A Comparison of Critical Velocity Estimates to Actual Velocities in Predicting Simulated Rowing Performance

As 180-degree meanders are observed in abundance in nature, a meandering channel with two consecutive 180-degree bends was designed and constructed to investigate bed topography variations. These two 180-degree mild bends are located between two upstream and downstream straight paths. In this study, different mean velocity-to-critical velocity ratios have been tested at the upstream straight path to determine the meander’s incipient motion. To this end, bed topography variations along the meander and the downstream straight path were addressed for different mean velocity-to-critical velocity ratios. In addition, the upstream bend’s effect on the downstream bend was investigated. Results indicated that the maximum scour depth at the downstream bend increased as a result of changing the mean velocity-to-critical velocity ratio from 0.8 to 0.84, 0.86, 0.89, 0.92, 0.95, and 0.98 by, respectively, 1.5, 2.5, 5, 10, 12, and 26 times. Moreover, increasing the ratio increased the maximum sedimentary height by 3, 10, 23, 48, 49, and 56 times. The upstream bend’s incipient motion was observed for the mean velocity-to-critical velocity ratio of 0.89, while the downstream bend’s incipient motion occurred for the ratio of 0.78.

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RELATIONSHIP BETWEEN THE LEVEL OF EDUCATION AND FUNCTIONAL CAPACITY IN ACTIVE ELDERLY ADULTS

Journal of Frailty & Aging ◽

10.14283/jfa.2014.16 ◽

2014 ◽

pp. 1-5

Author(s):

M.-M. DUBUC ◽

S. BARBAT-ARTIGAS ◽

A.D. KARELIS ◽

M. AUBERTIN-LEHEUDRE

Keyword(s):

Oxygen Consumption ◽

Functional Capacity ◽

Maximal Oxygen Consumption ◽

The Elderly ◽

Knee Extensors ◽

Elderly Adults ◽

Timed Up And Go ◽

Level Of Education ◽

Sf 36 ◽

The Relationship

Background:Both the level of education and functional capacity seems to be associated with the levelof physical activity in the elderly. However, the relationship between the level of education and functionalcapacity in active elderly adults is poorly understood. Objective:To examine the association between the level ofeducation and the functional capacity profile of active elderly adults. Design:Cross-sectional. Participants:Onehundred and four elderly men and 198 postmenauposal women (mean age: 62.7 ± 7.6 years old) were recruitedamong registered members of the YMCAs of Montreal who practiced at least one hour of structured physicalactivity per week. Participants were then divided in two groups based on their level of education (the cut-offpoint was the high-school diploma). Measurements:Body composition (DXA), muscle strength (knee extensors,handgrip), estimated maximal oxygen consumption (2-km walk test), perceived health (SF-36) and functionalcapacity (timed up and go, alternate step and one-leg stance tests) were measured. The level of education of theparticipants was assessed by questionnaire. Results:Body composition was similar between groups. We observedthat all functional capacity tests as well as the global functional capacity score were significantly higher in themost educated group compared to the least educated group (p<0.05). In addition, the most educated group hadsignificantly higher levels of knee extensors strength, estimated maximal oxygen consumption and perception ofphysical functioning. Conclusions:A higher level of education was associated with a favourable functionalcapacity profile in our cohort of active elderly adults. However, the mechanism(s) which could mediate thisassociation remain(s) unknown.

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Plasma free and sulfoconjugated catecholamine responses to varying exercise intensity

Journal of Applied Physiology ◽

10.1152/jappl.1987.63.2.654 ◽

1987 ◽

Vol 63 (2) ◽

pp. 654-658 ◽

Cited By ~ 19

Author(s):

M. S. Sothmann ◽

A. B. Gustafson ◽

M. Chandler

Keyword(s):

Oxygen Consumption ◽

Exercise Intensity ◽

High Intensity ◽

Maximal Oxygen Consumption ◽

High Intensity Exercise ◽

The Relationship ◽

Circulating Levels

Plasma free catecholamines rise during exercise, but sulfoconjugated catecholamines reportedly fall. This study examined the relationship between exercise intensity and circulating levels of sulfoconjugated norepinephrine, epinephrine, and dopamine. Seven exercise-trained men biked at approximately 30, 60, and 90% of their individual maximal oxygen consumption (VO2max) for 8 min. The 90% VO2max period resulted in significantly increased plasma free norepinephrine (rest, 219 +/- 85; exercise, 2,738 +/- 1,149 pg/ml; P less than or equal to 0.01) and epinephrine (rest, 49 +/- 49; exercise, 555 +/- 516 pg/ml; P less than or equal to 0.05). These changes were accompanied by consistent increases in sulfoconjugated norepinephrine at both the 60% (rest, 852 +/- 292; exercise, 1,431 +/- 639; P less than or equal to 0.05) and 90% (rest, 859 +/- 311; exercise, 2,223 +/- 1,015; P less than or equal to 0.05) VO2max periods. Plasma sulfoconjugated epinephrine and dopamine displayed erratic changes at the three exercise intensities. These findings suggest that sulfoconjugated norepinephrine rises during high-intensity exercise.

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Measurements and numerical simulations of snow-particle saltation

Annals of Glaciology ◽

10.3189/1998aog26-1-184-190 ◽

1998 ◽

Vol 26 ◽

pp. 184-190 ◽

Cited By ~ 5

Author(s):

K. Nishimura ◽

K. Sugiura ◽

M. Nemoto ◽

N. Maeno

Keyword(s):

Friction Velocity ◽

Laser Sheet ◽

Impact Angle ◽

Wind Tunnel Experiments ◽

Mean Velocity ◽

Measured Probability ◽

The Mean ◽

Snow Particle ◽

The Relationship ◽

Particle Saltation

First, wind-tunnel experiments were carried out to measure the trajectories of saltating snow particles with varying friction velocity. Trajectories of saltating particles were recorded by a video system with a laser sheet and trajectory statistics, such as ejection and impact velocities and angles, were obtained for each particle. Parabolic trajectories are considerably elongated with an increase in the friction velocity; impact angle was approximately the same but ejection angle decreased with increasing friction velocity. Furthermore, it should be noted that the gradient of flux decay with height decreased with friction velocity. In the experiments, a snow-particle counter, which can sense not only the number of particles but also their diameters, was introduced. The flux distribution and the transport rate obtained as a function of the particle size gave a new insight into the relationship with the friction velocity.Trajectories of saltating grains were computed, using the measurements of the initial ejection velocities, angles and the mean velocity profile of the air. The results agreed reasonably with our measurements. Using the measured probability distribution of the ejection velocities, an ensemble of trajectories was computed and thence the vertical profiles of stream-wise fluxes. The exponential decay of the flux on height was obtained in all cases and it supports the basic validity of the model, although agreement is less than expected.

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Physical training and heart rate and blood pressure variability: a 5-yr randomized trial

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00600.2003 ◽

2004 ◽

Vol 286 (5) ◽

pp. H1821-H1826 ◽

Cited By ~ 34

Author(s):

Arja L. T. Uusitalo ◽

Tomi Laitinen ◽

Sari B. Väisänen ◽

Esko Länsimies ◽

Rainer Rauramaa

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Oxygen Consumption ◽

Blood Pressure Variability ◽

Maximal Oxygen Consumption ◽

Final Analysis ◽

Peak Performance ◽

Autonomic Modulation ◽

The Mean ◽

Time Point

We studied the effect of regular physical activity on cardiac and vascular autonomic modulation during a 5-yr controlled randomized training intervention in a representative sample of older Finnish men. Heart rate variability (HRV) and blood pressure variability (BPV) are markers of cardiac and vascular health, reflecting cardiac and vascular autonomic modulation. One hundred and forty randomly selected 53- to 63-yr-old men were randomized into two identical groups: an intervention (EX) group and a reference (CO) group, of which 89 men remained until the final analysis (EX: n = 47; CO: n = 42). The EX group trained for 30–60 min three to five times a week with an intensity of 40–60% of maximal oxygen consumption. The mean weekly energy expenditure of the training program for the 5-yr training period was 3.80 MJ, and 71% of the EX group exceeded the mean. The EX group had a significantly ( P < 0.01) higher oxygen consumption at ventilatory aerobic threshold (V̇o2VT) than the CO group at the 5-yr time point. V̇o2VT had a tendency to increase in the EX group and decrease in the CO group (interaction P < 0.001) from the baseline to the 5-yr time point. Peak performance did not change. Low-frequency power of R-R interval variability decreased in the EX group ( P < 0.01, by 6%) from the baseline to the 5-yr time point. BPV did not change. In conclusion, low-intensity regular exercise training did not prevent HRV from decreasing or change BPV in 5 yr in older Finnish men.

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Effect of Mean Velocity to Critical Velocity Ratios on Bed Topography and Incipient Motion in a Meandering Channel: Experimental Investigation

10.20944/preprints202102.0198.v1 ◽

2021 ◽

Author(s):

Nargess Moghaddassi ◽

Seyed Habib Musavi-Jahromi ◽

Mohammad Vaghefi ◽

Amir Khosrojerdi

Keyword(s):

Experimental Investigation ◽

Critical Velocity ◽

Velocity Ratio ◽

Scour Depth ◽

Incipient Motion ◽

Mean Velocity ◽

Straight Path ◽

Meandering Channel ◽

Bed Topography ◽

The Mean

As 180-degree meanders are observed in abundance in nature, a meandering channel with two consecutive 180-degree bends was designed and constructed to investigate bed topography variations. These two 180-degree mild bends are located between two upstream and downstream straight paths. In this study, different mean velocity to critical velocity ratios have been tested at the upstream straight path to determine the meander's incipient motion. To this end, bed topography variations along the meander and the downstream straight path were addressed for different mean velocity to critical velocity ratios. In addition, the upstream bend's effect on the downstream bend has been investigated. Results indicated that the maximum scour depth at the downstream bend has increased as a result of changing the mean velocity to critical velocity ratio from 0.8 to 0.84, 0.86, 0.89, 0.92, 0.95, and 0.98 by respectively 1.5, 2.5, 5, 10, 12, and 26 times. Moreover, increasing the ratio increased the maximum sedimentary height by 3, 10, 23, 48, 49, and 56 times. The upstream bend's incipient motion was observed for the mean velocity to critical velocity ratio of 0.89, while the downstream bend was equal to 0.78.

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Relación entre la potencia y velocidad en press de banca y la velocidad de lanzamiento de balón en jugadores profesionales de balonmano (Relationship between barbell power and velocity in bench press exercise and ball throwing velocity in professional ha

Retos ◽

10.47197/retos.v1i40.82710 ◽

2020 ◽

pp. 53-59

Author(s):

Iker Javier Bautista ◽

Juan Vicente-Mampel ◽

Luis Baraja-Vegas ◽

Isidoro Martínez

Keyword(s):

Bench Press ◽

Average Power ◽

Mean Velocity ◽

Specific Performance ◽

Relevant Variables ◽

The Mean ◽

Incremental Protocol ◽

The One ◽

The Relationship ◽

Correlation Range

Los objetivos de este estudio fueron (a) analizar la relación existente entre la una repetición máxima (1-RM) en press de banca y la velocidad de lanzamiento en jugadores de balonmano U18 de nivel internacional y, (b) analizar qué variables del ejercicio del press de banca son más relevantes en el rendimiento específico (velocidad de lanzamiento del balón) durante el test de velocidad de lanzamiento (T3-Step). Dieciséis jugadores de la Selección Española de Balonmano Juvenil participaron en la presente investigación. Todos los sujetos realizaron un protocolo incremental en el ejercicio del press de banca, además del T3-Step de velocidad de lanzamiento del balón. Por un lado, se analizó la relación existente entre la velocidad media (Velmedia), velocidad media de la fase propulsiva (VelMFP), velocidad pico (Velpico), potencia media (Potmedia), potencia media de la fase propulsiva (PotMFP), y potencia pico (Potpico) en todo el espectro de cargas en relación con la velocidad de lanzamiento. También se realizaron los mismos análisis con la carga en donde se obtuvo la máxima potencia media (CargaMP). Los resultados mostraron, por un lado que el rango de correlación de la CargaMP, PotmediaMP, PotMFPMP y PotpicoMP y la velocidad de lanzamiento fueron de .61 (p= .012), .702 (p< .01), .734 (p< .01) y .63 (p< .01), respectivamente. El coeficiente de correlación de Pearson entre la 1-RM y la velocidad de lanzamiento fue de r = .61 (p < .01). En conclusión, las variables relevantes a nivel de rendimiento específico con la velocidad de lanzamiento fueron la 1RM, la CargaMP, la PotMFPMP y la VelMFPMP. Todas estas analizadas en función del 60% de la 1-RM. Abstract. The objectives of this study were (a) to analyze the relationship between one repetition maximum (1-RM) in free bench press exercise and ball throwing velocity in handball players U18 of international level and, (b) to analyze which variables of bench press exercise are more relevant in the specific performance during the ball throwing velocity test (T3-Step). Sixteen (n = 16) players of the Spanish Youth Handball Team participated in the present investigation. All subjects included performed an incremental protocol bench press exercise, in addition to the T3-Step. On the one hand, it analyzed the relationship between the mean velocity (Velmean), the mean velocity of propulsive phase (VelmeanPP), peak velocity (Velpeak), the average power (Powermean), the average power of the propulsive phase (PowermeanPP), and peak power (Powerpeak) over the entire spectrum of charges in relation to the launch speed. The same analyzes were also obtained with the load where the maximum average power (LoadMP). The results obtained, on the one hand that the correlation range of the LoadMP, PowermeanPP, PowerMPPMP and PowerpeakPP and ball throwing velocity were .61 (p = .012), .70 (p < .01), .73 (p < .01) and 0.63 (p < .01), respectively. The correlation coefficient between the 1-RM and ball throwing velocity was r = 0.61 (p< .01). In conclusion, the relevant variables at the specific performance level with the ball throwing velocity were 1-RM, LoadMP, PowerMFPMP and VelMFPMP. All these analyzed according to 60% of the 1-RM.

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The time course of adaptations in thermoneutral maximal oxygen consumption following heat acclimation

European Journal of Applied Physiology ◽

10.1007/s00421-019-04218-2 ◽

2019 ◽

Vol 119 (10) ◽

pp. 2391-2399 ◽

Cited By ~ 5

Author(s):

Mark Waldron ◽

O. Jeffries ◽

J. Tallent ◽

S. Patterson ◽

V. Nevola

Keyword(s):

Oxygen Consumption ◽

Oxygen Uptake ◽

Maximal Oxygen Uptake ◽

Time Course ◽

Aerobic Power ◽

Linear Time ◽

Maximal Oxygen Consumption ◽

Training Group ◽

Heat Acclimation ◽

Non Linear

Abstract Purpose This study investigated the effects of a 10-day heat acclimation (HA) programme on the time course of changes in thermoneutral maximal oxygen uptake ($$\dot{V}$$ V ˙ O2max) during and up to 10 days post-HA. Methods Twenty-two male cyclists were assigned to a HA or control (Con) training group following baseline ramp tests of thermoneutral $$\dot{V}$$ V ˙ O2max. Ten days of fixed-intensity (50% baseline $$\dot{V}$$ V ˙ O2max) indoor cycling was performed in either ~ 38.0 °C (HA) or ~ 20 °C (Con). $$\dot{V}$$ V ˙ O2max was re-tested on HA days 5, 10 and post-HA days 1, 2, 3, 4, 5 and 10. Results $$\dot{V}$$ V ˙ O2max initially declined across time in both groups during training (P < 0.05), before increasing in the post-HA period in both groups (P < 0.05). However, $$\dot{V}$$ V ˙ O2max was higher than control by post-HA day 4 in the HA group (P = 0.046). Conclusions The non-linear time course of $$\dot{V}$$ V ˙ O2max adaptation suggests that post-testing should be performed 96-h post-training to identify the maximal change for most individuals. In preparation for training or testing, athletes can augment their aerobic power in thermoneutral environments by performing 10 days HA, but the full effects will manifest at varying stages of the post-HA period.

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The Relationship of the 6-Min Walk Test to Maximal Oxygen Consumption in Transplant Candidates With End-Stage Lung Disease

CHEST Journal ◽

10.1378/chest.108.2.452 ◽

1995 ◽

Vol 108 (2) ◽

pp. 452-459 ◽

Cited By ~ 151

Author(s):

Lawrence Cahalin ◽

Paul Pappagianopoulos ◽

Stella Prevost ◽

John Wain ◽

Leo Ginns

Keyword(s):

Oxygen Consumption ◽

Lung Disease ◽

Maximal Oxygen Consumption ◽

Walk Test ◽

Transplant Candidates ◽

End Stage ◽

Relationship Of ◽

The Relationship

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Measurements and numerical simulations of snow-particle saltation

Annals of Glaciology ◽

10.1017/s0260305500014786 ◽

1998 ◽

Vol 26 ◽

pp. 184-190 ◽

Cited By ~ 10

Author(s):

K. Nishimura ◽

K. Sugiura ◽

M. Nemoto ◽

N. Maeno

Keyword(s):

Friction Velocity ◽

Laser Sheet ◽

Impact Angle ◽

Wind Tunnel Experiments ◽

Mean Velocity ◽

Measured Probability ◽

The Mean ◽

Snow Particle ◽

The Relationship ◽

Particle Saltation

First, wind-tunnel experiments were carried out to measure the trajectories of saltating snow particles with varying friction velocity. Trajectories of saltating particles were recorded by a video system with a laser sheet and trajectory statistics, such as ejection and impact velocities and angles, were obtained for each particle. Parabolic trajectories are considerably elongated with an increase in the friction velocity; impact angle was approximately the same but ejection angle decreased with increasing friction velocity. Furthermore, it should be noted that the gradient of flux decay with height decreased with friction velocity. In the experiments, a snow-particle counter, which can sense not only the number of particles but also their diameters, was introduced. The flux distribution and the transport rate obtained as a function of the particle size gave a new insight into the relationship with the friction velocity.Trajectories of saltating grains were computed, using the measurements of the initial ejection velocities, angles and the mean velocity profile of the air. The results agreed reasonably with our measurements. Using the measured probability distribution of the ejection velocities, an ensemble of trajectories was computed and thence the vertical profiles of stream-wise fluxes. The exponential decay of the flux on height was obtained in all cases and it supports the basic validity of the model, although agreement is less than expected.

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