Treadmill Speed Research Articles

Control of Forelimb and Hindlimb Movements and Their Coordination during Quadrupedal Locomotion across Speeds in Adult Spinal Cats.

Coordinating the four limbs is critical for terrestrial mammalian locomotion. Thoracic spinal transection abolishes neural communication between the brain and spinal networks controlling hindlimb/leg movements. Several studies have shown that animal models of spinal transection (spinalization), such as mice, rats, cats, and dogs recover hindlimb locomotion with the forelimbs stationary or suspended. We know less on the ability to generate quadrupedal locomotion after spinal transection, however. We collected kinematic and electromyography data in four adult cats during quadrupedal locomotion at five treadmill speeds before (intact cats) and after low-thoracic spinal transection (spinal cats). We show that adult spinal cats performed quadrupedal treadmill locomotion and modulated their speed from 0.4 m/sec to 0.8 m/sec but required perineal stimulation. During quadrupedal locomotion, several compensatory strategies occurred, such as postural adjustments of the head and neck and the appearance of new coordination patterns between the forelimbs and hindlimbs, where the hindlimbs took more steps than the forelimbs. We also observed temporal changes, such as shorter forelimb cycle/swing durations and shorter hindlimb cycle/stance durations in the spinal state. Forelimb double support periods occupied a greater proportion of the cycle in the spinal state, and hindlimb stride length was shorter. Coordination between the forelimbs and hindlimbs was weakened and more variable in the spinal state. Changes in muscle activity reflected spatiotemporal changes in the locomotor pattern. Despite important changes in the pattern, our results indicate that biomechanical properties of the musculoskeletal system play an important role in quadrupedal locomotion and offset some of the loss in neural communication between networks controlling the forelimbs and hindlimbs after spinal transection.

Contribution of Genetic Background to Vascular Adaptation to Exercise Training Based on Critical Speed of Different Intensities

An impaired endothelial function is a fundamental component of the pathogenesis of cardiovascular disease. In mice, exercise training is well‐known to improve cardiorespiratory fitness and endothelial function. However, the post exercise training effect on endothelial function varies among different strains of mice, suggesting that genetic background contributes to the heterogeneous effect of exercise on vascular health. NZW/LacJ (NZW) mice are known as relatively low responders to exercise training compared to high responder strains such as FVB/NJ (FVB). NZW mice also have relatively poor endothelial function in thoracic aorta when compared with other mouse strains. Therefore, we aimed to determine the contribution of genetic background to endothelial adaptation to exercise training in FVB and NZW mice. Vasoreactivity was assessed in femoral arteries from female mice from both strains (NZW and FVB) after 6 weeks of training using two different critical speed (CS) treadmill training intensities. Mice from each strain were randomly assigned to one of three groups: sedentary (SED), 80% of CS training (CS80), and 90% of CS (CS90) training. After training, endothelium‐dependent vasorelaxation to acetylcholine (ACh) and endothelium‐independent vasorelaxation to sodium nitroprusside (SNP) were measured as well as the vasocontractile responses to phenylephrine (PE) and potassium chloride (KCl). Maximal relaxation responses and IC50 for ACh and SNP were similar between NZW groups (SED, CS80, and CS90). In femoral arteries from FVB mice, there were no differences for maximal relaxation to ACh, but there was significant difference in IC50 for ACh‐induced vasorelaxation between SED vs. CS90 groups (p=0.05). Maximal responses to ACh were similar between NZW and FVB; however, IC50 was significantly lower in FVB compared with NZW, indicating that sensitivity to ACh is greater in arteries from FVB. There was a significant strain‐dependent difference for IC50 for SNP despite no strain differences for maximal responses. There was no effect of exercise or strain on contractile responses to PE and KCl, although the EC50 for KCl induced vasocontraction was higher (p=0.0329) in NZW. Treadmill exercise training at 80% or 90% CS did not contribute to improved vasomotor function in NZW while higher intensity exercise improved sensitivity to ACh in arteries from FVB. Genetic background did not significantly impact vasomotor function or endothelial responses to exercise training in FVB and NZW mice.

Run for Your Life: A Meta‐Analysis of the Effects of Exercise Intensity on Cardiovascular Outcomes in a Rat Model of Hypertension

ObjectiveHypertension increases the risk of pulmonary embolism, stroke, heart attack, and death. To prevent these events in hypertensive patients, regular exercise has been recommended as a nonpharmacological intervention for decades, but it is still not well understood whether cardiovascular benefits vary with exercise intensity. In this meta‐analysis, we explored the effect of treadmill running intensity on systolic blood pressure (SBP), mean arterial pressure (MAP), and resting heart rate (RHR) in a rat model of hypertension, known as spontaneously hypertensive rats (SHR).MethodsA SciFinder Scholar database search returned 817 comparative studies, of which 72 (1505 rats) were included for quantitative analysis. Studies were characterized as low, moderate, or high intensity based on treadmill speed setting or, where available, %VO2max. Aggregate means and standard errors for SBP, MAP, and RHR were extracted and subjected to one‐way ANOVA with post‐hoc Tukey’s test using GraphPad Prism 9.ResultsWhen compared to sedentary hypertensive controls, both low and moderate‐intensity treadmill exercise yielded significant reductions in SBP, MAP, and RHR, but high‐intensity exercise did not. Although the greatest improvement in SBP, MAP, and RHR resulted from low‐intensity treadmill exercise, no statistically significant difference was found between training intensity levels for these cardiovascular outcomes.ConclusionsLow and moderate‐intensity, steady‐state treadmill sessions over several weeks reduced blood pressure and resting heart rate in hypertensive subjects. The failure of high‐intensity exercise to improve cardiovascular outcomes may suggest a role played by oxidative stress and merits further investigation. Overall, these preliminary results suggest that even low‐intensity exercise may serve as a beneficial tool that positively impacts cardiovascular outcomes in chronic hypertension.

Feasibility of a hip flexion feedback system for controlling exercise intensity and tibia axial peak accelerations during treadmill walking

The ability to meet high exercise intensities is limited by the increased risk of injury in some clinical populations. Previous studies have linked large tibia peak positive accelerations resulting from running to increased risk of developing lower-extremity injury. The purpose of this study is to determine the feasibility of using a hip flexion feedback system (HFFS) to meet and maintain different exercise intensities while maintaining low tibia axial accelerations. Ten healthy participants were tested on a HFFS test and an independent walking/running test to meet exercise intensities of 40% and 60% of heart rate reserve (HRR). During the HFFS test, the HFFS controlled in real time the exercise intensity by directing individuals to specific maximum hip flexion targets during walking and providing visual information that assists them in maintaining low tibia peak positive accelerations during the initial contact phase. Maximum hip flexion targets during walking are calculated based on real-time readings of the participant’s heart rate. During the independent test, exercise intensity was controlled independently by the participant using treadmill speed. Compared to the independent test, using the HFFS at 60% HRR resulted in similar heart-rate error but lower tibia peak positive accelerations. No differences were observed for the 40% HRR intensity. This paper describes a novel exercise approach that uses the individual’s heart rate to calculate maximal hip flexion targets that an individual should meet during treadmill walking. The HFFS also provides tibia peak positive peak acceleration cues. Therefore, the HFFS can increase and control exercise intensities while maintaining low tibia accelerations. In particular, the HFFS might be an alternative strategy to meet moderate to vigorous exercise intensities in populations at risk of developing lower-extremity injuries.

Optimising the Dyspnoea Challenge: exertional dyspnoea responses to changing treadmill gradients

BackgroundThe Dyspnoea Challenge is a two-minute treadmill walk designed to measure exertional dyspnoea(ED). To efficiently individualise workload, we aimed to assess; 1) whether the Dyspnoea Challenge is responsive to 1% changes in treadmill gradient and 2) the minimum gradient variation necessary to generate a clinically meaningful change in ED (≥1 modified Borg scale). MethodsThirty individuals with COPD(GOLD II-IV) (age: 69.2 ± 9.2 years; FEV1: 49.3 ± 19.1%) completed six Dyspnoea Challenges at a fixed treadmill speed of 3 km·h−1 and at a gradient of between 3% and 8%, performed in random order. ED intensity and leg fatigue were measured using the 0–10 modified Borg scale. Heart rate(HR) and oxygen saturation(SpO2) were monitored continuously. A multidimensional dyspnoea profile(MDP) was used to quantify the discomfort, physical, e.g., work/effort and breathing frequency, and emotional components of ED. ResultsHigher treadmill gradients generated stronger intensities of ED (3%:2.6 ± 1.8; 4%:2.8 ± 2.2; 5%:3.2 ± 2.2; 6%:3.4 ± 2.2; 7%:3.7 ± 1.8; 8%:4.0 ± 2.1units). Statistical changes were observed in ED(e.g.,3 vs. 5%: P = .03) and the MDP discomfort data(e.g.,4 vs. 6%: P = .04) at ≥ a 2% variation in treadmill gradient. Linear regression found a 4% variation in treadmill gradient corresponded to a rise in ED ≥ 1unit. Increases in ED intensity corresponded to heightened sensations of work/effort(P < .01) and breathing frequency(P < .01). There were no changes in emotional constructs(P = .27). While there was an increase in HR with increasing gradient(P < .01), no differences were observed in end-exercise SpO2(P = .79) or leg fatigue(P = .06). ConclusionTo significantly change ED, the treadmill gradient must be manipulated by ≥ 2%, with a ≥ 4% change in gradient required to induce a clinically meaningful change in ED.

Effect of 32-Weeks High-Intensity Interval Training and Resistance Training on Delaying Sarcopenia: Focus on Endogenous Apoptosis.

Sarcopenia caused by aging is an important factor leading to a decline in the quality of life of older people. Apoptosis in muscle atrophy accelerates the process of muscle loss in older populations. The present study aimed to investigate the effects of 32 weeks of high-intensity interval training (HIIT) and resistance training (RT) on the skeletal muscle-related indices and provide a theoretical basis for regulating the mitochondrial-mediated pathway to delay sarcopenia. We randomly selected 10 from eight-month-old male SD rats (N = 130) as the baseline group; after 1 week of adaptive feeding, the rats were sacrificed. The remaining rats were randomly assigned to one of three groups: control group (C, N = 40, natural aging for 32 weeks), HIIT group (H, N = 40, performed six loops of 3 min at 90% and 3 min at 50% VO2 max speed treadmill running, with 5 min at 70% VO2 max speed at the beginning and the end of the training, 3 times a week for 32 weeks), and resistance group (R, n = 40, 46 min per day, 3 days per week, with a 30% maximum load on a treadmill with a slope of 35°, 15 m/min). The soleus muscles were collected for analysis at baseline and every 8 weeks. Aging resulted in decreased soleus muscle mass and Bcl-2 levels in the mitochondria, while the levels of reactive oxygen species (ROS) and Bax did not change. HIIT reversed the age-associated activation of pro-apoptotic processes, but RT did not. In addition, when rats were aged from 8 to 16 months, the level of Cyt-C did not change, the Caspase-9 levels and Caspase-3 levels decreased gradually in the soleus muscles, the rats of both the HIIT and RT groups had these indices decreased at 32 weeks. The results suggest that the age-associated loss of muscle mass was reversed by training, and the effect of RT was better than that of HIIT. Both the HIIT and RT rats showed a decrease in the apoptosis of skeletal muscle cells after 32 weeks of intervention. HIIT performed better for long-term intervention regarding the pro-apoptotic factors. This study warranted further research to delineate the underlying mechanism of effects of different exercise methods on the changes of aging skeletal muscle at in vivo level.

Psychophysiological Responses to Self-Selected Exercise Intensity Over the Menstrual Cycle: A Randomized Crossover Phase Trial

ABSTRACT Purpose: This study investigated the psychophysiological responses during self-selected exercise intensity over the course of the menstrual cycle (MC). Methods: Seventeen healthy women with regular MCs completed three randomized treadmill bouts of 30 min of self-selected exercise intensity during menstruation, mid-follicular, and late luteal phases. Anxiety, menstrual distress (i.e., pain, behavior change, autonomic reaction, fluid retention, and negative affect) and profile of mood (i.e., tension, depression, and anger) were measured before exercise. Arousal, heart rate (HR), motivation, rating of perceived exertion and affective valence were measured before, during and after each exercise session. Results: Anger, anxiety, behavior change, pain, and negative affect were significantly greater (p < .05) during menstruation compared to the mid-follicular phase, whereas fluid retention, anger, behavior change, and autonomic reaction were greater (p < .05) during the late luteal phase compared with the mid-follicular phase. Participants felt more negative affective valence and less motivation to start exercise during menstruation compared with other MC phases. Average treadmill speed (5.8 ± 1.1 vs 6.0 ± 0.7 vs 5.9 ± 0.7 km/h–1, p = .36) and %HRmax (74.9 ± 3.2 vs 77.8 ± 5.4 vs 77.4 ± 7.1%, p = .40) did not differ between menstruation, mid-follicular, and late luteal phases. Also, noteworthy is that participants self-selected an intensity that exceeded the minimum levels recommended for health and cardiorespiratory fitness promotion (64–70% HRmax). Conclusions: Results of this study indicate that psychophysiological responses are negatively impacted mainly during menstruation and the late luteal phase of the MC. These findings may be helpful for professionals who work to promote the initiation and maintenance of exercise in women.

Deep Learning Enables Exoboot Control to Augment Variable-Speed Walking

Ankle exoskeletons have the potential to improve mobility, but common controllers are often inflexible to variations in tasks, such as changes in walking speed. To enable effective variable-speed exoboot control, we developed and validated a two-headed convolutional neural network trained to (1) classify stance versus swing and (2) predict the phase during stance, which was then mapped to a desired exoboot torque. This Machine Learning Estimator (MLE) was trained from nine participants walking at three speeds and four exoboot assistance levels. A Time-Based Estimator (TBE) that predicted gait phase from the two previous stride durations was used to apply realistic torques during MLE training and served as a within&#x2013;participant control condition. The MLE was validated online with three new participants walking at a range of speeds and torques, both interpolating within and extrapolating outside the training set. Online validation accuracy (RMSE) across tested speeds and torque levels was 3.9&#x0025;. On a simple walking task in which treadmill speed was varied sinusoidally between 1.1 and 1.6 m&#x002F;s with a 30 s period, the three participants exhibited a mean 5.2&#x0025; decrease in metabolic expenditure with the MLE compared to no-exo (boots only), but exhibited a 5.4&#x0025; increase when walking with the TBE. The MLE more accurately predicted heel strike and toe off events (heel strike Mean Absolute Error: 9.6 ms; toe off MAE: 13.2 ms) than the TBE (heel strike MAE: 19.1 ms; toe off MAE: 34 ms). These positive results validated the potential of using a deep learning model for gait state estimation to effectively control an ankle exoskeleton across variable walking speeds.

An Experimental Feasibility Study Evaluating the Adequacy of a Sportswear-Type Wearable for Recording Exercise Intensity.

Sportswear-type wearables with integrated inertial sensors and electrocardiogram (ECG) electrodes have been commercially developed. We evaluated the feasibility of using a sportswear-type wearable with integrated inertial sensors and electrocardiogram (ECG) electrodes for evaluating exercise intensity within a controlled laboratory setting. Six male college athletes were asked to wear a sportswear-type wearable while performing a treadmill test that reached up to 20 km/h. The magnitude of the filtered tri-axial acceleration signal, recorded by the inertial sensor, was used to calculate the acceleration index. The R-R intervals of the ECG were used to determine heart rate; the external validity of the heart rate was then evaluated according to oxygen uptake, which is the gold standard for physiological exercise intensity. Single regression analysis between treadmill speed and the acceleration index in each participant showed that the slope of the regression line was significantly greater than zero with a high coefficient of determination (walking, 0.95; jogging, 0.96; running, 0.90). Another single regression analysis between heart rate and oxygen uptake showed that the slope of the regression line was significantly greater than zero, with a high coefficient of determination (0.96). Together, these results indicate that the sportswear-type wearable evaluated in this study is a feasible technology for evaluating physical and physiological exercise intensity across a wide range of physical activities and sport performances.

Hybrid Zero Dynamics Control of an Underactuated Lower-Limb Exoskeleton for Gait Guidance

Abstract Hybrid zero dynamics (HZD) control creates dynamically stable gaits by driving a hybrid robot model toward an optimally generated state-dependent reference signal. This paper presents the first application of HZD to an underactuated lower-limb exoskeleton for gait guidance. A phase-based reference gait is generated to follow a nominal walking pattern. Simulation results using a phase-based proportional-derivative (PD) controller validate that stable periodic gait similar to nominal gait is possible for the identified human-exoskeleton model. For hardware application, a bilateral mixing strategy is taken to accommodate the presence of the double support phase, which was assumed to be instantaneous in the hybrid model. A treadmill experiment is conducted with a healthy subject using the Indego Explorer exoskeleton. Comparing the recorded gait to the optimal phase-based reference, the root-mean-square joint tracking errors (RMSE) are 2.87 deg, 2.79 deg, 3.20 deg, and 11.0 deg at the stance hip, stance knee, swing hip, and swing knee, respectively. Similarly, compared to the commanded reference, the RMSE are 2.04 deg, 4.40 deg, 4.58 deg, and 6.83 deg, respectively. A second experiment was conducted wherein the treadmill speed varied from 0.3 to 0.5 m/s. The results show how the HZD controller exhibits remarkable flexibility and robustness for multiple walking speeds and grants the operator greater level of volitional control due to the time-invariant, phase-based nature of the implementation. Taken altogether, the presented results suggest that HZD control can serve as a rehabilitative control method capable of providing gait guidance in underactuated exoskeleton systems.

The effect of intermittent vs. continuous walking on distance to fatigue in persons with multiple sclerosis

Purpose Previous studies provided evidence that persons with Multiple Sclerosis (pwMS) who walk intermittently experience less fatigue and walk longer distances than when walking continuously. However, total distance pwMS can walk in either condition is unknown. We examined time and distance to fatigability in pwMS comparing intermittent walking (IW) to continuous walking (CW). Materials and Methods 18 pwMS, with Expanded Disability Status Scale median of 4.75 [range = 2–6.5, IQR = 2.5] participated in this randomized crossover study. The IW condition consisted of alternating 30 s treadmill walking and 30 s seated rests. The CW condition consisted of treadmill walking without breaks. Treadmill speed (TS) was determined by an overground 2-min walk test. Walking fatigability was determined by participants walking on the treadmill, until gait fatigue was noted by patient or examiners. Total time and distance to gait fatigue, and subjective fatigue as measured by the Visual analog scale of fatigue were recorded. Results Participants had significantly longer duration and distance to fatigue in the IW condition than the CW condition (ps ≤ 0.037). No difference in VASF scores between the two conditions were noted. Conclusion In this sample, IW allowed pwMS to perform a greater volume of walking and can be an option to improve walking endurance in this population. IMPLICATIONS FOR REHABILITATION Multiple sclerosis (MS) is a disease that progressively impacts walking, resulting in a decrease in the maximum distance that a person with MS can walk. Intermittent walking has been shown to improve 6-min walk test performance in persons with MS (pwMS) compared to continuous walking, but its effects on longer and shorter walks is not known. The use of distance to fatigue should be considered a viable option for measuring walking fatigability in pwMS as it does not exclude persons based on their ability to complete a 6-min walk, nor would it be too easy for persons with pwMS with mild disability. By using distance to fatigue as an outcome measure, this study provides evidence that intermittent walking results in less fatigability regardless of walking ability. PwMS, regardless of their walking ability, can walk longer distances intermittently than continuously, suggesting that clinical treatment of walking fatigability in pwMS should utilize intermittent rather than continuous walking training.

Differences between Elite Male and Female Badminton Athletes Regarding Heart Rate Variability, Arterial Stiffness, and Aerobic Capacity.

Cardiovascular health and aerobic capacity play crucial roles in determining the performance of athletes in the highly competitive sport of badminton. Few studies have directly compared heart rate variability (HRV), arterial stiffness, and aerobic capacity between male and female athletes, especially among badminton athletes. This study investigated sex differences in HRV, arterial stiffness, and aerobic capacity in badminton athletes. Elite badminton athletes were recruited and divided into male (n = 20, 21.0 ± 1.8 years old) and female (n = 16, 21.2 ± 2.3 years old) groups. Both groups performed an incremental treadmill running test for the evaluation of maximal oxygen consumption (O2max), anaerobic threshold, and time to exhaustion. They started exercising at a treadmill speed of 2.7 km/h and an inclination of 10% gradient for 3 min, and the speed and inclination were gradually increased every 3 min until they were exhausted or fatigued volitionally. HRV was examined using the Polar heart rate monitor over a period of 5 min at rest in the supine position. Subsequently, the index of arterial stiffness was examined under the same condition. Our results revealed significant differences between the male and female athletes in O2max (men: 60.38 ± 8.98 mL/kg/min, women: 48.13 ± 7.72 mL/kg/min, p < 0.05), anaerobic threshold (men: 41.50 ± 7.26 mL/kg/min, women: 32.51 ± 6.19 mL/kg/min, p < 0.05), time to exhaustion (men: 902.15 ± 120.15 s, women: 780.56 ± 67.63 s, p < 0.05), systolic blood pressure (men: 125.27 ± 7.76 mmHg, women: 107.16 ± 11.09 mmHg, p < 0.05), and arterial stiffness index (men: 63.56 ± 12.55, women: 53.83 ± 8.03, p < 0.05). However, no significant differences in HRV measures were observed between the two groups. These findings suggested that the male badminton athletes demonstrated significantly higher aerobic capacity than did the female athletes, but there were no significant differences in HRV measures. The female athletes exhibited superior arterial function, compared with their male counterparts.

Biomechanical Correlates of Falls Risk in Gait Impaired Stroke Survivors.

Increased falls risk is prevalent among stroke survivors with gait impairments. Tripping is the leading cause of falls and it is highly associated with mid-swing Minimum Foot Clearance (MFC), when the foot’s vertical margin from the walking surface is minimal. The current study investigated MFC characteristics of post-stroke individuals (n = 40) and healthy senior controls (n = 21) during preferred speed treadmill walking, using an Optotrak 3D motion capture system to record foot-ground clearance. In addition to MFC, bi-lateral spatio-temporal gait parameters, including step length, step width and double support time, were obtained for the post-stroke group’s Unaffected and Affected limb and the control group’s Dominant and Non-dominant limbs. Statistical analysis of MFC included central tendency (mean, median), step-to-step variability (standard deviation and interquartile range) and distribution (skewness and kurtosis). In addition, the first percentile, that is the lowest 1% of MFC values (MFC 1%) were computed to identify very high-risk foot trajectory control. Spatio-temporal parameters were described using the mean and standard deviation with a 2 × 2 (Group × Limb) Multivariate Analysis of Variance applied to determine significant Group and Limb effects. Pearson’s correlations were used to reveal any interdependence between gait variables and MFC control. The main finding of the current research was that post-stroke group’s affected limb demonstrated lower MFC 1% with higher variability and lower kurtosis. Post-stroke gait was also characterised by shorter step length, larger step width and increased double support time. Gait retraining methods, such as using real-time biofeedback, would, therefore, be recommended for post-stroke individuals, allowing them to acquire optimum swing foot control and reduce their tripping risk by elevating the swing foot and improving step-to-step consistency in gait control.

State- and Condition-Dependent Modulation of the Hindlimb Locomotor Pattern in Intact and Spinal Cats Across Speeds.

Locomotion after complete spinal cord injury (spinal transection) in animal models is usually evaluated in a hindlimb-only condition with the forelimbs suspended or placed on a stationary platform and compared with quadrupedal locomotion in the intact state. However, because of the quadrupedal nature of movement in these animals, the forelimbs play an important role in modulating the hindlimb pattern. This raises the question: whether changes in the hindlimb pattern after spinal transection are due to the state of the system (intact versus spinal) or because the locomotion is hindlimb-only. We collected kinematic and electromyographic data during locomotion at seven treadmill speeds before and after spinal transection in nine adult cats during quadrupedal and hindlimb-only locomotion in the intact state and hindlimb-only locomotion in the spinal state. We attribute some changes in the hindlimb pattern to the spinal state, such as convergence in stance and swing durations at high speed, improper coordination of ankle and hip joints, a switch in the timing of knee flexor and hip flexor bursts, modulation of burst durations with speed, and incidence of bi-phasic bursts in some muscles. Alternatively, some changes relate to the hindlimb-only nature of the locomotion, such as paw placement relative to the hip at contact, magnitude of knee and ankle yield, burst durations of some muscles and their timing. Overall, we show greater similarity in spatiotemporal and EMG variables between the two hindlimb-only conditions, suggesting that the more appropriate pre-spinal control is hindlimb-only rather than quadrupedal locomotion.

Smart Eyeglasses: A Valid and Reliable Device to Assess Spatiotemporal Parameters during Gait.

The study aims to determine the validity and reproducibility of step duration and step length parameters measured during walking in healthy participants using an accelerometer embedded in smart eyeglasses. Twenty young volunteers participated in two identical sessions comprising a 30 s gait assessment performed at three different treadmill speeds under two conditions (i.e., with and without a cervical collar). Spatiotemporal parameters (i.e., step duration and step length normalized by the lower limb length) were obtained with both the accelerometer embedded in smart eyeglasses and an optoelectronic system. The relative intra- and inter-session reliability of step duration and step length computed from the vertical acceleration data were excellent for all experimental conditions. An excellent absolute reliability was observed for the eyeglasses for all conditions and concurrent validity between systems was observed. An accelerometer incorporated in smart eyeglasses is accurate to measure step duration and step length during gait.

Preliminary Outcomes of Combined Treadmill and Overground High-Intensity Interval Training in Ambulatory Chronic Stroke.

PurposeLocomotor high-intensity interval training (HIIT) is a promising intervention for stroke rehabilitation. However, overground translation of treadmill speed gains has been somewhat limited, some important outcomes have not been tested and baseline response predictors are poorly understood. This pilot study aimed to guide future research by assessing preliminary outcomes of combined overground and treadmill HIIT.Materials and MethodsTen participants >6 months post-stroke were assessed before and after a 4-week no-intervention control phase and a 4-week treatment phase involving 12 sessions of overground and treadmill HIIT.ResultsOverground and treadmill gait function both improved during the treatment phase relative to the control phase, with overground speed changes averaging 61% of treadmill speed changes (95% CI: 33–89%). Moderate or larger effect sizes were observed for measures of gait performance, balance, fitness, cognition, fatigue, perceived change and brain volume. Participants with baseline comfortable gait speed <0.4 m/s had less absolute improvement in walking capacity but similar proportional and perceived changes.ConclusionsThese findings reinforce the potential of locomotor HIIT research for stroke rehabilitation and provide guidance for more definitive studies. Based on the current results, future locomotor HIIT studies should consider including: (1) both overground and treadmill training; (2) measures of cognition, fatigue and brain volume, to complement typical motor and fitness assessment; and (3) baseline gait speed as a covariate.

Effects of Endurance Training on Motor Signs of Parkinson's Disease: A Systematic Review and Meta-Analysis.

Evidence has demonstrated that endurance training (ET) reduces the motor signs of Parkinson's disease (PD). However, there has not been a comprehensive meta-analysis of studies to date. The aim of this study was to compare the effect of ET versus nonactive and active control conditions on motor signs as assessed by either the Unified Parkinson's Disease Rating Scale part III (UPDRS-III) or Movement Disorder Society-UPDRS-III (MDS-UPDRS-III). A random-effect meta-analysis model using standardized mean differences (Hedges' g) determined treatment effects. Moderators (e.g., combined endurance and physical therapy training [CEPTT]) and meta-regressors (e.g., number of sessions) were used for sub-analyses. Methodological quality was assessed by the Physiotherapy Evidence Database. Twenty-seven randomized controlled trials (RCTs) met inclusion criteria (1152 participants). ET is effective in decreasing UPDRS-III scores when compared with nonactive and active control conditions (g = - 0.68 and g = - 0.33, respectively). This decrease was greater (within- and between-groups average of - 8.0 and - 6.8 point reduction on UPDRS-III scores, respectively) than the moderate range of clinically important changes to UPDRS-III scores (- 4.5 to - 6.7 points) suggested for PD. Although considerable heterogeneity was observed between RCTs (I2 = 74%), some moderators that increased the effect of ET on motor signs decreased the heterogeneity of the analyses, such as CEPTT (I2 = 21%), intensity based on treadmill speed (I2 = 0%), self-perceived exertion rate (I2 = 33%), and studies composed of individuals with PD and freezing of gait (I2 = 0%). Meta-regression did not produce significant relationships between ET dosage and UPDRS-III scores. ET is effective in decreasing UPDRS-III scores. Questions remain about the dose-response relationship between ET and reduction in motor signs.

Overground versus treadmill walking in Parkinson’s disease: Relationship between speed and spatiotemporal gait metrics

BackgroundTreadmills provide a safe and convenient way to study the gait of people with Parkinson’s disease (PD), but outcome measures derived from treadmill gait may differ from overground walking. ObjectiveTo investigate how the relationships between gait metrics and walking speed vary between overground and treadmill walking in people with PD and healthy controls. MethodsWe compared 29 healthy controls to 27 people with PD in the OFF-medication state. Subjects first walked overground on an instrumented gait walkway, then on an instrumented treadmill at 85%, 100% and 115% of their overground walking speed. Average stride length and cadence were computed for each subject in both overground and treadmill walking. ResultsStride length and cadence both differed between overground and treadmill walking. Regressions of stride length and cadence on gait speed showed a log-log relationship for both overground and treadmill gait in both PD and control groups. The difference between the PD and control groups during overground gait was maintained for treadmill gait, not only when treadmill speed matched overground speed, but also with ± 15% variation in treadmill speed from that value. SignificanceThese results show that the impact of PD on stride length and cadence and their relationship to gait speed is preserved in treadmill as compared to overground walking. We conclude that a treadmill protocol is suitable for laboratory use in studies of PD gait therapeutics.

Prescribing walking training in interstitial lung disease from the 6-minute walk test

ABSTRACT Introduction and Objective Endurance training during PR requires exercise prescription at sufficient intensity to achieve physiological benefits. This analysis sought to investigate whether walking training prescribed from 6-minute walk test (6MWT) average speed provides an appropriate training intensity for people with ILD during PR. Methods Individuals with ILD completed cardiopulmonary exercise test (CPET) and 6MWT in random order. A 10-minute constant speed treadmill walk test (10MTW) was undertaken at 80% of the average 6MWT speed. Oxygen uptake (VO2) was measured during all tests. Percentage VO2peak during 10MTW was main outcome measure. Results Eleven people with ILD (age 71 (8) years; forced vital capacity 73 (18) %predicted, 6-minute walk distance 481 (99) meters, and VO2peak during CPET 1.3 (0.2) L.min−1) undertook testing. Average VO2peak during 10MTW was 91 (18) % of CPET VO2peak [range 67–116%]. Participants who achieved a greater VO2peak during CPET walked at a smaller %VO2peak during 10MTW (r = −0.6; p = .04). Conclusions For people with ILD, walking training prescribed at 80% of 6MWT average speed can provide adequate exercise training intensity for PR.

Moderate Exercise and Immune Response in Rats: A Model for Cancer Prevention / Exercício Moderado e Resposta Imune em Ratos: Um Modelo para a Prevenção do Câncer

Exercise is believed to cause changes in population and/or activity of immunocompetent cells. Study of this relationship is difficult in humans because of the multifactorial nature of human physiology and concomitant problems in controlling extraneous variables. We have investigated the effects of 4 weeks of moderate exercise training on percentage of NK cells and Lymphocyte activity in Wistar male rats under tightly controlled laboratory conditions. The animals were randomized into two groups: exercise and control. Exercised rats ran at a treadmill speed of 20 m/min (moderate exercise intensity), for 20 minutes, 6 days/week. Laboratory and handling conditions were matched, and food was controlled for both groups. Twenty-four hours after the exercise training program, lymphocyte response did not change significantly (p&gt;0.05). Exercised rats demonstrated a significant increase in the percentage of circulating NK cell population (p&lt;0.05). Exercise training demonstrated a significantly lower body weight for the exercised rats (p&lt;0.05). With this simple model, this study supports the concept that regular moderate exercise leads to beneficial changes in the immunological response that may prevent cancer.