A prosthetic system comprising: a prosthetic foot (4; 305) including a foot member (6; 306) having a flexible configuration and defining a first end portion (8; 308), a second end portion (10; 310), an intermediate portion (12; 312) defining a curvature and extending between the first and second end portions (8, 10; 308, 310); a pump mechanism (2; 88; 303; 128) coupled to the foot member (6; 306) and positioned between the first and second end portions (8, 10; 308, 310) of the foot member (6; 306), the pump mechanism (2; 88; 303; 128) including a housing (36; 92; 326; 134) defining a cavity, and a membrane (42; 98; 332; 140) situated in the cavity, the pump mechanism (2; 88; 303; 128) movable between an original configuration in which the volume of a fluid chamber defined between the membrane (42; 98; 332; 140) and a bottom of the cavity is zero or near-zero, and an expanded configuration in which the volume of the fluid chamber is increased; and a movable member (34; 90; 322; 132) including a first portion (68; 106; 338; 152) and a second portion (66; 104; 337; 150), wherein the first portion (68; 106; 338; 152) of the movable member (34; 90; 322; 132) is coupled to the membrane (42; 98; 332; 140) and the second portion (66; 104; 337; 150) is arranged to slidably engage the foot member (6; 306), wherein relative movement between the first and second end portions (8, 10; 308, 310) of the foot member (6; 306) moves the first portion (68; 106; 338; 152) of the movable member (34; 90; 322; 132) relative to the housing (36; 92; 326; 134) and slides the second portion (66; 104; 337; 150) of the movable member (34; 90; 322; 132) along a length of the foot member (6; 306) to shift the pump mechanism (2; 88; 303; 128) between the original configuration and the expanded configuration; characterized in that the movable member (34; 90; 322; 132) comprises a plate, and a terminal edge of the first portion (68; 106; 338; 152) defines a slot (70; 108; 342; 154) arranged to receive a connector (44; 102; 334; 142) coupling the movable member (34; 90; 322; 132) to the membrane (42; 98; 332; 140), wherein the connector (44; 102; 334; 142) is arranged to slide within the slot (70; 108; 342; 154) as the first portion (68; 106; 338; 152) of the movable member (34; 90; 322; 152) moves relative to the housing (36; 92; 326; 134). a prosthetic foot (4; 305) including a foot member (6; 306) having a flexible configuration and defining a first end portion (8; 308), a second end portion (10; 310), an intermediate portion (12; 312) defining a curvature and extending between the first and second end portions (8, 10; 308, 310); a pump mechanism (2; 88; 303; 128) coupled to the foot member (6; 306) and positioned between the first and second end portions (8, 10; 308, 310) of the foot member (6; 306), the pump mechanism (2; 88; 303; 128) including a housing (36; 92; 326; 134) defining a cavity, and a membrane (42; 98; 332; 140) situated in the cavity, the pump mechanism (2; 88; 303; 128) movable between an original configuration in which the volume of a fluid chamber defined between the membrane (42; 98; 332; 140) and a bottom of the cavity is zero or near-zero, and an expanded configuration in which the volume of the fluid chamber is increased; and a movable member (34; 90; 322; 132) including a first portion (68; 106; 338; 152) and a second portion (66; 104; 337; 150), wherein the first portion (68; 106; 338; 152) of the movable member (34; 90; 322; 132) is coupled to the membrane (42; 98; 332; 140) and the second portion (66; 104; 337; 150) is arranged to slidably engage the foot member (6; 306), wherein relative movement between the first and second end portions (8, 10; 308, 310) of the foot member (6; 306) moves the first portion (68; 106; 338; 152) of the movable member (34; 90; 322; 132) relative to the housing (36; 92; 326; 134) and slides the second portion (66; 104; 337; 150) of the movable member (34; 90; 322; 132) along a length of the foot member (6; 306) to shift the pump mechanism (2; 88; 303; 128) between the original configuration and the expanded configuration; characterized in that the movable member (34; 90; 322; 132) comprises a plate, and a terminal edge of the first portion (68; 106; 338; 152) defines a slot (70; 108; 342; 154) arranged to receive a connector (44; 102; 334; 142) coupling the movable member (34; 90; 322; 132) to the membrane (42; 98; 332; 140), wherein the connector (44; 102; 334; 142) is arranged to slide within the slot (70; 108; 342; 154) as the first portion (68; 106; 338; 152) of the movable member (34; 90; 322; 152) moves relative to the housing (36; 92; 326; 134).