Electrically conditioned skeletal muscle can provide the continuous power source for cardiac assistance devices. Optimization of the available sustained power from in vivo skeletal muscle requires knowledge of its metabolic utilization and constraints. A thermistor-based technique has been developed to measure temperature changes and to provide a relative estimate for metabolic utilization of in situ rabbit soleus muscle. The relative thermistor response, active tension and muscle displacement were measured during cyclic isometric and isotonic contractions across a range of muscle tensions and contraction durations. The thermistor response demonstrated linear relationships versus both contraction duration at a fixed muscle length and active tension at a fixed contraction duration (r(2)=0.90+/−0.14 and 0.70+/−0.21, respectively; means +/− s.d.). A multiple linear regression model was developed to predict normalized thermistor response, DeltaT, across a range of conditions. Significant model variables were identified using a backward stepwise regression procedure. The relationships for the in situ muscles were qualitatively similar to those reported for mammalian in vitro muscle fiber preparations. The model had the form DeltaT=C+at(c)F+bW, where the constant C, and coefficients for the contraction duration t(c) (ms), normalized active tension F and normalized net work W were C=−1.00 (P<0.001), a=5.97 (P<0.001) and b=2.12 (P<0.001).

REFERENCES

Barclay
C. J.
,
Curtin
N. A.
,
Woledge
R. C.
(
1994
).
Efficiency of fast-and slow-twitch muscles of the mouse performing cyclic contractions
.
J. Exp. Biol
193
,
65
–.
Curtin
N. A.
,
Howarth
J. V.
,
Woledge
R. C.
(
1983
).
Heat production by single fibres of frog muscle
.
J. Muscle Res. Cell Motil
4
,
207
–.
Curtin
N. A.
,
Woledge
R. C.
(
1993
).
Efficiency of energy conversion during sinusoidal movement of white muscle fibres from the dogfish Scyliorhinus canicula
.
J. Exp. Biol
183
,
137
–.
Gibbs
C. L.
,
Gibson
W. R.
(
1972
).
Energy production of rat soleus muscle
.
Am. J. Physiol
223
,
864
–.
Holroyd
S. M.
,
Gibbs
C. L.
,
Luff
A. R.
(
1996
).
Shortening heat in slow-and fast-twitch muscles of the rat
.
Am. J. Physiol
270
,
293
–.
Homsher
E.
,
Mommaerts
W. F.
,
Ricchiuti
N. V.
(
1973
).
3674Energetics of shortening muscles in twitches and tetanic contractions. II. Force determined shortening heat
.
J. Gen. Physiol
62
,
677
–.
Kobayashi
T.
,
Shimo
M.
,
Sugi
H.
(
1998
).
Infrared thermography of bullfrog skeletal muscle at rest and during an isometric tetanus
.
Jap. J. Physiol
48
,
477
–.
Lou
F.
,
Curtin
N.
,
Woledge
R.
(
1997
).
The energetic cost of activation of white muscle fibers from the dogfish Scyliorhinus canicula
.
J. Exp. Biol
200
,
495
–.
Mommaerts
W. F.
(
1969
).
Energetics of muscle conraction
.
Physiol. Rev
49
,
427
–.
Reichenbach
S. H.
,
Farrar
D. J.
(
1994
).
Characterization andwork optimization of skeletal muscle as a VAD power source
.
ASAIO J
40
,
359
–.
Reichenbach
S. H.
,
Farrar
D. J.
,
Hill
J. D.
(
1995
).
Effects of contraction duration on power for a skeletal muscle driven VAD
.
ASAIO J
24
,
57
–.
Reichenbach
S. H.
,
Farrar
D. J.
,
Hill
J. D.
(
1999
).
Passive characteristics of conditioned skeletal muscle for ventricular assistance
.
ASAIO J
45
,
344
–.
Salmons
S.
,
Henriksson
J.
(
1981
).
The adaptive response of skeletal muscle to increase use
.
Muscle Nerve
4
,
94
–.
Saugen
E.
,
Vollestad
N. K.
(
1995
).
Nonlinear relationship between heat production and force during voluntary contractions in humans
.
J. Appl. Physiol
79
,
2043
–.
This content is only available via PDF.