokinetic dynamometer. Eleven players had suffered previous hamstring injury whilst ten players that had never suffered hamstring injury …formed the control group. For each group the following ratios were determined: unilaterally: concentric hamstring/concentric quadriceps, eccentric hamstring/concentric quadriceps; bilaterally: concentric hamstring, eccentric hamstring and concentric quadriceps at both 60°/s and 120°/s. The Area Under the Curve (AUC) of Receiver Operating Characteristics (ROC) provided a summary measure of the validity of each test. Significant differences between injury and non-injury groups were found for the bilateral concentric hamstring ratio measured with a concentric/concentric testing method at 60°/s (AUC = 0.773, P< 0.05). All other ratios rendered non-significant AUC values. In addition, non-significant AUC were recorded for all ratios measured at 120°/s. Therefore, these observations suggested that the concentric/concentric testing method may be suitable for detecting previous hamstring injury. In addition, these findings suggested that a lower speed (60°/s) should be utilized for the muscular strength analysis of soccer players suffering from hamstring injury. Show more

Keywords: ROC analysis, hamstring injury detection, DCR, validity, accuracy, Receiver Operating Characteristics, isokinetic testing, soccer testing

DOI: 10.3233/IES-2009-0356

Citation: Isokinetics and Exercise Science, vol. 17, no. 4, pp. 213-220, 2009

Authors: Bohannon, Richard W.

Article Type: Research Article

Abstract: This retrospective work was undertaken to investigate the responsiveness of hand-held dynamometry (HHD). Potentially relevant research was identified via computerized searches of PubMed and Web of Science as well as a hand-search. Thirteen articles were found that allowed the description of responsiveness using effect size. Seventy-nine effect sizes ranged from 0 to 1.360. By Cohen's criteria most effect sizes (57%) qualified as small. Fifteen effect sizes (19.0%) qualified as medium and nine …effect sizes (11.4%) qualified as large. HHD appears capable to detecting changes in limb muscle strength that accompany interventions or are associated with the natural course of disease states. Show more

Keywords: Muscle strength, dynamometry, measurement

DOI: 10.3233/IES-2009-0357

Citation: Isokinetics and Exercise Science, vol. 17, no. 4, pp. 221-225, 2009

Authors: Denis, Romain | Korff, Thomas

Article Type: Research Article

Abstract: The mechanisms underlying age-related differences in maximum power production during multi-joint exercises are not fully understood. One factor that could contribute to these age-related differences is a differential development of the ability to generate maximum strength and power across the involved joints. Therefore, the purpose of this study was to investigate the age-related changes in knee extensor and plantarflexor strength under isometric and isokinetic conditions. Ten boys (11.6 ± 0.8 yrs) and …10~male adults (27.7 ± 5 yrs) participated in the study. Ankle plantarflexion and knee extension strength were measured isometrically and isokinetically at 30, 75 and 120°/s. Muscle activity (EMG) from the Gastrocnemius Medialis and Vastus Lateralis was also recorded. Multivariate analyses of variance identified significant Age by Joint interactions for isometric peak torque (PT) and isokinetic peak joint powers for all conditions (p<0.05). Effect sizes revealed that under isometric conditions, the difference between peak plantarflexor and knee extensor torques was moderate in children, whilst in adults, this effect was large. Under isokinetic conditions, the effect sizes describing the differences between peak joint powers produced at the ankle and knee joints were large for both children and adults. A MANOVA revealed that the Age by Muscle interaction for the magnitude of muscle activity was non-significant (p> 0.05). Our results suggest that the development of lower limb isometric strength is joint-dependent and that this joint dependence is not due to a muscle-specific development of motor unit recruitment. Show more

Keywords: Ankle, knee, torque, electromyography

DOI: 10.3233/IES-2009-0358

Citation: Isokinetics and Exercise Science, vol. 17, no. 4, pp. 227-232, 2009

Authors: Juárez, Daniel | González-Ravé, José M. | Navarro, Fernando

Article Type: Research Article

Abstract: The aim of this study was to evaluate and to compare the effects of a complex training program and a conventional training program, on power and strength development in sport science students. Sixteen undergraduates were randomly divided into two equivalent groups: Complex Training Group (CPG; n=8) and Conventional Training Group (CVG, n=8), both of which completed a similar volume and intensity of training. CPG combined maximum strength exercises with power exercises using the complex training method. …Subjects comprising the CVG group performed similarly to their CPG counterparts in the first four weeks and the equivalent power training during the second half of the program. Both programs produced gains in the weight lifted (p<0.01) 1RM back squat and the Squat Jump (p< 0.01). CPG subjects achieved gains in Maximum Strength, the Counter Movement Jump (p< 0.01), and 10, 15 and 20-m runs (p< 0.05) whereas CVG subjects achieved improvements in the 5-m run (p< 0.05). After detraining, CPG subjects experienced a decline in the Counter Movement Jump and in the 10-m run (p< 0.05). Complex and non-complex training programs in untrained subjects may increase the power and maximum strength, and generally result in improvement of these parameters without any one program showing appreciable advantages over the other. Show more

Keywords: Periodization, loads, force production

DOI: 10.3233/IES-2009-0359

Citation: Isokinetics and Exercise Science, vol. 17, no. 4, pp. 233-241, 2009

Authors: Caruso, John | McLagan, Jessica | Shepherd, Catherine | Olson, Nathan | Taylor, Skyler | Gilliland, Lauren | Kline, Dustin | Detwiler, Alex | Griswold, Shawn

Article Type: Research Article

Abstract: To assess the extent anthropometry predicts front squat performance, American college football players (n=18) performed 3–6 repetition sets at 55, 65, 75 and 80% of their 1RM (one repetition maximum) load across two workouts. At the conclusion of sets, an accelerometer (Myotest Inc., Royal Oak MI) measured peak power, force and velocity. Before the first workout, anthropometric data were collected from subjects that emphasized body segment length ratios in an attempt to predict front squat variance. …Via multivariate regression, anthropometry attempted to predict the variance from each of 12 criterion variables (peak power, force and velocity at each load). With an α=0.05, anthropometry predicted significant amounts of variance for six criterion variables, which also had high R (0.647–0.832) and R^{2} (0.419–0.720) values. The same variables also yielded moderate standard error of estimates, thus anthropometry accounted for much front squat performance variance. Height/hip width ratio, body weight, body mass index and torso length were the best predictors of front squat performance. Based on current results, it was concluded anthropometry is an important predictor of front squat performance in American college football players. Show more

Keywords: Height/hip width ratio, body weight, body mass index, torso length

DOI: 10.3233/IES-2009-0360

Citation: Isokinetics and Exercise Science, vol. 17, no. 4, pp. 243-251, 2009

Article Type: Correction

Abstract: Erratum to https://dx.doi.org/10.3233/IES-2009-0344

DOI: 10.3233/IES-2009-0364

Citation: Isokinetics and Exercise Science, vol. 17, no. 4, pp. 253-253, 2009