Isokinetics and Exercise Science - Volume 24, issue 1

Authors: Hill, Ethan C. | Housh, Terry J. | Camic, Clayton L. | Jenkins, Nathaniel D.M. | Smith, Cory M. | Cochrane, Kristen C. | Cramer, Joel T. | Schmidt, Richard J. | Monaghan, Molly M. | Johnson, Glen O.

Article Type: Research Article

Abstract: BACKGROUND: Previous investigations have examined the torque and neuromuscular responses to maximal concentric and isometric muscle actions. The literature, however, has paid less attention to the effects of performing maximal eccentric muscle actions. Furthermore, the available information in this regard is contradictory. OBJECTIVE: The purpose of the present investigation was to examine eccentric, isokinetic peak moment (PMe), electromyographic (EMG) amplitude (AMP), EMG mean power frequency (MPF), mechanomyographic (MMG) AMP, and MMG MPF patterns of responses to repeated, maximal, eccentric muscle actions at 60, 120, and 180°/s. METHODS: Twelve resistance-trained men visited the laboratory …on three occasions (separated by ≥ 72 h) and performed 30 repeated, maximal, eccentric muscle actions of the dominant leg extensors on an isokinetic dynamometer at randomly ordered velocities of 60, 120, and 180°/s. RESULTS: There were no changes (p > 0.05) across the 30 repeated, eccentric muscle actions for PMe, MMG AMP, and EMG MPF for any of the velocities. There were, however, increases in EMG AMP and decreases in MMG MPF for each velocity. CONCLUSIONS: The decrease in MMG MPF, which reflects the global firing rate of the activated motor units, in conjunction with the lack of change in MMG AMP, which reflects motor unit recruitment, suggested that the increase in EMG AMP was due to motor unit synchronization. Show more

Keywords: Electromyography, mechanomyography, muscle fatigue, muscle lengthening, isokinetic, motor control

DOI: 10.3233/IES-150591

Citation: Isokinetics and Exercise Science, vol. 24, no. 1, pp. 1-6, 2016

Authors: Çakır, T. | Toraman, N.F. | Uçkun, A. | Yalçın, Ü

Article Type: Research Article

Abstract: BACKGROUND: Although exercise is recommended for knee osteoarthritis, to the best of our knowledge there have been no studies comparing isometric and isokinetic exercise in relation to the degree of osteoarthritis. OBJECTIVE: To compare the effectiveness of isokinetic and isometric exercise programs in terms of pain, physical function and muscle strength in relation to the severity of knee osteoarthritis. METHOD: A total of 73 females, aged 50-65 years with bilateral Grade II (n= 36) and Grade III (n= 37) knee osteoarthritis were randomly assigned to an isokinetic [Grade II (n= 19), Grade III …(n= 18)], or isometric exercise group [Grade II (n= 17), Grade III (n= 19)]. The isokinetic groups underwent a concentric strengthening program at 90°/s and 120°/s once per day, and the isometric groups underwent an isometric strengthening program at 3 times per day for 15 days. Transcutaneous electrical nerve stimulation, ultrasound and hot packs were applied for all groups. The primary outcome measure was pain evaluated by visual analogue scale and secondary outcome measures of Western Ontario {&} McMaster Universities Osteoarthritis Index, sit-stand, standing-up from a chair and 15-m walking, ascend/descend stairs, and concentric flexor and extensor peak torque at 90, 120, 180 and 300°/s were measured in all patients before and after 15 days of treatment. RESULTS: A significant difference was determined between the isokinetic grade III group and the isometric grade III group adjusted to baseline values at 15 days post-treatment in respect of flexion peak torque value at 120°/s.The change in the peak torque value in the isokinetic grade III group was greater than that of the the isometric grade III group (108%, 59%, respectively). No statistically significant differences were found between the groups in the other outcome measures and isokinetic peak torque values at different velocities. CONCLUSION: The concentric flexion torque at 120°/s improved more in the isokinetic grade III group than in the isometric grade III group. Show more

Keywords: Knee osteoarthritis, strength training, physical function, physical therapy

DOI: 10.3233/IES-150592

Citation: Isokinetics and Exercise Science, vol. 24, no. 1, pp. 7-15, 2016

Authors: Montenegro, Rafael A. | Farinatti, Paulo T.V. | de Lima, Paulo F.M. | Okano, Alexandre H. | Menêses, Annelise L. | de Oliveira-Neto, Leônidas | Cavalcante, Bruno R. | de A. Correia, Marilia | Fontes, Eduardo B. | Ritti-Dias, Raphael M.

Article Type: Research Article

Abstract: BACKGROUND: Recent evidences have shown that the motor cortex (MC) may influence the rating of perceived exertion (RPE). Given the potential role of transcranial direct current stimulation (tDCS) in modulate cortical areas related to exercise performance, it is possible that tDCS applied on motor cortex (MC) could also influence the RPE during resistance exercises. OBJECTIVE: This study analyzed the effects of transcranial direct current stimulation on the rating of perceived exertion during multiple sets of resistance exercises. METHODS: Thirteen strength-trained men performed a resistance exercise session after either anodal tDCS or sham stimulation …applied over the primary motor cortex. Resistance exercise sessions included 3 sets of 10 repetitions of 6 exercises performed with load of at 85% of 8-12 RM. The RPE was obtained using OMNI-Resistance exercise scale. RESULTS: The RPE assessed at the end of the sessions was similar in tDCS vs. sham condition (6.78 ± 1.48 vs. 6.87 ± 1.49, respectively; p = 0.56). The RPE for each exercise was similar across conditions, except for the second set of bench press (p = 0.04) and first set of seated-row (p = 0.03). CONCLUSION: In conclusion, the RPE during multiple sets of submaximal exercises was not modulated by tDCS applied upon MC. Show more

Keywords: tDCS, motor cortex, exercise, perceived exertion, strength

DOI: 10.3233/IES-150593

Citation: Isokinetics and Exercise Science, vol. 24, no. 1, pp. 17-24, 2016

Authors: Pekünlü, Ekim | Ozkaya, Ozgur | Yapicioglu, Bulent

Article Type: Research Article

Abstract: BACKGROUND: Mathematical procedures involved in the calculation of fatigue index (FI) and power drop (PD) are the main reasons why these traditional fatigue-related indices of Wingate All-out Test (WAT) are the least reliable indices. OBJECTIVE: To suggest a highly reliable fatigue-related output calculated by drop in mechanical work production (DMW). METHODS: Twenty-one well-trained male athletes (age: 21.8 ± 1.9 years, peak power [PP]: 14.7 ± 1.3 W ⋅ kg - 1 ) participated in a series of WAT sessions, using 10% of their body mass as the workload, separated by 2-4 …days. These WAT sessions were continued until the difference in PP between successive trials was less than 5%. Traditional FI and PD values were calculated using mean power data obtained from 5, 3, 2 and 1-second time intervals and using instantaneous power data, while DMW was calculated by predetermined areas in power-time curve. RESULTS: Intraclass correlation coefficients (ICC) and coefficient of variations (CV) revealed that DMW had higher reliability level (ICC = 0.92, CV = 4.53%) than that of traditional fatigue-related indices (ICC ≤ 0.91, CV ≥ 5.71%). In addition, DMW had the lowest limit of ``real change'' with 10.2% as the minimum detectable change score at 90% confidence. CONCLUSIONS: DMW might be used as a reliable output to evaluate fatigue-related power data of the anaerobic capability. Besides, Monark Inc. may easily modify its Peak Bike 894E software to make 30-second all-out test more reliable for the assessment of fatigability levels. Show more

Keywords: Cycle ergometer, fatigue index, indices, instantaneous power, power drop

DOI: 10.3233/IES-150594

Citation: Isokinetics and Exercise Science, vol. 24, no. 1, pp. 25-31, 2016

Authors: McLeland, Kathryn A. | Ruas, Cassio V. | Arevalo, Jose A. | Bagley, James R. | Ciccone, Anthony B. | Brown, Lee E. | Coburn, Jared W. | Galpin, Andrew J. | Malyszek, Kylie K.

Article Type: Research Article

Abstract: BACKGROUND: Anaerobic fatigue is a limiting factor in performance and athletes are often tested to determine their fatigue resistance. Administering the classic Thorstensson test of fatigability is a popular method to determine fatigue percentage as it requires 50 maximal knee extension repetitions. However, there has been little research to determine whether performing more or fewer repetitions yields similar results. OBJECTIVE: The purpose of this study was to compare concentric fatigue percentage (FP) between the classic Thorstensson test (CT; average of first 3 repetitions to average of last 3 repetitions) and three different repetition ranges: peak torque …repetition to repetition 30 (P30), peak torque repetition to repetition 50 (P50), and peak torque repetition to repetition 60 (P60). METHODS: Fifteen resistance trained men (age = 24.8 ± 1.3 yrs; height = 178.9 ± 5.1 cm; mass = 82.2 ± 8.0 kg) volunteered to perform 60 maximal concentric knee extension repetitions at 180°/s on an isokinetic dynamometer, measuring peak torque of each repetition. RESULTS: P30 (r= 0.81) and P50 (r= 0.77) were highly correlated with CT but P60 (r= 0.58) was only moderately correlated with CT. P30 FP (44.7 ± 8.8) was significantly less than CT (62.3 ± 6.0), P50 (66.0 ± 6.8) and P60 (69.7 ± 7.1). CONCLUSION: FP can be determined through fewer repetitions of a knee extension fatigue test on an isokinetic dynamometer. While both P30 and P50 were highly correlated with CT, performing fewer repetitions requires less time to complete as well as less residual fatigue. When measuring knee extension FP, the number of repetitions performed in the test may be reduced to 30 while still maintaining a high correlation to a longer method of 50. Show more

Keywords: Muscle, fatigue, isokinetic dynamometer, peak torque, fatigability

DOI: 10.3233/IES-150595

Citation: Isokinetics and Exercise Science, vol. 24, no. 1, pp. 33-38, 2016

Authors: Fernandes, John F.T. | Lamb, Kevin L. | Twist, Craig

Article Type: Research Article

Abstract: BACKGROUND: The FitroDyne has been used to assess muscle function but its reproducibility has not been determined during traditional multi-jointed resistance exercises. OBJECTIVE: To assess the intra- and inter-day reproducibility of the FitroDyne during traditional resistance exercises. METHODS: Fourteen resistance trained males completed a one repetition maximum (1RM) and three repetitions of bench press, squat and bent-over-row in 10% increments (from 20 to 80%). Replica trials were completed two and 48 hours later. The FitroDyne rotary encoder measured barbell velocity during each repetition from which power output was calculated. RESULTS: …For all loads and exercises the intra-day typical error (TE) for peak and mean power, and velocity, respectively, during bench press (8.2-53 W and 2.2-6.9 cm ⋅ s - 1 ), squat (13.3-55.6 W and 2.4-7.4 cm ⋅ s - 1 ), and bent-over-row (14.5-62.8 W and 4-10.5 cm ⋅ s - 1 ) identified only moderate changes. Bench press yielded poor intra-day reproducibility at 80% 1RM only (CV% = 12.2-17.1), whereas squat and bent-over-row across all loads for peak and mean power and velocity displayed better reproducibility CV% = 2.4-9.0). Inter-day, the TE detected moderate changes for peak and mean power and velocity for all three exercises. Inter-day reproducibility was comparable to intra-day, though improved for bench press 80% 1RM (CV% = 6.1-8.6). CONCLUSION: These data support the use of the FitroDyne at submaximal loads for monitoring moderate changes in muscle function both intra- and inter-day. Show more

Keywords: Power, velocity, reliability, bench press, squat, bent-over-row

DOI: 10.3233/IES-150599

Citation: Isokinetics and Exercise Science, vol. 24, no. 1, pp. 39-49, 2016

Authors: Dunsky, Ayelet | Ben-Sira, David

Article Type: Research Article

Abstract: BACKGROUND: There is a general agreement in the physical education and coaching communities on the importance of warm-up (WU) prior to any physical performance. Nevertheless, the value of WU remains controversial among researchers. OBJECTIVE: The purpose of the study was to assess the effect of direct, indirect, and combined direct and indirect WU protocols (DWU, IDWU, and CWU, respectively) on knee extension rate of torque development (RTD). METHODS: Twenty-nine physical education students were tested for maximal isometric knee extension tests on an isokinetic machine following each of the WU protocols, as well as …following a control condition of no WU. RTD index was calculated for 50, 100, 150, and 200 ms from the initiation of knee extension for each trial. RTD values following the four protocols were compared by repeated measures ANOVA for each of the temporal indices. RESULTS: None of the differences between the protocols' means was statistically significant at any of the temporal indices. Nevertheless, individual responses demonstrated that certain participants exhibited a non-uniform response profile, thus suggesting differential responses to alternate protocols. CONCLUSIONS: Within the limitations of the current protocol and outcome measures, it is recommended that practitioners experiment with different WU routines and adjust them on an individual basis. Show more

Keywords: Direct warm-up, indirect warm-up, rate of torque development

DOI: 10.3233/IES-150600

Citation: Isokinetics and Exercise Science, vol. 24, no. 1, pp. 51-58, 2016

Authors: Zhang, Shen | Fu, Weijie | Xia, Rui | Wang, Xi

Article Type: Research Article

Abstract: BACKGROUND: The mechanism by which increased compression affects muscle strength and electromyographic (EMG) time/frequency domain behavior during prolonged muscle actions has yet to be elucidated. OBJECTIVE: To determine the effectiveness of compression on quadriceps strength and endurance and EMG amplitude/frequency of the quadriceps during repeated concentric muscle contractions. METHODS: Twelve healthy male athletes executed 25 maximal repeated isokinetic knee extensions in compression garment (CG) and control condition (CC) at 60 and 300°/s on a dynamometer. The EMG time and frequency domain behavior of the rectus femoris (RF), vastus lateralis (VL), and vastus medialis …were collected synchronously. RESULTS: Compression exerted no significant effect on peak moment and total work during the isokinetic contractions. By contrast, the overall EMG root mean square amplitude was significantly lower (p < 0.05) in CG than in CC while the EMG mean power frequency of the RF and VL was significantly higher (p < 0.05) in CG than in CC at 60°/s. CONCLUSION: The described effects may potentially improve muscle endurance and fatigue resistance during prolonged muscle actions. Show more

Keywords: Compression pressure, isokinetic muscle strength, electromyography, mean power frequency

DOI: 10.3233/IES-150601

Citation: Isokinetics and Exercise Science, vol. 24, no. 1, pp. 59-65, 2016

Authors: Crozara, Luciano F. | Morcelli, Mary H. | Hallal, Camilla Z. | Marques, Nise R. | Spinoso, Deborah H. | Goethel, Márcio F. | Vieira, Edgar R. | Gonçalves, Mauro

Article Type: Research Article

Abstract: BACKGROUND: Lower-extremity strength and neuromuscular parameters that are more affected with age and in individuals more prone to fall still needs to be identified in healthy physically active adults. OBJECTIVE: To investigate the ability of joint torque and muscle activity parameters to differentiate between physically active women, young, older non-fallers and older fallers; and their correlation with the number of falls in older women. METHODS: Measures were taken from concentric contractions during isokinetic sagittal plane movements at 90°/s and 120°/s. EMG from the rectus femoris, vastus lateralis, biceps femoris, lateral gastrocnemius and tibialis …anterior were recorded. RESULTS: Overall young women were stronger, more powerful and presented lower muscle activation than older women fallers and non-fallers (all p < 0.04). Older women fallers had lower knee flexion and extension peak torque (p < 0.033) and power (p < 0.045), lower ankle dorsiflexion power (p = 0.04) and higher rectus femoris activation (p = 0.033) at 90°/s than older women non-fallers; and all these variables were correlated with the number of falls (r = 0.32-0.49; p < 0.05). CONCLUSIONS : These findings may be useful for a better understanding of biomechanical risk factors for falls and for exercise-based fall prevention programs development. Show more

Keywords: Strength, electromyography, older adults, accidental falls

DOI: 10.3233/IES-150602

Citation: Isokinetics and Exercise Science, vol. 24, no. 1, pp. 67-77, 2016

Authors: Tsiokanos, Athanasios | Paschalis, Vassilis | Valasotiris, Konstantinos

Article Type: Research Article

Abstract: BACKGROUND: The movements that soccer players have to perform during a game depend on lower limb muscles strength and clearly players with higher strength levels are able to perform better turning, sprinting and changing pace. OBJECTIVE: To compare the isokinetic peak torque of the knee extensors in a large number of elite Greek soccer players in relation to their position on the playing field. METHODS: Two-hundred and seventy-five soccer players: goalkeepers (n= 24), fullbacks (n= 67), center backs (n= 59), midfield players (n= 76) and forwards (n= 49) from the first division in …Greece participated in this study. All participants performed an isokinetic test of the knee extensors at 30, 60 and 180°/s. RESULTS: In terms of knee extension strength the goalkeepers were the strongest while the fullbacks were the weakest players but strength normalization resulted in uniform knee extension strength irrespective of field position. CONCLUTIONS: The present findings provide a reference system for knee extension strength in soccer players. Show more

Keywords: Soccer, football, isokinetics, quadriceps, strength

DOI: 10.3233/IES-150603

Citation: Isokinetics and Exercise Science, vol. 24, no. 1, pp. 79-82, 2016