Influence of an Inspiratory Muscle Fatigue Protocol on Older Adults on Respiratory Muscle Strength, Muscle Oxygen Saturation, and Functional Capacity

Respiratory muscle training represents an effective method increasingly utilized in both sports and healthcare domains, employing various devices, among which threshold devices are prominent. The aim of this study is to determine the relationship between diaphragmatic fatigue and muscular strength in upper and lower limbs, in both healthy and pathological subjects, as well as the association between such fatigue and other variables, including maximal inspiratory pressure, functionality and muscle tissue oxygen levels.

According to our hypothesis, the execution of a protocol inducing diaphragmatic fatigue in older adults could influence muscular strength, cardiorespiratory function, exercise capacity, and muscle tissue oxygenation.

In this study, subjects will be divided into three groups: the experimental group , the activation group and the control group.

Measurements of variables, such as maximal inspiratory pressure, peripheral muscle tissue oxygen levels, diaphragmatic strength (ultrasound image) and functional capacity, will be conducted.

this is a randomized control trial. The experimental group (EG) will perform the diaphragmatic fatigue protocol using a specific inspiratory endurance test, in which volunteers, one-on-one, and in a single session, will breathe against submaximal inspiratory loads equivalent to 60% of their Maximum Inspiratory Pressure (MIP) through a threshold valve device. The participants will follow a free pattern of breathing until they are unable to establish flow during at least 3 maximum inspiratory efforts.

The activation group (AG) will perform the protocol of 2 sets of 30 repetitions at 15% of their MIP, one-on-one, and in a single session, using a threshold valve device.

The control group will do a seat and wait.

The interventions will be supervised by a physiotherapist. The primary outcomes will be

* Muscle oxygen saturation (SmO2) will be assessed using a near infrared spectroscopy device, immediately before intervention and immediately after intervention
* Functional mobility will be assessed using the Timed Up and Go Test (TUG) immediately before intervention and immediately after intervention
* Respiratory muscle strength will be assessed using a respiratory pressure meter or manometer designed, and with ultrasound image measuring the cross sectional area of the diaphragm at 8-9th rib level and speed of contraction with a deep and fast inspiratory manoeuver. This will be done immediately before intervention and immediately after intervention
* Functional capacity will be assessed using the Five sit to Stand Test (5STS) Immediately before intervention and immediately after intervention.

Eligibility Criteria:
Inclusion Criteria:

* • Being over 60 years old.

  * Physical independence in terms of gait and transfers

Exclusion Criteria:

* Having any pathology that prevents the performance of physical activity.

  * Subjects with impaired cognitive abilities.
  * Subjects with tympanic perforation or middle-inner ear pathology.
  * Subjects with pulmonary hypertension, decompensated heart or respiratory failure.
  * Subjects who have undergone lower limb surgery within the past 12 months.