Effects of Surface-Type Plyometric Training on Physical Fitness in Schoolchildren of Both Sexes: A Randomized Controlled Intervention

SIMPLE SUMMARY: Physical education classes seem to provide an excellent environment to promote health-related physical fitness development and an active lifestyle through the implementation of moderate-to-vigorous physical activity, such as plyometric training (PT). Researchers agree that youth PT approaches can provide a safe and effective conditioning strategy and should be an essential component of fitness, health promotion, and injury prevention programs. It could thus be important to investigate this shortfall within the context of physical education classes and athletic training prescriptions in the untrained school population of different sexes. Thus, the aim of this study was to compare the effects of short-term surface-type PT (firm vs. sand) on physical fitness performances in schoolchildren of both sexes. The data showed that both training surfaces presented greater pre-post changes in all assessed physical variables than non-plyometric programs, which is in concordance with with the accumulated evidence of PT’s effectiveness in improving youth health status. No significant differences in pre-post changes were observed relative to surface type and gender. Since many schools do not have access to sand surfaces, firm surfaces remain the recommendation when PT is envisaged for schoolchildren. ABSTRACT: Plyometric training (PT) has been found to be effective for children’s fitness. However, no study has examined the effects of sex on physical fitness adaptations from surface-type PT in children. This study compared the effects of short-term surface-type PT (firm vs. sand) on the physical fitness of schoolchildren of both sexes. Sixty girls (age = 10.00 ± 1.15 years) and sixty boys (age = 10.02 ± 1.12 years) participated in a short-term (4 weeks), randomized and parallel PT design with pre-to-post measurements. Children were divided into two experimental groups (firm group: PT performed on a clay surface, 20 boys and 20 girls; sand group: PT performed on a dry surface of 20 cm deep sand, 20 boys and 20 girls) and a control group (CG, 20 boys and 20 girls). Squat jump, standing long jump, 20 m sprint, 5-10-5 shuttle, dynamic balance, and maximal aerobic velocity were measured at baseline and after intervention. Both experimental groups showed greater pre-post changes in all assessed variables than the CG (p < 0.0001). No significant differences in pre-post changes were observed relative to surface type or sex (p > 0.05). These findings suggest that a twice-weekly PT program induced physical fitness improvements, which may have transfer to health status during childhood. Additionally, surface type and sex did not affect the training-induced changes in physical fitness.