Oxygen intake in track and treadmill running with observations on the effect of air resistance
TL;DR: The relation of V̇O2 and speed was measured on seven athletes running on a cinder track and an all‐weather track and the results were compared with similar observations on four athletesRunning on a treadmill.
Abstract: 1. The relation of V(O2) and speed was measured on seven athletes running on a cinder track and an all-weather track. The results were compared with similar observations on four athletes running on a treadmill.2. In treadmill running the relation was linear and the zero intercept coincided with resting V(O2).3. In track running the relation was curvilinear, but was adequately represented by a linear regression over a range of speeds extending from 8.0 km/hr (2.2 m/sec) to 21.5 km/hr (6.0 m/sec). The slope of this line was substantially steeper than the regression line slope for treadmill running.4. The influence of air resistance in running was estimated from measurements of V(O2) on a subject running on a treadmill at constant speed against wind of varying velocity.5. The extra O(2) intake (DeltaV(O2)) associated with wind increased as the square of wind velocity. If wind velocity and running velocity are equal, as in running on a track in calm air, DeltaV(O2) will increase as the cube of velocity.6. It was estimated that the energy cost of overcoming air resistance in track running is about 8% of total energy cost at 21.5 km/hr (5000 m races) and 16% for sprinting 100 m in 10.0 sec.
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TL;DR: Equality of the energetic cost of treadmill and outdoor running is demonstrated with the use of a 1% treadmill grade over a duration of approximately 5 min and at velocities between 2.92 and 5.0 m s-1.
Abstract: When running indoors on a treadmill, the lack of air resistance results in a lower energy cost compared with running outdoors at the same velocity. A slight incline of the treadmill gradient can be used to increase the energy cost in compensation. The aim of this study was to determine the treadmill gradient that most accurately reflects the energy cost of outdoor running. Nine trained male runners, thoroughly habituated to treadmill running, ran for 6 min at six different velocities (2.92, 3.33, 3.75, 4.17, 4.58 and 5.0 m s‐1) with 6 min recovery between runs. This routine was repeated six times, five times on a treadmill set at different grades (0%, 0%, 1%, 2%, 3%) and once outdoors along a level road. Duplicate collections of expired air were taken during the final 2 min of each run to determine oxygen consumption. The repeatability of the methodology was confirmed by high correlations (r = 0.99) and non‐significant differences between the duplicate expired air collections and between the repeated runs...
849 citations
TL;DR: It is concluded that human runners reach faster top speeds not by repositioning their limbs more rapidly in the air, but by applying greater support forces to the ground.
Abstract: We twice tested the hypothesis that top running speeds are determined by the amount of force applied to the ground rather than how rapidly limbs are repositioned in the air. First, we compared the ...
845 citations
Cites background from "Oxygen intake in track and treadmil..."
...This enabled us to eliminate the different resistances that our fast and slow subjects would encounter from air at their different top speeds (25), as well as the mechanical variability that occurs when subjects run at volitional rather than controlled speeds....
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TL;DR: There is a strong association between RE and distance running performance, with RE being a better predictor of performance than maximal oxygen uptake (V̇O2max) in elite runners who have a similar V̇ O2max.
Abstract: velocity of submaximal running, and is determined by measuring the steady-state consumption of oxygen ( ˙ VO2) and the respiratory exchange ratio. Taking body mass (BM) into consideration, runners with good RE use less energy and therefore less oxygen than runners with poor RE at the same velocity. There is a strong association between RE and distance running performance, with RE being a better predictor of performance than maximal oxygen uptake ( ˙ VO2max) in elite runners
844 citations
TL;DR: Examination of walking and running on a treadmill while speed was varied suggested that gait transitions behave like nonequilibrium phase transitions between attractors, consistent with a dynamic theory of locomotion in which preferred gaits are characterized by stable phase relationships and minimum energy expenditure.
Abstract: Why do humans switch from walking to running at a particular speed? It is proposed that gait transitions behave like nonequilibrium phase transitions between attractors. Experiment 1 examined walking and running on a treadmill while speed was varied. The transition occurred at the equal-energy separatrix between gaits, with predicted shifts in stride length and frequency, a qualitative reorganization in the relative phasing of segments within a leg, a sudden jump in relative phase, enhanced fluctuations in relative phase, and hysteresis. Experiment 2 dissociated speed, frequency, and stride length to show that the transition occurred at a constant speed near the energy separatrix. Results are consistent with a dynamic theory of locomotion in which preferred gaits are characterized by stable phase relationships and minimum energy expenditure, and gait transitions by a loss of stability and the reduction of energetic costs.
425 citations
TL;DR: The mechanics of the locomotion cannot be simply described using the models for walking and running because step frequency, the proportion of step duration during which the foot is in contact with the ground, the position of the limbs, the force exerted on the ground and the time of its application are all different.
Abstract: Walking and running, the two basic gaits used by man, are very complex movements. They can, however, be described using two simple models: an inverted pendulum and a spring. Muscles must contract at each step to move the body segments in the proper sequence but the work done is, in part, relieved by the interplay of mechanical energies, potential and kinetic in walking, and elastic in running. This explains why there is an optimal speed of walking (minimal metabolic cost of about 2 J.kg–1·m–1 at about 1.11 m.s–1) and why the cost of running is constant and independent of speed (about 4 J.kg–1.m–1). Historically, the mechanical work of locomotion has been divided into external and internal work. The former is the work done to raise and accelerate the body centre of mass (m) within the environment, the latter is the work done to accelerate the body segments with respect to the centre of m. The total work has been calculated, somewhat arbitrarily, as the sum of the two. While the changes of potential and kinetic energies can be accurately measured, the contribution of the elastic energy cannot easily be assessed, nor can the true work performed by the muscles. Many factors can affect the work of locomotion - the gradient of the terrain, body size (height and body m), and gravity. The partitioning of positive and negative work and their different efficiencies explain why the most economical gradient is about –10% (1.1 J.kg–1.m–1 at 1.3 m.s–1 for walking, and 3.1 J.kg–1.m–1 at between 3 and 4 m·s–1 for running). The mechanics of walking of children, pigmies and dwarfs, in particular the recovery of energy at each step, is not different from that of taller (normal sized) individuals when the speed is expressed in dynamically equivalent terms (Froude number). An extra load, external or internal (obesity) affects internal and external work according to the distribution of the added m. Different gravitational environments determine the optimal speed of walking and the speed of transition from walking to running: at more than 1 g it is easier to walk than to run, and it is the opposite at less than 1 g. Passive aids, such as skis or skates, allow an increase in the speed of progression, but the mechanics of the locomotion cannot be simply described using the models for walking and running because step frequency, the proportion of step duration during which the foot is in contact with the ground, the position of the limbs, the force exerted on the ground and the time of its application are all different.
402 citations
Cites background from "Oxygen intake in track and treadmil..."
...This is particularly true when running on a treadmill; in reality, on a track, air resistance accounts for 8% of the total energy cost at 6 m s–1 (the speed of middle distance races) and 16% at 10 m s–1 (the speed of a sprint; Pugh 1970)....
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References
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01 Jan 1955
TL;DR: The flow laws of the actual flows at high Reynolds numbers differ considerably from those of the laminar flows treated in the preceding part, denoted as turbulence as discussed by the authors, and the actual flow is very different from that of the Poiseuille flow.
Abstract: The flow laws of the actual flows at high Reynolds numbers differ considerably from those of the laminar flows treated in the preceding part. These actual flows show a special characteristic, denoted as turbulence. The character of a turbulent flow is most easily understood the case of the pipe flow. Consider the flow through a straight pipe of circular cross section and with a smooth wall. For laminar flow each fluid particle moves with uniform velocity along a rectilinear path. Because of viscosity, the velocity of the particles near the wall is smaller than that of the particles at the center. i% order to maintain the motion, a pressure decrease is required which, for laminar flow, is proportional to the first power of the mean flow velocity. Actually, however, one ob~erves that, for larger Reynolds numbers, the pressure drop increases almost with the square of the velocity and is very much larger then that given by the Hagen Poiseuille law. One may conclude that the actual flow is very different from that of the Poiseuille flow.
17,321 citations
782 citations
TL;DR: In this article, indirect calorimetric measurements were made on two athletes running at different speeds up to 22 km/hr at grades from -20 to +15; the function was found to be linearly related to speed.
Abstract: Indirect calorimetric measurements were made on two athletes running at different speeds up to 22 km/hr at grades from -20 to +15%; the function was found to be linearly related to speed. Within th...
667 citations
TL;DR: Oxygen consumption, along with lactic and pyruvic acid in blood, have been measured throughout the performance of heavy muscular exercise of different intensities, all leading to exhaustion in 1–10 minutes.
Abstract: Oxygen consumption, along with lactic and pyruvic acid in blood, have been measured throughout the performance of heavy muscular exercise of different intensities, all leading to exhaustion in 1–10...
182 citations
TL;DR: The alactacid oxygen debt contraction is a faster process and it requires 10–30 sec for completion, while the lactacid debt process is completed in about 40 sec in the most strenous exercise, therefore, at the highest workloads, the only energy source available after 40 sec resides in oxidative processes.
Abstract: The speed of lactic acid formation in blood has been measured in man as a function of the intensity of exercise and was found to reach a maximum of about 36 mg lactic acid/liter blood per sec, corr...
145 citations