The Borg scale is safe and efficacious for prescribing and monitoring self-administered balance and resistance exercise in patients with chronic kidney disease: a post-hoc analysis of RENEXC, a randomized controlled trial.

This is a post-hoc analysis of a single-centre randomized controlled trial. Patients and physiotherapists were not blinded, and the physiotherapists both prescribed exercise and measured outcomes, which may have affected the results. Exercise intensity and duration were self-reported in diaries, so they may be inaccurate. There was no sedentary control group, so the paper cannot show how much exercise improved outcomes compared with no exercise. The Berg Balance Scale had a ceiling effect, so it may not detect change in patients who already scored high. The 30-second sit-to-stand test was the only outcome with an established minimal detectable change in chronic kidney disease, and its improvement did not exceed that minimal detectable change. No minimal detectable change was established for Functional Reach in chronic kidney disease, and the isometric quadriceps strength method has not been evaluated for how accurate or consistent it is. The Borg scale was not previously studied for balance exercise; authors used it to describe levels of challenge and call for additional research. Many patients did not report Borg ratings or exercise duration, and few reached the 90 min/week target.

The authors declare no conflicts of interest. Funding came from Birgit and Sven-Håkan Ohlsson’s Trust; Anna-Lisa and Sven Eric Lundgren’s Trust; the Academy of Health Care Sciences, Skåne University Hospital’s Research Funds, the Kidney Trust, the Swedish Society of Nephrology, and the Swedish Kidney Foundation.

Do not conclude that the Borg scale is validated for balance exercise. The authors extended it to describe levels of challenge and call for additional research.