You’re seeing a patient with Parkinson’s disease (PD) for dysphagia therapy. Based on her VFSS results and the fact that these patients often have reduced tongue strength, you’re considering lingual strength training as part of her therapy program. But is it as effective for people with PD as it is in other populations? How much of a difference does it make to use a biofeedback device like the IOPI rather than just doing tongue presses against the hard palate? And how many reps and sets should you be recommending, anyway?
 

Plaza and Busanello-Stella’s randomized, controlled study gives us insight into some of these questions. They found that completing lingual exercises plus progressive resistance training with the IOPI resulted in a greater increase in tongue strength and more improvement in self-perceived swallow function compared to performing lingual exercises alone. 

Let’s look at the details.

First, the authors divided participants with PD into two groups. We’ll call them groups A and B. Both groups completed an 8-week therapy program with three sessions per week. In each session, both groups A and B performed the same protocol of 30 ten-second tongue presses against their hard palates and 30 lingual lateralizations. But group B also performed an additional 60 reps of 3-second tongue presses with the IOPI every session. For the IOPI exercises, the authors measured each participant’s maximum tongue pressure, set initial therapy targets based on those maximums, and then systematically increased the target pressures each week. This is the lingual equivalent of lifting heavier weights each week at the gym. 

At the end of the program, both groups increased in tongue strength. The average lingual strength of group A increased by 12%,  and this group also showed a small improvement on the eating duration subset of the SWAL-QOL. So even using a less intense program without a device, the tongue press and range of motion exercises had some effect on lingual strength, and maybe on meals. 

But it turns out that those extra exercises using the IOPI did make a huge difference. While group A had an average increase of 4 kPa over the eight weeks, group B increased by a whopping 13.7 kPA (38%).  And this larger increase brought group B’s (but not group A’s) average maximum pressures into the normal range. What happened when both groups stopped their training? Group B maintained their gains better than group A when tested four weeks later. So on the question of tongue strength alone, the point goes to group B.
 

What about swallowing? The authors assessed swallowing-related outcomes with four subsets of the SWAL-QOL: food selection, eating duration, eating desire, and symptom frequency. Even though the two groups started out with comparable scores in each of these areas, group B performed significantly better than group A in all four areas of the SWAL-QOL after the intervention. Again, group B’s the winner. 

But what caused group B to improve so much more than group A? 

Was it the extra dosage? Group B did complete 3x as many tongue presses. Were the exercises more effective because patients had clear pressure targets to aim for and knew when they hit them? Did the progressively increasing load make the difference? 
 

Unfortunately, based on this study alone, we can’t untangle those factors. But we know from exercise science that biofeedback, dosage, and progressive resistance can all impact strength training outcomes—so we might still consider how to incorporate those factors into our lingual strengthening programs as we’re able. Here are some ideas:

• Biofeedback devices: The IOPI and the lower-cost Tongueometer are two devices that allow patients to see how much lingual force they’re exerting and whether they hit specific targets. There’s another device on the market, the TonguePRESS, which indicates when a patient uses relatively more force but doesn’t show actual pressure values.
• Dosage: Whether or not you have access to a lingual pressure device, you could try replicating the higher dosage (i.e. reps, sets, sessions) of the IOPI group’s protocol when recommending a tongue strengthening program to your patients with PD. See Section 2.3 of the paper for the protocol’s details.
• Progressive resistance: If you’re using a device with your patients, progressive resistance is probably already part of your therapy program. But if you don’t have a device, you could try coaching your patients to rate their own tongue pressure and aim to increase the force in their exercises over time. Last time you were aiming for a level 5 tongue press. This time, let’s aim for a level 6 pressure. While this hasn’t been studied to our knowledge, there’s a chance that trying to make the exercise more progressive without a device might nudge your patients towards better results.

We still need more research to parse out which therapy ingredients have the most impact. But for now, we can say from this study that people with PD might benefit from lingual strength training and that some combination of more reps, progressive resistance, and biofeedback are likely to promote more gains. For more on lingual strength training across populations, check out this open access systematic review that we covered in 2019 (here).

 

Plaza, E., & Busanello-Stella, A. R. (2022) Effects of a tongue training program in Parkinson's disease: Analysis of electrical activity and strength of suprahyoid muscles. Journal of Electromyography and Kinesiology. https://doi.org/10.1016/j.jelekin.2022.102642 [open access]