The purpose of this study was to assess the acute effects of the static and proprioceptive neuromuscular facilitation (PNF) stretching methods on local muscular endurance performance at intensities between 40 and 80% of 1 repetition maximum (1RM) for the knee extension (KE) and bench press (BP) exercises. Fifteen male volunteers (23.9 ± 4.3 years; 174.5 ± 8.5 cm; and 77.8 ± 7.6 kg), who were nonathletes but had previous experience in resistance training, volunteered for this study. Participants were assigned to 9 randomly ordered experimental conditions, in which all subjects performed endurance tests at 40, 60, and 80% of 1RM, preceded by static stretching (SS), PNF, and no stretching (NS) in the KE and BP exercises. One-way repeated-measures analysis of variance (NS × SS × PNF) revealed an influence of stretching for all intensities only when the PNF treatment was used. Significant differences (p < 0.05) were found in the KE exercise, with reductions in the number of repetitions when comparing PNF40 (23.7 ± 2.7) to NS40 (27.5 ± 3.6); PNF60 (12.6 ± 2.8) to SS60 (16.5 ± 4.1) and NS60 (17.3 ± 3.2); and PNF80 (6.3 ± 1.7) to SS80 (9.9 ± 2.5) and NS80 (9.8 ± 2.3) conditions. Significant differences (p < 0.05) were also found for the BP exercise with decreases in the number of repetitions when comparing PNF60 (13.7 ± 2.8) to NS60 (17.0 ± 3.0) and PNF80 (6.2 ± 2.2) to NS80 (8.7 ± 2.3) conditions. These findings suggest that for the intensities studied (40, 60, and 80% 1RM), only the PNF method decreased muscle endurance. Strength and conditioning professionals may want to consider avoiding PNF stretching before activities requiring local muscular endurance performance.

The purpose of this study was to examine the acute effects of 3 different stretching methods combined with a warm-up protocol on vertical jump performance. Sixteen young tennis players (14.5 ± 2.8 years; 175 ± 5.6 cm; 64.0 ± 11.1 kg) were randomly assigned to 4 different experimental conditions on 4 successive days. Each session consisted of a general and specific warm-up, with 5 minutes of running followed by 10 jumps, accompanied by one of the subsequent conditions: (a) Control Condition (CC)-5 minutes of passive rest; (b) Passive Stretching Condition (PSC)-5 minutes of passive static stretching; (c) Active Stretching Condition (ASC)-5 minutes of active static stretching; and (d) Dynamic Stretching Condition (DC)-5 minutes of dynamic stretching. After each intervention, the subjects performed 3 squat jumps (SJs) and 3 countermovement jumps (CMJs), which were measured electronically. For the SJ, 1-way repeated measures analysis of variance (CC × PSC × ASC × DC) revealed significant decreases for ASC (28.7 ± 4.7 cm; p = 0.01) and PSC (28.7 ± 4.3 cm; p = 0.02) conditions when compared with CC (29.9 ± 5.0 cm). For CMJs, there were no significant decreases (p > 0.05) when all stretching conditions were compared with the CC. Significant increases in SJ performance were observed when comparing the DC (29.6 ± 4.9 cm; p = 0.02) with PSC (28.7 ± 4.3 cm). Significant increases in CMJ performance were observed when comparing the conditions ASC (34.0 ± 6.0 cm; p = 0.04) and DC (33.7 ± 5.5 cm; p = 0.03) with PSC (32.6 ± 5.5 cm). A dynamic stretching intervention appears to be more suitable for use as part of a warm-up in young athletes.

Background Foam rolling (FR) is a ubiquitous intervention utilised for the purpose of acutely increasing the range of motion without subsequent decreases in performance. Thus, it is commonly used during the periworkout period—that is, prior to, during, or after an athlete\u27s workout. Objective This study investigated how different FR durations applied to the quadriceps during the interset rest periods affects the numbers of repetitions in the knee extension exercise. Methods Twenty-five females completed four sets of knee extensions with 10 repetitions of maximum load to concentric failure on four occasions. Between each set, a 4-minute rest interval was implemented in which participants either passively rested or performed FR for different durations (60 seconds, 90 seconds, and 120 seconds). The 95% confidence intervals revealed a dose-dependent relationship in which longer durations of FR resulted in fewer completed repetitions. Results On average, the number of repetitions with PR was 13.8% greater than that in FR120, 8.6% greater than that in FR90, and 9.1% greater than that in FR60. Conclusion For the purposes of performance and likely adaptation, interset FR seems to be detrimental to a person\u27s ability to continually produce force, and should not be applied to the agonist muscle group between sets of knee extensions

da Silva Araujo, G, Behm, DG, Monteiro, ER, de Melo Fiuza, AGF, Gomes, TM, Vianna, JM, Reis, MS, and da Silva Novaes, J. Order effects of resistance and stretching exercises on heart rate variability and blood pressure in healthy adults. J Strength Cond Res XX(X): 000-000, 2018-The purpose of this study was to compare the acute effect of different combinations and order of resistance exercise (RE) and stretching exercise (SE) on heart rate variability, systolic blood pressure (SBP), and diastolic blood pressure (DBP). Twenty subjects, recreationally trained, performed 5 sessions in a random order: (a) SE followed by RE no rest (SE + RE), (b) RE followed by SE no rest (RE + SE), (c) SE between RE sets (SBE), (d) SE isolated, and (e) RE isolated. Heart rate variability, SBP, and DBP were collected for 15 minutes before (baseline) and 60 minutes after each experimental session. A significant decrease was found for standardized deviation of differences between adjacent normal r-r intervals (RMSSDms) SE + RE (-50.79%), SE (+9.2%), SBE (-42.8%), and RE (-46.3%). Similarly, a significant increase was found for LFnu in SE + RE (+12.8%) and SBE (+16.6%). In addition, a significant decrease was found for HFnu in SE + RE (-34.8%) and SBE (-39.7%). Finally, a significant decrease was found for SBP in SE (-6.1%). In conclusion, this study indicated that SE followed by RE promotes a reduction in LFnu and RMSSDnu, with trivial to small magnitude decreases in SBP. Therefore, performing SE either before or between RE would be an important exercise prescription recommendation to lower cardiac load and consequently greater safety.