Many kinesiologists talk about ‘energy’. Sometimes they mean the usual definition of this – action, force, vigour, but more commonly it is short for subtle energy.
The Concise Oxford Dictionary defines subtle as: ‘tenuous or rarefied…. evasive, mysterious, hard to grasp or trace… making fine distinctions’. Subtle energy is a loose term used to describe any energy that is not specifically recognized and categorized by conventional scientific knowledge.
In her book Energy Medicine Donna Eden describes this energy as:   … the common medium of the body, mind and soul. Its wavelengths, rates of vibration, and patterns of pulsation form their shared vocabulary.
Just as the body has a physical system, it is understood by Chinese Medicine and Ayurvedic practitioners to have a subtle energy system, not recognised in general by science and medicine. The subtle energy system interacts with the physical body, but its essence is vibrational rather than physical. Other subtle energy concepts include subtle bodies, chakras, nadis and, most importantly for an understanding of kinesiology, meridians. 
Some kinesiologies (such as Integrated Healing) work explicitly and extensively with the subtle energy system, whereas others (for example Applied Kinesiology) focus on working with meridians.