1. The exercise is great; the lifting gets easier with every load, even if my shoulder muscle is sore.
    这可锻炼人哩，虽然肩部肌肉酸痛，可我扛垃圾桶越扛越得心应手了。

2. ´Rest´, in terms of muscle relaxation and so on,
    "休息"，从使肌肉得到放松等方面来看，

3. "We've done years of work in showing that excess alarm or stress chemicals can literally burst heart muscle fibers.
    "我们已经做了多年研究，证明过分忧虑或紧张所产生的化学物质的确会损伤心肌纤维。

4. An embryo is an early stage of development in which cells are busy dividing and "transforming" into specialized cells like skin, eye, or muscle cells.
    胚胎是发育的最初阶段，在这个阶段，细胞不停地分裂并"转化"成特化的细胞，如皮肤细胞、眼睛细胞、或肌肉细胞等。

5. Which is specifically concerned with preventing muscle inactivity.
    以防止肌肉活动停止。

6. Who studied 301 men and women aged 70 and older with at least one risk factor for falling, such as muscle weakness or use of certain medicines.
    她调查了301名70或70岁以上的男女，他们都至少有一种导致摔跤的风险因素，如肌肉无力或使用某些药物等。