About this trial
Objective To evaluate the acute effect of four inspiratory warm-up intensities (15%, 40%, 60%, and 80% of maximal inspiratory pressure \[MIP\]) on 100 m freestyle performance, and to analyze their impact on heart rate, blood lactate concentration, perceived exertion, and dyspnea in trained swimmers.
Methods A randomized, crossover, double-blind experimental study was conducted. Participants were swimmers aged ≥18 years, with no respiratory or musculoskeletal pathology.
Each participant completed, in sessions separated by at least three days, an inspiratory muscle warm-up consisting of 30 breaths against resistive loads set at 15%, 40%, 60%, and 80% of their MIP, previously determined using standardized procedures.
Following each intervention, participants performed a maximal 100 m freestyle test. The following variables were recorded:
Swimming time Heart rate (during and post-exercise) Post-exercise capillary blood lactate concentration Rating of perceived exertion (Borg scale) Dyspnea (Dyspnea-12)
Conclusions This study will help identify the optimal inspiratory warm-up intensity to enhance swimming performance.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
Participants of both sexes, aged over 18 years.
Minimum swimming training frequency of at least two sessions per week, with a minimum duration of 30 minutes per session, consistently maintained over the last three months.
Disqualifiers
Current or previous diagnosis of respiratory diseases.
Musculoskeletal injuries limiting the ability to perform a 100-meter swimming test.
Participation in inspiratory muscle training programs within the last six months.
Trial design
Crossover
Treatments tested in this trial
POWERbreath
DeviceIt is a crossover study in which the different exercise intensities are investigated.
Treatment groups
Trial outcomes
Primary outcomes
swimming time (100 meters)
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.
Secondary outcomes
Maximal Inspiratory Pressure and Maximal Expiratory Pressure
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.
Lactate
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.
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.
Dysnea
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 1. = Mild 2. = Moderate 3. = 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
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