The weight restrictions with a fistula or graft are typically told to patients when getting an access and generally relates to allowing the access to heal. I haven't been able to find any research that has stated that lifting weight over any set amount increases the risk of damage to the vascular access. In fact, I've known patients with vascular accesses (fistulas or grafts) who were weightlifters and I worked with an HD patient who did a thousand push ups to prove to himself that he could do it, all with a vascular access. Exercising a fistula is one way to help it mature faster.
Weight lifting restrictions with PD probably have more to do with concerns about hernias. Research has shown that some people are more (or less) prone to hernias than others. One way to limit the risk is to limit intra-abdominal pressure, which can be done by exercising when dry and not using too high PD volumes. Even coughing or straining raise intra-abdominal pressures more than lifting 50 pounds. Here are a couple of abstracts that discuss some things that increase risks in PD patients:
[I]Adv Perit Dial. 2003;19:130-5.
Complications of peritoneal dialysis related to increased intra-abdominal
Mahale AS, Katyal A, Khanna R.
Division of Nephrology, University of Missouri, Columbia, Missouri, USA.
Peritoneal dialysis (PD) is associated with a number of complications, some of which can be attributed to raised intra-abdominal pressure. Intra-abdominal pressure is highest during coughing or straining--activities which, fortunately, are transient. High pressure, primarily due to high volumes of PD solution, can predispose patients to hernias, dialysate leaks, and back pain; it can also cause altered mechanics of breathing. This article reviews those various complications and their management.[/I]
Intraabdominal Pressures during Natural Activities in Patients Treated with Continuous Ambulatory Peritoneal Dialysis
Zbylut J. Twardowski, Ramesh Khanna, Karl D. Nolph, Antonio Scalamogna, Michael H. Metzler, Thomas W. Schneider, Barbara F. Prowant, Leonor P. Ryan
Departments of Medicine and Surgery, University of Missouri, Harry S. Truman Veteran Administration Hospital and Dialysis Clinics, Columbia, Mo., USA
Intraabdominal pressures were measured during natural activities in 6 men, age 24-62 years, treated with continuous ambulatory peritoneal dialysis. The pressures were measured with a pressure transducer secured at the level of the umbilicus in the supine, sitting, and upright positions with 0-3 liters intraperitoneal fluid during talking, coughing, straining, changing position, walking, jogging, exercycling, jumping and weight lifting. Coughing and straining generated the highest intraabdominal pressures in every position. The pressures with weight lifting were proportional to the magnitude of the weight lifted up to 50 lbs, but were lower than those during coughing and straining. The pressures were generally higher with greater intraabdominal fluid volumes, especially with jumping and coughing. Exercycling was associated with lower intraabdominal pressure than was jogging, and the pressures were only minimally influenced by intraperitoneal fluid volumes. The results of this study can be used as a guide in establishing preventive measures in patients with intraperitoneal fluid to decrease complication rates related to raised intraabdominal pressures such as dialysate leaks, hernias and hemorrhoids.[/I]
You can read about exercise for people on dialysis on the Life Options website under free materials. There's even a booklet about prescribing exercise: