Can isometric exercises preserve independence in seniors with hip fractures?
When a senior person has a hip fracture, there's less than 50% chance of recovery to a pre-fracture level of function. You've probably heard that the survivors quite often end up in nursing homes. Even being active prior to the fracture doesn't offer very much protection. https://www.sciencedaily.com/releases/2016/09/160908120207.htm
Studies show that muscles weaken and atrophy rapidly when immobilized. We're talking about losses in hours or days rather than weeks, months, or even years like in those who became sedentary or former athletes.
A study showed that ICU acquired weaknesses, which may be incurable and lead to a loss of independence, are associated with a loss of satellite cells. Maybe hip fracture patients had a loss of satellite cells as well https://www.sciencedaily.com/releases/2016/04/160408132444.htm
Isometric exercises involve contracting muscles without moving your joints or muscles. That means immobilized muscles can still be exercised.
Would they be enough to prevent a permanent loss of independence like in seniors who fractured their hips?
Is it possible that we don't aggressively and promptly push the exercise program because we're ignorant of the possibility of preventing a loss of independence?
- Patients may not know how to activate all of their muscles. At certain positions, some muscles may be easier to activate than others. For example, you may find it easier to flex your gastrocnemius muscles with your legs straight than with your knees bent.
- Patients may need to be trained how to activate all of their target muscle groups at the right intensity. Even very sedentary individuals may have full recruitment at least for a brief time multiple times a day, possibly protecting against a loss of muscle mass.
- The therapist may not be able to tell whether the right muscle groups were activated or if there was 100% muscle recruitment.
- It's possible that the protection is limited to activated muscle fibres. That means if the exertion was at less than 85% of one rep max, the largest motor units could lose their satellite cells while those of the smaller motor units may be spared. This can decrease maximum strength since there's effectively fewer muscle fibres, and decrease endurance since larger motor units are recruited later in exhaustive exercises.
- Patients have to consciously activate their muscles. For example, our foot muscles, and muscles that moves our legs and feet sideways subconsciously get used when walking but leg curls and extensions may not properly activate them. If those postural muscles are permanently weakened, it can increase the susceptibility to injuries through poor form, and cause balance issues.
A Study that suggests that isometric exercises can help. Electrical stimulation at 20 Hz in mice for 3h can suppress satellite cell apoptosis when immobilized. This seems like isometric than concentric or eccentric exercise but much longer. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257250/
Other possible applications