| Autor: |
Nascimento EMF; Physical Effort Laboratory, Sports Center, Federal University of Santa Catarina, SC, Florianópolis, Brazil., Borszcz FK; Physical Effort Laboratory, Sports Center, Federal University of Santa Catarina, SC, Florianópolis, Brazil.; Human Performance Research Group, Center for Health and Sport Sciences, University of Santa Catarina State, Florianópolis, SC, Brazil., Ventura TP; Physical Effort Laboratory, Sports Center, Federal University of Santa Catarina, SC, Florianópolis, Brazil., Boaventura BCB; Department of Nutrition, Health Sciences Center, Federal University of Santa Catarina, Campus Trindade, Florianópolis, SC, Brazil., do Nascimento Salvador PC; Physical Effort Laboratory, Sports Center, Federal University of Santa Catarina, SC, Florianópolis, Brazil.; Leonardo da Vinci University-Uniasselvi/VITRU Education, Indaial, SC, Brazil., Guglielmo LGA; Physical Effort Laboratory, Sports Center, Federal University of Santa Catarina, SC, Florianópolis, Brazil., Dantas de Lucas R; Physical Effort Laboratory, Sports Center, Federal University of Santa Catarina, SC, Florianópolis, Brazil. |
| Abstrakt: |
This study aimed to investigate the effects of caffeine ingestion by chewing gum (GUMCAF) combined with priming exercise on pulmonary oxygen uptake (V˙O2) and near-infrared spectroscopy-derived muscle oxygen extraction (HHb + Mb) kinetics during cycling performed in a severe-intensity domain. Fifteen trained cyclists completed four visits: two under a placebo gum (GUMPLA) and two under GUMCAF ingestion. Each visit consisted of two square-wave cycling bouts at Δ70 intensity (70% of difference between the V˙O2 at first ventilatory threshold and V˙O2max) with duration of 6 min each and 5 min of passive rest between the bouts. The GUMPLA or GUMCAF (400 mg) was chewed for 5 min, 12 min before the first Δ70 bout in a randomized double-blind procedure. The fundamental phase and slow component of HHb + Mb and V˙O2 kinetics were evaluated. For HHb + Mb kinetics, regardless of ingested gum, priming exercise effects occurred on the time constant (GUMCAF 16.0 ± 4.0 vs. 13.9 ± 2.9 s; GUMPLA 15.7 ± 6.1 vs. 13.2 ± 2.5 s), amplitude, slow component, time delay, and mean response time parameters (p ≤ .032). For V˙O2 kinetics, there were significant effects of bouts on the amplitude, slow component, end V˙O2, and the gain kinetics parameters (p < .017). Baseline V˙O2 was higher during GUMCAF than GUMPLA (p = .020). No significant effects occurred for the interaction between gum and bout in any parameter of V˙O2 or HHb + Mb kinetics. Therefore, unlike the priming exercise in severe-intensity exercise, GUMCAF is not an effective strategy for improving V˙O2 or HHb + Mb kinetics acceleration. |
