Effects of synergistic tongue and chin resistance training on swallowing function, oral intake, and cognitive function in community-dwelling elderly individuals with frailty: a double-blind randomised controlled trial.

BACKGROUND: Tongue strengthening exercises (TSE) and chin tuck against resistance (CTAR) improve swallowing function. However, previous findings are limited to post-stroke population, single-mode therapies, and immediate post-test assessment only, while evidence on effects of combined therapies in community-dwelling elderly individuals with frailty is unknown. Therefore, we explored effects of synergistic TSE and CTAR on swallowing function (tongue strength, swallowing pressure, tongue endurance, and lip strength), oral intake, and cognitive function.

METHODS: A prospective three-arm parallel-group double-blind randomised controlled trial conducted in community residential care facilities. Participants were assigned to TSE + CTAR (n = 31), CTAR (n = 30), or control group: cheek-bulging exercises (n = 30) by block randomisation with block size set at six and sealed opaque envelopes used for allocation concealment. Swallowing training included two phases - (i) initial swallowing training (baseline to 3-month) and (ii) a 3-month booster training initiated immediately after T4 (6-month follow-up) - conducted for 30-minute/session, 3-sessions/d, 6 days/week for 3 months. Outcomes were assessed at 7 time points: baseline, 1-month mid-test, 2-month mid-test, 3-month post-initial training test, 6-month, 9-month, and 12-month follow-up. Data were analysed using generalised estimating equations (GEE) with group, time, and group × time interaction as fixed effects under an intention-to-treat framework.

RESULTS: Ninety-one community-dwelling elderly individuals with frailty (mean age 83.4 ± 6.9 years; 77% women) were enrolled. Significant group × time interactions were observed for tongue strength: anterior tongue strength (ATS) (β = 6.5, 95% CI = 1.6-11.4) and posterior tongue strength (PTS) (β = 8.4, 95% CI = 3.0-13.7) and swallowing pressure saliva swallowing pressure (SSP) (β = 13.3, 95% CI = 8.5-18.2) and effortful swallowing pressure (ESP) (β = 6.2, 95% CI = 0.7-11.7) immediately post-test, with sustained improvements at 9-month and12-month following booster training. Chin tuck against resistance alone produced similar but smaller improvements in tongue strength: ATS (β = 7.8, 95% CI = 3.2-12.4) and PTS (β = 7.0, 95% CI = 2.4-11.5) and swallowing pressure: SSP (β = 13.4, 95% CI = 8.3-18.5), and ESP (β = 8.0, 95% CI = 2.1-13.9) immediate post-test, with sustained improvement at 9-month and 12-month following booster training. Although trends toward better tongue endurance, lip strength, oral intake, and cognitive function were observed, these changes were not statistically significant.

CONCLUSIONS: Synergistic TSE + CTAR, reinforced by booster training, produced statistically significant yet moderate improvement in swallowing function, especially tongue strength and swallowing pressure, compared to CTAR or cheek-bulging exercises alone.

REGISTRATION: Chinese Clinical Trial Registry Identifier: ChiCTR2400091807.