Leg Exercise Research Articles

Lower body blood flow restriction training may induce remote muscle strength adaptations in an active unrestricted arm.

We examined the concurrent characteristics of the remote development of strength and cross-sectional area (CSA) of upper body skeletal muscle in response to lower body resistance training performed with an applied blood flow restriction (BFR). Males allocated to an experimental BFR group (EXP; n = 12) or a non-BFR control group (CON; n = 12) completed 7-weeks of resistance training comprising three sets of unilateral bicep curls [50% 1-repetition maximum (1-RM)], then four sets of bilateral knee extension and flexion exercises (30% 1-RM). EXP performed leg exercises with an applied BFR (60% limb occlusion pressure). 1-RM strength was measured using bilateral leg exercises and unilateral bicep curls in both trained and untrained arms. Muscle CSA was measured via peripheral quantitative computed tomography in the dominant leg and both arms. 1-RM in the trained arm increased more in EXP (2.5 ± 0.4kg; mean ± SEM) than the contralateral untrained arm (0.8 ± 0.4kg), and the trained arm of CON (0.6 ± 0.3kg, P < 0.05). The increase in knee extension 1-RM was twofold that of CON (P < 0.01). Knee flexion 1-RM, leg CSA, and trained arm CSA increased similarly between groups (P > 0.05), while untrained arm CSA did not change (P > 0.05). Lower limb BFR training increased trained arm strength more than the contralateral untrained arm, and the trained arm of controls. However, there was no additional effect on muscle CSA. These findings support evidence for a BFR training-derived remote strength transfer that may be relevant to populations with localised movement disorders.

Effects of \u03b2-alanine supplementation during a 5-week strength training program: a randomized, controlled study

Backgroundβ-Alanine (BA) is a non-essential amino acid that has been shown to enhance exercise performance. The purpose of this investigation was to determine if BA supplementation improved the adaptive response to five weeks of a resistance training program.MethodsThirty healthy, strength-trained individuals were randomly assigned to the experimental groups placebo (PLA) or BA. Over 5 weeks of strength training, subjects in BA took 6.4 g/day of BA as 8 × 800 mg doses each at least 1.5 h apart. The training program consisted of 3 sessions per week in which three different leg exercises were conducted as a circuit (back squat, barbell step ups and loaded jumping lunges). The program started with 3 sets of 40 s of work per exercise and rest periods between sets of 120 s in the first week. This training volume was then gradually built up to 5 sets of 20 s work/60 s rest in the fifth week. The work load during the program was set by one of the authors according to the individual’s perceived effort the previous week. The variables measured were average velocity, peak velocity, average power, peak power, and load in kg in a back squat, incremental load, one-repetition maximum (1RM) test. In addition, during the rest period, jump ability (jump height and power) was assessed on a force platform. To compare data, a general linear model with repeated measures two-way analysis of variance was used.ResultsSignificantly greater training improvements were observed in the BA group versus PLA group (p = 0.045) in the variables average power at 1RM (BA: 42.65%, 95% CI, 432.33, 522.52 VS. PLA: 21.07%, 95% CI, 384.77, 482.19) and average power at maximum power output (p = 0.037) (BA: 20.17%, 95% CI, 637.82, 751.90 VS. PLA; 10.74%, 95% CI, 628.31, 751.53). The pre- to post training average power gain produced at 1RM in BA could be explained by a greater maximal strength gain, or load lifted at 1RM (p = 0.014) (24 kg, 95% CI, 19.45, 28.41 VS. 16 kg, 95% CI, 10.58, 20.25) and in the number of sets executed (p = 0.025) in the incremental load test (BA: 2.79 sets, 95% CI, 2.08, 3.49 VS. PLA: 1.58 sets, 95% CI, 0.82, 2.34).Conclusionsβ-Alanine supplementation was effective at increasing power output when lifting loads equivalent to the individual’s maximal strength or when working at maximum power output. The improvement observed at 1RM was explained by a greater load lifted, or strength gain, in response to training in the participants who took this supplement.

Imatinib-Induced Congestive Heart Failure: A Case Report

Imatinib has been approved by the FDA as an oral drug for the treatment of Chronic Myeloid Leukemia (CML), gastrointestinal stromal tumors (GISTs) and hyper eosinophilic syndrome. Although imatinib is well tolerated, the incidence of edema and dyspnea are reported to be as high as 66 and 16%, respectively. Imatinib-induced cardiotoxicity is a very uncommon adverse event <1%. A 53-year-old male with history of Chronic Myeloid Leukemia (CML) on Imatinib for the past 5 years. He presented with symptoms of exertional dyspnea, poor exercise performance, fatigue, and leg swellings. Chest X-ray revealed cardiomegaly, and pulmonary edema. Electrocardiogram showed normal sinus rhythm, no ischemic changes. Cardiac enzymes were normal. 2D Echocardiogram showed ejection fraction EF of 35%, normal pulmonary systolic pressure, no wall motion abnormality, with normal valvular function. In our case report, we discuss the association between Imatinib use and congestive heart failure, which may need discontinuing the medication and prompt treatment of congestive heart failure.

Comparable neutrophil responses for arm and intensity-matched leg exercise

Comparable neutrophil responses for arm and intensity-matched leg exercise

Effectiveness of intradialytic leg exercise on fatigue and activities of daily living

Effectiveness of intradialytic leg exercise on fatigue and activities of daily living

The Effects of Mental Practice about Leg Exercise Muscle Activities of the Rectus Femoris

The Effects of Mental Practice about Leg Exercise Muscle Activities of the Rectus Femoris

Upaya Penderita Kusta dalam Mencegah Peningkatan Derajat Kecacatan

Kusta adalah penyakit kronik yang terutama menyerang kulit dan saraf tepi serta mengakibatkan ulserasi mutilasi dan deformitassehingga dapat menimbulkan masalah sosial, psikologis, dan ekonomis.. Tujuan penelitian ini mengetahui upaya penderita kusta dalam mencegah peningkatan derajat kecacatan. Metode penelitian ini adalah deskriptif dengan populasi seluruh penderita kusta yang mengikuti Kelompok Perawatan Diri (KPD) di Puskesmas Sutojayan dan Ponggok kabupaten Blitar. Jumlah sampel sebanyak 26 orang diambil dengan teknik sampling jenuh. Pengumpulan data dilakukan dengan kuesioner dan observasi. Hasil penelitian menunjukkan bahwa upaya yang dilakukan penderita kusta dalam mencegah peningkatan derajat kecacatan kusta meliputi 42.3% kategori baik, 50% kategori cukup, dan sisanya 7.7% dalam kategori kurang. Upaya pencegahan kecacatan akibat kusta yang kurang dilakukan adalah senam kaki maupun jari tangan untuk mencegah kekakuan pada bagian tersebut. Rekomendasi penelitian ini diharapkan peran Puskesmas dan tenaga kesehatan untuk meningkatkan dukungan dan motivasi kepada penderita kusta dalam melakukan upaya pencegahan derajat kecacatannya.

Kinesiophobia is associated with pain intensity but not pain sensitivity before and after exercise: an explorative analysis

ObjectiveTo compare clinical pain intensity, exercise performance, pain sensitivity and the effect of aerobic and isometric exercise on local and remote pressure pain thresholds (PPTs) in patients with chronic musculoskeletal pain with high and low levels of kinesiophobia. DesignAn experimental pre–post within-subject study. SettingAn exercise laboratory in a multidisciplinary pain clinic. ParticipantsFifty-four patients with chronic musculoskeletal pain. InterventionsAcute aerobic and isometric leg exercises. Main outcome measuresClinical pain intensity (numerical rating scale, range 0 to 10), Tampa Scale of Kinesiophobia, aerobic and isometric exercise performances (intensity and maximal voluntary contraction), and PPTs at local and remote body areas before and after exercise conditions. ResultsPatients with a high degree of kinesiophobia demonstrated increased pain intensity compared with patients with a low degree of kinesiophobia [high degree of kinesiophobia: 7.3 (1.6) on NRS; low degree of kinesiophobia: 6.3 (1.6) on NRS; mean difference 1.0 (95% confidence interval 0.08 to 1.9) on NRS]. Aerobic and isometric exercises increased PPTs, but no significant group differences were found in PPTs before and after exercise. ConclusionsClinical pain intensity was significantly higher in patients with a high degree of kinesiophobia compared with patients with a low degree of kinesiophobia. Despite a difference in isometric exercise performance, the hypoalgesic responses after cycling and isometric knee exercise were comparable between patients with high and low degrees of kinesiophobia. If replicated in larger studies, these findings indicate that although kinesiophobic beliefs influence pain intensity, they do not significantly influence PPTs and exercise-induced hypoalgesia in patients with chronic musculoskeletal pain.

Brachial artery blood flow dynamics during sinusoidal leg cycling exercise in humans

To explore the control of the peripheral circulation of a nonworking upper limb during leg cycling exercise, blood flow (BF) dynamics in the brachial artery (BA) were determined using a sinusoidal work rate (WR) exercise. Ten healthy subjects performed upright leg cycling exercise at a constant WR for 30 min, followed by 16 min of sinusoidal WR consisting of 4‐min periods of WR fluctuating between a minimum output of 20 W and a maximum output corresponding to ventilatory threshold (VT). Throughout the protocol, pulmonary gas exchange, heart rate (HR), mean arterial blood pressure (MAP), blood velocity (BV), and cross‐sectional area of the BA, forearm skin BF (SBF), and sweating rate (SR) were measured. Each variable was fitted to a sinusoidal model with phase shift (θ) and amplitude (A). Nearly all variables closely fit a sinusoidal model. Variables relating to oxygen transport, such as VO2 and HR, followed the sinusoidal WR pattern with certain delays (θ: VO2; 51.4 ± 4.0°, HR; 41.8 ± 5.4°, mean ± SD). Conversely, BF response in the BA was approximately in antiphase (175.1 ± 28.9°) with a relatively large A, whereas the phase of forearm SBF was dissimilar (65.8 ± 35.9°). Thus, the change of BF through a conduit artery to the nonworking upper limb appears to be the reverse when WR fluctuates during sinusoidal leg exercise, and it appears unlikely that this could be ascribed exclusively to altering the downstream circulation to forearm skin.

O33-5 - A case of Adriamycin Cardiomyopathy with Stress Induced Worsening of Mitral Regurgitation -Possible Underlying Mechanism Based on the Circulatory Equilibrium-

A case of adriamycin cardiomyopathy with repeated worsening of heart failure (HF). Rest TTE showed LVDd/s and LVEF were 69/58 mm and 27% with moderate functional mitral regurgitation (MR). Exercise stress induced marked worsening of MR. Simple leg exercise increased PCWP (29 to 44 mmHg), RAP (4 to 10 mmHg) and CI (2.12 to 2.74 L/min/m2). We considered exercise induced worsening of MR is one of the major mechanisms of repeated worsening of HF and performed mitral annuloplasty. After surgery, exercise stress increased RAP (4 to 13 mmHg), PCWP (15 to 30 mmHg) and CI (2.18 to 2.68 L/min/m2). Because the intensities of the exercise were different, we standardized them by the stressed blood volume (SBV). We estimated the SBV using the equation of venous return curve previously reported (Uemura K et al, AJP 2004). Exercise increased SBV from 31.5 to 55.8 ml/kg before surgery and from 25.7 to 57.3 ml/kg after surgery. ΔPWCP/ΔSBV decreased from 0.62 to 0.48 mmHg/(ml/kg) and ΔRAP/ΔSBV increased from 0.25 to 0.29 mmHg/(ml/kg). This indicates that the presence of stress induced worsening of MR contribute to make PCWP sensitive to the change of SBV while little change in the RAP sensitivity. Mitral surgery improves not only static pump function but also dynamic response for stress induced changes in hemodynamics and may prevent flush pulmonary edema.

A novel exercise device for venous thromboembolism prophylaxis improves venous flow in bed versus ankle movement exercises in healthy volunteers.

Venous thromboembolism prophylaxis is crucial. To facilitate active ankle movement in postoperative and bedridden patients, we developed a novel leg exercise apparatus (LEX). We investigated the effect of the LEX by comparing increases in lower extremity venous flow during different modes of exercise using the LEX. In eight healthy participants, we measured venous flow volume and velocity in the femoral vein using duplex ultrasonography at 1, 10, 20, and 30 min after completing three modes of 1-min LEX exercises. The exercises involved (1) rapid single motion (ankle dorsi-plantar flexion; 60 cycles/min); (2) slow single motion (30 cycles/min); and (3) slow combined leg motion. Flow volumes after modes 1, 2, and 3 were 1.63-, 1.39-, and 1.53-fold above baseline at 30 min, respectively. Short periods of rapid single motion, with the LEX, improved postexercise lower extremity venous flow volumes at 30 min and mean venous flow velocity at 20 min, compared to slow single motion exercise. Even at slow speeds, combined-motion improved flow volume compared to single motion. Short periods of rapid single motion exercise, with the LEX, improved postexercise venous flow volumes in the lower extremities at 30 min and mean venous flow velocity at 20 min. These effects were greater than those produced by slow single motion exercises. However, even at slow speeds, combined-motion exercises improved flow volume compared to single motion. Therefore, LEX may prove effective at preventing thromboembolism in postoperative and bedridden patients.

Cardiovascular and Muscular Consequences of Work-Matched Interval-Type of Concentric and Eccentric Pedaling Exercise on a Soft Robot.

Eccentric types of endurance exercise are an acknowledged alternative to conventional concentric types of exercise rehabilitation for the cardiac patient, because they reduce cardiorespiratory strain due to a lower metabolic cost of producing an equivalent mechanical output. The former contention has not been tested in a power- and work-matched situation of interval-type exercise under identical conditions because concentric and eccentric types of exercise pose specific demands on the exercise machinery, which are not fulfilled in current practice. Here we tested cardiovascular and muscular consequences of work-matched interval-type of leg exercise (target workload of 15 sets of 1-min bipedal cycles of knee extension and flexion at 30 rpm with 17% of maximal concentric power) on a soft robotic device in healthy subjects by concomitantly monitoring respiration, blood glucose and lactate, and power during exercise and recovery. We hypothesized that interval-type of eccentric exercise lowers strain on glucose-related aerobic metabolism compared to work-matched concentric exercise, and reduces cardiorespiratory strain to levels being acceptable for the cardiac patient. Eight physically active male subjects (24.0 years, 74.7 kg, 3.4 L O2 min−1), which power and endurance performance was extensively characterized, completed the study, finalizing 12 sets on average. Average performance was similar during concentric and eccentric exercise (p = 0.75) but lower than during constant load endurance exercise on a cycle ergometer at 75% of peak aerobic power output (126 vs. 188 Watt) that is recommended for improving endurance capacity. Peak oxygen uptake (−17%), peak ventilation (−23%), peak cardiac output (−16%), and blood lactate (−37%) during soft robotic exercise were lower during eccentric than concentric exercise. Glucose was 8% increased after eccentric exercise when peak RER was 12% lower than during concentric exercise. Muscle power and RFD were similarly reduced after eccentric and concentric exercise. The results highlight that the deployed interval-type of eccentric leg exercise reduces metabolic strain of the cardiovasculature and muscle compared to concentric exercise, to recommended levels for cardio-rehabilitation (i.e., 50–70% of peak heart rate). Increases in blood glucose concentration indicate that resistance to contraction-induced glucose uptake after the deployed eccentric protocol is unrelated to muscle fatigue.

Resistance exercise recovers the structure of cartilage and synovial membrane of the ankle joint of rats after sciatic compression

Abstract Aim to determine the effects of sciatic compression and treatment with resistance exercise on the morphology of the ankle joint of Wistar rats. Methods 32 male rats, aged 10 ± 1 week, weighing 376±22 grams were divided into the following four groups (n=8/group): CG (control), LG (lesion), EG (exercise) and LEG (lesion and exercise). Three days after sciatic compression, the animals in the EG and LEG were submitted to resistance exercise by climbing stairs (five days/week) for three weeks and a load of 100 grams was added. The exercise was carried out in two sets of ten consecutive ascents of the steps. The ankle joint tissues were analyzed for their morphometry and morphology using light microscopy. Results Regarding the number of chondrocytes, the LG and EG had more cells in the anterior articular cartilage in the tibia (62 and 43%) and in the talus (57 and 45%) when compared to the CG. In the LEG there was a 25% and 26% reduction of chondrocytes in the anterior cartilage in the tibia and talus when compared to the LG. Changes were observed in the tibia and talus in the LG, with the presence of flocculation, invagination of the subchondral bone, discontinuity of tidemark and pannus covering the subchondral bone in the talus, as well as changes in the synovial membrane. These alterations were minimized in the articular cartilage and synovial membrane in the LEG. Conclusions exercise restores the tissue morphology of ankle joint in Wistar rats after sciatic compression.

Effect of acute ambient temperature exposure on cardio-pulmonary and respiratory kinetics in men

Aim: The goal of the study was to compare the kinetic responses of heart rate (HR) and pulmonary (V̇O2pulm) and muscular (V̇O2musc) oxygen uptake during dynamic leg exercise across different acute ambient temperature conditions in a climatic chamber.Methods: Thirteen physically healthy, active, male volunteers demonstrated pseudorandom binary sequence (PRBS) work rate (WR) changes between 30 and 80 W at 15 °C, 25 °C and 35 °C, respectively. HR was measured beat-to-beat using an echocardiogram and V̇O2pulm by breath-by-breath gas exchange; V̇O2musc estimations were assessed by applying a circulatory model and cross-correlation functions.Results: No significant differences were observed across the various temperature conditions in each case for HR, V̇O2pulm or V̇O2musc kinetics (p > 0.05). Baroreflex regulation based on HR kinetics does not seem to be influenced between ambient temperatures of 15 °C and 35 °C during dynamic exercise.Conclusions: The results imply that ambient temperatures of 15 °C, 25 °C and 35 °C have no effect on HR, V̇O2pulm or V̇O2musc kinetics during dynamic moderate exercise. The applied approach may be of interest for assessments of the cardio-pulmonary and respiratory health statuses of individuals working or performing sports in extreme temperature environments. Furthermore, differentiation between systemic (e.g. cardio-dynamic: HR) and specific (e.g. exercising tissues: V̇O2musc) determinants of the relevant physiological systems may improve the evaluation of an individual’s health status.

Comparable Neutrophil Responses for Arm and Intensity-matched Leg Exercise.

Arm exercise is performed at lower absolute intensities than lower body exercise. This may impact on intensity-dependent neutrophil responses, and it is unknown whether individuals restricted to arm exercise experience the same changes in the neutrophil response as found for lower body exercise. Therefore, we aimed to investigate the importance of exercise modality and relative exercise intensity on the neutrophil response. Twelve moderately trained men performed three 45-min constant load exercise trials after determination of peak oxygen uptake for arm exercise (V˙O2peak arms) and cycling (V˙O2peak legs): 1) arm cranking exercise at 60% V˙O2peak arms, 2) moderate cycling at 60% V˙O2peak legs, and 3) easy cycling at 60% V˙O2peak arms. Neutrophil numbers in the circulation increased for all exercise trials, but were significantly lower for easy cycling when compared with arm exercise (P = 0.009), mirroring the blunted increase in HR and epinephrine during easy cycling. For all trials, exercising HR explained some of the variation of the neutrophil number 2 h postexercise (R = 0.51-0.69), epinephrine explaining less of this variation (R = 0.21-0.34). The number of neutrophils expressing CXCR2 decreased in the recovery from exercise in all trials (P < 0.05). Arm and leg exercise elicits the same neutrophil response when performed at the same relative intensity, implying that populations restricted to arm exercise might achieve a similar exercise induced neutrophil response as those performing lower body exercise. A likely explanation for this is the higher sympathetic activation and cardiac output for arm and relative intensity-matched leg exercise when compared with easy cycling, which is partly reflected in HR. This study further shows that the downregulation of CXCR2 may be implicated in exercise-induced neutrophilia.

Energy cost of isolated resistance exercises across low- to high-intensities.

This study aimed to estimate the energy cost across various intensities at eight popular resistance exercises: half squat, 45° inclined leg press, leg extension, horizontal bench press, 45° inclined bench press, lat pull down, triceps extension and biceps curl. 58 males (27.5 ± 4.9 years, 1.78 ± 0.06 m height, 78.67 ± 10.7 kg body mass and 11.4 ± 4.1% estimated body fat) were randomly divided into four groups of 14 subjects each. For each group, two exercises were randomly assigned and on different days, they performed four bouts of 5-min constant-intensity for each of the two assigned exercises: 12%, 16%, 20% and 24% 1-RM. Later, the subjects performed exhaustive bouts at 80% 1-RM in the same two exercises. The mean values of VO2 at the last 30s of exercise at 12, 16, 20 and 24% 1-RM bouts were plotted against relative intensity (% 1-RM) in a simple linear regression mode. The regressions were then used to predict O2 demand for the higher intensity (80% 1-RM). Energy cost rose linearly with exercise intensity in every exercise with the lowest mean values were found in biceps curl and the highest in half squat exercise (p<0.001). Half squat exercise presented significant (p<0.001) higher values of energy cost in all intensities, when compared with the remaining exercises. This study revealed that low-intensity resistance exercise provides energy cost comprised between 3 and 10 kcal∙min-1. Energy cost rose past 20 kcal∙min-1 at 80% 1-RM in leg exercise. In addition, at 80% 1-RM, it was found that upper body exercises are less anaerobic than lower-body exercises.

Lower Leg Anatomical Correlates to Performance and Metabolism from Flywheel-based Exercise

Abstract Lower leg exercises are impacted by the anatomy of the triceps surae-Achilles tendon complex. Such exercises may utilize series elastic energy (SEE), temporarily stored within the Achilles tendon, to augment forces exerted by the triceps surae. While SEE's contribution to bipedal jumping and walking have been assessed, other lower leg exercises yet to receive similar scrutiny include seated calf presses done on flywheel-based hardware. Current subjects did two identical calf press workouts on a flywheel ergometer. The following three variables were obtained from workouts–the total work (TW) performed, net energy costs, and peak blood lactate concentration ([BLa−]). With multivariate regression, four variables correlated with each criterion measures’ variance–lower leg length (LLL) and cross-sectional area (CSA), as well as the lengths of the triceps surae (ML) and Achilles tendon (ATL). Our predictor variables correlated to significant amounts of TW and net energy cost, but not [BLa−] variance. Univariate matrices showed CSA was the best overall predictor for our criterion measures, while ML and ATL were generally weaker correlates. ATL did not have as great an impact as with other lower leg exercises; likely because the slow rate of ankle joint movement greatly limited SEE activity. The limited degree of foot support for ergometer repetitions was also a factor that likely weakened ATL's impact as a correlate. More research on anatomy's impact on this novel form of exercise is warranted.

Distinctive Steady-State Heart Rate and Blood Pressure Responses to Passive Robotic Leg Exercise during Head-Up Tilt: A Pilot Study in Neurological Patients.

Introduction: Robot-assisted tilt table therapy was proposed for early rehabilitation and mobilization of patients after diseases such as stroke. A robot-assisted tilt table with integrated passive robotic leg exercise (PE) mechanism has the potential to prevent orthostatic hypotension usually provoked by verticalization. In a previous study with rather young healthy subjects [average age: 25.1 ± 2.6 years (standard deviation)], we found that PE effect on the cardiovascular system depends on the verticalization angle of the robot-assisted tilt table. In the current study, we investigated in an older population of neurological patients (a) whether they show the same PE effects as younger healthy population on the cardiovascular system at different tilt angles, (b) whether changing the PE frequency (i.e., stepping speed) influences the PE effect on the cardiovascular system, (c) whether PE could prevent orthostatic hypotension, and finally, (d) whether PE effect is consistent from day to day.Methods: Heart rate (HR), and systolic and diastolic blood pressures (sBP, dBP) in response to PE at two different tilt angles (α = 20°, 60°) with three different PE frequencies (i.e., 0, 24, and 48 steps per minute) of 10 neurological patients [average age: 68.4 ± 13.5 years (standard deviation)] were measured on 2 consecutive days. Linear mixed models were used to develop statistical models and analyze the repeated measurements.Results: The models show that: PE significantly increased sBP and dBP but had no significant effect on HR. (a) Similar to healthy subjects the effect of PE on sBP was dependent on the tilt angle with higher tilt angles resulting in a higher increase. Head-up tilting alone significantly increased HR and dBP but resulted in a non-significant drop in sBP. PE, in general, had a more additive effect on increasing BP. (b) The effect of PE was not influenced by its speed. (c) Neither during head-up tilt alone nor in combination with PE did participants experience orthostatic hypotension. (d) The measurement day was not a statistically significant factor regarding the effects of verticalization and PE on the cardiovascular response.Conclusion: We provide evidence that PE can increase steady-state values of sBP and dBP in neurological patients during head-up tilt. Similar to healthy subjects the effect on sBP depends on the verticalization angle of the robot-assisted tilt table. PE might have the potential to prevent orthostatic hypotension, but as the amount of drop in BP in response to head-up tilting was not leading to orthostatic hypotension in our patients, we could neither conclude nor reject such a preventive compensatory effect. Furthermore, we found that changing the PE speed does not influence the steady-state cardiovascular response.

Design, Modeling, and Control of a Portable Leg Rehabilitation System

In this work, a novel design of a portable leg rehabilitation system (PLRS) is presented. The main purpose of this paper is to provide a portable system, which allows patients with lower-limb disabilities to perform leg and foot rehabilitation exercises anywhere without any embarrassment compared to other devices that lack the portability feature. The model of the system is identified by inverse kinematics and dynamics analysis. In kinematics analysis, the pattern of motion of both leg and foot holders for different modes of operation has been investigated. The system is modeled by applying Lagrangian dynamics approach. The mathematical model derived considers calf and foot masses and moment of inertias as important parameters. Therefore, a gait analysis study is conducted to calculate the required parameters to simulate the model. Proportional derivative (PD) controller and proportional-integral-derivative (PID) controller are applied to the model and compared. The PID controller optimized by hybrid spiral-dynamics bacteria-chemotaxis (HSDBC) algorithm provides the best response with a reasonable settling time and minimum overshot. The robustness of the HSDBC–PID controller is tested by applying disturbance force with various amplitudes. A setup is built for the system experimental validation where the system mathematical model is compare with the estimated model using system identification (SI) toolbox. A significant difference is observed between both models when applying the obtained HSDBC–PID controller for the mathematical model. The results of this experiment are used to update the controller parameters of the HSDBC-optimized PID.

Characterization of Ventilatory Off-Kinetics Following Arm and Leg Cycling in Incomplete Spinal Cored Injured Men

INTRODUCTION: The minute ventilation (VE) off-kinetics phase has been associated with greater muscle oxygen deficiency and slower muscle oxygen adjustments to exercise. Neural mechanisms are implicated in VE off-kinetics as recovery from exercise may be mediated by breathing frequency. Motor incomplete spinal cord injury (miSCI) is associated with significant cardiopulmonary impairment that may alter the off-kinetic response during arm and leg exercise. PURPOSE: The purpose of this study was to characterize the VE off-kinetics following both arm and leg exercises in adults with cervical miSCI compared to a group of age matched peers (CON). PARTICIPANTS: miSCI: Age: 31 (18.1) years, Height 185.7 (6.0) cm, Weight 75.9 (14.4) kg. CON: Age: 32 (4.6) years, Height: 178(3.6)cm, Weight 92.9(16.3) kg. METHODS: Both groups completed arm and leg cycle tests on separate days at an intensity that elicited a VE equal to 30% of measured maximum voluntary ventilation (MVV% L·min-1). VE off-kinetics was analyzed over the 5 minutes following the 30% MVV bout using a mono-exponential model. Amplitude (Amp), in liters (L), was defined as the change from exercise to steady state of asymptote approaching baseline and tau(τ)(seconds) as the time taken to reach 63% of the of the end-recovery amplitude. RESULTS: miSCI group: τ(s) and Amp(L) for arm and leg cycling were as follows: 67.9(9.8) and -20.5 (11.53), and 101.6 (19.5) and -23.4(14.5). The average arm τ was 33.7(29.27) faster than leg cycling with a 2.8(9.41) liter decrease in amplitude. CON group: τ(s) and Amp(L) for arm and leg cycling were as follows: 56.7(5.9) and -43.4(4.4) and 90.13 (17.83) and -49.2(4.9), respectively. On average, arm τ was 33.39(16.5) seconds faster than leg cycling while the Amp was 5.8(3.29) liters lower. On average, τ was 11.19 and 11.50 s slower for arm and leg cycling, respectively when compared to CON. Amplitude was also lower with 22.8 and 25.8 liter difference in arm and leg cycling, respectively. CONCLUSION: The miSCI group reported a longer τ following both arm and leg exercise than the CON group suggesting a prolonged recovery phase. A prolonged VE off-kinetic phase may, in part, contribute to reduced functional performance in adults with chronic miSCI. Character count w/o spaces: 1907/2000.