NCBI ROFL: Apparently, jumping with a weighted vest or springs attached to your shoes is hard.

Effects of loading on maximum vertical jumps: Selective effects of weight and inertia. "A novel loading method was applied to explore selective effects of externally added weight (W), weight and inertia (W+I), and inertia (I) on maximum counter-movement jumps (CMJ) performed with arm swing. Externally applied extended rubber bands and/or loaded vest added W, W+I, and I corresponding to 10-40% of subjects' body mass. As expected, an increase in magnitude of all types of load was associated with an increase in ground reaction forces (GRF), as well as with a decrease in both the jumping performance and power output. However, of more importance could be that discernible differences among the effects of W, W+I, and I were recorded despite a relatively narrow loading range. In particular, an increase in W was associated with the minimal changes in movement kinematic pattern and smallest reduction of jumping performance, while also allowing for ...