…when one muscle is highly active, its antagonist muscle is less active and vice versa. This phenomenon is referred to as reciprocal inhibition. As an example, if a singer has engaged in an extended period of singing at high intensity in the chest register (TA is highly active relative to its partner, the CT muscle), it makes sense to engage the opposite register as part of the vocal cool-down. Therefore, light vocalization in head register, where CT is highly active relative to TA, in a descending pattern all the way down into the low range will facilitate relaxation of the TA muscle and help return the voice to a more neutral default setting. Conversely, if working extensively in the head register for an extended period of time, the vocal cool-down routine should also include some light chest register.

LeBorgne, Wendy D., PhD, CCC-SLP,  Rosenberg, Marci, MS, CCC-SLP. The Vocal Athlete: Application and Technique for the Hybrid Singer. Plural Publishing, 2014.