Intra- and interrater reliability of the establishment of one repetition maximum on squat and seated knee extension

The purpose of the present study was to develop a systematic procedure for the establishment of 1 repetition maximum (1RM) in order to describe an easily accessible test procedure that is applicable for physical therapists and athletic trainers who manage strength training for healthy individuals and patients. Another purpose was to investigate the intra- and interrater reliability of 1RM of squat on 1 leg and seated knee extension on 1 leg. Estimates of leg strength and ratings of perceived exertion formed the basis of the amount of load selected. The reliability of the procedure was assessed by a test-retest design. One RM was established for 16 and 27 healthy individuals, for squat and knee extension, respectively. The intrarater reliability of 1RM of squat on 1 leg was questionable (intraclass correlation [ICC] 0.64, measurement error 13.1 kg). The interrater reliability of 1RM of squat on 1 leg was clinically acceptable (ICC 0.94, measurement error 5.2 kg). The intrarater and interrater reliability of 1RM of seated knee extension on 1 leg was clinically acceptable (ICC 0.90, measurement error 5.1 kg and ICC 0.96, measurement error 3.2 kg, respectively). In conclusion, both exercises can be used to determine the load in exercise programs. In addition, seated knee extension may be used to evaluate strength. In contrast, squat on 1 leg is more uncertain to use at assessments between different days, which may be due to the complexity of this exercise. The test, performed in the described manner, is suitable for physical therapists, athletic trainers, and strength and conditioning coaches in clinical practice working with strength training and rehabilitation.     

NFL-225 Test to Predict 1RM Bench Press in NCAA Division I Football Players

ABSTRACT: Mann, JB, Stoner, JD, and Mayhew, JL. NFL-225 test to predict 1RM bench press in NCAA Division I football players. J Strength Cond Res 26(10): 2623-2631, 2012-The National Football League (NFL)-225 test has gained popularity for assessing muscular performance among college football programs. Although the test is a measure of absolute muscular endurance, it was reputed to be highly correlated with maximum muscular strength. The purposes of this study were to assess the predictive potential of the NFL-225 test for estimating 1 repetition maximum (1RM) bench press performance in National Collegiate Athletic Association Division I college football players and to evaluate the accuracy of previous NFL-225 prediction equations. Players (n = 289) in a successful Division I program were assessed over a period of 5 years for 1RM bench press and repetitions completed with 102.3 kg (225 lb). Test sessions occurred within 1 week of each other during the off-season training period. In a validation group (n = 202), repetitions were significantly correlated with 1RM (r = 0.95), producing a prediction equation (1RM [kg] = 103.5 + 3.08 Reps) with a standard error of estimate = 6.4 kg (coefficient of variation = 4.3%). In a randomly selected cross-validation group (n = 87), the new equation nonsignificantly underpredicted by 0.9 ± 7.2 kg produced a high correlation with actual 1RM (intraclass correlation coefficient [ICC] = 0.967), had a limit of agreement of -15.0 to 13.2 kg, and predicted 69% of the group within ±4.5 kg of their actual 1RM. The best previous equation was that of Slovak et al., which was nonsignificantly underpredicted by -0.5 ± 6.7 kg, produced a high correlation with actual 1RM (ICC = 0.975), and predicted 68% of the group within ±4.5 kg of their actual 1RM. The new NFL-225 test seems to be a reasonable predictor of 1RM bench press in Division I players but should be further assessed on players from other high-level programs.     

Test–retest reliability of cardinal plane isokinetic hip torque and EMG

The objective of the present study was to establish test–retest reliability of isokinetic hip torque and prime mover electromyogram (EMG) through the three cardinal planes of motion. Thirteen healthy young adults participated in two experimental sessions, separated by approximately one week. During each session, isokinetic hip torque was evaluated on the Biodex Isokinetic Dynamometer at a velocity of 60 deg/s. Subjects performed three maximal-effort concentric and eccentric contractions, separately, for right and left hip abduction/adduction, flexion/extension, and internal/external rotation. Surface EMGs were sampled from the gluteus maximus, gluteus medius, adductor, medial and lateral hamstring, and rectus femoris muscles during all contractions. Intraclass correlation coefficients (ICC – 2,1) and standard errors of measurement (SEM) were calculated for peak torque for each movement direction and contraction mode, while ICCs were only computed for the EMG data. Motions that demonstrated high torque reliability included concentric hip abduction (right and left), flexion (right and left), extension (right) and internal rotation (right and left), and eccentric hip abduction (left), adduction (left), flexion (right), and extension (right and left) (ICC range = 0.81–0.91). Motions with moderate torque reliability included concentric hip adduction (right), extension (left), internal rotation (left), and external rotation (right), and eccentric hip abduction and adduction (right), flexion (left), internal rotation (right and left), and external rotation (right and left) (ICC range = 0.49–0.79). The majority of the EMG sampled muscles (n = 12 and n = 11 for concentric and eccentric contractions, respectively) demonstrated high reliability (ICC = 0.81–0.95). Instances of low, or unacceptable, EMG reliability values occurred for the medial hamstring muscle of the left leg (both contraction modes) and the adductor muscle of the right leg during eccentric internal rotation. The major finding revealed high and moderate levels of between-day reliability of isokinetic hip peak torque and prime mover EMG. It is recommended that the day-to-day variability estimates concomitant with acceptable levels of reliability be considered when attempting to objectify intervention effects on hip muscle performance.     

Shoulder strength and range-of-motion characteristics in bodybuilders

The purpose of this study was to compare shoulder range-of-motion (ROM) and strength values between bodybuilders and nonbodybuilders. Fifty-four men (29 bodybuilders and 25 nonbodybuilders) between the ages of 21 and 34 years participated in the study. Goniometric measurements were used to assess shoulder flexion and internal and external rotation ROM. Isometric manual muscle tests were performed using a handheld dynamometer. Shoulder flexion, internal and external rotation, abduction, and prone shoulder retraction and elevation strength were tested. Independent t-tests were used to determine levels of statistical significance between the groups. Bodybuilders showed an overall loss of shoulder rotation ROM (166 degrees vs. 180 degrees ) and a significantly decreased internal rotation ROM (-11 degrees ) compared with the control group. Bodybuilders were significantly stronger on all isometric shoulder-strength tests than nonbodybuilders, except for the assessment of lower trapezius strength when expressed as a percentage of body weight. The results of this study indicate that bodybuilders have imbalances regarding strength and ROM at the shoulder that may make them susceptible to shoulder pathology.     

A single video camera postural assessment system to measure rotation of the shoulder during computer use

The goal of this study was to evaluate the performance of a single video camera system for measuring shoulder rotation during computer work, and to quantify the work and postural space within which the system performs optimally. Shoulder rotation angles calculated using the video system were compared with angles calculated using an active infrared LED three-dimensional motion analysis system while 10 adult volunteers simulated postures for two different trials: typical of normal computer work (freestyle) and with forced shoulder abduction (constrained). Average and absolute errors were calculated to determine the accuracy and precision of the system, respectively, for each trial, for each position, and for both the right and left hands. For the right hand, mean values for the average and absolute errors were -1 and 0 degrees, respectively. Only the absolute error increased significantly to 12 degrees for the constrained posture compared with freestyle. During normal computer work, the video system provided shoulder rotation angle values similar to those of a three-dimensional system, thus making it a viable and simple instrument to use in field studies.     

Evaluation of inter- and intra-observer variations in prostate gland delineation using CT-alone versus CT/TPUS

BackgroundThis study aims to explore the role of four-dimensional (4D) transperineal ultrasound (TPUS) in the contouring of prostate gland with planning computed tomography (CT) images, in the absence of magnetic resonance imaging (MRI).Materials and methodsFive radiation oncologists (ROs) performed two rounds of prostate gland contouring (single-blinded) on CT-alone and CT/TPUS datasets obtained from 10 patients who underwent TPUS-guided external beam radiotherapy. Parameters include prostate volume, DICE similarity coefficient (DSC) and centroid position. Wilcoxon signed-rank test assessed the significance of inter-modality differences, and the intraclass correlation coefficient (ICC ) reflected inter- and intra-observer reliability of parameters.ResultsInter-modality analysis revealed high agreement (based on DSC and centroid position) of prostate gland contours between CT-alone and CT/TPUS. Statistical significant difference was observed in the superior-inferior direction of the prostate centroid position (p = 0.011). All modalities yielded excellent inter-observer reliability of delineated prostate volume with ICC > 0.9, mean DSC > 0.8 and centroid position: CT-alone (ICC = 1.000) and CT/TPUS (ICC = 0.999) left-right (L/R); CT-alone (ICC = 0.999) and CT/TPUS (ICC = 0.998) anterior-posterior (A/P); CT-alone (ICC = 0.999) and CT/TPUS (ICC = 1.000) superior-inferior (S/I). Similarly, all modalities yielded excellent intra-observer reliability of delineated prostate volume, ICC > 0.9 and mean DSC > 0.8. Lastly, intra-observer reliability was excellent on both imaging modalities for the prostate centroid position, ICC > 0.9.ConclusionTPUS does not add significantly to the amount of anatomical information provided by CT images. However, TPUS can supplement planning CT to achieve a higher positional accuracy in the S/I direction if access to CT/MRI fusion is limited.     

The validity and reliability of the 1RM bench press using chain-loaded resistance

The purposes of this study were to determine the validity and test-retest reliability of the 1 repetition maximum (1RM) chain-loaded, free-weight bench press (CBP) and to examine possible learning effects that may occur between the test-retest measurements. Nine resistance-trained men (20.58 +/- 1.31 years, 188.24 +/- 9.29 cm, 92.07 +/- 16.94 kg) and seven resistance-trained women (20.42 +/- 0.98 years, 175.61 +/- 9.32 cm, 73.61 +/- 10.80 kg) participating in Division II college basketball completed this study. Two familiarization sessions took place using light to moderate loads to learn proper technique. The subjects completed a 1RM test on the traditional plate-loaded bench press 4 days before completion of the CBP 1RM, which was followed by 4 days of rest before completing the retest. Intraclass correlation coefficients (ICC) and the percent coefficients of variation (CV) were used to determine relative and absolute test-retest reliability. Concurrent validity was determined from the Pearson correlation coefficients between the CBP and the plate-loaded bench press. Test-retest differences were analyzed with the paired t-test. ICC and CV for the men (r = 0.99, 1.4%) and women (r = 0.93, 3.5%), respectively indicate that highly reproducible 1RM scores can be found with the CBP. High validity was also found with high correlations between the CBP and plate-loaded bench press for the men (r = 0.95) and women (r = 0.80). A statistically significant (p = 0.04) but clinically small (2.57 kg) shift in the mean occurred between the CBP test and retest for the men, whereas no change occurred for the women. The data indicate that valid and reliable 1RM scores can be found after two familiarization sessions in men and women athletes who have previous resistance training experience.     

In vivo assessment of muscle fascicle length by extended field-of-view ultrasonography

The present study examined the reliability and validity of in vivo vastus lateralis (VL) fascicle length (L(f)) assessment by extended field-of-view ultrasonography (EFOV US). Intraexperimenter and intersession reliability of EFOV US were tested. Further, L(f) measured from EFOV US images were compared to L(f) measured from static US images (6-cm FOV) where out-of-field fascicle portions were trigonometrically estimated (linear extrapolation). Finally, spatial accuracy of the EFOV technique was assessed by comparing L(f) measured on swine VL by EFOV US to actual measurements from digital photographs. The difference between repeated VL L(f) measurements by the same experimenter was 2.1 ± 1.7% with an intraclass correlation (ICC) of 0.99 [95% confidence interval (CI) = 0.95-1.00]. In terms of intersession reliability, no difference (P = 0.48) was observed between L(f) measured on two different occasions, with ICC = 0.95 (CI = 0.80-0.99). The average absolute difference between L(f) measured by EFOV US and using linear extrapolation was 12.6 ± 8.1% [ICC = 0.76 (CI = -0.20-0.94)]; EFOV L(f) was always longer than extrapolated L(f). The relative error of measurement between L(f) measured by EFOV US and by dissective assessment (digital photographs) in isolated swine VL was 0.84% ± 2.6% with an ICC of 0.99 (CI = 0.94-1.00). These results show that EFOV US is a reliable and valid method for the measurement of long muscle fascicle in vivo. Thus EFOV US analysis was proven more accurate for the assessment of skeletal muscle fascicle length than conventional extrapolation methods.     

Measurement of Shoulder Range of Motion in Patients with Adhesive Capsulitis Using a Kinect

Range of motion (ROM) measurements are essential for the evaluation for and diagnosis of adhesive capsulitis of the shoulder (AC). However, taking these measurements using a goniometer is inconvenient and sometimes unreliable. The Kinect (Microsoft, Seattle, WA, USA) is gaining attention as a new motion detecting device that is nonintrusive and easy to implement. This study aimed to apply Kinect to measure shoulder ROM in AC; we evaluated its validity by calculating the agreement of the measurements obtained using Kinect with those obtained using goniometer and assessed its utility for the diagnosis of AC. Both shoulders of 15 healthy volunteers and affected shoulders of 12 patients with AC were included in the study. The passive and active ROM of each were measured with a goniometer for flexion, abduction, and external rotation. Their active shoulder motions for each direction were again captured using Kinect and the ROM values were calculated. The agreement between the two measurements was tested with the intraclass correlation coefficient (ICC). Diagnostic performance using the Kinect ROM was evaluated with Cohen’s kappa value. The cutoff values of the limited ROM were determined in the following ways: the same as passive ROM values, reflecting the mean difference, and based on receiver operating characteristic curves. The ICC for flexion/abduction/external rotation between goniometric passive ROM and the Kinect ROM were 0.906/0.942/0.911, while those between active ROMs and the Kinect ROMs were 0.864/0.932/0.925. Cohen’s kappa values were 0.88, 0.88, and 1.0 with the cutoff values in the order above. Measurements of the shoulder ROM using Kinect show excellent agreement with those taken using a goniometer. These results indicate that the Kinect can be used to measure shoulder ROM and to diagnose AC as an alternative to goniometer.     

Reliability of the one-repetition-maximum power clean test in adolescent athletes

Although the power clean test is routinely used to assess strength and power performance in adult athletes, the reliability of this measure in younger populations has not been examined. Therefore, the purpose of this study was to determine the reliability of the 1-repetition maximum (1RM) power clean in adolescent athletes. Thirty-six male athletes (age 15.9 ± 1.1 years, body mass 79.1 ± 20.3 kg, height 175.1 ±7.4 cm) who had >1 year of training experience in weightlifting exercises performed a 1RM power clean on 2 nonconsecutive days in the afternoon following standardized procedures. All test procedures were supervised by a senior level weightlifting coach and consisted of a systematic progression in test load until the maximum resistance that could be lifted for 1 repetition using proper exercise technique was determined. Data were analyzed using an intraclass correlation coefficient (ICC[2,k]), Pearson correlation coefficient (r), repeated measures analysis of variance, Bland-Altman plot, and typical error analyses. Analysis of the data revealed that the test measures were highly reliable demonstrating a test-retest ICC of 0.98 (95% confidence interval = 0.96-0.99). Testing also demonstrated a strong relationship between 1RM measures in trials 1 and 2 (r = 0.98, p < 0.0001) with no significant difference in power clean performance between trials (70.6 ± 19.8 vs. 69.8 ± 19.8 kg). Bland-Altman plots confirmed no systematic shift in 1RM between trials 1 and 2. The typical error to be expected between 1RM power clean trials is 2.9 kg, and a change of at least 8.0 kg is indicated to determine a real change in lifting performance between tests in young lifters. No injuries occurred during the study period, and the testing protocol was well tolerated by all the subjects. These findings indicate that 1RM power clean testing has a high degree of reproducibility in trained male adolescent athletes when standardized testing procedures are followed and qualified instruction is present.     

Internal consistency and test–retest reliability of an instrumented functional reaching task using wireless electromyographic sensors

The purpose of this study was to establish the internal consistency and test–retest reliability of the electromyographic and accelerometric data sampled from the prime movers of the dominant arm during an antigravity, within-arm’s length stand-reaching task without trunk restraint. Ten healthy young adults participated in two experimental sessions, approximately 7–10 days apart. During each session, subjects performed 15 trials of both a flexion- and an abduction-reaching task. Surface EMG and acceleration using wireless sensors were sampled from the anterior and middle deltoid. Reliability was established using Cronbach’s alpha, intraclass correlation coefficients (ICC 2, k) and standard error of measurements (SEM) for electromyographic reaction time, burst duration and normalized amplitude along with peak acceleration. Results indicated high degrees of inter-trial and test–retest reliability for flexion (Cronbach’s α range = 0.92–0.99; ICC range = 0.82–0.92) as well as abduction (Cronbach’s α range = 0.94–0.99; ICC range = 0.81–0.94) reaching. The SEM associated with response variables for flexion and abduction ranged from 1.55–3.26% and 3.33–3.95% of means, respectively. Findings from this study revealed that electromyographic and accelerometric data collected from prime movers of the arm during the relatively functional stand-reaching task were highly reproducible. Given its high reliability and portability, the proposed test could have applications in clinical and laboratory settings to quantify upper limb function.     

Ageing and joint position sense of the asymptomatic shoulder: An observational study

PurposeThis study aimed to quantify the extent to which age was associated with joint position sense (JPS) of the asymptomatic shoulder as measured by joint position reproduction (JPR) tasks and assess the reproducibility of these tasks.Methods120 Asymptomatic participants aged 18–70 years each performed 10 JPR-tasks. Both contralateral and ipsilateral JPR-tasks were evaluated on accuracy of JPR under active- and passive conditions at two levels within the shoulder forward flexion trajectory. Each task was performed three times. In a subgroup of 40 participants, the reproducibility of JPR-tasks was assessed one week after initial measurement. Reproducibility of JPR-tasks was evaluated by both reliability (intra-class correlation coefficients (ICC’s)) and agreement (standard error of measurement (SEM)) measures.ResultsAge was not associated with increased JPR-errors for any of the contralateral or ipsilateral JPR-tasks. ICC’s ranged between 0.63 and 0.80 for contralateral JPR-tasks, and from 0.32 to 0.48 for ipsilateral tasks, except for one ipsilateral task where the reliability was similar to contralateral tasks (0.79). The SEM was comparable and small for all JPR-tasks, ranging between 1.1 and 2.1.ConclusionNo age-related decline in JPS of the asymptomatic shoulder was found, and good agreement between test and re-test measurements for all JPR-tasks as indicated by the small SEM.     

Between-session reliability of opto-electronic motion capture in measuring sagittal posture and 3-D ranges of motion of the thoracolumbar spine

This study evaluated between-session reliability of opto-electronic motion capture to measure trunk posture and three-dimensional ranges of motion (ROM). Nineteen healthy participants aged 24–74 years underwent spine curvature, pelvic tilt and trunk ROM measurements on two separate occasions. Rigid four-marker clusters were attached to the skin overlying seven spinous processes, plus single markers on pelvis landmarks. Rigid body rotations of spine marker clusters were calculated to determine neutral posture and ROM in flexion, extension, total lateral bending (left-right) and total axial rotation (left-right). Segmental spine ROM values were in line with previous reports using opto-electronic motion capture. Intraclass correlation coefficients (ICC) and standard error of measurement (SEM) were calculated as measures of between-session reliability and measurement error, respectively. Retroreflective markers showed fair to excellent between-session reliability to measure thoracic kyphosis, lumbar lordosis, and pelvic tilt (ICC = 0.82, 0.63, and 0.54, respectively). Thoracic and lumbar segments showed highest reliabilities in total axial rotation (ICC = 0.78) and flexion-extension (ICC = 0.77–0.79) ROM, respectively. Pelvic segment showed highest ICC values in flexion (ICC = 0.78) and total axial rotation (ICC = 0.81) trials. Furthermore, it was estimated that four or fewer repeated trials would provide good reliability for key ROM outcomes, including lumbar flexion, thoracic and lumbar lateral bending, and thoracic axial rotation. This demonstration of reliability is a necessary precursor to quantifying spine kinematics in clinical studies, including assessing changes due to clinical treatment or disease progression.     

Intra-articular distension and steroids in the management of capsulitis of the shoulder.

OBJECTIVE--To determine whether there is any synergistic effect in the administration of intraarticular steroids with distension in the management of early capsulitis of the shoulder. DESIGN--Prospective randomised trial of three treatments--namely distension only, steroid only, and steroid with distension. SETTING--Academic department of orthopaedic and accident surgery at Queen''s Medical Centre, Nottingham. SUBJECTS--47 patients (30 women) with capsulitis affecting 50 shoulders. INTERVENTIONS--Three intra-articular injections into the shoulder given at six week intervals by the same technique. MAIN OUTCOME MEASURES--Passive range of abduction, forward flexion, and external rotation; results of shoulder dynamometry measuring work done and torque produced; pain levels at rest and with resisted movement. RESULTS--All patients reported improvement during the study. Analysis of the mean improvements in abduction and forward flexion showed these to be significantly greater in the steroid with distension and steroid only groups than in the distension only group (mean improvements in abduction (degrees/week (95% confidence interval)) 4.3 (3.4 to 5.2), 3.4 (2.4 to 4.5), and 1.0 (-0.8 to 2.8) in the three groups respectively; mean improvements in flexion (degrees/week (95% confidence interval)) 3.6 (3.2 to 4.0), 3.3 (2.3 to 4.3), and 1.5 (0.5 to 2.5) respectively). Shoulder dynamometry failed to show a significant difference among the treatment groups. No severe complications occurred as a result of the injections, but two patients reported facial flushing related to the use of steroids. CONCLUSION--Intra-articular steroid injections have a useful role in the outpatient management of early capsulitis.     

Limited forearm motion compensated by thoracohumeral kinematics when performing tasks requiring pronation and supination

This study investigates the altered thoracohumeral kinematics when forearm rotation is restricted while performing five activities requiring pronation and supination. Two splints simulated both a fixed-supinated or fixed-neutral forearm in six healthy subjects; the three-dimensional coupled relationship among motion about the forearm, elbow, and shoulder were analyzed. In using a screwdriver, the normal range of forearm rotation of 77.6° (SD = 30.8°) was reduced in the fixed-supinated to 11.3° (SD = 2.9°) and fixed-neutral to 18.2° (SD = 6.2°). This restriction from the fixed-supinated and fixed-neutral forearms was compensated at the shoulder by a significant increase in the total range of (1) ad/abduction by 57.3° and 62.8° respectively (p < .001), (2) forward-reverse flexion (24.3° and 18.2° respectively; p < .05) and (3) internal-external rotation (37.1° and 44.2° respectively; p < .001). A similar result was demonstrated for the doorknob activity. The elbow did not significantly contribute to forearm rotation (p = .14), and is believed to be due to the elbow axis being orthogonal and oblique to the forearm axis. For open kinetic-chain activities, with a fixed-supinated forearm performing there was a significant coupled increase in ad/abduction (p < .05) and int/external rotation (p < .05) for the phone and feeding tasks, with the phone task also having a significantly increased forward shoulder flexion (p < .05). For the fixed-neutral forearm, significant compensatory movement was only seen in the feeding task with increased ad/abduction and internal-external shoulder rotation (p < .05) and the card inserting task with increased ad/abduction and forward-reverse shoulder flexion. Limited forearm function requires compensatory motion from adjacent joints to perform activities that require pronation and supination.     

The effect of head position, electrode site, movement and smoothing window in the determination of a reliable maximum voluntary activation of the upper trapezius muscle.

Quantitative measures derived from raw myoelectric signal (MES) data must be normalized to allow for comparisons both within and between subjects. The most common method of normalization involves dividing the root mean square (RMS) amplitude of the MES recorded during a given activity by the RMS of the MES elicited during a maximal voluntary isometric contraction (MVIC) of that particular muscle. The objective of this study was to use surface-recorded MES amplitude to determine the combination of electrode site, test position, head posture, and smoothing window that elicits the highest and most reliable MES amplitudes during an MVIC of the upper trapezius (UT) muscle. Ten volunteers had surface electrodes positioned at five sites on the UT of their dominant side. Three trials of each of three MVIC test positions were performed both with the head in neutral and rotated 45 degrees to the contralateral side. A repeated-measures ANOVA was used for statistical hypothesis testing. Coefficients of variation were used to quantify the between-factor variability introduced in each case. In addition, the data were re-analyzed using moving windows of 100 to 500 ms in length, and an ANOVA was used to determine the effect of window length on both the amplitude and variability of the estimates of maximum voluntary activation (MVE). Head position had no significant effect on RMS amplitude of the MVIC in any of the test positions. There was a significant electrode site by test position interaction effect. Bonferroni post-hoc analyses were performed on this interaction by fixing test position and testing electrode site, revealing that Sites 1 (2 cm lateral to the midpoint between C7 spinous process and the posterolateral border of the acromion) and 4 (2 cm posterior to Site 1) recorded significantly higher RMS values for all test positions, and were not significantly different from each other. Fixing electrode site, the test position analysis revealed that abduction of the humerus, and abduction with external rotation of the humerus produced significantly higher RMS values than shoulder elevation at both Sites 1 and 4, and that abduction produced a significantly higher RMS amplitude than abduction in external rotation at Site 1. The results confirmed that Sites 1 and 4 consistently produced the highest MES amplitudes for all movements. Pure abduction consistently elicited maximal RMS values; however there is concern regarding supraspinatus cross talk during this movement. Site 1 was found to produce the most reliable data. A moving window of 100 ms was found to generate MVE estimates that were significantly higher than windows ranging from 200 ms to 500 ms in length. There was no effect of window length on the reliability of the MVEs. Based on this study, it was concluded that abduction or abduction with the arms in lateral rotation should be used as normalization contraction positions for the upper trapezius muscle. During this movement, Site 1 data smoothed with a moving window of 100 ms produces the highest amplitude MVE data but window lengths greater than 200 ms produce more stable estimates in terms of being able to compare studies in which moving windows are used to compute RMS.     

The range of axial rotation of the glenohumeral joint

There is a paucity of data in the literature on the restraining effects of the glenohumeral (GH) ligaments; cadaveric testing is one of the best methods for determining the function of these types of tissues. The aim of this work was to commission a custom-made six degrees of freedom (dof) joint loading apparatus and to establish a protocol for laxity testing of cadaveric shoulder specimens. Nine cadaveric shoulder specimens were used in this study and each specimen had all muscle resected leaving the scapula, humerus (transected at mid-shaft) and GH capsule. Specimens were mounted on the testing apparatus with the joint in the neutral position and at 30°, 60° and 90° GH abduction in the coronal, scapula and 30° forward flexion planes. For each orientation, 0–1 N m in 0.1 N m increments was applied in internal/external rotation and the angular displacement recorded. The toe-region of the moment–displacement curves ended at approximately ±0.5 N m. The highest rotational range of motion for the joint was 140° for ±1.0 N m at 30° GH abduction in the scapula plane. The range of motion shifted towards external rotation with increasing levels of abduction. The results provide the optimum loading regime to pre-condition shoulder specimens and minimise viscoelastic effects in the ligaments prior to laxity testing (>0.5 N m at 30° GH abduction in any of the three planes). Knowledge of the mechanical properties of the GH capsuloligamentous complex has implications for modelling of the shoulder as well surgical planning and intervention.     

A kinetic and electromyographic comparison of the standing cable press and bench press

This study compared the standing cable press (SCP) and the traditional bench press (BP) to better understand the biomechanical limitations of pushing from a standing position together with the activation amplitudes of trunk and shoulder muscles. A static biomechanical model (4D Watbak) was used to assess the forces that can be pushed with 2 arms in a standing position. Then, 14 recreationally trained men performed 1 repetition maximum (1RM) BP and 1RM single-arm SP exercises while superficial electromyography (EMG) of various shoulder and torso muscles was measured. The 1RM BP performance resulted in an average load (74.2 +/- 17.6 kg) significantly higher than 1RM single-arm SP (26.0 +/- 4.4 kg). In addition, the model predicted that pushing forces from a standing position under ideal mechanical conditions are limited to 40.8% of the subject's body weight. For the 1RM BP, anterior deltoid and pectoralis major were more activated than most of the trunk muscles. In contrast, for the 1RM single-arm SP, the left internal oblique and left latissimus dorsi activities were similar to those of the anterior deltoid and pectoralis major. The EMG amplitudes of pectoralis major and the erector muscles were larger for 1RM BP. Conversely, the activation levels of left abdominal muscles and left latissimus dorsi were higher for 1RM right-arm SP. The BP emphasizes the activation of the shoulder and chest muscles and challenges the capability to develop great shoulder torques. The SCP performance also relies on the strength of shoulder and chest musculature; however, it is whole-body stability and equilibrium together with joint stability that present the major limitation in force generation. Our EMG findings show that SCP performance is limited by the activation and neuromuscular coordination of torso muscles, not maximal muscle activation of the chest and shoulder muscles. This has implications for the utility of these exercise approaches to achieve different training goals.