Key result
Four weeks of sprint interval training increased the submaximal cardiac output to oxygen consumption relationship from 3.8 to 4.7 (P=0.02) in young healthy males with a low initial cardiac response.
Why the study?
Cardiovascular adaptations to exercise remain poorly understood at the individual level, so researchers evaluated the effects of sprint interval training on modulating cardiac output-oxygen consumption relationships based on individual baseline profiles.
Does 4 weeks of sprint interval training improve the submaximal cardiac output to oxygen consumption relationship in healthy young males?
Does 4 weeks of sprint interval training improve the submaximal cardiac output to oxygen consumption relationship in healthy young males?
Answers are grounded in this paper and cite their sources.
Sprint interval training improves submaximal cardiac output via increased stroke volume specifically in individuals with a low initial cardiac output-to-oxygen consumption relationship.
Cardiovascular adaptations to exercise, particularly at the individual level, remain poorly understood. Previous group level research suggests the relationship between cardiac output and oxygen consumption ([Formula: see text]-[Formula: see text]) is unaffected by training as submaximal [Formula: see text] is unchanged. We recently identified substantial inter-individual variation in the exercise [Formula: see text]-[Formula: see text] relationship that was correlated to stroke volume (SV) as opposed to arterial oxygen content. Therefore we explored the effects of sprint interval training (SIT) on modulating [Formula: see text]-[Formula: see text] given an individual's specific [Formula: see text]-[Formula: see text] relationship. 22 (21±2 yrs) healthy, recreationally active males participated in a 4-week SIT (8, 20 second sprints; 4x/week, 170% of the work rate at [Formula: see text] peak) study with progressive exercise tests (PET) until exhaustion. Cardiac output ([Formula: see text] L/min; inert gas rebreathe, Finometer Modelflow™), oxygen consumption ([Formula: see text] L/min; breath-by-breath pulmonary gas exchange), quadriceps oxygenation (near infrared spectroscopy) and exercise tolerance (6-20; Borg Scale RPE) were measured throughout PET both before and after training. Data are mean Δ from bsl±SD. Higher [Formula: see text] ([Formula: see text]) and lower [Formula: see text] ([Formula: see text]) responders were identified post hoc (n = 8/group). SIT increased the [Formula: see text]-[Formula: see text] post-training in [Formula: see text] (3.8±0.2 vs. 4.7±0.2; P = 0.02) while [Formula: see text] was unaffected (5.8±0.1 vs. 5.3±0.6; P = 0.5). [Formula: see text] was elevated beyond 80 watts in [Formula: see text] due to a greater increase in SV (all P<0.04). Peak [Formula: see text] (ml/kg/min) was increased in [Formula: see text] (39.7±6.7 vs. 44.5±7.3; P = 0.015) and [Formula: see text] (47.2±4.4 vs. 52.4±6.0; P = 0.009) following SIT, with [Formula: see text] having a greater peak [Formula: see text] both pre (P = 0.02) and post (P = 0.03) training. Quadriceps muscle oxygenation and RPE were not different between groups (all P>0.1). In contrast to [Formula: see text], [Formula: see text] responders are capable of improving submaximal [Formula: see text]-[Formula: see text] in response to SIT via increased SV. However, the increased submaximal exercise [Formula: see text] does not benefit exercising muscle oxygenation.
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Bentley et al. (2019) studied Healthy, recreationally active males (n=22). Sprint interval training (SIT) vs. Pre-training baseline was evaluated on Submaximal exercise cardiac output to oxygen consumption relationship (Q-VO2) in lower cardiac responders (p=0.02). Four weeks of sprint interval training increased the submaximal cardiac output to oxygen consumption relationship from 3.8 to 4.7 (P=0.02) in young healthy males with a low initial cardiac response.
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