A portable therapeutic leg strengthening apparatus comprising: a longitudinal body (101, 1701, 2602) having first and second ends; a guide member (107, 1709, 2606) moveable between said first and second ends in a direction substantially parallel to a main length of said longitudinal body; a footplate (104, 1711, 2608) pivotally connected to said guide member; a calf support (103, 1713, 2611) connected to said footplate one or a plurality of resiliently biased means (401, 1801, 2614); and a connecting means for connecting (402, 1715, 2613) said one or a plurality of resiliently biased means to said guide member; said one or a plurality of resiliently biased means providing variable resistance to said connecting means to increase or decrease the force required by a user to move said guide member between said first and second ends of said longitudinal body; wherein said footplate and said calf support form a leg rest, configurable between first and second configurations, such that: in said first configuration the leg rest is arranged such that the guide member is pushed against the resistance generated by said one or more resiliently biased means between said first and second ends of the device to exercise the quadriceps and in said second configuration the guide member is pulled against the resistance generated by said one or more resiliently biased means between said first and second ends of the device to exercise the hamstring; and characterised in that the calf support (103, 1713, 2611) is adjustably connected to said footplate (104, 1711, 2608) wherein the apparatus further comprises an adjustment means (111 1714, 2612) for adjusting the angle between said footplate and said calf support. a longitudinal body (101, 1701, 2602) having first and second ends; a guide member (107, 1709, 2606) moveable between said first and second ends in a direction substantially parallel to a main length of said longitudinal body; a footplate (104, 1711, 2608) pivotally connected to said guide member; a calf support (103, 1713, 2611) connected to said footplate one or a plurality of resiliently biased means (401, 1801, 2614); and a connecting means for connecting (402, 1715, 2613) said one or a plurality of resiliently biased means to said guide member; said one or a plurality of resiliently biased means providing variable resistance to said connecting means to increase or decrease the force required by a user to move said guide member between said first and second ends of said longitudinal body; wherein said footplate and said calf support form a leg rest, configurable between first and second configurations, such that: in said first configuration the leg rest is arranged such that the guide member is pushed against the resistance generated by said one or more resiliently biased means between said first and second ends of the device to exercise the quadriceps and in said second configuration the guide member is pulled against the resistance generated by said one or more resiliently biased means between said first and second ends of the device to exercise the hamstring; and characterised in that the calf support (103, 1713, 2611) is adjustably connected to said footplate (104, 1711, 2608) wherein the apparatus further comprises an adjustment means (111 1714, 2612) for adjusting the angle between said footplate and said calf support. in said first configuration the leg rest is arranged such that the guide member is pushed against the resistance generated by said one or more resiliently biased means between said first and second ends of the device to exercise the quadriceps and in said second configuration the guide member is pulled against the resistance generated by said one or more resiliently biased means between said first and second ends of the device to exercise the hamstring; and characterised in that the calf support (103, 1713, 2611) is adjustably connected to said footplate (104, 1711, 2608) wherein the apparatus further comprises an adjustment means (111 1714, 2612) for adjusting the angle between said footplate and said calf support.