OBJECTIVE To compare the effects of inspiratory resistance training and isocapnic hyperpnoea vs incentive spirometry (placebo) on respiratory function, voice, thorax mobility and quality of life in individuals with tetraplegia. METHODS Randomized controlled trial. METHODS A total of 24 individuals with traumatic, complete tetraplegia (C5-C8, American Spinal Injury Association (ASIA) Impairment Scale; AIS A) were randomly assigned to 1 of 3 groups. They completed 32 supervised training sessions over a period of 8 weeks. Before and after the training period, the following tests were performed: body plethysmography, inspiratory and expiratory muscle strength, subjective breathing parameters using a visual analogue scale, voice measurements, thorax mobility and quality of life. Cohen's effect sizes and Kruskal-Wallis tests for differences between pre- and post-training values were calculated. RESULTS Compared with placebo training, inspiratory resistance training showed high effect sizes for inspiratory muscle strength (d = 1.13), the subjective ability "to blow one's nose" (d = 0.97) and the physical component of quality of life (d = 0.82). Isocapnic hyperpnoea compared with placebo showed a high effect size for breathlessness during exercise (d = 0.81). We found a significant effect of inspiratory resistance training vs placebo (p = 0.016) and vs isocapnic hyperpnoea (p = 0.012) for inspiratory muscle strength. CONCLUSIONS In individuals with motor and sensory complete tetraplegia during the first year post-injury, inspiratory resistance training is more advantageous than isocapnic hyperpnoea, performed 4 times a week for 10 min.