Test-retest reliability of the five-repetition sit-to-stand test: a systematic review of the literature involving adults

The 5-repetition sit-to-stand test (FRSTST) is a widely used measure of functional strength, particularly among older adults. The purpose of this review was to summarize the findings of research using the intraclass correlation coefficient (ICC) to describe the test-retest reliability of the FRSTST. A search of 3 electronic databases and hand searches were used to identify relevant articles. Information on the subjects, test sessions and the ICCs reported was abstracted from the articles. The searches identified 10 relevant articles. The ICCs reported in the articles ranged from 0.64 to 0.96. The adjusted mean ICC calculated from the reported ICCs was 0.81. The test-retest reliability of the FRSTST can be interpreted as good to high in most populations and settings.     

The effect of the partially restricted sit-to-stand task on biomechanical variables in subjects with and without Parkinson’s disease

The aim of this study was to explore the electromyographic, kinetic and kinematic patterns during a partially restricted sit-to-stand task in subjects with and without Parkinson’s disease (PD). If the trunk is partially restricted, different behavior of torques and muscle activities could be found and it can serve as a reference of the deterioration in the motor performance of subjects with PD. Fifteen subjects participated in this study and electromyography (EMG) activity of the tibialis anterior (TA), soleus (SO), vastus medialis oblique (VMO), biceps femoris (BF) and erector spinae (ES) were recorded and biomechanical variables were calculated during four phases of the movement. Subjects with PD showed more flexion at the ankle, knee and hip joints and increased knee and hip joint torques in comparison to healthy subjects in the final position. However, these joint torques can be explained by the differences in kinematic data. Also, the hip, knee and ankle joint torques were not different in the acceleration phase of movement. The use of a partially restricted sit-to-stand task in PD subjects with moderate involvement leads to the generation of joint torques similar to healthy subjects. This may have important implications for rehabilitation training in PD subjects.     

Sensor-to-body calibration procedure for clinical motion analysis of lower limb using magnetic and inertial measurement units

Magnetic and Inertial measurement units (MIMUs) have become exceedingly popular for ambulatory human motion analysis during the past two decades. However, measuring anatomically meaningful segment and joint kinematics requires virtual alignment of the MIMU frame with the anatomical frame of its corresponding segment. Therefore, this paper presents a simple calibration procedure, based on MIMU readouts, to align the inertial frame of the MIMU with the anatomical frames, as recommended by ISB. The proposed calibration includes five seconds of quiet standing in a neutral posture followed by ten consecutive hip flexions/extensions. This procedure will independently calibrate MIMUs attached to the pelvis, thigh, shank, and foot. The accuracy and repeatability of the calibration procedure and the 3D joint angle estimation were validated against the gold standard motion capture system by an experimental study with ten able-bodied participants. The procedure showed high test-retest repeatability in aligning the MIMU frame with its corresponding anatomical frame, i.e., the helical angle between the MIMU and anatomical frames did not significantly differ between the test and retest sessions (except for thigh MIMU). Compared to previously introduced procedures, this procedure attained the highest inter-participant repeatability (inter-participant coefficient of variations of the helical angle: 20.5–42.2%). Further, the proposed calibration would reduce the offset errors of the 3D joint angle estimation (up to 12.8 degrees on average) compared to joint angle estimation without calibration (up to 26.3 degrees on average). The proposed calibration enables MIMU to measure clinically meaningful gait kinematics.     

Comparative Analysis of Linear and Nonlinear Methods of Estimating the Pseudo-Second-Order Kinetic Parameters for Sorption of Malachite Green onto Pretreated Rice Husk

Batch sorption experiments were carried out for removal of malachite green from aqueous solution using pretreated rice husk. The equilibrium kinetic data were analyzed using pseudo-second-order kinetic model. A comparison between linear and nonlinear methods of estimating the kinetic parameters was carried out. Four pseudo-second-order kinetic linear equations were discussed. The coefficient of determination (r ²) and chi-square (χ²) test were employed as error analysis methods to determine the best-fitting equation. The results show that nonlinear method is a better alternative to obtain the kinetic parameters. In addition, the chi-square test was a better method to determine the best-fitting model.     

Reliability of electromyographic normalization methods for evaluating the hip musculature.

The purpose of this study was to determine the reliability of three normalization methods for analyzing hip abductor activation during rehabilitation exercises. Thirteen healthy subjects performed three open kinetic chain and three closed kinetic chain hip abductor exercises. Surface EMG activity for the gluteus medius was collected during each exercise and normalized based on a maximum voluntary isometric contraction (MVIC), mean dynamic (m-DYN), and peak dynamic activity (pk-DYN). Intraclass coefficient correlations (ICCs), intersubject coefficients of variation (CVs), and intrasubject CVs were then calculated for each normalization method. MVIC ICCs exceeded 0.93 for all exercises. M-DYN and pk-DYN ICCs exceeded 0.85 for all exercises except for the sidelying abduction exercise. Intersubject CVs ranged from 55% to 77% and 19% to 61% for the MVIC and dynamic methods, respectively. Intrasubject CVs ranged from 11% to 22% for all exercises under all normalization methods. The MVIC method provided the highest measurement reliability for determining differences in activation amplitudes between hip abductor exercises in healthy subjects. Future research should determine if these same results would apply to a symptomatic patient population.     

Reliability of performance velocity for jump squats under feedback and nonfeedback conditions

Randell, AD, Cronin, JB, Keogh, JWL, Gill, ND, and Pedersen, MC. Reliability of performance velocity for jump squats under feedback and nonfeedback conditions. J Strength Cond Res 25(12): 3514-3518, 2011-Advancements in the monitoring of kinematic and kinetic variables during resistance training have resulted in the ability to continuously monitor performance and provide feedback during training. If equipment and software can provide reliable instantaneous feedback related to the variable of interest during training, it is thought that this may result in goal-oriented movement tasks that increase the likelihood of transference to on-field performance or at the very least improve the mechanical variable of interest. The purpose of this study was to determine the reliability of performance velocity for jump squats under feedback and nonfeedback conditions over 3 consecutive training sessions. Twenty subjects were randomly allocated to a feedback or nonfeedback group, and each group performed a total of 3 "jump squat" training sessions with the velocity of each repetition measured using a linear position transducer. There was less change in mean velocities between sessions 1-2 and sessions 2-3 (0.07 and 0.02 vs. 0.13 and -0.04 m·s), less random variation (TE = 0.06 and 0.06 vs. 0.10 and 0.07 m·s) and greater consistency (intraclass correlation coefficient = 0.83 and 0.87 vs. 0.53 and 0.74) between sessions for the feedback condition as compared to the nonfeedback condition. It was concluded that there is approximately a 50-50 probability that the provision of feedback was beneficial to the performance in the squat jump over multiple sessions. It is suggested that this has the potential for increasing transference to on-field performance or at the very least improving the mechanical variable of interest.     

Energy expenditure of bipedal walking is higher than that of quadrupedal walking in Japanese macaques

The authors previously compared energetic costs of bipedal and quadrupedal walking in bipedally trained macaques used for traditional Japanese monkey performances (Nakatsukasa et al. 2004 Am. J. Phys. Anthropol. 124:248-256). These macaques used inverted pendulum mechanics during bipedal walking, which resulted in an efficient exchange of potential and kinetic energy. Nonetheless, energy expenditure during bipedal walking was significantly higher than that of quadrupedal walking. In Nakatsukasa et al. (2004 Am. J. Phys. Anthropol. 124:248-256), locomotor costs were measured before subjects reached a steady state due to technical limitations. The present investigation reports sequential changes of energy consumption during 15 min of walking in two trained macaques, using carbon dioxide production as a proxy of energy consumption, as in Nakatsukasa et al. (2004 Am. J. Phys. Anthropol. 124:248-256). Although a limited number of sessions were conducted, carbon dioxide production was consistently greater during bipedal walking, with the exception of some irregularity during the first minute. Carbon dioxide production gradually decreased after 1 min, and both subjects reached a steady state within 10 min. Energy expenditure during bipedalism relative to quadrupedalism differed between the two subjects. It was considerably higher (140% of the quadrupedal walking cost) in one subject who walked with more bent-knee, bent-hip gaits. This high cost strongly suggests that ordinary macaques, who adopt further bent-knee, bent-hip gaits, consume a far greater magnitude of energy during bipedal walking.     

A power equation for the sprint in speed skating.

An analysis of the start of the 500 m speed skating races during the 1988 Olympic Winter Games showed a remarkably high correlation between the acceleration of the skater in the first second of the sprint and the final time (r = -0.75). In this study a power equation is used to explain this high coefficient of correlation. The performance in speed skating is determined by the capability of external power production by the speed skater. This power is necessary to overcome the air and ice friction and to increase the kinetic energy of the skater. Numerical values of the power dissipated to air and ice friction, both dependent on speed, are obtained from ice friction and wind tunnel experiments. Using aerobic and anaerobic power production as measured during supra maximal bicycle tests of international-level speed skaters, a model of the kinetics of power production is obtained. Simulation of power production and power dissipation yields values of speed and acceleration and, finally, the performance time of the sprint during speed skating. The mean split time at 100 m and the final time at 500 m in these races, derived from simulation, were 10.57 s (+/- 0.31) and 37.82 s (+/- 0.96), respectively. The coefficient of correlation between the simulated 500 m times and the actual 500 m times was 0.90. From the results of this study it can be concluded that the distribution of the available anaerobic energy is an important factor in the short lasting events. For the same amount of anaerobic energy the better sprinters appear to be able to liberate considerably more energy at the onset of the race than skaters of lower performance level.     

Joint moment work during the stance-to-swing transition in hemiparetic subjects

Following stroke many individuals are left with neurological and functional deficits, including hemiparesis, which impair their ability to walk. Our previous work reported that propulsion of the paretic leg during pre-swing is impaired and may limit gait speed and knee flexion during swing. To elucidate the mechanism of this impairment, we assessed the mechanical work produced by the hip, knee, and ankle moments during pre-swing of the paretic limb in a group of stroke subjects and compared it with the work produced by non-disabled controls walking at similar speeds. Kinematic and kinetic gait data were collected from 23 hemiparetic and 10 control subjects. The hemiparetic subjects walked at their self-selected speeds. The controls walked at their self-selected and two or three slower speeds. Even when compared to controls walking at slow speeds, ankle plantarflexor work during pre-swing was greatly reduced (-0.136+/-0.062J/kg) in the hemiparetic subjects. Differences in hip (+0.006+/-0.020J/kg) and knee (+0.040+/-0.026J/kg) moment work partially offset the reduction in ankle work, but net joint moment work was still significantly reduced (-0.088+/-0.056J/kg). The reduction in work accounts for the low energy of the paretic limb at the stance-to-swing transition previously reported. Future investigation is needed to determine if targeted training of the plantarflexors in the paretic limb improves swing-phase function and locomotor performance in hemiparetic individuals.     

The variability and complexity of sitting postural control are associated with discomfort

The present investigation examined the variability of sitting postural movement in relation to the development of perceived discomfort by means of linear and nonlinear analysis. Nine male subjects participated in this study. Discomfort ratings, kinetic and kinematics data were recorded during prolonged sitting. Body part discomfort index, displacement of the center of pressure (COP) in anterior–posterior and medial–lateral directions as well as lumbar curvature were calculated. Mean, standard deviation and sample entropy values were extracted from COP and lumbar curvature signals. Standard deviation and sample entropy were used to assess the degree of variability and complexity of sitting. A correlation analysis was performed to determine the correlation of each parameter with discomfort. There were no correlations between discomfort and any of the mean values. On the contrary, the standard deviations of the COP displacement in both directions and lumbar curvature were positively correlated to discomfort, whereas sample entropies were negatively correlated. The present study suggests that the increase in degree of variability and the decrease in complexity of sitting postural control are interrelated with the increase in perceived discomfort. Finally, the present study underlined the importance of quantifying motor variability for understanding the biomechanics of seated posture.     

Adsorption of methylene blue from aqueous solution on pyrolyzed petrified sediment

The adsorption kinetics of methylene blue on pyrolyzed petrified sediment (PPS) has been performed using a batch-adsorption technique. The effects of various experimental parameters, such as initial dye concentration, contact time, and temperature were investigated. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data. The best correlation coefficient was obtained using the pseudo first-order kinetic model, which shows that the adsorption of methylene blue followed the pseudo-first-order rate expression and the rate constants were evaluated. The Langmuir and Freundlich adsorption isotherm models were applied to describe the equilibrium isotherms and the isotherm constants were determined. It was found that the data fitted well to Langmuir and Freundlich models. The activation energy of adsorption was also evaluated for the adsorption of methylene blue onto pyrolyzed sediment. It was found about 8.5 kJ mol(-1). Thermodynamics parameters DeltaG(o), DeltaH(o), DeltaS(o) were calculated, indicating that this process can be spontaneous and endothermic. The adsorption enthalpy and entropy were found as 14-18.5 kJ mol(-1) and 52.8-67 J mol(-1) K(-1), respectively. The results obtained from the adsorption process using PPS as adsorbent was subjected to student's t-test.     

The potential application of FT-Raman spectroscopy for the quantification and mapping of the steroidal glycoside P57 in Hoodia gordonii

Hoodia gordonii, with the perceived active ingredient P57 (a steroidal glycoside), is a succulent plant which has gained commercial popularity as an anti-obesity preparation. The content of P57 is used as an indication of the quality of the raw material. Traditionally, quantification of P57 is performed using liquid-chromatography coupled to mass spectrometry (LC–MS) which is expensive and laborious. Vibrational spectroscopy methods such as FT-Raman spectroscopy offer a simple, less expensive and rapid alternative. The potential of FT-Raman to quantify and identify the location of P57 in H. gordonii raw plant material was investigated. LC–MS was used to determine the concentration of P57 in 145 plant samples and the data was used to develop a calibration model with chemometric techniques based on the partial least squares projections to latent structures (PLS) algorithm. The performance of the calibration model was evaluated according to the root mean square error of prediction (RMSEP) and correlation coefficient (R²). Pre-processing with orthogonal signal correction (OSC) yielded a model which predicted P57 content based on the FT-Raman spectra with a correlation coefficient (R²) value of 0.9986 and an RMSEP of 0.004%. These results demonstrate that FT-Raman spectroscopy holds great potential to rapidly quantify P57 in H. gordonii raw material with high accuracy as an alternative to LC–MS analysis. In addition, the spatial distribution of P57 in a cross-section of an H. gordonii stem sample was demonstrated using FT-Raman mapping showing that P57 is concentrated throughout the cortex which was confirmed with LC–MS.     

An analysis of the effect of lower extremity strength on impact severity during a backward fall.

At least 280 000 hip fractures occur annually in the U.S. at an estimated cost of $9 billion. While over 90 percent of these are caused by falls, only about 2 percent of all falls result in hip fracture. Evidence suggests that the most important determinants of hip fracture risk during a fall are the body's impact velocity and configuration. Accordingly, protective responses for reducing impact velocity and the likelihood for direct impact to the hip, strongly influence fracture risk. One method for reducing the body's impact velocity and kinetic energy during a fall is to absorb energy in the lower extremity muscles during descent, as occurs during sitting and squatting. In the present study, we employed a series of in verted pendulum models to determine: (a) the theoretical effect of this mechanism on impact severity during a backward fall, and (b) the effect on impact severity of age-related declines (or exercise-induced enhancements) in lower extremity strength. Compared to the case of a fall with zero energy absorption in the lower extremity joints, best-case falls (which involved 81 percent activation of ankle and hip muscles, but only 23 percent activation of knees muscles) involved 79 percent attenuation (from 352 J to 74 J) in the body's vertical kinetic energy at impact (KEv), and 48 percent attenuation (from 3.22 to 1.68 m/s) in the downward velocity of the pelvis at impact (v(v)). Among the mechanisms responsible for this were: (1) eccentric contraction of lower extremity muscles during descent, which resulted in up to 150 J of energy absorption; (2) impact with the trunk in an upright configuration, which reduced the change in potential energy associated with the fall by 100 J; and (3) knee extension during the final stage of descent, which "transferred" up to 90 J of impact energy into horizontal (as opposed to vertical) kinetic energy. Declines in joint strength reduced the effectiveness of mechanisms (1) and (3), and thereby increased impact severity However, even with reductions of 80 percent in available torques, KEv was attenuated by 50 percent. This indicates the importance of both technique and strength in reducing impact severity. These results provide motivation for attempts to reduce elderly individuals' risk for fall-related injury through the combination of instruction in safe falling techniques and exercises that enhance lower extremity strength.     

Isotherm and kinetic modelling of Toluidine Blue (TB) removal from aqueous solution using Lemna minor

The aim of this study was to investigate the ability of Lemna minor for Toluidine Blue (TB) removal. Influence of the initial concentration over the removal process was considered. Experimental data have been analyzed using Langmuir, Freundlich, Dubinin–Radushkevich (D–R), and Elovich isotherm models. In addition, several kinetic models, pseudo-first-, pseudo-second-order, intraparticle and film diffusion models were considered. Langmuir and Freundlich isotherm suggested a favorable adsorption of TB by Lemna minor plants. From the D–R the mean free energy was calculated to be 11.18 kJ/mol, which indicates that TB adsorption was characterized by a chemisorption process. Kinetic studies showed that liquid film diffusion plays an important role during the process. Adsorption capacities of up to 26.69 mg/g and a high capacity of adaptation indicated that phytoremediation using Lemna minor could be a valuable alternative for dyes removal from wastewaters.     

Between-day repeatability of lower limb EMG measurement during running and walking

There are minimal data describing the between-day repeatability of EMG measurements during running. Furthermore, there are no data characterising the repeatability of surface EMG measurement from the adductor muscles, during running or walking. The purpose of this study was to report on the consistency of EMG measurement for both running and walking across a comprehensive set of lower limb muscles, including adductor magnus, longus and gracilis. Data were collected from 12 lower limb muscles during overground running and walking on two separate days. The coefficient of multiple correlation (CMC) was used to quantify waveform similarity across the two sessions for signals normalised to either maximal voluntary isometric contraction (MVIC) or mean/peak signal magnitude. For running, the data showed good or excellent repeatability (CMC = 0.87–0.96) for all muscles apart from gracilis and biceps femoris using the MVIC method. Similar levels of repeatability were observed for walking. Importantly, using the peak/mean method as an alternative to the MVIC method, resulted in only marginal improvements in repeatability. The proposed protocol facilitated the collection of repeatable EMG data during running and walking and therefore could be used in future studies investigating muscle patterns during gait.     

Using force sensing insoles to predict kinetic knee symmetry during a stop jump

Knee kinetic asymmetries are present during jump-landings in athletes returning to sport following anterior cruciate ligament (ACL) reconstruction, and are associated with an increased risk for sustaining a second ACL injury. The loadsol® is a wireless load sensing insole that can be used in non-laboratory settings. The purpose of this study was to determine if the loadsol® could be used to predict knee extension moment and power symmetry during a bilateral stop jump task in healthy recreational athletes. Forty-two uninjured recreational athletes completed seven bilateral stop jumps. During each landing, the loadsol® (100 Hz) measured plantar load while 3D ground reaction forces (1920 Hz) and lower extremity kinematics (240 Hz) were collected simultaneously. Peak impact force, loading rate, and impulse were quantified using the loadsol® and peak knee extension moment, average knee extension moment, and total knee work was quantified using the laboratory instrumentation. Limb symmetry indices were quantified for each outcome measure. Multivariate backwards regressions were used to determine if loadsol® symmetry could predict knee kinetic symmetry. Intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to determine the agreement and error between predicted and actual knee kinetic symmetry. Loadsol® impulse and peak impact force symmetry significantly predicted kinetic knee symmetry and explained 42–61% of its variance. There was good agreement (ICCs = 0.742–0.862) between predicted and actual knee kinetic symmetry, and the error in the predicted outcomes range from ±18 to ±43. These results support using the loadsol® to screen for kinetic symmetries during landing in athletes following ACL reconstruction.     

Functional activity characteristics of individuals with shoulder dysfunctions

Shoulder-related dysfunction affects individuals’ ability to function independently and thus decreases quality of life. Functional task assessment is a key concern for a clinician in diagnostic assessment, outcome measurement, and planning of treatment programs. The purpose of this study was to test the reliability of the FASTRAK 3-dimensional (3-D) motion analysis and surface electromyography (sEMG) systems to analyze 3-D shoulder complex movements during functional tasks and compare motion patterns between subjects with and without shoulder dysfunctions (SDs).For the test, sEMG and 3-D motion analysis systems were used to characterize the functional tasks. Twenty-five asymptomatic male subjects and 21 male subjects with right shoulder disorders performed four functional tasks which involved arm reaching and raising activities with their dominant arms. Reliability was estimated by the intraclass correlation coefficient (ICC). Motion pattern was compared between two groups using mixed analysis of variances (ANOVAs). Shoulder complex kinematics and associated muscular activities during functional tasks were reliably quantified (ICC = 0.83–0.99) from the means of three trials. Relative to the group without SDs, the group with SDs showed significant alteration in shoulder complex kinematics (3°–40°) and associated muscular activities (3–10% maximum). Scapular tipping, scapular elevation, upper trapezius muscle function, and serratus anterior muscle function may have implications in the rehabilitation of patients with SDs.     

Characterization of the caprine estrous cycle using enzyme immunoassay for the determination of whole blood progesterone concentration

Eighteen mature female dairy goats were used to determine the feasibility of enzyme immunoassay for the measurement of progesterone in this species. Both quantitative and qualitative enzyme immunoassay kits were used to measure progesterone concentration in unextracted whole blood. Progesterone profiles were similar to those previously reported using either protein-binding or radioimmunoassay as the test. A Pearson's correlation coefficient comparison of our enzyme immunoassay values with radioimmunoassay values gave a correlation coefficient of 0.95. Using the qualitative test, 100% of the samples with high progesterone concentrations had quantitative values greater than 4.00 ng/ml progesterone with a mean of 12.13 ng/ml. Estrus samples had a mean progesterone concentration of 0.70 ng/ml.     

Conjugate momentum estimate using non-linear dynamic model of the sit-to-stand correlates well with accelerometric surface data

The purpose of this study was the development of a non-linear double inverted constrained pendulum model for the analysis of the movement of sit-to-stand (STS) transition. Ten able-bodied subjects perform five trials in their natural speed. Kinematics, kinetics as well as body worn accelerometer data were collected during the STS task using optoelectronic motion capture, force plate and inertial measurement unit, respectively. The conjugate momentum for the whole body which includes linear and angular motion correlates well with the accelerometric surface spanned by the accelerometer data. The partitioning of the conjugate momentum indicates a clear coordination between upper and lower limb after seat-off period. Moreover, the normalization procedure indicates a clear minimal and somehow invariant threshold value of the conjugate momentum to approximately 0.3 (body mass×body length) to perform the sit-to-stand for able-bodied subject. This threshold correlates well with the data obtained from accelerometeric index. The proposed accelerometric index is relevant to assess STS performance and to detect failed STS in clinics and outside a laboratory for patients with reduced mobility.     

Mechanics of a constrained chair-rise

A sit-to-stand task is analyzed by a method which estimates the segmental and whole body center of mass (CoM) kinematics and kinetics using bilateral whole body kinematic data from nine healthy young female subjects. The sit-to-stand, or chair-rise, task is constrained with regard to chair height, pace, initial lower limb position and arm use. The chair-rise maneuver is divided into four phases; (1) the flexion momentum phase; (2) the momentum transfer phase; (3) the vertical extension phase; and (4) the stabilization phase; the first three are examined in detail here. The momentum transfer phase, which immediately follows lift-off from the seat of the chair, is the most dynamic portion of the event, demanding a high degree of coordination. This maneuver is analyzed in order to determine if trunk movement is used only to position the body center of gravity or if the trunk motion generates momentum which is important during the brief but critical period of dynamic equilibrium immediately following lift-off from the chair. Our evidence points to the latter case and indicates that inter-segmental momentum transfer is possible during this period.