Meeting Abstract
P3.194 Sunday, Jan. 6 The effect of eccentric exercise on whole animal performance and muscle properties. CORCORAN, MA*; PACE, CM; FUQUA, RD; NISHIKAWA, KC; Northern Arizona University michele.corcoran@coconino.edu
Animals performing vertical jumps are thought to utilize elastic structures to store energy and increase jump height. Additionally, eccentric (lengthening) muscle contractions may provide additional elastic recoil energy and have been suggested to play a role in jumping. Eccentric exercise may affect structures in muscle that contribute to elastic recoil, such as titin. Therefore, we asked whether eccentric exercise changes animal performance (in this case vertical jumping) and whether corresponding changes could occur in the muscle properties that are attributable to titin? Eccentric exercise training was performed on mice using a downhill treadmill. The mice were trained every day for a maximum of 30 minutes for 5 weeks, walking at a speed of 18 cm/sec at downhill angles starting at -16° and increasing to -28°. At the end of the training period, maximal jumps were elicited from the mice. The highest jump for each mouse was recorded using a high speed camera and jump height was measured. Jumping data were also collected from a control group of mice who had never been exercised. After jumping, mice from both groups were euthanized and active and passive stiffness was measured from the soleus muscle using a servomotor force lever. There was no difference in jump height between the exercised and non-exercised groups of mice. However, the soleus muscle from exercised mice exhibited greater passive stiffness, although maximum isometric force was similar between the two groups. These data suggest that, although there wasn’t an overall performance difference, the eccentric training affected the muscle properties of the mice. In particular, because passive muscle stiffness increased after eccentric training, it appears that this training affected titin based muscle stiffness in the mice.
