tips for backspots as a rookie

help guys today at cheer camp my bases said i wasn’t lifting enough and the flyer felt much more heavy than usual (context: i just started backspotting at the begin of this summer since i made varsity, but i’ve been cheering for 5 years now). i was doing the same thing i’ve been doing and they said i was very strong and lift a lot, but all of a sudden i lost that strength. cheer camp has also been strenuous so it could be that, but id like any advice to help me really lift the top girl up and take some weight off the bases. should i work on my upper body strength, wrist strength etc? help pls and ty