High-intensity interval training improves respiratory and cardiovascular adjustments before and after initiation of exercise

Go Ito; Marina Feeley; Toru Sawai; Hideomi Nakata; Shingo Otsuki; Hidehiro Nakahara; Tadayoshi Miyamoto

doi:10.3389/fphys.2024.1227316

High-intensity interval training improves respiratory and cardiovascular adjustments before and after initiation of exercise

Front Physiol. 2024 Mar 11:15:1227316. doi: 10.3389/fphys.2024.1227316. eCollection 2024.

Authors

Go Ito¹, Marina Feeley¹, Toru Sawai², Hideomi Nakata^{1

2}, Shingo Otsuki^{1

2}, Hidehiro Nakahara³, Tadayoshi Miyamoto^{1

2}

Affiliations

¹ Graduate School of Human Environment, Osaka Sangyo University, Daito City, Osaka, Japan.
² Department of Sport and Health Sciences, Faculty of Sport and Health Sciences, Osaka Sangyo University, Daito City, Osaka, Japan.
³ Graduate School of Health Sciences, Morinomiya University of Medical Sciences, Osaka City, Osaka, Japan.

Abstract

Purpose: High-intensity interval training (HIIT) may induce training-specific physiological adaptations such as improved respiratory and cardiovascular adjustments before and after the onset of high-intensity exercise, leading to improved exercise performance during high-intensity exercise. The present study investigated the effects of HIIT on time-dependent cardiorespiratory adjustment during maximal exercise and before and after initiation of high-intensity exercise, as well as on maximal exercise performance. Methods: 21 healthy male college students were randomly assigned to HIIT group (n = 11) or control group (n = 10). HIIT group performed training on a cycle ergometer once a week for 8 weeks. The training consisted of three bouts of exercise at 95% maximal work rate (WR_max) until exhaustion. Before and after the HIIT program, dynamic cardiorespiratory function was investigated by ramp and step exercise tests, and HIIT-induced cardiac morphological changes were assessed using echocardiography. Results: HIIT significantly improved not only maximal oxygen uptake and minute ventilation, but also maximal heart rate (HR), systolic blood pressure (SBP), and time to exhaustion in both exercise tests (p < 0.05). Time-dependent increases in minute ventilation (V_E) and HR before and at the start of exercise were significantly enhanced after HIIT. During high-intensity exercise, there was a strong correlation between percent change (from before to after HIIT program) in time to exhaustion and percent change in HR_max (r = 0.932, p < 0.001). Furthermore, HIIT-induced cardiac morphological changes such as ventricular wall hypertrophy was observed (p < 0.001). Conclusion: We have demonstrated that HIIT at 95% WR_max induces training-specific adaptations such as improved cardiorespiratory adjustments, not only during maximal exercise but also before and after the onset of high-intensity exercise, improvement of exercise performance mainly associated with circulatory systems.

Keywords: blood pressure; constant-load exercise; heart rate; maximal exercise performance; maximal oxygen uptake; ramp-load exercise.

Grants and funding

This study was supported in part by a Grant-in-Aid for Scientific Research (grant number 18K10912, 22H03476) from the Japanese Ministry of Education, Culture, Sports, Science and Technology, and by grants to TM from the Descente and Ishimoto Memorial Foundation for the Promotion of Sports Science.