CherieR:
from a post in Exercise:
To avoid overuse injuries, someone has suggested to do multi machine cardio workout as follows (one example):
5 min of elliptical
5 min of running (can be treadmill)
5 min of spinning (static bike)
5 min of slide board (like the reebok one)
5 min of backpack incline walk in treadmill (3.5 mph max)
5 min of rowing.
The order may vary, Supposedly the 30 min done in this way prevent damage to joints etc. from overuse (long continuous use). And provides synergy in the strength and endurance capacities because so many different muscles are used.
In case there is no availability of machines, one can substitute for: rope jump, stair climbing, hill sprints, nordic walking, swimming, or plyometric body weight exercises like: burpees, box jumps, push up position step ups and downs (low platform), etc.
Hope this helps.