Taking your sprints to an incline presents a new challenge. As the body masters it, sprinting on a flat surface becomes more easily achieved over time. By substituting hill sprints, you increase fat burning as well as safely stressing the joints in a further stretched position. Keep the results coming by changing things up. Start with five sprints up 50 yards and increase reps and distance
as you improve.
A great exercise for your arms, legs and core is the scissor exercise done while holding a chin. The key is control, to be able to keep your legs bent at 90° and then open and cross repeatedly while holding the chin and 90° leg lift. Start with 5 to 10 per direction, crossing left over right then right over left Increase reps and add sets as you improve.
Burpees have become mainstream, but when you do them the way I say to becomes much more challenging. After kicking your legs back into the push-up position, come back to legs under the body in a hop and immediately leap into a tuck jump. Return down after you land from the tuck jump, and kick back out into the plank or push-up position and repeat for 5 to 10. Increase those reps and sets over time. These take a bit of work to get used to as there is height to achieve as well as form to work for.