scholarly journals The dynamics of bicycle pedalling

1928 ◽  
Vol 103 (724) ◽  
pp. 225-233 ◽  
Keyword(s):  
Bicycle Ergometer ◽  
Maximum Force ◽  
External Work ◽  
Constant Resistance ◽  
Recent Developments ◽  
Human Limb ◽  
Constant Slope ◽  
Maximal Effort ◽  
Bodily Condition ◽  
Muscular Action

According to recent developments in the theory of muscular action, the average external force exerted during a muscular movement, carried out with maximal effort, may be regarded as equal to a constant theoretical force diminished by an amount proportional to the speed of movement. As a deduction from this, the relation between certain quantities involved in a specified type of muscular exercise can be expressed in the form of a mathematical equation. The equation can then be tested by experiment. Certain kinds of human limb movements have already been subjected to this form of analysis (5), (6), (7), (8). In the present paper is described a similar investigation of the movements of pedalling a bicycle. Consider the case of a subject pedalling a bicyle against a constant resistance. The resistance might be due to a hill of constant slope, or, in the case of laboratory experiments with a bicycle ergometer, to the friction of a band applied to the wheel. Let P be the maximum force (averaged over the whole range of foot movement) that can he exerted by the leg at right angles to the pedal crank when the rate of pedalling is such that one foot movement ( i. e. , half a complete revolution of the crank) is completed in t seconds. Then according to the theory, the relation between P and t should be capable of expression in the form, P = P 0 (1 - k/t ), where P 0 kind k are constants, represents the maximum force that could be exerted at right angles to the pedal crank, and would be attained only if the movement could take place infinitely slowly; while k represents the shortest time in which the movement could be completed, and would be attained only if no external work were done. The constants have a theoretical meaning only, and cannot be measured directly. If the theory holds, they should be characteristic for a given subject in a given bodily condition.

Prediction of Maximal Effort Bicycle Ergometer Endurance Performance

1985 ◽  
Vol 06 (04) ◽  
pp. 190-196 ◽  
Author(s):  
K. Barlow ◽  
A. Weltman ◽  
R. Schurrer ◽  
J. Henritze
Keyword(s):  
Endurance Performance ◽  
Bicycle Ergometer ◽  
Maximal Effort

Dynamic knee extension as model for study of isolated exercising muscle in humans

1985 ◽  
Vol 59 (5) ◽  
pp. 1647-1653 ◽  
Author(s):  
P. Andersen ◽  
R. P. Adams ◽  
G. Sjogaard ◽  
A. Thorboe ◽  
B. Saltin
Keyword(s):  
Femoral Vein ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Knee Extension ◽  
Bicycle Ergometer ◽  
The Body ◽  
External Work ◽  
Leg Muscles ◽  
Below The Knee ◽  
The Subject

In an attempt to approach a system of isolated exercising muscle in humans, a model has been developed that enables the study of muscle activity and metabolism over the quadriceps femoris (QF) muscles while the rest of the body remains relaxed. The simplest version includes the subject sitting on a table with a rod connecting the ankle and the pedal arm of a bicycle ergometer placed behind the subject. Exercise is performed by knee extension from a knee angle of 90 to approximately 170 degrees while flywheel momentum repositions the relaxed leg during flexion. Experiments where electromyographic recordings have been taken from biceps femoris, gastrocnemius, tibialis anterior, and other muscles in addition to QF indicate that only the QF is active and that there is an equal activation of the lateral, medial, and rectus femoris heads relative to maximum. Furthermore, virtually identical pulmonary O2 uptake (Vo2) during and without application of a pressure cuff below the knee emphasizes the inactivity of the lower leg muscles. The advantages of the model are that all external work can be localized to a single muscle group suitable for taking biopsies and that the blood flow in and sampling from the femoral vein are representative of the active muscles. Thus all measurements can be closely related to changes in the working muscle. Using this model we find that a linear relationship exists between external work and pulmonary Vo2 over the submaximal range and the maximal Vo2 per kilogram of muscle may be as much as twice as high as previously estimated.

scholarly journals Modeling Optimal Cadence as a Function of Time during Maximal Sprint Exercises Can Improve Performance by Elite Track Cyclists

2021 ◽  
Vol 11 (24) ◽  
pp. 12105
Author(s):  
Anna Katharina Dunst ◽  
René Grüneberger ◽  
Hans-Christer Holmberg
Keyword(s):  
Linear Regression Analysis ◽  
Bicycle Ergometer ◽  
Mean Power ◽  
Exponential Equation ◽  
Force Velocity ◽  
The Time Domain ◽  
Mean Power Output ◽  
Induced Changes ◽  
Constant Slope ◽  
Optimal Cadence

In track cycling sprint events, optimal cadence PRopt is a dynamic aspect of fatigue. It is currently unclear what cadence is optimal for an athlete’s performance in sprint races and how it can be calculated. We examined fatigue-induced changes in optimal cadence during a maximal sprint using a mathematical approach. Nine elite track cyclists completed a 6-s high-frequency pedaling test and a 60-s isokinetic all-out sprint on a bicycle ergometer with continuous monitoring of crank force and cadence. Fatigue-free force-velocity (F/v) and power-velocity (P/v) profiles were derived from both tests. The development of fatigue during the 60-s sprint was assessed by fixing the slope of the fatigue-free F/v profile. Fatigue-induced alterations in PRopt were determined by non-linear regression analysis using a mono-exponential equation at constant slope. The study revealed that PRopt at any instant during a 60-s maximal sprint can be estimated accurately using a mono-exponential equation. In an isokinetic mode, a mean PRopt can be identified that enables the athlete to generate the highest mean power output over the course of the effort. Adding the time domain to the fatigue-free F/v and P/v profiles allows time-dependent cycling power to be modelled independent of cadence.

Noncontingent Positive and Negative Feedback during Maximal Exercise

1992 ◽  
Vol 75 (1) ◽  
pp. 203-210 ◽  
Author(s):  
A. Fouad Kamal ◽  
Christine Blais
Keyword(s):  
Physical Education ◽  
Negative Feedback ◽  
Maximal Exercise ◽  
Elite Athletes ◽  
Bicycle Ergometer ◽  
Education Majors ◽  
Perceived Effort ◽  
Physical Education Majors ◽  
Positive And Negative Feedback ◽  
Maximal Effort

A closed skill, maximal effort on a bicycle ergometer was used to study the effects of noncontingent external feedback on performance, perceived effort, and the subject's assessment of the quality and accuracy of the feedback. The 47 subjects included elite athletes as well as physical education majors. They were asked to perform a series of 5 60-sec. trials of maximal effort, trials which included positive, negative, positive and negative, and no-feedback conditions. Although there were no significant effects on performance for the various feedback conditions, subjects judged the positive feedback favourably and as accurate, but negative feedback was judged unfavourably and considered to be inaccurate. This result is seen as supportive of the 1982 McCarrey, et al. supposition that successful athletes may have less need to internalize attributions of effect.

Recovery from maximal effort exercise: lactate disappearance and subsequent performance

1979 ◽  
Vol 47 (4) ◽  
pp. 677-682 ◽  
Author(s):  
A. Weltman ◽  
B. A. Stamford ◽  
C. Fulco
Keyword(s):  
Blood Lactate ◽  
Anaerobic Threshold ◽  
Performance Test ◽  
Bicycle Ergometer ◽  
Active Recovery ◽  
Subsequent Performance ◽  
Severe Exercise ◽  
Lactate Levels ◽  
Maximal Effort ◽  
Blood Lactate Levels

The effects of differing recovery patterns following maximal exercise on blood lactate disappearance and subsequent performance were examined. Nine subjects completed four randomly assigned experimental sessions. Each session consisted of a 5-min maximal effort performance test conducted on a Monark bicycle ergometer (T1) followed by 20 min of recovery and a second 5-min maximal effort performance test (T2). Blood lactate levels were measured during min 5, 10, 15, and 20 of recovery. Recovery patterns consisted of passive recovery (PR), active recovery below anaerobic threshold (AR less than AT), active recovery above anaerobic threshold (AR greater than AT), and active recovery above anaerobic threshold while breathing 100% oxygen (AR greater than AT + O2). Blood lactate levels prior to T2 were significantly different across treatments (P less than 0.05). Comparison among treatments and between T1 and T2 revealed no significant differences in work output. It was concluded that while lactate disappearance following severe exercise can be affected by varying the recovery pattern, elevated levels of blood lactate exert no demonstrable effect on maximal effort performance of 5-min duration.

Efficiency of trained subjects differing in maximal oxygen uptake and type of training

1981 ◽  
Vol 50 (2) ◽  
pp. 444-449 ◽  
Author(s):  
M. K. Stuart ◽  
E. T. Howley ◽  
L. B. Gladden ◽  
R. H. Cox
Keyword(s):  
Energy Expenditure ◽  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Causal Effect ◽  
Bicycle Ergometer ◽  
Work Rate ◽  
Distance Runners ◽  
External Work ◽  
The Relationship ◽  
Delta Efficiency

This study was undertaken to examine the relationship between energy expenditure and work rate on a bicycle ergometer in five sprinters and five distance runners who differed in maximal oxygen uptake (VO2max) and type of training. Each subject performed at work rates of 30, 60, 90, 120, and 150 watts (W). The relationship between energy expenditure and work rates was most accurately described by a quadratic curve for both groups: for sprinters, energy expenditure (kJ) = 11.57 + 0.1812 (W) + 0.00046 (W)2; for distance runners, energy expenditure (kJ) = 11.74 + 0.1386 (W) + 0.00060 (W)2. Delta efficiency (delta work accomplished divided by delta energy expended X 100%) decreased as work rate increased. Statistical analyses revealed no significant differences between groups in delta efficiency at the same work rate (P greater than 0.25) or at the same relative work rate (P greater than 0.75). These results suggest that differences in VO2max and/or type of training have little or no causal effect on the decrease in delta efficiency with increasing work rate. The observed decrease in delta efficiency may be due to increases in metabolism not directly related to the performance of the external work or to an increasing amount of unmeasured work as work rate increases on a bicycle ergometer.

Trends in Electron Energy Loss Spectroscopy

1977 ◽  
Vol 35 ◽  
pp. 228-229
Author(s):  
C. Colliex ◽  
P. Trebbia
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Materials Science ◽  
Analytical Technique ◽  
Recent Developments ◽  
Quantitative Results ◽  
Electron Microscopes ◽  
Electron Energy Loss ◽  
Primary Electrons

The physical foundations for the use of electron energy loss spectroscopy towards analytical purposes, seem now rather well established and have been extensively discussed through recent publications. In this brief review we intend only to mention most recent developments in this field, which became available to our knowledge. We derive also some lines of discussion to define more clearly the limits of this analytical technique in materials science problems.The spectral information carried in both low ( 0<ΔE<100eV ) and high ( >100eV ) energy regions of the loss spectrum, is capable to provide quantitative results. Spectrometers have therefore been designed to work with all kinds of electron microscopes and to cover large energy ranges for the detection of inelastically scattered electrons (for instance the L-edge of molybdenum at 2500eV has been measured by van Zuylen with primary electrons of 80 kV). It is rather easy to fix a post-specimen magnetic optics on a STEM, but Crewe has recently underlined that great care should be devoted to optimize the collecting power and the energy resolution of the whole system.

Filaments and membranes in the mitotic apparatus

1983 ◽  
Vol 41 ◽  
pp. 544-547
Author(s):  
Kent McDonald
Keyword(s):  
Intermediate Filaments ◽  
Mitotic Spindle ◽  
Mitotic Apparatus ◽  
Light Microscope Level ◽  
Microtubule Associated Proteins ◽  
Recent Developments ◽  
Associated Proteins ◽  
Force Generator ◽  
Spindle Function ◽  
Antibody Technology

At the light microscope level the recent developments and interest in antibody technology have permitted the localization of certain non-microtubule proteins within the mitotic spindle, e.g., calmodulin, actin, intermediate filaments, protein kinases and various microtubule associated proteins. Also, the use of fluorescent probes like chlorotetracycline suggest the presence of membranes in the spindle. Localization of non-microtubule structures in the spindle at the EM level has been less rewarding. Some mitosis researchers, e.g., Rarer, have maintained that actin is involved in mitosis movements though the bulk of evidence argues against this interpretation. Others suggest that a microtrabecular network such as found in chromatophore granule movement might be a possible force generator but there is little evidence for or against this view. At the level of regulation of spindle function, Harris and more recently Hepler have argued for the importance of studying spindle membranes. Hepler also believes that membranes might play a structural or mechanical role in moving chromosomes.

Software pattern recognition applied to nanodiffraction patterns from a STEM instrument

1986 ◽  
Vol 44 ◽  
pp. 694-695
Author(s):  
G.Y. Fan ◽  
J.M. Cowley
Keyword(s):  
Image Processing ◽  
Pattern Recognition ◽  
Computer Software ◽  
Processing System ◽  
Light Level ◽  
Host Computer ◽  
Low Light ◽  
Image Processing System ◽  
Recent Developments ◽  
On Line

In recent developments, the ASU HB5 has been modified so that the timing, positioning, and scanning of the finely focused electron probe can be entirely controlled by a host computer. This made the asynchronized handshake possible between the HB5 STEM and the image processing system which consists of host computer (PDP 11/34), DeAnza image processor (IP 5000) which is interfaced with a low-light level TV camera, array processor (AP 400) and various peripheral devices. This greatly facilitates the pattern recognition technique initiated by Monosmith and Cowley. Software called NANHB5 is under development which, instead of employing a set of photo-diodes to detect strong spots on a TV screen, uses various software techniques including on-line fast Fourier transform (FFT) to recognize patterns of greater complexity, taking advantage of the sophistication of our image processing system and the flexibility of computer software.

High-resolution microscopy of twin boundaries in gold

1987 ◽  
Vol 45 ◽  
pp. 260-261
Author(s):  
William Krakow ◽  
David A. Smith
Keyword(s):  
High Resolution ◽  
Specimen Preparation ◽  
Gold Films ◽  
Boundary Area ◽  
Transmission Electron ◽  
Recent Developments ◽  
Tilt Boundaries ◽  
High Resolution Microscopy ◽  
Twist Boundaries

Recent developments in specimen preparation, imaging and image analysis together permit the experimental determination of the atomic structure of certain, simple grain boundaries in metals such as gold. Single crystal, ∼125Å thick, (110) oriented gold films are vapor deposited onto ∼3000Å of epitaxial silver on (110) oriented cut and polished rock salt substrates. Bicrystal gold films are then made by first removing the silver coated substrate and placing in contact two suitably misoriented pieces of the gold film on a gold grid. Controlled heating in a hot stage first produces twist boundaries which then migrate, so reducing the grain boundary area, to give mixed boundaries and finally tilt boundaries perpendicular to the foil. These specimens are well suited to investigation by high resolution transmission electron microscopy.

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