a handle being hollow inside and comprising a connecting rod arranged therein, the connecting rod penetrating through the handle along an axial direction thereof, and opposing ends of the connecting rod respectively extending out from opposing ends of the handle; and

two counterweight adjustment modules symmetrically arranged, connected through a handle, and used for adjusting the load;

wherein the two counterweight adjustment modules are respectively connected to the opposing ends of the connecting rod respectively extending out from the opposing ends of the handle;

each counterweight adjustment module comprises a casing, a transmission adjusting structure, a telescopic sleeve, and a plurality of counterweights, wherein:

the casing is arranged at a corresponding one end of the handle;

the telescopic sleeve is arranged on and can slide along the connecting rod; and

the transmission adjusting structure is arranged inside the casing, and is transmissibly connected with the telescopic sleeve for controlling an extension length of the telescopic sleeve;

wherein the casing comprises an inner casing, an outer casing and a connecting casing; wherein the inner casing is sleeved with the corresponding one end of the connecting rod near the handle, the outer casing is fixedly arranged at the corresponding one end of the connecting rod, and the connecting casing is arranged between the inner casing and the outer casing to realize a fixed connection between the inner and outer casings;

wherein the transmission adjusting structure comprises a knob, a knob gear and a transmission gear; the knob is coaxially and fixedly connected with the knob gear; the transmission gear comprises an upper gear and a lower gear, wherein the upper gear engages with the knob gear and the lower gear is connected with the telescopic sleeve; a latch is arranged on one side of the telescopic sleeve close to the transmission gear for meshing with the lower gear of the transmission gear; the knob gear is connected with the inner casing through a first mounting seat, a first gear lever of the knob gear passes through the first mounting seat, and the knob gear is also fixedly connected with the knob through the first gear lever; the transmission gear is connected with the inner casing through a second mounting seat, and a second gear lever of the transmission gear is mounted on the second mounting seat.