Prolonged exercise shifts ventilatory parameters at the moderate-to-heavy intensity transition

• Published in: European journal of applied physiology 2024-01, Vol.124 (1), p.309-315
• Main Authors: Stevenson, Julian D., Kilding, Andrew E., Plews, Daniel J., Maunder, Ed
• Format: Article
• Language: English
• Subjects: Athletes; Bicycling; Biomedical and Life Sciences; Biomedicine; Carbon dioxide; Endurance Training; Exercise; Exercise intensity; Exercise Test; Female; Heart rate; Human Physiology; Humans; Lung; Occupational Medicine/Industrial Medicine; Original; Original Article; Oxygen Consumption; Physiology; Respiration; Sports Medicine; Tidal Volume; Triathlon; Ventilation
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-023-05285-2

Purpose To quantify the effects of prolonged cycling on the rate of ventilation ( V ˙ E ), frequency of respiration (F R ), and tidal volume (V T ) associated with the moderate-to-heavy intensity transition. Methods Fourteen endurance-trained cyclists and triathletes (one female) completed an assessment of the moderate-to-heavy intensity transition, determined as the first ventilatory threshold (VT 1 ), before (PRE) and after (POST) two hours of moderate-intensity cycling. The power output, V ˙ E , F R , and V T associated with VT 1 were determined PRE and POST. Results As previously reported, power output at VT 1 significantly decreased by ~ 10% from PRE to POST. The V ˙ E associated with VT 1 was unchanged from PRE to POST (72 ± 12 vs. 69 ± 13 L . min −1 , ∆ − 3 ± 5 L . min −1 , ∆ − 4 ± 8%, P  = 0.075), and relatively consistent (within-subject coefficient of variation, 5.4% [3.7, 8.0%]). The V ˙ E associated with VT 1 was produced with increased F R (27.6 ± 5.8 vs. 31.9 ± 6.5 breaths . min −1 , ∆ 4.3 ± 3.1 breaths . min −1 , ∆ 16 ± 11%, P  = 0.0002) and decreased V T (2.62 ± 0.43 vs. 2.19 ± 0.36 L . breath −1 , ∆ − 0.44 ± 0.22 L . breath −1 , ∆ − 16 ± 7%, P  = 0.0002) in POST. Conclusion These data suggest prolonged exercise shifts ventilatory parameters at the moderate-to-heavy intensity transition, but V ˙ E remains stable. Real-time monitoring of V ˙ E may be a useful means of assessing proximity to the moderate-to-heavy intensity transition during prolonged exercise and is worthy of further research.