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 (CG₁₀₀, n = 9 and CG₁₁₀, n = 10), and two training groups (one with 100% MAV [EG₁₀₀, n = 10] and one with 110% MAV [EG₁₁₀, 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 EG₁₁₀ (+613.7) and EG₁₀₀ (+397.5). This improvement was greater in EG₁₁₀ than EG₁₀₀ (p < 0.005). After training, Hb deceased in EG₁₀₀ and EG₁₁₀ at rest (p < 0.01), at the end of IE (p = 0.000) and after 15 min of recovery (p = 0.01). This decrease was more slightly more substantial at rest in EG₁₀₀ (-0.6%) than EG₁₁₀ (-0.3%). After training, Ht decreased in EG₁₀₀ and EG₁₁₀ 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 EG₁₁₀ than EG₁₀₀ 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 EG₁₀₀ (+2.2%) and EG₁₁₀ (+3.2%). No significant difference between EG₁₀₀ and EG₁₁₀ was observed.

Conclusion: Increasing IT intensity by 10% MAV increases PVV_rest and PVV_end. Despite the fact that EG₁₀₀ and EG₁₁₀ had the same PVV_end after training, greater performances were recorded in EG₁₁₀.

Keywords: Blood viscosity; Endurance performance; Exercise intensity; Intermittent training.