bluuebunny/crossref_metadata_2025 huggingface dataset:
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.
Comparison of Peak Torque and Hamstring/Quadriceps Femoris Ratios During High-Velocity Isokinetic Exercise in Sprinters, Cross-Country Runners, and Normal Males
Authors: Kuhn Sarah , Gallagher Andrea , Malone Terry
Published: October 2018

The purpose of this study was to compare the overall peak torque per kilogram body weight (peak torque/kg) and hamstring to quadriceps femoris (H/Q) peak torque ratios between 13 male intercollegiate sprint athletes, 10 male intercollegiate cross-country runners, and 11 normal males at angular velocities of 271, 375, 472 and 583 deg/sec. A modified Cybex II isokinetic dynamometer was used for all data collection. The dominant leg of each subject was tested at all four test velocities and the non-gravity-corrected peak torque/kg values of the hamstrings and quadriceps femoris as well as the H/Q peak torque ratios were analyzed. The results were: (1) Sprinters produced a significantly greater (p < 0.05) values for both hamstrings and quadriceps femoris than normals at 271, 472, and 583 deg/sec and significantly greater quadriceps femoris peak torque/kg than cross-country runners at 583 deg/sec. (2) Cross-country runners produced significantly greater peak torque/kg hamstring values than normals at 472 deg/sec. (3) No significant differences were found for H/Q peak torque ratios between groups at each speed or between speeds for each group. (4) The absolute differences between peak torque/kg values of the hamstrings and the quadriceps femoris decreased with increasing velocity for all groups. (5) Cross-country runners' hamstring peak torque/kg values exceeded the quadriceps peak torque/kg values at 583 deg/sec.
Functional Subluxation of the Glenohumeral Joint in a College Pitcher
Authors: Dickoff-Hoffman Steven
Published: October 2018

A 21-year-old male college baseball pitcher with a diagnosis of “impingement syndrome” was seen in sports physical therapy for a rehabilitation program. Physical evaluation revealed restricted internal rotation flexibility, diminished external rotator and scapular stabilizer strength, and a mechanical flaw in his throwing technique. He was placed on an isokinetic strengthening regimen for his rotator cuff, a flexibility routine to address internal rotator tightness, and a progressive throwing program. Ten weeks following this program, the patient was asymptomatic, exhibited “normal” isokinetic and flexibility parameters, and was able to return to competition without pain or restriction in function.
A Comparison of the LIDO Sliding Cuff and the Tibial Control System in Isokinetic Strength Parameters
Authors: Brown Lee E. , Whitehurst Michael , Bryant Jennifer R.
Published: October 2018

The purpose of this study was to compare the tibial control system (TCS) and sliding cuff (SC) lever arms in the strength parameters peak torque (PT), average work (AW), average power (AP), joint angle at peak torque (JA), and fatigue index (FI). Fifteen healthy subjects, with no history of knee pathology, performed three knee extension/flexion repetitions using the right leg at a velocity spectrum of 60, 180, 240, and 20 repetitions at 300 deg/sec for each lever arm. TCS and SC were randomly presented with 24 hours between conditions. Significance was set at p < 0.05. Paired t tests showed that the SC produced significantly greater PT, AW, and AP than the TCS during extension across velocities. Also, SC JA occurred significantly later in the range of motion across velocities, whereas FI was significantly greater for the SC than the TCS at 300 deg/sec. Paired t tests for flexion data indicated that the TCS produced significantly greater PT than the SC across velocities and greater AP at 60 deg/sec. The SC condition resulted in significantly greater AW and AP at 300 deg/sec only. The SC and TCS conditions did not differ for JA and FI across velocities. It was concluded that choice of lever arm significantly influenced the strength parameters examined in this study.
Gender Differences in the Isokinetic Torque-Velocity Relationship
Authors: Wagner Loree L. , Housh Terry J. , Weir Joseph P. , Johnson Glen O.
Published: October 2018

The purpose of this investigation was to determine if there are gender differences in the isokinetic torque-velocity curves constructed from peak torque (PT) and constant joint angle (i.e., angle-specific torque) (CJA) torque values for leg flexion and extension. Ten female and ten male university students performed leg extension and flexion movements at velocities of 0, 48, 96, 144, 192, 240, and 288 deg/sec (zero, 0.84, 1.68, 2.51, 3.35, 4.19, and 5.03 rad/sec) on a Cybex II isokinetic dynamometer. The results indicated that the plateau in CJA torque output for the men extended from 0 to 192 deg/sec (0–3.35 rad/sec) for leg extension and 0 to 96 deg/sec (0–1.68 rad/sec) for leg flexion. For the women, the torque plateau extended from 0 to 144 deg/sec (0–2.51 rad/sec) for leg extension and 0 to 48 deg/sec (0–0.84 rad/sec) for leg flexion. For both CJA and PT output, the men showed a smaller percent decline (relative to maximal values) than the women with increasing velocities. These findings support the presence of gender differences in the PT and CJA torque-velocity relationships for leg extension and flexion.
Elbow Flexion and Extension Force During Testing in Different Positions
Authors: Capuano-Pucci Donna , Clifford Jeff A. , Gillan Matthew D. , Pleva David J. , Seiler Jason S.
Published: October 2018

The purpose of this study was to determine the effect of different body positions on the force generated by elbow flexor and extensor muscles. The Nicholas Manual Muscle Tester, a hand-held dynamometer, was used to measure the force generated by the muscles. A random sample of 28 healthy subjects was tested by a single examiner. Each muscle group was tested with gravity eliminated and with the subjects sitting and supine. The dynamometer was positioned on the extremity and a break test was performed. The data were analyzed using the two-way analysis of variance for repeated measures. A significant difference in the force generated by the muscles was noted between positions (p < 0.05) for both elbow flexors and extensors. Alterations in body position appear to influence the amount of force generated by the elbow flexor and extensor muscles.
Juxtaarticular Muscle Function in Relation to Joint Distension
Authors: Geborek Pierre
Published: October 2018

The relation between joint distension and juxtaarticular muscle function is reviewed with focus on human studies. The neurophysiological background and the methods used in humans are examined. The importance of treating the underlying cause for joint distention is stressed. especially regarding chronic compared with acute exudates. Aspiration of acute exudates is recommended in some cases to minimize juxtaarticular muscle wasting. Possible function studies are outlined.
A Comparison of Two Proprioceptive Neuromuscular Facilitation Techniques for Improving Range of Motion and Muscular Strength
Authors: Lustig S.A. , Ball T.E. , Looney M.
Published: October 2018

The purpose of this study was to examine the effects of two proprioceptive neuromuscular facilitation (PNF) stretching procedures on flexibility and muscular strength. Subjects were 41 females enrolled in dance fitness classes at a large state university. One class was designated as the control, whereas the other class subjects were randomly assigned to a slow reversal. (SR) PNF group (n = 12) or a contract-relax (CR) PNF group (n = 10). The treatment groups participated in a supervised PNF program three times per week for 7 weeks. All subjects were pre- and posttested for flexibility and strength of the hip extensors. Adjusted posttest mean flexibility scores did not significantly differ between groups (F(2.37) = 2.12, P > 0.05). However, the SR and CR groups showed 6.2% and 6.8% mean increases in hip flexibility, respectively, whereas the control group showed only a 0.7% mean increase. Adjusted posttest scores of strength were significantly different between groups (F(2.37) = 7.35, P < 0.05). Tukey's post hoc test showed significant differences between the control and two treatments (P < 0.05), but no significant difference between the two treatment groups (P > 0.05). The results of this study suggest that SR and CR PNF stretching procedures may be effective for increasing flexibility and developing muscular strength for some groups. Such information is of practical importance to coaches, athletic trainers, and exercise specialists interested in maintaining and increasing strength through the use of PNF stretching procedures.
A Comparison of Dynamic Muscular Endurance Among Inactive Men and Women: A Cross-Sectional Study
Authors: Kulling Frank A. , Beisiegel William P. , Jacobson Bert H. , Edwards Steven W.
Published: October 2018

The purpose of this study was to investigate, using the YMCA Bench Press test, the absolute, dynamic, upper body muscular endurance (ME) of inactive men and women 20–49 years of age. The subjects were 215 men and 151 women. Data were factored by gender, and decade of life and compared using a two-way analysis of variance with 0.05 chosen as the level of significance. The Tukey-Kramer test was used to locate significant post hoc differences. Results indicated women performed more repetitions than men (P = 0.018) and fifth decade participants performed fewer repetitions than their third and fourth decade counterparts (P = 0.020). There was no significant (P > 0.05) age by gender interaction concerning bench press performance. We conclude that inactive, fifth decade men and women are likely to possess reduced absolute, dynamic upper body ME when compared with their younger counterparts, and that inactive adult women are likely to perform more repetitions in the YMCA bench press test than inactive adult men.
The Mechanical and Physiological Performance Reliability of Selected Isokinetic Dynamometers
Authors: Timm Kent E. , Gennrich Peter , Burns Ray , Fyke Dennis
Published: October 2018

We report 14 separate studies of the mechanical and/or physiological performance reliabilities of selected isokinetic dynamometers, including the Biodex, Cybex 340, Cybex Liftask, Cybex TORSO, Cybex TEF, and Merac systems. A total of 171 volunteer subjects (85 females, 86 males; age range 16–34 years) were randomly assigned to a dynamometer for physiological reliability testing. Testing consisted of five maximal performance efforts across a velocity spectrum. Each session was preceded by an isokinetic and cardiovascular warm-up, through a controlled range of knee, spine, or lifting motion in a test/retest design separated by 48 hours. Mechanical reliability testing consisted of five repetitions of dropping a certified load through a controlled motion arc across a velocity spectrum, also under the test/retest paradigm. Intraclass correlation statistical procedures showed significant levels of mechanical and physiological test/retest reliability for each of the tested dynamometer systems. Within the limitations of the study, the selected isokinetic devices demonstrated reliability for performance measurement during concentric isokinetic, eccentric isokinetic, or concentric isotonic functions, depending on the specific device.
Reliability of the LIDO Active Isokinetic Dynamometer Concentric Mode
Authors: Brown Lee E. , Whitehurst Michael , Bryant Jennifer R.
Published: October 2018

The purpose of this study was to assess the test-retest concentric reliability of the LIDO Active isokinetic dynamometer. Twenty subjects performed knee extension and flexion on two separate days, 48 hours apart. Peak torque (PT), average work (AW), average power (AP) and joint angle at peak torque (JA) were measured at 60, 180, 300 and 400 degrees per second (deg/sec). Pearson product moment (r) correlations between day 1 and day 2 for PT, AW, and AP ranged from 0.90 to 0.99. The JA r values ranged from 0.09 to 0.92. Extension paired t-tests revealed that mean values for PT, AW, AP and JA on day 1 were not significantly (p < 0.05) different from mean values on day 2, with the exception of AW at 300 deg/sec. Flexion t tests indicated that PT values were not different. Average work was significant at all velocities except 300 deg/sec, while AP and JA were significant at 180 and 60 deg/sec, respectively. It was concluded that the LIDO Active isokinetic dynamometer is a reliable instrument to assess concentric isokinetic strength.
The Effects of Electrical Stimulation and Electromyographic Biofeedback on Muscle Performance Output with Training of the Quadriceps Femoris Muscle
Authors: Convery Aileen , Racer Billy , Rohland Rick , Shannon Jeanette , Sorg Joe
Published: October 2018

The purpose of this study was to examine muscle performance output as effected by electrical stimulation with and without eledromyographic (EMG) biofeedback in conjunction with quadriceps femoris muscle (QFM) strengthening exercises. Six males and six females aged from 20 to 36 participated in this study. Subjects were assigned to one of three independent groups. One group (n = 4) performed maximal volitional isometric contractions (MVICs) of the QFM and served as the control; the second group (n = 4) underwent strength training augmentation concurrent with electrical stimulation; the third group (n = 4) received EMG biofeedback-triggered electrical stimulation (BTES), i.e., electrical stimulation based on EMG biofeedback from volitional isometric contractions. Each group underwent pretesting and posttesting to record MVICs. The groups trained 3 days a week for 6 weeks. All groups had an increase in peak torque production over the 6-week training period, with the EMG-BTES group showing the greatest increase from pretest to posttest. Results of this study give preliminary evidence of the usefulness of electrical stimulation, especially when triggered by an EMG biofeedback signal, in strength training.
The test-retest reliability of a one legged hop for distance in young adults with and without ACL reconstruction
Authors: Paterno Mark V. , Greenberger Hilary B.
Published: October 2018

This investigation was designed to determine the test-retest reliability of a functional one legged hop test for distance in individuals with and without anterior cruciate ligament (ACL) reconstruction. Twenty subjects (X = 20.85 years) with no prior history of lower extremity injury, and 13 subjects (X = 22.40 years) with ACL reconstruction participated in this study. Testing occurred on two separate days with at least 24 h between testing sessions. The subjects executed a protocol consisting of a 5-min warm-up on a stationary bike, followed by three separate trial hops. This was followed by three separate hops which were measured and recorded. The distance travelled for each hop was measured using a standard measuring tape. The same protocol was then repeated on the contralateral limb. The leg tested first was randomized with each subject. The subjects were then asked to return on the second day, wearing the same pair of athletic shoes, and repeat the identical protocol. The mean of the three hops were used in data analysis. Paired t-tests revealed no significant difference between the dominant and non-dominant legs on either pre-test or post-test in subjects with healthy knees. A significant difference was found when comparing involved to uninvolved limb on both the pre-test and post-test in patients with ACL reconstruction. There was no significant difference found from pre-test to post-test on either the dominant or non-dominant legs in healthy subjects or from the involved to uninvolved in patients with ACL reconstruction. Interclass correlation coefficients (ICC) revealed values of 0.92 and 0.96 for dominant and non-dominant legs, respectively. For individuals with ACL reconstruction, ICC values were 0.89 for both the involved and uninvolved limb. The results of this study suggest that the one legged hop test for distance is a reliable test for both young adults with healthy knees and those who have had ACL reconstruction. This test, along with others, may aid clinicians in determining whether patients are ready to return to prior level of activity.
The effect of previous contraction condition on subsequent eccentric power production in elbow flexor muscle
Authors: Kroll Penny G. , Nelson Arthur J. , Nordin Margareta
Published: October 2018

This study examined the effect of previous contraction condition on subsequent eccentric power production in the elbow flexor muscles in 20 healthy volunteers (10 males, 10 females). Power production was determined during constant velocity eccentric loading at 60°/s when preceded by: condition 1 passive elbow flexion; condition 2 maximal concentric contraction of the elbow flexor muscles; or condition 3 maximal isometric contraction of the elbow flexors. Comparison of eccentric power production under the different conditions was conducted using a repeated measures ANOVA. Results indicated that a continuum exists between conditions such that eccentric power production when preceded by condition 1 is < power production when preceded by condition 2, is < power production when preceded by condition 3. Implications are that contraction condition previous to eccentric loading allows various levels of tension transfer in the series elastic and the contractile components producing different levels of torque during the ensuing eccentric loading of the muscle. Techniques utilizing combinations of movement to enhancing muscle contraction should be examined critically with regard to order of movement and contraction conditions.
Muscular strength relationship between normal grade manual muscle testing and isokinetic measurement of the shoulder internal and external rotators
Authors: Ellenbecker Todd S.
Published: October 2018

The measurement of muscular strength of the shoulder internal and external rotators is an integral part of the comprehensive evaluation and treatment of the shoulder joint. The purpose of this study was to compare normal grade (5/5) manual muscle strength with isokinetic testing of the shoulder internal and external rotators. One hundred and fourteen consecutive subjects were tested isokinetically in the supine position with 90° of glenohumeral joint abduction on a Cybex 3S0 dynamometer. Prior to isokinetic testing each patient was tested by two physical therapists using manual muscle testing (MMT) with the shoulder abducted 90° for internal OR) and external (ER) rotation. All subjects were rated as normal (5/5) grade for both IR and ER by both therapists to be included in this investigation. A two factor analysis of variance was used to test for differences between extremities. Results of this study showed significant (P < 0.01) differences between extremities in isokinetic peak torque and single repetition work scores. Differences between extremities ranged from 11 to 28% among a sample with normal grade (MMT). The results of this study identify objective, isokinetically measured discrepancies in muscular strength in subjects rated as ‘normal’ in shoulder internal and external rotation strength. This study demonstrates the efficacy of isokinetic testing of the shoulder internal and external rotators in clinical rehabilitation and evaluation of the glenohumeral joint.
Isokinetic trunk flexors and extensors performance with and without gravity correction
Authors: Vanhée J.L. , Voisin Ph. , Vezirian Th. , Vanvelcenaher J.
Published: October 2018

We study the influence of the calculation of the trunk gravity correction, in standing position, on the isokinetic trunk flexors and extensors performance of a healthy population. Thirty men and 30 women are subjected to two tests, one with gravity correction, the other without, at angular speeds of 30°/s and 120°/s. In all cases, the results with gravity correction show: a significant decrease of Peak Torque (PT) and Power (P) recorded on the trunk flexors and a significant increase of Peak Torque and Power recorded on the trunk extensors. Thus, the flexors/extensors ratios (50%) of both parameters are quite different from the ratios usually referred to in the literature (70%).
Effect of ankle position on knee flexor and extensor torque
Authors: Miller John P. , Catlaw Kerriann , Angelopoulas Charles
Published: October 2018

The purpose of this study was to examine the effect of ankle position on knee flexor and extensor torque at 60 and 180°/s. Twelve female athletes had their dominant and non-dominant limb tested on a Cybex II + dynamometer (Cybex, Ronkonkoma, NY) under two conditions: with the ankle plantarflexed and dorsiflexed. Paired t-tests showed no statistical differences in knee extensor torque. Significant differences were noted in knee flexor torque at both 60 (P < 0.05) and 180 (P < 0.01)°/s with the greatest torque being seen with the ankle in the dorsiflexed position. These results suggest that ankle position affects knee flexor torque during open chain isokinetic movements.
Relationship between drop vertical jump heights and isokinetic measures utilizing the stretch-shortening cycle
Authors: DeStaso Joel , Kaminski Thomas W. , Perrin David H.
Published: October 2018

The purpose of this study was to determine how isokinetic eccentric and concentric peak torque/body weight ratios and time to peak torque values relate to drop vertical jump heights in 30 healthy subjects (12 men and 18 women, age =22.7±2.2 yr, ht =169.6±8.9 em, wt =67.2±11.9 kg). Drop vertical jumps were performed from a box 50 cm high. Subjects were tested isokinetically on each leg for the motions of knee extension and ankle plantar flexion. Eccentric and concentric peak torque (PT)/body weight ratios along with time (s) to eccentric and concentric peak torque were extracted from the Kin Com II computer. A stepwise multiple regression analysis was conducted to determine the relationship between the eight predictor variables and drop vertical jump height. Knee extension concentric PT/body weight ratio was the most significant predictor of drop vertical jump height, accounting for 23% of the variance. This finding suggests that the stretch-shortening cycle can be simulated using isokinetic strength measurements and that drop vertical jump height can be attributed in part to concentric knee extension strength.
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).
Elbow and hand muscle strength are not affected by head--neck position
Authors: Rex Wong Y.C. , Cameron Denise , Bohannon Richard W.
Published: October 2018

This investigation was conducted to examine the influence of head and neck (H--N) position in the transverse plane on the static muscle strength of elbow flexion and extension and hand grip. Subjects were 36 apparently healthy young females (23-36 years). Strength was measured instrumentally. The strength of each action was measured twice on both sides on each of two days about one week apart. Separate analysis of variance procedures applied to each action of each side (eg left hand grip) demonstrated no significant effect of H--N position, trial, or day. Intraclass correlation coefficients (ICCs) showed intertrial and interday reliability to be high (ICCs = 0.96 - 0.99. This study provides no evidence that H-N position needs to be considered when testing the upper extremity strength of neurologically intact women. The study confirms the reliability of both hand-held and hand grip dynamometry.
Reliability of measurement of knee extensor and flexor muscle peak torque on the KinCom isokinetic dynamometer in individuals with rheumatoid arthritis
Authors: McMeeken Joan M. , Story Ian H. , Smith Jenni , Ken Peter
Published: October 2018

Reliability of measurement of maximum isokinetic muscle performance in subjects with rheumatoid arthritis has not been reported for the KinCom dynamometer. The aim in this study was to estimate intra and inter-session reliability in knee extensor and flexor muscles. Concentric peak torque (Nm) of knee extension and flexion at 60o.s-1 and 120o.s-1 was measured in 18 subjects(49.7 +/- 5.3 (29-76) years) with rheumatoid arthritis using a standardised protocol. Intra-session reliability (ICC 3,1) assessed in six subjects was found to be high in extensor (0.99) and flexor muscles (0.99). Comparison between left and right knees showed no statistically significant differences. Inter-session reliability (ICC 2,3) assessed over a six-week interval was also high for extensors (60o.s-1 = 0.97, 120o.s-1 = 0.97) and flexors (60o.s-1= 0.94, 120o.s-1= 0.97). These findings indicate that when using a single rater, inter and intra-session reliability of knee muscle peak isokinetic concentric torque measurement are acceptable. The time interval between test sessions of six weeks reflects the clinical environment. Therefore this protocol provides a useful test for evaluation of therapeutic interventions directed at the knee.
Effect of movement velocity on the median frequency of the electromyographic activity of the quadriceps and hamstrings during isokinetic testing
Authors: Hutchins Ronald , Miller John P. , Croce Ronald
Published: October 2018

The purpose of this study was two-fold: 1) to examine the median frequency of the electromyographic activity (mfEMG) of the quadriceps and hamstrings during isokinetic movements at 60, 180 and 300o.s-1 and 2) to examine the changes in the mfEMG with fatigue at 300o.s-1. Fourteen female athletes had their dominant limb tested on a Cybex II+ isokinetic dynamometer (Cybex, Ronkonkoma, NY). The mfEMG of the quadriceps and hamstring muscle groups was determined by placing bipolar surface electrodes on the vastus lateralis, vastus medialis, biceps femoris, and medial hamstrings. Repeated measures ANOVA indicated no effect of movement velocity on the mfEMG of the quadriceps. Significant differences were noted however in the mfEMG of the hamstrings with the higher movement velocities effecting significant upward shifts in the mfEMG. Significant differences were also noted in the mfEMG of both the quadriceps and the hamstrings within the 300o.s-1 trials with the mfEMG shifting downward as the muscles fatigued. These results suggest that there is a difference in motor recruitment strategies for the hamstrings between low, moderate and high speed isokinetic activity and for the quadriceps and the hamstrings during high velocity movement.
Inertial effects on moment curves and angle of peak moment during isokinetic knee extension
Authors: Iossifidou Anna N. , Baltzopoulos Vassilios
Published: October 2018

The various isokinetic parameters are influenced by inertial moments developed during the acceleration and deceleration periods. Hence the purpose of this study was to examine inertial effects on moment versus angular displacement curves and on the angle of peak moment. Seven young adults performed 5 repetitions of concentric knee extension on the Lido isokinetic dynamometer at 30, 165 and 300 deg/s. The angular displacement and moment signals were collected and A/D converted via a 16 channel A/D card independently from the dynamometer software. Angular displacement data were smoothed using a second order Butterworth filter. The cut-off was approximately 5 Hz and was based on power spectrum assessment. Knee joint moment was calculated taking into account the inertial effects of the limb-lever arm system. Differences on the moment versus angular displacement curves were found before and after correction for the inertial effects.These differences were limited at medium to high velocities and during the initial and final parts of the movement. Angle of peak moment uncorrected and corrected for inertial effects decreased (closer to full extension) or increased (closer to full flexion) respectively as the velocity increased. It was concluded that erroneous moment curves and angle of peak moment are obtained at high velocities when the inertial effects are ignored. Therefore it is essential at high velocities to correct for inertial effects in order to obtain valid and comparable results and hence to achieve a more accurate approach to muscle and joint function assessment using these parameters.
Comparison of the power stretch machine with traditional stretching techniques for increasing low back and hamstrings flexibility
Authors: Burkett Lee N. , Seminoff Cynthia C. , Alvar Brent A.
Published: October 2018

Forty subjects (mean = 22.5 years, S.D. 2.56 years) were randomly selected who were not regularly involved in routine stretching exercises for the hamstring and low back. Subjects were compared for flexibility increase of the hamstrings and low back after a four-week training period using traditional stretching techniques and a new device, the Power Stretch. The subjects were divided randomly into three groups: (1) Group I (control 1, n = 12) which stretched with the assistance of a Certified Athletic Trainer; (2) Group II(control 2, n = 15) which stretched with no assistance and; (3) Group III(experimental, n = 13) which stretched with the Power Stretch. Flexibility was measured (after a short warm-up) using a Wells sit-and-reach box. Long-term flexibility was assessed by comparing flexibility before the four-week intervention and after the four-week intervention. The statistical results indicated there was a significant increase in long-term flexibility or all techniques, but there was no significant difference between the techniques. This study indicated that the Power Stretch was as effective as the traditional stretching techniques used in this study.
Joint angle errors in the use of isokinetic dynamometers
Authors: Sorensen H. , Zacho M. , Simonsen E.B. , Dyhre-Poulsen P. , Klausen K.
Published: October 2018

During strength measurement using isokinetic dynamometers great care is usually taken to align the anatomical joint axis to the rotation axis of the machine's lever arm. This ensures agreement between joint angular position/velocity and the corresponding measurements from the machine's potentiometer. We examined the accuracy of this correspondence during concentric knee extension with subjects sitting upright and strapped to the machine's chair. Extensions were performed at 30 dg, 120 dg and 240 dg with range of movement from 90 dgz knee flexion to full extension. We observed that due to compression of the soft tissue at the back of the thigh and elevation of the pelvis (despite strapping) the anatomical joint axis moved downward relative to the rotation axis of the lever arm. This caused discrepancies between joint angle measurements from the machine and from a knee-mounted goniometer of up to 33 dgz. These circumstances should be taken into account when muscle force-length-velocity relation studies are conducted using isokinetic machines.
Contribution of passive resistive torque to total peak concentric isokinetic torque of the calf muscle-tendon unit
Authors: Gajdosik Richard L.
Published: October 2018

The purpose of this study was to examine the contribution of the passive resistive torque to the total peak concentric isokinetic torque of the calf muscle-tendon unit. Thirty healthy, active women (age: 32 [SD 8] years) were tested using a KIN-COM 500H force dynamometer. The right calf muscle-tendon unit was first stretched passively at 5 dg from relaxed plantar flexion to the maximal angle of available dorsiflexion to measure the passive resistive torque. Subjects then performed maximal concentric plantar flexion from the maximal dorsiflexion angle at randomized test velocities of 30, 60, 120 and 180 dg. The passive resistive torque was subtracted from the total concentric peak torque to determine the active concentric peak torque. The angular delay from the onset of movement to the angle of total peak and active peak torques, and the percent contribution of the passive resistive torque to the total peak torque were calculated. One-way ANOVA procedures showed that the total and active peak torques decreased, and their respective angular delays increased, with increasing test velocities (P < 0.001). The active peak torque was less than the total peak torque (P < 0.001), and the angular delay for the active peak torque was greater than for the total peak torque among all test velocities (P < 0.001). The percent contribution of the passive resistive torque to the total peak torque ranged from 10.5% but this did not differ among the four concentric test velocities. The passive resistive torque contributed significantly to the total peak concentric torque and shifted the angular delay toward the onset of movement. The passive resistive torque contribution was essentially constant among the four test velocities, probably influenced by the decrease in concentric peak torques and the increase in the angular delay that resulted from the increasing test velocities.
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.