Effects of Inspiratory Training on Respiratory Function in Swimming

Diaphragm

The diaphragm is the primary muscle of inspiration. It is a dome-shaped skeletal muscle located between the thoracic and abdominal cavities. Its contraction increases thoracic volume, allowing air to enter the lungs. Beyond respiration, it contributes to core stability and postural control during movement and exercise.

Inspiratory Muscle Training (IMT)

IMT is a training method that involves breathing against a resistive load to strengthen the inspiratory muscles, mainly the diaphragm and accessory muscles. It is used to improve respiratory strength, endurance, and ventilatory efficiency, especially in athletes and clinical populations.

Respiratory function

Respiratory function refers to the ability of the respiratory system to ventilate, exchange gases, and maintain adequate oxygen and carbon dioxide levels. It is commonly assessed using spirometric and pressure-based measures.

Diaphragmatic dysfunction

This refers to a reduced ability of the diaphragm to generate force or excursion, leading to impaired ventilation. It may result in increased breathing effort, reduced exercise tolerance, and earlier onset of respiratory fatigue.

Maximal Inspiratory Pressure (MIP)

MIP is the maximum negative pressure generated during a forceful inspiration against an occluded airway. It is a key indicator of inspiratory muscle strength, especially diaphragmatic function.

Forced Expiratory Volume in 1 second (FEV₁)

FEV₁ is the volume of air that can be forcefully exhaled in the first second of a forced expiration. It is a standard measure of airway function and pulmonary performance.

Maximal Expiratory Pressure (MEP)

MEP represents the maximum pressure generated during a forceful expiration. It reflects the strength of expiratory muscles such as abdominal and intercostal muscles.

Forced Vital Capacity (FVC)

FVC is the total volume of air exhaled forcefully after a maximal inspiration. It reflects lung capacity and ventilatory function.

Heart rate

Heart rate is the number of heartbeats per minute. It reflects cardiovascular response to exercise intensity and autonomic nervous system activity.

Heart Rate Variability (HRV)

HRV is the variation in time intervals between consecutive heartbeats. It is a marker of autonomic nervous system balance, particularly sympathetic and parasympathetic activity.

Blood lactate

Blood lactate is a metabolic byproduct of anaerobic glycolysis. Elevated levels indicate increased reliance on anaerobic energy systems and higher metabolic stress during intense exercise.

100-meter swimming test

A standardized performance test measuring the time required to complete 100 meters freestyle swimming at maximal effort. It is used to assess anaerobic and aerobic performance capacity in swimmers.

Randomized controlled trial (RCT)

An experimental study design in which participants are randomly assigned to different intervention groups to reduce bias and ensure comparability.

Parallel design

A study design where two or more groups are followed simultaneously, each receiving a different intervention throughout the study period.

Double-blind design

A methodological approach in which neither participants nor researchers know group allocation, minimizing expectation and measurement bias.

Sham device (placebo IMT)

A device designed to mimic IMT without providing meaningful resistance, used to control for placebo effects in training studies.

Ultrasound assessment

A non-invasive imaging technique used to evaluate diaphragm structure and function in real time, including thickness and movement during breathing.

Diaphragmatic thickness

The measurement of the muscle layer of the diaphragm, often assessed at rest and during contraction to evaluate contractile capacity.

Diaphragmatic excursion

The movement amplitude of the diaphragm during breathing, reflecting its functional mobility and efficiency.