Effects of Inspiratory Muscle Training on Muscle Oxygenation during Vascular Occlusion Testing in Trained Healthy Adult Males

Inspiratory muscle training (IMT) may have an additional effect on cardiovascular autonomic modulation, which could improve the metabolism and vascular function of the muscles. Aim: To determine the effects of IMT on vascular and metabolic muscle changes and their relationship to changes in physical performance. Methods: Physically active men were randomly placed into an experimental (IMTG; n = 8) or IMT placebo group (IMTPG; n = 6). For IMT, resistance load was set at 50% and 15% of the maximum dynamic inspiratory strength (S-Index), respectively. Only the IMTG’s weekly load was increased by 5%. In addition, both groups carried out the same concurrent training. Besides the S-Index, a 1.5-mile running test, spirometry, and deoxyhemoglobin (HHb(AUC) during occlusion) and reperfusion tissue saturation index (TSI(MB) and TSI(MP): time from minimum to baseline and to peak, respectively) in a vascular occlusion test were measured before and after the 4-week training program. In addition, resting heart rate and blood pressure were registered. Results: IMTG improved compared to IMTPG in the S-Index (Δ = 28.23 ± 26.6 cmH(2)O), maximal inspiratory flow (MIF: Δ = 0.91 ± 0.6 L/s), maximum oxygen uptake (Δ = 4.48 ± 1.1 mL/kg/min), 1.5-mile run time (Δ = −0.81 ± 0.2 s), TSI(MB) (Δ = −3.38 ± 3.1 s) and TSI(MP) (Δ = −5.88 ± 3.7 s) with p < 0.05. ΔVO(2max) correlated with S-Index (r = 0.619) and MIF (r = 0.583) with p < 0.05. Both ΔTSI(MB) and TSI(MP) correlated with ΔHHb(AUC) (r = 0.516 and 0.596, respectively) and with Δ1.5-mile run time (r = 0.669 and 0.686, respectively) with p < 0.05. Conclusion: IMT improves vascular function, which is related to additional improvements in physical performance.