ELLERBY, D.J*; SPIERTS, I.L.Y.; ALTRINGHAM, J.D.: Fast muscle function in the European eel (Anguilla anguilla, L.) during aquatic and terrestrial locomotion
Eels are capable both of locomotion in water and on land using undulations of the body axis, powered by the lateral musculature. Differences in kinematics and the underlying patterns of fast muscle activation are apparent between locomotion in these two environments. Fast muscle power outputs were measured using the work loop technique, under conditions that simulated their use during aquatic and terrestrial locomotion. The muscle strain and stimulation parameters associated with swimming generated greater force and power than those associated with terrestrial crawling. This decrease in muscle performance may occur because on land the eel is constrained to a particular kinematic pattern in order to produce thrust against an underlying substrate. Muscle properties changed along the body axis as reported in other teleost fish. Maximum power outputs using optimal strain and stimulation parameters were 17.3 � 1.3 Wkg-1 in muscle from 0.45 BL (body lengths from the snout) and 16.3 � 1.5 Wkg-1 in muscle from 0.75 BL. Time from stimulus to peak force Ta was 82 � 6 ms at 0.45 BL and 93 � 3 ms at 0.75 BL. Time from stimulus to 90 % relaxation T90 was 190 � 13 ms at 0.45 BL and 228 � 11 ms at 0.75 BL.