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The purpose of this study was to assess the accuracy of the Cosmed K5 portable metabolic system dynamic mixing chamber (MC) and breath-by-breath (BxB) modes against the criterion Douglas bag (DB) method. Fifteen participants (mean age±SD, 30.6±7.4 yrs) had their metabolic variables measured at rest and during cycling at 50, 100, 150, 200, and 250W. During each stage, participants were connected to the first respiratory gas collection method (randomized) for the first four minutes to reach steady state, followed by 3-min (or 5-min for DB) collection periods for the resting condition, and 2-min collection periods for all cycling intensities. Collection periods for the second and third methods were preceded by a washout of 1-3 min. Repeated measures ANOVAs were used to compare metabolic variables measured by each method, for seated rest and each cycling work rate. For ventilation (VE) and oxygen uptake (VO2), the K5 MC and BxB modes were within 2.1 l/min (VE) and 0.08 l/min (VO2) of the DB (p≥0.05). Compared to DB values, carbon dioxide production (VCO2) was significantly underestimated by the K5 BxB mode at work rates ≥150W by 0.12-0.31 l/min (p<0.05). K5 MC and BxB respiratory exchange ratio values were significantly lower than DB at cycling work rates ≥100W by 0.03-0.08 (p<0.05). Compared to the DB method, the K5 MC and BxB modes are acceptable for measuring VE and VO2 across a wide range of cycling intensities. Both K5 modes provided comparable values to each other.

Numerous accelerometers and prediction methods are used to estimate energy expenditure (EE). Validation studies have been limited to small sample sizes in which participants complete a narrow range of activities and typically validate only one or two prediction models for one particular accelerometer. The purpose of this study was to evaluate the validity of nine published and two proprietary EE prediction equations for three different accelerometers. Two hundred and seventy-seven participants completed an average of six treadmill (TRD) (1.34, 1.56, 2.23 ms −1 each at 0 and 3% grade) and five self-paced activities of daily living (ADLs). EE estimates were compared with indirect calorimetry. Accelerometers were worn while EE was measured using a portable metabolic unit. To estimate EE, 4 ActiGraph prediction models were used, 5 Actical models, and 2 RT3 proprietary models. Across all activities, each equation underestimated EE (bias −0.1 to −1.4 METs and −0.5 to −1.3 kcal, respectively). For ADLs EE was underestimated by all prediction models (bias −0.2 to −2.0 and −0.2 to −2.8, respectively), while TRD activities were underestimated by seven equations, and overestimated by four equations (bias −0.8 to 0.2 METs and −0.4 to 0.5 kcal, respectively). Misclassification rates ranged from 21.7 (95% CI 20.4, 24.2%) to 34.3% (95% CI 32.3, 36.3%), with vigorous intensity activities being most often misclassified. Prediction equations did not yield accurate point estimates of EE across a broad range of activities nor were they accurate at classifying activities across a range of intensities (light <3 METs, moderate 3–5.99 METs, vigorous ≥6 METs). Current prediction techniques have many limitations when translating accelerometer counts to EE.

Objective: To compare the effects of body weight-supported treadmill training and overground walking training when matched for task and dose (duration/frequency/intensity) on improving walking function, activity, and participation after stroke. Design: Single-blind, pilot randomized controlled trial with three-month follow-up. Settings: University and community settings. Subjects: A convenience sample of participants (N = 20) at least six months post-stroke and able to walk independently were recruited. Interventions: Thirty-minute walking interventions (body weight-supported treadmill training or overground walking training) were administered five times a week for two weeks. Intensity was monitored with the Borg Rating of Perceived Exertion Scale at five-minute increments to maintain a moderate training intensity. Main Measures: Walking speed (comfortable/fast 10-meter walk), walking endurance (6-minute walk), spatiotemporal symmetry, and the ICF Measure of Participation and ACTivity were assessed before, immediately after, and three months following the intervention. Results: The overground walking training group demonstrated significantly greater improvements in comfortable walking speed compared with the body weight-supported treadmill training group immediately (change of 0.11 m/s vs. 0.06 m/s, respectively; p = 0.047) and three months (change of 0.14 m/s vs. 0.08 m/s, respectively; p = 0.029) after training. Only the overground walking training group significantly improved comfortable walking speed (p = 0.001), aspects of gait symmetry (p = 0.032), and activity (p = 0.003) immediately after training. Gains were maintained at the three-month follow-up (p < 0.05) for all measures except activity. Improvements in participation were not demonstrated. Conclusion: Overgound walking training was more beneficial than body weight-supported treadmill training at improving self-selected walking speed for the participants in this study.

To compare physiological and perceptual response of running on a curved non-motorized treadmill (cNMT) with running on a motorized treadmill (MT), and to determine the running velocity at which a physiological response≥90% V˙O2max was elicited. 13 trained male runners (mean±SD; 36±11years, 1.80±0.06m, 70±4kg, V˙O2max: 57.3±3.5 mLkg−1min−1) performed an incremental running test on a MT to determine V˙O2max and the accompanying maximum velocity (Vmax). Participants first completed a familiarization session on the cNMT. Next, participants ran for 4min at five/six progressively higher velocities (40–90% Vmax). These runs were completed on the cNMT and MT in two separate visits in a randomized and counterbalanced order. No participant was able to complete the 4min run at 80% Vmax on the cNMT. Running on the cNMT elicit a higher relative oxygen uptake (%V˙O2max) across all velocities compared to the MT (32.5±5%, p<0.001, ES 3.3±0.9), and was accompanied by significantly higher heart rates (16.8±3%, p<0.001, ES 3.4±1.5), an altered cadence (2.6±0.7%, p<0.001, ES 0.8±0.3) and ratings of perceived exertion (27.2±5%, p<0.001, ES 2.3±0.6). A less efficient running economy was evident when running on the cNMT (+38.4±16%, p<0.001, ES 2.73). Individual (n=9) linear interpolation predicted an exercise intensity of 90% V˙O2max was achieved in the non-motorized condition when running at 62.1±3.5% Vmax (R2=0.986±0.01), which was lower than MT run in which 90% V˙O2max was achieved at 81.4±5.6% Vmax (R2=0.985±0.02; 29.8±8%, p<0.001, ES 3.87). Running on the cNMT has higher physiological and perceptual demands and increases cadence.

We investigated the differences in performance between 100-m sprints performed on a sprint treadmill recently validated versus on a standard track. To date, studies comparing overground and treadmill running have mainly focused on constant and not maximal “free” running speed, and compared running kinetics and kinematics over a limited number of steps, but not overall sprint performance. Eleven male physical education students including two sprinters performed one 100-m on the treadmill and one on a standard athletics track in a randomized order, separated by 30 min. Performance data were derived in both cases from speed–time relationships measured with a radar and with the instrumented sprint treadmill, which allowed subjects to run and produce speed “freely”, i.e. with no predetermined belt speed imposed. Field and treadmill typical speed–distance curves and data of maximal and mean speed, 100-m time and acceleration/deceleration time constants were compared using t tests and field–treadmill correlations were tested. All the performance parameters but time to reach top speed and deceleration time constant differed significantly, by about 20% on average, between field and treadmill (e.g. top speed of 8.84 ± 0.51 vs. 6.90 ± 0.39 m s −1 ). However, significant correlations were found ( r  > 0.63; P  < 0.05) for all the performance parameters except time to reach top speed. Treadmill and field 100-m sprint performances are different, despite the fact that subjects could freely accelerate the belt. However, the significant correlations found make it possible to investigate and interpret inter-individual differences in field performance from treadmill measurements.

Purpose To investigate whether a metabolic cart using a flowmeter in the upper range of accepted resistance to airflow (<1.5 cmH2O∙L−1∙s−1 for flows up to 14 L∙s−1, American Thoracic Society) negatively impacts exercise performance in healthy individuals. Methods 16 recreationally active males (age 25 ± 1 years, height 180 ± 6 cm, weight 73.5 ± 5.8 kg, all mean ± SD) performed two incremental tests on a bicycle ergometer on each of two visits, using a metabolic cart with a flowmeter of either low (Oxycon Pro) or high (Innocor) airflow resistance. Mouth pressures, gas exchange, blood lactate concentration [La−], perception of breathlessness, respiratory, and leg exertion were assessed throughout the tests. Results Tests performed with the Innocor were significantly shorter (15.3 ± 3.2 vs. 15.8 ± 3.3 min, p < 0.0001) and showed higher maximal flow resistance (1.3 ± 0.2 vs. 0.3 ± 0.0 cmH2O∙L−1∙s−1, p < 0.0001). At end‐exercise, peak oxygen consumption (−200 ± 220 ml.min−1, p < 0.0001), minute ventilation (−19.9 ± 10.5 L.min−1, p < 0.0001), breathing frequency (−5.4 ± 5.2 breaths.min−1, p < 0.0001), heart rate (−2.1 ± 3.6 bpm, p = 0.002) and [La−] (−0.7 ± 1.0 mmol.L−1, p < 0.0001), but not tidal volume (−0.1 ± 0.2 L, p = 0.172) were lower with the Innocor, while the perception of breathlessness was higher (+3.8 ± 5.1 points, p < 0.0001). Conclusions Airflow resistance in the upper range of current guidelines can significantly affect exercise performance and respiratory pattern in young, healthy males during incremental exercise. The present results indicate the need to revisit guidelines for devices used in ergospirometry. Current guidelines allow for respiratory resistance up to 1.5 cmH2 = L/s in metabolic carts. We demonstrate that equipment operating in the upper limit of this range negatively affect exercise performance. Current guidelines should be re‐considered.

Aim  To compare the effects of a supported speed treadmill training exercise program (SSTTEP) with exercise on spasticity, strength, motor control, gait spatiotemporal parameters, gross motor skills, and physical function. Method  Twenty‐six children (14 males, 12 females; mean age 9y 6mo, SD 2y 2mo) with spastic cerebral palsy (CP; diplegia, n=12; triplegia, n=2; quadriplegia n=12; Gross Motor Function Classification System levels II–IV) were randomly assigned to the SSTTEP or exercise (strengthening) group. After a twice daily, 2‐week induction, children continued the intervention at home 5 days a week for 10 weeks. Data collected at baseline, after 12‐weeks’ intervention, and 4 weeks after the intervention stopped included spasticity, motor control, and strength; gait spatiotemporal parameters; Gross Motor Function Measure (GMFM); and Pediatric Outcomes Data Collection Instrument (PODCI). Results  Gait speed, cadence, and PODCI global scores improved, with no difference between groups. No significant changes were seen in spasticity, strength, motor control, GMFM scores, or PODCI transfers and mobility. Post‐hoc testing showed that gains in gait speed and PODCI global scores were maintained in the SSTTEP group after withdrawal of the intervention. Interpretation  Although our hypothesis that the SSTTEP group would have better outcomes was not supported, results are encouraging as children in both groups showed changes in function and gait. Only the SSTTEP group maintained gains after withdrawal of intervention.

Assessment of peak oxygen consumption (Vo(2)peak) using traditional modes of testing such as treadmill or cycle ergometer can be difficult in individuals with stroke due to balance deficits, gait impairments, or decreased coordination. The purpose of this study was to quantitatively assess the validity and feasibility of a modified exercise test using a total-body recumbent stepper (mTBRS-XT) in individuals after stroke. A within-subject design, with a sample of convenience, was used. Eleven participants (7 male, 4 female) with a mean of 40.1 months (SD=32.7) after stroke, a mean age of 60.9 years (SD=12.0), and mild to severe lower-extremity Fugl-Myer test scores (range=13-34) completed the study. Participants performed 2 maximal-effort graded exercise tests on separate days using the mTBRS-XT and a cycle ergometer exercise protocol to assess cardiorespiratory fitness. Measurements of Vo(2)peak and peak heart rate (peak HR) were obtained during both tests. A strong relationship existed between the mTBRS-XT and the cycle ergometer exercise test for Vo(2)peak and peak HR (r=.91 and .89, respectively). Mean Vo(2)peak was significantly higher for the mTBRS-XT (16.6 mL x kg(-1) x min(-1)[SD=4.5]) compared with the cycle ergometer exercise protocol (15.4 mL x kg(-1) x min(-1) [SD=4.5]). All participants performed the mTBRS-XT. One individual with severe stroke was unable to pedal the cycle ergometer. No significant adverse events occurred. The mTBRS-XT may be a safe, feasible, and valid exercise test to obtain measurements of Vo(2)peak in people with stroke. Health care professionals may use the mTBRS-XT to prescribe aerobic exercise based on Vo(2)peak values for individuals with mild to severe deficits after stroke.

Background Walking requires gait adjustments in order to walk safely in continually changing environments. Gait adaptability is reduced in older adults, and (near) falls, fall-related hip fractures and fear of falling are common in this population. Most falls occur due to inaccurate foot placement relative to environmental hazards, such as obstacles. The C-Mill is an innovative, instrumented treadmill on which visual context (e.g., obstacles) is projected. The C-Mill is well suited to train foot positioning relative to environmental properties while concurrently utilizing the high-intensity practice benefits associated with conventional treadmill training. The present protocol was designed to examine the efficacy of C-Mill gait adaptability treadmill training for improving walking ability and reducing fall incidence and fear of falling relative to conventional treadmill training and usual care. We hypothesize that C-Mill gait adaptability treadmill training and conventional treadmill training result in better walking ability than usual care due to the enhanced training intensity, with superior effects for C-Mill gait adaptability treadmill training on gait adaptability aspects of walking given the concurrent focus on practicing step adjustments. Methods/design The protocol describes a parallel group, single-blind, superiority randomized controlled trial with pre-tests, post-tests, retention-tests and follow-up. Hundred-twenty-six older adults with a recent fall-related hip fracture will be recruited from inpatient rehabilitation care and allocated to six weeks of C-Mill gait adaptability treadmill training (high-intensity, adaptive stepping), conventional treadmill training (high-intensity, repetitive stepping) or usual care physical therapy using block randomization, with allocation concealment by opaque sequentially numbered envelopes. Only data collectors are blind to group allocation. Study parameters related to walking ability will be assessed as primary outcome pre-training, post-training, after 4 weeks retention and 12 months follow-up. Secondary study parameters are measures related to fall incidence, fear of falling and general health. Discussion The study will shed light on the relative importance of adaptive versus repetitive stepping and practice intensity for effective intervention programs directed at improving walking ability and reducing fall risk and fear of falling in older adults with a recent fall-related hip fracture, which may help reduce future fall-related health-care costs. Trial registration The Netherlands Trial Register ( http://NTR3222 ).

The aim of the present study was to gain better insight into the mechanisms underpinning the sigmoid pattern of deoxy[Hb + Mb] during incremental exercise by assessing the changes in the profile following prior high-intensity exercise. Ten physically active students performed two incremental ramp (25 W min −1 ) exercises (AL and LL, respectively) preceded on one occasion by incremental arm (10 W min −1 ) and on another occasion by incremental leg exercise (25 W min −1 ), which served as the reference test (RT). Deoxy[Hb + Mb] was measured by means of near-infrared spectroscopy and surface EMG was recorded at the Vastus Lateralis throughout the exercises. Deoxy[Hb + Mb], integrated EMG and Median Power Frequency (MdPF) were expressed as a function of work rate (W) and compared between the exercises. During RT and AL deoxy[Hb + Mb] followed a sigmoid increase as a function of work rate. However, during LL deoxy[Hb + Mb] increased immediately from the onset of the ramp exercise and thus no longer followed a sigmoid pattern. This different pattern in deoxy[Hb + Mb] was accompanied by a steeper slope of the iEMG/ W -relationship below the GET (LL: 0.89 ± 0.11% W −1 ; RT: 0.74 ± 0.08% W −1 ; AL: 0.72 ± 0.10% W −1 ) and a more pronounced decrease in MdPF in LL (17.2 ± 4.5%) compared to RT (5.0 ± 2.1%) and AL (3.9 ± 3.2%). It was observed that the sigmoid pattern of deoxy[Hb + Mb] was disturbed when the ramp exercise was preceded by priming leg exercise. Since the differences in deoxy[Hb + Mb] were accompanied by differences in EMG it can be suggested that muscle fibre recruitment is an important underlying mechanism for the pattern of deoxy[Hb + Mb] during ramp exercise.