**E** ff**ects of Supplementary Strength–Power Training on Neuromuscular Performance in Young Female Athletes**

#### **Konstantina Karagianni, Olyvia Donti, Christos Katsikas and Gregory C. Bogdanis \***

School of Physical Education and Sports Science, National and Kapodistrian University of Athens, 17237 Athens, Greece; karagiannik97@gmail.com (K.K.); odonti@phed.uoa.gr (O.D.); ckatsikas@phed.uoa.gr (C.K.)

**\*** Correspondence: gbogdanis@phed.uoa.gr; Tel.: +30-(210)-7276115

Received: 23 June 2020; Accepted: 22 July 2020; Published: 24 July 2020

**Abstract:** This study examined the e ffects of a short-duration supplementary strength–power training program on neuromuscular performance and sport-specific skills in adolescent athletes. Twenty-three female "Gymnastics for All" athletes, aged 13 ± 2 years, were divided into a training group (TG, *n* = 12) and a control group (CG, *n* = 11). Both groups underwent a test battery before and after 10 weeks of intervention. TG completed, in addition to gymnastics training, a supplementary 7–9 min program that included two rounds of strength and power exercises for arms, torso, and legs, executed in a circuit fashion with 1 min rest between rounds, three times per week. Initially, six exercises were performed (15 s work–15 s rest), while the number of exercises was decreased to four and the duration of each exercise was increased to 30 s (30 s rest) after the fifth week. TG improved countermovement jump performance with one leg (11.5% ± 10.4%, *p* = 0.002) and two legs (8.2% ± 8.8%, *p* = 0.004), drop jump performance (14.4% ± 12.6%, *p* = 0.038), single-leg jumping agility (13.6% ± 5.2%, *p* = 0.001), and sport-specific performance (8.8% ± 7.4%, *p* = 0.004), but not 10 m sprint performance (2.4% ± 6.6%, *p* = 0.709). No change was observed in the CG (*p* = 0.41 to 0.97). The results of this study indicated that this supplementary strength–power program performed for 7–9 min improves neuromuscular and sport-specific performance after 10 weeks of training.

**Keywords:** female; adolescence; resistance training; plyometric training; strength training
