Physiological efficiency of constant power output at varying pedal rates

Merrill, E.G.; White, John Albert

doi:10.1080/02640418408729693

Cited by 10 publications

(6 citation statements)

References 17 publications

(30 reference statements)

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“…Our values for work efficiency on the cycle ergometer were close to those reported by other authors. A number of studies have reported work efficiency to be in the range 20-26% (Andersen and Saltin, 1985;Asmussen and BondePetersen, 1974;Davis et al, 1982;Henry and Demoor, 1950;Merrill and White, 1984;Stuart et al, 1981;Suzuki, 1979).…”

Section: Discussionmentioning

confidence: 99%

Ventilatory threshold and work efficiency during exercise on a cycle and rowing ergometer

Bunc

Leso

1993

Journal of Sports Sciences

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The purpose of this investigation was to determine the effects of increasing specific (rowing ergometer) and non-specific (cycle ergometer) workloads on parameters relating to the ventilatory threshold (Tvent) and work efficiency. When highly trained male rowers were tested using non-specific workloads, their %VO2 max values at Tvent were close to those characteristic of untrained subjects (74.6 +/- 6.2% VO2 max). However, when we tested the same subjects using specific workloads, we recorded values typical of highly trained athletes (85.0 +/- 4.4% VO2 max). For the non-specific exercise on the cycle ergometer, we recorded work efficiency values close to those of untrained subjects (22.8 +/- 2.1%); however, for the specific exercise on the rowing ergometer, we recorded much lower values (16.4 +/- 3.1%). Because of the results of the non-specific submaximal exercise tests, we suggest caution in the interpretation of physiological variables that may be sensitive to training status. The evaluation of Tvent and work efficiency as supplementary parameters during laboratory studies will enable researchers to ascertain the effectiveness of the training process used, as well as indicating the specificity of the loading apparatus.

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Section: Discussionmentioning

confidence: 99%

Ventilatory threshold and work efficiency during exercise on a cycle and rowing ergometer

Bunc

Leso

1993

Journal of Sports Sciences

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“…Powers et al (1984) have shown that gross efficiency increases as a function of power output, but decreases as a function of speed of movement in arm cranking. Merrill and White (1985) showed a decreasing metabolic economy with increasing pedalling rate in simulated racing cycling. A reasonable extension of these works would be to examine the riders' response to variations in cadence and power output by examining the associated pedal forces.…”

Section: Introductionmentioning

confidence: 92%

“…Banister and Jackson, 1967;Seabury et al, 1977;Merrill and White, 1985). Coast and Welch (1985) have shown that for equivalent power outputs, there is a minimal energy expenditure, as measured by oxygen uptake, associated with a specific pedal rate (rev min~1).…”

Section: Introductionmentioning

confidence: 99%

The influence of cadence and power output on the biomechanics of force application during steady‐rate cycling in competitive and recreational cyclists

Sanderson

1991

Journal of Sports Sciences

110

106

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The intent of this study was two-fold. The first aim was to investigate how cyclists orient forces applied by the feet to the pedals in response to varying power output and cadence demands, and the second was to assess whether competitive riders responded differently from recreational riders to such variations. One group consisted of US Cycling Federation category II licensed competitive cyclists (n = 7) and the second group consisted of recreational cyclists with no competitive experience (n = 38). The subjects rode an instrumented stationary 10-speed geared bicycle mounted on a platform designed to provide rolling and inertial resistance for six pedal rate/power output conditions for a minimum of 2 min for each ride. The pedalling rates were 60, 80 and 100 rev min-1 and the power outputs 100 and 235 W. All rides were presented in random order. The forces applied to the pedals, the pedal angle with respect to the crank and the crank angle were recorded for the final 30 s of each ride. From these data, a number of variables were computed including peak normal and tangential forces, crank torque, angular impulse, proportion of resultant force perpendicular to the crank, and pedal angle. Both the competitive and recreational groups responded similarly to increases in cadence and power output. There was a decrease in the peak normal forces, whereas the tangential component remained almost constant as cadence was increased. Regardless of cadence, the riders responded to increased power output demands by increasing the amount of positive angular impulse. All the riders had a reduced index of effectiveness as cadence increased. This was found to be the result of the large effect of the forces during recovery on this calculation. There were no significant differences between the two groups in each of these variables over all conditions. It was concluded that the lack of difference between the groups was a combined consequence of the limited degrees of freedom associated with the bicycle and that the relatively low power output for the competitive riders was insufficient to discriminate or highlight superior riding technique.

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“…One can maintain a constant power output even when speed is varied. However, despite an unchanging power output, a change in speed and thus force has been shown to affect many physiological responses including metabolic efficiency, [1][2][3][4][5][6][7] oxygen deficit, 8 lactate threshold, 9 and aerobic capacity. 8 Much of the pertinent literature has been related to movement economy or athletic performance.…”

mentioning

confidence: 99%

Effect of contraction frequency on energy expenditure and substrate utilisation during upper and lower body exercise

Kang

Hoffman²,

Wendell³

et al. 2004

Br J Sports Med

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Objective: To examine the effect of contraction frequency on energy expenditure and substrate utilisation during upper (UE) and lower (LE) body exercise. Methods: Twenty four college students were recruited: 12 were tested on an arm ergometer, and the other 12 were tested on a leg ergometer. Each subject underwent three experimental trials on three separate days, and the three trials were presented in a randomised order. Each trial consisted of 10 minutes of arm cranking or leg cycling at 40, 60, or 80 rev/min, with power output being kept constant at 50 W. Steady state oxygen uptake (VO 2 ) and respiratory exchange ratio (RER) were measured during each exercise. Energy expenditure was calculated from the steady state VO 2 adjusted for substrate metabolism using RER. Carbohydrate and fat oxidation were calculated from VO 2 and RER based on the assumption that protein breakdown contributes little to energy metabolism during exercise. Results: Energy expenditure was greater (p,0.05) at 80 rev/min than at 40 rev/min. No difference was found between 40 and 60 rev/min and between 60 and 80 rev/min during both UE and LE. During LE, carbohydrate oxidation was also higher at 80 rev/min than at 40 rev/min, whereas no difference in fat oxidation was found among all three pedal rates. During UE, no speed related differences in either carbohydrate or fat utilisation were observed. Conclusions: Pedalling at a greater frequency helped to maximise energy expenditure during exercise using UE or LE despite an unchanging power output. Whereas contraction frequency affects energy expenditure similarly during both UE and LE, its impact on carbohydrate utilisation appears to be influenced by exercise modality or relative exercise intensity. P ower output of any given activity is determined by both the speed at which movement takes place and the force that is generated by the exercising muscle. One can maintain a constant power output even when speed is varied. However, despite an unchanging power output, a change in speed and thus force has been shown to affect many physiological responses including metabolic efficiency, [1][2][3][4][5][6][7] oxygen deficit, 8 lactate threshold, 9 and aerobic capacity. 8Much of the pertinent literature has been related to movement economy or athletic performance. Whether a change in speed would affect patterns of energy expenditure and substrate utilisation has not been thoroughly investigated. This is an intriguing question given that some commonly used exercise ergometers are equipped with a servo mechanism with which speed of movement can be selected without a concurrent change in workload. Cycling at a higher pedal rate has been considered to not only recruit more motor units, but also elicit a higher concentration of blood lactate despite an unchanging workload. 9 In this context, it may be speculated that more energy would be expended and carbohydrate used if exercise were performed at a fast velocity concomitant with less muscular tension. This hypothesis, however, remains to be tested, as Ha...

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Physiological efficiency of constant power output at varying pedal rates

Cited by 10 publications

References 17 publications

Ventilatory threshold and work efficiency during exercise on a cycle and rowing ergometer

Ventilatory threshold and work efficiency during exercise on a cycle and rowing ergometer

The influence of cadence and power output on the biomechanics of force application during steady‐rate cycling in competitive and recreational cyclists

Effect of contraction frequency on energy expenditure and substrate utilisation during upper and lower body exercise

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