Exercise efficiency during arm ergometry: effects of speed and work rate

Powers, Scott K.; Beadle, R. E.; Mangum, Michael

doi:10.1152/jappl.1984.56.2.495

Cited by 86 publications

(85 citation statements)

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“…This relationship is in agreement with previous studies on wheelchair propulsion [3][4]16,19]. It can be attributed to a decrease in the relative contribution of resting metabolic rate to the overall En at a given workload [20][21]. If this relationship is extended to the slope of a standard wheelchair ramp of 4° to 5°, the apparent benefits of lever propulsion may be even more significant.…”

Section: Discussionsupporting

confidence: 90%

Mechanical efficiency of two commercial lever-propulsion mechanisms for manual wheelchair locomotion

et al. 2013

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Abstract-The purpose of this study was to (1) evaluate the mechanical efficiency (ME) of two commercially available leverpropulsion mechanisms for wheelchairs and (2) compare the ME of lever propulsion with hand rim propulsion within the same wheelchair. Of the two mechanisms, one contained a torsion spring while the other used a roller clutch design. We hypothesized that the torsion spring mechanism would increase the ME of propulsion due to a passive recovery stroke enabled by the mechanism. Ten nondisabled male participants with no prior manual wheeling experience performed submaximal exercise tests using both lever-propulsion mechanisms and hand rim propulsion on two different wheelchairs. Cardiopulmonary parameters including oxygen uptake (VO 2 ), heart rate (HR), and energy expenditure (En) were determined. Total external power (P ext ) was measured using a drag test protocol. ME was determined by the ratio of P ext to En. Results indicated no significant effect of lever-propulsion mechanism for all physiological measures tested. This suggests that the torsion spring did not result in a physiological benefit compared with the roller clutch mechanism. However, both lever-propulsion mechanisms showed decreased VO 2 and HR and increased ME (as a function of slope) compared with hand rim propulsion (p < 0.001). This indicates that both lever-propulsion mechanisms tested are more mechanically efficient than conventional hand rim propulsion, especially when slopes are encountered.

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Section: Discussionsupporting

confidence: 90%

Mechanical efficiency of two commercial lever-propulsion mechanisms for manual wheelchair locomotion

et al. 2013

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“…Similar trends were found in the literature during sub-maximal exercise (lower than 75% _ V O 2max ) (Gaesser and Brooks 1975;Stuart et al 1981;Boning et al 1984;Coyle et al 1992;Berry et al 1993;Nickleberry and Brooks 1996;Kang et al 1997;Chavarren and Calbet 1999). These authors explained the GE versus power and the NE versus power relationships by the decreasing effect of the unmeasured work that comprises the total energy expenditure, and then by the greater extent of the increase of the numerator than the denominator (Whipp and Wasserman 1969;Powers et al 1984;Kang et al 1997). The trend of the WE to decrease with power output was in agreement with previous results obtained during sub-maximal cycling exercise (Gaesser and Brooks 1975;Stuart et al 1981).…”

Section: Intensity Effects On Mechanical Efficiency Indicessupporting

confidence: 80%

Supra-maximal cycling efficiency assessed in humans by using a new protocol

Mourot¹,

Hintzy

Messonier

et al. 2004

Eur J Appl Physiol

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This study proposed a non-invasive method to determine the gross (GE, no baseline correction), net (NE, resting metabolism as the baseline correction) and work (WE, unloaded cycling as the baseline correction) efficiencies during cycling at an intensity higher than the maximal aerobic power (MAP). Twelve male subjects performed two exercises consisting of 4 min at 50% MAP followed either by 8 min at 63% MAP or by 8 sequences of 60 s divided into 10 s at 130% MAP and 50 s at 50% MAP (i.e., 63% MAP on average). Oxygen uptake was continuously measured to calculate GE, NE and WE at 50%, 63% and 130% MAP, and the data presented as the means and standard deviations. The GE values were 18.2%, 19.1%, 22.7%, the NE values were 22.4%, 22.8%, 24.3% and the WE values were 34.2%, 31.4% and 27.2% at 50%, 63% and 130% MAP, respectively. The GE and NE increased (P < 0.001) whereas the WE decreased (P < 0.001) with each increment in power output. The GE was lower than the NE (P < 0.001) at 50% and 63% MAP and than the WE (P < 0.001) at all intensities. The NE was lower (P < 0.001) than the WE at 50% and 63% MAP. These results showed that (1) efficiency index values obtained during supra-maximal exercise were consistent with previous proposals and (2) the efficiency-power output relationships were not limited to sub-maximal intensity levels but were confirmed at higher power output.

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“…Total mechanical work divided by energy expended in doing work, where the energy expended is measured by indirect calorimetry (Powers et al, 1984).…”

Section: Exercise Efficiencymentioning

confidence: 99%

High efficiency in human muscle: an anomaly and an opportunity?

Nelson

Ortega

Jubrias

et al. 2011

Journal of Experimental Biology

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SummaryCan human muscle be highly efficient in vivo? Animal muscles typically show contraction-coupling efficiencies <50% in vitro but a recent study reports that the human first dorsal interosseous (FDI) muscle of the hand has an efficiency value in vivo of 68%. We examine two key factors that could account for this apparently high efficiency value: (1) transfer of cross-bridge work into mechanical work and (2) the use of elastic energy to do external work. Our analysis supports a high contractile efficiency reflective of nearly complete transfer of muscular to mechanical work with no contribution by recycling of elastic energy to mechanical work. Our survey of reported contraction-coupling efficiency values puts the FDI value higher than typical values found in small animals in vitro but within the range of values for human muscle in vivo. These high efficiency values support recent studies that suggest lower Ca 2+ cycling costs in working contractions and a decline in cost during repeated contractions. In the end, our analysis indicates that the FDI muscle may be exceptional in having an efficiency value on the higher end of that reported for human muscle. Thus, the FDI muscle may be an exception both in contraction-coupling efficiency and in Ca 2+ cycling costs, which makes it an ideal muscle model system offering prime conditions for studying the energetics of muscle contraction in vivo.

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Exercise efficiency during arm ergometry: effects of speed and work rate

Cited by 86 publications

References 0 publications

Mechanical efficiency of two commercial lever-propulsion mechanisms for manual wheelchair locomotion

Mechanical efficiency of two commercial lever-propulsion mechanisms for manual wheelchair locomotion

Supra-maximal cycling efficiency assessed in humans by using a new protocol

High efficiency in human muscle: an anomaly and an opportunity?

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