Use of force-velocity relationship to estimate the one-repetition maximum leg press exercise among young females.

[Purpose] This study aimed to determine the concurrent validity of using force at a velocity of 0 m/s when estimating the one-repetition maximum leg press and develop and assess the accuracy of an equation to estimate the one-repetition maximum value. [Participants and Methods] Ten untrained healthy females participated. We directly measured the one-repetition maximum during the one leg press exercise and developed the individual force-velocity relationship using the trial with the highest mean propulsive velocity at 20% and 70% of the one-repetition maximum. We then used the force at a velocity of 0 m/s to estimate the measured one-repetition maximum. [Results] The force at a velocity of 0 m/s was strongly correlated with the measured one-repetition maximum. A simple linear regression analysis revealed a significant estimated regression equation. The multiple coefficient of the determination of this equation was 0.77, while the standard error of the estimate of the equation was 12.5 kg. [Conclusion] The estimation method based on the force-velocity relationship was highly valid and accurate at estimating the one-repetition maximum for the one leg press exercise. The method provides valuable information to instruct untrained participants at the start of resistance training programs.

Relative and absolute reliability of gait variables obtained from gait analysis with trunk acceleration in community-dwelling individuals with chronic stroke: a pilot study.

[Purpose] This pilot study aimed to investigate the relative and absolute reliability of variables obtained from an acceleration-based gait analysis conducted at comfortable and maximal gait speeds in individuals with chronic stroke. [Participants and Methods] This study included 25 community-dwelling individuals with chronic stroke. The participants wore triaxial accelerometers, while an observed walking trial was performed at comfortable and maximal speeds on two separate days 1 week apart. Relative reliability was evaluated using the intraclass correlation coefficient, and absolute reliability was evaluated using the Bland-Altman analysis, standard error of measurement, and minimal detectable change. [Results] The intraclass correlation coefficient of gait varied according to the acceleration-based gait analysis, ranging from 0.70 to 0.99. The Bland-Altman analysis revealed no systematic bias in both comfortable and maximal gait speed conditions. Most of the minimal detectable changes were smaller at maximal gait speed than at comfortable gait speed. [Conclusion] Acceleration-based gait analysis is a reliable method, particularly in maximal gait speed conditions. It may be used to assess the effect of rehabilitation interventions in individuals with chronic stroke.

Blood pressure reduction cut-points for orthostatic hypotension in stroke survivors using a sit-up test: a multicentre cross-sectional study.

OBJECTIVE: The sit-up test is used to assess orthostatic hypotension in stroke survivors who cannot stand independently without using a tilt table. However, no study has identified the optimal cut-points for orthostatic hypotension using the test. Therefore, this study aimed to examine the decrease in SBP and DBP during the sit-up test to detect orthostatic hypotension in individuals with stroke. METHODS: Thirty-eight individuals with stroke, recruited from three convalescent rehabilitation hospitals, underwent the sit-up and head-up tilt tests. Systolic and diastolic orthostatic hypotension was defined as a decrease of at least 20 and 10 mmHg in the SBP and DBP, respectively, during the head-up tilt test. The receiver operator characteristic curve with the Youden Index was used to identify the optimal cut-points. RESULTS: Eight and three participants showed systolic and diastolic orthostatic hypotension, respectively. The optimal cut-points for orthostatic hypotension using the sit-up test were a decrease of 10 mmHg in SBP [sensitivity = 87.5% (95% confidence interval: 47.4-99.7), specificity = 96.7% (82.8-99.9)] and 5 mmHg in DBP [sensitivity = 100.0% (29.2-100.0), specificity = 88.6% (73.3-96.8)]. CONCLUSION: Compared with the conventional cut-points, smaller cut-points of a decrease in SBP and DBP may be better to identify orthostatic hypotension in individuals with stroke using the sit-up test. The findings of this study may provide valuable information for the clinical application of the sit-up test.

Comparisons of heart rate variability responses to head-up tilt with and without abdominal and lower-extremity compression in healthy young individuals: a randomized crossover study.

Introduction: Abdominal and lower-extremity compression techniques can help reduce orthostatic heart rate increases. However, the effects of body compression on the cardiac autonomic systems, which control heart rate, remain unclear. The primary objective of this study was to compare heart rate variability, a reflection of cardiac autonomic regulation, during a head-up tilt test with and without abdominal and lower-extremity compression in healthy young individuals. The secondary objective was to conduct a subgroup analysis, considering participant sex, and compare heart rate and heart rate variability responses to head-up tilt with and without compression therapy. Methods: In a randomized crossover design, 39 healthy volunteers (20 females, aged 20.9 ± 1.2 years) underwent two head-up tilt tests with and without abdominal and lower-extremity compression. Heart rate and heart rate variability parameters were measured during the head-up tilt tests, including the Stress Index, root mean square of successive differences between adjacent R-R intervals, low- and high-frequency components, and low-to-high frequency ratio. Results: Abdominal and lower-extremity compression reduced the orthostatic increase in heart rate (p < 0.001). The tilt-induced changes in heart rate variability parameters, except for the low-frequency component, were smaller in the compression condition than in the no-compression condition (p < 0.001). These results were consistent regardless of sex. Additionally, multiple regression analysis with potentially confounding variables revealed that the compression-induced reduction in Stress Index during the head-up tilt position was a significant independent variable for the compression-induced reduction in heart rate in the head-up tilt position (coefficient = 0.411, p = 0.025). Conclusion: Comparative analyses revealed that abdominal and lower-extremity compression has a notable impact on the compensatory sympathetic activation and vagal withdrawal typically observed during orthostasis, resulting in a reduction of the increase in heart rate. Furthermore, this decrease in heart rate was primarily attributed to the attenuation of cardiac sympathetic activity associated with compression. Our findings could contribute to the appropriate application of compression therapy for preventing orthostatic tachycardia. This study is registered with UMIN000045179.

Bioelectrical impedance analysis to estimate one-repetition maximum measurement of muscle strength for leg press in healthy young adults.

Resistance training (RT) progress is determined by an individual's muscle strength, measured by one-repetition maximum (1RM). However, this evaluation is time-consuming and has some safety concerns. Bioelectrical impedance analysis (BIA) is a valid and easy-to-use method to assess skeletal muscle mass (SMM). Although BIA measurements are often correlated with muscle strength, few studies of 1RM for RT and BIA measurements are available. This observational study examined the relationship between 1RM and BIA measurements and developed BIA-based prediction models for 1RM. Thirty-five healthy young Japanese adults were included. SMM and the skeletal muscle mass index (SMI) were measured using the BIA device. In addition, dominant-leg 1RM was measured using a unilateral leg-press (LP) machine. The correlations between BIA measurements and 1RM were calculated, and simple regression analyses were performed to predict 1RM from the BIA variables. The results showed significant correlations between 1RM and dominant-leg SMM (R = 0.845, P = 0.0001) and SMI (R = 0.910, P = 0.0001). The prediction models for 1RM for LP derived from SMM of the dominant leg and SMI were Y = 8.21x + 8.77 (P = 0.0001), R2 = 0.73, and Y = 15.53x - 36.33 (P = 0.0001), R2 = 0.83, respectively. Our results indicated that BIA-based SMI might be used to predict 1RM for LP accurately.

Comparison of the sit-up test and head-up tilt test for assessing blood pressure and hemodynamic responses in healthy young individuals.

OBJECTIVE: The sit-up test is used to assess orthostatic hypotension, without the use of a tilt table, in populations who are unable to stand. The primary objective of this study was to determine the differences in blood pressure and hemodynamic responses between the sit-up and head-up tilt tests. The secondary objective was to determine the hemodynamic responses related to changes in blood pressure during each test. METHODS: Nineteen healthy volunteers (nine males, aged 24.3 ± 2.4 years) underwent the sit-up and head-up tilt tests. Systolic and diastolic blood pressure, heart rate, stroke volume, cardiac output, and total peripheral resistance were measured. RESULTS: The increase in systolic blood pressure (15 ± 9 vs. 8 ± 8 mmHg) was greater, while the increase in heart rate (8 ± 5 vs. 12 ± 8 bpm) and reduction in stroke volume (-17 ± 10 vs. -21 ± 10 ml) were smaller during the sit-up test than during the head-up tilt test (P < 0.05). Additionally, the increases in blood pressure variables were significantly associated with the increase in total peripheral resistance (P < 0.05), but not with changes in other hemodynamic variables in both tests. CONCLUSION: Although the magnitudes of changes in systolic blood pressure, heart rate, and stroke volume differed between the tests, the hemodynamic variable related to changes in blood pressure was the same for both tests. These results may contribute to the clinical application of the sit-up test for identifying the presence and hemodynamic mechanisms of orthostatic hypotension.

Preexisting brain lesions in patients with post stroke pusher behavior and their association with the recovery period: A one year retrospective cohort study in a rehabilitation setting.

The presence of preexisting brain lesions due to previous stroke and cerebral small vessel disease has been reported to influence stroke related disability or rehabilitation outcomes. However, there is no data about the impact of such lesions on the recovery period after pusher behavior (PB). This retrospective cohort study aimed to determine the influence of preexisting brain lesions on PB recovery time. Nineteen patients who were suffering from PB were included in the study. The presence of preexisting brain lesions, including previous stroke, silent brain infarcts, microbleed, white matter hyperintensity, and enlarged perivascular spaces were assessed using medical history reports, radiological reports, and magnetic resonance imaging data. The lesion score, ranging from 0 to 5, was calculated based on each preexisting brain lesion. The time to recovery from PB was assessed using the Scale for Contraversive Pushing. Based on the median value of the lesion score, we divided patients into those with a lesion score < 2 and those with a lesion score ≥ 2. A Kaplan Meier survival analysis was performed between these two groups. A multivariable Cox proportional hazards analysis was also performed using the side with hemiparesis and the score of preexisting brain lesions as covariates to determine the hazard ratio. The results showed that the group with a lesion score ≥ 2 had significantly delayed recovery from PB and the hazard ratio of preexisting brain lesions score was 0.458 (95% confidence interval: 0.221, 0.949), while the side of hemiparesis was not identified a significant covariate. Our results indicated that patients with PB having higher score of preexisting brain abnormalities might require a longer time to recover, and this might be useful in planning inpatient rehabilitation and treatment goals for patients with PB.

The relationship between energy expenditure and physical functions in patients hospitalised for stroke.

We assessed the relationship between energy expenditure (EE) and Functional Independence Measure motor items (FIM-M) score, Berg Balance Scale (BBS) score, and comfortable walking speed (CWS) in patients hospitalised for stroke. The total EE per day (TEE), EE during rehabilitation (REE), and EE during activities other than rehabilitation (OEE) were measured using a single-axis acceleration sensor in 36 patients hospitalised for the first stroke episode. In addition, the relationships between each type of EE and FIM-M, BBS, and CWS were investigated. In these patients (mean age 66.2 ± 10.6 years), the median values of TEE, REE, and OEE were 41.8 kcal, 18.5 kcal, and 16.6 kcal, respectively. Correlations were observed between each EE type and all physical function indices. Following the stratification of patients into two groups (high and low) based on the level of physical function, a significant correlation between EE type and physical function was observed only in the low BBS group. EE was correlated with overall physical function indices, but the trend differed depending on physical ability. When patients were stratified based on ability, there were several groups with no significant correlation. Therefore, several patients were unable to achieve an appropriate EE for their level of physical function.

A Single Bout of Constant-Load Exercise Test for Estimating the Time Constant of Oxygen Uptake Kinetics in Individuals With Stroke.

OBJECTIVE: To examine the relationship between the time constant of oxygen uptake kinetics during the onset of exercise (τVO2) estimated from a single exercise bout and that obtained from three averaged exercise bouts in individuals with stroke. METHODS: Twenty participants with stroke performed three bouts of a constant-load pedaling exercise at approximately 80% of the workload corresponding to the ventilatory threshold to estimate τVO2. The VO2 data from the first trial of three bouts were used to estimate τVO2 for a single bout. Additionally, data collected from three bouts were ensemble-averaged to obtain τVO2 for three averaged bouts as the criterion. RESULTS: There was a very high correlation between τVO2 for a single bout (34.8±14.0 seconds) and τVO2 for three averaged bouts (38.5±13.4 seconds) (r=0.926, p<0.001). However, τVO2 for a single bout was smaller than that for three averaged bouts (p=0.006). CONCLUSION: τVO2 for a single bout could reflect the relative difference in τVO2 for three averaged bouts among individuals with stroke. However, it should be noted that τVO2 for a single bout may be underestimated compared to τVO2 for three averaged bouts.

Cardiorespiratory responses to exercise related to post-stroke fatigue severity.

Physical deconditioning after stroke may induce post-stroke fatigue. However, research on this association is limited. Our primary objective was to investigate the associations of post-stroke fatigue severity with oxygen uptake ([Formula: see text]O2) at peak exercise and the time constant of [Formula: see text]O2 kinetics (τ[Formula: see text]O2) at exercise onset. The secondary objective was to examine the associations between fatigue and cardiorespiratory variables potentially affecting [Formula: see text]O2 during exercise. Twenty-three inpatients from a subacute rehabilitation ward were enrolled in this study. The median (interquartile range) Fatigue Severity Scale (FSS) score, as a measure of fatigue, was 32 (range 27-42) points. The FSS score was not associated with [Formula: see text]O2 at peak exercise during a symptom-limited graded exercise test (rho = - 0.264; p = 0.224), whereas it was significantly associated with τ[Formula: see text]O2 during a submaximal constant-load exercise test (rho = 0.530; p = 0.009). A higher FSS score also significantly correlated with a longer time constant of cardiac output (CO) kinetics (rho = 0.476; p = 0.022). Our findings suggest that severe post-stroke fatigue is associated with delayed increases in [Formula: see text]O2 and CO at the onset of exercise. Our findings can contribute to the development of an appropriate rehabilitation programme for individuals with post-stroke fatigue.

Motivational Strategies for Stroke Rehabilitation: A Delphi Study.

OBJECTIVES: The primary objective was to provide a list of effective motivational strategies based on consensus among rehabilitation experts, generated using the Delphi technique. The secondary objective was to identify the types of information that are important when selecting motivational strategies. DESIGN: Delphi study. SETTING: On-site survey at academic conferences and web-based survey. PARTICIPANTS: Rehabilitation experts (N=198) including physicians, physical therapists, occupational therapists, and speech-language-hearing therapists who had worked in stroke rehabilitation for at least 5 years. INTERVENTION: Not applicable. MAIN OUTCOME MEASURES: Panelists were asked to rate the effectiveness of motivational strategies and to rate the importance of different types of information using a 5-point Likert scale. Consensus was defined as having been reached for items with an interquartile range of 1 or less. RESULTS: A total of 116 experts (58.6%) completed the third round of the Delphi survey. Consensus was reached on all of the 26 presented strategies. Seven strategies, such as control of task difficulty and goal setting, were considered to be very effective in increasing patient motivation. In addition, all 11 of the presented types of information regarding patient health status, environmental factors, and personal factors were deemed very important or important in determining which motivational strategies to use. CONCLUSIONS: We generated a list of effective motivational strategies for stroke rehabilitation based on expert consensus. Our results suggest that experts consider a comprehensive range of patient information when choosing motivational strategies. These findings represent a group of consensus-based recommendations for increasing patient adherence to stroke rehabilitation programs, which may be beneficial to many medical professionals working in stroke rehabilitation.

Correlation between radiographic sagittal alignment, range of motion, muscle strength, and quality of life in adults with spinal deformities.

[Purpose] The aims of this study were to examine the relationship between range of motion/muscle strength of the spine and lower limbs with 1) radiographic sagittal alignment and 2) quality of life of participants with spinal deformities to adequately target the appropriate factors for effective treatment. [Participants and Methods] This study used an observational cross-sectional correlational design. Participants with spinal deformities and low back pain were recruited for the study. The dependent variables were range of motion/muscle strength of the spine and lower limbs, sagittal alignment, and quality of life. [Results] Regarding alignment, significant correlations were found between hip extension range of motion and sagittal vertebral axis; between occiput-to-wall distance and thoracolumbar kyphosis; and between back extensor endurance and pelvic tilt and pelvic incidence-lumbar lordosis mismatch, also known as the calculated (pelvic incidence) minus (lumbar lordosis) value. With regards to quality of life, significant correlations were found between pain-related disorders and lumbar spine range of motion, and between gait disturbance and knee and hip extension ranges of motion. [Conclusion] Our findings suggest that these factors should be targeted for assessment and treatment of adults with spinal deformities.

Cardiorespiratory factors related to the increase in oxygen consumption during exercise in individuals with stroke.

BACKGROUND: Understanding the cardiorespiratory factors related to the increase in oxygen consumption ([Formula: see text]) during exercise is essential for improving cardiorespiratory fitness in individuals with stroke. However, cardiorespiratory factors related to the increase in [Formula: see text] during exercise in these individuals have not been examined using multivariate analysis. This study aimed to identify cardiorespiratory factors related to the increase in [Formula: see text] during a graded exercise in terms of respiratory function, cardiac function, and the ability of skeletal muscles to extract oxygen. METHODS: Eighteen individuals with stroke (aged 60.1 ± 9.4 years, 67.1 ± 30.8 days poststroke) underwent a graded exercise test for the assessment of cardiorespiratory response to exercise. The increases in [Formula: see text] from rest to first threshold and that from rest to peak exercise were measured as a dependent variable. The increases in respiratory rate, tidal volume, minute ventilation, heart rate, stroke volume, cardiac output, and arterial-venous oxygen difference from rest to first threshold and those from rest to peak exercise were measured as the independent variables. RESULTS: From rest to first threshold, the increases in arterial-venous oxygen difference (ß = 0.711) and cardiac output (ß = 0.572) were significant independent variables for the increase in [Formula: see text] (adjusted R2 = 0.877 p < 0.001). Similarly, from rest to peak exercise, the increases in arterial-venous oxygen difference (ß = 0.665) and cardiac output (ß = 0.636) were significant factors related to the increase in [Formula: see text] (adjusted R2 = 0.923, p < 0.001). CONCLUSION: Our results suggest that the ability of skeletal muscle to extract oxygen is a major cardiorespiratory factor related to the increase in [Formula: see text] during exercise testing in individuals with stroke. For improved cardiorespiratory fitness in individuals with stroke, the amount of functional muscle mass during exercise may need to be increased.

Intertrial Rest for Maximum Grip and Key Pinch Strength in Japanese Young Adults.

OBJECTIVE: This study investigated the most appropriate intertrial rest period for maximum grip and key pinch strength measurements involving three trials. METHOD: The study included 40 male and 40 female participants. Using a repeated-measures design, six intertrial rest periods-15 s, 30 s, 60 s, 90 s, 120 s, and 150 s-were investigated, one per day on 6 different days. RESULTS: A repeated-measures analysis of variance or Friedman test found significant decreases in grip and key pinch strength over the three trials in all test conditions. However, for both hands, only small differences were observed in test conditions (≥90 s, male grip; ≥60 s, female grip; male and female key pinch; effect sizes of <0.5). CONCLUSION: If a rest of ≥150 s is not possible, 90 s of rest between trials for grip strength and 60 s of rest between trials for key pinch strength can be considered.

Validity of maximal isometric knee extension strength measurements obtained via belt-stabilized hand-held dynamometry in healthy adults.

[Purpose] To determine the validity of knee extension muscle strength measurements using belt-stabilized hand-held dynamometry with and without body stabilization compared with the gold standard isokinetic dynamometry in healthy adults. [Subjects and Methods] Twenty-nine healthy adults (mean age, 21.3 years) were included. Study parameters involved right side measurements of maximal isometric knee extension strength obtained using belt-stabilized hand-held dynamometry with and without body stabilization and the gold standard. Measurements were performed in all subjects. [Results] A moderate correlation and fixed bias were found between measurements obtained using belt-stabilized hand-held dynamometry with body stabilization and the gold standard. No significant correlation and proportional bias were found between measurements obtained using belt-stabilized hand-held dynamometry without body stabilization and the gold standard. The strength identified using belt-stabilized hand-held dynamometry with body stabilization may not be commensurate with the maximum strength individuals can generate; however, it reflects such strength. In contrast, the strength identified using belt-stabilized hand-held dynamometry without body stabilization does not reflect the maximum strength. Therefore, a chair should be used to stabilize the body when performing measurements of maximal isometric knee extension strength using belt-stabilized hand-held dynamometry in healthy adults. [Conclusion] Belt-stabilized hand-held dynamometry with body stabilization is more convenient than the gold standard in clinical settings.

Validity of gait asymmetry estimation by using an accelerometer in individuals with hemiparetic stroke.

[Purpose] The purpose of this study was to evaluate the validity of estimating step time and length asymmetries, using an accelerometer against force plate measurements in individuals with hemiparetic stroke. [Subjects and Methods] Twenty-four individuals who previously had experienced a stroke were asked to walk without using a cane or manual assistance on a 16-m walkway. Step time and length were measured using force plates, which is the gold standard for assessing gait asymmetry. In addition to ground reaction forces, trunk acceleration was simultaneously measured using an accelerometer. To estimate step time asymmetry using accelerometer data, the time intervals between forward acceleration peaks for each leg were calculated. To estimate step length asymmetry using accelerometer data, the integration of the positive vertical accelerations following initial contact of each leg was calculated. Asymmetry was considered the affected side value divided by the unaffected side value. [Results] Significant correlations were found between the accelerometer and the force plates for step time and length asymmetries (rho=0.83 and rho=0.64, respectively). [Conclusion] An accelerometer might be useful for assessing step time and length asymmetries in individuals with hemiparetic stroke, although improvements are needed for estimating the accuracy of step length asymmetry.

Unilateral Arm Crank Exercise Test for Assessing Cardiorespiratory Fitness in Individuals with Hemiparetic Stroke.

Cardiorespiratory fitness assessment with leg cycle exercise testing may be influenced by motor impairments in the paretic lower extremity. Hence, this study examined the usefulness of a unilateral arm crank exercise test to assess cardiorespiratory fitness in individuals with stroke, including sixteen individuals with hemiparetic stroke (mean ± SD age, 56.4 ± 7.5 years) and 12 age- and sex-matched healthy controls. Participants performed the unilateral arm crank and leg cycle exercise tests to measure oxygen consumption ([Formula: see text]O2) and heart rate at peak exercise. The [Formula: see text]O2 at peak exercise during the unilateral arm crank exercise test was significantly lower in the stroke group than in the control group (p < 0.001). In the stroke group, the heart rate at peak exercise during the unilateral arm crank exercise test did not significantly correlate with the Brunnstrom recovery stages of the lower extremity (p = 0.137), whereas there was a significant correlation during the leg cycle exercise test (rho = 0.775, p < 0.001). The unilateral arm crank exercise test can detect the deterioration of cardiorespiratory fitness independently of lower extremity motor impairment severity in individuals with hemiparetic stroke. This study is registered with UMIN000014733.

A multicenter trial of a footdrop stimulator controlled by a tilt sensor.

OBJECTIVES: To test the efficacy and acceptance of a footdrop stimulator controlled by a tilt sensor. METHODS: A nonrandomized, test-retest study of 26 subjects with footdrop of more than 1 year's duration, resulting from various central nervous system disorders, was performed in 4 centers for at least 3 months. Speed of walking in a straight line, speed around a figure of 8, and physiological cost index (PCI) were measured with and without the device. Hours/day and steps/day using the device were recorded. RESULTS: All but 2 subjects used the tilt sensor at home, rather than a foot switch. Walking speed increased by 15% after 3 months (n = 26; P < 0.01), 32% after 6 months (n = 16; P < 0.01), and 47% after 12 months (n = 8; P < 0.05), while PCI decreased. The number of steps taken per day of use increased significantly over time, and increased speed was directly correlated with usage. Walking speed also increased with the stimulator off, but to a lesser extent, indicating a training effect. Subject feedback from a questionnaire indicated satisfaction with the stimulator. CONCLUSIONS: Both efficacy and acceptance of the stimulator were good in a population of subjects with chronic footdrop.