Objectives: The aim of this study was to analyze the effects of an 8-week (conducted biweekly for a total of 16 sessions) plyometric training program (PT) (e.g., upper- and lower-body exercises) combined with regular tennis training on physical qualities in young tennis players.Design: Sixty tennis players between the ages of 12 and 13 years (age 12.5 ± 0.3 years, weight 44.2 ± 7.0 kg, height 156.6 ± 7.1 cm) were allocated to either the control group (standard in-season regimen) (CG; n = 30) or the experimental group, which received an additional PT (TG; n = 30) for 30–60 min as a substitute for some tennis training within the usual 90-min practice.Methods: Pre- and posttests included: anthropometric measures; vertical countermovement jump (CMJ); standing long jump (SLJ); 20 m sprint time (with 5 and 10 m splits); a modified 505 agility test; overhead medicine ball throw; and serve velocity test.Results: After the training intervention, the TG showed significant (p < .01) improvements in all the parameters analyzed, with percentages of change and effect sizes ranging from 3.1% to 10.1% and 0.4 (small) to 1.3 (moderate), respectively. No significant changes were observed in the CG after the training intervention.Conclusions: PT was shown as an important stimulus for enhancing explosive actions in young tennis players.

Heart rate variability (HRV) has been proposed as a useful marker that can show the performance adaptation and optimize the training process in elite athletes. The development of wearable technology permits the measurement of this marker through smartphone applications. The purpose of this study is to assess the validity and reliability of short and ultra-short HRV measurements in elite cyclists using different smartphone applications. Twenty-six professional cyclists were measured at rest in supine and in seated positions through the simultaneous use of an electrocardiogram and two different smartphone applications that implement different technologies to measure HRV: Elite HRV (with a chest strap) and Welltory (photoplethysmography). Level of significance was set at p < 0.05. Compared to an electrocardiogram, Elite HRV and Welltory showed no differences neither in supine nor in seated positions (p > 0.05) and they showed very strong to almost perfect correlation levels (r = 0.77 to 0.94). Furthermore, no differences were found between short (5 min) and ultra-short (1 min) length measurements. Intraclass correlation coefficient showed good to excellent reliability and the standard error of measurement remained lower than 6%. Both smartphone applications can be implemented to monitor HRV using short- and ultra-short length measurements in elite endurance athletes.

Fernandez-Fernandez, J, Granacher, U, Sanz-Rivas, D, Sarabia Marín, JM, Hernandez-Davo, JL, and Moya, M. Sequencing effects of neuromuscular training on physical fitness in youth elite tennis players. J Strength Cond Res 32(3): 849–856, 2018—The aim of this study was to analyze the effects of a 5-week neuromuscular training (NMT) implemented before or after a tennis session in prepubertal players on selected components of physical fitness. Sixteen high-level tennis players with a mean age of 12.9 ± 0.4 years participated in this study, and were assigned to either a training group performing NMT before tennis-specific training (BT; n = 8) or a group that conducted NMT after tennis-specific training (AT; n = 8). Pretest and posttest included: speed (5, 10, and 20 m); modified 5-0-5 agility test; countermovement jump (CMJ); overhead medicine ball throw (MBT); and serve velocity (SV). Results showed that the BT group achieved positive effects from pretest to posttest measures in speed (d = 0.52, 0.32, and 1.08 for 5, 10, and 20 m respectively), 5-0-5 (d = 0.22), CMJ (d = 0.29), MBT (d = 0.51), and SV (d = 0.32), whereas trivial (10 m, 20 m, CMJ, SV, and MBT) or negative effects (d = −0.19 and −0.24 for 5 m and 5-0-5, respectively) were reported for the AT group. The inclusion of an NMT session before the regular tennis training led to positive effects from pretest to posttest measures in performance-related variables (i.e., jump, sprint, change of direction capacity, as well as upper-body power), whereas conducting the same exercise sessions after the regular tennis training was not accompanied by the same improvements.

Purpose: Road cycling is a sport with extreme physiological demands. Therefore, there is a need to find new strategies to improve performance. Heart-rate variability (HRV) has been suggested as an effective alternative for prescribing training load against predefined training programs. The purpose of this study was to examine the effect of training prescription based on HRV in road cycling performance. Methods: Seventeen well-trained cyclists participated in this study. After an initial evaluation week, cyclists performed 4 baseline weeks of standardized training to establish their resting HRV. Then, cyclists were divided into 2 groups, an HRV-guided group and a traditional periodization group, and they carried out 8 training weeks. Cyclists performed 2 evaluation weeks, after and before a training week. During the evaluation weeks, cyclists performed a graded exercise test to assess maximal oxygen uptake, peak power output, and ventilatory thresholds with their corresponding power output (VT1, VT2, WVT1, and WVT2, respectively) and a 40-min simulated time trial. Results: The HRV-guided group improved peak power output (5.1% [4.5%]; P = .024), WVT2 (13.9% [8.8%]; P = .004), and 40-min all-out time trial (7.3% [4.5%]; P = .005). Maximal oxygen uptake and WVT1 remained similar. The traditional periodization group did not improve significantly after the training week. There were no differences between groups. However, magnitude-based inference analysis showed likely beneficial and possibly beneficial effects for the HRV-guided group instead of the traditional periodization group in 40-min all-out time trial and peak power output, respectively. Conclusion: Daily training prescription based on HRV could result in a better performance enhancement than a traditional periodization in well-trained cyclists.

Purpose:: To compare the effects of combining high-intensity training (HIT) and sport-specific drill training (MT) versus sportspecific drill training alone (DT) on fitness performance characteristics in young tennis players.Methods:: Twenty young tennis players (14.8 ± 0.1 y) were assigned to either DT (n = 10) or MT (n = 10) for 8 wk. Tennis drills consisted of two 16- to 22-min on-court exercise sessions separated by 3 min of passive rest, while MT consisted of 1 sport-specific DT session and 1 HIT session, using 16–22 min of runs at intensities (90–95%) related to the velocity obtained in the 30–15 Intermittent Fitness Test (V_IFT) separated by 3 min of passive rest. Pre- and posttests included peak oxygen uptake (VO₂peak), V_IFT, speed (20 m, with 5- and 10-m splits), 505 Agility Test, and countermovement jump (CMJ).Results:: There were significant improvements after the training period in VO₂peak (DT 2.4%, ES = moderate; MT 4.2%, ES = large) and V_IFT (DT 2.2%, ES = small; MT 6.3%, ES = large) for both DT and MT, with no differences between training protocols. Results also showed a large increase in the 505 Agility Test after MT, while no changes were reported in the other tests (sprint and CMJ), either for MT or DT.Conclusions:: Even though both training programs resulted in significant improvements in aerobic performance, a mixed program combining tennis drills and runs based on the V_IFT led to greater gains and should be considered the preferred training method for improving aerobic power in young athletes.

Purpose: This systematic review with meta-analysis was conducted to establish whether heart rate variability (HRV)-guided training enhances cardiac-vagal modulation, aerobic fitness, or endurance performance to a greater extent than predefined training while accounting for methodological factors. Methods: We searched Web of Science Core Collection, Pubmed, and Embase databases up to October 2020. A random-effects model of standardized mean difference (SMD) was estimated for each outcome measure. Chi-square and the I² index were used to evaluate the degree of homogeneity. Results: Accounting for methodological factors, HRV-guided training was superior for enhancing vagal-related HRV indices (SMD₊ = 0.50 (95% confidence interval (CI) = 0.09, 0.91)), but not resting HR (SMD₊ = 0.04 (95% CI = −0.34, 0.43)). Consistently small but non-significant (p > 0.05) SMDs in favor of HRV-guided training were observed for enhancing maximal aerobic capacity (SMD₊ = 0.20 (95% CI = −0.07, 0.47)), aerobic capacity at second ventilatory threshold (SMD₊ = 0.26 (95% CI = −0.05, 0.57)), and endurance performance (SMD₊ = 0.20 (95% CI = −0.09, 0.48)), versus predefined training. No heterogeneity was found for any of the analyzed aerobic fitness and endurance performance outcomes. Conclusion: Best methodological practices pertaining to HRV index selection, recording position, and approaches for establishing baseline reference values and daily changes (i.e., fixed or rolling HRV averages) require further study. HRV-guided training may be more effective than predefined training for maintaining and improving vagal-mediated HRV, with less likelihood of negative responses. However, if HRV-guided training is superior to predefined training for producing group-level improvements in fitness and performance, current data suggest it is only by a small margin.