Portions of the force-velocity relationship targeted by weightlifting exercises

We compared the force-velocity (F-V) characteristics between jump squat (JS) and weightlifting (hang clean [HC] and HC pull [HCP]) to determine lower limb F-V portions targeted by weightlifting exercises. Ten weightlifters performed JS at 0% (body weight only) to 70% of their one-repetition maximum (1RM) for back squat, and HC and HCP at 30‒90% and 30‒110% of their 1RM for HC, respectively. Force and velocity values at each relative load were plotted to determine the F-V features of JS, HC, and HCP. Linear regression was used to evaluate each participant's JS F-V results to obtain individual F-V relationships. Regression equations evaluated the JS force at a given velocity for each relative load of HC and HCP. HC produced significantly less force than JS at given velocities for 30%, 40%, and 50% 1RM. Furthermore, HCP produced significantly less force than JS at a given velocity for 30% 1RM and exhibited less force than JS at a given velocity for 40% 1RM with moderate effect size. HC and HCP produce comparable forces to JS within the velocity ranges of 60‒90% and 50‒110% 1RM, respectively. Thus, weightlifting exercises target low‒moderate-velocity portion of the lower limb F-V relationship.

Effects of Training With Different Hang-Power-Clean Intensities on the Maximum Dynamic Strength, Vertical Jump, and Sprint Performance of Female Handball Players

PURPOSE

To compare the effects of 7 weeks of training with different hang-power-clean (HPC) intensities on the maximum dynamic strength, vertical jump, and sprint performance of female handball players.

METHODS

Professional handball athletes with at least 1 year of HPC experience volunteered to participate. The athletes were balanced by position and randomly assigned to a group with HPC at 90% (HPC90%) or 50% (HPC50%) of HPC 1-repetition maximum (1RM). The training volume was equalized between groups. Pretraining and posttraining assessments included 1RM HPC, jump height in the squat jump (SJ) and countermovement jump (CMJ), and sprint speeds at 5, 20, and 30 m.

RESULTS

From pretraining to posttraining, both groups significantly increased (P ≤ .05) 1RM HPC, although a small effect size was observed in favor of HPC90%. HPC90% and HPC50% did not induce significant changes (P > .05) in the SJ and CMJ height, although for the SJ, a small effect size was observed in favor of HPC90%. Both groups induced a significant improvement (P ≤ .05) in 5-, 20-, and 30-m sprint speeds, although for all speeds, small to moderate effect sizes were observed in favor of HPC90%.

CONCLUSIONS

Both training groups induced significant improvements in 1RM HPC and sprint speeds, whereas no significant changes were observed in vertical jumps. In addition, based mainly on the effect sizes, the HPC90% group was more effective for increasing 1RM HPC, SJ, and sprint speeds than the HPC50% group.

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.

Pairwise Comparison of Heavy Dynamic Strength and Fast Dynamic Strength Interventions on Sprint Performance: A Systematic Review and Meta-Analysis

ABSTRACT

Pairwise comparison of heavy dynamic strength and fast dynamic strength interventions on sprint performance: a systematic review and meta-analysis. J Strength Cond Res 38(9): 1675-1686, 2024-Previous studies have shown that both heavy dynamic strength (HDS) and fast dynamic strength (FDS) training can be used to improve sprint performance; however, a review and meta-analysis investigating pairwise studies that compare these two training interventions have not been performed. The aims of the study were to systematically review and analyze HDS and FDS training methodologies and evaluate their effect size difference, in pairwise comparison studies to determine and compare their effects on sprint performance. Databases were systematically searched using Boolean phrasing to identify eligible articles, and meta-analyses were performed on the extracted data. Seven studies met the inclusion criteria, which resulted in data from 138 subjects across 24 separate sprint assessments. Overall, there was a small effect in favor of FDS (standardized mean difference = 0.27, 95% confidence intervals [-0.07; 0.60], 95% prediction intervals [-1.01; 1.55]), but this was deemed not significant because of the wide-ranging prediction intervals. There is no distinguishable difference between HDS and FDS training on sprint performance. The wide-ranging prediction intervals suggest the variability is too great to determine whether one training type is more effective than the other. Practitioners should consider the individual needs of their athletes when deciding which training type to use for long-term sprint development.

Relationship between Countermovement Jump and Sprint Performance in Professional Football Players

Objectives: The aim of this study was to assess the relationship between the countermovement jump (CMJ) and sprint performance of professional football players, and to determine which strength and speed elements assessed by the CMJ translate into effective running. Methods: The research sample comprised 87 male professional football players (age 23.7 ± 4.20 years; body mass 82.33 ± 6.56 kg; body height 1.86 ± 0.05 m) who performed the CMJ on a dual-force platform, as well as the 30 m sprint test. The time and velocity of the run were recorded by photocells at 0, 5, 10, and 30 m of the distance. Results: No significant differences were noted in the time or velocity of the sprint over the initial 5 m between the groups of football players with a higher and lower braking rate of force development (RFD) in the CMJ (p > 0.05). However, at subsequent intervals (5-10 m and 10-30 m), players with a higher braking RFD achieved significantly better time and velocity than those with a lower RFD. Significant correlations in the group with a lower braking RFD between the CMJ and sprint variables occurred in the propulsion phase of the CMJ and most of them were in the first interval (0-5 m). In the group with a higher braking RFD, significant relationships were visible in both the propulsion (concentric) and braking (eccentric) phases of the CMJ, mainly during the second and third intervals of the sprint test. Conclusions: The noted observations may suggest that the relationship between strength and running performance is more complex than previously indicated, and that higher strength in the CMJ does not fully correlate with better sprinting. Therefore, it has been hypothesized that training aimed at generally increasing strength may not always be fully beneficial for running performance in football players and hence specific training guidelines are suggested for targeted strengthening of the required muscle performance characteristics. This may possibly contribute to reducing the unnecessary muscle overload during both training and matches, thereby preventing sports-related injuries.

Relative Strength and Physical Performance in US Army Male and Female Soldiers

ABSTRACT

Grier, T, Benedict, T, Mahlmann, O, and Canham-Chervak, M. Relative Strength and Physical Performance in U.S. Army Male and Female Soldiers. J Strength Cond Res 38(8): 1479-1485, 2024-In occupations with high physical demands, strength relative to bodymass is an important measure as it signifies an individual's ability to control and move their body mass through space. The purpose of this investigation was to examine physical characteristics, training, and performance based on different magnitudes of relative strength. Subjects were 1,806 male and 319 female US Army soldiers. Sex, age, height, body mass, and physical training data were obtained by an electronic survey. Physical performance was measured by the Army Combat Fitness Test (ACFT), which includes a three-repetition maximum deadlift, standing power throw, hand release push-up, sprint-drag-carry, leg tuck, and two-mile run. The relative body mass deadlifted was calculated and categorized into 4 groups for men and 3 groups for women. An analysis of variance and post hoc least significant difference test were used to evaluate the differences in relative strength and physical performance. Overall, 33% of men deadlifted ≥1.5 times their body mass, while 30% of women deadlifted ≥1.25 times their body mass. Men and women deadlifting the highest percentage of their body mass (≥1.5 times for men and ≥1.25 times for women) outperformed those with lower relative strength within their own sex in all 6 ACFT events. In 4 of the 6 ACFT events, women who deadlifted ≥1.25 times their body mass had similar performance compared with men deadlifting 1 to 1.24 times their body mass and outperformed men deadlifting <1 times their body mass. Greater strength relative to body mass was associated with higher physical performance.

Relationship between vertical jump performance and playing time and efficiency in professional male basketball players

With innovative force plate technology being available to many sports organizations worldwide that allow for time-efficient in-depth neuromuscular performance assessment, the purpose of the present study was to examine the relationship between some of the most commonly analyzed countermovement vertical jump (CVJ) force-time metrics and basketball playing time and efficiency. Twenty-four professional male basketball players volunteered to participate in the present study. The CVJ testing procedures were conducted within the first quarter of the competitive season span. Following a standardized warm-up protocol, each athlete stepped on a dual uni-axial force plate system sampling at 1,000 Hz and performed three maximum-effort CVJs with no arm swing. To minimize the possible influence of fatigue, each jump trial was separated by a 10-15 s rest interval and the average value across three jumps was used for performance analysis purposes. Basketball playing efficiency and average playing time were obtained at the end of the regular season competitive period from the coaching staff records and the official team records. Pearson product-moment correlation coefficients (r) were used to examine the strength of the relationships between force-time metrics and basketball playing time and efficiency, separately for each dependent variable (p < 0.05). A significant positive association was observed between playing efficiency and eccentric mean force and eccentric mean and peak power (r = 0.406-0.552). Similarly, an increase in eccentric mean power was positively correlated with the number of minutes played during the competitive season (r = 0.464). Moreover, the aforementioned relationship remained present even when eccentric mean power was expressed relative to the player's body mass (r = 0.406). Thus, the findings of the present study indicate that, at the professional level of men's basketball competition, CVJ eccentric strength and power have a positive impact on both playing time and efficiency.

Vertical jump neuromuscular performance of professional female handball players-starters vs. non-starters comparison

Given the complex nature of the handball as a game, players are required to possess a distinct set of physical and physiological attributes to attain peak performance. With the countermovement vertical jump (CVJ) being widely implemented as a non-invasive and time-efficient testing modality in sports settings, the purpose of the present study was twofold: (a) to establish a CVJ profile of professional female handball players and (b) to examine differences in force-time metrics between starters and non-starters. Forty-two professional female handball players (e.g., SuperLeague) volunteered to participate in this study. Each athlete performed three maximum-effort CVJs with no arm swing while standing on a uni-axial force plate system sampling at 1,000 Hz. Independent t-tests were used to examine differences in each variable between starters and non-starters. The results revealed that starters attained superior performance within the eccentric phase of the CVJ when compared to non-starters, particularly in terms of eccentric peak velocity (-0.957 ± 0.242 vs. -0.794 ± 0.177 m·s-1), eccentric mean power (320.0 ± 77.7 vs. 267.1 ± 75.2 W), and eccentric peak power (929.0 ± 388.1 vs. 684.4 ± 214.2 W). While not reaching the level of statistical significance, moderate-to-large effect sizes were observed for concentric impulse, peak velocity, and mean and peak force and power, all in favor of players included in the starting lineup (g = 0.439-0.655). Overall, these findings suggest that at the top-tier level of handball competition, the ability to secure a spot in a starting lineup may be possibly influenced by the athlete's eccentric performance capabilities. Thus, the development of lower-body eccentric strength and power may positively impact on-court athlete performance and ultimately help the team secure the desired game outcome.

The Effects of Holistic, External, and Internal Attentional Focus Instructions on Power and Kinematics of the Hang Power Snatch in Highly Skilled Weightlifters

Athletes across various sports seek to enhance their power generation and force production by incorporating weightlifting exercises into their training. Therefore, integrating partial weightlifting movements could be sensible due to their simplified execution. Our research aimed to investigate which of four attentional focus strategies (external, internal, holistic, and neutral) would have the greatest impact on performance in terms of power variables for highly experienced weightlifting athletes in a practical training setting. Twelve highly skilled Olympic weightlifters volunteered for the study. They performed 48 single repetitions of the hang power snatch with each of the four attentional focus strategies. Results of the ANOVA did not reveal a significant main effect for maximum velocity, power measurement and displacement. Despite extensive research demonstrating how attentional focus affects performance differently, even among highly skilled populations, the lack of observed effects in our study underscores the challenges of conducting research in applied settings.

Effects of Expertise on Muscle Activity during the Hang Power Clean and Hang Power Snatch Compared to Snatch and Clean Pulls - An Explorative Analysis

The purpose was to compare the electromyographic (EMG) activity of the Hang Power Clean (HPC) and Hang Power Snatch (HPS) with the Hang Clean Pull (HCP) and Hang Snatch Pull (HSP). Additionally, the influence of weightlifting expertise (beginner, advanced and elite) on EMG activity was analyzed. Twenty-seven weightlifters (beginner: n = 11, age: 23.9 ± 3.2 years, bodyweight: 75.7 ± 10.5 kg; advanced: n = 10, age: 24.8 ± 4.5 years, bodyweight: 69.4 ± 13.9 kg; elite: n = 6, age: 25.5 ± 5.2 years, bodyweight: 75.5 ± 12.5 kg) participated in this study. Participants performed two repetitions of HPC, HPS, HCP, and HSP at 50%, 70%, and 90% 1RM, respectively. The EMG activity of vastus lateralis (VL), gluteus maximus (GM), erector spinae (ES), rectus abdominis (RA) and trapezius (TZ) was recorded and normalized to the maximum voluntary isometric contraction (MVIC) of each muscle. There were significant differences in RA and ES EMG activity at 70% and 90% 1RM during HPC compared to HCP in the beginner group (p < 0.05, Hedges g = 0.50-1.06). Significant greater ES activity was observed in the beginner, advanced, and elite groups (p < 0.05, g = 0.27-0.98) during the HPS when compared to the HSP at 50-90% 1RM. TZ muscle activity was significantly greater at 50% and 70% 1RM in the HCP compared to the HPC in the elite group (p < 0.05, g = 0.61-1.08), while the beginner group reached significance only at 50% 1RM favoring HPC (p < 0.05, g = 0.38). Moreover, the EMG activity of the TZ during the HSP and HPS was significantly different only at 50% 1RM in the elite group and favored HSP (p < 0.05, g = 0.27). No differences were observed between the levels of weightlifting expertise. Based upon the results of this study, the overall pattern of EMG activity of the predominant muscles involved in HPC/HPS and the corresponding weightlifting pulling derivatives, apart from the stabilizing muscle (RA and ES), is similar at higher intensities (>70% 1RM) and expertise does not influence muscle activity.

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 XX(X): 000-000, 2022-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.

Maximal strength measurement: A critical evaluation of common methods-a narrative review

Measuring maximal strength (MSt) is a very common performance diagnoses, especially in elite and competitive sports. The most popular procedure in test batteries is to test the one repetition maximum (1RM). Since testing maximum dynamic strength is very time consuming, it often suggested to use isometric testing conditions instead. This suggestion is based on the assumption that the high Pearson correlation coefficients of r ≥ 0.7 between isometric and dynamic conditions indicate that both tests would provide similar measures of MSt. However, calculating r provides information about the relationship between two parameters, but does not provide any statement about the agreement or concordance of two testing procedures. Hence, to assess replaceability, the concordance correlation coefficient (ρ c) and the Bland-Altman analysis including the mean absolute error (MAE) and the mean absolute percentage error (MAPE) seem to be more appropriate. Therefore, an exemplary model based on r = 0.55 showed ρ c = 0.53, A MAE of 413.58 N and a MAPE = 23.6% with a range of -1,000-800 N within 95% Confidence interval (95%CI), while r = 0.7 and 0.92 showed ρ c = 0.68 with a MAE = 304.51N/MAPE = 17.4% with a range of -750 N-600 N within a 95% CI and ρ c = 0.9 with a MAE = 139.99/MAPE = 7.1% with a range of -200-450 N within a 95% CI, respectively. This model illustrates the limited validity of correlation coefficients to evaluate the replaceability of two testing procedures. Interpretation and classification of ρ c, MAE and MAPE seem to depend on expected changes of the measured parameter. A MAPE of about 17% between two testing procedures can be assumed to be intolerably high.

Influence of maximal strength performance in front squat and deadlift on linear sprint and jump performance in male youth elite basketball players

Background

Strength and speed are two major factors that determine performance in basketball players especially sprinting, jumping and change of direction. This study examined relationships of maximal strength in the front squat and the deadlift with basketball-specific sprint and jump performance tests that are commonly used in test batteries of athletic diagnostics.

Materials and methods

In all, 42 youth male elite basketball players (age: 14.7 ± 2.4 years, age range: 13–18 years, height: 179.1 ± 15.3 cm, weight: 69.8 ± 19.2 kg) volunteered to take part in the present study. The one repetition maximum (1 RM) in the front squat and deadlift were used to determine maximum strength. Countermovement jump (CMJ) and standing long jump were evaluated to determine jump performance and 5, 10, and 20 m linear sprint as well as agility T‑test were performed to determine sprint performance. Pearson correlation analysis was used to assess the relationships between strength and jump and sprint performance.

Results

Strong positive correlations were found between maximal strength and jump heights (r = 0.85–0.91, p < 0.001) and strong negative correlations were determined between maximal strength and measured sprint times r = (−0.71 to −0.85, p < 0.001).

Conclusion

The measured maximal strength in the front squat and deadlift seem to be good predictors for basketball-specific jump and sprint performance. From this, it seems to be beneficial to include training of maximal strength via front squat and deadlift into training routines as well as performance diagnostics.

Comparison of Joint-Level Kinetics During Single-Leg and Double-Leg Weightlifting Derivatives

ABSTRACT

Hayashi, R, Yoshida, T, and Kariyama, Y. Comparison of joint-level kinetics during single- and double-leg weightlifting derivatives. J Strength Cond Res XX(X): 000-000, 2022-Humans have different 3-dimensional biomechanical characteristics of the lower extremities during locomotion with one and both legs. These biomechanical characteristics may also be observed in the weightlifting derivatives. This study aimed to compare the 3-dimensional joint kinetics of the lower extremities during the single-leg hang power clean (SHPC) and double-leg hang power clean (DHPC). Ten male track and field athletes performed the SHPC and DHPC using external loads of 30, 60, and 90% of one repetition maximum (1RM). The 1RMs in SHPC and DHPC were measured separately, and the external loads at 30, 60, and 90% of the 1RM used were determined based on the different 1RMs in SHPC and DHPC. We calculated the joint moment and joint power of the SHPC and DHPC using a motion capture system and force platforms. The hip abduction moment and power of the SHPC were significantly greater than those of the DHPC under all external loads (p < 0.05). In addition, ankle joint moment at all external loads and joint power at 90% of 1RM was greater for SHPC than for DHPC (p < 0.05). Furthermore, although hip (extension-flexion) and ankle joint kinetics in SHPC and DHPC showed similar load dependence, hip abduction axis kinetics was not load dependent. These results suggest that the hip (abduction-adduction) and ankle joint kinetics in SHPC are greater than in DHPC, but hip (abduction-abduction) kinetics in SHPC is not load independent.

Effects of Different Levels of Weightlifting Training on Bone Mineral Density in a Group of Adolescents

The aim of the current study was to evaluate the effects of different levels of weightlifting training on bone mineral density (BMD) at different body sites (whole body (WB), lumbar spine (LS), femoral neck (FN), upper limbs (UL) and lower limbs (LL)) in a group of adolescents. Three groups of pubertal boys aged 13-15 years were recruited, including a control group (which included 13 untrained adolescents), a moderately trained group (which included 13 non-elite weightlifters, with four sessions of 2 hours per week) and a highly trained group (which included 13 elite weightlifters, with eight sessions of 2 hours per week). The three groups were paired for age and maturation index (using Tanner stages). Body composition, bone mineral content (BMC) and BMD were evaluated by dual-energy X ray absorptiometry (DXA). Physical performance variables (including weightlifting specific exercises, counter movement jump and squat jump) were measured using validated methods. Results showed that the values of BMD and physical performance variables were greater in the group of elite weightlifters compared to the group of non-elite weightlifters and the control group. In addition, the values of BMD and physical performance variables were higher in the group of the non-elite weightlifters compared to those of the control group. After adjusting for lean mass and squat jump, lumbar spine BMD, FN BMD, UL BMD and LL BMD remained significantly higher in the elite weightlifters' group compared to the two other groups. In conclusion, the current study suggests that elite adolescent weightlifters have greater bone health parameters compared to moderately-trained adolescent weightlifters and untrained adolescents.

Associations between lower limb eccentric muscle capability and change of direction speed in basketball and tennis players

Background

The ability to perform a quick and rapid change of direction (CoD) is an important determinant of success in a variety of sports. Previous studies have already highlighted that eccentric strength is a dominant predictor of CoD. However, these studies evaluated eccentric strength through a limited number of outcome measures and used small sample sizes.

Methods

A total of 196 athletes participated in the study. The aim of our study was to investigate: (1) the correlation between eccentric outcome measures derived from different tests (Nordic hamstring exercise (NHE), countermovement jump (CMJ) and flywheel (FW) squats), (2) the association between eccentric outcome measures and CoD 90°, CoD 180°; and (3) proportion of explained variance in CoD performance.

Results

Very large associations (r = 0.783, p < 0.001) were observed between peak torque during NHE (NHE_PT) and force impulse during the eccentric phase of CMJ (CMJ_FI). Small to moderate correlations were calculated between peak eccentric force in flywheel squats and peak eccentric force in CMJ (r = 0.220-035, p < 0002). All eccentric CMJ outcome measures and NHE_PT were reported as moderate negative associations with both CoD tests. Eccentric measures explained 25.1% of the variance in CoD 90° (CMJ_PF, NHE_PT, F_0.125 -peak eccentric force during FW squats with 0.125 kg m² load), while the same outcome measures explained 37.4% of the variance for CoD 180°.

Conclusion

Our results suggest that different measures of eccentric strength specifically contribute to CoD performance. Therefore, for successful CoD performance, different aspects of eccentric strength training should be considered in testing and training (maximal eccentric strength, eccentric-concentric actions with fast execution).

Comparison of Weightlifting, Traditional Resistance Training and Plyometrics on Strength, Power and Speed: A Systematic Review with Meta-Analysis

Background

Weightlifting training (WLT) is commonly used to improve strength, power and speed in athletes. However, to date, WLT studies have either not compared training effects against those of other training methods, or been limited by small sample sizes, which are issues that can be resolved by pooling studies in a meta-analysis. Therefore, the objective of this systematic review with meta-analysis was to evaluate the effects of WLT compared with traditional resistance training (TRT), plyometric training (PLYO) and/or control (CON) on strength, power and speed.

Methods

The systematic review included peer-reviewed articles that employed a WLT intervention, a comparison group (i.e. TRT, PLYO, CON), and a measure of strength, power and/or speed. Means and standard deviations of outcomes were converted to Hedges’ g effect sizes using an inverse variance random-effects model to generate a weighted mean effect size (ES).

Results

Sixteen studies were included in the analysis, comprising 427 participants. Data indicated that when compared with TRT, WLT resulted in greater improvements in weightlifting load lifted (4 studies, p = 0.02, g = 1.35; 95% CI 0.20–2.51) and countermovement jump (CMJ) height (9 studies, p = 0.00, g = 0.95; 95% CI 0.04–1.87). There was also a large effect in terms of linear sprint speed (4 studies, p = 0.13, g = 1.04; 95% CI − 0.03 to 2.39) and change of direction speed (CODS) (2 studies, p = 0.36, g = 1.21; 95% CI − 1.41 to 3.83); however, this was not significant. Interpretation of these findings should acknowledge the high heterogeneity across the included studies and potential risk of bias. WLT and PLYO resulted in similar improvements in speed, power and strength as demonstrated by negligible to moderate, non-significant effects in favour of WLT for improvements in linear sprint speed (4 studies, p = 0.35, g = 0.20; 95% CI − 0.23 to 0.63), CODS (3 studies, p = 0.52, g = 0.17; 95% CI − 0.35 to 0.68), CMJ (6 studies, p = 0.09, g = 0.31; 95% CI − 0.05 to 0.67), squat jump performance (5 studies, p = 0.08, g = 0.34; 95% CI − 0.04 to 0.73) and strength (4 studies, p = 0.20, g = 0.69; 95% CI − 0.37 to 1.75).

Conclusion

Overall, these findings support the notion that if the training goal is to improve strength, power and speed, supplementary weightlifting training may be advantageous for athletic development. Whilst WLT and PLYO may result in similar improvements, WLT can elicit additional benefits above that of TRT, resulting in greater improvements in weightlifting and jumping performance.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40279-021-01627-2.

Olympic Sports Science-Bibliometric Analysis of All Summer and Winter Olympic Sports Research

Introduction: The body of scientific literature on sports and exercise continues to expand. The summer and winter Olympic games will be held over a 7-month period in 2021-2022. Objectives: We took this rare opportunity to quantify and analyze the main bibliometric parameters (i.e., the number of articles and citations) across all Olympic sports to weigh and compare their importance and to assess the structure of the "sport sciences" field. The present review aims to perform a bibliometric analysis of Olympic sports research. We quantified the following topics: (1) the most investigated sports; (2) the main journals in which the studies are published; (3) the main factors explaining sport-specific scientific attractiveness; (4) the influence of being in the Olympic programme, economic weight, and local influences on research output; and (5) which research topic is the most investigated across sports. Methods: We searched 116 sport/exercise journals on PubMed for the 40 summer and 10 winter Olympic sports. A total of 34,038 articles were filtered for a final selection of 25,003 articles (23,334 articles on summer sports and 1,669 on winter sports) and a total of 599,820 citations. Results and Discussion: Nine sports [football (soccer), cycling, athletics, swimming, distance & marathon running, basketball, baseball, tennis, and rowing] were involved in 69% of the articles and 75% of the citations. Football was the most cited sport, with 19.7 and 26.3% of the total number of articles and citations, respectively. All sports yielded some scientific output, but 11 sports (biathlon, mountain biking, archery, diving, trampoline, skateboarding, skeleton, modern pentathlon, luge, bobsleigh, and curling) accumulated a total of fewer than 50 publications. While ice hockey is the most prominently represented winter sport in the scientific literature, winter sports overall have produced minor scientific output. Further analyses show a large scientific literature on team sports, particularly American professional sports (i.e., baseball, basketball, and ice hockey) and the importance of inclusion in the Olympic programme to increasing scientific interest in "recent" sports (i.e., triathlon and rugby sevens). We also found local/cultural influence on the occurrence of a sport in a particular "sport sciences" journal. Finally, the relative distribution of six main research topics (i.e., physiology, performance, training and testing, injuries and medicine, biomechanics, and psychology) was large across sports and reflected the specific performance factors of each sport.

The Differentiate Effects of Resistance Training With or Without External Load on Young Soccer Players' Performance and Body Composition

Purpose: The purpose of this study was to examine the effects of 15 weeks (2/week) of two different resistance training (RT) programs [the self-load group (SG) vs. the overload group (OG)] on selected measures of physical performance in young male soccer players. Methods: The countermovement jump (CMJ), aerobic endurance (VO2 max), and body composition [body mass (BM), height (H), body fat percentage (% BF), and lean mass (LM)] were measured before and after the 15-week RT interventions. Subjects were randomized to treatments: 1. SG [age = 15.34 ± 1.34 years]; 2. OG [age = 16.28 ± 1.21 years]. Results: The level of significance set for the study (p ≤ 0.05). Within-group analysis did report significant differences in all variables for the SG (p = 0.008 to 0.001; ES = -0.33 to 1.41, small to large) as in the OG (p = 0.001; ES = 0.82 to 1.30, large). Between-groups analysis reported differences in CMJ (F = 4.32; p = 0.004) for the OG. Conclusion: The main findings of this study indicated that RT with and without external load was effective in improving the measures of physical performance in young soccer players, with special attention to jumping ability, where the OG group was more effective. Furthermore, there is no interference to aerobic endurance. It is recommended that soccer coaches implement RT without external load in the early stages of training or in players with late maturation development and in those soccer clubs with limited material resources.

Comparing Biomechanical Time Series Data During the Hang-Power Clean and Jump Shrug

ABSTRACT

Kipp, K, Comfort, P, and Suchomel, TJ. Comparing biomechanical time series data during the hang-power clean and jump shrug. J Strength Cond Res 35(9): 2389-2396, 2021-The purpose of this study was to investigate differences in the force-, velocity-, displacement-, and power-time curves during the hang-power clean (HPC) and the jump shrug (JS). To this end, 15 male lacrosse players were recruited from a National Collegiate Athletic Association Division-I team, and performed one set of 3 repetitions of the HPC and JS at 70% of their HPC 1 repetition maximum (1RM HPC). Two in-ground force plates were used to measure the vertical ground reaction force (GRF) and calculate the barbell-lifter system mechanics during each exercise. The time series data were normalized to 100% of the movement phase, which included the initial countermovement and extension phases, and analyzed with curve analysis and statistical parametric mapping (SPM). The SPM procedure highlighted significant differences in the force-time curves of the HPC and JS between 85 and 100% of the movement phase. Likewise, the SPM procedure highlighted significant differences in the velocity- and power-time curve of the HPC and JS between 90 and 100% of the movement phase. For all comparisons, performance of the JS was associated with greater magnitudes of the mechanical outputs. Although results from the curve analysis showed significant differences during other periods of the movement phase, these differences likely reflect statistical issues related to the inappropriate analysis of time series data. Nonetheless, these results collectively indicate that when compared with the HPC, execution of the JS is characterized by greater GRF and barbell-lifter system velocity and power outputs during the final 10% of the movement phase.

Effects of Sex and Age on Physical Testing Performance for Law Enforcement Agency Candidates: Implications for Academy Training

ABSTRACT

Bloodgood, AM, Dawes, JJ, Orr, RM, Stierli, M, Cesario, KA, Moreno, MR, Dulla, JM, and Lockie, RG. Effects of sex and age on physical testing performance for law enforcement agency candidates: implications for academy training. J Strength Cond Res 35(9): 2629-2635, 2021-Law enforcement candidates are often required to complete fitness tests to assess their preparedness for training. This study investigated the influence of sex and age on candidate performance before academy training. Retrospective analysis of 516 candidates was performed. Data were stratified into men (n = 432) and women (n = 84), and the pooled (men and women combined) data were stratified into age groups (20-24; 24-29; 30-34; 35-39; and 40+ years). The tests included the following: maximal push-ups and sit-ups in 60 seconds; a 75-yard pursuit run (75PR); arm ergometer revolutions completed in 60 seconds; and a 2.4-km run. To compare the sex and age groups, a 2 × 5 analysis of variance (with Bonferroni post hoc for multiple between-age group comparisons) was used. Men performed significantly (p < 0.001) more push-ups, sit-ups, and arm ergometer revolutions and were faster in the 75PR and 2.4-km run. The 20-24, 25-29, and 35-39 year groups were faster in the 75PR compared with the 40+ year group; the 20-24 and 25-29 year groups were faster than the 35-39 year group; and the 20-24 year group was faster than the 30-34 year group (p ≤ 0.023). The 20-24 year group was faster than the 40+ year group in the 2.4-km run (p = 0.005). Women and older candidates may have a lower physical capacity than men and younger candidates, respectively, in certain physical assessments. Women and older candidates, in particular, may benefit from dedicated training before academy to better prepare for the demands of this period.

Analysis of Record Scores in the Clean and Its Variations in the Long-Term Training of Young Weightlifters

ABSTRACT

Szyszka, P and Czaplicki, A. Analysis of record scores in the clean and its variations in the long-term training of young weightlifters. J Strength Cond Res 35(9): 2383-2388, 2021-The main objectives of this study were to determine the time trajectories of record scores in the clean lift (C) and its derivatives achieved by young weightlifters in a 2-year training cycle and to estimate the quantitative relationships between these scores. The study involved 17 weightlifters who were tested 7 times at 3-month intervals. The computations were based on an individual growth curve approach. The study found statistically significant increases (p < 0.05) in record scores between consecutive measurements until the last measurement for the hang clean (HC), the second to last measurement for the C, and the fourth measurement for the power clean (PC) and the hang power clean (HPC). The overall mean ratios of the record scores in the C to those in the HC, PC, and HPC were approximately constant and amounted to 0.96, 0.89, and 0.80, respectively. Statistically significant differences (p < 0.05) between individual time trajectories of record scores in the C and its derivatives were also identified in the 2 consecutive annual training macrocycles. The results suggest that the long-term analysis of record scores in the C and its derivatives can be useful in assessing athletes' sport level, in predicting their performance, and in proper exercise selection in the training of young weightlifters.

Performance Comparisons of Youth Weightlifters as a Function of Age Group and Sex

This study was designed to provide an overview of weightlifting performance as a function of age group and sex and evaluate the potential of countermovement jump height (CMJH) as a tool to gauge performance potential. Data from 130 youth athletes (female, n = 65 & male, n = 65) were used to examine progression of performance (Total and Sinclair total) and the relationship between CMJH and Sinclair total while considering interactions between CMJH and age and/or sex. ANOVAs with post hoc analyses revealed that both totals had a statistical first-order polynomial interaction effect between age group and sex and the difference between age groups of 12-13 and 14-15 years old was statistically greater for male than female. A linear model, developed to examine the relationship, revealed that CMJH and CMJH x sex x age rejected the null hypothesis. Our primary findings are that male youth weightlifters have a higher rate of performance progression, possibly owing to puberty, and CMJH may be a better gauging tool for older male youth weightlifters.

Differences in body composition and physical fitness of Korean national bobsleigh and skeleton athletes

BACKGROUND

This study aimed to classify Olympic medalists and non-medalists among national bobsled and skeleton athletes and determine the physical fitness differences between the two groups.

METHODS

Five bobsleigh and skeleton athletes who won gold and silver medals in the 2018 Pyeongchang Winter Olympics and 11 national bobsled and skeleton team athletes were recruited. The participants were assessed for physiological parameters such as body composition, anthropometry, physical fitness, isokinetic strength, and maximum strength.

RESULTS

Physical fitness factors back strength (t=2.571, p<0.05), squat ability (t=3.061, p<0.01), and left and right leg curls (t=4.578, p<0.001; t=4.719, p<0.001, respectively) were significantly different between the groups. The original value of the primary discriminant analysis was 1.868 and the canonical correlation was 0.807. The average value of the discriminant function of the medalists was 1.896, while the of the non-medalists was -0.862, indicating that the two groups were completely different.

CONCLUSIONS

Medalists have higher squat abilities, abdominal strength, and leg curl strength than nonmedalists, particular with regard to hamstring strength. Currently, in most sports events, athletes undergo physical training to improve performance; however, training programs that reflect the characteristics of the sport and the physical characteristics of excellent athletes are still insufficient.

Differences in Kinetics during One- and Two-Leg Hang Power Clean

The purpose of this study was to quantify the kinetics per leg during the one- and two-leg hang power clean using various loads. Nine male track and field athletes performed the one- and two-leg hang power clean on a force platform. The estimated one-repetition maximum was used for the one-leg hang power clean (OHPC), and the one-repetition maximum was used for the two-leg hang power clean (THPC). The loads used were 30%, 60%, and 90% during both trials. We calculated peak power, peak force, and peak rate of force development during the pull phase from the force-time data. The peak power and the peak force for all loads during the OHPC were statistically greater than during the THPC. The peak rates of force development at 60% and 90% during the OHPC were statistically greater than during the THPC. Additionally, the peak power at 90% was significantly less than at 60% during the THPC. These findings suggest that the OHPC at loads of 60% and 90% is a weightlifting exercise that exhibits greater explosive force and power development characteristics than the THPC.

Jump Training in Rugby Union Players: Barbell or Hexagonal Bar?

ABSTRACT

Weakley, JJS, Till, K, Read, DB, Leduc, C, Roe, GAB, Phibbs, PJ, Darrall-Jones, J, and Jones, B. Jump training in rugby union players: barbell or hexagonal bar?. J Strength Cond Res 35(3): 754-761, 2021-The countermovement jump (CMJ) is an exercise that can develop athletic performance. Using the conventional barbell (BAR) and hexagonal barbell (HEX) while jumping, the intensity can be increased. However, the bar that provides greater adaptations is unknown. Therefore, this study aimed to assess changes in loaded and unloaded CMJ with either a BAR or HEX across a 4-week mesocycle in rugby union players. Twenty-nine subjects were strength-matched and randomized into 2 groups. Subjects completed 3 sets of CMJ at 20% of 1 repetition maximum back squat, 3 times per week for 4 weeks, using either a BAR or HEX. Subjects completed an unloaded CMJ on a force plate before and after, whereas the highest peak concentric velocity during the jump squat was recorded in the first and last training sessions using a linear position transducer. Magnitude-based inferences assessed meaningful changes within- and between-groups. Possibly greater improvements in unloaded CMJ were found in the HEX group in jump height (effect size ± 90% confidence intervals: 0.27 ± 0.27), relative peak (0.21 ± 0.23), and mean power (0.32 ± 0.36). In addition, likely to very likely greater improvements were observed in the HEX group in peak velocity (0.33 ± 0.27), relative mean power (0.53 ± 0.30), mean force (0.47 ± 0.27), and 100-ms impulse (0.60 ± 0.48). Similar raw changes in jump squat peak velocity occurred (0.20-0.25 m·s-1), despite the likely greater ES occurring with the BAR (0.32 ± 0.26). These results indicate that training with the HEX leads to superior unloaded CMJ adaptations. In addition, practitioners should use either the HEX or BAR when aiming to enhance loaded jump ability.

Ergogenic effects of lifting straps on movement velocity, grip strength, perceived exertion and grip security during the deadlift exercise

It is possible that during resistance training, a weak link in the kinetic chain could possibly result in under-stimulated prime movers. Since grip strength can be a limiting factor during multiple sets of various pulling exercises such as deadlifts, it is important to determine how lifting straps can affect mechanical performance, grip strength, perceived exertion and perceived grip security and power. Sixteen males (24.4 ± 2.3 y; 181.6 ± 5.8 cm; 86.6 ± 8.2 kg) completed three protocols: 4 sets of 4 repetitions without straps using 80% of their without-straps 1-repetition max (DLnn); the same protocol with straps based on their without-straps 1-repetition max (DLwn); and the same with straps based on their with-straps 1-repetitions max (DLww). DLwn allowed for greater mean velocity (MV) and peak velocity (PV) than DLnn and DLww, while MV and PV were greater during DLnn than DLww. The magnitude of grip fatigue was lower during DLwn and DLww than DLn. Perceived grip security and power were greater during DLwn and DLww compared to DLn. Perceived exertion was lower during DLwn than DLnn and DLww. These findings suggest that the use of lifting straps during deadlifts allows for a better maintenance of grip strength, faster grip strength recovery following training, and greater perceived grip security and power than deadlifts performed without lifting straps, while also increasing mechanical performance and decreasing the perceived exertion. Therefore, the ergogenic potential of the lifting straps has important training implications and should be considered during RT involving the deadlift exercise and possibly other pulling exercises.

Physiology of Basketball - Field Tests. Review Article

The game of basketball is characterized by short and intense bouts of activity at medium to high frequency. Basketball entails specific types of movements, physiological requirements and energy sources. The duration of physiological responses involving ATP, CP and glycolysis responses to this type of activity is 5-6 seconds for a single sprint, and a contribution of the aerobic system is of less than 10%. Recovery periods in basketball, as a rule, are not long enough to fill the gap for such high intensity activities. It is hard to achieve the same level of performance consistently over time in repeated sprints. This means that basketball players need great athletic ability in order to demonstrate speed, strength and power required to produce a successful performance most proficiently. Therefore, tests are needed to help coaches to monitor their players and ensure that they have the physiological capacity required for the game. The aim of fitness tests is to assess the condition of athletes in terms of each fitness component, in order to determine what needs to be improved through the training program and to conduct retests at set times to assess whether their condition has changed. The literature offers a number of widely used tests to measure aerobic and anaerobic fitness. This article reviews the physiological demands of basketball and analyzes the field tests commonly used at present. The article emphasizes the need for a specific test that will serve coaches and physical fitness trainers in monitoring their players.

A Comparison of Kinetic and Kinematic Variables During the Pull From the Knee and Hang Pull, Across Loads

Meechan, D, McMahon, JJ, Suchomel, TJ, and Comfort, P. A comparison of kinetic and kinematic variables during the pull from the knee and hang pull, across loads. J Strength Cond Res 34(7): 1819-1829, 2020-Kinetic and kinematic variables during the pull from the knee (PFK) and hang pull (HP) were compared in this study. Eighteen men (age = 29.43 ± 3.95 years; height 1.77 ± 0.08 m; body mass 84.65 ± 18.79 kg) performed the PFK and HP with 40, 60, 80, 100, 120, and 140% of 1-repetition maximum (1RM) power clean, in a progressive manner. Peak force (PF), mean force (MF), peak system velocity (PSV), mean system velocity (MSV), peak power (PP), mean power (MP), and net impulse were calculated from force-time data during the propulsion phase. During the HP, small-to-moderate yet significantly greater MF was observed compared with the PFK, across all loads (p ≤ 0.001; Hedges g = 0.47-0.73). Hang pull PSV was moderately and significantly greater at 100-140% 1RM (p = 0.001; g = 0.64-0.94), whereas MSV was significantly greater and of a large-to-very large magnitude compared with PFK, across all loads (p < 0.001; g = 1.36-2.18). Hang pull exhibited small to moderate and significantly greater (p ≤ 0.011, g = 0.44-0.78) PP at 100-140%, with moderately and significantly greater (p ≤ 0.001, g = 0.64-0.98) MP across all loads, compared with the PFK. Hang pull resulted in a small to moderate and significantly greater net impulse between 100 and 140% 1RM (p = 0.001, g = 0.36-0.66), compared with PFK. The results of this study demonstrate that compared with the PFK, the HP may be a more beneficial exercise to enhance force-time characteristics, especially at loads of ≥1RM.

Training With Weightlifting Derivatives: The Effects of Force and Velocity Overload Stimuli

Suchomel, TJ, McKeever, SM, and Comfort, P. Training with weightlifting derivatives: The effects of force and velocity overload stimuli. J Strength Cond Res 34(7): 1808-1818, 2020-The purposes of this study were to compare the training effects of weightlifting movements performed with (CATCH) or without (PULL) the catch phase of clean derivatives performed at the same relative loads or training without the catch phase using a force- and velocity-specific overload stimulus (OL) on isometric and dynamic performance tasks. Twenty-seven resistance-trained men completed 10 weeks of training as part of the CATCH, PULL, or OL group. The CATCH group trained using weightlifting catching derivatives, while the PULL and OL groups used biomechanically similar pulling derivatives. The CATCH and PULL groups were prescribed the same relative loads, while the OL group was prescribed force- and velocity-specific loading that was exercise and phase specific. Preintervention and postintervention isometric midthigh pull (IMTP), relative one repetition maximum power clean (1RM PC), 10-, 20-, and 30-m sprint, and 505 change of direction on the right (505R) and left (505L) leg were examined. Statistically significant differences in preintervention to postintervention percent change were present for relative IMTP peak force, 10-, 20-, and 30-m sprints, and 505L (all p < 0.03), but not for relative 1RM PC or 505R (p > 0.05). The OL group produced the greatest improvements in each of the examined characteristics compared with the CATCH and PULL groups with generally moderate to large practical effects being present. Using a force- and velocity-specific overload stimulus with weightlifting pulling derivatives may produce superior adaptations in relative strength, sprint speed, and change of direction compared with submaximally loaded weightlifting catching and pulling derivatives.

Association of strength and plyometric exercises with change of direction performances

The change of direction (COD) ability is an important task-specific skill for success in team sports, dependent on both strength and reactive strength. The sprint approaching the COD and degrees of the turn are factors influencing the specificity of the COD. Thus, CODs have been suggested to be categorized as force- (> 90°) and velocity-dominant (< 90°) dependent on the degree of the turn. When training programmes fail to provide a significant increase in COD performance, it is often due to neglecting the task-specific demands of the COD. As such, 23 male football players volunteered to complete a randomized controlled trial, investigating the association of maximal strength and power performance with performance in a force- (180°) and velocity-dominant (45°) COD, with a 4 m and 20 m sprint approach. Three strength and three plyometric exercises, matched in movement patterns, were used. Muscle activity of the different conditions was also compared. The correlational analysis revealed that better performance in the plyometric tests were associated with less time to complete both force- and velocity-dominant CODs, supported by similarities in muscle activation. None of the performances in strength exercises correlated to COD performance, due to the slow contraction velocity of maximal lifts. It was concluded that plyometrics share more physical similarities with CODs than the strength exercises.

Effects of 10 months of Speed, Functional, and Traditional Strength Training on Strength, Linear Sprint, Change of Direction, and Jump Performance in Trained Adolescent Soccer Players

Keiner, M, Kadlubowski, B, Sander, A, Hartmann, H, and Wirth, K. Effects of 10 months of speed, functional, and traditional strength training on strength, linear sprint, change of direction, and jump performance in trained adolescent soccer players. J Strength Cond Res XX(X): 000-000, 2020-The current study aimed to compare the effects of plyometric and sprint vs. functional vs. strength training on linear sprint (LS 20 m), change of direction (COD; i.e., turning right and left), jump (squat jump [SJ]), and maximum strength (1 repetition maximum [1RM] for a squat) performance in elite adolescent soccer players. A longitudinal design was chosen, and 48 elite male youth were recruited. The athletes were divided into 4 groups (a traditional strength training group [STG], a plyometric and sprint training group [PSTG], a functional training group [FTG], and a control group [CG]). The intervention groups trained for 10 months with additional sessions added to their regular soccer training (4-5 sessions per week); the additional training (2 sessions a week [each about 60 minutes]) consisted of plyometric and sprint training, functional training, and traditional strength training for the PSTG, FTG, and STG, respectively. Data were analyzed using analysis of variance with repeated measurements. The effect sizes were calculated using Hedges g. This study showed significantly superior performance increases with traditional strength training compared with sprint and jump training and functional training for maximum strength (compared with all other groups g = 0.98-1.61), SJ (g = 0.52-0.87 compared with FGT and CG; not significantly different from PSTG), COD (direction of rotation right: compared with all other groups g = 1.58-2.12; direction of rotation left: no significant differences), and 20-m LS (compared with all other groups g = 0.86-1.39) performance over time. Traditional strength training is recommended to increase strength and speed-strength variables and should therefore be given high priority in athletic training programs for elite youth soccer players.

The Relationship between Isometric Force-Time Characteristics and Dynamic Performance: A Systematic Review

The purpose of this article was to review the data on the relationship between multi-joint isometric strength test (IsoTest) force-time characteristics (peak force, rate of force development and impulse) and dynamic performance that is available in the current literature. Four electronic databases were searched using search terms related to IsoTest. Studies were considered eligible if they were original research studies that investigated the relationships between multi-joint IsoTest and performance of dynamic movements; published in peer-reviewed journals; had participants who were athletes or active individuals who participate in recreational sports or resistance training, with no restriction on sex; and had full text available. A total of 47 studies were selected. These studies showed significant small to large correlations between isometric bench press (IBP) force-time variables and upper body dynamic performances (r² = 0.221 to 0.608, p < 0.05) and significant small to very large correlation between isometric squat (ISqT) (r² = 0.085 to 0.746, p < 0.05) and isometric mid-thigh pull (IMTP) (r² = 0.120 to 0.941, p < 0.05) force-time variables with lower body dynamic performances. IsoTest force-time characteristics were shown to have small to very large correlations with dynamic performances of the upper and lower limbs as well as performance of sporting movements (r² = 0.118 to 0.700, p < 0.05). These data suggest that IsoTest force-time characteristics provide insights into the force production capability of athletes which give insight into dynamic performance capabilities.

The Effect of Training with Weightlifting Catching or Pulling Derivatives on Squat Jump and Countermovement Jump Force-Time Adaptations

The purpose of this study was to examine the changes in squat jump (SJ) and countermovement jump (CMJ) force-time curve characteristics following 10 weeks of training with either load-matched weightlifting catching (CATCH) or pulling derivatives (PULL) or pulling derivatives that included force- and velocity-specific loading (OL). Twenty-five resistance-trained men were randomly assigned to the CATCH, PULL, or OL groups. Participants completed a 10 week, group-specific training program. SJ and CMJ height, propulsion mean force, and propulsion time were compared at baseline and after 3, 7, and 10 weeks. In addition, time-normalized SJ and CMJ force-time curves were compared between baseline and after 10 weeks. No between-group differences were present for any of the examined variables, and only trivial to small changes existed within each group. The greatest improvements in SJ and CMJ height were produced by the OL and PULL groups, respectively, while only trivial changes were present for the CATCH group. These changes were underpinned by greater propulsion forces and reduced propulsion times. The OL group displayed significantly greater relative force during the SJ and CMJ compared to the PULL and CATCH groups, respectively. Training with weightlifting pulling derivatives may produce greater vertical jump adaptations compared to training with catching derivatives.

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.

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.

Evaluation of Strength and Conditioning Measures With Game Success in Division I Collegiate Volleyball: A Retrospective Study

Bunn, JA, Ryan, GA, Button, GR, and, and Zhang, S. Evaluation of strength and conditioning measures with game success in Division I collegiate volleyball: A retrospective study. J Strength Cond Res 34(1): 183-191, 2020-The purpose of this study was to retrospectively assess relationships between strength and conditioning (SC) measures and game performance in Division I volleyball. Five years of SC and game data were collected from 1 women's Division I collegiate team, n = 76. Strength and conditioning measures included T-drill, 18.3 m sprint, back squat, hang clean, vertical jump, and broad jump. All game and SC stats were normalized to Z-scores. Analyses included assessing SC differences by position and multiple stepwise regression to assess relationships between game and SC stats. There was a significant difference by position for broad jump (p = 0.002), 18.3 m sprint (p = 0.036), vertical (p ≤ 0.001), and total strength (p = 0.019). Overall, game performance and SC measures were significantly correlated (r = 0.439, p ≤ 0.001). Multiple regression analyses indicated significant relationships (p ≤ 0.05) between SC measures and game success by position as follows: defensive specialist stats with squat and total strength; setters game stats with hang cleans, T-drill, and broad jump; pin hitter game stats with vertical, squat, and total strength; middle blockers game stats with broad jump. These data indicate that SC measures correlate well with game performance and are specific by position. These data could help SC coaches create a more precise training approach to focus on improving specific measures by position, which could then translate to improved game performance. These data could also help coaches with talent identification to determine playing time and rotations to maximize player ability and achieve success.

Angular Velocity, Moment, and Power Analysis of the Ankle, Knee, and Hip Joints in the Goalkeeper's Diving Save in Football

The aim of this study was to identify biomechanical characteristics of goalkeeper's diving performance in football. Lower extremity joints powers, moments, and angular velocities, were investigated in seven elite goalkeepers diving to save balls, shot from a ball canon to unanticipated heights (high and low) and sides (right and left). Our result showed that there was a proximal-to-distal sequence for each leg in timing of peak joints powers (p < 0.05). Hip extensors produced the largest (p < 0.05) peak moment, the contralateral (relative to dive side) peak was significantly larger than the ipsilateral one for high (4.56 ± 1.02 N·m·kg-1, and 3.52 ± 0.79 N·m·kg-1) and low dives (3.52 ± 0.79 N·m·kg-1, and 2.52 ± 0.56 N·m·kg-1). The ankle plantar flexors produced the second largest peak moment (p < 0.05), and the peak ipsilateral ankle power and angular velocity were the largest (p < 0.05) of all joints, during high (1,502 ± 338 W, and 14.73 ± 1.36 rad·s-1) and low dives (868 ± 263 W, and 14.14 ± 3.09 rad·s-1). Strength and conditioning coaches need to focus on hip extensors and ankle plantar flexors, and for specificity in power training that should elicit triple extension of the lower limbs' joints in a proximal-to-distal sequence.

Is the Optimal Load for Maximal Power Output During Hang Power Cleans Submaximal?

PURPOSE

The optimal load for maximal power output during hang power cleans (HPCs) from a mechanical perspective is the 1-repetition-maximum (1RM) load; however, previous research has reported otherwise. The present study thus aimed to investigate the underlying factors that determine optimal load during HPCs.

METHODS

Eight competitive Olympic weight lifters performed HPCs at 40%, 60%, 70%, 80%, 90%, 95%, and 100% of their 1RM while the ground-reaction force and bar/body kinematics were simultaneously recorded. The success criterion during HPC was set above parallel squat at the receiving position.

RESULTS

Both peak power and relative peak power were maximized at 80% 1RM (3975.7 [439.1] W, 50.4 [6.6] W/kg, respectively). Peak force, force at peak power, and relative values tended to increase with heavier loads (P < .001), while peak system velocity and system velocity at peak power decreased significantly above 80% 1RM (P = .005 and .011, respectively). There were also significant decreases in peak bar velocity (P < .001) and bar displacement (P < .001) toward heavier loads. There was a strong positive correlation between peak bar velocity and bar displacement in 7 of 8 subjects (r > .90, P < .01). The knee joint angle at the receiving position fell below the quarter-squat position above 70% 1RM.

CONCLUSIONS

Submaximal loads were indeed optimal for maximal power output for HPC when the success criterion was set above the parallel-squat position. However, when the success criterion was defined as the quarter-squat position, the optimal load became the 1RM load.

The Effects of Augmented Feedback on Sprint, Jump, and Strength Adaptations in Rugby Union Players After a 4-Week Training Program

PURPOSE

Feedback can enhance acute physical performance. However, its effects on physical adaptation have received little attention. Therefore, the purpose of this study was to determine the effect of feedback during a 4-wk training program on jump, sprint, and strength adaptations.

METHODS

A total of 28 semiprofessional male rugby union players were strength-matched into 2 groups (feedback and nonfeedback). During the 4-wk training program, the Feedback group received immediate, objective feedback on (1) mean concentric velocity during resistance training repetitions, (2) distance feedback for standing broad jumps, and (3) time for sprints. The Nonfeedback group was not provided additional information. Across the 4-wk mesocycle, subjects completed 3 strength and conditioning sessions per week. Countermovement jump, standing long jump, 10- and 20-m sprint, and 3-repetition-maximum barbell back squat and bench press were measured before and after the training intervention. Magnitude-based inferences assessed meaningful changes within and between groups.

RESULTS

The Feedback group showed small to moderate improvements in outcome measures, whereas the Nonfeedback group demonstrated trivial to small improvements. Improvements in countermovement-jump relative peak power (effect size ± 90% confidence limits: 0.34 ± 0.42), 10-m (0.20 ± 0.35) and 20-m sprints (0.40 ± 0.21), and 3-repetition-maximum back squats (0.23 ± 0.17) were possibly to likely greater for the Feedback condition than for Nonfeedback.

CONCLUSIONS

Providing augmented feedback during strength and conditioning routines can enhance training adaptations compared with athletes who do not receive feedback. Consequently, practitioners should consider providing kinematic outputs, displacement, or sprint time at the completion of each repetition as athletes train.

Effects of Low-Moderate Load High-Velocity Resistance Training on Physical Performance of Under-20 Futsal Players

Resistance training (RT) is an effective methodology to improve physical performance of athletes. However, up to now, no studies have addressed the RT benefits in under-20 futsal players. The purpose of this study was to evaluate the effects of six weeks of RT with high-velocity movements, low-to-moderate loads, and low volume on physical performance of under-20 futsal players. A total of 21 players were divided into two groups: A control group (CG, n = 10) and a RT group (RTG, n = 11). The RTG performed two weekly training sessions constituted by leg-press, jumps, and sprints, along with three futsal training sessions, while the CG only performed the futsal training. Before and after the intervention, the sprint time in 0⁻10 m (T10), 10⁻20 m (T10⁻20), and 0⁻20 m (T20), the countermovement jump (CMJ) height, the T-Test time, the kicking ball speed (KBS), and the maximum dynamic strength in the leg-press, were assessed. In post-test, significant improvements in CMJ, T-Test, KBS, and leg-press were found for the RTG, whilst a significant decrease in T10⁻20 was evidenced in the CG. The present results suggested that RT based on high velocity movements, low-to-moderate loads, and low volume produce positive effects on physical performance of under-20 futsal players.

An Investigation Into the Effects of Excluding the Catch Phase of the Power Clean on Force-Time Characteristics During Isometric and Dynamic Tasks: An Intervention Study

Comfort, P, Dos'Santos, T, Thomas, C, McMahon, JJ, and Suchomel, TJ. An investigation into the effects of excluding the catch phase of the power clean on force-time characteristics during isometric and dynamic tasks: an intervention study. J Strength Cond Res 32(8): 2116-2129, 2018-The aims of this study were to compare the effects of the exclusion or inclusion of the catch phase during power clean (PC) derivatives on force-time characteristics during isometric and dynamic tasks, after two 4-week mesocycles of resistance training. Two strength matched groups completed the twice-weekly training sessions either including the catch phase of the PC derivatives (Catch group: n = 16; age 19.3 ± 2.1 years; height 1.79 ± 0.08 m; body mass 71.14 ± 11.79 kg; PC 1 repetition maximum [1RM] 0.93 ± 0.15 kg·kg) or excluding the catch phase (Pull group: n = 18; age 19.8 ± 2.5 years; height 1.73 ± 0.10 m; body mass 66.43 ± 10.13 kg; PC 1RM 0.91 ± 0.18 kg·kg). The Catch and Pull groups both demonstrated significant (p ≤ 0.007, power ≥0.834) and meaningful improvements in countermovement jump height (10.8 ± 12.3%, 5.2 ± 9.2%), isometric mid-thigh pull performance (force [F]100: 14.9 ± 17.2%, 15.5 ± 16.0%, F150: 16.0 ± 17.6%, 16.2 ± 18.4%, F200: 15.8 ± 17.6%, 17.9 ± 18.3%, F250: 10.0 ± 16.1%,10.9 ± 14.4%, peak force: 13.7 ± 18.7%, 9.7 ± 16.3%), and PC 1RM (9.5 ± 6.2%, 8.4 ± 6.1%), before and after intervention, respectively. In contrast to the hypotheses, there were no meaningful or significant differences in the percentage change for any variables between groups. This study clearly demonstrates that neither the inclusion nor exclusion of the catch phase of the PC derivatives results in any preferential adaptations over two 4-week, in-season strength and power, mesocycles.

Relationships between Unilateral Muscle Strength Qualities and Change of Direction in Adolescent Team-Sport Athletes

Previous studies have reported an association between global measures of bilateral strength and change of direction (COD) ability. Yet, little is known about the association between unilateral muscle strength qualities and COD ability. The aim of this study was to explore the associations between unilateral muscle strength qualities and COD measures (COD speed (CODS) and COD deficit) when matched limb-for-limb (i.e., right limb vs. right limb, left limb vs. left limb) in adolescent team-sport athletes. One hundred and fifteen athletes (56 males, 59 females) active in cricket, netball, and basketball participated in this investigation. Each player performed trials of countermovement jump (CMJ), single-leg hop (SLH), isometric mid-thigh pull (IMTP) and eccentric knee extensor torque (ECC-EXT) to assess muscle strength qualities and 505 and modified 505 (505mod) to evaluate COD ability. Moderate-to-large correlations were observed between SLH and CODS (r = -0.43 to -0.67). Another important finding was that CMJ measures demonstrated moderate-to-large correlations with CODS (r = -0.38 to -0.69) and small-to-moderate correlations with COD deficit (r = -0.24 to -0.45). COD is underpinned by distinct muscle strength qualities and each contribute to specific phases of a COD task. It is therefore likely that such connections exist between muscle strength qualities and COD, with all qualities contributing to overall COD ability.

Force-Time Differences between Ballistic and Non-Ballistic Half-Squats

The purpose of this study was to examine the force-time differences between concentric-only half-squats (COHS) performed with ballistic (BAL) or non-ballistic (NBAL) intent across a range of loads. Eighteen resistance-trained men performed either BAL or NBAL COHS at 30%, 50%, 70%, and 90% of their one repetition maximum (1RM) COHS. Relative peak force (PF) and relative impulse from 0–50 ms (Imp50), 0–90 ms (Imp90), 0–200 ms (Imp200), and 0–250 ms (Imp250) were compared using a series of 2 × 4 (intent × load) repeated measures ANOVAs with Bonferroni post hoc tests. Cohen’s d effect sizes were calculated to provide measures of practical significance between the BAL and NBAL COHS and each load. BAL COHS produced statistically greater PF than NBAL COHS at 30% (d = 3.37), 50% (d = 2.88), 70% (d = 2.29), and 90% 1RM (d = 1.19) (all p < 0.001). Statistically significant main effect differences were found between load-averaged BAL and NBAL COHS for Imp90 (p = 0.006, d = 0.25), Imp200 (p = 0.001, d = 0.36), and Imp250 (p < 0.001, d = 0.41), but not for Imp50 (p = 0.018, d = 0.21). Considering the greater PF and impulse observed during the BAL condition, performing COHS with BAL intent may provide a favorable training stimulus compared to COHS performed with NBAL intent.

Mechanical Demands of the Hang Power Clean and Jump Shrug: A Joint-Level Perspective

Kipp, K, Malloy, PJ, Smith, J, Giordanelli, MD, Kiely, MT, Geiser, CF, and Suchomel, TJ. Mechanical demands of the hang power clean and jump shrug: a joint-level perspective. J Strength Cond Res 32(2): 466-474, 2018-The purpose of this study was to investigate the joint- and load-dependent changes in the mechanical demands of the lower extremity joints during the hang power clean (HPC) and the jump shrug (JS). Fifteen male lacrosse players were recruited from a National Collegiate Athletic Association DI team, and completed 3 sets of the HPC and JS at 30, 50, and 70% of their HPC 1 repetition maximum (1RM HPC) in a counterbalanced and randomized order. Motion analysis and force plate technology were used to calculate the positive work, propulsive phase duration, and peak concentric power at the hip, knee, and ankle joints. Separate 3-way analysis of variances were used to determine the interaction and main effects of joint, load, and lift type on the 3 dependent variables. The results indicated that the mechanics during the HPC and JS exhibit joint-, load-, and lift-dependent behavior. When averaged across joints, the positive work during both lifts increased progressively with external load, but was greater during the JS at 30 and 50% of 1RM HPC than during the HPC. The JS was also characterized by greater hip and knee work when averaged across loads. The joint-averaged propulsive phase duration was lower at 30% than at 50 and 70% of 1RM HPC for both lifts. Furthermore, the load-averaged propulsive phase duration was greater for the hip than the knee and ankle joint. The joint-averaged peak concentric power was the greatest at 70% of 1RM for the HPC and at 30%-50% of 1RM for the JS. In addition, the joint-averaged peak concentric power of the JS was greater than that of the HPC. Furthermore, the load-averaged peak knee and ankle concentric joint powers were greater during the execution of the JS than the HPC. However, the load-averaged power of all joints differed only during the HPC, but was similar between the hip and knee joints for the JS. Collectively, these results indicate that compared with the HPC the JS is characterized by greater hip and knee positive joint work, and greater knee and ankle peak concentric joint power, especially if performed at 30 and 50% of 1RM HPC. This study provides important novel information about the mechanical demands of 2 commonly used exercises and should be considered in the design of resistance training programs that aim to improve the explosiveness of the lower extremity joints.