Haha he fears the jump rope. For jump rope it's less impact on the knees than jogging and is similar enough in muscle requirement to replicate it. Cardio or whole body conditioning is known to boost general energy levels. Boxers that do not do enough jump rope have poor conditioning and poor coordination compared to those that do (generally).
A vinegar mix was the drink of choice for Roman soldiers, reported to give them more energy to train and march and march and march. The roman legion was known for their diligent march training. It was usually watered down with some salt added.
Onion I have personal experience with as generally increasing energy and willingness to exert oneself. I have seen studies where it boosts free testosterone as well. One is in rats and one is a guy in another forum that did blood work before and after eating an onion every day for a couple weeks or a month and found higher levels of free testosterone.
[Purpose] The purpose of this study was to examine the effect of a dance music jump rope exercise on changes Pulmonary Function and body mass index in female overweight subjects in their 20’s. [Subjects and Methods] The subjects were randomly ...
www.ncbi.nlm.nih.gov
Lung function improves moreso with jump rope than cycling.
Study shows that male students going through P.E. regularly AND doing jump rope improve in metrics of speed, VO2 max and body composition moreso than those doing the P.E. lessons alone.
General physical practice and multidimensional exercises are essential elements that allow young athletes to enhance their coordinative traits, balance, and strength and power levels, which are linked to the learning soccer-specific skills. Jumping ...
www.ncbi.nlm.nih.gov
Two groups, one doing soccer specific drills, and the other doing jump rope, shows that the jump rope group developed greater coordination and motor control by their improvement in an agility test while the soccer drill group did not improve after the 8 week study.
Jump rope of course increases bone, tendon and muscle strength in the lower body. Cardio improves muscle function and growth.
All in all jump rope is the way to go for cardio, conditioning and general energy and well-being.