bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electromagnetically braked versus mechanically braked cycle ergometers: Effects of aerobic power and total physical workloads
Authors: Ozkol Mehmet Zeki 
Published: October 2018

OBJECTIVE: To determine the differences in physiological performance at constant submaximal load and aerobic power levels of electromagnetically and mechanically braked cycle ergometers. METHOD: Nineteen trained male athletes who specialize in cycling and triathlons participate in this study (age, 20.21 ± 3.50 years; body mass, 73.36 ± 13.19 kg; height, 178.73 ± 8.54 cm). A randomized cross-over study design was used to compare a mechanically braked Monark cycle ergometer (MCE) and an electromagnetically braked Lode Excalibur cycle ergometer (ECE). After the VO $_{2max}$ test, total physical work capacity and work efficiency(GE) were analysed during 60% of VO $_{2max}$ constant loading submaximal tests with MCE and ECE. A paired sample t-test was used to compare VO $_{2max}$ and constant loading submaximal test data of the ergometers. RESULTS: Applying the ECE system resulted in a significantly higher VO $_{2max}$ value (9.3%; p=0.004), similar respiratory exchange ratio value (1.8% lower; p=0.290), similar power output at exhaustion point (1% higher; p=0.620), significantly higher total energy expenditure at exhaustion point and mean cadence(Cad $_{mean}$ ) value (12%; p=0.025, 9.6%; p=0.000) respectively. In the constant loading submaximal tests, however, significant differences were found in mean power output (p=0.013), Cad $_{mean}$ (p=0.000), and GE (p=0.000) values. CONCLUSION: Since the ECE system was associated with a higher VO $_{2max}$ and allowed test performance at the expected VO $_{2}$ consumption at constant submaximal loads, we recommend using the ECE for determination of aerobic power and total physical workloads.
Hip muscles strength and activation in older fallers and non-fallers
Authors: Morcelli Mary Hellen , Crozara Luciano Fernandes , Rossi Denise Martineli , LaRoche Dain Patrick , Ribeiro Marques Nise , Hallal Camilla Zamfolini , Castro Alex , Cardozo Adalgiso Coscrato , Gonçalves Mauro , Navega Marcelo Tavella 
Published: October 2018

BACKGROUND: Hip muscles dysfunction may challenge postural control mechanisms and compromise the individual in imbalance situations. OBJECTIVE: To compare hip muscles strength, power and activation between older female fallers and non-fallers. METHODS: Forty-four older adult women(60–85 yr) were divided into two groups based on having falling or not in the period of one year before evaluation, fallers (n=20) and non-fallers (n=24). Isokinetic strength and power were assessed during hip flexion, extension, abduction and adduction movements, while EMG signals were recorded from the internal oblique (IO), rectus femoris (RF), multifidus (MU), gluteus maximum(GM), and biceps femoris (BF). RESULTS: Fallers had significantly lower extension (p=0.033), abduction (p=0.001) and adduction (p=0.002) strength as well as significantly lower power in hip flexion (p=0.028), extension (p=0.005) and abduction (p=0.002) compared to non-fallers. Non-fallers had 27.4% greater activation of RF (p=0.005) during hip flexion and 37.9% higher coactivation of IO/MU during hip abduction (p=0.003). Significant linear regression was found between hip extension strength and GM and BF activation in both groups. CONCLUSION: Hip muscles strength and activation may increase the risk of falling in older women.
Hamstring muscle strength before and after anterior cruciate ligament reconstruction: A systematic review
Authors: Moloney Colum , O'Sullivan Kieran , O'Farrell Dermot , Louw Quinette , Clifford Amanda M. 
Published: October 2018

BACKGROUND: The effect of hamstring tendon grafting during anterior cruciate ligament reconstruction (ACLR) on residual hamstring muscle strength remains unclear. OBJECTIVES: To identify if hamstring muscle strength deficits exist after ACLR using the ipsilateral semitendinosus and gracilis tendons (STG) in absolute and relative terms, and ascertain if pre-operative strength influences post-operative strength outcomes. METHODS: A search was performed using five databases; MEDLINE, SPORTSdiscus, Cinahl, AMED and Cochrane. Original articles that reported both absolute and relative hamstring muscle strength on isokinetic testing after ACLR with STG grafts were evaluated, selected and critically appraised. RESULTS: Eleven studies that met the inclusion criteria were included in the review. Hamstring peak torque (PT) deficits in the reconstructed leg compared to the contralateral side ranged from 10–19% and 6.4–12.6% at six and 12∼months, respectively. Minimal deficits were reported at five to six year follow up. For absolute strength values the mean PT identified in absolute terms was low at 96 Nm at 60°/s (Range 77–121.8 Nm) with just one study normalising PT to body weight (PTBW). Only three of the included studies reported both pre- and post-operative results with two studies identifying similar reductions in PT of 8.6–9% in the operated limb from pre-operative to six months. CONCLUSION: Deficits in hamstring strength were found to exist up to one year post-operatively but appear to resolve by five to six years. It is recommended that future studies report PTBW to allow for better interpretation of results to allow for comparisons against normative data. More research is needed to examine the influence of pre-operative hamstring muscle strength on post-operative results.
Fat-free mass and bone mineral content positively affect peak torque production in Brazilian soccer players
Authors: Portella Daniel Leite , Cossio-Bolaños Marco Antonio , Hespanhol Jefferson Eduardo , de Arruda Miguel 
Published: October 2018

BACKGROUND: Few studies thus far have investigated the relationship between body composition (in particular, bone components) and isokinetic strength performance. OBJECTIVE: To determine the relationship between bone mineral content (BMC), bone mineral density (BMD), and fat-free mass (FFM) with isokinetic strength performance variables in professional soccer players. METHODS: We recruited 20 elite male soccer players from the Brazilian league's first division teams. Participants underwent a concentric isokinetic evaluation of knee flexor and extensor muscles. Dual-energy X-ray absorptiometry (DXA) was used to determine body composition. The relationships between variables were analyzed using Pearson's product-moment correlation coefficient. RESULTS: Body composition variables were correlated with the strength output of knee flexor and extensor muscles in both lower limbs. FFM and BMC explained at least 50% of the variation in peak knee flexion and extension torque while BMD did not have the same effect. CONCLUSIONS: The relationships reported in this study indicate that the use of isokinetics and DXA in soccer players should be further investigated both for measuring athletic performance and for relevant clinical assessment.
The association between conventional and dynamic control knee strength ratios in elite soccer players
Authors: Ruas Cassio V. , Pinto Matheus D. , Brown Lee E. , Minozzo Felipe , Mil-Homens Pedro , Pinto Ronei S. 
Published: October 2018

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.
Reliability of normalized surface electromyographic signals of maximal upper-body isokinetic strength
Authors: Rocha-Júnior Valdinar A. , Bottaro Martim , Pereira Maria C. , Ferreira-Júnior João B. , Carmo Jake , Brown Lee E. , Nascimento Francisco A.O. 
Published: October 2018

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.
Effects of shoulder girdle dynamic stabilization exercise on hand muscle strength
Authors: Kobesova Alena , Dzvonik Jan , Kolar Pavel , Sardina Angie , Andel Ross 
Published: October 2018

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.
Resistance training in older women: Comparison of single vs. multiple sets on muscle strength and body composition
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. 
Published: October 2018

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.
Reproducibility of isokinetic trunk muscle torque evaluation in postpartum women
Authors: Potter Helen M. , Strauss Geoffrey R. 
Published: October 2018

Isokinetic trunk muscle strength of 36 postpartum women was evaluated using the Kin-Com dynamometer at 24 and 25 weeks following vaginal delivery of a healthy infant. Test-retest reproducibility of a standardised isokinetic testing protocol was evaluated in concentric and eccentric muscle actions through a 50° range of motion at velocities of 20 deg/s and 40 deg/s for the trunk flexors and extensors. Moderate agreement was found for inter-test reproducibility (ICCs from 0.67 to 0.85; CVs from 8.8% to 15.9%). Intratest reproducibility was high (ICCs from 0.90 to 0.95). The ratio of trunk extensor to flexor strength was similar in both concentric and eccentric action at both velocities (p>0.05). The ratio of strength at the two velocities was similar for both muscle groups in both actions (p>0.05). Eccentric strength was significantly higher than concentric strength. Eccentric strength did not vary with velocity while concentric strength displayed an inverse relationship with velocity (p<0.05).
Age related changes in muscle strength and fatigue
Authors: Melzer I. , Benjuya N. , Kaplanski J. 
Published: October 2018

The purpose of the current study was to establish that the measurements taken during dynamic contractions could provide insight into differences/similarities that evolve between muscle mechanics and it's neuromuscular (electrical) source as one aging. The present study assesses the differences in strength that is resistance to fatigue (RTF) of the knee extensors (vastus lateralis (VL) and vastus medialis(VM)) as a function of age and gender. Eighty subjects (45 males and 35 females) with a-symptomatic knees were tested; Males: Group A, 20--29 years old ( $N=20$ ); Group B, 30--39 years old ( $N=8$ ); Group C, 40--49 years old( $N=9$ ); Group D, 50--60 years old ( $N=8$ ) and the Females: Group E, 20--39 years old ( $N=25$ ); Group F, 40--60 years old ( $N=10$ ). All subjects were tested for their dominant knee extensor strength by performing a maximal voluntary isometric contraction (MVIC) and fatiguing bouts at four isokinetic velocities of 300 $^{\circ}$ /sec, 180 $^{\circ}$ /sec, 60 $^{\circ}$ /sec, 30 $^{\circ}$ /sec. The muscular fatigue was assessed by comparing the median frequency (MF) of the surface EMG (SEMG) activity of VL and VM during the 2nd contraction and the 20th (last) contraction of the bouts. The results showed distinct differences between groups A, B and C, D similarly between group E and F in muscle strength, when performing isokinetic concentric contraction. There was no age and gender difference in isokinetic fatigue ratio (IFR) and in electromyographic measurements in MF of VM and VL. The decrease in knee extensor strength occurred in the 4th decade for the males and in the 3rd for the females. These results of this study provide quantitative evaluation of knee strength of sedentary adults at various ages. The knowledge of the critical age group allow us to construct a fast, reliable and valid test in assessing the condition of main anti-gravity muscles and alert the person before any stability deficiencies may crop out. The isokinetic findings were in line with the SEMG findings that is the phasic (strength) component of knee extensors decreased with age while there is no significant difference in tonic(endurance) component up to 60 years old. It is anticipated that the proposed protocol as administered may be useful in occupational settings.
The effect of submaximal eccentric isokinetic training on strength and cross sectional area of the human achilles tendon
Authors: Mouraux D. , Stallenberg B. , Dugailly P.-M. , Brassinne E. 
Published: October 2018

This study was designed to investigate the effects of six weeks submaximal eccentric training on concentric and eccentric isokinetic peak torque and cross sectional area (CSA) (muscle and tendon) of calf muscle. Six men and four women volunteered as subjects for this study. Peak torque values for plantar flexion were determined at 30 $^{\circ}$ /s, 60 $^{\circ}$ /s and 90 $^{\circ}$ /s (concentric and eccentric) using a Cybex $^{\textregistered}$ Norm before the training, 3 weeks after the beginning and at the end of the sixth week. Following training, peak torque increased in the concentric and eccentric modes in both the trained ( $p<0.001$ ) and untrained( $p<0.01$ ) side. No significant change in CSA was noted. The results of this study indicate that after 6 weeks of submaximal eccentric training the strength gained was not completely specific to the contraction type used in training. Transfer of training took place. Neither muscle nor tendon hypertrophy was observed, suggesting the involvement of neural adaptation.
The quantification of reciprocal shoulder strength relation in various working modes at different movement velocities
Authors: Mayer F. , Baur H. , Hirschmüller A. , Heitkamp H.C. , Horstmann T. , Dickhuth H.H. 
Published: October 2018

Muscular balance appears to be decisive for dynamic shoulder stability, since passive stabilizers do not take effect until the end of range of motion in order to not limit joint mobility. Changes in strength relationships are frequently viewed as one of the causes of shoulder pathologies. However, objective quantification of reciprocal strength relationships is difficult. In particular, the influence of movement velocity on the strength ratios during the test has not been clarified. Determination of the strength relationships of reciprocal muscle groups (quotient of maximum torques) was performed on a total of 166 untrained men (M) and 83 untrained women (F) for extension/flexion, abduction/adduction and rotation movements of the shoulder. Moreover, differentiation was made by various working modes and movement velocities (isometric at various angle positions, concentric at 60°/s and 180°/s, eccentric at 60°/s and 120°/s). The results show a decreasing order of strength relationships: Abduction/Adduction > Flexion/Extension > External/Internal rotation. In spite of marked differences in absolute values, no differences were noted among the contraction modes (isometric, concentric, eccentric) or movement velocities(p>0.05). A slightly reduced ratio of rotational movements in concentric mode was the only conspicuous finding. Unlike isokinetically-determined absolute torque values, a relevant velocity-dependence must not be expected with respect to reciprocal strength relationships of the shoulder muscles. A different (neuro)-muscular structure of the muscle groups involved with a corresponding effect on the strength-performance ratio thus does not appear to be present or cannot be detected in isokinetic tests. However, further research is warranted regarding the effect of the various associated factors (e.g. stabilization) on the reliability and validity of isokinetic findings relating to this specific joint-muscles system.
The effect of age on isokinetic concentric and eccentric moment of knee extensors
Authors: Bassa E. , Kotzamanidis C. , Patikas D. , Paraschos I. 
Published: October 2018

The aim of the present study was to examine the concentric and eccentric isokinetic moment of knee extensors in 108 boys aged 6 to 12 years and in 15 young adults. Participants performed isokinetic concentric and eccentric knee extensions at different angular velocities, 45°, 90° and 180°·s $^{-1}$ . The Ancova designs, using lean mass as covariate, revealed a significant age effect. Post hoc Scheffe test revealed higher moment scores for adults compared to children. Statistical differences between children were observed every two years. Eccentric moments were higher than concentric moments at corresponding velocities. Concentric moments decreased with increasing velocity whereas eccentric moments did not change significantly. Boys were found to achieve almost 40% concentric and eccentric moment of young adults at the age of 12 years. The higher annual increase of both concentric and eccentric moment was observed at 7 years of age. The present data indicate a gradual and concurrent increase of isokinetic concentric and eccentric moment with age from 6 to 12 years of age suggesting probably a concurrent maturation of contractile and elastic components of the muscle during childhood.
Isokinetic evaluation of hip strength muscle groups in unilateral lower limb amputees
Authors: Croisier J.L. , Maertens de Noordhout B. , Maquet D. , Camus G. , Hac S. , Feron F. , De Lamotte O. , Crielaard J.M. 
Published: October 2018

The objectives of the study were to measure the isokinetic strength of the hip flexor-extensor and adductor-abductor muscle groups in unilateral lower limb amputees and to evaluate abnormalities in order to improve the usual rehabilitation programs. Thirty-three patients with unilateral lower limb amputation were included in this study; they served as their own controls, the amputated side being compared to the intact side. Using an isokinetic device, the relative peak torques (N.m by body weight), bilateral asymmetries and agonist/antagonist torque ratios were calculated for the hip flexor, extensor, adductor and abductor muscle groups. A significant reduction of mean concentric relative peak torque measured on the amputated limbs was generally observed when compared to the intact contralateral limb (p < 0.05). The mean percentage of relative peak torque decrease was greater for the extensors than for the flexors (33 ± 20% angular velocity), and for the abductors than for the adductors (23 ± 22% Furthermore, the flexor/extensor torque ratio was significantly increased for the amputated limb (for instance, 1.25 ± 0.33> versus 1.09 ± 0.25 for the intact limb at 30°/s). The reduction of the abductor/adductor ratio of the operated limb reached the level of statistical significance at 60°/s only(1.25 ± 0.46 versus 1.07 ± 0.36 for the intact limb). In conclusion, isokinetic testing revealed a significant reduction of the hip stabilizing muscle strength as a consequence of lower limb amputation. The more marked decrease of the strength of the abductor and extensor muscle groups, resulting in imbalances of the agonist/antagonist strength ratios should be taken into account to adapt the conventional rehabilitation programs.