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The purpose of this study was to determine if successive heavy sets of back squats can augment the concentric velocity of a lighter down set performed by strength-trained men. Twelve trained men with experience in the back squat volunteered to perform a 5 repetition maximum (5RM) along with 2 separate squat sessions consisting of 3 sets of 5 repetitions with 85% of their 5RM. One condition involved performing a "down set" (DS) after the 3 working sets at 85% of 5RM equivalent to 60% of the working-set load that was also performed during the warm-up. A "No down set" condition involved performing an additional warm-up set before the working sets with 60% of the working-set load instead of the down set to determine if velocity was augmented because of postactivation potentiation in the DS condition. In both conditions, 3 minutes of rest was applied between all sets. A paired sample t-test was used to compare the mean concentric velocities (MCVs) of the working sets of both conditions, and a repeated measures analysis of variance was used to assess differences in MCVs between sets performed at 60% of the working-set load. Cohen's d effect sizes were reported for all comparisons, and the critical alpha was set at p # 0.05. No significant differences were observed in the working-set MCVs in both conditions (p 5 0.412, d 5 0.246) or between MCVs in the down set and equivalent warm-up set load in the DS condition (p50.270, d50.002). Although performing a down set may still be efficacious for developing power across a broad spectrum of loads, the results of this study suggest successive heavy sets of back squats do not acutely augment down set concentric velocity in strength-trained men. [ABSTRACT FROM AUTHOR]

This letter addresses a number of discrepancies found in several publications related HMB-FA and ATP supplementation. [ABSTRACT FROM AUTHOR]

The primary purpose of this study was to assess the sensitivity of cell-free DNA (cf-DNA) to different resistance training volume loads. The secondary purpose was to examine the relationship between change in cf-DNA and relative strength. Researchers hypothesized that (a) cf-DNA concentrations would increase with increasing volume load and (b) increases in relative strength would result in predicted decreases to %Δ of cf-DNA. Thirty subjects were recruited for this study, 15 men and 15 women. Blood was collected through venous draws into 4-ml vacutainers at 3 time points: immediately before (T1), after 3 sets (T2), and after 6 sets (T3) of the back squat exercise. A critical alpha of 0.05 was set for inferential statistics. A repeated-measures ANOVA showed that cf-DNA increased significantly from T1 (407.72 ± 320.83) to T2 (1,244.6 ± 875.83) (p < 0.01) and T1 (407.72 ± 320.83) to T3 (1,331.15 ± 1,141.66) (p < 0.01), whereas no difference was found from T2 to T3 (p = 1.00). The linear regression model used to examine the predictive capabilities relative strength had on cf-DNA %Δ from T1 to T3 was found to be significant (p = 0.04; R² = 0.15). The results of this study demonstrate the short response of cf-DNA in relation to variations in resistance training volume load. Results also demonstrated the positive relationship between relative strength and cf-DNA %Δ. The current study builds on the body of research that cf-DNA provides insight regarding the level of immune response after exercise training. [ABSTRACT FROM AUTHOR]

Background: Previous research has explored associations between accelerometry and Global Navigation Satellite System (GNSS) derived loads. However, to our knowledge, no study has investigated the relationship between these measures and a known distance. Thus, the current study aimed to assess and compare the ability of four accelerometry based metrics and GNSS to predict known distance completed using different movement constraints. Method: A correlational design study was used to evaluate the association between the dependent and independent variables. A total of 30 physically active college students participated. Participants were asked to walk two different known distances (DIST) around a 2 m diameter circle (small circle) and a different distance around an 8 m diameter circle (large circle). Each distance completed around the small circle by one participant was completed around the large circle by a different participant. The same 30 distances were completed around each circle and ranged from 12.57 to 376.99 m. Instrumentation: Acceleration data was collected via a tri-axial accelerometer sampling at 100 Hz. Accelerometry derived measures included the sum of the absolute values of acceleration (SUM), the square root of the sum of squared accelerations (MAG), Player Load (PL), and Impulse Load (IL). Distance (GNSSD) was measured from positional data collected using a triple GNSS unit sampling at 10 Hz. Results: Separate simple linear regression models were created to assess the ability of each independent variable to predict DIST. The results indicate that all regression models performed well (R = 0.960–0.999, R2 = 0.922–0.999; RMSE = 0.047–0.242, p < 0.001), while GNSSD (small circle, R = 0.999, R2 = 0.997, RMSE = 0.047 p < 0.001; large circle, R = 0.999, R2 = 0.999, RMSE = 0.027, p < 0.001) and the accelerometry derived metric MAG (small circle, R = 0.992, R2 = 0.983, RMSE = 0.112, p < 0.001; large circle, R = 0.997, R2 = 0.995, RMSE = 0.064, p < 0.001) performed best among all models. Conclusions: This research illustrates that both GNSS and accelerometry may be used to indicate total distance completed while walking. [ABSTRACT FROM AUTHOR]

Travis, SK, Mujika, I, Zwetsloot, KA, Gentles, JA, Stone, MH, and Bazyler, CD. The effects of 3 vs. 5 days of training cessation on maximal strength. J Strength Cond Res 36(3): 633-640, 2022-The purpose of this study was to compare the effects of 3 vs. 5 days of training cessation on body composition, perceived recovery and stress state, and maximal strength. Nineteen strength-trained athletes (23.8 +/- 4.1 year; 90.8 +/- 20.7 kg; 174.2 +/- 7.3 cm) completed a powerlifting specific 4-week training block followed by either 3 or 5 days of training cessation. During the 4-week training block, athletes were trained 3 days per week, performing 3-4 movements that included at least 2-3 competition lifts per session while performing 4-5 sets of 3-5 repetitions with intensity ranging from 75 to 100% 1 repetition maximum (1RM). Body composition, psychometric measures, upper-body maximal strength, and lower-body maximal strength were assessed before (T1) and after 4 weeks of training (T2) and at 3 or 5 days of training cessation (T3). The alpha level was set at p < 0.05. After the 4-week training block (T1 to T2), trivial significant increases in body mass (p = 0.016, Hedge's g = 0.04) and bench press 1RM (p = 0.01, g = 0.16) were observed, as well as small significant increases in back squat 1RM (p < 0.001, g = 0.23), deadlift 1RM (p = 0.003, g = 0.20), powerlifting total (p < 0.001, g = 0.21), and Wilks Score (p < 0.001, g = 0.27). There were no significant differences between groups for isometric back squat performance, psychometric measures, and body composition after training cessation (T2-T3). However, small significant decreases in isometric bench press performance were observed after 5 days (p < 0.001, g = 0.16), but not 3 days of training cessation. The results of this study suggest maximal lower-body strength can be preserved during 3 and 5 days of training cessation, but maximal upper-body strength is only preserved for 3 days after 4 weeks of strength training in athletes. [ABSTRACT FROM AUTHOR]

Travis, SK, Pritchard, HJ, Mujika, I, Gentles, JA, Stone, MH, and Bazyler, CD. Characterizing the tapering practices of United States and Canadian raw powerlifters. J Strength Cond Res 35(12S): S26–S35, 2021—The purpose of this study was to characterize the tapering practices used by North American powerlifters. A total of 364 powerlifters completed a 41-item survey encompassing demographics, general training, general tapering, and specific tapering practices. Nonparametric statistics were used to assess sex (male and female), competition level (regional/provincial, national, and international), and competition lift (squat, bench press, and deadlift). The highest training volume most frequently took place 5–8 weeks before competition, whereas the highest training intensity was completed 2 weeks before competition. A step taper was primarily used over 7–10 days while decreasing the training volume by 41–50% with varied intensity. The final heavy (>85% 1 repetition maximum [1RM]) back squat and deadlift sessions were completed 7–10 days before competition, whereas the final heavy bench press session was completed <7 days before competition. Final heavy lifts were completed at 90.0–92.5% 1RM but reduced to 75–80% 1RM for back squat and bench press and 70–75% for deadlift during the final training session of each lift. Set and repetition schemes during the taper varied between lifts with most frequent reports of 3 × 2, 3 × 3, and 3 × 1 for back squat, bench press, and deadlift, respectively. Training cessation durations before competition varied between deadlift (5.8 ± 2.5 days), back squat (4.1 ± 1.9 days), and bench press (3.9 ± 1.8 days). Complete training cessation was implemented 2.8 ± 1.1 days before competition and varied between sex and competition level. These findings provide novel insights into the tapering practices of North American powerlifters and can be used to inform powerlifting coaches and athlete's tapering decisions. [ABSTRACT FROM AUTHOR]

Caffeine is often used to enhance athletic performance. Caffeine's effects on endurance performance have been thoroughly examined; however, research regarding caffeine's effects on strength and power performance is lacking, especially in female athletes. PURPOSE: To analyze the acute effects of caffeine (6 mg/kg of body mass) on jumping performance and maximal strength in female collegiate athletes. METHODS: Eleven female collegiate athletes performed two testing sessions separated by one week, and randomly received a caffeine (CAF) or placebo (PLA) condition using a double- blind approach. After receiving the CAF of PLA, athletes sat quietly for 60 minutes. Following a standardized warm-up, athletes were assessed on squat jump (SJ) and countermovement jump (CMJ) jump height (JH) and peak power (PP) and isometric mid-thigh pull isometric peak force (IPF) and rate of force development (RFD) on force platforms. A paired samples t-test with Hedge's g (g) effect size was used to compare performance results between conditions. Alpha level for all analyses was set at p<0.05. RESULTS: There were small to moderate differences in SJ-JH (p=0.02,g=0.35), SJ-PP (p=0.005,g=0.77), CMJ-JH (p=0.007,g=0.20), CMJ-PP (p=0.08,g=0.25), IPF (p=0.18,g=0.12), and RFD (p=0.12,g=0.32) in favor of caffeine over placebo. CONCLUSIONS: Caffeine ingestion produced small to moderate improvements in jumping performance; however, caffeine failed to significantly affect maximal strength when compared with the placebo. Therefore, caffeine appears to be an effective ergogenic aid when used to enhance jumping performance, but not maximal strength in female collegiate athletes. Future studies examining such effects should aim to amass a larger sample size, as this is a major limitation to the current body of literature. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate acute effects of match-play on neuromuscular performance and subjective recovery and stress state and the relationship between training load (TL) and changes in neuromuscular performance in female soccer players. Twelve National Collegiate Athlete Association Division I players participated (20.7 ± 2.3 years; 64.4 ± 7.2 kg; 164.5 ± 6.0 cm) and completed countermovement jump (CMJ) at 0 kg (CMJ0) and 20 kg (CMJ20) and the Short Recovery Stress Scale (SRSS) at 3 hours pre-match (Pre), 12 hours post-match (Post12), and 38 hours post-match (Post38). Countermovement jump variables included body mass, jump height (JH), modified reactive strength index (RSI), peak force (PF), relative PF, eccentric impulse, concentric impulse (CI), peak power (PP), relative PP (RPP), eccentric average PP, and concentric average power (CAP). The SRSS consists of 4 Stress Scales (SSs) and 4 Recovery Scales (RSs). Training loads included total distance, total PlayerLoad, high-speed running, and session ratings of perceived exertion. Significant moderate to large decreases were observed from Pre to Post12 in JH, RSI, CI, PP, RPP, and CAP in CMJ0 and CMJ20 (p < 0.05, effect size [ES] = 0.63-1.35). Significant changes were observed from Pre to Post12 in all RSs (p < 0.05, ES = 0.65-0.79) and 3 SSs (p < 0.05, ES = 0.71-0.77). Significant correlations were observed between CMJ20 PP from Pre to Post12 and all TLs (p < 0.05, r520.58 to 20.68). CMJ0 and CMJ20 JH and PP may indicate acute neuromuscular changes after match-play. The magnitude of CMJ20 PP decrements from Pre to Post12 may be affected by soccer match-play volumes. [ABSTRACT FROM AUTHOR]

Strength athletes often implement a tapering protocol to peak prior to major competitions. For less important competitions, strength athletes may use short-term training cessation (i.e., ≤7 days) with the aim of preserving performance. However, the optimal duration of short-term training cessation is still unclear and may have a divergent effect on upper versus lower body maximal strength. PURPOSE: The purpose of this study was to compare the effects of 3 days (3D) versus 5 days (5D) of training cessation on isometric maximal strength in strength athletes. METHODS: Nineteen strength athletes (23.8±4.1y; 90.8±20.7kg; 174.2±7.3cm) completed a powerlifting specific 4-week training block followed by matched-pairs random assignment to 3D or 5D of training cessation. Isometric squat and bench press peak force (IPF) and allometrically scaled peak force (IPFa) were assessed on force platforms before (T1) and after training (T2), and at 3D or 5D of training cessation (T3). A 2x3 mixed ANOVA with post-hoc comparisons and Hedge's g effect sizes were used to assess changes in isometric maximal strength. Alpha criterion was set to p<0.05. RESULTS: A 2x3 mixed ANOVA revealed significant interactions for bench press IPF (p=0.03) and IPFa (p=0.04). Post-hoc comparisons revealed significant increases in bench press IPF (p=0.01,g=0.45) and IPFa (p=0.017,g=0.90) in 3D only following training (T1-T2), whereas bench press IPF (p<0.001,g=0.08) and IPFa (p<0.001,g=0.16) decreased in 5D only following training cessation (T2-T3). No differences were observed in isometric squat metrics for any time point. CONCLUSIONS: Upper body isometric maximal strength is better preserved with 3D of training cessation whereas lower body isometric maximal strength is preserved similarly with 3D or 5D of training cessation in strength athletes. The expression of maximal strength relative to upper body performance capabilities appears to dissipate more rapidly than the lower body after removing the training stimuli. Therefore, sport scientists and strength and conditioning practitioners who use training cessation to promote acute recovery may consider implementing divergent periods of training cessation for the upper and lower body to best preserve performance for maximal strength. [ABSTRACT FROM AUTHOR]