Inter-individual Variability in Responses to 7 Weeks of Plyometric Jump Training in Male Youth Soccer Players

Abstract

The purpose of this study was to compare the inter-individual variability in the effects of plyometric jump training (PJT) on measures of physical fitness (sprint time, change of direction speed, countermovement jump, 20- and 40-cm drop jump reactive strength index, multiple five bounds distance, maximal kicking distance, and 2.4-km time trial) in youth soccer players who completed a PJT program versus players who completed soccer training only. In a single-blinded study, participants aged between 10 and 16 years were randomly divided into a PJT group (n = 38) and a control group (n = 38). The experimental group participated in a PJT program twice weekly for 7 weeks, whereas the control group continued with their regular soccer training sessions. Between-group differences were examined using a Mann–Whitney U test. Nonresponders where defined as individuals who failed to demonstrate any beneficial change that was greater than two times the typical error of measurement from zero. The results indicated that the mean group improvement for all physical fitness measures was greater (p < 0.05) in the PJT group (Δ = 0.4 to 23.3%; ES = 0.04 to 0.58) than in the control group (Δ = 0.1 to 3.8%; ES = 0.02 to 0.35). In addition, a significantly greater (p < 0.05) number of responders across all dependent variables was observed in the PJT group (from 4 up to 33 responders) than in the control group (from 0 up to 9 responders). In conclusion, compared to soccer training only, PJT induced greater physical fitness improvements in youth soccer players, with a greater number of responders for all the physical fitness tests related to jumping, speed, change of direction speed, endurance, and kicking technical ability.

Effects of jump training on jumping performance of handball players: A systematic review with meta-analysis of randomised controlled trials

“…Practitioners are advised to consider general guidelines when formulating JT programmes, according to the current scientific evidence, as well as making them appropriate to the individual(s) with whom they are working. 76–79 Researchers are encouraged to describe how data related to injury, pain, or any other potential adverse effect were collected, clarifying the procedures, definitions and diagnosis by qualified medical practitioners, among other key aspects.…”

Effects of 4 Weeks of a Technique-Specific Protocol with High-Intensity Intervals on General and Specific Physical Fitness in Taekwondo Athletes: An Inter-Individual Analysis

“…have documented increases in general and specific physical fitness using the temporal structure of combat as a work interval in the application of HIIT protocols [ 13 ]; however, the results are still controversial. Another element to consider is that usually the results of sport science interventions are interpreted in group terms, without considering the inter-individual variability of the athletes’ response [ 14 ]. To address this limitation, some authors have dealt with this situation by classifying athletes into two types: responders (Rs) and non-responders (NRs) [ 14 , 15 ].…”

Individual Responses to an 8-Week Neuromuscular Training Intervention in Trained Pre-Pubescent Female Artistic Gymnasts

“…When measuring different expressions of SSC function, selecting a test protocol that represents the specific type of SSC action is recommended, owing to the different mechanisms involved in fast- and slow-SSC activity [14,15,16]. Current methods of examining neuromuscular training interventions on fast-SSC function in youth have included reactive strength index (RSI) and leg stiffness, from drop jumps [17] and hopping tasks [18,19,20].…”