Jernej Kapus

Can high intensity workloads be simulated at moderate intensities by reduced breathing frequency

Objectives: This study was designed to investigate whether reduced breathing frequency during moderate intensity exercise produces similar metabolic responses as during exercise with spontaneous breathing at higher absolute intensity. Methods: Eight healthy male subjects performed a constant load test with reduced breathing frequency at 10 breaths per minute to exhaustion (B10) at the peak power output obtained during the incremental test with RBF (peak power output increased every two minutes for 30 W). The subjects then performed a constant load test with the spontaneous breathing to exhaustion (SB) at peak power output obtained during the incremental test with spontaneous breathing. Results: Respiratory parameters (V E, PETO2, PETCO2), metabolic parameters (V O2, V · CO2) and oxygen saturation (SaO2) were measured during both constant load tests. Capillary blood samples were taken before and every minute during both constant load tests in order to measure lactate concentration ([LA-]) and parameters of capillary blood gases and acid base status (PO2, PCO2, pH). Regardless of the type of comparison (the data obtained at the defined time or maximum and minimum values during the exercise), there were significant differences between SB and B10 in all respiratory parameters, metabolic parameters and SaO2 (p ≤ 0.01 and 0.05). There were significantly lower [LA-] and PCO2 during B10, when compared to SB (p≤0.01). However, there were no significant differences in pH during the exercise between different breathing conditions. Conclusion: It can be concluded that reduced breathing frequency during exercise at lower absolute intensity did not produce similar conditions as during the exercise with spontaneous breathing at higher absolute intensity. KEY WordS: reduced breathing frequency, respiratory acidosis, constant load exercise In some previous studies, swimmers reduced their breathing frequency during tethered front crawl swimming [3, 24, 29], during front crawl interval sets [8], during front crawl swimming at OBLA velocity [13] and during maximal front crawl swimming [14]. These studies were unable to demonstrate hypoxia conditions by analysing the air expired during the exercise [3, 8, 29] or by measuring capillary blood sampled after the exercise [13, 14]. Considering the obtained higher partial pressure of CO2, they concluded that this kind of training is more likely hypercapnic training. Due to the technical limitations of measuring respiratory and blood parameters during swimming, the idea of RBF during exercise on land has been also investigated; examples include cycle ergometry [12, 25, 32] and treadmill running [21]. These studies confirmed marked hypercapnia as result of RBF during exercise. In addition, they also obtained hypoxia by measuring capillary blood sampled and oxygen saturation (SaO2) during exercise with RBF. All of the reported studies compared the subjects’ response during exercise with different breathing conditions (spontaneous and RBF) at the same absolute intensity. However, the question is whether RBF during moderate Original Pap r Biol. Sport 2010;27:163-168

The Influence of Reduced Breathing During Incremental Bicycle Exercise on Some Ventilatory and Gas Exchange Parameters

The purpose of this study was to examine the ventilatory, gas exchange, oxygen saturation and heart rate response to reduced breathing frequency during an incremental bicycle exercise. Eight healthy male subjects performed an incremental bicycle exercise test on an electromagnetically braked cycle ergometer twice: first with continuous breathing (CB), and second with reduced breathing frequency (B10), which was defined as 10 breaths per minute. As work rates increased, significantly higher VE, Vco2 and R were measured during the exercise with SB than during the exercise with B10. Consequently, PETco2 and PETo2 were higher and lower, respectively, during the exercise with B10 than during the exercise with SB at 150 W. In addition, HR was greater during the exercise with SB than during the exercise with B10; significant differences were achieved at 90, 120 and 150W. However, Vo2 showed no significant difference between the exercises in two different breathing conditions. In summary, reduced breathing frequency during the incremental bicycle exercise decreased VE and consequently decreased So2 and increased PETco2. However, it seemed that this degree of breathing reduction did not influence on aerobic metabolism due to unchanged Vo2.

Impact of weekly swimming training distance on the ergogenicity of inspiratory muscle training in well trained youth swimmers.

Lomax, M, Kapus, J, Brown, PI, and Faghy, M. Impact of weekly swimming training distance on the ergogenicity of inspiratory muscle training in well-trained youth swimmers. J Strength Cond Res 33(8): 2185-2193, 2019-The aim of this study was to examine the impact of weekly swimming training distance on the ergogenicity of inspiratory muscle training (IMT). Thirty-three youth swimmers were recruited and separated into a LOW and HIGH group based on weekly training distance (≤31 km·wk and >41 km·wk, respectively). The LOW and HIGH groups were further subdivided into control and IMT groups for a 6-week IMT intervention giving a total of 4 groups: LOWcon, LOWIMT, HIGHcon, and HIGHIMT. Before and after the intervention period, swimmers completed maximal effort 100- and 200-m front crawl swims, with maximal inspiratory and expiratory mouth pressures (PImax and PEmax, respectively) assessed before and after each swim. Inspiratory muscle training increased PImax (but not PEmax) by 36% in LOWIMT and HIGHIMT groups (p ≤ 0.05), but 100- and 200-m swims were faster only in the LOWIMT group (3 and 7% respectively, p ≤ 0.05). Performance benefits only occurred in those training up to 31 km·wk and indicate that the ergogenicity of IMT is affected by weekly training distance. Consequently, training distances are important considerations, among others, when deciding whether or not to supplement swimming training with IMT.

Cardiorespiratory Responses of Adults and Children during Normoxic and Hypoxic Exercise

We aimed to elucidate potential differential effects of hypoxia on cardiorespiratory responses during submaximal cycling and simulated skiing exercise between adults and pre-pubertal children. Healthy, low-altitude residents (adults, N=13, Age=40±4yrs.; children, N=13, age=8±2yrs.) were tested in normoxia (Nor: PiO2=134±0.4 mmHg; 940 m) and normobaric hypoxia (Hyp: PiO2=105±0.6 mmHg; ~3 000 m) following an overnight hypoxic acclimation (≥12-hrs). On both days, the participants underwent a graded cycling test and a simulated skiing protocol. Minute ventilation (VE), oxygen uptake (VO2), heart rate (HR) and capillary-oxygen saturation (SpO2) were measured throughout both tests. The cycling data were interpolated for 2 relative workload levels (1 W·kg-1 & 2 W·kg-1). Higher resting HR in hypoxia, compared to normoxia was only noted in children (Nor:78±17; Hyp:89±17 beats·min-1; p<0.05), while SpO2 was significantly lower in hypoxia (Nor:97±1%; Hyp:91±2%; p<0.01) with no between-group differences. The VE, VO2 and HR responses were higher during hypoxic compared to normoxic cycling test in both groups (p<0.05). Except for greater HR during hypoxic compared to normoxic skiing in children (Nor:155±19; Hyp:167±13 (beats·min-1); p<0.05), no other significant between-group differences were noted during the cycling and skiing protocols. In summary, these data suggest similar cardiorespiratory responses to submaximal hypoxic cycling and simulated skiing in adults and children.