Increase interval training intensity improves plasma volume variations and aerobic performances in response to intermittent exercise

Abstract Purpose We studied the effect of two interval training programs of varying intensities (100% vs. 110% of maximal aerobic velocity [MAV]) on hematocrit (Ht), hemoglobin (Hb), and plasma volume variations (PVV) in young men. Methods Thirty-nine male volunteered were assigned to two control groups (CG 100 , n = 9 and CG 110 , n = 10), and two training groups (one with 100% MAV [EG 100 , n = 10] and one with 110% MAV [EG 110 , n = 10]). All participants performed a maximal graded exercise test and an intermittent exercise (IE) protocol. Blood was collected at rest, at the end of the IE and after 15 min of recovery, before and after 8-weeks-training. Interval training (IT) sessions consist of 30s IE run at 100% or 110% MAV with 30s recovery at 50% MAV. Results After training, time to exhaustion (TTE) was improved in EG 110 (+613.7) and EG 100 (+397.5). This improvement was greater in EG 110 than EG 100 (p  100 and EG 110 at rest (p  100 (−0.6%) than EG 110 (−0.3%). After training, Ht decreased in EG 100 and EG 110 at rest (p = 0.001), at the end of IE (p = 0.000) and at 15 min of recovery (p = 0.01). This decrease was more important in EG 110 than EG 100 at rest (−2.7%), at the end of IE (−2.1%) and after 15 min recovery. After training, PVV rest and PVV end increased in EG 100 (+2.2%) and EG 110 (+3.2%). No significant difference between EG 100 and EG 110 was observed. Conclusion Increasing IT intensity by 10% MAV increases PVV rest and PVV end . Despite the fact that EG 100 and EG 110 had the same PVV end after training, greater performances were recorded in EG 110 .