Inspiratory Loading Intensity Does Not Influence Lactate Clearance during Recovery

Influence of voluntary isocapnic hyperpnoea on recovery after high-intensity exercise in elite short-track speedskaters - randomized controlled trial

Respiratory muscle training plays a significant role in reducing blood lactate concentration (bLa) and attenuating negative physiological stress reactions. Therefore, we investigated if voluntary isocapnic hyperpnoea (VIH) performed after a maximum anaerobic effort influences bLa and perceived fatigue level in well-trained speedskaters. 39 elite short-track speedskaters participated in a trial with two parallel groups: experimental and control. All the participants performed the Wingate Anaerobic Test (WAnT). The experimental group performed a VIH-based recovery protocol 20 min after exercise, the control group used passive recovery only. Blood samples were taken 3 and 30 min after the WAnT to measure bLa. Fatigue was self-appraised on a 0-10 perceived rating-of-fatigue (ROF) scale 3 and 30 min after the WAnT. Noteworthy, but not statistically significant changes between the experimental and control groups were observed for changes in bLa (p = 0.101). However, statistically significant changes between the groups were found for ROF (p = 0.003, ηp2 = 0.211, ω2 = 0.106). Moreover, statistically significant interactions between post-exercise bLa clearance and VO2max (p = 0.028) and inspiratory muscle strength (p = 0.040) were observed. Our findings provided preliminary insight that VIH may be an efficient recovery protocol after anaerobic exercise performed by elite athletes. The association between VO2max and post-exercise bLa clearance indicates the vital role of aerobic fitness in repeated-efforts ability in short-track speedskaters. The study was registered at ClinicalTrials.gov as NCT05994092 on 15th August 2023.

Acute effect of inspiratory resistive loading on sprint interval exercise performance in team-sport athletes

This study examined acute effects of inspiratory resistive loading (IRL) during rest intervals on sprint interval exercise (SIE) performance. In a randomized crossover design, nine collegiate basketball players performed IRL (15 cmH₂O) or passive recovery (CON) at 5-min rest intervals during and immediately after 6 sets of a 30-s SIE test. Performance, muscular oxygenation of vastus lateralis, blood lactate and pH were measured at each condition. Blood lactate at 5-min (-20.5 %) and 20-min (-21.3 %) after SIE were significantly lower in IRL than in CON. The pH at 5-min after SIE was significantly higher in IRL than in CON (+0.8 %, p <  0.05). However, the total work in IRL was significantly lower than in CON (-2.7 %, p <  0.05). Average changes in total hemoglobin at rest intervals in IRL were significantly lower than in CON (-34.5 %, p <  0.05). The IRL could attenuate exercise-induced metabolic acidosis; however, the decreased blood flow at rest intervals might increase the physical challenge in SIE.

Prior upper body exercise reduces cycling work capacity but not critical power

PURPOSE

This study examined whether metabolite accumulation, induced by prior upper body exercise, affected the power-duration relationship for leg cycle ergometry.

METHODS

Seven males performed, to the limit of tolerance and both without (L) and with (AL) prior severe-intensity arm-cranking exercise, an incremental cycling test and four constant power cycling tests to determine the parameters of the power-duration relationship: critical power (CP) and W'.

RESULTS

At the onset of cycling exercise plasma lactate (L vs AL: 1.2 ± 0.1 vs 11.6 ± 2.9 mEq · L) and hydrogen ion (40.4 ± 1.3 vs 53.1 ± 4.3 nEq · L), concentrations were higher during AL compared with L, whereas the strong ion difference (37.8 ± 1.8 vs 32.4 ± 2.0 mEq · L) and bicarbonate concentration (25.7 ± 0.7 vs 18.3 ± 1.9 mEq · L) were lower during AL compared with L (P < 0.01). During incremental exercise, maximum cycling power (358 ± 15 vs 332 ± 21 W) and peak oxygen uptake (VO2peak) (4.31 ± 0.36 vs 3.71 ± 0.44 L · min) were lower during AL compared with L (P < 0.05). The rate of increase in plasma potassium concentration during constant power cycling was greater during AL compared with L (0.09 ± 0.08 vs 0.14 ± 0.13 mEq · L · min) (P < 0.05), and exercise duration was 35 ± 15% shorter (P < 0.01). CP was not different between L and AL (267 ± 19 vs 264 ± 20 W), whereas W' was lower in AL (17.3 ± 5.7 vs 11.8 ± 4.2 kJ) (P < 0.01).

CONCLUSION

The reduced W' after prior upper body exercise indicates that the magnitude of W' is partly dependent on metabolite accumulation.

Inspiratory muscle warm-up does not improve cycling time-trial performance

PURPOSE

This study examined the effects of an active cycling warm-up, with and without the addition of an inspiratory muscle warm-up (IMW), on 10-km cycling time-trial performance.

METHODS

Ten cyclists (VO₂ = 65 ± 9 mL kg(-1) min(-1)) performed a habituation 10-km cycling time-trial and three further time-trials preceded by either no warm-up (CONT), a cycling-specific warm-up (CYC) comprising three consecutive 5-min bouts at powers corresponding to 70, 80, and 90% of the gas exchange threshold, or a cycling-specific warm-up preceded by an IMW (CYC + IMW) comprising two sets of 30 inspiratory efforts against a pressure-threshold load of 40% maximal inspiratory pressure (MIP). The cycling warm-up was followed by 2-min rest before the start of the time-trial.

RESULTS

Time-trial performance times during CYC (14.75 ± 0.79 min) and CYC + IMW (14.70 ± 0.75 min) were not different, although both were faster than CONT (14.99 ± 0.90 min) (P < 0.05). Throughout the time-trial, physiological (minute ventilation, breathing pattern, pulmonary gas exchange, heart rate, blood lactate concentration and pH) and perceptual (limb discomfort and dyspnoea) responses were not different between CYC and CYC + IMW. Baseline MIP during CONT and CYC was 151 ± 31 and 156 ± 39 cmH₂O, respectively, and was unchanged following the time-trial. MIP increased by 8% after IMW (152 ± 27 vs. 164 ± 27 cmH2O, P < 0.05) and returned to baseline after the time-trial.

CONCLUSIONS

Improvements in 10-km cycling time-trial performance following an active cycling warm-up were not magnified by the addition of an IMW. Therefore, an appropriately designed active whole-body warm-up does adequately prepare the inspiratory muscles for cycling time-trials lasting approximately 15 min.

Influence of oxidative stress, diaphragm fatigue, and inspiratory muscle training on the plasma cytokine response to maximum sustainable voluntary ventilation

The influence of oxidative stress, diaphragm fatigue, and inspiratory muscle training (IMT) on the cytokine response to maximum sustainable voluntary ventilation (MSVV) is unknown. Twelve healthy males were divided equally into an IMT or placebo (PLA) group, and before and after a 6-wk intervention they undertook, on separate days, 1 h of ( 1) passive rest and ( 2) MSVV, whereby participants undertook volitional hyperpnea at rest that mimicked the breathing and respiratory muscle recruitment patterns commensurate with heavy cycling exercise. Plasma cytokines remained unchanged during passive rest. There was a main effect of time ( P < 0.01) for plasma interleukin-1β (IL-1β) and interleukin-6 (IL-6) concentrations and a strong trend ( P = 0.067) for plasma interleukin-1 receptor antagonist concentration during MSVV. Plasma IL-6 concentration was reduced after IMT by 27 ± 18% (main effect of intervention, P = 0.029), whereas there was no change after PLA ( P = 0.753). There was no increase in a systemic marker of oxidative stress [DNA damage in peripheral blood mononuclear cells (PBMC)], and diaphragm fatigue was not related to the increases in plasma IL-1β and IL-6 concentrations. A dose-response relationship was observed between respiratory muscle work and minute ventilation and increases in plasma IL-6 concentration. In conclusion, increases in plasma IL-1β and IL-6 concentrations during MSVV were not due to diaphragm fatigue or DNA damage in PBMC. Increases in plasma IL-6 concentration during MSVV are attenuated following IMT, and the plasma IL-6 response is dependent upon the level of respiratory muscle work and minute ventilation.

The effects of inspiratory muscle training on plasma interleukin-6 concentration during cycling exercise and a volitional mimic of the exercise hyperpnea

It is unknown whether the respiratory muscles contribute to exercise-induced increases in plasma interleukin-6 (IL-6) concentration, if this is related to diaphragm fatigue, and whether inspiratory muscle training (IMT) attenuates the plasma IL-6 response to whole body exercise and/or a volitional mimic of the exercise hyperpnea. Twelve healthy males were divided equally into an IMT or placebo (PLA) group, and before and after a 6-wk intervention they undertook, on separate days, 1 h of 1) passive rest, 2) cycling exercise at estimated maximal lactate steady state power (EX), and 3) volitional hyperpnea at rest, which mimicked the breathing and respiratory muscle recruitment patterns achieved during EX (HYPEX). Plasma IL-6 concentration remained unchanged during passive rest. The plasma IL-6 response to EX was reduced following IMT (main effect of intervention, P = 0.039) but not PLA ( P = 0.272). Plasma IL-6 concentration increased during HYPEX (main effect of time, P < 0.01) and was unchanged postintervention. There was no evidence of diaphragm fatigue (measured by phrenic nerve stimulation) following each trial. In conclusion, plasma IL-6 concentration is increased during EX and HYPEX and this occurred in the absence of diaphragm fatigue. Furthermore, IMT reduced the plasma IL-6 response to EX but not HYPEX. These findings suggest that the respiratory muscles contribute to exercise-induced increases in plasma IL-6 concentration in the absence of diaphragm fatigue and that IMT can reduce the magnitude of the response to exercise but not a volitional mimic of the exercise hyperpnea.