Abstract
Muscle produces force by forming cross-bridges, using energy released from ATP. While the magnitude and duration of force production primarily determine the energy requirement, nearly a century ago Fenn observed that muscle shortening or lengthening influenced energetic cost of contraction. When work is done by the muscle, the energy cost is increased and when work is done on the muscle the energy cost is reduced. However, the magnitude of the 'Fenn effect' and its mirror ('negative Fenn effect') have not been quantitatively resolved. We describe a new technique coupling magnetic resonance spectroscopy with an in vivo force clamp that can directly quantify the Fenn effect [E=I+W, energy liberated (E) equals the energy cost of isometric force production (I) plus the work done (W )] and the negative Fenn effect (E=I-W ) for one muscle, the first dorsal interosseous (FDI). ATP cost was measured during a series of contractions, each of which occurred at a constant force and for a constant duration, thus constant force-time integral (FTI). In all subjects, as the FTI increased with load, there was a proportional linear increase in energy cost. In addition, the cost of producing force greatly increased when the muscle shortened, and was slightly reduced during lengthening contraction. These results, though limited to a single muscle, contraction velocity and muscle length change, do quantitatively support the Fenn effect. We speculate that they also suggest that an elastic element within the FDI muscle functions to preserve the force generated within the cross-bridges.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2075-2082 |
| Number of pages | 8 |
| Journal | Journal of Experimental Biology |
| Volume | 218 |
| Issue number | 13 |
| DOIs | |
| State | Published - Jul 1 2015 |
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Keywords
- P MRS
- First dorsal interosseous
- Muscle energetics
- Muscle mechanics
ASJC Scopus subject areas
- Animal Science and Zoology
- Ecology, Evolution, Behavior and Systematics
- Molecular Biology
- Physiology
- Insect Science
- Aquatic Science
Cite this
Muscle force, work and cost : A novel technique to revisit the Fenn effect. / Ortega, Justus O.; Lindstedt, Stan L; Nelson, Frank E.; Jubrias, Sharon A.; Kushmerick, Martin J.; Conley, Kevin E.
In: Journal of Experimental Biology, Vol. 218, No. 13, 01.07.2015, p. 2075-2082.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Muscle force, work and cost
T2 - A novel technique to revisit the Fenn effect
AU - Ortega, Justus O.
AU - Lindstedt, Stan L
AU - Nelson, Frank E.
AU - Jubrias, Sharon A.
AU - Kushmerick, Martin J.
AU - Conley, Kevin E.
PY - 2015/7/1
Y1 - 2015/7/1
N2 - Muscle produces force by forming cross-bridges, using energy released from ATP. While the magnitude and duration of force production primarily determine the energy requirement, nearly a century ago Fenn observed that muscle shortening or lengthening influenced energetic cost of contraction. When work is done by the muscle, the energy cost is increased and when work is done on the muscle the energy cost is reduced. However, the magnitude of the 'Fenn effect' and its mirror ('negative Fenn effect') have not been quantitatively resolved. We describe a new technique coupling magnetic resonance spectroscopy with an in vivo force clamp that can directly quantify the Fenn effect [E=I+W, energy liberated (E) equals the energy cost of isometric force production (I) plus the work done (W )] and the negative Fenn effect (E=I-W ) for one muscle, the first dorsal interosseous (FDI). ATP cost was measured during a series of contractions, each of which occurred at a constant force and for a constant duration, thus constant force-time integral (FTI). In all subjects, as the FTI increased with load, there was a proportional linear increase in energy cost. In addition, the cost of producing force greatly increased when the muscle shortened, and was slightly reduced during lengthening contraction. These results, though limited to a single muscle, contraction velocity and muscle length change, do quantitatively support the Fenn effect. We speculate that they also suggest that an elastic element within the FDI muscle functions to preserve the force generated within the cross-bridges.
AB - Muscle produces force by forming cross-bridges, using energy released from ATP. While the magnitude and duration of force production primarily determine the energy requirement, nearly a century ago Fenn observed that muscle shortening or lengthening influenced energetic cost of contraction. When work is done by the muscle, the energy cost is increased and when work is done on the muscle the energy cost is reduced. However, the magnitude of the 'Fenn effect' and its mirror ('negative Fenn effect') have not been quantitatively resolved. We describe a new technique coupling magnetic resonance spectroscopy with an in vivo force clamp that can directly quantify the Fenn effect [E=I+W, energy liberated (E) equals the energy cost of isometric force production (I) plus the work done (W )] and the negative Fenn effect (E=I-W ) for one muscle, the first dorsal interosseous (FDI). ATP cost was measured during a series of contractions, each of which occurred at a constant force and for a constant duration, thus constant force-time integral (FTI). In all subjects, as the FTI increased with load, there was a proportional linear increase in energy cost. In addition, the cost of producing force greatly increased when the muscle shortened, and was slightly reduced during lengthening contraction. These results, though limited to a single muscle, contraction velocity and muscle length change, do quantitatively support the Fenn effect. We speculate that they also suggest that an elastic element within the FDI muscle functions to preserve the force generated within the cross-bridges.
KW - P MRS
KW - First dorsal interosseous
KW - Muscle energetics
KW - Muscle mechanics
UR - http://www.scopus.com/inward/record.url?scp=84955458703&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84955458703&partnerID=8YFLogxK
U2 - 10.1242/jeb.114512
DO - 10.1242/jeb.114512
M3 - Article
VL - 218
SP - 2075
EP - 2082
JO - Journal of Experimental Biology
JF - Journal of Experimental Biology
SN - 0022-0949
IS - 13
ER -