Physiological and metabolic implications of optimization protocols during high-intensity cycle ergometry: body mass or body composition?

J. Baker, D.M. Bailey, R.R. Morgan, B. Davies

Research output: Contribution to journalMeeting Abstract

Abstract

High-intensity exercise tests are designed to measure maximal power output (Dotan and Bar-Or, 1983: European Journal of Applied Physiology, 51, 409±417). The determination of individual resistive force has been obtained by multiplication of body mass by 75 g ´kg-1. This method of selecting resistive force may be insufficient to elicit peak performances, and optimization protocols can produce higher peak power outputs. 
Although desirable for the determination of optimal resistive force, an optimization procedure using resistive forces derived from total body mass may not be the best approach. Wilkie (1960: Ergonomics, 3, 1±8) suggested that the external optimal resistive force is closely matched to the capacity of the active muscle tissue. 
We measured power values generated during high-intensity cycle ergometry when the resistive forces were dependent on total body mass or fat free mass. Eighteen apparently healthy male university students volunteered to participate. The study was approved by the university’s ethics committee. Before testing, all participants completed an informed consent form. The participants’ age, body mass, height and percent body fat were 23 ± 2 years, 75 ± 11 kg, 1.75 ± 0.06 m and 12 ± 3% respectively (mean ± s).
Body density was estimated using hydrostatic procedures outlined by Behnke et al. (1974: Evaluation of Body Build and Composition. Englewood Cliffs, NJ: Prentice-Hall). Relative body fat was calculated from body density (Siri, 1956: In Advances in Biological and Medical Physics, edited by J.H. Lawrence and C.A. Tobias. New York: Academic Press). Residual lung volume was estimated using the simplified oxygen rebreathing method (Wilmore et al., 1980: Medicine and Science in Sports and Exercise, 12, 216-218). 
A force velocity test was performed 1 week before the 30 s cycle ergometer test to determine optimal resistive forces for both the total body mass and fat free mass protocols (Jaskolska et al., 1999: International Journal of Sports Medicine, 20, 192-197). Blood lactate concentrations were analysed using an automated electrochemical analyser (Analox PGM7 Champion, London UK). Blood haemoglobin and packed cell volume were also determined to calculate the change in plasma volume in capillary samples (Dill and Costill, 1974: Journal of Applied Physiology, 37, 247-248).
Students’ t-tests were used to identify any differences between physiological and metabolic variables. Differences (P < 0.05) in peak power outputs, peak pedal velocities and resistive forces were found between total body mass and fat free mass (993 ± 114 vs 1020 ± 134 W; 134 ± 8 vs 141 ± 7 rev ´min-1 ; 6 ± 1 vs 5 ± 1 kg, respectively). There were no differences (P > 0.05) in post-exercise blood lactate concentrations recorded between the total body mass and fat free mass protocols (9.0 ± 1.2 vs 9.3 ± 1.4 mmol´l-1).
Increased peak power values suggest that the fat free ass protocol represents a method by which greater peak power can be obtained consistently during high-intensity cycle ergometry with no differences in metabolic stress as measured by blood lactate. The increase in peak power output observed during the fat free mass protocol could indicate that this method of resistive force selection represents a more valid index of ATP-PC activity and muscular efficiency in the initial stages of high-intensity cycle ergometer exercise, compared to protocols that include the fat component of body mass.
Original languageEnglish
Pages (from-to)32-32
Number of pages1
JournalJournal of Sports Sciences
Volume20
Issue number1
DOIs
Publication statusPublished - 2002
Externally publishedYes

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