Isokinetics and Exercise Science - Volume 23, issue 1

Authors: Rocha-Júnior, Valdinar A. | Bottaro, Martim | Pereira, Maria C. | Ferreira-Júnior, João B. | Carmo, Jake | Brown, Lee E. | Nascimento, Francisco A.O.

Article Type: Research Article

Abstract: BACKGROUND: Normalization in surface electromyography (SEMG) has been the object of numerous investigations. OBJECTIVE: The purpose of this study was to evaluate the reliability of normalized SEMG amplitude, as well as the reliability of different normalization coefficients during isokinetic upper-body strength assessment. METHODS: Thirteen male subjects performed a maximal isokinetic elbow flexion test and test-retest separated by 5 to 7 days. Three normalization coefficients were extracted from the tests: 1) mean value of …the rectified SEMG signal (Mean_{Task} ); 2) peak value of the rectified SEMG signal (Peak_{Task} ); 3) maximal value of the rectified SEMG signal of the peak torque repetition (Isokinetic-spec_{MVC} ). These normalization coefficients, as well as the root mean square value (RMS) of the signal before and after normalization by described coefficients (RMS-Mean_{Task} ; RMS-Peak_{Task} ; RMS-Isokinetic-spec_{MVC ) were evaluated in terms of absolute and relative reliability. RESULTS: None of the normalization coefficients presented acceptable levels of absolute reliability (bias range in limits of agreement greater than 27%). However Mean_{Task} and Isokinetic-spec_{MVC} presented good levels of relative reliability (ICC > 0.80). RMS-Mean_{Task} was the only amplitude parameter that demonstrated satisfactory indices of absolute (bias range lower than 5% and CV < 1.50%) and relative (ICC > 0.80) reliability. CONCLUSIONS: Normalizing SEMG amplitude by Mean_{Task} is a reasonable strategy to reduce day-to-day amplitude discrepancies during isokinetic upper-body strength assessment. Show more

Keywords: Elbow flexion, reproducibility, normalization

DOI: 10.3233/IES-140558

Citation: Isokinetics and Exercise Science, vol. 23, no. 1, pp. 1-12, 2015

Authors: Ruas, Cassio V. | Pinto, Matheus D. | Brown, Lee E. | Minozzo, Felipe | Mil-Homens, Pedro | Pinto, Ronei S.

Article Type: Research Article

Abstract: BACKGROUND: The isokinetic hamstrings to quadriceps (H:Q) dynamic control ratio (DCR) is frequently used to assess muscle imbalances and to screen for potential risks of knee injuries in sports. OBJECTIVE: To investigate the correlation between knee conventional ratio (CR) and DCR in elite soccer players and check for a possible relationship. A positive correlation would indicate that the CR could predict DCR. METHODS: One hundred and thirteen Brazilian elite soccer players (25.2 ± 5.3 yrs) performed maximal dominant …and nondominant knee concentric (CON) and eccentric (ECC) strength tests at 60°/s on an isokinetic dynamometer in order to calculate CR and DCR. RESULTS: A significant positive correlation between ratios was found for the dominant and non-dominant knees (r=0.54 and 0.62; p < 0.001 which translated into low R^{2} values of 0.29 and 0.39, respectively. CONCLUSION: This suggests that the CR may not replace the DCR and is thus of a limited clinical value in assessing knee muscles imbalance. On the other hand, the paper presents for the first time a robust reference frame for the isokinetic strength and related ratios of the two major knee muscles in soccer players. Show more

Keywords: Knee imbalance, torque ratios, injury prevention, assessment accessibility

DOI: 10.3233/IES-140557

Citation: Isokinetics and Exercise Science, vol. 23, no. 1, pp. 1-12, 2015

Authors: Manca, Andrea | Pisanu, Francesco | Ortu, Enzo | De Natale, Edoardo | Ginatempo, Francesca | Dragone, Daniele | Leali, Paolo Tranquilli | Deriu, Franca

Article Type: Research Article

Abstract: BACKGROUND: To our knowledge, no studies on foot drop (FD) caused by peripheral nerve lesion have investigated whether unilateral training of the unaffected ankle dorsiflexors induced a clinically meaningful strength improvement in the affected-untrained leg, namely a cross-training (CT) effect. METHOD: A 59-year-old man, who suffered since childhood from surgically-induced damage of the common peroneal nerve, performed an 8-week maximal-intensity isokinetic training of the healthy leg. Before and after training, …patient underwent: bilateral isokinetic testing; functional and mobility tests including 6-minute walking test, 10-meter walking test, timed-up-and-go test and ankle ROM; neurophysiological recordings including motor thresholds, cortical silent period of the hemisphere innervating the affected tibialis anterior and mean EMG recruitment. RESULTS: After cross-training, the affected-untrained dorsiflexors showed notable increases in all dynamometric parameters. Similarly, all functional tests improved considerably. The cortical silent period was reduced and the maximal EMG recruitment increased. CONCLUSIONS: Improvements in muscle performance and neurophysiological drive in the affected non-trained limb due to training of the unaffected side indicate that cross-training may be a viable rehabilitative approach to foot drop. Show more

Keywords: Isokinetic testing, training, transfer, peripheral nerve injury, transcranial magnetic stimulation

DOI: 10.3233/IES-140559

Citation: Isokinetics and Exercise Science, vol. 23, no. 1, pp. 17-20, 2015

Authors: Kobesova, Alena | Dzvonik, Jan | Kolar, Pavel | Sardina, Angie | Andel, Ross

Article Type: Research Article

Abstract: BACKGROUND: Shoulder girdle stabilization influences hand strength but the effects of functional training remain unknown. OBJECTIVE: To determine the influence of shoulder girdle stabilization on hand muscle strength. METHODS: Handgrip strength (with hand in neutral position, supination, pronation) and tripod pinch strength were measured in 20 healthy volunteers (10 in training/control groups) weekly over six weeks. The training consisted of six specific Dynamic Neuromuscular Stabilization (DNS) exercises performed five times per week. The …exercises were designed to obtain maximum joint stability within the shoulder. RESULTS: Using mixed effects models, the training group showed significant improvement relative to the control group on all measures of hand muscle strength (p< 0.05). The gains were particularly pronounced in handgrip strength in the neutral position (dominant hand: Estimate=0.26, standard error [SE]=0.04, p< 0.001; non-dominant hand: Estimate=0.23, SE=0.03, p< 0.001). That is, the training group gained about 0.25 standard deviations over the control group per session for a total of 1.5 standard deviations (about 27 Newtons) across all sessions. CONCLUSIONS: Shoulder girdle exercises based on DNS may generate clinically significant gains in hand muscle strength. Show more

Keywords: Upper extremity, hand-held dynamometry, functional stabilization, Dynamic Neuromuscular Stabilization, rehabilitation

DOI: 10.3233/IES-140560

Citation: Isokinetics and Exercise Science, vol. 23, no. 1, pp. 21-32, 2015

Authors: Kim, Yang-Gon | Kang, Min-Hyeok | Kim, Ji-Won | An, Duk-Hyun | Oh, Jae-Seop

Article Type: Research Article

Abstract: BACKGROUND: Although strength exercises for shoulder girdle protraction (SGP) have been emphasized in subjects with scapular winging, few experimental studies have SGP strength measured this function in this cohort. OBJECTIVE: To compare SGP strength and performance of the upper quarter closed-kinetic-chain in healthy subjects and patients with scapular winging. METHODS: Twenty-six men (13 patients with scapular winging, 13 controls) exerted maximal isometric SGP force against a force-measurement device while the upper quarter Y-balance …test was conducted to examine the performance of the upper quarter closed-kinetic-chain using a Y-balance kit. RESULTS: The SGP strength in the patient group was significantly lower than that of the control group (p=0.001) while the scores on the Y-balance did not differ between the groups. The correlation between strength and motion of the upper limb during performance of upper quarter closed-kinetic-chain was relatively low (r=0.394, p=0.046). A sensitivity analysis has indicated that based on the extreme values of the patient group (the maximal individual SGP strength score) and the control group (the minimal individual strength score), 4 of the patients and 8 of the healthy participants, would have been categorized as uninvolved (false negatives) and involved (false positives), respectively. However based on the mean SGP strength score, only one patient crossed into the control subjects distribution while none of the control subject have crossed into the patients distribution. CONCLUSIONS: These findings indicate that although scapular winging may be associated with SGP weakness, particularly in cases where the isometric force is less than 130 N. However, great care has to be taken in interpretation of findings while further research should be encouraged. Show more

Keywords: Scapular alignment, SGP strength, upper quarter Y-balance test

DOI: 10.3233/IES-140561

Citation: Isokinetics and Exercise Science, vol. 23, no. 1, pp. 33-40, 2015

Authors: Steffl, Michal | Bohannon, Richard W. | Houdova, Veronika | Musalek, Martin | Prajerova, Kveta | Cesak, Petr | Petr, Miroslav | Kohlikova, Eva | Holmerova, Iva

Article Type: Research Article

Abstract: BACKGROUND: Sarcopenia is defined as a loss of muscle mass and strength as well as a reduction in physical performance with aging. This study was undertaken to examine the association between specific measures of muscle mass, muscle strength, and physical performance in older women. METHODS: Sixty-nine community-dwelling women with an average age of 66 years (range 60–79) participated in this study. Their muscle mass was described using bioelectric impedance analysis (BIA), their muscle strength was characterized …using hand-grip dynamometry (HGD) and their physical performance was denoted using gait speed. Associations between the measures were examined using Pearson correlations and factor analysis. RESULTS: The correlation between muscle mass and muscle strength was strong and significant (p< 0.001), whereas the correlation between both variables and gait speed was poor and not significant. The factor analysis showed that gait speed (loading=−0.235) was not part of the same component as muscle mass and grip strength. CONCLUSIONS: Muscle mass and muscle strength were very closely linked with one another but not with gait speed. Muscle mass and strength represent a different component of sarcopenia than physical performance, at least as represented by gait speed. Show more

Keywords: Body composition, muscle strength, physical performance, bioelectric impedance analysis, handgrip dynamometry, usual gait speed

DOI: 10.3233/IES-140562

Citation: Isokinetics and Exercise Science, vol. 23, no. 1, pp. 41-44, 2015

Authors: Borges, Viviane Santos | Domingues, João Marcos | Dias, Rosângela Corrêa | Garcia, Patrícia Azevedo | Dvir, Zeevi

Article Type: Research Article

Abstract: OBJECTIVES: To assess the strength of the flexors and extensors of the knee and hip joints in elderly and in young individuals. METHODS: A group of elderly women (N=47) and men (N=44) aged 65 and older and a group of young women (N=15) and men (N=15) aged between 20 and 30 years were tested for the isokinetic strength of the hip and knee flexors and extensors. RESULTS: A typical age-related decrease in the strength of all tested …muscles was observed but the decline in hip muscles strength, compared to those of the knee, was significantly lower, by about 10%. Moreover, women presented a significantly better strength preservation than men. The consistency of performing the repeated isokinetic efforts was higher, in some instances significantly so, in the older (range: 4.4–11%) than in the younger (3.5–6.3%) individuals but the differences do not seem to convey any clinical significance. CONCLUSION: These findings enable clinicians to set valid rehabilitation goals, particularly with respect to hip dysfunction in the elderly. Furthermore, healthy elderly individuals perform maximal isokinetic tests with substantially similar degree of gross motor control compared to that of young individuals. Show more

Keywords: Muscle strength, hip, knee

DOI: 10.3233/IES-140563

Citation: Isokinetics and Exercise Science, vol. 23, no. 1, pp. 45-51, 2015

Authors: Ribeiro, Alex S. | Schoenfeld, Brad J. | Pina, Fábio L. C. | Souza, Mariana F. | Nascimento, Matheus A. | dos Santos, Leandro | Antunes, Melissa | Cyrino, Edilson S.

Article Type: Research Article

Abstract: BACKGROUND: Studies are conflicting as to whether single-set resistance training (RT) are as effective as multi-set protocols with respect to promoting muscular adaptations. Several meta-analyses have shown that a clear dose-response relationship exists between RT volume and muscular adaptations. However, a majority of studies were not specific to older individuals, particularly women. OBJECTIVE: To determine changes in strength and body composition in elderly women following 1 vs. 3 sets of RT. METHODS: Thirty …older women participated in a 12-week supervised total body RT program. Participants were randomly assigned to perform either 1 set (G1S) or 3 sets (G3S) per session. All other RT variables were held constant. Body composition was assessed by dual X-ray absorptiometry, muscle strength was evaluated by 1RM in chest press and knee extension. RESULTS: Increases in strength were significantly (p< 0.05) greater in G3S versus G1S in both the chest press (+26.6%, versus +20.3%) and the knee extension (+23.9% versus +16.2%). No significant (p> 0.05) differences were noted in body composition components between groups. CONCLUSIONS: Findings indicate that multiple set protocols are required to optimize strength gains in older women. Changes in body composition appear to be similar irrespective of training volume during the initial stages of RT. Show more

Keywords: Strength training, fat-free mass, fat mass, volume

DOI: 10.3233/IES-140564

Citation: Isokinetics and Exercise Science, vol. 23, no. 1, pp. 53-60, 2015

Authors: Tutté, María Laura | Viladomat, Merce Avellanet | Coppin, Oliver Valero | Cervantes, Didac Haro | Muñoz, Jose Ignacio Torrero

Article Type: Research Article

Abstract: BACKGROUND: Osteoarthritis (OA) is the most prevalent joint pathology and an important cause of disability among people over 65 years of age. Following total knee replacement (TKR), which may be the only curative intervention, function is mainly affected by quadriceps weakness whose extent can accurately be assessed using isokinetic dynamometry. AIM: To evaluate the association between the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and the Hospital for Special Surgery Score (HSS) scores …and knee muscle isokinetic strength and fatigue findings in TKR patients 2–5 years postoperatively as well as assess the reproducibility and validity of the isokinetic test findings in this cohort. DESIGN: Twenty-four women who underwent TKR filled in the WOMAC and HSS questionnaires. The isokinetic test was carried out at 120 and 180°/s in concentric flexion/extension. The maximal isokinetic strength was evaluated as the peak torque (PT). Isokinetic fatigue was measured using the fatigue index and calculated based on 40 repetitions at 120°/s. The same protocol was performed 7 days apart. Test-retest reproducibility was analyzed using intraclass correlation coefficient (ICC), the standard error of measurement (SEM) and Bland Altman plots. HSS and WOMAC internal consistency was tested with Cronbach's alpha; questionnaire validity and correlations were obtained using Spearman's rho. RESULTS: The HSS Function sub-score was significantly correlated with quadriceps PT but not with fatigue isokinetic scores. Excellent reproducibility was indicated for all outcome measures, with the exception of the HSS Knee subscore and the fatigue index. CONCLUSIONS: Isokinetic dynamometry of the quadriceps can provide objective and useful information regarding the functional status of patients following TKR due to OA of the knee. Show more

Keywords: Isokinetic testing, knee prosthesis, strength, reproducibility

DOI: 10.3233/IES-140565

Citation: Isokinetics and Exercise Science, vol. 23, no. 1, pp. 61-67, 2015