Adenosine triphosphate (ATP) is a molecule that carries energy into and out of cells. Moreover, it is critical in muscle contraction and relaxation as it prepares the myosin for binding and recharges it (Libretexts, 2022). Thus, a muscle is contracted when the ATP molecule activates myosin heads through the energy supply. On the other hand, muscle relaxation occurs when ATP contributes to the disconnection between the aforementioned myosin heads and actin filaments. Thus, in the case there is a lack of ATP, muscles would stay contracted without being able to relax or relax if it was their initial state.
The sternocleidomastoids are the biggest pair of muscles in the neck. Their function is head rotation and flexing. Thus, the range of motion would majorly be affected if one lacked a sternocleidomastoid. For example, researchers mention that individuals who address issues with this particular muscle are able to better rotate their head left and right as well as maximize their lateral flexion (Büyükturan et al., 2021). Thus, in case the muscle would not present, a person would not be able to exercise activities such as rotation and flexion to one side, depending on the muscle that is lacking.
Heat and cold have different effects if applied to an injured ankle, which is why the two techniques are employed under contrasting circumstances. An ankle injury, in particular, would require a cold compress in the first days and a hot one in the following days. During the initial stage, cold can be applied to minimize swelling as blood vessels are constricted (Min et al., 2021). In the following days, a contrasting effect is needed, so a hot compress would be applied to maximize blood flow for a maximization of the healing process
References
Büyükturan, B., Şaş, S., Kararti, C., & Büyükturan, Ö. (2021). The effects of combined sternocleidomastoid muscle stretching and massage on pain, disability, endurance, kinesiophobia, and range of motion in individuals with chronic neck pain: A randomized, single-blind study. Musculoskeletal Science and Practice, 55, 102417. Web.
Libretexts. (2022). Muscle contraction and locomotion – ATP and muscle contraction. Biology LibreTexts. Web.
Min, J. Y., Choi, Y. S., Lee, H.S., Lee, S., & Min, K. (2021). Increased cold injuries and the effect of body mass index in patients with peripheral vascular disease. BMC Public Health, 21(1). Web.