Although a few retrospective case reports noted injury to the growth cartilage in youth, most of these injuries were caused by improper lifting techniques, poorly chosen training loads or lack of qualified adult supervision. For example, in one case report a 13-year-old boy had bilateral fracture separations of the distal radial epiphyses when he lost control of a barbell as he attempted to press a 30 kg weight overhead while exercising alone in a "makeshift gymnasium" at home. It is unclear from this report if this adolescent received instruction on proper resistance training procedures or if he was involved in an activity that could be characterised as "horse play".
Of note, injury to the growth cartilage has not been reported in any prospective youth resistance training study that provided professional guidance and instruction. Furthermore, there is no evidence that resistance training will negatively impact growth in height during childhood and adolescence. The risk of growth plate injury may be greater when young athletes perform jumping and landing activities during competitive sport play that induces ground reaction forces of up to five to seven times body mass.
Although youth resistance training does involve some degree of inherent risk of musculoskeletal injury, this risk does not appear to be any greater than other sports and recreational activities in which children and adolescents regularly participate. Zaricznyj and colleagues evaluated the incidence of sports-related injuries (based on accident reports) in school-age youth over a one-year period and found that resistance training resulted in 0.7% of 1576 injuries, whereas American football resulted in 19% of all injuries. When the data were evaluated in terms of injury to participant ratio in school team sports, American football (28%), wrestling (16%) and gymnastics (13%) were at the top of the list. In support of these observations, more recent data indicate that American football had the highest injury rate (4.36 injuries per 1000 athlete exposures) for nine sports studied.
A related concern regards the performance of plyometric exercises (also called stretch-shortening cycle exercise) for children and adolescents. Although some observers suggested that a predetermined baseline level of strength (eg, 1 RM squat should be 1.5 times body weight) should be a prerequisite for lower body plyometric training, this contention is not supported by current research and clinical observations. Plyometric training can be a relatively safe and effective method of conditioning for children and adolescents if appropriately prescribed and sensibly progressed over time.