Shorter intervals at peak SV vs.V̇O_2max may yield high SV with less physiological stress

The purpose of this study was to evaluate whether greater and sustainable stroke volume (SV) responses may be obtained by exercise intensities corresponding to peak SV (SV_peak) vs. maximal O₂ consumption (), and short vs. long intervals (SI vs. LI). Nine moderate- to well-trained male athletes competing at regional level specialists of cyclist, track and field volunteered to take part in the study (: 59.7 ± 7.4 mL·min⁻¹·kg⁻¹). Following familiarisation sessions, was determined, and then SV_peak was evaluated using exercise intensities at 40%–100% of by nitrous-oxide rebreathing (N₂O_RB) method. Then each separate participant exercised wattages corresponding to individual and SV_peak during both SI (SI and SI_SVpeak) and LI (LI and LI_SVpeak) workouts on a cycle ergometer. Main results showed that both SI and SI_SVpeak yielded greater SV responses than LI and LI_SVpeak (p ≤ 0.05). Mean SV responses were greater in LI_SVpeak than in LI (p ≤ 0.05), but there was no statistical difference between SI_SVpeak and SI. However, there was significantly less physiological stress based on VO₂, respiratory exchange ratio, heart rate and rate of perceived exhaustion in SV_peak than in intensities (p ≤ 0.05). Moreover, SV responses at exercise phases increased in the early stages and remain stable until the end of SI and SI_SVpeak workouts (p > 0.05), while they were gradually decreasing in LI and LI_SVpeak sessions (p ≤ 0.05). In conclusion, if the aim of a training session is to improve SV_peak with less physiological stress, SI_SVpeak seems a better alternative than other modalities tested in the present study.