Scaling of the Mechanics and Energetics of Mammalian Muscle Fibers with Body Size

小动物的四肢移动的频率比动物高，而且每克小动物比大动物移动一段距离要消耗更多的能量。我们在拨款中提出的问题是，肌肉系统旨在为小动物提供比大动物更多的能量来奔跑？据推测，其潜在的机制在于肌肉纤维的特性。小动物的纤维被认为具有最大缩短速度(Vmax)，这使它们能够更快地缩短，产生力量，并更快地放松--这是它们跑步时高频运动所必需的。但这是有代价的：高V(Max)的纤维使用更多的能量来产生力量，从而潜在地解释了为什么小动物跑步的成本更高。利用我们开发的新技术，我们将通过测量V(Max)和不同类型纤维生成力的能量成本如何在从老鼠到马的哺乳动物中随身体尺寸变化来检验上述假设。

Small animals move their limbs at higher frequencies than animals and it costs more energy per gram for a small animal to move a given distance than for than for a large one. The questions we address in the grant is the muscular system designed to permit much more energy for small animals to run than large ones? It has been hypothesized that the underlying mechanisms lies in the properties of the muscle fibers. The fibers of the small animals are thought to have maximum velocity of shortening (Vmax) which enables them to shorten faster and generate force and relax faster- -a necessity for the high frequencies aty which they run. But there is a price: fibers with high V(max's) use far more energy to generate force, thus potentially explaining why it is more costly for small animals to run. With the new techniques that we have developed, we will test the above hypothesis by measuring how V(max) and the energetic cost of generating force of different fiber types scales with body size in mammals ranging from mice to horses.