290,283 research outputs found
Exercise intensity-dependent effects of arm and leg-cycling on cognitive performance
Physiological responses to arm and leg-cycling are different, which may influence psychological and biological mechanisms that influence post-exercise cognitive performance. The aim of this study was to determine the effects of maximal and submaximal (absolute and relative intensity matched) arm and leg-cycling on executive function. Thirteen males (age, 24.7 ± 5.0 years) initially undertook two incremental exercise tests to volitional exhaustion for arm-cycling (82 ± 18 W) and leg-cycling (243 ± 52 W) for the determination of maximal power output. Participants subsequently performed three 20-min constant load exercise trials: (1) arm-cycling at 50% of the ergometer-specific maximal power output (41 ± 9 W), (2) leg-cycling at 50% of the ergometer-specific maximal power output (122 ± 26 W), and (3) leg-cycling at the same absolute power output as the submaximal arm-cycling trial (41 ± 9 W). An executive function task was completed before, immediately after and 15-min after each exercise test. Exhaustive leg-cycling increased reaction time (p 0.05). Improvements in reaction time following arm-cycling were maintained for at least 15-min post exercise (p = 0.008, d = -0.73). Arm and leg-cycling performed at the same relative intensity elicit comparable improvements in cognitive performance. These findings suggest that individuals restricted to arm exercise possess a similar capacity to elicit an exercise-induced cognitive performance benefit
Physiological correlates of simulated sprint-distance triathlon
The purpose of this study was to examine the relationship between simulated triathlon performance and physiological variables measured during conventional laboratory tests. Seven non-elite, competitive male triathletes completed incremental cycling and running tests in a random order, in addition to a simulated sprint-distance triathlon trial (750 m swim, 500 kJ bike, 5 km run) using a 25 m pool, an electromagnetically braked cycle ergometer and motorised treadmill. There were no significant correlations between overall performance time and either running or cycling incremental tests, however significant correlations were found between triathlon run time and both running and cycling incremental tests (Vpeak, r = -.900, p<0.05; V4mmol, r = -.822, p<0.05; Wpeak, r = -.844, p<0.05). Total simulated triathlon time was highly correlated to cycle time (r = .930, p<0.05) and mean cycling power output (r = -.956, p<0.05), whilst there was no significant correlation between either swim time or run time and overall performance time. For non-elite, competitive male triathletes, a performance assessment which better reflects the demands of the cycle phase of triathlon (i.e. a time-trial protocol) may provide a better indication of simulated sprint-distance triathlon performance in comparison to commonly used incremental laboratory tests. Furthermore, cycling performance appears more important to overall performance in simulated sprint-distance triathlon than swimming or running
Separator for alkaline batteries
Separator compositions have been tested as components of three-plate silver-zinc oxide cells in a standard cycling test. Six materials meet imposed requirements, giving cycling performance superior to cellophane
Inspiratory muscle warm-up does not improve cycling time-trial performance
Purpose: This study examined the effects of an active cycling warm-up, with and without the addition of an inspiratory muscle warm-up (IMW), on 10-km cycling time-trial performance
Pragmatic Low-Power Interoperability: ContikiMAC vs TinyOS LPL
Standardization has driven interoperability at multiple layers of the stack, such as the routing and application layers, standardization of radio duty cycling mechanisms have not yet reached the same maturity. In this work, we pitch the two de facto standard flavors of sender-initiated radio duty cycling mechanisms against each other: ContikiMAC and TinyOS LPL. Our aim is to explore pragmatic interoperability mechanisms at the radio duty cycling layer. This will lead to better understanding of interoperability problems moving forward, as radio duty cycling mechanisms get standardized. Our results show that the two flavors can be configured to operate together but that parameter configuration may severely hurt performance
Control strategies for integration of electric motor assist and functional electrical stimulation in paraplegic cycling: Utility for exercise testing and mobile cycling
AIM: The aim of this study was to investigate feedback
control strategies for integration of electric motor assist and functional electrical stimulation (FES) for paraplegic cycling, with particular focus on development of a testbed for exercise testing in FES cycling, in which both cycling cadence and workrate are simultaneously well controlled and contemporary physiological measures of exercise performance derived. A second aim was
to investigate the possible benefits of the approach for mobile, recreational cycling.
METHODS: A recumbent tricycle with an auxiliary electric motor is used, which is adapted for paraplegic users, and instrumented for stimulation control. We propose a novel integrated control strategy which simultaneously provides feedback control of leg power output (via automatic adjustment of stimulation intensity) and cycling cadence (via electric motor control). Both loops are
designed using system identification and analytical (model-based) feedback design methods. Ventilatory and pulmonary gas exchange response profiles are derived using a portable system for real-time breath-by-breath acquisition.
RESULTS:We provide indicative results from one paraplegic subject in which a series of feedback-control tests illustrate accurate control of cycling cadence, leg power control, and external disturbance rejection. We also provide physiological response profiles from a submaximal exercise step test and a maximal incremental exercise test, as facilitated by the control strategy.
CONCLUSION: The integrated control strategy is effective in facilitating
exercise testing under conditions of well-controlled cadence
and power output. Our control approach significantly extends the
achievable workrate range and enhances exercise-test sensitivity
for FES cycling, thus allowing a more stringent characterization
of physiological response profiles and estimation of key parameters
of aerobic function.We further conclude that the control approach
can significantly improve the overall performance of mobile recreational
cycling
The Effects of Mild Dehydration on Cycling Performance in the Heat
Abstract
Introduction: Hypohydration exceeding 2% of body mass (bm), affected by heat and thirst level, leads to decreased athletic performance. Both physiological and psychological factors of dehydration have an impact on an athlete’s perceived performance. However, it is unclear whether the effects of psychological, physiological, or both have a negative impact on athletic performance caused by mild hypohydration. Purpose: The purpose of this study was to determine if mild hypohydration affects exercise performance in trained cyclists while blinding their hydration state. Methodology: Eleven competitive male cyclists participated in two blinded experimental trials, hypohydrated and euhydrated states by intra-venous infusions. The experimental criterium simulation test includes cycling through 3 sets of 20-minute steady state followed by a 5km race. Results: During the 5km time trial, the hypohydrated trial (39.0±0.5°C) resulted in significantly higher core temperatures compared to the euhydrated trial (38.5±0.2°C; P\u3c0.05). Cycling speed was significantly faster in the euhydrated vs. the hypohydrated trial (27.3±0.1 vs. 26.2±0.7 km×h-1; P\u3c0.05) due to greater cycling power output (304±6 vs. 286±10 W; P\u3c0.05). Conclusion: Overall, the study found that mild hypohydration led to impairment in exercise performance in the heat compared to euhydration, when subjects were unaware of their hydration state. These responses might have been a response of great heat strain and/or cardiovascular impairment
Secondary zinc-oxygen cell for spacecraft applications Quarterly report, 23 Sep. - 23 Dec. 1967
Cycling performance of secondary zinc oxygen cell for spacecraf
Spacecraft adhesives for long life and extreme environments
High temperature cycling tests of high performance adhesives for aerospace application
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