High-speed running performance is largely unaffected by hypoxic reductions in aerobic power

1999 ◽  
Vol 86 (6) ◽  
pp. 2059-2064 ◽  
Author(s):  
Peter G. Weyand ◽  
Cherie S. Lee ◽  
Ricardo Martinez-Ruiz ◽  
Matthew W. Bundle ◽  
Matthew J. Bellizzi ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
High Speed ◽  
Aerobic Power ◽  
Metabolic Cost ◽  
Adult Men ◽  
Hypoxic Conditions ◽  
Anaerobic Energy ◽  
Power Outputs ◽  
Maximal Metabolic Power ◽  
Human Running

We tested the importance of aerobic metabolism to human running speed directly by altering inspired oxygen concentrations and comparing the maximal speeds attained at different rates of oxygen uptake. Under both normoxic (20.93% O2) and hypoxic (13.00% O2) conditions, four fit adult men completed 15 all-out sprints lasting from 15 to 180 s as well as progressive, discontinuous treadmill tests to determine maximal oxygen uptake and the metabolic cost of steady-state running. Maximal aerobic power was lower by 30% (1.00 ± 0.15 vs. 0.77 ± 0.12 ml O2 ⋅ kg−1 ⋅ s−1) and sprinting rates of oxygen uptake by 12–25% under hypoxic vs. normoxic conditions while the metabolic cost of submaximal running was the same. Despite reductions in the aerobic energy available for sprinting under hypoxic conditions, our subjects were able to run just as fast for sprints of up to 60 s and nearly as fast for sprints of up to 120 s. This was possible because rates of anaerobic energy release, estimated from oxygen deficits, increased by as much as 18%, and thus compensated for the reductions in aerobic power. We conclude that maximal metabolic power outputs during sprinting are not limited by rates of anaerobic metabolism and that human speed is largely independent of aerobic power during all-out runs of 60 s or less.

High-speed running performance: a new approach to assessment and prediction

2003 ◽  
Vol 95 (5) ◽  
pp. 1955-1962 ◽  
Author(s):  
Matthew W. Bundle ◽  
Reed W. Hoyt ◽  
Peter G. Weyand
Keyword(s):  
Oxygen Uptake ◽  
Performance Assessment ◽  
High Speed ◽  
Aerobic Power ◽  
Anaerobic Power ◽  
Maximum Speed ◽  
Treadmill Test ◽  
New Approach ◽  
Running Performance ◽  
Trained Runners

We hypothesized that allout running speeds for efforts lasting from a few seconds to several minutes could be accurately predicted from two measurements: the maximum respective speeds supported by the anaerobic and aerobic powers of the runner. To evaluate our hypothesis, we recruited seven competitive runners of different event specialties and tested them during treadmill and overground running on level surfaces. The maximum speed supported by anaerobic power was determined from the fastest speed that subjects could attain for a burst of eight steps (∼3 s or less). The maximum speed supported by aerobic power, or the velocity at maximal oxygen uptake, was determined from a progressive, discontinuous treadmill test to failure. All-out running speeds for trials of 3-240 s were measured during 10-13 constant-speed treadmill runs to failure and 4 track runs at specified distances. Measured values of the maximum speeds supported by anaerobic and aerobic power, in conjunction with an exponential constant, allowed us to predict the speeds of all-out treadmill trials to within an average of 2.5% ( R2 = 0.94; n = 84) and track trials to within 3.4% ( R2 = 0.86; n = 28). An algorithm using this exponent and only two of the all-out treadmill runs to predict the remaining treadmill trials was nearly as accurate (average = 3.7%; R2 = 0.93; n = 77). We conclude that our technique 1) provides accurate predictions of high-speed running performance in trained runners and 2) offers a performance assessment alternative to existing tests of anaerobic power and capacity.

Energetics of high-speed running: integrating classical theory and contemporary observations

2005 ◽  
Vol 288 (4) ◽  
pp. R956-R965 ◽  
Author(s):  
Peter G. Weyand ◽  
Matthew W. Bundle
Keyword(s):  
High Speed ◽  
Aerobic Power ◽  
Anaerobic Power ◽  
Treadmill Running ◽  
Distance Runners ◽  
Long Distance ◽  
Classic Theory ◽  
Direct Measurements ◽  
Power Outputs ◽  
The Individual

We hypothesized that the anaerobic power and aerobic power outputs during all-out runs of any common duration between 10 and 150 s would be proportional to the maximum anaerobic (Ėan-max) and aerobic powers (Ėaer-max) available to the individual runner. Seventeen runners who differed in Ėan-max and Ėaer-max (5 sprinters, 5 middle-distance runners, and 7 long distance runners) were tested during treadmill running on a 4.6° incline. Ėan-max was estimated from the fastest treadmill speed subjects could attain for eight steps. Ėaer-max was determined from a progressive, discontinuous, treadmill test to failure. Oxygen deficits and rates of uptake were measured to assess the respective anaerobic and aerobic power outputs during 11–16 all-out treadmill runs that elicited failure between 10 and 220 s. We found that, during all-out runs of any common duration, the relative anaerobic and aerobic powers utilized were largely the same for sprint, middle-distance, and long-distance subjects. The similar fractional utilization of the Ėan-max and Ėaer-max available during high-speed running 1) provides empirical values that modify and advance classic theory, 2) allows rates of anaerobic and aerobic energy release to be quantified from individual maxima and run durations, and 3) explains why the high-speed running performances of different event specialists can be accurately predicted ( R2 = 0.97; n = 254) from two direct measurements and the same exponential time constant.

scholarly journals Is There an Optimal Pole Length for Double Poling in Cross Country Skiing?

2017 ◽  
Vol 33 (3) ◽  
pp. 197-202 ◽  
Author(s):  
Franziska Onasch ◽  
Anthony Killick ◽  
Walter Herzog
Keyword(s):  
Oxygen Uptake ◽  
Body Height ◽  
Metabolic Cost ◽  
Male Athletes ◽  
Double Poling ◽  
Acute Study ◽  
Ground Contact Time ◽  
Cross Country Skiing ◽  
Cross Country ◽  
The Given

The aim of this study was to determine the effects of pole length on energy cost and kinematics in cross country double poling. Seven sub-elite male athletes were tested using pole sets of different lengths (ranging between 77% and 98% of participants’ body height). Tests were conducted on a treadmill, set to a 2% incline and an approximate racing speed. Poling forces, contact times, and oxygen uptake were measured throughout the testing. Pole length was positively correlated with ground contact time (r = .57, p < .001) and negatively correlated with poling frequency (r = −.48, p = .003). Pole length was also positively correlated with pole recovery time and propulsive impulse produced per poling cycle (r = .36, p = .031; r = .35, p = .042, respectively). Oxygen uptake and pole length were negatively correlated (r = −.51, p = .004). This acute study shows that increasing pole length for double poling in sub-elite cross country skiers under the given conditions seems to change the poling mechanics in distinct ways, resulting in a more efficient poling action by decreasing an athlete’s metabolic cost.

Breathing in brief exercise

1960 ◽  
Vol 15 (4) ◽  
pp. 583-588 ◽  
Author(s):  
F. N. Craig ◽  
E. G. Cummings
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Uptake ◽  
Respiratory Exchange Ratio ◽  
Metabolic Cost ◽  
Carbon Dioxide Tension ◽  
Minute Volume ◽  
Carbon Dioxide Output ◽  
Respiratory Minute Volume ◽  
Before And After

Two men ran for 20 or 60 seconds while inhaling air, oxygen or 4% carbon dioxide. Inspired respiratory minute volume was determined for each breath. Ventilation increased suddenly in the first breath with minimal changes in end-expiratory carbon dioxide tension and respiratory exchange ratio to a rate that remained constant for 20 seconds before increasing further. The rate of carbon dioxide output was uniform during the first 20 seconds. A 12% grade did not increase ventilation or oxygen uptake during runs of 20 seconds, but in the first minute of recovery, ventilation was 64% greater than after level runs. Inhalation of oxygen inhibited ventilation by 24% in the 20-second periods before and after the end of a 60-second run. Inhalation of carbon dioxide begun at rest produced increments in ventilation and end-expiratory carbon dioxide tension that varied little during running and recovery. In the 20-second runs ventilation varied with speed but appeared independent of ultimate metabolic cost. Submitted on January 21, 1960

scholarly journals Metabolic cost of generating horizontal forces during human running

1999 ◽  
Vol 86 (5) ◽  
pp. 1657-1662 ◽  
Author(s):  
Young-Hui Chang ◽  
Rodger Kram
Keyword(s):  
Body Weight ◽  
Oxygen Consumption ◽  
Metabolic Cost ◽  
Ground Reaction Forces ◽  
Vertical Force ◽  
Order Of Magnitude ◽  
Reaction Forces ◽  
The Cost ◽  
Support Body Weight ◽  
Human Running

Previous studies have suggested that generating vertical force on the ground to support body weight (BWt) is the major determinant of the metabolic cost of running. Because horizontal forces exerted on the ground are often an order of magnitude smaller than vertical forces, some have reasoned that they have negligible cost. Using applied horizontal forces (AHF; negative is impeding, positive is aiding) equal to −6, −3, 0, +3, +6, +9, +12, and +15% of BWt, we estimated the cost of generating horizontal forces while subjects were running at 3.3 m/s. We measured rates of oxygen consumption (V˙o 2) for eight subjects. We then used a force-measuring treadmill to measure ground reaction forces from another eight subjects. With an AHF of −6% BWt,V˙o 2 increased 30% compared with normal running, presumably because of the extra work involved. With an AHF of +15% BWt, the subjects exerted ∼70% less propulsive impulse and exhibited a 33% reduction inV˙o 2. Our data suggest that generating horizontal propulsive forces constitutes more than one-third of the total metabolic cost of normal running.

scholarly journals Elastic energy savings and active energy cost in a simple model of running

2021 ◽  
Vol 17 (11) ◽  
pp. e1009608
Author(s):  
Ryan T. Schroeder ◽  
Arthur D. Kuo
Keyword(s):  
Elastic Energy ◽  
Energy Cost ◽  
Energy Savings ◽  
Mechanical Energy ◽  
Metabolic Cost ◽  
The Body ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Mass Model ◽  
Human Running

The energetic economy of running benefits from tendon and other tissues that store and return elastic energy, thus saving muscles from costly mechanical work. The classic “Spring-mass” computational model successfully explains the forces, displacements and mechanical power of running, as the outcome of dynamical interactions between the body center of mass and a purely elastic spring for the leg. However, the Spring-mass model does not include active muscles and cannot explain the metabolic energy cost of running, whether on level ground or on a slope. Here we add explicit actuation and dissipation to the Spring-mass model, and show how they explain substantial active (and thus costly) work during human running, and much of the associated energetic cost. Dissipation is modeled as modest energy losses (5% of total mechanical energy for running at 3 m s-1) from hysteresis and foot-ground collisions, that must be restored by active work each step. Even with substantial elastic energy return (59% of positive work, comparable to empirical observations), the active work could account for most of the metabolic cost of human running (about 68%, assuming human-like muscle efficiency). We also introduce a previously unappreciated energetic cost for rapid production of force, that helps explain the relatively smooth ground reaction forces of running, and why muscles might also actively perform negative work. With both work and rapid force costs, the model reproduces the energetics of human running at a range of speeds on level ground and on slopes. Although elastic return is key to energy savings, there are still losses that require restorative muscle work, which can cost substantial energy during running.

scholarly journals Innate antiviral defense demonstrates high energetic efficiency in a bony fish

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Mark P. Polinski ◽  
Yangfan Zhang ◽  
Phillip R. Morrison ◽  
Gary D. Marty ◽  
Colin J. Brauner ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Allostatic Load ◽  
Sockeye Salmon ◽  
Acute Stress ◽  
Metabolic Cost ◽  
High Load ◽  
Energetic Efficiency ◽  
Antiviral Defense ◽  
Life Threatening ◽  
Interferon System

Abstract Background Viruses can impose energetic demands on organisms they infect, in part by hosts mounting resistance. Recognizing that oxygen uptake reliably indicates steady-state energy consumption in all vertebrates, we comprehensively evaluated oxygen uptake and select transcriptomic messaging in sockeye salmon challenged with either a virulent rhabdovirus (IHNV) or a low-virulent reovirus (PRV). We tested three hypotheses relating to the energetic costs of viral resistance and tolerance in this vertebrate system: (1) mounting resistance incurs a metabolic cost or limitation, (2) induction of the innate antiviral interferon system compromises homeostasis, and (3) antiviral defenses are weakened by acute stress. Results IHNV infections either produced mortality within 1–4 weeks or the survivors cleared infections within 1–9 weeks. Transcription of three interferon-stimulated genes (ISGs) was strongly correlated with IHNV load but not respiratory performance. Instead, early IHNV resistance was associated with a mean 19% (95% CI = 7–31%; p = 0.003) reduction in standard metabolic rate. The stress of exhaustive exercise did not increase IHNV transcript loads, but elevated host inflammatory transcriptional signaling up to sevenfold. For PRV, sockeye tolerated high-load systemic PRV blood infections. ISG transcription was transiently induced at peak PRV loads without associated morbidity, microscopic lesions, or major changes in aerobic or anaerobic respiratory performance, but some individuals with high-load blood infections experienced a transient, minor reduction in hemoglobin concentration and increased duration of excess post-exercise oxygen consumption. Conclusions Contrary to our first hypothesis, effective resistance against life-threatening rhabdovirus infections or tolerance to high-load reovirus infections incurred minimal metabolic costs to salmon. Even robust systemic activation of the interferon system did not levy an allostatic load sufficient to compromise host homeostasis or respiratory performance, rejecting our second hypothesis that this ancient innate vertebrate antiviral defense is itself energetically expensive. Lastly, an acute stress experienced during testing did not weaken host antiviral defenses sufficiently to promote viral replication; however, a possibility for disease intensification contingent upon underlying inflammation was indicated. These data cumulatively demonstrate that fundamental innate vertebrate defense strategies against potentially life-threatening viral exposure impose limited putative costs on concurrent aerobic or energetic demands of the organism.

scholarly journals Aerobic Power in Prepubescent Children with Different Levels of Physical Activity (Potencia Aeróbica en Niños Prepubescentes con Diferentes Niveles de Actividad Física)

Retos ◽  
2015 ◽  
pp. 203-205
Author(s):  
Luis Paulo Gomes Mascarenhas ◽  
Marcos Tadeu Grzelczak ◽  
William Cordeiro de Souza ◽  
Antonio Stabelini Neto ◽  
Yamileth Chacón-Araya ◽  
...  
Keyword(s):  
Physical Activity ◽  
Oxygen Uptake ◽  
Physical Activity Level ◽  
Aerobic Power ◽  
Peak Oxygen Uptake ◽  
Activity Level ◽  
Similar Amount ◽  
Physiological Indicators ◽  
Post Hoc ◽  
Activity Diary

The purpose of the study was to compare the aerobic power of prepubescent children (Tanner 1 stage). Participants were 95 children between 7 and 9 years old, divided into 4 physical activity level groups: a) Trained (n = 24), b) Sport beginners (n = 23), c) Active (n = 24), and d) Sedentary (n = 24). Physical activity level was determined by a three-day physical activity diary. Subjects performed a treadmill Balk protocol to obtain their peak oxygen uptake. Comparisons were made using ANOVA two-way and post hoc Tukey followed-up the significant differences for p< 0,05. Trained, sport beginners and active children presented similar amount of physical activity level, but they significantly differ from the sedentary children (p< 0.05). Overall boys (50.67 ± 8.52 ml/kg/min) had higher relative peak oxygen uptake than girls (45.19 ± 6.44 ml/kg/min). The gender by group interaction showed that this difference is explained by the superior values of the trained boys (58.80 ± 8.98 ml/kg/min) when compared to trained girls (47.51 ± 5.68 ml/kg/min), even though they presented the same amount of physical activity level. The trained group (53.16 ± 9.34 ml/kg/min) showed higher relative peak oxygen uptake compared to sport beginners (48.90 ± 6.54 ml/kg/min), active children (45.46 ± 7.50 ml/kg/min) and sedentary children (44.63 ± 9.52 ml/kg/min). The results suggest that prepubescent children that participate in systematized trained programs have better physiological indicators for aerobic fitness.Key words. aerobic power, physical activity, children.Resumen. El propósito del estudio fue comparar la potencia aeróbica de niños prepubescentes (Estadio de Tanner 1). Participaron 95 niños y niñas con edades entre 7 y 9 años, divididos en 4 grupos basados en sus niveles de actividad física: a) Entrenados (n = 24), b) Principiantes en deportes (n = 23), c) Activos (n = 24), y d) Sedentarios (n = 24). Los niveles de actividad física se determinaron por medio de un diario de actividad física de tres días. Los participantes realizaron el protocolo de Balke en banda sin fin para obtener el consumo de oxígeno pico. Se hicieron comparaciones con ANOVA de dos vías y post hoc de Tukey cuando se encontraron diferencias significativas a un p < 0.05. Los niños prepubescentes entrenados, principiantes en deportes y activos presentaron niveles de actividad física similares, pero fueron significativamente diferentes de los niños sedentarios (p < 0.05). En general, los niños presentaron mayor consumo de oxígeno pico (50.67 ± 8.52 ml/kg/min) que las niñas (45.19 ± 6.44 ml/kg/min). La interacción de sexo por grupo mostró que esta diferencia se explica por el mayor valor de los niños entrenados (58.80 ± 8.98 ml/kg/min) cuando se les comparó con las niñas entrenadas (47.51 ± 5.68 ml/kg/min), aunque tuvieran el mismo nivel de actividad física. El grupo entrenado (53.16 ± 9.34 ml/kg/min) presentó mayores valores de consumo de oxígeno pico comparados con los principiantes (48.90 ± 6.54 ml/kg/min), niños activos (45.46 ± 7.50 ml/kg/min) y niños sedentarios (44.63 ± 9.52 ml/kg/min). Los resultados sugieren que los niños prepubescentes que participan en programas de entrenamiento sistemáticos tienen mejores indicadores fisiológicos de capacidad aeróbica.Palabras claves. potencia aeróbica, actividad física, niños

Effects of Arms-Only Swimming Training on Performance, Movement Economy, and Aerobic Power

2008 ◽  
Vol 3 (3) ◽  
pp. 294-304 ◽  
Author(s):  
Maria Konstantaki ◽  
Edward Winter ◽  
Ian Swaine
Keyword(s):  
Oxygen Uptake ◽  
Training Program ◽  
Exercise Intensity ◽  
Exercise Test ◽  
Aerobic Power ◽  
Swimming Performance ◽  
Peak Exercise ◽  
Control Group ◽  
Swimming Training ◽  
Weekly Training

Context:Forward propulsion in freestyle swimming is predominantly achieved through arm action. Few studies have assessed the effects of arm training on arm power and swimming performance, yet there have not been any investigations on the effects of arms-only swimming training on swimming performance and physiological responses to arm exercise.Purpose:To investigate the changes in arms-only and full-stroke swimming performance, movement economy and aerobic power after an arms-only swimming training program.Methods:Fifteen male county level swimmers were assigned either to an experimental (ES, n = 8) or control group (CS, n = 7). For six weeks ES performed arms-only freestyle swimming exercises for 20% of their weekly training distance three times per week, whereas CS performed their usual swimming training. Before and after the training program, both groups performed a) two time trials, 186 m using arms-only (186ARMS) and 372 m using full-stroke (372FULL) freestyle swimming, and b) an incremental arm-pulling exercise test. The time to complete the trials was recorded. Peak oxygen uptake (VO2peak), peak exercise intensity (EIpeak) submaximal oxygen uptake at 60 W (VO2−60) and exercise intensity at ventilatory threshold (VTW) were determined from the exercise test.Results:After training, ES had improved in 186ARMS (−14.2 ± 3.6%, P = .03), VO2−60 (−22.5 ± 2.3%, P = .04), EIpeak (+17.8 ± 4.2%, P = .03), and VTW (+18.9 ± 2.3%, P = .02), but not in VO2peak (P = .09) or in 372FULL (P = .07). None of the measures changed in CS (P > .05).Conclusion:Arms-only swimming training at 20% of the weekly training distance is an effective method to improve arm conditioning during the preparatory phase of the annual training cycle.

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