The dynamic strength index is a reliable and feasible tool to assess neuromuscular performance in male and female handball players.

The aim of this study was to explore the reliability and feasibility of the isometric mid-thigh pull (IMTP) and dynamic strength index (DSI) in semi-professional handball players (seventeen male and eighteen female). A cross-sectional design was used to determine the test-retest reliability of several kinetic metrics registered with a force plates. The peak force, peak relative force, rate of force development (RFD 0-250 ms), and impulse 0-250 ms were selected from the IMTP test, whereas the peak propulsive force was chosen from the countermovement jump test to obtain the DSI. The intraclass correlation coefficient (ICC), coefficient of variation (CV), standard error of the measurement (SEM) and smallest detectable difference (SDD) were calculated. A paired sample t-test was also performed. No significant differences were found between the testing sessions for all variables, except for peak propulsive force for all players (p = 0.036) and DSI for female players (p = 0.037). Reliability for all kinetic metrics was good to excellent (ICC = 0.78-0.97), with low variability (CV ≤ 8.64%), being the SEM scores lower than SDD. In conclusion, the IMTP test and DSI are highly reliable and feasible tools for assessing neuromuscular performance in semi-professional handball players.

"You Are Not Wrong About Getting Strong:" An Insight Into the Impact of Age Group and Level of Competition on Strength in Spanish Football Players.

OBJECTIVE: This study aimed to compare the maximum and rapid force production of Spanish football players and explore the differences between age group and level of competition. METHODS: A cross-sectional study was developed to evaluate the peak force (PF), relative PF, and rate of force development over 250 ms (RFD0-250) during the isometric midthigh pull between groups of football players based on age group (senior vs junior) and level of competition (national vs regional). Using a portable isometric rig, 111 football players performed 2 isometric midthigh-pull trials on a force plate. Two-way analysis of variance with Bonferroni post hoc correction was applied, and statistical significance was set at P ≤ .05. The PF, relative PF, and RFD0-250 0, 25, 50, 75, and 100 percentiles were also calculated and descriptively reported, separated by age group and level of competition. RESULTS: The analysis of variance revealed a significant main effect of the level of competition for the PF (P < .001), relative PF (P = .003), and RFD0-250 (P < .001). There was a significant main effect of age group for the PF (P < .001). There was a significant interaction effect of the age group × level of competition for relative PF (P = .014). National players were stronger than regional players on the PF and RFD0-250 (P < .001). Senior players were stronger than junior players for the PF (P < .001). CONCLUSIONS: Maximum and rapid force production are crucial for Spanish football players as they progress in both level of competition and age group. Practitioners should encourage young football players to prioritize strength development to improve their athletic performance.

The 8:1:1 Supplementation of Branched-Chain Amino Acids in High-Intensity Training: A Case Study of the Protective Effect on Rhabdomyolysis.

INTRODUCTION: The increasing prevalence of high-intensity sports activities, notably the burgeoning popularity of CrossFit, underscores the contemporary significance of such physical pursuits. The discernible protective impact of branched-chain amino acids on muscle fatigue and injuries is emerging as a noteworthy area of investigation. Within the realm of sports, integrating BCAA supplementation into dietary practices holds promise for aiding athletes in their recovery, particularly in mitigating Delayed-Onset Muscle Soreness. METHODOLOGY: This study adopted an experimental pilot design with repeated measures, employing a controlled and randomized approach through double-blind procedures. The participant engaged in high-intensity activity, specifically the CrossFit Karen® test, which entailed executing 150 wall ball throws (9 kg) to a height of 3 m. The trial incorporated three randomized supplementation conditions: BCAAs in an 8:1:1 ratio or a 2:1:1 ratio or a placebo condition. The participant consumed 15 g daily for 7 days, commencing 72 h prior to the initial blood sample and the first Karen® test. RESULTS: In this study, BCAA supplementation at an 8:1:1 ratio demonstrated a discernible protective effect against muscular damage, as evidenced by creatine kinase values and ratings of perceived exertion.

A single dose of dihydrocapsiate does not improve neuromuscular performance in resistance-trained young adults: A randomised, triple-blinded, placebo-controlled, crossover trial.

Capsinoids may exert ergogenic effects on resistance exercises. However, the acute effects of capsinoids on neuromuscular performance in humans are unknown. Here, we aimed to investigate the acute effects of dihydrocapsiate on lower- and upper-body neuromuscular performance parameters in resistance-trained individuals. 25 young adults (n = 6 women; age = 26 ± 3 years; body mass index = 24.3 ± 2.8 kg/m2) with ≥ 1-year resistance training experience were included in this triple-blind (participants, intervention researchers, and data analysts were blinded), placebo-controlled, crossover study. Lower- and upper-body ballistic strength (countermovement jump [CMJ] height and bench press throw [BPT] peak velocity), maximum dynamic strength (estimated 1 repetition maximum in squat and bench press [BP]), and strength-endurance (mean set velocity [squat] and number of repetitions to failure [bench press]) were assessed in 2 independent sessions (≥7 days separation). Participants ingested 12 mg of dihydrocapsiate or placebo 30 min before each trial. We found no significant differences between dihydrocapsiate and placebo conditions in ballistic strength, (CMJ height 33.20 ± 8.07 vs 33.32 ± 7.85 cm; BPT peak velocity 2.82 ± 0.77 vs 2.82 ± 0.74 m/s) maximal dynamic strength (estimated squat 1RM: 123.76 ± 40.63 vs 122.66 ± 40.97 kg; estimated BP 1RM: 99.47 ± 43.09 vs 99.60 ± 43.34 kg), and strength-endurance (squat mean set velocity 0.66 ± 0.07 vs 0.66 ± 0.05 m/s; number BP repetitions to failure 13.00 ± 3.56 vs 13.00 ± 4.78) (all P ≥ 0.703). We conclude that dihydrocapsiate does not acutely improve neuromuscular performance in trained young adults.

Capsinoids ­ non-pungent analogs of capsaicin ­ have been recently proposed as potential ergogenic compounds in humans.However, the effects of a single dose of capsinoids on neuromuscular performance parameters in humans remains unknown.12 mg of dihydrocapsiate does not improve neuromuscular performance in resistance-trained young adults.Dihydrocapsiate should not be recommended as an ergogenic aid to acutely increase neuromuscular performance.

National Strength and Conditioning Association Position Statement on Weightlifting for Sports Performance.

ABSTRACT: Comfort, P, Haff, GG, Suchomel, TJ, Soriano, MA, Pierce, KC, Hornsby, WG, Haff, EE, Sommerfield, LM, Chavda, S, Morris, SJ, Fry, AC, and Stone, MH. National Strength and Conditioning Association position statement on weightlifting for sports performance. J Strength Cond Res 37(6): 1163-1190, 2023-The origins of weightlifting and feats of strength span back to ancient Egypt, China, and Greece, with the introduction of weightlifting into the Olympic Games in 1896. However, it was not until the 1950s that training based on weightlifting was adopted by strength coaches working with team sports and athletics, with weightlifting research in peer-reviewed journals becoming prominent since the 1970s. Over the past few decades, researchers have focused on the use of weightlifting-based training to enhance performance in nonweightlifters because of the biomechanical similarities (e.g., rapid forceful extension of the hips, knees, and ankles) associated with the second pull phase of the clean and snatch, the drive/thrust phase of the jerk and athletic tasks such as jumping and sprinting. The highest force, rate of force development, and power outputs have been reported during such movements, highlighting the potential for such tasks to enhance these key physical qualities in athletes. In addition, the ability to manipulate barbell load across the extensive range of weightlifting exercises and their derivatives permits the strength and conditioning coach the opportunity to emphasize the development of strength-speed and speed-strength, as required for the individual athlete. As such, the results of numerous longitudinal studies and subsequent meta-analyses demonstrate the inclusion of weightlifting exercises into strength and conditioning programs results in greater improvements in force-production characteristics and performance in athletic tasks than general resistance training or plyometric training alone. However, it is essential that such exercises are appropriately programmed adopting a sequential approach across training blocks (including exercise variation, loads, and volumes) to ensure the desired adaptations, whereas strength and conditioning coaches emphasize appropriate technique and skill development of athletes performing such exercises.

Mechanical power production assessment during weightlifting exercises. A systematic review.

The assessment of the mechanical power production is of great importance for researchers and practitioners. The purpose of this review was to compare the differences in ground reaction force (GRF), kinematic, and combined (bar velocity x GRF) methods to assess mechanical power production during weightlifting exercises. A search of electronic databases was conducted to identify all publications up to 31 May 2019. The peak power output (PPO) was selected as the key variable. The exercises included in this review were clean variations, which includes the hang power clean (HPC), power clean (PC) and clean. A total of 26 articles met the inclusion criteria with 53.9% using the GRF, 38.5% combined, and 30.8% the kinematic method. Articles were evaluated and descriptively analysed to enable comparison between methods. The three methods have inherent methodological differences in the data analysis and measurement systems, which suggests that these methods should not be used interchangeably to assess PPO in Watts during weightlifting exercises. In addition, this review provides evidence and rationale for the use of the GRF to assess power production applied to the system mass while the kinematic method may be more appropriate when looking to assess only the power applied to the barbell.

Caffeine ingestion attenuates diurnal variation of lower-body ballistic performance in resistance-trained women.

ABSTRACTThe present study investigates the effect of an acute intake of caffeine on the diurnal variation of neuromuscular performance in resistance-trained women. A total of 15 resistance-trained women participated in the current triple-blind, placebo-controlled, crossover experimental study. We assessed neuromuscular performance (i.e. ballistic (countermovement jump [CMJ] height and bench press throw [BPT] peak velocity), maximal strength (squat and bench press [BP] one-repetition maximum [1RM]), and strength-endurance [average velocity of the set during squat and number of repetitions-to-failure in BP]) four times at within 7 days. The participants ingested an acute dose of caffeine (3 mg/kg) or a placebo at 9-11 am and/or 17-19 pm. CMJ height (P = .016) and BP peak velocity (P = .012) were higher in the afternoon than in the morning. Compared to placebo, caffeine intake increased CMJ height by 3.1% in the morning and 1.6% in the afternoon (P = .035), but it had no effect on BPT peak velocity (P = .381). Maximal strength and strength-endurance performances were not affected by the time-of-day or caffeine intake (all P > .3). No significant interaction (time-of-day x substance) was observed in any of the above-mentioned outcomes (all P > .1). In conclusion, an acute dose of caffeine in the morning was effective to restore CMJ performance to levels found in the afternoon, while this effect was not observed neither in BPTpeak velocity nor in lower- and upper-body maximal strength and strength-endurance performance. Moreover, lower- and upper-body ballistic performance were greater in the afternoon than in the morning in resistance-trained women, while the acute intake of caffeine was only effective to increase CMJ height.HighlightsBallistic performance is probably higher in the afternoon than in the morning in resistance-trained women.An acute intake of caffeine is effective to increase countermovement jump performance.The ingestion of an acute dose of caffeine in the morning restored countermovement jump performance to levels found in the afternoon.

How Does Lower-Body and Upper-Body Strength Relate to Maximum Split Jerk Performance?

ABSTRACT: Soriano, MA, Jiménez-Ormeño, E, Amaro-Gahete, FJ, Haff, GG, and Comfort, P. How does lower-body and upper-body strength relate to maximum split jerk performance? J Strength Cond Res 36(8): 2102-2107, 2022-The aims of this study were to (I) determine the relationships between the maximum dynamic strength of the upper and lower body, measured by overhead press and back squat 1 repetition maximum (1RM) performances, and the split jerk (SJ) performance in trained weightlifters and (II) explore the magnitude of these relationships for men and women to establish sex-specific prediction equations. Twenty men (age: 28.9 ± 6.6 years; height: 1.8 ± 0.1 m; body mass [BM]: 82.5 ± 10.2 kg; weightlifting training experience: 4.2 ± 2.4 years) and 13 women (age: 27.7 ± 4.4 years; height: 1.7 ± 0.1 m; BM: 61.8 ± 5.2 kg; weightlifting training experience: 2.7 ± 1.7 years) competitive weightlifters participated. The 1RM performances of the overhead press, back squat, and SJ were assessed for all subjects. A very strong correlation exists between the back squat and overhead press, with maximum SJ performance for all subjects (r = 0.97; p < 0.001). Similarly, very strong correlations were found for men (r = 0.90, p < 0.001) and women (r = 0.90, p = 0.0002), separately. The coefficient of determination indicates that the prediction equation for the maximum SJ performance is quite accurate (R2 = 0.94) for all subjects and men (R2 = 0.83) and women (R2 = 0.81), separately. These results provide evidence that the maximum strength of the upper and lower body are major contributors to SJ performance. In addition, SJ performance can accurately be predicted from the back squat and overhead press performances.

Does Sex Impact the Differences and Relationships in the One Repetition Maximum Performance Across Weightlifting Overhead Pressing Exercises?

ABSTRACT: Soriano, MA, García-Ramos, A, Calderbank, J, Marín, PJ, Sainz de Baranda, P, and Comfort, P. Does sex impact the differences and relationships in the one repetition maximum performance across weightlifting overhead pressing exercises? J Strength Cond 36(7): 1930-1935, 2022-This study aimed to determine the impact of sex on the differences and relationships of the one repetition maximum (1RM) performance between 3 overhead pressing exercises (push press [PP], push jerk [PJ] and split jerk [SJ]). 15 men (body mass [BM]: 82.3 ± 9.9 kg; weightlifting training experience: 2.6 ± 1.6 years) and 15 women (BM: 64.4 ± 7.0 kg; weightlifting training experience: 2.2 ± 1.4 years) participated in this study. A ratio-scaled (1RM·BM-1) was used for the comparison between them. The 1RM of the 3 exercises were evaluated within the same testing session using a combined 1RM assessment method. The interaction effect of exercise and sex did not reach statistical significance (p = 0.671; η2 = 0.001). In contrast, there were significant main effects of exercise (p ≤ 0.01) and sex (p < 0.001) with medium (η2 = 0.096) and large effect sizes (η2 = 0.306), respectively. A similar main effect of exercise was reported for both men (PP [1.0 ± 0.1 kg·kg-1] < PJ [1.1 ± 0.2 kg·kg-1] ∼ SJ [1.2 ± 0.2 kg·kg-1]) and women (PP [0.8 ± 0.1 kg·kg-1] < PJ [0.9 ± 0.2 kg·kg-1] ∼ SJ [0.9 ± 0.2 kg·kg-1]). The 1RM performance of the 3 exercises was significantly correlated for men (r [range] = 0.856-0.963) and women (r [range] = 0.636-0.925). Sex does not affect the differences in the 1RM performance across weightlifting overhead pressing exercises. However, stronger correlations and lower variation in the 1RM performance during the PP, PJ, and SJ are expected for men compared with women.

No differences in weightlifting overhead pressing exercises kinetics.

This study aimed to compare the kinetics between the push press (PP), push jerk (PJ), and split jerk (SJ). Sixteen resistance-trained participants (12 men and 4 women; age: 23.8 ± 4.4 years; height: 1.7 ± 0.1 m; body mass: 75.7 ± 13.0 kg; weightlifting experience: 2.2 ± 1.3 years; one repetition maximum [1RM] PP: 76.5 ± 19.5 kg) performed 3 repetitions each of the PP, PJ, and SJ at a relative load of 80% 1RM PP on a force platform. The kinetics (peak and mean force, peak and mean power, and impulse) of the PP, PJ, and SJ were determined during the dip and thrust phases. Dip and thrust displacement and duration were also calculated for the three lifts. In addition, the inter-repetition reliability of each variable across the three exercises was analysed. Moderate to excellent reliability was evident for the PP (Intraclass correlation coefficient [ICC] = 0.91-1.00), PJ (ICC = 0.86-1.00), and SJ (ICC = 0.55-0.99) kinetics. A one-way analysis of variance revealed no significant or meaningful differences (p > 0.05, η2 ≤ 0.010) for any kinetic measure between the PP, PJ, and SJ. In conclusion, there were no differences in kinetics between the PP, PJ, and SJ when performed at the same standardised load of 80% 1RM PP.

Validity and Reliability of a Standardized Protocol for Assessing the One Repetition Maximum Performance During Overhead Pressing Exercises.

ABSTRACT: Soriano, MA, García-Ramos, A, Torres-González, A, Castillo-Palencia, J, Ayuso, V, Marín, PJ, and Comfort, P. Validity and reliability of a standardized protocol for assessing the one repetition maximum performance during overhead pressing exercises. J Strength Cond Res 35(11): 2988-2992, 2021-The aim of this study was to determine the validity of performing 3 one repetition maximum (1RM) assessments for the push press (PP), push jerk (PJ), and split jerk (SJ) in sequence in one testing session vs. the criterion method (testing on separate days), while determining the between-session reliability of the combined assessment. Twenty-two well-trained men (n = 22; age: 28.5 + 1.3 years; height: 1.80 + 0.04 m; body mass: 84.9 + 1.9 kg; training experience: 4.27 + 4.08 years) participated in this study. The 1RM was assessed in a sequential order in the same testing session (combined 1RM assessment) for the PP, PJ, and SJ on 2 occasions, to determine between-session reliability. The 1RM for each exercise was also examined on 3 separate sessions to compare the results against the combined method. A high reliability, low variability, and low measurement error were evident for the PP (intraclass correlation coefficient [ICC] = 0.960; coefficient of variation [CV] = 1.8%; smallest detectable difference [SDD] = 7.1%), PJ (ICC = 0.978; CV = 1.5%; SDD = 5.4%) and SJ (ICC = 0.987; CV = 0.8%; SDD = 4.6%). In addition, there were no significant (p > 0.05) or meaningful (η2 ≤0.001) differences between the single and combined assessments. The high reliability and validity of the combined assessment suggest that practitioners and researchers may simplify the testing procedure by assessing the 1RM during the 3 main overhead pressing exercises in a single testing session.

Comparison of 1-Repetition-Maximum Performance Across 3 Weightlifting Overhead Pressing Exercises and Sport Groups.

OBJECTIVE: To (1) compare the 1-repetition-maximum (1RM) performance between the push press, push jerk, and split jerk and (2) explore these differences between weightlifters, CrossFit athletes, and a mixed group of athletes. METHODS: Forty-six resistance-trained males (age 28.8 [6.4] y; height 180.0 [6.0] cm; body mass 84.1 [10.2] kg; weightlifting training experience 3.64 [3.14] y) participated in this study. The 1RM performance of the push press, push jerk, and split jerk was assessed during the same session in a sequential order (ie, combined 1RM assessment method). Thirty-six participants were retested to determine between-sessions reliability of the 1RM values. RESULTS: Intraclass correlation coefficients (ICCs) and associated 95% confidence intervals (CIs) showed a high between-sessions reliability for the push press (ICC = .98; 95% CI, .95-.99), push jerk (ICC = .99; 95% CI, .98-1.00), and split jerk (ICC = .99; 95% CI, .98-1.00). There was a significant main effect of exercise (η2 = .101) and exercise × group interaction (η2 = .012) on 1RM performance (P < .001), whereas the main effect of group did not reach statistical significance (P = .175). CONCLUSIONS: This study provides evidence that the weightlifting overhead press derivatives affect 1RM performance. In addition, the interaction of exercise and sport group was caused by the higher differences in 1RM performance between exercises for weightlifters compared with CrossFit and a mixed group of athletes. Therefore, strength and conditioning professionals should be aware that the differences in 1RM performance between weightlifting overhead-press derivatives may be affected by sport group.

Weightlifting Overhead Pressing Derivatives: A Review of the Literature.

This review examines the literature on weightlifting overhead pressing derivatives (WOPDs) and provides information regarding historical, technical, kinetic and kinematic mechanisms as well as potential benefits and guidelines to implement the use of WOPDs as training tools for sports populations. Only 13 articles were found in a search of electronic databases, which was employed to gather empirical evidence to provide an insight into the kinetic and kinematic mechanisms underpinning WOPDs. Practitioners may implement WOPDs such as push press, push jerk or split jerk from the back as well as the front rack position to provide an adequate stimulus to improve not only weightlifting performance but also sports performance as: (1) the use of WOPDs is an additional strategy to improve weightlifting performance; (2) WOPDs require the ability to develop high forces rapidly by an impulsive triple extension of the hips, knees and ankles, which is mechanically similar to many sporting tasks; (3) WOPDs may be beneficial for enhancing power development and maximal strength in the sport population; and, finally, (4) WOPDs may provide a variation in training stimulus for the sports population due to the technical demands, need for balance and coordination. The potential benefits highlighted in the literature provide a justification for the implementation of WOPDs in sports training. However, there is a lack of information regarding the longitudinal training effects that may result from implementing WOPDs.