Training effects of the effortful swallow under three exercise conditions

The effortful swallow achieves overload through high effort. It was predicted that both immediate effects on biomechanics and long-term neuromuscular adaptations would be facilitated by maximal overload during this exercise. This study examined how high-effort sips from small-diameter straws influenced linguapalatal swallow pressures. Additionally, training effects of effortful swallows preceded by high-effort sips were compared to two other exercise conditions: effortful swallows preceded by maximum effort lingual elevation and effortful swallows performed in isolation. Training outcomes included linguapalatal pressures produced during effortful and noneffortful swallows, and maximum isometric pressure (MIP) produced during tongue elevation and interlabial compression. Forty healthy adults participated in the experiment. Lingual-palatal swallowing pressure during non effortful and effortful swallows and MIPs were measured prior to and after 4 weeks of training. Prior to training, anterior linguapalatal pressures were significantly higher during effortful compared to noneffortful swallows. Anterior linguapalatal pressures did not significantly differ during swallows preceded by sips from high-resistance straws. Weak correlations were observed between tongue MIP and linguapalatal pressures during effortful swallows. After training, anterior linguapalatal pressures significantly increased, with training effects more dramatic for effortful swallows. Anterior tongue MIP also significantly increased. Gains in anterior linguapalatal pressure were not correlated with gains in tongue MIP. Training effects did not vary across exercise condition. The study failed to find a training advantage of pairing the effortful swallow with a precursor movement. The results demonstrated specificity of training, with more dramatic benefits observed for effortful swallows relative to noneffortful swallows. Further investigation is needed to characterize training effects in older adults and patients with dysphagia.