The Relationship Between Cell-Free DNA and Resistance Training Volume Load.

ABSTRACT: Lang, HM, Duffourc, MM, Bazyler, CD, Ramsey, MW, and Gentles, JA. The relationship between cell-free DNA and resistance training volume load. J Strength Cond Res 38(6): 1008-1012, 2024-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.

The difference between several neuromuscular tests for monitoring resistance-training induced fatigue.

The purposes of this study were to investigate the acute effects of resistance training protocol on kinetic changes in squat jump (SJ), shortened isometric mid-thigh pull (IMTP), and isometric squat (ISQ) and to examine the relationship of dynamic maximum strength with performance changes over 48 hours in resistance-trained individuals. Participants completed performance tests at pre-, post-24 hours, and post-48 hours resistance training protocol (Baseline, Post24, and Post48). The training protocol consisted of 5 sets of 10 repetitions of back squat (BSQ) at 60% of 1 repetition maximum (1RM). SJ variables included jump height (JH), peak power (PP), and relative PP. For the IMTP and ISQ, isometric peak force (IPF), relative IPF, rate of force development at 250 milliseconds (RFD250), and impulse at 250 milliseconds (IMP250) were calculated. Significant decreases were observed from Baseline to Post24 (p = 0.023, Cohen's dz effect size [dz] = 1.00) and Post48 (p = 0.032, dz = 0.94) in SJ JH. IMTP IMP250 significantly decreased from Baseline to Post48 (p = 0.046, dz = 0.88). Significant negative correlation was found between relative 1RM BSQ and the changes from Baseline to Post48 in ISQ RFD250 (p = 0.046,r = -0.61). Acute performance decreases might remain until 48 hours after resistance training in explosive strength and impulse regardless of isometric testing type.

Intrasession and Intersession Reliability of Isometric Squat, Midthigh Pull, and Squat Jump in Resistance-Trained Individuals.

ABSTRACT: Ishida, A, Suarez, DG, Travis, SK, Slaton, JA, White, JB, Bazyler, CD, and Stone, MH. Intrasession and intersession reliability of isometric squat, midthigh pull, and squat jump in resistance-trained individuals. J Strength Cond Res 37(1): 18-26, 2023-The purposes of this study were to investigate intrasession and intersession reliability of variables obtained from squat jump (SJ), shortened isometric midthigh pull (IMTP), and isometric squat (ISQ) protocols and to evaluate relationships between isometric and dynamic performance and 1 repetition maximum (1RM) back squat (BSQ). Eleven moderately resistance-trained men participated (27.8 ± 3.9 years; 175.0 ± 7.2 cm; 87.2 ± 11.4 kg). Subjects completed familiarization in the IMTP and ISQ, followed by 1RM BSQ at least 48 hours before the first performance test. Two performance tests occurred at 7-day intervals including SJ, IMTP, and ISQ. SJ variables included jump height (SJH), body mass (BM), peak force (PF), and peak power (PP). Isometric midthigh pull and ISQ variables included isometric peak force (IPF); relative IPF; rate of force development at 90, 200, and 250 milliseconds; and impulse at 90, 200, and 250 milliseconds. SJ, IMTP, and ISQ kinetic variables were considered reliable if intraclass correlations (ICCs) and coefficients of variations (CVs) were >0.80 and <10%. Intrasession and intersession reliability criteria were met for SJH, BM, PF, and PP (ICC = 0.91-1.00, CV = 0.5-9.1%). Isometric peak force and impulse at 200 and 250 milliseconds met intrasession and intersession reliability criteria for IMTP and ISQ (ICC = 0.90-0.99, CV = 2.1-8.1%). Significant large correlation was observed between 1RM BSQ and ISQ peak force (p = 0.038, r = 0.63), but not between 1RM BSQ and shortened IMTP peak force (p = 0.11, r = 0.50). Shortened IMTP and ISQ peak force and impulse are reliable kinetic variables, and ISQ peak force is indicative of 1RM BSQ in moderately resistance-trained men.

The Relationship between Accelerometry, Global Navigation Satellite System, and Known Distance: A Correlational Design Study.

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.

The Effects of 3 vs. 5 Days of Training Cessation on Maximal Strength.

ABSTRACT: 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.

Acute Effects of Match-Play on Neuromuscular and Subjective Recovery and Stress State in Division I Collegiate Female Soccer Players.

ABSTRACT: Ishida, A, Bazyler, CD, Sayers, AL, Mizuguchi, S, and Gentles, JA. Acute effects of match-play on neuromuscular and subjective recovery and stress state in Division I collegiate female soccer players. J Strength Cond Res 35(4): 976-982, 2021-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, r = -0.58 to -0.68). 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.

Characterizing the Tapering Practices of United States and Canadian Raw Powerlifters.

ABSTRACT: 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.

Preparing for a National Weightlifting Championship: A Case Series.

Travis, SK, Mizuguchi, S, Stone, MH, Sands, WA, and Bazyler, CD. Preparing for a national weightlifting championship: A case series. J Strength Cond Res 34(7): 1842-1850, 2020-This study aimed to characterize psychological, physiological, and performance changes of a high-level female (24.5 years; 53.8 ± 0.3 kg; 155.4 cm) and male (25.8 years; 92.7 ± 1.2 kg; 189 cm) weightlifter over 28 weeks while preparing for a national championship. Body mass, hydration, psychological inventories, serum biomarkers, vastus lateralis muscle cross-sectional area (CSA), and squat jump (SJ) performance were assessed weekly beginning 11 weeks from the competition date. Weightlifting performance goals were met for the female athlete (actual total = 159 kg) but not for the male athlete (actual total = 292 kg). Reductions in vastus lateralis CSA possibly took place the week leading into competition for both athletes. Both athletes reported positive recovery-stress states on the day of competition relative to baseline values. Fluctuations between steroid hormone concentrations and inflammatory markers were unpredictable and inconsistent for both athletes throughout the training program. Unloaded SJ height and rate of force development were the highest on competition day for both athletes. Based on these findings, it is possible for high-level male and female weightlifters to achieve and maintain peak preparedness 3-4 days before competition following a 1-week overreach and 3-week exponential taper, where training volume-load is reduced by half and intensity maintained or slightly increased relative to pretaper values. Furthermore, the short recovery and stress scale and SJ testing seem to be useful tools for sport scientists and coaches when monitoring high-level weightlifters preparing for competition.

Body Mass and Femur Length Are Inversely Related to Repetitions Performed in the Back Squat in Well-Trained Lifters.

Cooke, DM, Haischer, MH, Carzoli, JP, Bazyler, CD, Johnson, TK, Varieur, R, Zoeller, RF, Whitehurst, M, and Zourdos, MC. Body mass and femur length are inversely related to repetitions performed in the back squat in well-trained lifters. J Strength Cond Res 33(3): 890-895, 2019-The purpose of this research note was to examine whether relationships existed between anthropometrics (body mass, body fat percentage [BF%], and femur length) and descriptive characteristics (age and sex) with repetitions performed to failure at 70% of 1 repetition maximum (1RM) in the back squat. Fifty-eight subjects (males = 43, females = 15; age: 23 ± 3 years, training age: 5.5 ± 2.5 years, body mass: 80.65 ± 16.34 kg, BF%: 10.98 ± 3.53%, and femur length: 47.1 ± 2.6 cm) completed a 1RM squat followed by one set to failure at 70% of 1RM. Total repetitions performed at 70% of 1RM were 14 ± 4 (range: 6-26). Bivariate correlations showed significant inverse relationships between body mass (r = -0.352, p = 0.003), BF% (r = -0.278, p = 0.014), and femur length (r = -0.265, p = 0.019), with repetitions performed. No significant relationships existed between age and sex (p > 0.05), with repetitions performed. All these variables entered into a standard multivariate regression. The model R was 0.200, and body mass had the largest influence (p = 0.057) because relative importance analysis demonstrated body mass to contribute to 43.87% of the variance (of the R) in repetitions performed. No other variable was significant or approached significance (p > 0.05). Our results reveal that body mass, BF%, and femur length all are inversely related to repetitions performed at 70% of 1RM in the back squat.

Jumping Performance is Preserved but Not Muscle Thickness in Collegiate Volleyball Players After a Taper.

Bazyler, CD, Mizuguchi, S, Sole, CJ, Suchomel, TJ, Sato, K, Kavanaugh, AA, DeWeese, BH, and Stone, MH. Jumping performance is preserved but not muscle thickness in collegiate volleyball players after a taper. J Strength Cond Res 32(4): 1020-1028, 2018-The purpose of this study was to examine changes in muscle architecture and jumping performance in NCAA division I women's volleyball players throughout a competitive season and in preparation for conference championships. Ten women volleyball players were tested at preseason (T1), pretaper (T2), and post-taper (T3) on measures of vastus lateralis muscle thickness (MT), pennation angle (PA) and fascicle length (FL) using ultrasonography, and unloaded and loaded squat jump height (SJH) and peak power allometrically scaled to body mass (SJPPa) on a force platform. Rating of perceived exertion training load and strength training volume load were monitored weekly. Player's MT (p < 0.001, Glass's Δ = 2.8) and PA increased (p = 0.02, Δ = 3.9) after in-season training. However, MT decreased after the taper (p = 0.01, Δ = 0.6) but remained elevated above preseason values (p < 0.001, Δ = 1.7). There were no statistical changes in FL, SJH, or SJPPa. Large-to-very large negative relationships (r = -0.51 to -0.81) were observed between preseason relative maximal strength and changes in SJH and SJPPa with various loads over the season. These findings demonstrate that relatively low volumes of strength training and concurrent sport training during a tapering period are capable of preserving jumping performance, but not MT in women's volleyball players; however, jumping performance changes seem to be related to the player's strength level. Stronger players may benefit from an overreaching microcycle before the taper to preserve previously accrued muscular adaptations and jumping performance.

Characteristics of a National Level Female Weightlifter Peaking for Competition: A Case Study.

Bazyler, CD, Mizuguchi, S, Zourdos, MC, Sato, K, Kavanaugh, AA, DeWeese, BH, Breuel, KF, and Stone, MH. Characteristics of a national level female weightlifter peaking for competition: A case study. J Strength Cond Res 32(11): 3029-3038, 2018-This study investigated physiological and performance changes of a national-level 69 kg female weightlifter after 3 competition phases over a 28-week training period. The athlete first trained for a regional championship (weeks 1-12), followed by a local competition (weeks 13-23) and the national championship (weeks 24-28). Body mass, vastus lateralis cross-sectional area (CSA), and unloaded and loaded squat jump performance were assessed weekly during each 4-week competition phase. Serum biomarkers and dynamic midthigh pulls were assessed before and after each competition phase. Weightlifting performance goals were met for the regional championship (total = 200 kg) and the local competition (total = 193 kg), but not the national championship (total = 196 kg). She lost more body mass in preparation for Nationals (-6.0 kg) compared with regionals (-2.5 kg) and the local competition (+2.2 kg). Vastus lateralis CSA very likely decreased after Nationals (precision = 99%, effect size = 2.08). Her testosterone:cortisol ratio likely increased (88%, 2.64), whereas interleukin-6 (79%, 2.47) and tumor necrosis factor-alpha (81%, 3.59) likely decreased after Nationals. Serum myostatin (99%, 1.95) and decorin (99%, 1.96) very likely decreased after the local competition. Unloaded squat jump height likely increased the week of regionals (89%, 0.95) and the local competition (99%, 1.83), whereas unloaded and loaded squat jump height possibly (69%, 0.99) and likely (82%, 1.52) decreased the week of Nationals. Dynamic midthigh pull vertical displacement likely increased after regionals (93%, 0.84) and likely decreased after Nationals (94%, 0.87). These findings indicate that biomarkers of stress, inflammation, and hypertrophy are related to changes in training volume-load; however, performance measures are needed to assess competition preparedness. Considering the reductions in muscle CSA corresponding with the large reductions in body mass and underperformance at the national championship, sport scientists, and coaches should instruct weightlifters to not attempt large losses in body mass (e.g., >3 kg) close to competition (e.g., <1week).

Changes in Muscle Architecture, Explosive Ability, and Track and Field Throwing Performance Throughout a Competitive Season and After a Taper.

The purpose of this study was to examine the effects of an overreach and taper on measures of muscle architecture, jumping, and throwing performance in Division I collegiate throwers preparing for conference championships. Six collegiate track and field throwers (3 hammer, 2 discus, 1 javelin) trained for 12 weeks using a block-periodization model culminating with a 1-week overreach followed by a 3-week taper (ORT). Session rating of perceived exertion training load (RPETL) and strength training volume-load times bar displacement (VLd) were recorded weekly. Athletes were tested pre-ORT and post-ORT on measures of vastus lateralis architecture, unloaded and loaded squat and countermovement jump performance, underhand and overhead throwing performance, and competition throwing performance. There was a statistical reduction in weight training VLd/session (d = 1.21, p ≤ 0.05) and RPETL/session (d = 0.9, p ≤ 0.05) between the in-season and ORT training phases. Five of 6 athletes improved overhead throw and competition throwing performance after the ORT (d = 0.50, p ≤ 0.05). Vastus lateralis muscle thickness statistically increased after the in-season training phase (d = 0.28, p ≤ 0.05) but did not change after the ORT. Unloaded countermovement jump peak force and relative peak power improved significantly after the ORT (d = 0.59, p ≤ 0.05, d = 0.31, p ≤ 0.05, respectively). These findings demonstrate that an overreaching week followed by a 3-week taper is an effective means of improving explosive ability and throwing performance in collegiate track and field throwers despite the absence of detectable changes in muscle architecture.

The use of the isometric squat as a measure of strength and explosiveness.

The isometric squat has been used to detect changes in kinetic variables as a result of training; however, controversy exists in its application to dynamic multijoint tasks. Thus, the purpose of this study was to further examine the relationship between isometric squat kinetic variables and isoinertial strength measures. Subjects (17 men, 1-repetition maximum [1RM]: 148.2 ± 23.4 kg) performed squats 2 d · wk(-1) for 12 weeks and were tested on 1RM squat, 1RM partial squat, and isometric squat at 90° and 120° of knee flexion. Test-retest reliability was very good for all isometric measures (intraclass correlation coefficients > 0.90); however, rate of force development 250 milliseconds at 90° and 120° seemed to have a higher systematic error (relative technical error of measurement = 8.12%, 9.44%). Pearson product-moment correlations indicated strong relationships between isometric peak force at 90° (IPF 90°) and 1RM squat (r = 0.86), and IPF 120° and 1RM partial squat (r = 0.79). Impulse 250 milliseconds (IMP) at 90° and 120° exhibited moderate to strong correlations with 1RM squat (r = 0.70, 0.58) and partial squat (r = 0.73, 0.62), respectively. Rate of force development at 90° and 120° exhibited weak to moderate correlations with 1RM squat (r = 0.55, 0.43) and partial squat (r = 0.32, 0.42), respectively. These findings demonstrate a degree of joint angle specificity to dynamic tasks for rapid and peak isometric force production. In conclusion, an isometric squat performed at 90° and 120° is a reliable testing measure that can provide a strong indication of changes in strength and explosiveness during training.

The efficacy of incorporating partial squats in maximal strength training.

The purpose of our study was to examine the effects of 2 different training methods on dynamic and isometric measures of maximal strength. Seventeen recreationally trained men (1 repetition maximum [1RM] squat: 146.9 ± 22.4 kg) were assigned to 2 groups: full range of motion (ROM) squat (F) and full ROM with partial ROM squat (FP) for the 7-week training intervention. Repeated measures analysis of variance revealed that there was a statistically significant group-by-time interaction for impulse scaled at 50, 90, and 250 milliseconds at 90° of knee flexion and rate of force development at 200 milliseconds with 120° of knee flexion (p ≤ 0.05). There was also a statistically significant time effect (p ≤ 0.05) for the 1RM squat, 1RM partial squat, isometric squat peak force allometrically scaled (IPFa) 90°, IPFa 120°, and impulse allometrically scaled at 50, 90, 200, and 250 milliseconds at 90° and 120° of knee flexion. Additionally, the FP group achieved statistically larger relative training intensities (%1RM) during the final 3 weeks of training (p ≤ 0.05). There was a trend for FP to improve over F in 1RM squat (+3.1%, d = 0.53 vs. 0.32), 1RM partial squat (+4.7%, d = 0.95 vs. 0.69), IPFa 120° (+5.7%, d = 0.52 vs. 0.12), and impulse scaled at 50, 90, 200, and 250 milliseconds at 90° (+6.3 to 13.2%, d = 0.50-1.01 vs. 0.30-0.57) and 120° (+3.4 to 16.8%, d = 0.45-1.11 vs. 0.08-0.37). These larger effect sizes in the FP group can likely be explained their ability to train at larger relative training intensities during the final 3 weeks of training resulting in superior training adaptations. Our findings suggest that partial ROM squats in conjunction with full ROM squats may be an effective training method for improving maximal strength and early force-time curve characteristics in men with previous strength training experience. Practically, partial squats may be beneficial for strength and power athletes during a strength-speed mesocycle while peaking for competition.

Convergent Validity of the Short Recovery and Stress Scale in Collegiate Weightlifters.

The purpose of this study was to determine whether changes in collegiate weightlifters' external training load, biochemical markers, and jumping performance correlate to changes in items of the Short Recovery and Stress Scale (SRSS) throughout four microcycles. Twelve well-trained weightlifters (8 males, 4 females; age 24.30 ± 4.36 yr; height 170.28 ± 7.09 cm; body mass 81.73 ± 17.00 kg) with at least one year of competition experience participated in the study. Measurements included hydration, SRSS, biochemical analysis of blood (cortisol [C], creatine kinase [CK]), and unloaded and loaded squat jumps (SJ), and volume-load displacement. Pearson correlation coefficients were calculated between the changes in SRSS items and all other variables. The alpha criterion for all analyses was set at p ≤ 0.05. Negative relationships were observed between changes in SRSS recovery items and C (r = -0.608 to -0.723), and unloaded and loaded SJ height and peak power (r = -0.587 to -0.636). Positive relationships were observed between changes in several SRSS stress items and C (r = 0.609 to 0.723), CK (r = 0.922), and unloaded and loaded SJ height and peak power (r = 0.583 to 0.839). Relationships between changes in some SRSS items and cortisol agree with previous findings highlighting C as an indicator of training stress. Nonetheless, the non-significant relationships between changes in SRSS items, training volume and biochemical markers disagree with previous findings. This may partly be explained by the smaller undulations in training volume in the current study, which were characteristic of typical training. Further, relationships between changes in some SRSS items and jumping performance were opposite of what was expected indicating athletes' perception of their stress and recovery state does not always correspond with their ability to perform.

Accuracy of Predicting One-Repetition Maximum from Submaximal Velocity in The Barbell Back Squat and Bench Press.

This study examined the accuracy of predicting a free-weight back squat and a bench press one-repetition maximum (1RM) using both 2- and 4-point submaximal average concentric velocity (ACV) methods. Seventeen resistance trained men performed a warm-up and a 1RM test on the squat and bench press with ACV assessed on all repetitions. The ACVs during the warm-up closest to 1.0 and 0.5m.s-1 were used in the 2-point linear regression forecast of the 1RM and the ACVs established at loads closest to 20, 50, 70, and 80% of the 1RM were used in the 4-point 1RM prediction. Repeated measures ANOVA and Bland-Altman and Mountain plots were used to analyze agreement between predicted and actual 1RMs. ANOVA indicated significant differences between the predicted and the actual 1RM for both the 2- and 4-point equations in both exercises (p<0.001). The 2-point squat prediction overestimated the 1RM by 29.12±0.07kg and the 4-point squat prediction overestimated the 1RM by 38.53±5.01kg. The bench press 1RM was overestimated by 9.32±4.68kg with the 2-point method and by 7.15±6.66kg using the 4-point method. Bland-Altman and Mountain plots confirmed the ANOVA findings as data were not tightly conformed to the respective zero difference lines and Bland-Altman plots showed wide limits of agreement. These data demonstrate that both 2- and 4-point velocity methods predicted the bench press 1RM more accurately than the squat 1RM. However, a lack of agreement between the predicted and the actual 1RM was observed for both exercises when volitional velocity was used.

Weight Selection Attempts of Elite Classic Powerlifters.

This study provides the first comparison of weight selection attempt strategies used by powerlifters competing at the international level. We observed attempts selected by elite male and female classic powerlifters and compared weight selection attempts between sexes. Male (n = 66) and female (n = 43) powerlifters who completed all lifts successfully at an International Powerlifting Federation Classic World Championship between 2012-2019 were included in the analysis. We calculated the percentage weight increase from first attempts (A1) to second attempts (A2) and from A2 to third attempts (A3). For purposes of comparison, A1 values were expressed as a percentage of A3 values. We calculated non-parametric statistics with effect sizes for between and within-group comparisons. Relative to A3, males selected greater A1s compared to females for bench press (η2 = 0.16; p = 0.004) and deadlift (η2 = 0.06; p = 0.036) for each lift. Alternatively, females selected greater A1 to A2 and A2 to A3 progressions for bench press (η2 = 0.06; p = 0.026; η2 = 0.21; p = 0.005, respectively), and A2 to A3 for deadlift (η2 = 0.04; p = 0.035) compared to males. Within-group comparisons showed that males selected greater A1s on bench press compared to deadlift (η2 = 0.06; p = 0.046), whereas females selected greater A1s on squat compared to deadlift (η2 = 0.13; p = 0.038) relative to A3. Males also selected greater A2 to A3 progressions on deadlift compared to bench press (η2 = 0.10; p = 0.044), whereas females selected greater A2 to A3 progressions for bench press (η2 = 0.15; p = 0.039) and deadlift compared to squat (η2 = 0.10; p = 0.041). In conclusion, selecting an opener of ∼91% of the expected A3 weight, followed by ∼5% increase from A1 to A2, and ∼3% increase from A2 to A3 represent the typical weight selection attempts used across lifts by elite classic powerlifters competing in the World Championships. The results of this study provide novel insight into the weight selection attempts of elite classic powerlifters.

Skeletal Muscle Adaptations and Performance Outcomes Following a Step and Exponential Taper in Strength Athletes.

Before major athletic events, a taper is often prescribed to facilitate recovery and enhance performance. However, it is unknown which taper model is most effective for peaking maximal strength and positively augmenting skeletal muscle. Thus, the purpose of this study was to compare performance outcomes and skeletal muscle adaptations following a step vs. an exponential taper in strength athletes. Sixteen powerlifters (24.0 ± 4.0 years, 174.4 ± 8.2 cm, 89.8 ± 21.4 kg) participated in a 6-week training program aimed at peaking maximal strength on back squat [initial 1-repetition-maximum (1RM): 174.7 ± 33.4 kg], bench press (118.5 ± 29.9 kg), and deadlift (189.9 ± 41.2 kg). Powerlifters were matched based on relative maximal strength, and randomly assigned to either (a) 1-week overreach and 1-week step taper or (b) 1-week overreach and 3-week exponential taper. Athletes were tested pre- and post-training on measures of body composition, jumping performance, isometric squat, and 1RM. Whole muscle size was assessed at the proximal, middle, and distal vastus lateralis using ultrasonography and microbiopsies at the middle vastus lateralis site. Muscle samples (n = 15) were analyzed for fiber size, fiber type [myosin-heavy chain (MHC)-I, -IIA, -IIX, hybrid-I/IIA] using whole muscle immunohistochemistry and single fiber dot blots, gene expression, and microRNA abundance. There were significant main time effects for 1RM squat (p < 0.001), bench press (p < 0.001), and deadlift, (p = 0.024), powerlifting total (p < 0.001), Wilks Score (p < 0.001), squat jump peak-power scaled to body mass (p = 0.001), body mass (p = 0.005), fat mass (p = 0.002), and fat mass index (p = 0.002). There were significant main time effects for medial whole muscle cross-sectional area (mCSA) (p = 0.006) and averaged sites (p < 0.001). There was also a significant interaction for MHC-IIA fiber cross-sectional area (fCSA) (p = 0.014) with post hoc comparisons revealing increases following the step-taper only (p = 0.002). There were significant main time effects for single-fiber MHC-I% (p = 0.015) and MHC-IIA% (p = 0.033), as well as for MyoD (p = 0.002), MyoG (p = 0.037), and miR-499a (p = 0.033). Overall, increases in whole mCSA, fCSA, MHC-IIA fCSA, and MHC transitions appeared to favor the step taper group. An overreach followed by a step taper appears to produce a myocellular environment that enhances skeletal muscle adaptations, whereas an exponential taper may favor neuromuscular performance.

Seasonal Changes and Relationships in Training Loads, Neuromuscular Performance, and Recovery and Stress State in Competitive Female Soccer Players.

Background: The purpose of this study was to examine seasonal changes in training load (TL), neuromuscular performance, subjective recovery, and stress state, and to investigate the relationships between acute and chronic TL and neuromuscular performance in competitive female soccer players. Methods: Nine competitive female soccer players (20.0 ± 1.7 years; 60.3 ± 6.3 kg; 164.0 ± 5.8 cm) completed the Short Recovery and Stress Scale and the countermovement jump (CMJ) with polyvinyl chloride pipe (CMJ0) and 20 kg barbell (CMJ20) at 2-3 h before 1st match (NC1), 6th match (NC2), 9th match (C1), and 15th match (C2) of the competitive season. TL included total distance, high-speed running, and PlayerLoad. Acute and chronic TL was calculated by using the average of 2 days (D2), 7 days (D7), and 21 days (D21) prior to four different match play. Results: Significant decreases were found from NC1 to C1 in D7 total distance [p = 0.03, Cohen's effect size (dz) = 1.40]. D7 total distance and PlayerLoad significantly decreased from NC to C1 and C2 (p = 0.001-0.01, dz = 1.40-1.72). Significant increases were observed from NC1 to C1 in CMJ0 jump height (p = 0.03, dz = 1.40), (p = 0.021, dz = 1.44), and peak power (p = 0.03, dz = 1.32). Significant negative correlations were observed for D7 total distance and CMJ0 jump height (p = 0.02, r = 0.79) and peak power (p = 0.03, r = 0.71) at C2, while significant positive correlations were observed at C1 for D7 PlayerLoad and CMJ0 jump height (p = 0.02, r = 0.80). Conclusion: Polyvinyl chloride pipe (CMJ0) jump height and peak power may increase from preseason to the midcompetitive season. Seasonal variations may affect the relationships between D7 TL and CMJ0 performance.

The Effects of Caffeine on Jumping Performance and Maximal Strength in Female Collegiate Athletes.

Caffeine is often used in a variety of forms to enhance athletic performance; however, research regarding caffeine's effects on strength and power in female athletes is lacking. Therefore, the purpose of this study was to analyze the acute effects of caffeine anhydrous (6 mg/kg of body mass) on jumping performance and maximal strength in female collegiate athletes. Eleven athletes (19.7 ± 0.9 yrs; 166.4 ± 10.2 cm, 67.7 ± 9.4 kg) performed two testing sessions separated by one week, and randomly received caffeine or placebo using a double-blind approach. Heart rate, blood pressure, and tympanic temperature were recorded before athletes received each condition, following 60 min of quiet sitting, and directly after performance testing. Athletes were assessed on unweighted and weighted squat jump height (SJH0, SJH20) and countermovement jump height (CMJH0, CMJH20), isometric mid-thigh pull peak force (IPF), and rate of force development from 0-200 ms (RFD200). Resting systolic blood pressure was significantly greater following caffeine administration compared to a placebo (p = 0.017). There were small, significant differences in SJH0 (p = 0.035, g = 0.35), SJH20 (p = 0.002, g = 0.49), CMJH0 (p = 0.015, g = 0.19), and CMJH20 (p < 0.001, g = 0.37) in favor of caffeine over placebo. However, there was no significant difference in IPF (p = 0.369, g = 0.12) and RFD200 (p = 0.235, g = 0.32) between conditions. Therefore, caffeine appears to enhance jumping performance, but not maximal strength in female collegiate athletes.