Speed Increments Research Articles

Locomotor Recovery in Spinal Cord Injury: Insights Beyond Walking Speed and Distance

Recovery of locomotor function after incomplete spinal cord injury (iSCI) is clinically assessed through walking speed and distance, while improvements in these measures might not be in line with a normalization of gait quality and are, on their own, insensitive at revealing potential mechanisms underlying recovery. The objective of this study was to relate changes of gait parameters to the recovery of walking speed while distinguishing between parameters that rather reflect speed improvements from factors contributing to overall recovery. Kinematic data of 16 iSCI subjects were repeatedly recorded during in-patient rehabilitation. The responsiveness of gait parameters to walking speed was assessed by linear regression. Principal component analysis (PCA) was applied on the multivariate data across time to identify factors that contribute to recovery after iSCI. Parameters of gait cycle and movement dynamics were both responsive and closely related to the recovery of walking speed, which increased by 96%. Multivariate analysis revealed specific gait parameters (intralimb shape normality and consistency) that, although less related to speed increments, loaded highly on principal component one (PC1) (58.6%) explaining the highest proportion of variance (i.e., recovery of outcome over time). Interestingly, measures of hip, knee, and ankle range of motion showed varying degrees of responsiveness (from very high to very low) while not contributing to gait recovery as revealed by PCA. The conjunct application of two analysis methods distinguishes gait parameters that simply reflect increased walking speed from parameters that actually contribute to gait recovery in iSCI. This distinction may be of value for the evaluation of interventions for locomotor recovery.

Evaluation of the Best-designed Graded Exercise Test to Assess Peak Treadmill Speed.

This study examined the influence of different speed increments during treadmill exercise tests on peak treadmill speed (Vpeak) and its relationship with a 1-h treadmill running performance. 18 male recreational and amateur runners (10-km running pace: 10-15 km·h(-1)) performed, in an alternate order, 3 continuous incremental exercise tests with different speed increments (0.5, 1.0 and 2.0 km·h(-1)) on a motorized treadmill to determine Vpeak. Thereafter they undertook a 1-h time trial on a treadmill. Vpeak was determined as either (a) the highest speed that could be maintained for a complete minute (Vpeak-60 s), (b) the speed of the last complete stage (Vpeak-C), or (c) the speed of the last complete stage added to the product of the speed increment and the completed fraction of the incomplete stage (Vpeak-P). The Vpeak values were highly influenced by the different speed-incremented rates and the Vpeak-P determined during the protocol comprising speed increments of 1 km·h(-1) presented the highest correlation with 1-h time trial performance (r=0.89). The results suggest that a protocol with speed increments comprising 1 km·h(-1) and with a 3-min stage duration should be used as standard for the determination of Vpeak to assess aerobic fitness and predict endurance performance in recreational runners. Furthermore, the Vpeak-P should be used for the determination of Vpeak.

Peak blood lactate parameters in athletes of different running events during low-intensity recovery after ramp-type protocol.

The aims of this study were to explore the differences in the peak blood lactate concentration (La(peak)) and time to reach Lapeak during low-intensity recovery after an all-out treadmill ramp test in runners of 4 diverse running disciplines and different training regimes and to identify the most opportune sampling time to determine Lapeak in these athlete groups. The participants were 48 Croatian national-level male track runners (10 sprinters [S], fifteen 400-m runners [S4], 10 middle-distance [MD] runners and 13 long-distance [LD] runners). The runners performed an incremental treadmill protocol until volitional exhaustion, with the inclination of 1.5%, and speed increments of 1 km·h(-1) every 60 seconds. During recovery, they walked at 5 km·h(-1) for 5 minutes. Fingertip capillary blood samples were collected at the end of the first, third, and fifth minute of recovery. Peak blood lactate concentration in LD was significantly lower than in runners of other disciplines (10.9 ± 2.4 mmol·L(-1) for LD; 13.7 ± 2.9 for MD; 14.0 ± 1.4 for S4; 15.1 ± 2.7 for S) (p < 0.01). No significant difference was observed among other groups. There was no significant difference in tLa(peak) among the 4 participant groups. In conclusion, LD had a significantly lower La(peak) in comparison to other runners; runners of all disciplines reached La(peak) within the first 2 minutes of recovery.

Reproducibility of heart rate and rating of perceived exertion values obtained from different incremental treadmill tests

Summary Objective The present study aimed to examine the reproducibility of heart rate (HR) and rating of perceived exertion (RPE) values obtained during different incremental treadmill tests. Equipment and methods Twenty male, recreational, endurance-trained runners (10-km running pace: 10–15 km·h −1 ) performed, in a counterbalanced order, three continuous incremental exercise tests with different speed increments (0.5 km·h −1 , 1 km·h −1 and 2 km·h −1 ). Thereafter, each participant performed the three tests again, maintaining the same order as before. The reproducibility of the HR and RPE values were analyzed for all protocols during submaximal intensities (8, 10, 12, and 14 km·h −1 ). In addition, it was examined the reproducibility of maximal HR (HR max ) and peak RPE (RPE peak ). Results The variability of both the HR and RPE values showed a tendency to decrease over the stages during the incremental test and was not or slightly influenced by the incremental test design. The HR at 14 km·h −1 and HR max presented the highest reproducibility (CV 5.0%). In conclusion, the HR values were highly reproducible during the stages of the incremental test, in contrast to the RPE values that presented limited reproducibility.

About offshore resource assessment with floating lidars with special respect to turbulence and extreme events

Offshore resource assessment with lidars on floating platforms is a flexible and particularly cost-effective alternative to the conventional meteorological mast solution, that is considered as onshore state-of-the-art transferred to offshore sites, and may enable better and more complete wind resource assessments for the growing offshore wind sector. Wind lidar technology, and remote sensing in general, has already been proven to be a very promising technology for resource assessment and power performance testing onshore. For offshore applications and on floating platforms in particular, the motions from the floating base have to be considered in addition, affecting the wind measurements significantly and causing systematic measurement errors.We have studied the motions and the corresponding influences on lidar measurements generated by different possible offshore platforms – vessels or buoys – both in detailed simulations as well as first validation experiments. In addition to this, we have developed motion compensation algorithms that allow to correct the affected measurements and retrieve the undisturbed wind data. The motions considered and studied comprise rotations as well as translations in all six degrees of freedom.For the evaluation of the motion-affected and corrected wind data in this paper, special attention is paid to the measurement of turbulence as well as extreme wind events. The research question to be answered is if a lidar device placed on a floating platform is capable of measuring more or less the same statistics of extreme wind events as a fixed lidar device. Quantities to be investigated are: the turbulence intensity as well as the statistics of maximum wind speed values within a 10-min period, but also wind speed increments on different time scales. At this, obviously two issues are to be discussed – the influence of the lidar measurement principle on the recording of extreme wind events, and the additional impact of the superimposed motions of the floating platform.

Effects of two field continuous incremental tests on cardiorespiratory responses in Standardbred trotters.

In humans, cardiorespiratory responses are widely evaluated from field incremental exercise tests. On the contrary, equine exercise physiology faces a huge lack of oxygen consumption measurements (VO2) in field conditions due to technical concerns. The aim of this study was to test the effects of two incremental continuous field tests on cardiorespiratory responses in Standardbred trotters. The two protocols were realized at trot and ended when horses galloped. The tests started at 4.2 m/s (T1) and 6.4 m/s (T2), with speed increments of 1.4 m/s every 3 min for T1 and 0.8 m/s every 2 min for T2. Velocity (v), heart rate (HR) and gas exchanges were recorded continuously, and blood lactate concentration [La(-)] was measured before and after tests. Values recorded at the end of the tests were considered as peak values. The vpeak values were 10.6 ± 0.3 and 10.7 ± 0.7 m/s for T1 and T2 respectively. Horses reached higher VO2peak (T1: 116.6 ± 11.5 ml/min/kg; T2: 88.9 ± 10.2 ml/min/kg; p < 0.05) and HRpeak (T1: 217 ± 5 bpm; T2: 209 ± 3 bpm; p < 0.05) during T1 compared with T2. T1 was significantly longer than T2 (17.5 ± 1.9 vs. 12.9 ± 1.6 min respectively, p < 0.01), and the number of steps entirely ran tended to be different (T1: 5.6 ± 0.6; T2: 6.2 ± 0.8, p = 0.07). Compared to T2, the design of T1 appeared easier to implement and allowed higher cardiorespiratory responses. The relationship between HR-VO2 obtained through T1 gave a better correlation between the two variables than T2. These findings suggest that T1 might be better than T2 for evaluating cardiorespiratory adaptations to exercise and for estimating aerobic energy expenditure in exercising trotters.

Effects of changing speed on knee and ankle joint load during walking and running

Joint moments can be used as an indicator of joint loading and have potential application for sports performance and injury prevention. The effects of changing walking and running speeds on joint moments for the different planes of motion still are debatable. Here, we compared knee and ankle moments during walking and running at different speeds. Data were collected from 11 recreational male runners to determine knee and ankle joint moments during different conditions. Conditions include walking at a comfortable speed (self-selected pacing), fast walking (fastest speed possible), slow running (speed corresponding to 30% slower than running) and running (at 4 m · s−1 ± 10%). A different joint moment pattern was observed between walking and running. We observed a general increase in joint load for sagittal and frontal planes as speed increased, while the effects of speed were not clear in the transverse plane moments. Although differences tend to be more pronounced when gait changed from walking to running, the peak moments, in general, increased when speed increased from comfortable walking to fast walking and from slow running to running mainly in the sagittal and frontal planes. Knee flexion moment was higher in walking than in running due to larger knee extension. Results suggest caution when recommending walking over running in an attempt to reduce knee joint loading. The different effects of speed increments during walking and running should be considered with regard to the prevention of injuries and for rehabilitation purposes.

Shapes and speeds of steady forced premixed flames.

Steady premixed flames subjected to space-periodic steady forcing are studied via inhomogeneous Michelson-Sivashinsky (MS) and then Burgers equations. For both, the flame slope is posited to comprise contributions from complex poles to locate, and from a base-slope profile chosen in three classes (pairs of cotangents, single-sine functions or sums thereof). Base-slope-dependent equations for the pole locations, along with formal expressions for the wrinkling-induced flame-speed increment and the forcing function, are obtained on excluding movable singularities from the latter. Besides exact few-pole cases, integral equations that rule the pole density for large wrinkles are solved analytically. Closed-form flame-slope and forcing-function profiles ensue, along with flame-speed increment vs forcing-intensity curves; numerical checks are provided. The Darrieus-Landau instability mechanism allows MS flame speeds to initially grow with forcing intensity much faster than those of identically forced Burgers fronts; only the fractional difference in speed increments slowly decays at intense forcing, which numerical (spectral) timewise integrations also confirm. Generalizations and open problems are evoked.

Reliability of peak running speeds obtained from different incremental treadmill protocols

This study compared the values and reliability of peak running speeds from incremental treadmill protocols with different speed increments. Thirty-one men, recreational, endurance-trained runners performed, in an alternate order, three continuous tests with different speed increments (0.5, 1 and 2 km · h−1). The tests were repeated using the same order. Peak speed was identified as (1) the greatest speed that could be maintained for a complete minute (Vpeak-60s), (2) the speed of the last complete stage (Vpeak-C) and (3) the speed of the last complete stage added to the product of the speed increment and the completed fraction of the incomplete stage (Vpeak-P). The Vpeak-P was the most reliable, independent of the incremental test protocol (1.5% ≤ CV ≤ 1.8%), and differently from Vpeak-C (1.8% ≤ CV ≤ 2.6%) and Vpeak-60s (1.6% ≤ CV ≤ 3.8%), the Vpeak-P was only slightly influenced by the incremental test protocol. The results suggest that Vpeak-P should be used to assess aerobic capability and monitor training effects and that other determinations of peak speed should be avoided.

Treadmill training and body weight support for walking after stroke.

Treadmill training, with or without body weight support using a harness, is used in rehabilitation and might help to improve walking after stroke. This is an update of a Cochrane review first published in 2005. To determine if treadmill training and body weight support, individually or in combination, improve walking ability, quality of life, activities of daily living, dependency or death, and institutionalisation or death, compared with other physiotherapy gait training interventions after stroke. The secondary objective was to determine the safety and acceptability of this method of gait training. We searched the Cochrane Stroke Group Trials Register (last searched June 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) and the Database of Reviews of Effects (DARE) (The Cochrane Library 2013, Issue 7), MEDLINE (1966 to July 2013), EMBASE (1980 to July 2013), CINAHL (1982 to June 2013), AMED (1985 to July 2013) and SPORTDiscus (1949 to June 2013). We also handsearched relevant conference proceedings and ongoing trials and research registers, screened reference lists and contacted trialists to identify further trials. Randomised or quasi-randomised controlled and cross-over trials of treadmill training and body weight support, individually or in combination, for the treatment of walking after stroke. Two authors independently selected trials, extracted data and assessed methodological quality. The primary outcomes investigated were walking speed, endurance and dependency. We included 44 trials with 2658 participants in this updated review. Overall, the use of treadmill training with body weight support did not increase the chances of walking independently compared with other physiotherapy interventions (risk difference (RD) -0.00, 95% confidence interval (CI) -0.02 to 0.02; P = 0.94; I² = 0%). Overall, the use of treadmill training with body weight support in walking rehabilitation for patients after stroke increased the walking velocity and walking endurance significantly. The pooled mean difference (MD) (random-effects model) for walking velocity was 0.07 m/s (95% CI 0.01 to 0.12; P = 0.02; I² = 57%) and the pooled MD for walking endurance was 26.35 metres (95% CI 2.51 to 50.19; P = 0.03; I² = 60%). Overall, the use of treadmill training with body weight support in walking rehabilitation for patients after stroke did not increase the walking velocity and walking endurance at the end of scheduled follow-up significantly. The pooled MD (random-effects model) for walking velocity was 0.04 m/s (95% CI -0.06 to 0.14; P = 0.40; I² = 40%) and the pooled MD for walking endurance was 32.36 metres (95% CI -3.10 to 67.81; P = 0.07; I² = 63%). However, for ambulatory patients improvements in walking endurance lasted until the end of scheduled follow-up (MD 58.88 metres, 95% CI 29.10 to 88.66; P = 0.0001; I² = 0%). Adverse events and drop outs did not occur more frequently in people receiving treadmill training and these were not judged to be clinically serious events. Overall, people after stroke who receive treadmill training with or without body weight support are not more likely to improve their ability to walk independently compared with people after stroke not receiving treadmill training, but walking speed and walking endurance may improve. Specifically, stroke patients who are able to walk (but not people who are not able to walk) appear to benefit most from this type of intervention. This review found that improvements in walking endurance in people able to walk may have persisting beneficial effects. Further research should specifically investigate the effects of different frequencies, durations or intensities (in terms of speed increments and inclination) of treadmill training, as well as the use of handrails, in ambulatory patients, but not in dependent walkers.

Extreme statistics, Gaussian statistics, and superdiffusion in global magnitude fluctuations in turbulence

Extreme value statistics, or extreme statistics for short, refers to the statistics that characterizes rare events of either unusually high or low intensity: climate disasters like floods following extremely intense rains are among the principal examples. Extreme statistics is also found in fluctuations of global magnitudes in systems in thermal equilibrium, as well as in systems far from equilibrium. A remarkable example in this last class is fluctuations of injected power in confined turbulence. Here we report results in a confined von Kármán swirling flow, produced by two counter-rotating stirrers, in which quantities derived from the same global magnitude—the rotation rate of the stirrers—can display both, extreme and Gaussian statistics. On the one hand, we find that underlying the extreme statistics displayed by the global shear of the flow, there is a nearly Gaussian process resembling a white noise, corresponding to the action of the normal stresses exerted by the turbulent flow, integrated on the flow-driving surfaces of the stirrers. On the other hand, the magnitude displaying Gaussian statistics is the global rotation rate of the fluid, which happens to be a realization of a 1D diffusion where the variance of the angular speed increments ΩR(t + Δt) − ΩR(t) scales as Δtν, while the power spectral density of the angular speed follows a 1/fα scaling law. These scaling exponents are found to be α ≈ 0.37 and ν ≈ 1.36, which implies that this process can be described as a 1D superdiffusion.

Determination of Maximal Oxygen Uptake Using the Bruce or a Novel Athlete-Led Protocol in a Mixed Population

Treadmill tests for maximal oxygen uptake (V̇O2max) have traditionally used set speed and incline increments regardless of participants training or exercise background. The aim of this study was to determine the validity of a novel athlete-led protocol for determining maximal aerobic fitness in adults. Twenty-nine participants (21 male, 8 female, age 29.8 ± 9.5 y, BMI 24.4 ± 3.1, mean ± SD) from a variety of exercise backgrounds were asked to complete two maximal treadmill running tests (using the standard Bruce or a novel athlete-led protocol [ALP]) to volitional failure in a counter-balanced randomised cross-over trial one week apart. We found no substantial difference in maximal oxygen uptake (47.0 ± 9.1 and 46.8 ± 10.7 ml·kg−1·min−1, mean ± SD for the ALP and Bruce protocols respectively), evidenced by the Spearman correlation coefficient of 0.93 (90% confidence limits, 0.88-0.96). However, compared to the Bruce protocol, participants completing the ALP protocol attained a substantially higher maximal heart rate (ALP = 182.8 ± 10.5, Bruce = 179.7 ± 8.7 beats·min−1). Additionally, using the Bruce protocol took a longer period of time (23.2 ± 17.0 s) compared to the ALP protocol. It seems that using either treadmill protocol will give you similar maximal oxygen uptake results. We suggest the ALP protocol which is simpler, quicker and probably better at achieving maximal heart rates is a useful alternative to the traditional Bruce protocol.

Effect of increasing energy cost on arm coordination in elite sprint swimmers

The purpose of this study was to analyze the changes in stroke parameters, motor organization and swimming efficiency with increasing energy cost in aquatic locomotion. Seven elite sprint swimmers performed a 6×300-m incremental swimming test. Stroke parameters (speed, stroke rate and stroke length), motor organization (arm stroke phases and arm coordination index), swimming efficiency (swimming speed squared and hand speed squared) and stroke index were calculated from aerial and underwater side-view cameras. The energy cost of locomotion was assessed by measuring oxygen consumption and blood lactate. Results showed that the increase in energy cost of locomotion was correlated to an increase in the index of coordination and stroke rate, and a decrease in stroke length (p<.05). Furthermore, indicators of swimming efficiency and stroke index did not change significantly with the speed increments (p<.05), indicating that swimmers did not decrease their efficiency despite the increase in energy cost. In parallel, an increase in the index of coordination IdC and stroke rate were observed, along with a decrease in stroke length, stroke index and hand speed squared with each increment, revealing an adaptation to the fatigue within the 300m.

A Bayesian approach for understanding the role of ship speed in whale–ship encounters

Mandatory or voluntary reductions in ship speed are a common management strategy for reducing deleterious encounters between large ships and large whales. This has produced strong resistance from shipping and marine transportation entities, in part because very few studies have empirically demonstrated whether or to what degree ship speed influences ship-whale encounters. Here we present the results of four years of humpback whale sightings made by observers aboard cruise ships in Alaska, representing 380 cruises and 891 ship-whale encounters. Encounters occurred at distances from 21 m to 1000 m (x = 567 m) with 61 encounters (7%) occurring between 200 m and 100 m, and 19 encounters (2%) within 100 m. Encounters were spatially aggregated and highly variable across all ship speeds. Nevertheless a Bayesian change-point model found that the relationship between whale distance and ship speed changed at 11.8 knots (6.1 m/s) with whales encountering ships, on average, 114 m closer when ship speeds were above 11.8 knots. Binning encounter distances by 1-knot speed increments revealed a clear decrease in encounter distance with increasing ship speed over the range of 7-17 knots (3.6-8.7 m/s). Our results are the first to demonstrate that speed influences the encounter distance between large ships and large whales. Assuming that the closer ships come to whales the more likely they are to be struck, our results suggest that reduced ship speed may be an effective management action in reducing the probability of a collision.

Vo2peak Measured During A Ramp Protocol Using Equal Speed Increments Is Highest With Grade

The individualized ramp protocol has shown to induce higher peak oxygen consumption (VO2peak) than standardize stages protocols on treadmill, such as Bruce and Naughton. Previously, it was demonstrated that speed and grade increments invoke a greater VO2peak than speed increments only. However, that study used stages of two minutes, not considered a true ramp protocol, and used different speeds. Therefore, it is not clear if increases exclusive on speed and speed/grade could result on higher VO2peak on a ramp protocol with equal speed increments. PURPOSE: To compare the VO2peak measured during individualized ramp protocol on a treadmill with equal speed increments but different grades (0% and 6%). METHODS: 11 young healthy men (26 ± 5 years, body mass 77.6 ± 9.9, height 176 ± 6 cm, mean ± SD) underwent two sessions of maximal progressive ramp exercise test on treadmill in counterbalanced order. On both tests, increments on speed were equal but grade was kept constant from the beginning (0% and 6%) until voluntary fatigue. Expired gases were continuously collected breath by breath where minute ventilation, VO2, and carbon dioxide output (VCO2) were measured. Additionally we measure blood lactate (La), maximum heart rate (HRmax), rated perceived exertion (RPE) and calculated respiratory exchange ratio (RER). VO2peak was determined by the highest value observed after averaging seven consecutive breaths. Data were analyzed using paired t test. RESULTS: VO2peak was greater on 6% than 0% grade session (50.9 ± 7.6 and 48.2 ± 6.1 ml·Kg-1·min-1, respectively, p=0.03). The total time and final speed were greater on 0% than 6% (11:34 ± 1:40 and 15.4 ± 2.1 versus 8:51 ± 02:09 min and 12.2 ± 1.4 km·h-1, respectively, p<0.001). HRmax (185 ± 7 and 186 ± 7 bpm, respectively, p=0.70), La (9.3 ± 4.4 and 10.3 ± 3.3 mmol·L-1, respectively, p=0.76), RER (1.21 ± 0.06 e 1.22 ± 0.05 respectively p=0.90), and VE (149.0 ± 30.8 e 153.0 ± 32.4 L·min-1 respectively p=0.26) were not different between 0% and 6%. CONCLUSION: We conclude that VO2peak, measured during ramp protocol, is higher when the grade is present. We speculate that auxiliary and accessory muscles' participation increases oxygen consumption. Additionally, the difficulty to maintain high speeds on no grade tests may limit higher VO2peak achievement.

Normative Cardiorespiratory Fitness Data for Cancer Survivors and Development of a Cancer-Specific Treadmill Protocol

PURPOSE: To establish a set of cancer-specific cardiopulmonary normative data as an index which cancer exercise specialists can use to reasonably evaluate their clients. Additionally, to develop a treadmill protocol more suited for this population. METHODS: Five hundred forty three subjects' data were analyzed for this study, 79% of which were female. All subjects were clients at the Rocky Mountain Cancer Rehabilitation Institute (RMCRI). Quintiles were constructed for VO2 peak and Bruce treadmill protocol time to exhaustion for females, males, and all clients. Additionally, normative values for five separate age groups were determined. Based upon the normative values of VO2 peak and treadmill time, and considering the physical limitations of the cancer population at RMCRI, a new treadmill protocol was formulated. RESULTS: For the Bruce protocol, only individuals in the highest quintile lasted more than 8:08 or had a VO2 peak greater than 26.8 mL/kg/min and the middle quintile ranged from 5:00 - 6:30 and 19.5 - 23 mL/kg/min, respectively. In all but one of the ten age and gender groups, the cutoff value for the highest quintile of cancer survivors' VO2 values fell within the "poor" classification when using norms for apparently healthy individuals. Compared to the Bruce protocol, the RMCRI treadmill protocol has shorter stages, with small speed and grade increments every minute. Clients were able to reach higher predicted VO2 values and reported aerobic fitness as the limiting factor of exercise rather than peripheral fatigue. CONCLUSION: The low VO2 peak values reported in RMCRI clients is a reflection of both low fitness and underestimation of VO2 due to peripheral fatigue associated with an inappropriate testing protocol for the cancer population. The RMCRI protocol maintains both reasonable grade and speed over a large range, which is important in a cancer rehabilitation setting, where clients' fitness and general health status vary considerably.

Walking Economy of Adults with Down Syndrome

This study intended to investigate walking economy (WE) in response to different treadmill speeds and grades in adults with Down syndrome (DS) and in non-disabled controls. Eighteen participants (14 males; 4 females) with DS (33.6+/-7.6 years) and 16 non-disabled (12 males, 4 females) controls (33.3+/-8.0 years) performed submaximal (2.5 km . h (-1) and 4 km . h (-1) at 0% grade; 4 km . h (-1) at 2.5% and 5% grade, for 5 min each) and maximal treadmill tests with metabolic and heart rate measurements. Oxygen uptake (VO(2)) was not different between groups at rest or during the slowest treadmill speed. However, at faster speeds and increased grades, adults with DS presented lower WE than controls (p<0.0001). Subsequent analyses revealed that, despite showing higher delta VO(2) response to the selected speed increments (p<0.0001), individuals with DS produced similar VO(2) increase as controls to grade variations. Therefore, adults with DS exhibit lower WE than non-disabled controls at a speed faster than their preferred walking speed. Additionally, in comparison to controls, individuals with DS show a greater change in energy expenditure with a change in walking speed. In conclusion, lower WE in individuals with DS is mainly related to their inability to adapt efficiently to positive variations in walking speed.

Characterization of short time fluctuations in atmospheric wind speeds by LIDAR measurements

Wind velocity measurements were taken using a Leosphere Windcube LIDAR system, which operates as a pulsed laser Doppler anemometer. Here we report on first results, which show typical characteristics of atmospheric wind velocities. Especially pronounced intermittent (or heavy-tailed) probability density functions (PDF) of wind speed increments are present on all observed time scales. A transition for large time scales towards a more Gaussian shape is found if only ten minute intervals are selected which share the same mean wind speed. Both typical shapes of PDF are well described and modeled by two previously proposed models.

Functional resources to increase gait speed in people with stroke: Strategies adopted compared to healthy controls

Thirty-nine adult individuals with stroke in the stable phase were asked to walk at their preferred speed and then as fast as possible. A set of gait indexes were computed, including spatial temporal parameters, ankle and hip mechanical work, and timing of ankle push-off onset, for comparison with normal velocity-dependent profiles. Algorithms were used to classify the resulting gait patterns when the patients walked at their preferred speed and fast and to identify the patients’ strategies to maximise speed. Patients’ strategies were characterised by a variation in the parameters, which were reduced, equal or increased, in relation to normal patterns. At both speeds, stroke individuals tended to walk at higher cadence and with shorter stride length. At the preferred speed the investigated parameters for all patients were mostly within the normal profile (71.8–94.9%). The exception was the finding of positive work at the ankle where 64% of the stroke individuals showed reduced work production. At fast speed (increments to 36%BH/s) fewer patients presented values within the normal profile for all the parameters (17.9–74.4%), with the exception of negative work at the ankle and hip. The parameter variations showed a more consistently abnormal picture. The results indicate that, in order to increase gait speed, patients with hemiparesis have different functional resources on which to draw, and these vary from individual to individual. Thus, gait analysis at different gait speed should be adopted to develop individualised programs that will improve quality of life for the patients.

Comparison of maximal and spontaneous speeds during walking on dry land and water

The aim of this study was to quantify spontaneous and maximal speeds on dry land and in water, in four modalities of walking [forward (F), backward (B) and lateral walking (L)], with chest immersion level. Lateral walking was studied with the upper limbs of the subject alongside the body with hands placed on the lateral face of the thighs (L1) and upper limbs tightened behind the back with the hands joined (L2). 16 males (age 22.8 ± 1.8 years, height 178.1 ± 6.1 cm, body mass 73.5 ± 6.6 kg) and 15 females (age 22.8 ± 2.1 years, height 171.5 ± 5.8 cm, body mass 69.2 ± 9.3 kg) were evaluated using the four modalities of walking on dry land and in water. The speed increments between spontaneous and maximal speeds on dry land for F, B and L1 and L2 were 60.2%, 60.9%, 64.3% and 65.3% for males and 47.3%, 48.3%, 44.5% and 53.1% for females. In the water, these variation values for F, B, L1 and L2 for males were 44.6%, 26.1%, 48.8%, and 42.1%. The values for females were 31.7%, 21.6%, 32.8%, and 34.6%. Spontaneous and maximal speeds of walking were substantially reduced in water with the chest immersed, compared to speeds on dry land for the four modalities and the two genders. These findings may be used by therapists who utilize the various modalities of walking in aquatherapy.