ACUTE EFFECTS OF INSPIRATORY MUSCLE WARM-UP ON INSPIRATORY MUSCLE STRENGTH DURING AEROBIC AND ANAEROBIC EXERCISE IN ATHLETES

Inspiratory muscle warm-up (IMW) has emerged as a non-pharmacological pre-exercise strategy aimed at enhancing respiratory muscle readiness prior to physical activity. The inspiratory muscles, particularly the diaphragm and accessory respiratory muscles, play a critical role in meeting increased ventilatory demands during exercise. Acute respiratory muscle fatigue has been associated with reduced performance through mechanisms such as altered ventilatory efficiency and activation of the respiratory muscle metaboreflex, which may redistribute blood flow away from locomotor muscles. While previous studies have reported beneficial acute effects of IMW on respiratory and performance parameters, the temporal characteristics of these effects during ongoing exercise remain insufficiently understood.

Existing research has primarily focused on pre- and post-intervention comparisons, often evaluating inspiratory muscle strength immediately following IMW without assessing how long these acute improvements persist during exercise. Furthermore, the influence of exercise intensity domains and athlete specialization (aerobic vs. anaerobic disciplines) on the duration of IMW-induced effects has not been systematically investigated. Another limitation of prior studies is the limited use of placebo-controlled designs, which are important for distinguishing physiological effects from expectancy or psychological influences associated with warm-up interventions.

The present study is designed as a repeated-measures interventional investigation to evaluate the acute time course of inspiratory muscle strength responses following inspiratory muscle warm-up under different exercise conditions. Each participant will complete three experimental sessions, including: (1) an active inspiratory muscle warm-up protocol performed at a standardized relative intensity, (2) a placebo breathing warm-up designed to mimic the intervention without providing a meaningful physiological load, and (3) a control condition without respiratory warm-up. The order of conditions will be counterbalanced to minimize order effects.

Exercise trials will involve treadmill running performed at predefined intensity domains representing aerobic and anaerobic workloads based on individual maximal heart rate. Inspiratory muscle strength will be measured repeatedly throughout exercise to identify the time-dependent decline relative to baseline and post-warm-up levels. This design allows examination of both immediate and sustained effects of respiratory muscle preparation strategies.

By comparing responses between athletes from predominantly aerobic and anaerobic sports backgrounds, the study seeks to explore whether differences in energy system utilization, muscle fiber composition, and ventilatory demands influence the effectiveness and duration of inspiratory muscle warm-up. The findings may contribute to a more precise understanding of respiratory muscle preparation and support evidence-based integration of breathing-specific warm-up strategies into athletic training and competition routines.

Inclusion criteria

• Age between 14 and 30 years.
• Regular participation in organized sports training for at least 4 years.
• Engaged in predominantly aerobic or anaerobic sports disciplines.
• Training frequency of at least 3 sessions per week.
• No known cardiopulmonary disease affecting respiratory function.
• Ability to safely perform maximal effort treadmill exercise.
• No respiratory illness within the last 12 weeks.
• Willingness to comply with study procedures.
• Provision of written informed consent (and parental consent for minors where applicable).

Exclusion criteria

• History of asthma, chronic obstructive pulmonary disease (COPD), or other respiratory disorders.
• Age below 14 years or above 30 years.
• Orthopedic injury or condition limiting running ability.
• Participation in inspiratory muscle training within the last 12 months.
• Use of medications affecting respiratory or cardiovascular function.
• Active smoking.
• Failure to provide informed consent.