PHOTO: Youngsters such as Andrew Chiziver, left, learn their exercises and routines under the watchful eyes of spotter Rene Vachon. Four-year-old Jonathan Perez, right, tries to get the hang of the high bar. / JOEL P. LUGAVERE / Los Angeles Times David Sherman can throw caution to the wind at My Gym-Susi [Yakov Sherman] and Ashley Scott are his gymnastic guardians. / JOE VITTI / Los Angeles Times Three-year-old Jarret Tarnol finds his feet on the parallel bars at Gym for Children in Tarzana. Meanwhile, three's company for, from left, Kristofer Bouchard, Ari Silver and Andrew Chiziver, all age 4. / JOEL P. LUGAVERE / Los Angeles Times Children at a My Gym facility stretch out before exercising. / JOE VITTI / Los Angeles Times Instructor Joel Mills gives Christopher Mann a helping hand. Julie Jacoby, 7, warms up and Ari Silver, 4, gets into the swing of things. / JOEL P. LUGAVERE and JOE VITTI / Los Angeles Times