at least 30 minutes of structured physical activity (adult-led)
  at least 60 minutes unstructured physical activity (free play)

As a general rule, toddlers shouldn't be inactive for more than 1 hour at a time, except for sleeping. That's a lot of work for parents and caregivers, but a lot of much-needed activity for toddlers.

Encourage your toddler to be active, and remember how much he or she is learning along the way.

http://www.aahperd.org/naspe/toddlers.html

"Adopting a physically active lifestyle early in life increases the likelihood that infants and young children will learn to move skillfully," said Dr. Clark. "Promoting and fostering enjoyment of movement and motor skill confidence and competence at an early age will help to ensure healthy development and later participation in physical activity." Dr. Clark (NASPE)


Guidelines for Toddlers and Preschoolers

For toddlers, basic movement skills such as running, jumping, throwing and kicking do not just appear because a child grows older, but emerge from an interaction between hereditary potential and movement experience. These behaviors are also clearly influenced by the environment. For instance, a child who does not have access to stairs may be delayed in stair climbing and a child who is discouraged from bouncing and chasing balls may lag in hand-eye coordination.

Guideline 1.Toddlers should accumulate at least 30 minutes daily of structured physical activity; preschoolers at least 60 minutes.

Guideline 2.Toddlers and preschoolers should engage in at least 60 minutes and up to several hours per day of daily, unstructured physical activity and should not be sedentary for more than 60 minutes at a time except when sleeping.

Guideline 3.Toddlers should develop movement skills that are building blocks for more complex movement tasks; preschoolers should develop competence in movement skills that are building blocks for more complex movement tasks.

Guideline 4.Toddlers and preschoolers should have indoor and outdoor areas that meet or exceed recommended safety standards for performing large muscle activities.

Guideline 5.Individuals responsible for the well-being of toddlers and preschoolers should be aware of the importance of physical activity and facilitate the child's movement skills.
During the preschool years, children should be encouraged to practice movement skills in a variety of activities and settings. Instruction and positive reinforcement is critical during this time in order to ensure that children develop most of these skills before entering school.

"Obesity is a major health problem in children and adolescents. Over the past 20 years, obesity has tripled among adolescents and doubled among children in this country," said Nazrat Mirza, MD, a general pediatrician at Children's National Medical Center, Washington, D.C. "The rapid rise of obesity is due to decreased physical activity and increased sedentary activities such as watching television and computer and video games."
 
According to NASPE Executive Director Judy Young, Ph.D.,

"Because children are not small adults, these activity recommendations are based on the developmental characteristics of children. For instance, children develop skills through involvement in physical activity and parent involvement plays a significant role in children developing motor competence and enjoying physical activity. Only through devoting time to these skills will they become a regular part of a healthy lifestyle. Children and youth who do not participate in adequate physical activity are much more likely to be sedentary as adults than children and youth who are active."

Copies of the full document are available by calling 1-800-321-0789. The cost is $10 for NASPE/AAHPERD members, and $13 for non-members. Stock number is 304-10254.
Information about the National Association for Sport and Physical Education (NASPE) can be found on the Internet at www.aahperd.org, the web site of the American Alliance for Health, Physical Education, Recreation & Dance (AAHPERD). NASPE is the largest of AAHPERD's six national associations. A nonprofit membership organization of over 25,000 professionals in the fitness and physical activity fields, NASPE is the only national association dedicated to strengthening basic knowledge about sport and physical education among professionals and the general public. Putting that knowledge into action in schools and communities across the nation is critical to improved academic performance, social reform and the health of individuals.