Chemical and Mechanical Changes during Stretching of Activated Frog Skeletal Muscle

Curtin, N. A.; Davies, R. E.

doi:10.1101/sqb.1973.037.01.074

Cited by 102 publications

(64 citation statements)

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“…When the same muscle is stretched, however, both the rate of metabolic heat production Wilkie, 1968) and of ATP and creatine phosphate break-down (Marechal, 1964;Wilkie, 1968) are markedly suppressed below the isometric value in spite of the high tensions these fibres can exert. Some authors have found values close to zero (Hill & Howarth, 1959;Curtin & Davies, 1970). This suggests that much larger differences in the rate of oxygen consumption per unit muscle fibre activity might well have been found in the present experiments.…”

Section: Discussionsupporting

confidence: 69%

“…These results are generally explained solely in terms of the differences in the number of actively contracting muscle fibres that are required in each work mode (Abbott & Bigland, 1953): according to the force/velocity relationship for muscle (Hill, 1938), each individual fibre can exert a larger force while being stretched than while shortening (Katz, 1939), so fewer fibres are required to exert any given force. However, it is clear from isolated muscle studies' B. BIGLAND-RITCHIE AND J. J. IVOODS that when a muscle is stretched the energy requirement of the fibre, measured from both its rate of metabolic heat production and its rates of ATP and phosphocreatine break-down, falls substantially (Wilkie, 1968;Curtin & Davies, 1970).…”

Section: Introductionmentioning

confidence: 99%

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Integrated electromyogram and oxygen uptake during positive and negative work.

Bigland-Ritchie¹,

Woods²

1976

The Journal of Physiology

263

157

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SUMMARY1. Integrated electromyogram (e.m.g.) from the vastus lateralis muscles, and steady-state rates of oxygen uptake, were measured simultaneously during the performance of set rates of positive (concentric) and negative (eccentric) work at 50 rev/min on a motorized bicycle ergometer.2. Similar experiments were also carried out at other pedalling rates and using other leg muscles.3. The relationships between each of the variables (integrated e.m.g., oxygen consumption) and mean torque on pedals were found to be lineal (r > 0-98) with a remarkable degree of reproducibility in surface e.m.g. for each subject over several months.4. The ratio of the e.m.g. slopes at 50 rev/min (positive/negative) was 1-96 + 0-12 while the same ratio for the oxygen uptake slopes was 6-34 + 0-82. The discrepancy between the ratios suggests that not only is less muscle fibre activity required to maintain the same exerted force during negative work exercise, but there is also a substantial reduction in the oxygen uptake when the fibres are stretched. This was observed for all speeds of pedalling.

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Section: Discussionsupporting

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Integrated electromyogram and oxygen uptake during positive and negative work.

Bigland-Ritchie¹,

Woods²

1976

The Journal of Physiology

263

157

View full text Add to dashboard Cite

show abstract

“…I The drastic fall in energy liberation when a muscle is stretched during contraction has been repeatedly confirmed both by myothermal methods (Abbott, Aubert & Hill, 1951;Abbott & Aubert, 1951;Hill & Howarth, A. F. HUXLEY 8 MUSCULAR CONTRACTION 1959;Wilkie, 1968) and by measurement of phosphorylcreatine utilization (Wilkie, 1968) and appearance of inorganic phosphate (Curtin & Davies, 1973). It is not yet clear whether the net energy liberation in a complete twitch can drop to zero, as suggested by the results of Hill & Howarth (1959) or whether there is always a residual energy liberation at least equal to the 'activation heat'.…”

Section: The Mechanism Of Contractionmentioning

confidence: 93%

Muscular contraction.

Huxley¹

1974

The Journal of Physiology

700

340

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“…1A). However, when muscle is lengthened while active, it will produce high forces (Katz, 1939), and require little metabolic energy (Curtin and Davies, 1973;Beltman et al, 2004), thus the cost of force production during the lengthening portion of the cycle in Fig. 1B will be low.…”

Section: Introductionmentioning

confidence: 99%

The energetic benefits of tendon springs in running: is the reduction of muscle work important?

Holt

Roberts

Askew

2014

Journal of Experimental Biology

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The distal muscle-tendon units of cursorial species are commonly composed of short muscle fibres and long, compliant tendons. It is assumed that the ability of these tendons to store and return mechanical energy over the course of a stride, thus avoiding the cyclic absorption and regeneration of mechanical energy by active muscle, offers some metabolic energy savings during running. However, this assumption has not been tested directly. We used muscle ergometry and myothermic measurements to determine the cost of force production in muscles acting isometrically, as they could if mechanical energy was stored and returned by tendon, and undergoing active stretch-shorten cycles, as they would if mechanical energy was absorbed and regenerated by muscle. We found no detectable difference in the cost of force production in isometric cycles compared with stretch-shorten cycles. This result suggests that replacing muscle stretch-shorten work with tendon elastic energy storage and recovery does not reduce the cost of force production. This calls into question the assumption that reduction of muscle work drove the evolution of long distal tendons. We propose that the energetic benefits of tendons are derived primarily from their effect on muscle and limb architecture rather than their ability to reduce the cyclic work of muscle.

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Chemical and Mechanical Changes during Stretching of Activated Frog Skeletal Muscle

Cited by 102 publications

References 0 publications

Integrated electromyogram and oxygen uptake during positive and negative work.

Integrated electromyogram and oxygen uptake during positive and negative work.

Muscular contraction.

The energetic benefits of tendon springs in running: is the reduction of muscle work important?

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