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University makes claim on anti-gravity treadmill, then runs away from evidence

Anti-gravity treadmills get patients running again after knee surgery

Our Review Summary

Researchers in the UK presented a single case study of a 39-year-old runner who had surgery on her knee followed by physical therapy using a special treadmill. The release claimed the “anti-gravity” treadmill, which reduces the pressure of weight on the knee, helped this patient reduce fears about re-injury and increase their confidence in their ability to run again. The release did not provide any data to support that claim.

The release would have been stronger had it included a mention of the cost and availability of anti-gravity treadmills. They’re very expensive pieces of equipment but are becoming more widely available through rehabilitation clinics.


Why This Matters

Knee pain is a very common condition and often keeps people from activities, including exercise, that are known to promote overall health. This news release about a single patient’s recovery from surgery overstates the benefit of the “anti-gravity” treadmill by implying that because this patient recovered better after using the machine, that others might, too. Studying a single patient, without comparison to a control group, cannot prove this treadmill improves outcomes. As we’ve said in a recent blog post, case studies should not be used as proof of health outcomes.


Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

The release makes no mention of costs of the “space age” treadmill device. We found at least one anti-gravity treadmill has been around since 2005. The machines sell for between $24,500 and $70,000. Most people who would want to use them would be referred to a rehabilitation clinic where it may cost about $80 to run on one for 55 minutes.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The release does not offer any units of measurement to describe the benefits. The descriptions of benefits also lean pretty heavily on abstractions that are tricky to measure.

In the following example, the benefits are “a great environment for healing” and “belief” that a patient can make a successful return.

“Not only does the tailored anti-gravity treadmill programme provide a great environment for healing, it also helps the person restore their belief that they can make a successful return to the sport they love.”

In another example, the researcher is paraphrased as saying the machine could be helping to “reduce fears about re-injury and increase self-belief.” Basically they are saying that the runner re-gained some confidence in running. This cannot be extended to generalizations about health outcomes.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

The release does not mention any potential harms.

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

As we outlined in benefits above, this release is written about a single case study of a single patient. The reader does not have enough information about the evidence to judge the quality.  The release does not explain how the study measured the patient’s attitude or knee recovery. We’re only told that the therapy last 8 weeks.

We did look at the published study which explained the measurements. But they aren’t included in the release.

Does the news release commit disease-mongering?


There was no disease mongering.

Does the news release identify funding sources & disclose conflicts of interest?

Not Satisfactory

The release doesn’t say if the author received funding to complete the case study. It also doesn’t give readers any information about potential conflicts of interest, or the absence of any, between the study authors and anti-gravity treadmill manufacturers.

Does the news release compare the new approach with existing alternatives?

Not Satisfactory

The release doesn’t mention any alternatives to the treadmill for people needing rehabilitation after knee surgery.

The release is about a study of a single patient who pursued a single rehab journey following surgery. Besides that limitation, the news release also missed an opportunity to mention that there are non-surgical approaches to treating cartilage damage in the knee.

Does the news release establish the availability of the treatment/test/product/procedure?

Not Satisfactory

The release does not tell us whether the device is available anywhere outside of the specific physical therapy facility profiled in the case study.

Does the news release establish the true novelty of the approach?

Not Satisfactory

The release doesn’t tell us how this case study yields anything new beyond the previous research completed on anti-gravity treadmills used in rehabilitation.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?


We did not find unjustifiable language — just exaggeration.

Total Score: 2 of 10 Satisfactory


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