To test the hypothesis that an exercise session combined with adequate nutritional supplementation improves skeletal muscle protein accretion during a hemodialysis session.

Inclusion Criteria:

• On hemodialysis for more than 3 months, on a thrice weekly hemodialysis program.
• Adequately dialyzed (Kt/V > 1.2).
• Age 18-75

Exclusion Criteria:

• Pregnant women.
• Patients unable to perform exercise
• Severe unstable underlying disease besides commonly associated with ESRD. Cardiac patients that are stable will be included.
• Patients hospitalized within the last month prior to the study.
• Patients with malfunctioning arterial-venous access (recirculation and/or blood flow < 750 ml/min)
• Patients receiving steroids and/or other immunosuppressive agents.