Maximal effort lifts are to be avoided in all child populations and most youth populations.
According to the ASCA the following training loading intensities and exercise selection strategies be adopted when training child and youth populations:
Level 1: 6-9 years of age: modification of body weight exercises and light resistance work only for relatively high repetitions e.g. 15+ repetitions.
Level 2: 9-12 years of age: 10-15 RM; (maximal loading approximately 60% maximum) using predominantly simple free weight exercises and machine exercises where the machine is an appropriate size for the child.
Level 3: 12-15 years of age: 8-15 RM; (maximal loading approximately 70% maximum) using progressively more free weight exercises but avoiding complex lifts such as cleans, snatches, deadlifts and squats etc. unless competent coaching is available from a coach with at least a Level 2 ASCA coach.
Level 4: 15-18 years of age: 6-15 RM; (maximal loading approximately 80% maximum) progressively moving towards an advanced adult program involving split routines, where appropriate, and complex multi-joint movements, provided sound technique has been developed under competent coaching by a coach with at least Level 2 ASCA accreditation.
For noting: The above maximal loading percentages relate to strength-based exercises (e.g., bench press) and not to velocity specific exercises such as medicine ball throws where higher percentages may apply.