NmR Spectroscopy is used to study the metabolic changes associated with exercise in the flexor muscle of the forearm of human volunteers. Isometric exercise at variable workloads as well as constant workload are carried out using a hand dynamometer which is interfaced to a personal computer and a display unit. Changes in phosphocreatine (PCr) and inorganic phosphate (Pi) as well as intracellular pH are monitored via 31p NMR spectroscopy during the exercise. Age-related differences in these parameters during exercise are studied in subjects of the BLSA using these protocols.