Warm-up of the Inspiratory Musculature and Its Impact in Swimming Performance

After the respiratory interventions, participants will perform a maximal 100-meter freestyle swimming test under supervision. The total time will be recorded using a digital stopwatch, starting with the starting signal and ending when the swimmer touches the wall upon completing the distance.

Maximal Inspiratory Pressure (PIM/MIP) and Maximal Expiratory Pressure (PEM/MEP) are indicators of global respiratory muscle strength. PIM reflects the maximal negative pressure generated during a forced inspiratory effort against an occluded airway, mainly assessing diaphragmatic and external intercostal muscle function, whereas PEM reflects the maximal positive pressure produced during a forced expiratory effort, mainly involving abdominal and internal intercostal muscles. Both variables are expressed in centimeters of water (cmH₂O) and are widely used to quantify inspiratory and expiratory muscle performance, as well as to evaluate respiratory muscle fatigue and training adaptations in clinical and sports settings.

Immediately after the test, blood lactate will be measured using a Lactate Pro 2 portable analyzer, from a capillary blood sample obtained from the fingertip.

Perceived exertion will be assessed using the Borg scale (6-20), previously explained to ensure proper understanding, and will be recorded immediately after exercise through a direct interview.

The Dyspnea-12 (D-12) scale is a multidimensional questionnaire used to assess the severity and qualitative perception of dyspnea (breathlessness). It evaluates both the physical and emotional components associated with breathing discomfort.

The questionnaire consists of 12 items:

My breath does not go in all the way My breathing requires more work I feel short of breath I have difficulty catching my breath I cannot get enough air My breathing is uncomfortable My breathing is exhausting My breathing makes me feel depressed My breathing makes me feel miserable My breathing is distressing My breathing makes me agitated My breathing is irritating

Each item is scored using a 4-point Likert scale:

0 = None

• = Mild
• = Moderate
• = Severe

Therefore, the total score ranges from 0 to 36 points.

Interpretation:

A low score indicates little or no perceived dyspnea. A moderate score reflects clinically relevant breathing discomfort. A high score indicates severe dyspnea with an important

Heart rate will be continuously monitored during the test and for up to five minutes post-exercise using a Polar H10 chest strap, placed on the anterior thoracic region just below the xiphoid process. The device will be calibrated before each session, and data will be analyzed using Polar Flow software to obtain parameters such as mean heart rate, maximum heart rate, which are key indicators of autonomic and cardiovascular response to exercise.

Recovery time will be defined as the period required for heart rate to decrease following the cessation of exercise. This parameter reflects autonomic nervous system recovery, particularly parasympathetic reactivation after physical exertion. Heart rate recovery will be analyzed during the first five minutes post-exercise using data collected from the Polar H10 device. Faster recovery times are generally associated with better cardiovascular fitness and autonomic regulation, whereas delayed recovery may indicate increased physiological stress or fatigue.

Heart rate variability (HRV) refers to the variation in the time intervals between consecutive heartbeats (R-R intervals). HRV is considered a non-invasive marker of autonomic nervous system activity and reflects the balance between sympathetic and parasympathetic modulation. HRV data obtained from the Polar H10 sensor will be analyzed using Polar Flow software, and parameters such as RMSSD and SDNN may be extracted. Higher HRV values are typically associated with better autonomic adaptability and recovery capacity, while lower values may reflect fatigue, stress, or reduced physiological adaptability.

Forced Vital Capacity (FVC/CVF) and Forced Expiratory Volume in 1 second (FEV₁) are spirometric measures used to assess ventilatory capacity and pulmonary function. FVC represents the total volume of air that can be forcibly exhaled after a maximal inspiration, expressed in liters (L), while FEV₁ represents the volume exhaled during the first second of that maneuver, also expressed in liters. The FEV₁/FVC ratio is commonly used to identify ventilatory limitations, particularly obstructive patterns. Together, these variables provide key information on airway function, expiratory flow limitation, and overall pulmonary performance.