Biomedical subjects

C R Kyle

Publications and source records attributed to C R Kyle.

7 recordsLinked to original sources

PubMed1999

Comparing cycling world hour records, 1967-1996: modeling with empirical data.

PURPOSE: The world hour record in cycling has increased dramatically in recent years. The present study was designed to compare the performances of former/current record holders, after adjusting for differences in aerodynamic equipment and altitude. Additionally, we sought to determine the ideal elevation for future hour record attempts. METHODS: The first step was constructing a mathematical model to predict power requirements of track cycling. The model was based on empirical data from wind-tunnel tests, the relationship of body size to frontal surface area, and field power measurements using a crank dynamometer (SRM). The model agreed reasonably well with actual measurements of power output on elite cyclists. Subsequently, the effects of altitude on maximal aerobic power were estimated from published research studies of elite athletes. This information was combined with the power requirement equation to predict what each cyclist's power output would have been at sea level. This allowed us to estimate the distance that each rider could have covered using state-of-the-art equipment at sea level. According to these calculations, when racing under equivalent conditions, Rominger would be first, Boardman second, Merckx third, and Indurain fourth. In addition, about 60% of the increase in hour record distances since Bracke's record (1967) have come from advances in technology and 40% from physiological improvements. RESULTS AND CONCLUSIONS: To break the current world hour record, field measurements and the model indicate that a cyclist would have to deliver over 440 W for 1 h at sea level, or correspondingly less at altitude. The optimal elevation for future hour record attempts is predicted to be about 2500 m for acclimatized riders and 2000 m for unacclimatized riders.

Acclimatization↗

PubMed1999

Racing cyclist power requirements in the 4000-m individual and team pursuits.

PURPOSE: The purpose of this paper is: 1) to present field test data describing the power requirements of internationally competitive individual and team pursuiters, and 2) to develop a theoretical model for pursuit power based upon on these tests. METHODS: In preparing U.S. cycling's pursuit team for the 1996 Atlanta Olympics, U.S. team scientists measured cycling power of seven subjects on the Atlanta track using a crank dynamometer (SRM) at speeds from 57 to 60 kph. By using these field data and other tests, mathematical models were devised which predict both individual and team pursuit performance. The field data indicate the power within a pace line at 60 kph averages 607 W in lead position (100%), 430 W in second position (70.8%), 389 W in third position (64.1%), and 389 W in fourth position (64.0%). A team member requires about 75% of the energy necessary for cyclists riding alone at the same speed. These results compare well with field measurements from a British pursuit team, to recent wind tunnel tests, and to earlier bicycle coast down tests. RESULTS: The theoretical models predict performance with reasonable accuracy when the average power potential of an individual or team is known, or they may be used to estimate the power of pursuit competitors knowing race times. The model estimates that Christopher Boardman averaged about 520 W when setting his 1996, 4000-m individual pursuit record of 4 min 11.114 s and the Italian 4000-m pursuit team averaged about 480 W in setting their record of 4:00.958. Both used the "Superman" cycling position. CONCLUSIONS: These records would be very difficult to break using less aerodynamic riding positions, due to the extraordinarily high power requirements.

Bicycling↗

PubMed1994

Energy and aerodynamics in bicycling.

By modifying bicycle equipment, technique, rider position, or other human factors, the energy required to propel a bicycle at a given velocity can be decreased significantly. Although this article will concentrate on competitive cycling, the information pertains to all types of cycling.

Bicycling↗

PubMed1986

Athletic clothing.

Explore the source record for details and available documents.

Athletic Injuries↗

PubMed1986

The effect of athletic clothing aerodynamics upon running speed.

The purpose of this study was to determine the effect of the wind resistance of athletic clothing upon running speed in sprinting and in distance running. Wind tunnel tests of clothing materials, hair, and shoes show that it is possible to lower the wind resistance of a runner from about 0.5% to over 6% by improved aerodynamics. Mathematical models of sprinting and distance running are developed to predict the effect of lower wind resistance upon race times. By lowering the wind resistance of a runner 2%, the models predict the effect of lower wind resistance upon race times. By lowering the wind resistance of a runner 2%, the models predict time savings from 0.01 s in the 100-m dash to 5.7 s in the marathon. This is the equivalent of lead distances of about 0.1 to 31 m. The sprint model may be used to predict the effect of altitude upon running speed. At the altitude of Mexico City, the model predicts an improvement of 0.08 s in 100 m and 0.16 s in 200 m. This is conservative compared to actual time savings. The results show that it is possible to lower the wind resistance significantly by improving clothing or by trimming or covering the hair, and that a small aerodynamic drag reduction can result in a significant performance increase.

Air Movements↗

PubMed1985

A comparison of the effect of external loading upon power output in stair climbing and running up a ramp.

Previous studies have shown that external loading increases the power output measured during stair climbing. However, it was noted in an earlier study that stairtreads form mechanical contraints which limit the extent to which a subject can be externally loaded, and, thereby, make it impossible to observe maximal power output for this type of activity. The purpose of this study was to compare the effects of external loading upon power output when running up stairs or a ramp. Since a ramp is free of the mechanical constraints of stairtreads, it was felt that higher power output values would be achieved using the ramp, and that it would be possible to observe an asymptote in power output which could not be obtained for stair climbing. Seven male subjects performed maximal ramp and stair climbing tests under five experimental loading conditions (no external load, 10.1, 19.2, 24.2, and 29.2 kg). For the ramp, it was possible to employ a sixth loading condition of 34.2 kg. For stair climbing, the mean (+/- SD) power output values under the five experimental conditions were 16.6 +/- 0.7, 17.3 +/- 1.3, 18.5 +/- 1.0, 18.6 +/- 1.5, and 18.9 +/- 1.7 W X kg-1, respectively. In contrast, the mean (+/- SD) power output values observed while running up the ramp were 18.8 +/- 1.4, 19.9 +/- 1.6, 20.5 +/- 1.6, 20.1 +/- 2.1, 20.3 +/- 2.1, and 19.8 +/- 1.9 W X kg-1, respectively. At each experimental condition, the differences between the ramp and stairs was significant (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1980

The effect of external loading upon power output in stair climbing.

Previous studies have examined man's ability to produce external power output during maximal repetitive work cycles of short duration. It appears, however, that there were methodological limitations which would inherently mask man's true capacities. Consequently, we examined the effect of variable external loads upon external power output as measured by running upstairs. Fourteen male subjects (16-31 years of age) who regularly participated in competitive sports performed maximal stair step tests under five experimental loading conditions (no external load, 10.1, 19.2, 24.2, and 29.2 kg). Significant increases (P < 0.05) in external power output were found. External power output increased from a mean of 15.9 W x kg-1 +/- 1.0 (unloaded condition) to 18.5 W x kg-1 +/- 1.5 (external load of 29.2 kg). This is the first modern investigation demonstrating that external loads effect external power output as measured by this technique.

Adolescent↗