Flywheel eccentric overload exercises versus barbell half squats for basketball players: Which is better for induction of post-activation performance enhancement?

OBJECTIVE: This study compared the post-activation performance enhancement (PAPE) effects of a flywheel eccentric overload (FEOL) exercise and barbell half squats (BHS) on countermovement jump (CMJ) and 30 m sprint performance. METHODS: Twelve male collegiate competitive basketball players were enrolled in this study and they implemented two training protocols: barbell half squat (BHS) and flywheel eccentric overload (FEOL) training. The BHS protocol included three intensities of load: low (40% 1RM), medium (60% 1RM), and high (80% 1RM), with each intensity consisting of 5 sets of 3 repetitions. The FEOL protocol included three inertia intensities: low (0. 015 kg∙m2), medium (0.035 kg∙m2), and high (0.075 kg∙m2), with each intensity consisting of 3 sets of 6 repetitions. The measurement time points were before training (baseline) and at 3, 6, 9, and 12 minutes after training. A two-stage (stage-I and stage-II) randomized crossover design was used to determine the acute effects of both protocols on CMJ and sprint performance. RESULTS: At each training intensity, the jump height, jump peak power output (PPO), jump impulse and 30m sprint speed at 3, 6, 9, and 12 minutes after BHS and FEOL training did not change significantly compared to the baseline. A 2-way ANOVA analysis indicated significant main effects of rest intervals on jump height, jump PPO, and jump impulse, as well as 30m sprint speed. The interaction of the Time × protocol showed a significant effect on jump height between BHS and FEOL groups at high intensity in stage-I (F = 3.809, p = 0.016, df = 4) and stage-II (F = 3.044, p = 0.037, df = 4). And in high training intensity, the jump height at 3 (7.78 ± 9.90% increase, ES = 0.561), 6 (8.96 ± 12.15% increase, ES = 0.579), and 9 min (8.78 ± 11.23% increase, ES = 0.608) were enhanced in I-FEOL group compared with I-BHS group (F = 3.044, p = 0.037, df = 4). In stage-II, the impulse and sprint speed of the FEOL group were significantly higher than those of the BHS group at 6, 9, and 12 min under low (FEOL = 0.015kg∙m2, BHS = 40%1RM), medium(FEOL = 0.035kg∙m2, BHS = 60%1RM), and high (FEOL = 0.075kg∙m2, BHS = 80%1RM) intensities. Furthermore, the sprint speed of the two training protocols did not change at different time points. The interaction of Time × training intensity showed lower sprint speeds in the II-BHS group at a high intensity (BHS = 80%1RM) compared to low (BHS = 40%1RM) and medium (BHS = 60%1RM) training intensities, especially at 9 min and 12 min rest intervals. CONCLUSION: Although barbell half squat training and flywheel eccentric overload training did not provide a significant PAPE effect on explosive power (CMJ and sprint) in male basketball players, FEOL training showed a better potential effect on enhanced CMJ jump performance at the high training intensity.

Comparison of Velocity and Percentage-based Training on Maximal Strength: Meta-analysis.

The purpose was to analyze the comparison of velocity-based resistance training and one-repetition maximum (%1RM) percentage-based training in maximal strength improvement by meta-analyzing and to find the reasons for the controversial findings of different studies. Ten studies were included in the systematic review and seven were subjected to meta-analysis. A total of 139 subjects were selected from the included articles after exclusion, including athletes of different specialties (N=93) and non-athletes mainly from fitness groups (N=46). The overall effect size was SMD=0.26 (95%CL 0.03 to 0.49, P=0.03, I²=0). As for the comparison of the analysis of different intervention objects as subgroups, the effect size of athletes as the subgroup was 0.35 (95%CI 0.06 to 0.64, p=0.02, I²=0), indicating that in the RCT with athletes as the intervention target, the effect of VBRT in improving the maximal strength was significantly different from that of PBT. Velocity-based resistance training might be more effective than percentage-based training in maximal strength improvement, in which velocity-based resistance training is more suitable for athletes in season, while percentage-based training is more suitable for the general sports population. More high-quality researches should deal with the effect of other athletic performance with velocity-based resistance training in the future.

Effects of sprint interval training on maximal oxygen uptake in athletes: a meta-analysis.

INTRODUCTION: To explore the effects of sprint interval training on maximal oxygen uptake (VO2max) in athletes, and whether exercise mode, number of sprints, sprint duration, and interval duration would positively impact on athletes' VO2max, so as to improve the reference of exercise prescriptions. METHODS: A comprehensive search of the literature was conducted using the key words "sprint interval training" and "maximal oxygen uptake" on databases, including both Chinese and English articles published from the establishment of the database to January 2021. The articles were selected by two independent reviewers. The quality of the included studies was evaluated in compliance with the risk-of-bias assessment tool for randomized controlled trials recommended in the Cochrane Handbook. RESULTS: After screening and exclusion, 12 studies were included in the metaanalysis. VO2max in the sprint training group was significantly increased by 2.23 ml/kg/min (95% CI 0.99-3.48; p = 0.987). Subgroup analysis was conducted on exercise type, number of sprints, sprint duration, interval duration, and training period, the results of which showed that VO2max of sprinting-based group was increased by 2.43 ml/kg/min (95% CI 0.41-4.45; p = 0.987); VO2max of sprint duration group 2.27 ml/kg/min (95% CI 0.83-3.71; p = 0.96); VO2max of interval duration < 3 min group 2.39 ml/kg/min (95% CI 0.74-4.03; p = 0.92); VO2max of 8-12 sprints group 2.57 ml/kg/min (95% CI 0.75-4.38; p = 0.96); VO2max of SIT for 3-4 weeks group 2.78 ml/kg/min (95% CI 1.00-4.57; p = 0.96). The funnel plot and Egger's test did not suggest publication bias. CONCLUSIONS: (1) SIT can significantly enhance VO2max in athletes. (2) The training program of 3-week sprinting-based SIT with 8-12, 20-30s sprints and intervals less than 3 min between each sprint is the most significant in improving VO2max in athletes.

Pretreatment of corn cob in [EMIM][OAc] and [EMIM][OAc]/ethanol (water).

High cost and high viscosity of ionic liquid restricted its commercial application in pretreatment of lignocellulose. Water and ethanol were used as additive in [EMIM][OAc] to pretreat corn cob at moderate temperature (< 100 °C). It was found that enzyme hydrolysis (EH) sugar yield was increased with the increase of IL content. The largest EH sugar yield of 68.8% was obtained when pure IL was used. However, for [EMIM][OAc]/ethanol, the EH sugar yield as high as 66.9% was gained when the IL content was 80%, which was comparable to that for pure IL pretreatment. In addition, Kamlet-Taft parameter was calculated to characterize the polarity solvency of binary liquid phase, to illustrate the underlying reason for the increase of EH sugar and the lignin removal. Finally, to demonstrate the crystalline and microstructure change after pretreatment, XRD and SEM were performed for the raw materials and the pretreated samples.