WHIPP, BRIAN J., AND KARLMAN WASSERMAN. E@ciency of
muscular work. J. Appl. Physiol. 26(5) : 644-648. 1969.-This
paper discusses the theoretical, thermodynamic basis for exercise
efficiency and describes a modification of the method
used to calculate efficiency. Eight healthy male subjects were
studied during steady-state cycle ergometer work. If the net
02 cost of performing work is obtained by subtracting resting
voz, as is usually done, the work efficiency calculated from the
calorific value for 02 equals 20%. However, if the 02 cost of
“unloaded” cycling is subtracted from the steady-state work
002, the work efficiency calculated from calorific equivalents is
approximately 30%. We consider the latter to be more accurate,
since the 02 cost of moving the legs without a load is
not included in the calculation. Approaching the calculation
of work efficiency thermodynamically, the calculated contraction-coupling
efficiency (E,) is 49 %. If a value of 60% is taken
for phosphorylative-coupling efficiency (Ep) as suggested in
the literature, muscular work efficiency (Em) based on thermodynamic
considerations, is 29oJ,. The term “efficiency” as
used to describe physiological concepts is discussed.