本文是一篇说明文。文章主要讲的是锻炼对于心脏的好处。

【长难句分析】

But the study was small and needs to be repeated with far larger groups of people to determine exactly which aspects of an exercise routine make the biggest difference.

分析：本句的主干为But the study was small and needs to be repeated。with far larger groups of people为介词短语作方式状语，to determine...the biggest difference为不定式短语作目的状语，其中which引导宾语从句作determine的宾语。

译文：但这项研究的规模很小，需要在更大的人群中重复进行，以确定日常锻炼的哪些方面会产生最大的影响。

【语块积累】

process v. 加工，处理 oxygen n. 氧气

drawer n. 抽屉 high-intensity adj. 高强度的

rubber band 橡皮筋 show up 出现

in midlife 人到中年 get/keep in shape 健身

make a big difference 有影响，起重要作用（make the biggest difference）