Sit-to-Stand Kinetics and Correlates of Performance in Young and Older Males

Effect of initial foot angle (IFA) on kinematics and dynamics of body during sit-to-stand transfer

Sit-to-stand (STS) is considered the most common functional activities in daily life and the basis for other activities. The elderly and patients with lower limb disorders could not complete the STS motion very well due to limb pain and muscle weakness. Physiotherapist find that specific STS transfer strategies can make patients more easily to complete this task. However, few researchers pay attention to the effect of initial foot angle (IFA) on STS motion. Twenty-six healthy subjects were randomly selected to perform STS transfer experiment. The motion characteristic parameters of subjects under 4 different IFAs (nature, 0°, 15°, and 30°) were obtained, including the percentage of duration in each phase, the velocity of joints, rotation angle and angular velocity of joints (shoulder, hip and knee), center of gravity (COG) trajectory. the change of plantar pressure parameters, and dynamic margin of stability. By comparing the motion characteristic parameters obtained under different IFAs and carrying out statistical analysis, the influence of different IFAs on body kinematics and dynamics during STS task was further explored. The kinematic parameters obtained under different IFAs are significantly different. The percentage of duration in each phase of the STS transfer was different with different IFA, the main differences were in phase I and phase II. The phase I of U15 took 24.5% T, while phase I of N, U0 and U30 took about 20% T, and the maximum difference was (U15-U0) 5.4%. The phase II of U15 took the least time, about 30.8% T. When the IFA is nature (N) and 15°(U15), the trajectories of COG are basically in coincidence; when the IFA is 0°(U0) and 30°(U30), the displacement of COG in anterior-posterior direction is larger. The larger the IFA, the smaller the plantar pressure parameter. When the IFA is 15°, the COG is close to the center of limits of stability, which can provide a better stability. This paper summarizes the influence under 4 different experimental conditions of IFAs on STS transfer, so as to provide a starting point and bases for clinicians to develop rehabilitation training protocols and STS motion strategies for patient.

Effect of a Passive Exosuit on Sit-to-Stand Performance in Geriatric Patients Measured by Body-Worn Sensors-A Pilot Study

Standing up from a seated position is a prerequisite for any kind of physical mobility but many older persons have problems with the sit-to-stand (STS) transfer. There are several exosuits available for industrial work, which might be adapted to the needs of older persons to support STS transfers. However, objective measures to quantify and evaluate such systems are needed. The aim of this study was to quantify the possible support of an exosuit during the STS transfer of geriatric patients. Twenty-one geriatric patients with a median age of 82 years (1.-3.Q. 79-84 years) stood up at a normal pace (1) from a chair without using armrests, (2) with using armrests and (3) from a bed with pushing off, each condition with and without wearing an exosuit. Peak angular velocity of the thighs was measured by body-worn sensors. It was higher when standing up with exosuit support from a bed (92.6 (1.-3.Q. 84.3-116.2)°/s versus 79.7 (1.-3.Q. 74.6-98.2)°/s; p = 0.014) and from a chair with armrests (92.9 (1.-3.Q. 78.3-113.0)°/s versus 77.8 (1.-3.Q. 59.3-100.7)°/s; p = 0.089) compared to no support. There was no effect of the exosuit when standing up from a chair without using armrests. In general, it was possible to quantify the support of the exosuit using sensor-measured peak angular velocity. These results suggest that depending on the STS condition, an exosuit can support older persons during the STS transfer.

Assessment of Thigh Angular Velocity by an Activity Monitor to Describe Sit-to-Stand Performance

The assessment of sit-to-stand (STS) performance is highly relevant, especially in older persons, but testing STS performance in the laboratory does not necessarily reflect STS performance in daily life. Therefore, the aim was to validate a wearable sensor-based measure to be used under unsupervised daily life conditions. Since thigh orientation from horizontal to vertical is characteristic for STS movement, peak angular velocity (PAV) of the thigh was chosen as the outcome variable. A total of 20 younger and older healthy persons and geriatric patients (mean age: 55.5 ± 20.8 years; 55% women) with a wide range of STS performance were instructed to stand up from a chair at their usual pace. STS performance was measured by an activity monitor, force plates, and an opto-electronic system. The association between PAV measured by the thigh-worn activity monitor and PAV measured by the opto-electronic system (gold standard) was r = 0.74. The association between PAV measured by the thigh-worn activity monitor and peak power measured by force plate and opto-electronic system was r = 0.76. The Intra-Class Coefficient (ICC) of agreement between the 2 trials was ICC_(A,1) = 0.76. In this sample of persons with a wide range of physical performance, PAV as measured by a thigh-worn acceleration sensor was a valid and reliable measure of STS performance.

Rate of Force Development Is Related to Maximal Force and Sit-to-Stand Performance in Men With Stages 3b and 4 Chronic Kidney Disease

Introduction: The primary aims of the present study were to assess the relationships of early (0–50 ms) and late (100–200 ms) knee extensor rate of force development (RFD) with maximal voluntary force (MVF) and sit-to-stand (STS) performance in participants with chronic kidney disease (CKD) not requiring dialysis.

Methods: Thirteen men with CKD (eGFR = 35.17 ±.5 ml/min per 1.73 m², age = 70.56 ±.4 years) and 12 non-CKD men (REF) (eGFR = 80.31 ± 4.8 ml/min per 1.73 m², age = 70.22 ±.9 years) performed maximal voluntary isometric contractions to determine MVF and RFD of the knee extensors. RFD was measured at time intervals 0–50 ms (RFD₀₋₅₀) and 100–200 ms (RFD_100−200). STS was measured as the time to complete five repetitions. Measures of rectus femoris grayscale (RF GSL) and muscle thickness (RF MT) were obtained via ultrasonography in the CKD group only. Standardized mean differences (SMD) were used to examine differences between groups. Bivariate relationships were assessed by Pearson's product moment correlation.

Results: Knee extensor MVF adjusted for body weight (CKD=17.14 ±.1 N·kg^0.67, REF=21.55 ±.3 N·kg^0.67, SMD = 0.79) and STS time (CKD = 15.93 ±.4 s, REF = 12.23 ±.7 s, SMD = 1.03) were lower in the CKD group than the REF group. Absolute RFD_100−200 was significantly directly related to adjusted MVF in CKD (r = 0.56, p = 0.049) and REF (r = 0.70, p = 0.012), respectively. STS time was significantly inversely related to absolute (r = −0.75, p = 0.008) and relative RFD₀₋₅₀ (r = −0.65, p = 0.030) in CKD but not REF (r = 0.08, p = 0.797; r = 0.004, p = 0.991). Significant inverse relationships between RF GSL adjusted for adipose tissue thickness and absolute RFD_100−200 (r =−0.59, p = 0.042) in CKD were observed.

Conclusion: The results of the current study highlight the declines in strength and physical function that occur in older men with CKD stages 3b and 4 not requiring dialysis. Moreover, early RFD was associated with STS time in CKD while late RFD was associated MVF in both CKD and REF.

Clinical Trial Registration: ClinicalTrials.gov, identifier: NCT03160326 and NCT02277236.