The purpose of this study was to investigate the effect of inspiratory muscle (IM) warm-up on performance and locomotor muscle oxygenation during high-intensity intermittent sprint cycling exercise. Ten subjects performed identical exercise tests (10 × 5 s with 25-s recovery on a cycle ergometer) after performing one of two different IM warm-up protocols. The IM warm-up consisted of two sets of 30 inspiratory efforts against a pressure-threshold load equivalent to 15 % (PLA) or 40 % (IMW) of maximal inspiratory pressure (MIP). MIP was measured with a portable autospirometer. Peak power and percent decrease in power were determined. Oxyhemoglobin (O2Hb) was measured using near-infrared spectroscopy. The MIP increased relative to baseline after IMW (115 ± 21 vs. 123 ± 17 cmH2O, P = 0.012, ES = 0.42), but not after PLA (115 ± 20 vs. 116 ± 17 cmH2O). Peak power (PLA: 10.0 ± 0.6 vs. IMW: 10.2 ± 0.5 W kg(-1)), percent decrease in power (PLA: 13.4 ± 5.6 vs. IMW: 13.2 ± 5.5 %), and changes in O2Hb levels (PLA: -10.8 ± 4.8 vs. -10.7 ± 4.1 μM) did not differ between the trials. IM function was improved by IMW. However, this did not enhance performance or locomotor muscle oxygenation during high-intensity intermittent sprint cycling exercise in untrained healthy males.
Keywords: Inspiratory muscle fatigue; Near-infrared spectroscopy; Repeated-sprint; Respiratory muscle; Team sports.