Isokinetics and Exercise Science - Volume 23, issue 4

Authors: Pawel, Linek

Article Type: Research Article

Abstract: BACKGROUND: To date, an assessment of the differences in the deep abdominal muscles among adolescent volleyball players at rest and during the abdominal drawing-in maneuver (ADIM) has not been performed. OBJECTIVE: The aim of the study was to assess the thickness of the transversus abdominis (TrA) and internal oblique (OI) muscles at rest and during the ADIM in healthy adolescent volleyball players. METHODS: Ninety-two secondary school students and members of volleyball sports clubs participated in the study. Measurements of the thickness of the muscles at rest and during ADIM were made in the supine …position with ultrasound imaging. RESULTS: The TrA was thicker in the volleyball group versus controls by 0.50 mm (95% CI: 0.09-0.99; p= 0.02). The OI was thicker in the volleyball group by 1.02 mm (95% CI: 0.34-1.71; p< 0.001). The analysis of the TrA preferential activity ratio showed that it was significantly higher, by an average of 0.03 (95% CI: 0.01-0.04; p< 0.001), in the volleyball group. The TrA contraction ratio was also significantly higher in the volleyball group, by an average of 0.20 (95% CI: 0.02-0.34; p= 0.03). CONCLUSIONS: Adolescents who participate in volleyball training have higher TrA and OI thickness. The study showed higher values of the TrA preferential activation and contraction ratios in the volleyball group. Show more

Keywords: Ultrasound, lateral abdominal wall, motor activity, health, motor control

DOI: 10.3233/IES-150596

Citation: Isokinetics and Exercise Science, vol. 23, no. 4, pp. 215-220, 2015

Authors: Parmar, Prashant | Perry, Rachel | Martin, Jake | Vickers, Samantha | Baptista, Rachel | Edwards, Roman | McArtor, Jon | Mitchell, Lacey | Caruso, John

Article Type: Research Article

Abstract: BACKGROUND: To limit physiological changes incurred with space flight, exercise hardware should impart sufficient mechanical loads with minimal energy costs. OBJECTIVE: Assess net energy costs from exercise done on flywheel-based hardware. METHODS: Subjects (17 men, 19 women) performed the following leg press workouts in a randomized sequence: two sets of concentric-only (CO2) actions, two sets with both concentric and eccentric (CE2) activity, and four sets of concentric-only (CO4) actions. Workouts entailed 8-repetition sets with 90-second rest periods. O2 was measured before, during and after workouts to calculate net energy costs. Total work (TW) …was derived from flywheel rotation rates as follows: TW = (1/2)(J)(ω 2 ) whereby J = rotation inertia and ω = angular velocity. TW and net energy costs were assessed with 2(gender) × 3(workout) ANOVAs with repeated measures for workout. RESULTS: TW had significant differences by gender (men > women) and workout (CE2, CO4 > CO2). Net energy costs also yielded significant differences by gender (men > women) and workout (CO4 > CE2, CO2). CONCLUSIONS: For the CE2 workout ∼ 50% of the TW occurred through muscle lengthening. Eccentric actions should be part of workouts done on this hardware, as they impart large mechanical loads with little net energy cost. Show more

Keywords: Metabolism, eccentric, muscle lengthening, mechanical loading

DOI: 10.3233/IES-150597

Citation: Isokinetics and Exercise Science, vol. 23, no. 4, pp. 221-227, 2015

Authors: Mitchell, Lacey N. | Perry, Rachel A. | Martin, Jake L. | Vickers, Samantha D. | Baptista, Rachel A. | Clark, Ashley N. | McArtor, Jon D. | Caruso, John F.

Article Type: Research Article

Abstract: BACKGROUND: High-speed exercise is an essential training component to prepare athletes for competition. To date correlations between anthropometry and high-speed exercise performance are mixed. OBJECTIVE: To assess anthropometry as a correlate to performance from workouts comprised exclusively of tonic or phasic repetitions done on a high-speed resistive exercise device (Impulse Training Systems; Newnan, GA). METHODS: Male athletes (n = 31) did two workouts that involved performance of a standing unilateral rowing motion with their left arm for two 60-second sets. Each workout was comprised solely of tonic or phasic repetitions. Anthropometric measurements included: height, …mass, body fat percentage, shoulder width, upper and lower arm lengths as well as torso length. Mean force and total work values from each type of workout served as criterion variables. RESULTS: Anthropometry predicted significant amounts of variance for both mean force and total work values (r2 ∼ 0.21) from tonic workouts. However anthropometry failed to predict a significant amount of performance variance from phasic workouts. CONCLUSIONS: Anthropometry acts as a better correlate to high-speed resistive exercise performance for repetitions that do not terminate with impact forces and are inherently less ballistic, as the latter likely utilizes less momentum. Show more

Keywords: Tonic, phasic, ballistic, momentum

DOI: 10.3233/IES-150598

Citation: Isokinetics and Exercise Science, vol. 23, no. 4, pp. 229-235, 2015

Authors: Chu, Yungchien | Keenan, Karen | Allison, Katelyn | Lephart, Scott | Sell, Timothy

Article Type: Research Article

Abstract: BACKGROUND: Strength of body segments and bat velocity during the baseball swing have been described as positively related, but the relative importance of each body segment's strength and the effect of ball location in the strike zone have not been examined. OBJECTIVE: To identify the correlation between the strength of different body segments along the kinetic chain and bat velocity with the ball placed at different locations within the strike zone, and to determine which segment's strength best predicts bat velocity. METHODS: Nineteen adult baseball hitters were assessed for bat velocity at five ball …locations and tested for isokinetic trunk, shoulder, and knee strength. Strength variables significantly correlated to bat velocity were used in backward stepping linear regression. RESULTS: Trunk rotation strength was significantly correlated to bat velocity for all ball locations. Knee strength was significant for all locations except for high inside. Shoulder strength was significant only with the ball outside. Based on regression analysis, trunk rotation strength was the only significant predictor. CONCLUSIONS: Significant correlations between chosen strength variables and bat velocity were identified. Only trunk rotation strength was a significant predictor of bat velocity. Baseball hitters seeking greater bat velocity may benefit from targeting trunk rotation strength. Show more

Keywords: Baseball swing, isokinetic strength, bat velocity

DOI: 10.3233/IES-150583

Citation: Isokinetics and Exercise Science, vol. 23, no. 4, pp. 237-244, 2015

Authors: Hebisz, Paulina | Hebisz, Rafal | Zatoń, Marek | Borkowski, Jacek

Article Type: Research Article

Abstract: BACKGROUND: While interval training is considered an effective modality for improving physical performance, it is still unclear how to monitor and determine optimal training load. OBJECTIVE: The study aimed to identify differences in power, heart rate, and acid-base balance in response to a single interval training session in cyclists. METHODS: The research involved 21 mountain cyclists experienced and inexperienced with interval training. The interval training test consisted of several sets (4-6, until exhaustion) of maximal intensity exercise on a cycle-ergometer. Each set comprised four 30-s repetitions interspersed with 90-s recovery periods. Peak power, work …output, heart rate, hydrogen and lactate ion concentrations were measured. RESULTS: The cyclists experienced with interval training performed significantly more (p< 0.01) sets than inexperienced cyclists (5.6 ± 1.0 vs. 4.5 ± 0.8 sets, respectively). Power and work output decreased in the last completed set only in the inexperienced group (660.5 ± 53.6 vs. 659.9 ± 71.3 W and 666.6 ± 63.3 vs. 633.7 ± 86.8 W in the first and last sets for the experienced and inexperienced cyclists, respectively). The experienced group showed a decrease in hydrogen ion accumulation in the fourth set; in the inexperienced group this occurred in the second set. The experienced group showed lower heart-rate recovery times after the last set. CONCLUSIONS: Cyclists experienced with interval training could perform more repeated bouts of exercise with a disrupted acid-base balance at a similar performance level than inexperienced cyclists. Show more

Keywords: Maximal exercise, load, lactic acidosis, heart rate

DOI: 10.3233/IES-150584

Citation: Isokinetics and Exercise Science, vol. 23, no. 4, pp. 245-252, 2015

Authors: Mbada, Chidozie Emmanuel | Dedeke, Adeyemi Gabriel

Article Type: Research Article

Abstract: BACKGROUND: Flexion/extension trunk muscle endurance imbalance is more clinically significant than isolated trunk endurance deficits. OBJECTIVE: This study provides reference values and correlates of trunk flexion/extension endurance ratio among healthy young Nigerian adults. METHODS: A total of 208 volunteers participated in this study. Static Back Extensors Endurance (SBEE), Dynamic Back Extensors Endurance (DBEE), Static Abdominal Muscles' Endurance (SAME) and Dynamic Abdominal Muscles' Endurance (DAME) were assessed following standard protocols. Data was analyzed using descriptive and inferential statistics. RESULTS: The mean age, SBEE, DBEE, SAME and DAME were 22.2 ± 1.76 years, …78.3 ± 41.5 secs, 21.1 ± 9.69 reps, 39.1 ± 24.5 secs and 16.5 ± 15.8 reps respectively. Static and dynamic trunk flexion/extension endurance ratio was 0.63 ± 0.50 and 0.86 ± 0.74 respectively. There were significant differences in trunk static (0.81 ± 0.57 secs vs. 0.53 ± 0.42 secs; p= 0.001) and dynamic (1.04 ± 0.48 reps vs. 0.74 ± 0.83 reps reps; p= 0.001) flexion/extension endurance ratio in men and women, respectively. CONCLUSION: This study established a set of reference values for static and dynamic trunk flexion/extension endurance ratios among healthy young Nigerians. Men had significant higher trunk flexion/extension endurance than women. Show more

Keywords: Static endurance, dynamic endurance, flexion/extension endurance ratio, Nigerians

DOI: 10.3233/IES-150585

Citation: Isokinetics and Exercise Science, vol. 23, no. 4, pp. 253-261, 2015

Authors: Intziegianni, Konstantina | Cassel, Michael | König, Niklas | Müller, Steffen | Fröhlich, Katja | Mayer, Frank

Article Type: Research Article

Abstract: BACKGROUND : Reproducible measurements of tendon structural properties are a prerequisite for accurate diagnosis of tendon disorders and for determination of their mechanical properties. Despite the widely used application of Ultrasonography (US) in musculoskeletal assessment, its operator dependency and lack of standardization influences the consistency of the measurement. OBJECTIVE: To evaluate the intra-rater reproducibility of a standardized US method assessing the structural properties of the Achilles tendon (AT). METHODS: Sixteen asymptomatic participants were positioned prone on an isokinetic dynamometer with the knee extended and ankle at 90° flexion. US was used to assess AT-length, cross-sectional …area (CSA), and AT-elongation during isometric plantarflexion contraction. The intra-rater reproducibility was assessed by ICC (2.1), Test-Retest Variability (TRV, %), Bland-Altman analyses (Bias ± LoA [1.96*SD]), and Standard-Error of Measurement (SEM). RESULTS: Measurements of AT-length demonstrated an ICC of 0.93, TRV of 4.5 ± 3.9%, Bias ± LoA of -2.8 ± 25.0 mm and SEM of 6.6 mm. AT-CSA showed an ICC of 0.79, TRV of 8.7 ± 9.6%, Bias ± LoA of 1.7 ± 19.4 mm2 and SEM of 5.3 mm2 . AT-elongation revealed an ICC of 0.92, TRV of 12.9 ± 8.9%, Bias ± LoA of 0.3 ± 5.7 mm and SEM of 1.5 mm. CONCLUSIONS: The presented methodology allows a reproducible assessment of Achilles tendon structural properties when performed by a single rater. Show more

Keywords: Ultrasonography, Achilles tendon, reproducibility, isokinetic

DOI: 10.3233/IES-150586

Citation: Isokinetics and Exercise Science, vol. 23, no. 4, pp. 263-270, 2015

Authors: Bohannon, Richard W. | Chu, Johnson | Portz, Megan

Article Type: Research Article

Abstract: Although adequate hip extension strength is necessary for the successful performance of weight-bearing activities, practical quantitative procedures for measuring hip extension strength are lacking. We sought, therefore, to describe a practical procedure and the reliability and validity of measurements obtained with it. Apparently healthy individuals (10 men, 10 women) of 18-27 years participated. One male and one female examiner tested all subjects in supine with a hand-held dynamometer during 2 sessions, 1 week apart. Inter-tester and test-retest reliability of measurements were good to excellent (intraclass correlation coefficients = 0.827-0.949). Known groups validity was supported by a demonstration of significant differences …in the strength of men and women participants. Based on the findings of this study we can recommend the procedure for testing with other populations. Show more

Keywords: Hip, muscle, strength, testing

DOI: 10.3233/IES-150587

Citation: Isokinetics and Exercise Science, vol. 23, no. 4, pp. 271-274, 2015

Authors: Moreira, Pedro V.S. | Gonçalves, Mauro | Crozara, Luciano F. | Castro, Alex | Neto, Antônio F. Almeida | Goethel, Márcio F. | Cardozo, Adalgiso C.

Article Type: Research Article

Abstract: BACKGROUND: Hamstrings:quadriceps (H:Q) strength muscular imbalances are frequently associated with injuries. OBJECTIVE: To investigate the H:Q ratio dependencies of the fatigue effect induced by an exhaustive isokinetic exercise. METHODS: Nineteen male soccer players were evaluated, before and after exhaustive isokinetic exercises, for electromechanical delay (EMD), root mean square (RMS), median frequency (MF), and rate of electromyographic rise (RER) of the rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), semitendinosus (ST), isometric peak torque (PT) and rate of torque development (RTD) of the knee extensors (KE) and knee flexors …(KF). The fatigue effect was measured by paired dependent tests, with a significance level of p < 0.05. RESULTS: RTD and PT were reduced (23-38%), with an H:Q reduction of RTD100 ms by 21%. In PT, antagonist RMSVL and RMSRF decreased by 32-39%, but at 0-50 ms, 0-100 ms and 0-200 ms, agonist RMSRF diminished by > 32%. At 0-50 ms and 0-100 ms, the antagonist RMSVM improved by > 149%. RERRF and RERST diminished in both 0-50 ms and 0-100 ms (38-41%), while RERBF decreased at 0-50 ms (30%). Agonist MFRF and MFBF in PT decreased by 9-10%. CONCLUSION: Neuromuscular fatigue due to maximal isokinetic concentric voluntary contractions affects the hamstrings more than the quadriceps in terms of producing rapid torque. Show more

Keywords: Isokinetic, isometric contraction, torque, hamstring-quadriceps ratio, electromyography

DOI: 10.3233/IES-150588

Citation: Isokinetics and Exercise Science, vol. 23, no. 4, pp. 275-282, 2015

Authors: Porto, Jaqueline Mello | Marques, Nise Ribeiro | Junior, Renato Campos Freire | Abreu, Daniela Cristina Carvalho de

Article Type: Research Article

Abstract: BACKGROUND: The standardization of trunk-muscle strength assessment is important for clinical practice. OBJECTIVE: To compare trunk muscle strength and electromyographic (EMG) activation of the trunk and lower limb muscles during testing with and without foot support using an isokinetic dynamometer. METHODS: Trunk flexion and extension strength was evaluated in 34 young individuals using isometric and isokinetic contractions, with and without foot support. Concomitantly, EMG signals from the trunk and dominant lower limb muscles were recorded. RESULTS: With foot support, the muscle strength generated during isokinetic and isometric extension contractions was …greater than that without foot support (p < 0.001). The use of foot support enhanced the activation of trunk muscles (lumbar iliocostalis and longissimus dorsi) only during isometric extension contractions, whereas increased isokinetic extension contractions were associated with greater medial and lateral gastrocnemius activation. CONCLUSIONS: Testing trunk extension strength with foot support is recommended because it results in a higher peak moment under isometric conditions, possibly due to greater EMG activation of the trunk muscles. During isokinetic conditions, the use of foot support promoted increased extensor strength without increased EMG activation of the trunk muscles. By contrast, testing of trunk flexion strength may be conducted with or without foot support. Show more

Keywords: Muscle strength, trunk, Biodex

DOI: 10.3233/IES-150589

Citation: Isokinetics and Exercise Science, vol. 23, no. 4, pp. 283-289, 2015