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Acute bouts of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) transiently lower systolic blood pressure (SBP) and diastolic blood pressure (DBP) in the hours after termed postexercise hypotension (PEH); however, the effects of sprint interval training (SIT) exercise have yet to be explored in middle-age adults. Although previous work has found no effect of exercise intensity on PEH, no study has compared submaximal, near maximal, and supramaximal intensities, specifically in middle-age adults where blood pressure (BP) management strategies may be of greater importance.This study examined the effects of MICT, HIIT, and SIT exercises on PEH in the immediate (≤2 h) and 24 h after exercise specifically in middle-age adults.Fourteen participants (10 female; age, 46 ± 9 yr; SBP, 116 ± 11 mm Hg; DBP, 67 ± 6 mm Hg; one hypertensive, four prehypertensive, nine normotensive) had their BP measured before, immediately (15, 30, 60, 120 min), and over 24 h after four experimental sessions: 1) 30-min MICT exercise (65% maximal oxygen consumption), 2) 20-min HIIT exercise (10 × 1 min at 90% maximum heart rate with 1-min rest), 3) 16-min SIT exercise (8 × 15 s all-out sprints with 2-min rest), and 4) no-exercise control. Postexercise BP was compared with no-exercise control.PEH was similar for all exercise sessions for SBP ( P = 0.388, = 0.075) and DBP ( P = 0.206, = 0.108). Twenty-four-hour average SBP was similar for all sessions P = 0.453, = 0.069), and DBP was similar over 24 h except after MICT exercise compared with HIIT exercise ( P = 0.018, d = 1.04).In middle-age adults, MICT, HIIT, and SIT exercises are effective at reducing SBP; however, the effects on DBP are smaller, and neither reductions are sustained over 24 h.

High-intensity interval training and sprint interval training significantly increase maximal oxygen uptake (V̇O 2max ), which enhances endurance performance and health status. Whether this response is due to increases in central cardiovascular function (cardiac output (CO) and blood volume) or peripheral factors is unknown.This study aimed to conduct a systematic review and meta-analysis to assess the effects of high-intensity interval training and sprint interval training (referred to as intense interval training) on changes in central cardiovascular function.We performed a systematic search of eight databases for studies denoting increases in V̇O 2max in which CO, stroke volume (SV), blood volume, plasma volume, end-diastolic/systolic volume, or hematocrit were measured.Forty-five studies were included in this analysis, comprising 946 men and women of various health status (age and V̇O 2max , 20-76 yr and 13-61 mL·kg -1 ·min -1 ) who performed 6-96 sessions of interval training. Results showed an increase in V̇O 2max with intense interval training that was classified as a large effect ( d = 0.83). SV ( d = 0.69), and CO ( d = 0.49) had moderate effect sizes in response to intense interval training. Of 27 studies in which CO was measured, 77% exhibited significant increases in resting CO or that obtained during exercise. Similarly, 93% of studies revealed significant increases in SV in response to intense interval training. Effect sizes for these outcomes were larger for clinical versus healthy populations. Plasma volume, blood volume, and hematocrit had small effect sizes after training ( d = 0.06-0.14).Increases in V̇O 2max demonstrated with intense interval training are attendant with increases in central O 2 delivery with little contribution from changes in hematocrit, blood volume, or plasma volume.

Brain-derived neurotrophic factor (BDNF) is an exercise-induced neurotropin mediating neuroprotection and synaptic plasticity. Although exercise intensity is implicated as a potentially important mediator of BNDF release after exercise, the optimal exercise stimulus (interval vs continuous) and intensity (submaximal vs supramaximal) for augmenting circulating BDNF levels remains unknown. Irisin, an exercise-driven myokine, may also contribute to neuroprotection by upregulating BDNF.To examine the response and recovery of plasma BDNF and irisin after acute exercise of differing intensities.Eight males (23.1 ± 3.0 yr of age; V˙O2max 51.2 ± 4.4 mL·kg·min) completed four acute exercise sessions: 1) moderate-intensity continuous training (MICT, 65% V˙O2max); 2) vigorous-intensity continuous training (VICT, 85% V˙O2max); 3) sprint interval training (SIT, "all out"); and 4) no exercise (CTRL). Blood was collected preexercise as well as immediately, 30 min, and 90 min postexercise. Plasma BDNF and irisin were assessed with commercially available enzyme-linked immunosorbent assay kits.Plasma BDNF levels increased immediately after exercise in the SIT group (P0.0001) with plasma concentrations recovering 30 and 90 min postexercise. The BDNF levels after MICT were reduced 30 min postexercise compared with immediately postexercise (P = 0.0189), with no other changes across time points in MICT and VICT groups. Plasma BDNF area under the curve in SIT was significantly higher compared with CTRL, MICT, and VICT (P = 0.0020). No changes in plasma irisin across exercise groups and time points were found (P0.9999).Plasma BDNF levels increased in an intensity-dependent manner with SIT eliciting the highest BDNF concentration immediately postexercise. These results identify SIT as a time-efficient exercise modality to promote brain health through BDNF release.