Isokinetics and Exercise Science - Volume 21, issue 2

Authors: Kuroda, Daisuke | Maeyama, Akira | Naito, Masatoshi | Moriyama, Shigeki | Yoshimura, Ichiro | Nakamura, Yoshinari | Kiyama, Takahiko

Article Type: Research Article

Abstract: PURPOSE: We compared the dynamic instability of dysplastic hips using a triaxial accelerometer before and after abductor muscle strengthening exercises to determine if such exercises could achieve improvements in hip pain and associated symptoms. METHODS: We evaluated 17 hips in 17 female patients with a mean age of 37 years who presented with hip joint symptoms and acetabular dysplasia. At the initial diagnosis, we used a triaxial accelerometer to measure dynamic instability of the …hip during walking. Patients were taught how and instructed to perform abductor muscle strengthening exercises for 3 months. After this time, we re-measured. we compared these values before and after exercise. RESULTS: The average abductor muscle strength improved from 104.4 ± 35.4 N to 124.3 ± 35.9 N after exercise, an improvement of approximately 16%. The overall magnitude of acceleration significantly decreased from 2.40 ± 0.34 m/s^{2} at pre-exercise to 1.82 ± 0.28 m/s^{2} at post-exercise (p < 0.0001). The VAS also significantly improved (p=0.0005). In all cases, hip joint symptoms were significantly improved by the performance of the studied abductor muscle strengthening exercises. CONCLUSIONS: Using a triaxial accelerometer, we have shown that instability of the hip during walking can be improved by abductor muscle strengthening exercises. Show more

Keywords: Adult hips, dysplastic hips, abductor muscle strengthening exercise, triaxial accelerometer

DOI: 10.3233/IES-130480

Citation: Isokinetics and Exercise Science, vol. 21, no. 2, pp. 95-100, 2013

Authors: Bampouras, Theodoros M. | Relph, Nicola S. | Orme, Duncan | Esformes, Joseph I.

Article Type: Research Article

Abstract: BACKGROUND: Portable and cost-effective accelerometers can yield instantaneous results of force, power, and velocity, with minimum set-up time to assess muscle power. However, such devices must also produce both valid and reliable data. OBJECTIVE: The current study assessed the validity and reliability of the Myotest Pro wireless accelerometer (ACC). METHODS: Thirty physically active males performed two squat jump, on two separate sessions. The jump was recorded simultaneously by a force platform …and ACC, which was attached to a barbell resting on the subjects' shoulders. Validity was determined using Pearson correlation coefficient (r) and t-test between the maximum force platform (F_{FP} ) and ACC (F_{ACC} ) force. Between session reliability of F_{ACC} , power (P_{ACC} ) and velocity (V_{ACC} ) from the ACC were assessed with t-test, intraclass correlation coefficient (ICC), and coefficient of variation (CV). RESULTS: F_{ACC} correlated highly to F_{FP} (r=0.815, p< 0.05), but there was a proportionate ratio bias of 0.81. There was no difference between sessions (p> 0.05) for any variable. High ICCs were found for all variables (F_{ACC} 0.90; P_{ACC} 0.80; V_{ACC} 0.84). Low CV was found for F_{ACC} (2.1%), P_{ACC} (3.3%) and V_{ACC} (3.2%). CONCLUSIONS: ACC is a valid and reliable tool to use for assessing barbell movement, but caution in power data interpretation is needed. Show more

Keywords: Field measurement, muscle performance, power assessment, power production, test-retest design

DOI: 10.3233/IES-130484

Citation: Isokinetics and Exercise Science, vol. 21, no. 2, pp. 101-105, 2013

Authors: da Silva, Bruna G.C. | Bottaro, Martim | Weber, Fernanda S. | Radaelli, Regis | Gaya, Anelise R. | Cardoso, Marcelo S. | Brown, Lee E. | Carregaro, Rodrigo | Pinto, Ronei S.

Article Type: Research Article

Abstract: OBJECTIVE: To determine the applicability and predictive accuracy of an isoinertial resistance machine for the assessment of hamstring/quadriceps conventional (concentric) ratio (CR). METHOD: Thirty-two resistance trained young men (23.53 ± 3.2 yrs) were tested using dedicated instruments to obtain the peak torque (PT) of the right knee extensors and flexors as well as the corresponding one repetition maximum (1RM) values. All measurements were conducted in the concentric mode. RESULTS: Significant (p< 0.05) correlations were indicated between …knee extensor and flexor PT and 1RM values (r=0.73 to 0.75), as well as between PT and 1RM CR values (r=0.65). However the isoinertial CR values (0.42 ± 0.05) were significantly (p< 0.05) greater than their isokinetic counterparts (0.36 ± 0.04). CONCLUSION: Caution should be used when comparing isoinertial CR with population-specific isokinetic normative scores. Show more

Keywords: Muscle strength dynamometers, leg muscle strength, 1-repetition maximum test, muscle balance

DOI: 10.3233/IES-130485

Citation: Isokinetics and Exercise Science, vol. 21, no. 2, pp. 107-112, 2013

Authors: Lin, Kun-Han | Huang, Yi-Ming | Tang, Wen-Tzu | Chang, Ya-Ju | Liu, Ya-Chen | Liu, Chiang

Article Type: Research Article

Abstract: BACKGROUND: Trunk muscle endurance training is used by most high school baseball or softball coaches. However, evidence demonstrating a relationship between trunk muscle endurance and batting performance is lacking. OBJECTIVE: This study aimed to establish a relationship between trunk muscle endurance and bat swing velocity in a high school baseball team. METHOD: Sixty-one high school (15–18 years old) baseball players, taken from the same team, with 6.5 ± 1.3 years of training experience, participated in the following …tests: static trunk flexion/extension endurance tests, dynamic trunk flexion/extension endurance tests and a maximum bat swing velocity test. RESULTS: Bat swing velocity showed significant low-to-moderate negative correlations with static trunk flexor endurance (P=0.001, r=−0.404), dynamic trunk flexor endurance (P=0.016, r= −0.308) and the ratio of static flexor/extensor endurance (P=0.021, r=−0.298). CONCLUSIONS: These findings support the concept that better trunk flexor endurance might not benefit batting performance. Trunk flexor endurance training should not be over-emphasized when the targeted training goal is to enhance bat swing velocity. Show more

Keywords: Hitting, core muscle, spine stabilization

DOI: 10.3233/IES-130486

Citation: Isokinetics and Exercise Science, vol. 21, no. 2, pp. 113-119, 2013

Authors: Roczniok, Robert | Maszczyk, Adam | Stanula, Arkadiusz | Czuba, Miłosz | Pietraszewski, Przemysław | Kantyka, Joanna | Starzyński, Michał

Article Type: Research Article

Abstract: OBJECTIVE: To examine the relationships between physiological and physical profiles relative to age, together with on-ice performance in order to assess their impact on the positive result of a recruitment process into an ice hockey team. OBJECTIVE: A total of 60 boys took part in the selection camps. After these camps, 22 successful players were selected to be in the ice-hockey team and create GH2 group. GH1 was a group of hockey players who had dropped …out during the selection camp (38 participants). The control group consisted of 50 participants from secondary schools. METHODS: Data were analysed using the Student t test, one-way analysis of variance (ANOVA) and Tuckey's post-hoc test. Logistic regression was used to establish the relationship between success at selection camps and predictor variables. RESULTS: Of the 22 candidates selected to the team, 17 participants had their birth dates fall within the first six months of the selection year and positively skewed (p> 0.05). Of the 22 males selected to the team, the body height of 15 subjects was above 50th percentile and of 2 participants, above 90th percentile. Body mass of 11 participants was above 50th percentile, and of 11 subjects, above 90th percentile. Ice hockey players selected to the team were taller (p< 0.05) than players in GH1 and controls. Controls showed higher % body fat than groups GH1 and GH2. Controls had a lower level of relative VO2max (ml·kg^{ - 1} ·min-1) (p< 0.05) than ice hockey players in both groups. Furthermore, controls showed a lower level of relative peak power (W·kg^{ - 1} ) than hockey players in GH1. Mean relative peak power (W·kg^{ - 1} ) in GH1 was lower (p< 0.05) than that of males in GH2 who were selected for the team. The model indicates that height and relative peak power may be predictors of a successful selection for the team. CONCLUSIONS: The present study suggests that having a birthday early in the selection year, concomitant size advantages and a high level of anaerobic power increases ice hockey players' chance of being selected for an elite ice hockey team. Therefore, in the future, one should emphasize the talented yet less physically developed persons so as not to overlook them at further stages of adolescence. Show more

Keywords: Ice-hockey, talent identification, body composition, anaerobic power, VO_{2max}

DOI: 10.3233/IES-130487

Citation: Isokinetics and Exercise Science, vol. 21, no. 2, pp. 121-127, 2013

Authors: Bohannon, Richard W. | Andrews, A. Williams | Glenney, Susan Sullivan

Article Type: Research Article

Abstract: BACKGROUND: The responsiveness of measurements obtained by hand-held dynamometry (HHD) is largely unexplored. OBJECTIVE: A secondary analysis of data from a clinical cohort of patients (N=55) admitted for inpatient rehabilitation following acute stroke was completed to determine the responsiveness of measures of lower extremity muscle strength. METHOD: The isometric strength of hip flexion, knee extension, and ankle dorsiflexion was measured bilaterally in 55 patients using HHD. Independence in bed-to-chair transfers, level ground …gait, and stair negotiation was determined using an ordinal mobility scale. All measures were obtained at admission and discharge. RESULTS: Over the course of rehabilitation muscle strength increased significantly (p⩽ 0.002) in all 3 lower limb muscle actions of both the weaker and stronger sides. Effect sizes (0.19–0.43) and standardized response means (0.45–0.79) were mostly small to moderate but tended to be greater on the weaker side than the stronger side. The minimum detectable change (95%) values ranged from 33.2 to 87.5 N and were higher on the stronger than on the weaker side. Receiver operating characteristic curve analysis for identifying minimal clinically important differences revealed cut-points between −12.9 and 52.9 Newtons for strength increases differentiating patients who did and did not demonstrate improved mobility. CONCLUSION: HHD is capable of detecting changes in lower limb strength after stroke but the responsiveness, as indicated by effect size, standardized response mean, minimum detectable change and minimal clinically importance is limited. Show more

Keywords: Stroke, strength, hand-held dynamometry, responsiveness

DOI: 10.3233/IES-130488

Citation: Isokinetics and Exercise Science, vol. 21, no. 2, pp. 129-134, 2013

Authors: Yu, Jae-Ho | Lee, Gyu-Chang

Article Type: Research Article

Abstract: BACKGROUND: A decrease in the range of internal rotation known as glenohumeral internal rotation deficit (GIRD) which caused by repetitive overhead throwing is known to take place in elite baseball players. However few attempts at studying the differences in the range of motion (ROM), muscle strength, and endurance according to the duration of the involvement of players have been made. OBJECTIVE: To investigate the difference in ROM, muscle strength, endurance of shoulder among amateur pitchers. METHOD: …Forty-two right-handed amateur pitchers in their 20 s and 30 s, with similar physical characteristics participated in the study. They were divided into three groups according to their pitching experience. Range of motion, shoulder external and internal strength and endurance and grip strength were measured and compared. RESULTS: The ROM was significantly different among the 3 groups (P< 0.05), especially with respect to external rotation, internal rotation, and external rotation on side-lying. The peak torque of the right external rotators differed significantly between 2 and 3 year experience groups (P< 0.05). Further, the peak torque and the endurance of external rotator significantly differed between dominant and non-dominant shoulders in between 1 year group and 2 years group (P< 0.05). In external rotation endurance, there were significant differences between the 1 and 2 years groups, and between the 2 and 3 years group (P< 0.05). CONCLUSIONS: In conclusion, repetitive overhead throwing for more than a year caused structural changes in shoulder joints, which were possible responsible for changes in the range of motion and decrease external rotators performance. Such changes in the shoulder could generate a pattern shift in motion and cause secondary injuries such as internal impingement syndrome. Show more

Keywords: Shoulder, range of motion, muscle strength, endurance

DOI: 10.3233/IES-130489

Citation: Isokinetics and Exercise Science, vol. 21, no. 2, pp. 135-140, 2013

Authors: Davidson, Mark E. | Shepherd, Catherine M. | Biga, James | Davison, Steve W. | Giebel, Rachel M. | Charles, Jessica L. | Learmonth, Lexis A. | Caruso, John F.

Article Type: Research Article

Abstract: Our study assessed motor unit behavior and muscle function from high-speed unilateral elbow flexor workouts. Electromyography and performance data were obtained from subjects who completed three workouts on an Impulse (Impulse Training Systems; Newnan, GA) exercise machine. Comprised of both tonic and phasic repetitions, workouts were done with three different loads (1.13, 3.4 and 6.8 kg) added to the machine. Electromyography was measured from three muscles (biceps brachii, triceps brachii, brachioradialis). Dependent …variable means, obtained as the elbow flexed and extended, were compared with 2 (tonic, phasic) x2 (men, women) x3 (1.13, 3.4 and 6.8 kg) ANOVAs, with repeated measures for repetition and load. Bonferroni's adjustment preserved family-wise error rates and t-tests served as a post-hoc. With α=0.05, several dependent variables displayed intra-repetition and -load effects. However triceps root mean square (RMS) values displayed repetition x load interactions for both elbow flexion and extension. The triceps, an elbow flexion antagonist, may act as an important joint stabilizer, particularly at faster velocities and more extended joint angles. Unlike isometric or standard low-velocity paradigms performed against heavy loads, high-speed exercise may entail a more equitable distribution among factors (motor unit recruitment, rate coding, reflex potentiation, antagonist co-contraction) responsible for current triceps RMS values. Show more

Keywords: Triceps, root mean square, brachioradialis

DOI: 10.3233/IES-130490

Citation: Isokinetics and Exercise Science, vol. 21, no. 2, pp. 141-150, 2013

Authors: Marques, Nise Ribeiro | Hallal, Camilla Zamfolini | Crozara, Luciano Fernandes | Morcelli, Mary Hellen | Karuka, Aline Harumi | Navega, Marcelo Tavella | Gonçalves, Mauro

Article Type: Research Article

Abstract: BACKGROUND: Age-related loss in lower limb strength is related with impaired mobility. However, the association between decreased lower limb strength and gait biomechanical abnormalities is unclear. %In line with this, With respect to these statements, our study aimed to compare the maximum isokinetic voluntary strength (MIVS) of hip, knee and ankle of older women with and without history of falls. Also, we correlate the strength of each group with gait biomechanics. METHODS: The MIVS …were assessed during concentric/concentric movements performed for hip, knee and ankle joints. Gait biomechanics (kinematic and electromyography) were assessed during 1-minute recorded during the volunteers walking on the treadmill at self-selected speed. Electromyographic signal was analyzed by the linear envelop after heel strike and before toe-off. The kinematic data were analyzed using the variables: step time, length and step width and ankle angle at heel strike, and hip angle at toe-off. RESULTS: In faller group, we found that a decreased hip abduction and adduction MIVS is associated with a higher tibialis anterior activation at initial stance (p =0.04 and r =−0.53 and p=0.04 and r=−0.52). CONCLUSION: Therefore, an impaired strength of hip could causes compensation in ankle stabilizer muscles activation at initial stance in older female fallers. Show more

Keywords: Aging, fall risk, torque, EMG, kinematic, walking

DOI: 10.3233/IES-130491

Citation: Isokinetics and Exercise Science, vol. 21, no. 2, pp. 151-159, 2013

Authors: Botton, Cíntia E. | Radaelli, Regis | Wilhelm, Eurico N. | Silva, Bruna G.C. | Brown, Lee E. | Pinto, Ronei S.

Article Type: Research Article

Abstract: The greater torque generation capacity of muscles when contracted alone than in combination with contralateral muscles, characterizes the bilateral limb deficit (BLD) phenomenon. Few studies have explored the BLD in dynamic movements, because isometric actions are considered ideal for evaluating strength. Therefore, the aim of this study was to compare BLD between isometric and concentric actions of the knee extensors. Eleven healthy young men (age=20.6 ± 1 yrs; weight=71.4 ± 6.4 kg; height =174.4 …± 7 cm) volunteered to participate. Initially, subjects visited the laboratory for familiarization with the test protocols. On two subsequent randomized days they performed a test protocol with either a unilateral (right and left limbs) or bilateral condition, with 48~h rest between. The test protocol was composed of five isokinetic concentric actions of the knee extensors at 60°/s and three isometric actions at a 60° angle of knee flexion. The greatest peak torque of the two conditions was used for analyses. Both muscle actions demonstrated greater values unilaterally (p< 0.05) than bilaterally and BLD values were not significantly different between them (p> 0.05). Therefore, if muscle torque production is greater unilaterally, athletes and coaches may utilize unilateral exercises to increase training loads. Show more

Keywords: Strength training, unilateral, bilateral, concentric

DOI: 10.3233/IES-130492

Citation: Isokinetics and Exercise Science, vol. 21, no. 2, pp. 161-165, 2013