Manufacturers of Exersaucers
Evenflo, the manufacturer of Exersaucers, and the makers of other similar toys sell the items as toys to help a child reach developmental milestones. The Evenflo website state that the toys help the children learn to walk and balance and are a fun way to exercise leg muscles.
Dissenting View
There are some concerns about potential downsides to Exersaucers. Pediatricians at Children's Memorial Hospital in Chicago note that the positioning in Exersaucers can cause babies to naturally bend at the knees and dangle toes or to stand stiff-legged and tippy-toed for extended periods of time. Neither of these is a natural posture conducive to the development of good body alignment.
Further Objections
Another concern, according to Children's Memorial, is that babies who spend extended time in Exersaucers might develop a curvy spine and pelvic tilting because of the soft nature of the seating apparatus. If babies are placed upright before they are physically ready, the result--for some children--can be negative and long-lasting, actually delaying the development of walking readiness, according to this report.
Considerations
This doesn't mean parents should toss the Exersaucer out with the trash. Jessica Sepal, a master of physical therapy, notes that placing a baby in an exersaucer can be entertaining and safe, in small doses. Sessions lasting 10-15 minutes, combined with regular time to play on the floor and learn to use muscles naturally, should not cause damage or delay.
Other Considerations
Even if children are not placed in the Exersaucer, the toys covering it can be fun and useful from the outside. A child curious about the various toys can play with them from the outside, cruising the perimeter and using the sides to pull up.
In Conclusion
Exersaucers are a fun toy to be used in short sessions. They don't replace old-fashioned tummy time and floor play for enhancing an infant's development, but using an Exersaucer as a fun diversion for a few minutes at a time is acceptable. Parents looking for a shortcut to early walking should be patient.