I recently read an article posted on parents.com about baby development that touted the benefits of exersaucers and Jonny Jumps. Let me put an end to that notion right now. While I understand the necessity of such devices for small periods of time (meal preps and bathroom breaks can be near impossible without them), these devices should in no way substitute free play on the ground or be used as a way to “strengthen” young children’s legs.
For the remainder of this article I am discussing devices that support the pelvis while the legs are in a weight-bearing to semi-weight-bearing position, including but not limited to: jumpers, exersaucers, sit-and play walkers.
The Dangers of Jumpers, Exersaucers, and Sit-and-Play Walkers
Places Children in Weight-Bearing Position before Muscles are Ready
When a child is not physically strong enough to support their body weight in a standing position, they will assume a position of flexion (knees bent, hips and trunk bent forward). If the child is pulling to stand at a stable surface, this weakness may result in a collapse at the knees or a fall backward. However, when a child is strapped into a device supporting their pelvis and trunk, they are unable to drop to the floor. Instead the child assumes a semi-weight bearing flexed position. Many advertisements for such devices depict the child in this flexed semi-weight bearing position.
Teaches Weight-Bearing through Balls of Feet (rather than heels)
Many times children will bear weight through the balls of their feet while in these devices. Usually because the device is not adjusted to the appropriate height and the child is trying to reach the ground, or the child is not strong enough and is in a flexed position while trying to reach the ground. Repetitive weight bearing through the forefoot creates a motor learning pattern that can be continued on into regular gait. We call this types of walking, through the forefoot, toe-walking.
Poor Alignment of Lower Extremity
The semi-weight bearing flexed position that children may assume when placed in sustained weight bearing before their muscles are mature enough for standing has already been described above. This position can result in: 1) excessive stain and force through the pelvis to support the trunk, or 2) excessive hip external rotation, excessive knee flexion and weight bearing through lateral knee, and/or excessive weight bearing with ankles in maximum plantar flexion(toes pointed down). Excessive time in these abnormal positions can lead to a multitude of musculoskeletal problems later on, including: toe-walking, hip stabilizer weakness, increased falls, knee pain, out-toeing.
To limit the negative effects of jumpers, it is recommended that children spend no more than 20 minutes a day in them. In fact, time spent in all positioning devices should be limited to a total of 30 minutes per day to allow for optimal gross motor development.
