Weight-Training Exercises To Counteract the Negative Effects of Low-Protein Diets in People with Kidney Disease

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The summary below is from the full report titled "Resistance Training To Counteract the Catabolism of a Low-Protein Diet in Patients with Chronic Renal Insufficiency." It is in the 4 December 2001 issue of Annals of Internal Medicine (volume 135, pages 965-976). The authors are C Castaneda, PL Gordon, KL Uhlin, AS Levey, JJ Kehayias, JT Dwyer, RA Fielding, R Roubenoff, and MF Singh.

What is the problem and what is known about it so far?

Doctors often recommend low-protein diets for people with kidney disease because such a diet delays the worsening of kidney disease. However, patients who don't eat protein lose muscle. When patients lose enough muscle, they become weak and less able to carry out their usual activities. Lifting weights (resistance training) builds up muscle and reduces loss of muscle in such diseases as HIV infection and congestive heart failure. No one has tested resistance training to see if it prevents loss of muscle in patients with kidney disease who are following a low-protein diet.

Why did the researchers do this particular study?

To find out if lifting weights helps to preserve muscle in patients on a low-protein diet because of kidney disease, which by itself is characterized by muscle loss referred to as muscle wasting.

Who was studied?

The study included 26 adults with kidney disease.

How was the study done?

The researchers assigned patients at random to a low-protein diet plus lifting weights or to a low-protein diet plus sham exercise. Patients assigned to resistance training went three times per week to a special gymnasium where they used five different weight machines. During each exercise session, patients had to do three sets of eight repetitions on each machine. An exercise trainer supervised all exercise sessions. Patients in the sham exercise group did only gentle movements and bending. The sham exercise was designed to have no effect on muscle strength while giving patients the same amount of contact time with the exercise trainer as those in the resistance-training group. The researchers used muscle strength to test the effect of weight training.

What did the researchers find?

After 12 weeks, the patients in the weight-training group gained muscle and muscle strength, while the patients in the sham exercise group became weaker.

What were the limitations of the study?

The authors did not measure the effects of continuing exercise after the 12 weeks of the study.

What are the implications of the study?

Lifting weights (resistance training) appears to help counteract the muscle loss that can occur when people eat a low-protein diet to prevent worsening of kidney disease. Resistance training may help patients with kidney disease to live more normal lives.