Effects of high intensity continuous and intermittent training strategies used for endurance development on cardio-vascular responses

Abstract

Purpose of the present study was to examine the potential effects of five high intensity training (HIT) models on central and peripheral components of VO 2max . We analysed O 2 consumption (VO 2 ), cardiac output (Q), stroke volume (SV), heart rate (HR) and arteriovenous O 2 difference (a-vO 2diff ) in different regimes of HIT during loading and recovery periods. Eight well-trained male competitive cyclists take part in the study (age: 22.1±3.1 years; body mass: 66.2±8.5 kg; height: 175.4±5.2 cm; body fat: 7.2%±1.1%; O 2max : 64±5.61 mL∙min -1 ∙kg -1 ). Following familiarization sessions, VO 2max was determined, and then, maximal SV, HR, Q and a-vO 2diff (SV max ), (HR max ), (Q max ), (a-vO 2diff_max ) were evaluated individually using exercise intensities corresponding to 40 to 110% of VO 2max separately, by nitrous-oxide re-breathing (N 2 O RB ) method. Thereafter, training models were performed as; HIT 1 : 16 repetitions with power at ~110% of VO 2max for 45-sec (16A—45-sec, p@~110%VO 2max ) with 1:1 work and recovery (w/r) ratio; HIT 2 : 4A—3-min at p@~93%VO 2max with 1:1 w/r ratio; HIT 3 : alternating the power between VO 2max (1-min) and anaerobic threshold (4-min) A— 5 repetitions; HIT 4 : 25-min constant-load, HIT 5 : 6A—30-sec at 7,5% body weight with 1:7 w/r ratio. All participants reached exhaustion at all tested HIT models. After the repeated-measures analyses, possible significant differences were investigated by post-hoc LSD/Wilcoxon. T spent above 95% of VO 2max was higher in HIT 2 session than other exercise modalities (p 0.05); T spent at VO 2max was lowest in HIT 5 (p<0.05). T spent at Q max was higher in HIT 2 and HIT 3 sessions than HIT 1 , HIT 2 and HIT 5 (p<0.05). T spent at SV max was higher in HIT 3 and HIT 4 modalities than HIT 1 and HIT 2 . T spent at 95% of HR max was higher in HIT 2 session than other exercise modalities (p<0.05). T spent at a-vO 2diff_max was higher in HIT 1 and HIT 2 than HIT 3 , HIT 4 and HIT 5 (p<0.05). These results show that different exercise modalities reaching similar VO 2max levels may be effective in the development of central or peripheral components associated with VO 2max . It may be said that continuous HIT modalities seems to have a higher potential to improve central part of VO 2max , while intermittent HIT modalities seems better for peripheral one.