Trial Report Effects of Sub–Symptom Threshold Aerobic Exercise on Persistent Postconcussion Symptom Burden and Exercise Intolerance: [RCT], 2026, Valaas et al

[forestglip]

Effects of Sub–Symptom Threshold Aerobic Exercise on Persistent Postconcussion Symptom Burden and Exercise Intolerance: A Randomized Controlled Trial

Spoiler: Authors

Valaas, Lars-Johan V; Soberg, Helene L; Rasmussen, Mari S; Steenstrup, Sophie E; Brunborg, Cathrine; Røe, Cecilie; Kleffelgård, Ingerid

Importance
Persistent postconcussion symptoms (PCS) following mild traumatic brain injury (mTBI) are common and are often associated with exercise intolerance. The effects of aerobic exercise on PCS in adolescent athletes have been promising. However, randomized controlled trials targeting persistent PCS in the adult population are needed.

Objective
The objective of this study was to evaluate the effects of sub–symptom threshold aerobic exercise (SSTAE) on symptom burden and exercise intolerance in adults with persistent PCS.

Design
This was a randomized (1:1) controlled single-blind, parallel-group trial with follow-up at 12 weeks and 6 months. Setting The setting was a TBI outpatient clinic at Oslo University Hospital, Norway.

Participants
The participants were 81 adults who were 18 to 59 years old and had PCS and exercise intolerance 3 to 24 months after mTBI.

Interventions
The interventions were treatment-as-usual plus SSTAE versus treatment-as-usual including only general exercise information and advice.

Main Outcomes and Measures
The primary outcome was symptom burden, measured with the Rivermead Post-Concussion Symptoms Questionnaire. The secondary outcome was exercise intolerance, measured as the symptom threshold and minutes to stop on the Buffalo Concussion Treadmill Test. Tertiary outcomes were measurements of health-related quality of life, depression, anxiety, fatigue, and level of physical activity.

Results
No between-group differences were observed in the Rivermead Post-Concussion Symptoms Questionnaire at 12 weeks or 6 months. SSTAE significantly improved the Buffalo Concussion Treadmill Test symptom threshold at 12 weeks, with effects sustained at 6 months.

Additionally, the SSTAE group was superior to the control group in minutes to stop at 12 weeks but not at 6 months. No adverse events occurred.

No statistically significant treatment effects were observed for the tertiary outcomes.

Conclusions
The added benefit of SSTAE to treatment-as-usual did not lead to greater reduction in symptom burden compared to the control group.

However, SSTAE significantly improved exercise intolerance and was safe and well tolerated. Both groups improved over time in symptom burden, health-related quality of life, depression, anxiety, and fatigue.

Relevance
Symptom restricted aerobic exercise intervention, provided by physical therapist, improves exercise intolerance in patients with persistent symptoms after mTBI.

Web | DOI | PDF | Physical Therapy | Open Access

 

[forestglip]

However, SSTAE significantly improved exercise intolerance and was safe and well tolerated.

Did it? The abstract makes it seem like a null finding, where exercise was not useful compared to the patients who didn't do exercise. Yet they frame it like exercise was beneficial.

 

[ScoutB]

SSTAE significantly improved the Buffalo Concussion Treadmill Test symptom threshold at 12 weeks, with effects sustained at 6 months.

Staring at their very badly formatted tables -- I think the 'improvement' was that intervention group reached a slightly higher % of their max heart rate before stopping the treadmill test (due to worsening symptoms)?

Agree this does not seem like a relevant benefit.

 

[forestglip]

Ah, I misunderstood the abstract, and thought they were saying that the SSTAE group improved compared to baseline, even though the control group improved just as much. I actually looked at the paper now, and see there was a significant difference compared to controls on the secondary endpoint of the treadmill test:

The between-group treatment effect at 12 weeks favored the SSTAE group (Δ = 5.92 [95% CI = 0.84 to 11.0]; P = .022). At 6 months, the effect was maintained, with a trend toward significance (Δ = 4.98 [95% CI = − 0.20 to 10.15]; P = .059).

Here's the BCTT outcome. Kind of confusing for me.

The secondary outcome was the symptom threshold determined by the BCTT. The test procedure is described in detail in the protocol paper.

Briefly, patients walked on a treadmill at a brisk pace (~5.8 km/h) with the incline increasing by 1% every minute. Once a minute, patients reported symptom types and intensity using a numeric rating scale (score range = 0–10) as well as the Borg Rating of Perceived Exertion (score range = 6–20). At the same time, the assessor recorded heart rate.

The test was stopped when one of the following criteria was met: exercise tolerance, that is, a Borg Rating of Perceived Exertion of ≥18 or >90% of estimated HRmax, without symptom exacerbation; or exercise intolerance, that is, symptom exacerbation, defined as an increase in PCS symptoms of ≥3 points on the numeric rating scale (and +1 for new symptoms).

For patients who were exercise intolerant, the symptom threshold was defined as the heart rate at test cessation and was adjusted relative to the age-estimated HRmax using the following formula: heart rate/[211 − (0.64 × age)] with the minute reached noted as minutes to stop.

Edit: Okay, I was able to parse the text above, and it's not that complicated. Basically, if the patient is walking on a treadmill that is increasing in difficulty with time, what heart rate are they able to achieve before symptoms increase past a certain threshold. As @ScoutB said.

 

[Utsikt]

As each hypothesis was evaluated individually, alpha correction was not applied. 50

The aim of this trial was for all intents and purposes to determine if SSTAE should be used for PCS. The answer is only no if all tests are negative. This is exactly the kind of situation where Rubin (ref 50) argues that alpha adjustment is appropriate:

It is argued that alpha adjustment is only appropriate in the case of disjunction testing, in which at least one test result must be significant in order to reject the associated joint null hypothesis.

 

[rvallee]

So, as is tradition, no meaningful differences in a (poorly, but still) controlled trial, but they recommend it anyway, even though the reasoning is basically "homeopathy, but with ideas", based on seeing improvements in controls that are basically what they usually boast about and isn't really meaningful. Oh, it even features the now fashionable "a trend towards significance".

By "significant", they mean statistically significant, which is not clinically significant. Both groups exceeded clinical significance, but the difference between groups did not. Basically all they're actually doing is trying to justify what they were already doing:

Because physical activity was part of standard care in our clinic at the initiation of the study

They failed at that, but it doesn't matter.

Good stuff. It's like those machines that have a single button where when you press the button an arm opens up to reset the button back to its original setting. Except worse, because they see it as a good idea. Somehow.

And they call this evidence-based medicine.

 

[rvallee]

Did it? The abstract makes it seem like a null finding, where exercise was not useful compared to the patients who didn't do exercise. Yet they frame it like exercise was beneficial.

Not even that, the control group could freely exercise:

Because physical activity was part of standard care in our clinic at the initiation of the study, we considered it ethically inappropriate to restrict physical activity in the control group, narrowing the contrast between the 2 groups, compared to trials using low intensity or stretching-based controls.

Because "ethics". An excuse that would lead to ridicule if it came from unofficial alternative medicine practitioners.