Turner, L. A., Tecklenburg-Lund, S., Chapman, R. F., Stager, J. M., Duke, J. W., & Mickleborough, T. D. (2012). The effect of IMT on muscle deoxygenation during exercise with resistive inspiratory loading. Presentation 2240 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

This study determined the effect of inspiratory muscle training on respiratory and limb locomotor muscle deoxygenation during exercise while undergoing periods of increased inspiratory loading. Male cyclists completed six weeks of inspiratory muscle training using an inspiratory load of 50% (N = 8) or 15% (placebo/control; N = 8) of maximal inspiratory pressure. Pre- and post-training, Ss completed three, 6-minute experimental trials in a randomized order, separated by 20 minutes. Each trial exercise intensity was equivalent to ~80% VO2max (EX80%); during the final three minutes of each trial Ss received an intervention consisting of; (1) moderate resistive inspiratory loading, (2) heavy resistive inspiratory loading, or (3) maximal exercise. Limb locomotor or respiratory muscle oxy-, deoxy-, and total-hemoglobin concentrations were continuously monitored using near-infrared spectroscopy.

Maximal inspiratory pressure was significantly increased from pre- to post- training by 26 ± 19% in the inspiratory muscle training group and remained unchanged in the placebo/control group. Following inspiratory muscle training, a significant reduction in the change in oxygen uptake, limb locomotor, and respiratory muscles was observed when moving from EX80% to heavy inspiratory loading (submaximal exercise). There was no significant difference in muscle oxy-, deoxy-, and total-hemoglobin during any of the other loading trials, from pre- to post-training, in either group.

Implication. After inspiratory muscle training, highly-trained competitive cyclists demonstrated decreased whole-body oxygen uptake, and limb-locomotor or respiratory-muscle deoxygenation during exercise with heavy inspiratory loading. Inspiratory muscle training reduced respiratory muscle demand and decreased oxygen extraction by the active muscles, which may reflect inspiratory-muscle training-induced changes in respiratory and limb locomotor muscle oxygen delivery.

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