Cardiac autonomic response following high‐intensity running work‐to‐rest interval manipulation

Abstract

The cardiorespiratory, cardiac autonomic (via heart rate variability (HRV)) and plasma volume responses to varying sequences of high-intensity interval training (HIT) of consistent external work were investigated. Twelve moderately trained males underwent three HIT bouts and one control session. The HIT trials consisted of warm-up, followed by 12 min of 15 s, 30 s or 60 s work:relief HIT sequences at an exercise intensity of 100% of the individual velocity at [Formula: see text]O2max (v[Formula: see text]O2max), interspersed by relief intervals at 60% [Formula: see text]O2max (work/relief ratio = 1). HRV was evaluated via the square root of the mean sum of the squared differences between R-R intervals (rMSSD) before, 1 h, 3 h and 24 h after the exercise. Plasma volume was assessed before, immediately after, and 3 h and 24 h after. There were no substantial between-trial differences in acute cardiorespiratory responses. The rMSSD values remained decreased 1 h after the exercise cessation in all exercise groups. The rMSSD subsequently increased between 1 h and 3 h after exercise, with the most pronounced change in the 15/15 group. There were no relationships between HRV and plasma volume. All HIT protocols resulted in similar cardiorespiratory responses with slightly varying post-exercise HRV responses, with the 30/30 protocol eliciting the least disruption to post-exercise HRV. These post-exercise HRV findings suggest that the 30/30 sequence may be the preferable HIT prescription when the between-training period is limited.

IL-6, Antioxidant Capacity and Muscle Damage Markers Following High-Intensity Interval Training Protocols

“…However, the 30/30 protocol elicited the least IL-6 and Mb response while the inter-trial differences in all other analysed variables were negligible. These findings support the previously published results demonstrating the least disruption of the cardiac autonomic regulation caused by the 30/30 protocol when compared to 15/15 and 60/60 protocols (Cipryan et al, 2016). …”

“…Since the beneficial effect of IL-6 on the muscle metabolism had been shown (Raschke and Eckel, 2013), our results indicated that the 15/15 and 60/60 protocols might be preferred to the 30/30 protocols in order to maximize the training stimulus. These findings are in conformity with the sister paper, which showed a similar acute cardiorespiratory response to all three HIIT protocols as well as the least disturbance of cardiac autonomic regulation following the 30/30 HIIT protocol (Cipryan et al, 2016). …”

“…The acute cardiorespiratory response to the various HIIT protocols had been shown in the separate study (Cipryan et al, 2016). Briefly, there were trivial to small differences in the mean HR (15/15: 182.5 ± 6.9 bpm; 30/30: 179.6 ± 5.6; 60/60: 180.8 ± 7.2 bpm), at most small differences in mean $MJX-TeXAtom-ORD\dot{V}{\text{O}}_{\text{2}}$ (15/15: 50.2 ± 4.2 ml⋅kg -1 min -1 ; 30/30: 49.8 ± 3.7 ml⋅kg -1 ⋅min -1 ; 60/60: 49.5 ± 3.6 ml⋅kg -1 ⋅min -1 ) and unclear (30/30 vs. 60/60) or moderate differences in RER (15/15: 0.92 ± 0.03; 30/30: 0.94 ± 0.02; 60/60: 0.94 ± 0.03).…”

“…The acute cardiorespiratory and postexercise cardiac autonomic response to these three different single-bout HIIT sessions has been previously shown (Cipryan et al, 2016). The aim of this study was to extend these results by analysing other aspects of the exercise-induced response such as inflammation, oxidative stress and muscle damage.…”

“…The speed consequently increased to 12 km⋅h -1 , following the exercise intensity increasing by 1 km⋅h -1 every minute up to voluntary exhaustion. A detailed description was provided previously in Cipryan et al (2016).…”