Thesis Format
Integrated Article
Degree
Doctor of Philosophy
Program
Kinesiology
Supervisor
Belfry, Glen R.
Abstract
The overall aim of this dissertation was to determine the effects of breath-holding during high-intensity exercise. The response to breath-holding is known as the diving response and includes bradycardia and peripheral vasoconstriction, whereas the response to exercise includes tachycardia and peripheral vasodilation. When breath-holding occurs during low-intensity exercise, the diving response prevails, but which prevails during high-intensity exercise is unknown. Study One examined recreationally active adults performing simultaneous arm and leg ergometry at high intensity for twenty seconds with and without breath-holding. The exercise response prevailed considering heart rate was increased during breath-holding compared to free-breathing and this may have ensured sufficient oxygen delivery as there was not an increase in oxygen extraction at the muscle, or anaerobic glycolysis as determined by near infrared spectroscopy and blood lactate concentrations, respectively. Study Two examined the effects of breath-holding during high-intensity exercise in competitive swimmers habituated to breath-holding, as habituation enhances the diving response. Using the same methodology, it was found that despite signs of an enhanced diving response (increased systolic and diastolic blood pressures, indicating peripheral vasoconstriction), the exercise response prevailed. Increased heart rate may have ensured sufficient oxygen delivery considering there was not an increase in oxygen extraction at the muscle, or anaerobic glycolysis. Study 3 examined the effects of breath-holding during high-intensity swimming, as immersion of the face in water enhances the diving response. There was no difference in heart rate between breath-holding and regulated breathing, and the additive effects of facial immersion and apnea may have overridden the exercise tachycardia that was observed in the land-based studies. There was increased oxygen extraction, suggestive of vasoconstriction, at the triceps brachii muscle, due to breath-holding. Although the diving response was evident during high-intensity swimming, it did not appear to impair performance, possibly due to the short duration of exercise. Overall, it appears that the exercise response prevails over the diving response during short-duration, high-intensity exercise. These findings suggest that if there are biomechanical benefits due to not having to turn the head to breathe, breath-holding during sprint swimming should be considered a viable strategy to improve performance.
Summary for Lay Audience
In response to exercise, the heart rate increases and blood vessels widen to increase oxygen availability at exercising muscles. In response to breath-holding, the heart rate decreases and blood vessels narrow, to conserve oxygen for vital organs. This latter response is stronger under water, and in people who are used to breath-holding. This raises the question as to which of these contradictory responses prevails when exercise and breath-holding are performed simultaneously, such as during swimming. If the breath-holding response prevails, this may reduce oxygen availability for exercise and this may restrict the ability to sustain the exercise. Although the breath-holding response prevails during low-intensity exercise, the exercise can be sustained by using oxygen that was in the body prior to breath-holding and energy producing mechanisms that do not require oxygen. However, it is less clear as to what happens during high-intensity exercise considering its increased energy demands. We investigated the effects of breath-holding during twenty seconds of high-intensity exercise on adults naive to breath-holding and competitive swimmers who regularly perform breath-holds during their sport. On land, there were enough oxygen stores in the body to sustain the exercise. The exercise response dominated due to the high intensity and the duration was too short for full expression of the breath-holding response. Latent effects of the breath-holding response were observed in non-swimmers, as heart rate was lower during recovery. This was not apparent in swimmers, possibly due to training adaptations leading to quicker recovery from exercise while breath-holding. There were signs of an enhanced breath-holding response in competitive swimmers, but this was not sufficient to overcome the exercise response. In water, there was no difference in heart rate during exercise whether breath-holding or breathing regularly and there was increased use of oxygen at the triceps muscle in the arm but not at muscles in the back or leg. The breath-holding response appeared stronger in water than on land, but it did not impair performance. Collectively, these findings suggest that during short-duration, high-intensity exercise while breath-holding, there are sufficient oxygen stores in the body to sustain the exercise and performance is not impaired.
Recommended Citation
Walsh, Jeremy, "The physiological responses to breath-holding during high-intensity land-based exercise and swimming." (2025). Electronic Thesis and Dissertation Repository. 10757.
https://ir.lib.uwo.ca/etd/10757