Beyond Reps and Sets: Unlocking the Power of "Time Under Tension" in Vestibular Rehab
(A Substack Article for Vestibular Professionals)
In vestibular rehabilitation, we face a constant challenge: How do we precisely dose exercise for optimal patient outcomes? Unlike the more established guidelines in strength training, with its sets and reps, balance training often relies on subjective measures and arbitrary timeframes. This lack of clarity leaves many therapists and patients wondering about the ideal duration, repetitions, and progression strategies for vestibular exercises.
The Dosage Dilemma
Why do some therapists prescribe gaze stabilization exercises for 1-2 minutes? How many repetitions of a balance exercise are sufficient? My students frequently ask these questions, which have fueled my 26-year quest for answers.
While Klatt et al. (2015) provide a valuable framework for exercise progression, emphasizing patient perception and objective measures of sway and stability, translating this into concrete prescriptions remains challenging. We know that individual factors like the specific vestibular diagnosis, pre-morbid activity level, and symptom response all play a role, but a clear dosage formula remains elusive.
Could "Time Under Tension" Hold the Key?
The answer is borrowing a concept from strength training: time under tension (TUT). In strength training, TUT refers to a muscle is duration under strain during a set. It's a crucial factor influencing muscle adaptation. But how does this apply to balance training?
Think of it this way: just as a muscle adapts to the prolonged stress of lifting a weight, the vestibular and overall balance system might adapt to the cumulative challenge of maintaining balance. Instead of solely focusing on repetitions or individual hold times, we could consider the total duration of vestibular "stress" within an exercise.
My clinical observation of using "three sets of 20-second holds" during baseline balance assessments, totaling one minute of accumulated challenge, has led me to believe in the potential of TUT in vestibular rehab. While designed for evaluation, this protocol inadvertently exposes the vestibular system to a specific dose of destabilizing stimuli. Could this be a model for determining exercise dosage?
Applying TUT in Vestibular Rehabilitation
Here's how we might integrate the TUT concept into our practice:
Cumulative Duration: Instead of prescribing "3 repetitions of 10-second holds," consider prescribing "60 seconds of total hold time, divided into sets with brief rest periods." This allows flexibility in set and rep schemes while maintaining a consistent overall challenge.
Individualized TUT: The optimal TUT might vary based on the patient's condition, symptom severity, and exercise tolerance. Start with a lower TUT and gradually increase it as the patient adapts, similar to progressively overloading a muscle in strength training.
TUT and Exercise Intensity: The relationship between TUT and exercise intensity needs further exploration. A shorter TUT might be sufficient for high-intensity exercises (e.g., standing on foam with eyes closed). A longer TUT might be required for lower-intensity exercises (e.g., single-leg stance on a firm surface).
Monitoring Response: Pay close attention to the patient's subjective feedback and objective measures (sway, stability) throughout the exercise. If symptoms worsen or control deteriorates, reduce the TUT or modify the exercise.
A Proposed Exercise Prescription Framework
Integrating the TUT concept, here's a framework for vestibular exercise prescription:
1. Thorough Assessment:
Identify the specific vestibular impairments.
Assess balance using standardized tests and observe sway patterns.
Gauge the patient's subjective perception of difficulty and symptoms.
2. Exercise Specificity:
Select exercises that directly address the identified impairments.
Incorporate exercises with head movements while fixating on a target for gaze stability.
For postural stability, progress from static to dynamic tasks, manipulating the base of support, surface, and visual input.
3. Embrace TUT:
Consider a cumulative 60-90 seconds per exercise, divided into sets with brief rest periods.
Monitor patient response and adjust accordingly.
4. Systematic Progression:
When the patient reports minimal challenge and demonstrates good control (minimal sway, no loss of balance), consider progressing by:
Increasing TUT.
Narrowing the base of support.
Using a less stable surface.
Adding head movements or a cognitive task.
5. Individualization:
Continuously monitor symptoms and adjust the prescription as needed.
Be patient and flexible, recognizing that progress varies between individuals.
Call to Action:
Incorporating the "time under tension" concept, this framework is a step towards a more standardized and practical approach to exercise prescription in vestibular rehab. Let's move beyond arbitrary durations and embrace a more evidence-informed practice. I encourage fellow vestibular professionals to share their experiences, insights, and research findings to refine our understanding of optimal dosage and maximize patient outcomes.