Oleksandr Romanchuk, Yaroslav Svyshch, Oksana Guzii
Significant within-group change was confined to the strength-endurance group: lower heart rate (- 9.8%), longer RR (+ 10.8%) and QT (+ 4.8%), a higher systolic-pressure LF/HF ratio (+ 91%) and respiratory changes including minute ventilation and VO₂ (both - 23.8%; all q ≤ 0.043). The general-endurance group changed significantly only in QT and the Skibinski index. Groups did not differ in absolute values; however, the group × time interaction was significant only in the ventilatory domain and persisted after normalization to body mass (p = 0.008), whereas chronotropic, spectral-HRV and haemodynamic changes did not. Controlled-breathing reactivity declined in both groups; fitness improved across a military-applied battery, most in strength endurance.
INTRODUCTION: Physical training reshapes cardiovascular and autonomic regulation, yet the resting divergence between general- and strength-endurance loading is poorly characterized in cadets.
METHODS: In this observational study, male cadets administratively assigned to predominantly general- (n = 27) or strength-endurance (n = 25) training were examined before and after a 4-month programme. Resting electrocardiography, heart-rate, blood-pressure and respiratory variability, breathing pattern and baroreflex sensitivity were recorded by spiroarteriocardiorhythmography during spontaneous and paced (0.1, 0.25 Hz) breathing. Within-group change was tested with Wilcoxon signed-rank tests and the group × time interaction with Mann-Whitney tests on change scores, under Benjamini-Hochberg false-discovery-rate control.
RESULTS: Significant within-group change was confined to the strength-endurance group: lower heart rate (- 9.8%), longer RR (+ 10.8%) and QT (+ 4.8%), a higher systolic-pressure LF/HF ratio (+ 91%) and respiratory changes including minute ventilation and VO₂ (both - 23.8%; all q ≤ 0.043). The general-endurance group changed significantly only in QT and the Skibinski index. Groups did not differ in absolute values; however, the group × time interaction was significant only in the ventilatory domain and persisted after normalization to body mass (p = 0.008), whereas chronotropic, spectral-HRV and haemodynamic changes did not. Controlled-breathing reactivity declined in both groups; fitness improved across a military-applied battery, most in strength endurance.
DISCUSSION: These exploratory findings suggest that the divergence between loadings is one of within-programme trajectory rather than absolute level, the only robust between-group signal being ventilatory economization. Spectral HRV did not change significantly, and the autonomic and cardiac findings should be regarded as hypothesis-generating.