Most common movements preceding goal scoring situations in female professional soccer

This study aimed to assess movements occurring during goal scoring situations in a female professional league.Data from all the goals on the Women's Super League 2018/2019 were collected through time-motion analysis using a modified version of the Bloomfield Movement Classification with differences analysed through chi-square. Analysis was performed on players (assistant, scorer [attackers], defender of assistant and defender of scorer [defenders]), movements, intensities and directions.Linear advancing motion (walking, jogging, running or sprint) (total percentage [95% CI] 37% attackers and 32.7% defenders) was the most common action preceding a goal, followed by deceleration (21.5% attackers; 18.4% defenders) and turn (19.2% attackers; 17.6% defenders). Other movements involved but with lower percentages were change in angle run (cut and arc run), ball blocking, lateral advancing motion (crossover and shuffle) and jumps. Players displayed similar tendencies but presented variations based on the role, with attackers performing more linear actions, subtle turns and cuts and defenders more ball blocking actions, lateral movements and high intensity linear actions and decelerations. Assistant performed the less percentage of involvements with at least 1 high intensity action (67.4%), scorer and defender of assistant showed similar values (86.3% and 87.1%), while defender of scorer had the highest percentage (97.3%).This study shows the importance of linear actions with other movements also being of high significance but with differentiated characteristics based on the role. This study could help practitioners design drills for the enhancement of physical capabilities related to movements occurring in goal scoring situations.

Kinetic and Kinematic Characteristics Underpinning Change of Direction Performance in Basketball: A Comparative Study Between Sexes and Tests

ABSTRACT

Baena-Raya, A, Díez-Fernández, DM, Martínez-Rubio, C, Conceição, F, and López-Sagarra, A. Kinetic and kinematic characteristics underpinning change of direction performance in basketball: A comparative study between sexes and tests. J Strength Cond Res 38(4): e182-e188, 2024-This study (a) evaluated the sex-specific kinetic and kinematic outcomes underpinning change of direction (COD) performance, (b) compared these outcomes across 3 different COD tests, and (c) examined the sex-specific and test-specific outcome most strongly related to COD performance in basketball players. Thirty young basketball players (17 males and 13 females) competing at the national level were assessed for the modified 505 test, modified T test, and V-cut test. The Local Positioning System technology (WIMU PRO, Realtrack Systems S.L., Almería, Spain) was used to measure the maximum values of acceleration (ACC max ), deceleration (DEC max ), velocity (VEL max ), and centripetal force (CentF max ) in each COD test. Male players displayed greater ACC max , VEL max , DEC max , and CentF max outputs for each section of the 505 test, T test, and V-cut test (all p < 0.05), resulting in a faster COD performance than females across tests (all ES > -1.42; 95% CI = -3.45 to -0.57). The 505 test demanded significantly greater kinematic outputs than T test and V-cut test for both sexes ( p < 0.01). The ACC max explained ∼26-58% of the variability in COD time for males across tests ( p < 0.05) and 40% in females' modified 505-test time ( p < 0.05). Likewise, in females, DEC max explained 38% of the modified T -test time variability, whereas VEL max explained 53% in the V-cut test time (both p < 0.05). These findings suggest that (a) COD data should not be used interchangeably across sexes, (b) test specificities should be considered for designing COD training, and (c) the kinematic outcomes explaining COD performance might vary across sexes.

A Systematic Review and Meta-Analysis of Wearable Satellite System Technology for Linear Sprint Profiling: Technological Innovations and Practical Applications

ABSTRACT

Cormier, P, Meylan, C, Agar-Newman, D, Geneau, D, Epp-Stobbe, A, Lenetsky, S, and Klimstra, M. A systematic review and meta-analysis of wearable satellite system technology for linear sprint profiling: technological innovations and practical applications. J Strength Cond Res 38(2): 405-418, 2024-An emerging and promising practice is the use of global navigation satellite system (GNSS) technology to profile team-sports athletes in training and competition. Therefore, the purpose of this narrative systematic review with meta-analysis was to evaluate the literature regarding satellite system sensor usage for sprint modeling and to consolidate the findings to evaluate its validity and reliability. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, an electronic search of the databases, PubMed and SPORTDiscus (EBSCO), was conducted. Concurrent validity and reliability studies were considered, and 16 studies were retained for the review from the initial 1,485 studies identified. The effects on outcomes were expressed as standardized mean differences (SMDs, Cohen's d ) for each outcome (i.e., maximal sprint speed [MSS], the acceleration constant [τ], maximal theoretical velocity [ V0 ], relative force [ F0 ], and relative power [P max ]). Effect magnitudes represented the SMD between GNSS-derived and criterion-derived (i.e., radar and laser) and resulted in the following estimates: small for MSS ( d = 0.22, 95% CI 0.01 to 0.42), τ ( d = -0.18, 95% CI -0.60 to 0.23), V0 ( d = 0.14, 95% CI -0.08 to 0.36), relative F0 ( d = 0.15, 95% CI -0.25 to 0.55), and relative P max ( d = 0.21, 95% CI -0.16 to 0.58). No publication bias was identified in meta-analyzed studies and moderator analysis revealed that several factors (sampling rate and sensor manufacturer) influenced the results. Heterogeneity between studies was considered moderate to high. This highlighted the differences between studies in sensor technology differences (i.e., sampling rate, sensor fusion, and satellite network acquisition), processing techniques, criterion technology used, sprint protocols, outcome reporting, and athlete characteristics. These findings may be useful in guiding improvements in sprint modeling using GNSS technology and enable more direct comparisons in future research. Implementation of all-out linear sprint efforts with GNSS technology can be integrated into sport-specific sessions for sprint modeling when robust and consistent data processing protocols are performed, which has important implications for fatigue monitoring, program design, systematic testing, and rehabilitation in individual and team sports.

Performance Implications of Force-Vector-Specific Resistance and Plyometric Training: A Systematic Review with Meta-Analysis

BACKGROUND

According to the principle of specific adaptations to imposed demands, training induces specific adaptations that predominantly transfer towards performance tasks of similar physiological and/or biomechanical characteristics. Functional performance improvements secondary to resistance and plyometric training have been hypothesized to be force-vector specific; however, the literature pertaining to this matter appears somewhat equivocal.

OBJECTIVE

The objective of the present systematic review with meta-analysis was to synthesize the available body of literature regarding the performance implications of vertically and horizontally oriented resistance- and plyometric training.

DATA SOURCES

The review drew from the following sources: PubMed, Web of Science, Scopus, Physiotherapy Evidence Database (PEDro), Cochrane Library, Cumulative Index of Nursing and Allied Health Literature (CINAHL), SPORTDiscus and Google Scholar.

STUDY ELIGIBILITY CRITERIA

To qualify for inclusion, studies had to compare the efficacy of vertically and horizontally oriented resistance and/or plyometric training, with one or multiple outcome measures related to vertical/horizontal jumping, sprinting and/or change of direction speed (CODS).

STUDY APPRAISAL AND SYNTHESIS

For each outcome measure, an inverse-variance random effects model was applied, with between-treatment effects quantified by the standardized mean difference (SMD) and associated 95% confidence- and prediction intervals.

RESULTS

Between-treatment effects were of trivial magnitude for vertical jumping (SMD =  - 0.04, P = 0.69) and long-distance (≥ 20 m) sprinting (0.03, P = 0.83), whereas small to moderate effects in favor of horizontal training were observed for horizontal jumping (0.25, P = 0.07), short-distance (≤ 10 m) sprinting (0.72, P = 0.01) and CODS (0.31, P = 0.06), although only the short-distance sprint outcome reached statistical significance.

CONCLUSIONS

In conclusion, our meta-analysis reveals a potential superiority of horizontally oriented training for horizontal jumping, short-distance sprinting and CODS, whereas vertically oriented training is equally efficacious for vertical jumping and long-distance sprinting. From an applied perspective, the present analysis provides an advanced basis for weighting of vertical and horizontal force-vector exercises as an integrated component for optimizing sport-specific performances. The present systematic review with meta-analysis was not a priori registered.

Effects of combined plyometric, strength and running technique training program on change-of-direction and countermovement jump: A two-armed parallel study design on young soccer players

CONTEXT AND OBJECTIVE

Players must be capable to have a good change-of-direction (COD) skill aiming to be the fastest as possible to react immediately to the opponent or even to help players to be more agile since COD is a physical determinant of agility. Thus, the aim of this study was to test the effects of a six-week combined training intervention in the COD and countermovement jump (CMJ) of young soccer players, while comparing with a control group only performing the regular field-based training sessions.

METHODS

A sample of 80 non-professional players (40 experimental group and 40 control group) between the ages of ten and twelve was taken [(Age: 10.70 ± 1.02)]. The tests that were carried out from the beginning to the end of the intervention were: CMJ test, 505COD Test and Illinois Test. Paired sample t-test was used for determining differences as a repeated measures analysis (pre- post). An ANCOVA test was performed using the pretest as a covariate and the times pre and post as factors.

RESULTS AND CONCLUSIONS

Repeated measures ANCOVA revealed significant influence of baseline level on the 5-0-5 COD (p = 0.001; ηp2=0.170), the Illinois (p = 0.018; ηp2=0.070) and the CMJ (p = 0.047; ηp2=0.050). Significant interactions group*time (p < 0.001; ηp2=0.137), 5-0-5 COD (p < 0.001; ηp2=0.274), and CMJ (p < 0.001; ηp2=0.392) were found, while no significant interactions were found in Illinois (p = 0.293; ηp2=0.014). The current research revealed that a combined training intervention consisting of strength training, plyometrics, and running techniques can be significantly beneficial for improving COD performance and CMJ.

Sprint acceleration characteristics across the Australian football participation pathway

The aim of this study was to compare the force, velocity and power profiles of a maximal sprint acceleration through different competition levels of the Australian Football (AF) participation pathway. One hundred and sixty-two junior AF athletes across five competition levels including State under 18's (ST 18), State under 16's (ST 16), local under 18's (LOC 18), local under 15's (LOC 15), and local under 14's (LOC 14) participated in this cross-sectional study. Velocity-time data from maximal sprint accelerations were analysed to derive athlete's sprint acceleration characteristics and split times. ST 18 showed a more force-orientated profile than the LOC 18 with moderate differences in relative theoretical maximal force (F0) (7.54%), absolute F0 (10.51%), and slope of the force-velocity relationship (Sf-v) (9.27%). Similarly, small differences were found between ST 18 and ST 16 in relative F0 (4.79%) and Sf-v (6.28%). Moderate to extremely large differences were observed between players competing in older (ST 18, LOC 18, ST 16) compared to younger (LOC 15, LOC 14) competition levels highlighting the potential influence of biological maturation. It is recommended that practitioners working with junior AF players to consider developing a force-orientated sprint acceleration profile to improve sprinting performance.

Wheelchair Rugby Sprint Force-Velocity Modeling Using Inertial Measurement Units and Sport Specific Parameters: A Proof of Concept

BACKGROUND

Para-sports such as wheelchair rugby have seen increased use of inertial measurement units (IMU) to measure wheelchair mobility. The accessibility and accuracy of IMUs have enabled the quantification of many wheelchair metrics and the ability to further advance analyses such as force-velocity (FV) profiling. However, the FV modeling approach has not been refined to include wheelchair specific parameters.

PURPOSE

The purpose of this study was to compare wheelchair rugby sprint FV profiles, developed from a wheel-mounted IMU, using current mono-exponential modeling techniques against a dynamic resistive force model with wheelchair specific resistance coefficients.

METHODS

Eighteen athletes from a national wheelchair rugby program performed 2 × 45 m all-out sprints on an indoor hardwood court surface.

RESULTS

Velocity modelling displayed high agreeability, with an average RMSE of 0.235 ± 0.07 m/s-1 and r2 of 0.946 ± 0.02. Further, the wheelchair specific resistive force model resulted in greater force and power outcomes, better aligning with previously collected measures.

CONCLUSIONS

The present study highlights the proof of concept that a wheel-mounted IMU combined with wheelchair-specific FV modelling provided estimates of force and power that better account for the resistive forces encountered by wheelchair rugby athletes.

The Effect of a Heavy Resisted Sled-Pull Mesocycle on Sprint Performance in Junior Australian Football Players

ABSTRACT

Edwards, T, Piggott, B, Banyard, HG, Haff, GG, and Joyce, C. The effect of a heavy resisted sled-pull mesocycle on sprint performance in junior Australian football players. J Strength Cond Res 37(2): 388-393, 2023-This study assessed the effect of heavy resisted sled-pull training on sprint times and force, velocity, and power characteristics in junior Australian football players. Twenty-six athletes completed a 6-week resisted sled-pull training intervention which included 10 training sessions and 1-week taper. Instantaneous velocity during 2 maximal 30 m sprints was recorded 1 week before and 1 week after the intervention with a radar gun. Velocity-time data were used to derive sprint performance and force, velocity, and power characteristics. A paired t -test assessed the within-group differences between preintervention and postintervention testing. Statistical significance was accepted at p ≤ 0.05. Hedges' g effect sizes (ESs) were used to determine the magnitude of change in dependent variables. Maximum velocity (ES = 1.33) and sprint times at all distances (ES range 0.80-1.41) significantly improved after heavy resisted sled-pull training. This was reflected in sprint force, velocity, and power characteristics with significant improvements in relative theoretical force (ES = 0.63), theoretical velocity (ES = 0.99), relative maximum power (ES = 1.04), and ratio of horizontal to vertical force (ES = 0.99). Despite the multifactorial nature of training and competing physical demands associated with preseason training, these findings imply that a short, resisted sled-pull training mesocycle may improve sprint performance and underlying force, velocity, and power characteristics in junior athletes.

Exploratory Analysis of Sprint Force-Velocity Characteristics, Kinematics and Performance across a Periodized Training Year: A Case Study of Two National Level Sprint Athletes

Objective: This case study aimed to explore changes to sprint force-velocity characteristics across a periodized training year (45 weeks) and the influence on sprint kinematics and performance in national level 100-meter athletes. Force-velocity characteristics have been shown to differentiate between performance levels in sprint athletes, yet limited information exists describing how characteristics change across a season and impact sprint performance, therefore warranting further research. Methods: Two male national level 100-meter athletes (Athlete 1: 22 years, 1.83 m, 81.1 kg, 100 m time: 10.47 s; Athlete 2: 19 years, 1.82 cm, 75.3 kg, 100 m time: 10.81 s) completed 12 and 11 force-velocity assessments, respectively, using electronic timing gates. Sprint mechanical characteristics were derived from 30-meter maximal sprint efforts using split times (i.e., 0-10 m, 0-20 m, 0-30 m) whereas step kinematics were established from 100-meter competition performance using video analysis. Results: Between the preparation (PREP) and competition (COMP) phase, Athlete 1 showed significantly large within-athlete effects for relative maximal power (P_MAX), theoretical maximal velocity (v₀), maximum ratio of force (RF_MAX), maximal velocity (V_MAX), and split time from 0 to 20 m and 0 to 30 m (-1.70 ≤ ES ≥ 1.92, p ≤ 0.05). Athlete 2 reported significant differences with large effects for relative maximal force (F₀) and RF_MAX only (ES: ≤ -1.46, p ≤ 0.04). In the PREP phase, both athletes reported almost perfect correlations between F₀, P_MAX and 0-20 m (r = -0.99, p ≤ 0.01), however in the COMP phase, the relationships between mechanical characteristics and split times were more individual. Competition performance in the 100-meter sprint (10.64 ± 0.24 s) showed a greater reliance on step length (r ≥ -0.72, p ≤ 0.001) than step frequency to achieve faster performances. The minimal detectable change (%) across mechanical variables ranged from 1.3 to 10.0% while spatio-temporal variables were much lower, from 0.94 to 1.48%, with Athlete 1 showing a higher 'true change' in performance across the season compared to Athlete 2. Conclusions: The estimated sprint force-velocity data collected across a training year may provide insight to practitioners about the underpinning mechanical characteristics which affect sprint performance during specific phases of training, plus how a periodized training design may enhance sprint force-velocity characteristics and performance outcomes.

A novel guideline for the analysis of linear acceleration mechanics - outlining a conceptual framework of 'shin roll' motion

Linear acceleration is a key performance determinant and major training component of many sports. Although extensive research about lower limb kinetics and kinematics is available, consistent definitions of distinctive key body positions, the underlying mechanisms and their related movement strategies are lacking. The aim of this 'Method and Theoretical Perspective' article is to introduce a conceptual framework which classifies the sagittal plane 'shin roll' motion during accelerated sprinting. By emphasising the importance of the shin segment's orientation in space, four distinctive key positions are presented ('shin block', 'touchdown', 'heel lock' and 'propulsion pose'), which are linked by a progressive 'shin roll' motion during swing-stance transition. The shin's downward tilt is driven by three different movement strategies ('shin alignment', 'horizontal ankle rocker' and 'shin drop'). The tilt's optimal amount and timing will contribute to a mechanically efficient acceleration via timely staggered proximal-to-distal power output. Empirical data obtained from athletes of different performance levels and sporting backgrounds are required to verify the feasibility of this concept. The framework presented here should facilitate future biomechanical analyses and may enable coaches and practitioners to develop specific training programs and feedback strategies to provide athletes with a more efficient acceleration technique.

Biomechanical and Neuromuscular Performance Requirements of Horizontal Deceleration: A Review with Implications for Random Intermittent Multi-Directional Sports

Rapid horizontal accelerations and decelerations are crucial events enabling the changes of velocity and direction integral to sports involving random intermittent multi-directional movements. However, relative to horizontal acceleration, there have been considerably fewer scientific investigations into the biomechanical and neuromuscular demands of horizontal deceleration and the qualities underpinning horizontal deceleration performance. Accordingly, the aims of this review article are to: (1) conduct an evidence-based review of the biomechanical demands of horizontal deceleration and (2) identify biomechanical and neuromuscular performance determinants of horizontal deceleration, with the aim of outlining relevant performance implications for random intermittent multi-directional sports. We highlight that horizontal decelerations have a unique ground reaction force profile, characterised by high-impact peak forces and loading rates. The highest magnitude of these forces occurs during the early stance phase (< 50 ms) and is shown to be up to 2.7 times greater than those seen during the first steps of a maximal horizontal acceleration. As such, inability for either limb to tolerate these forces may result in a diminished ability to brake, subsequently reducing deceleration capacity, and increasing vulnerability to excessive forces that could heighten injury risk and severity of muscle damage. Two factors are highlighted as especially important for enhancing horizontal deceleration ability: (1) braking force control and (2) braking force attenuation. Whilst various eccentric strength qualities have been reported to be important for achieving these purposes, the potential importance of concentric, isometric and reactive strength, in addition to an enhanced technical ability to apply braking force is also highlighted. Last, the review provides recommended research directions to enhance future understanding of horizontal deceleration ability.

The Acute Effects of Heavy Sled Towing on Acceleration Performance and Sprint Mechanical and Kinematic Characteristics

The aim of this study was to investigate the effects of heavy sled towing using a load corresponding to a 50% reduction of the individual theoretical maximal velocity (ranged 57–73% body mass) on subsequent 30 m sprint performance, velocity, mechanical variables (theoretical maximal horizontal force, theoretical maximal horizontal velocity, maximal mechanical power output, slope of the linear force–velocity relationship, maximal ratio of horizontal to total force and decrease in the ratio of horizontal to total force) and kinematics (step length and rate, contact and flight time). Twelve (n = 5 males and n = 7 females) junior running sprinters performed an exercise under two intervention conditions in random order. The experimental condition (EXP) consisted of two repetitions of 20 m resisted sprints, while in the control condition (CON), an active recovery was performed. Before (baseline) and after (post) the interventions, the 30 m sprint tests were analyzed. Participants showed faster 30 m sprint times following sled towing (p = 0.005). Running velocity was significantly higher in EXP at 5–10 m (p = 0.032), 10–15 m (p = 0.006), 15–20 m (p = 0.004), 20–25 m (p = 0.015) and 25–30 m (p = 0.014). No significant changes in sprint mechanical variables and kinematics were observed. Heavy sled towing appeared to be an effective post-activation potentiation stimulus to acutely enhance sprint acceleration performance with no effect on the athlete’s running technique.

Sprint acceleration force-velocity-power characteristics in drafted vs non-drafted junior Australian football players: preliminary results

This investigation aimed to compare the maximal sprint acceleration profiles of drafted and non-drafted elite junior Australian football (AF) players. Nineteen players (10 drafted and 9 non-drafted) from an elite junior AF state team participated in this study. Instantaneous velocity was measured via radar gun during maximal 30 m sprints. The velocity-time data were analysed to derive individual force-velocity-power characteristics and sprint times. No significant differences existed between groups, however drafted players reached moderately faster maximum velocity (Hedges' g = 0.70 [-0.08; 1.48] and theoretical maximum velocity (g = 0.65 [-0.13; 1.42]) than non-drafted players indicating a superior ability to apply higher amounts of force at increasing sprinting velocity. Further, drafted players produced moderately higher absolute theoretical maximum force (g = 0.72 [-0.06; 1.50]) and absolute maximum power (g = 0.83 [0.04; 1.62]) which reflects their moderately higher body mass (g = 0.61[-0.16;1.38]). Although not significant, in this sample of elite junior AF players, those drafted into the AFL displayed greater absolute sprint acceleration characteristics and maximal velocity capabilities than their non-drafted counterparts (moderate effect size). Whether force-velocity-power characteristics can be more beneficial in differentiating sprint performance of elite junior Australian footballers compared to the traditional sprint time approach warrants further investigation with a larger sample size.

The Association Between Force-Velocity Relationship in Countermovement Jump and Sprint With Approach Jump, Linear Acceleration and Change of Direction Ability in Volleyball Players

The force-velocity (FV) relationship allows the identification of the mechanical capabilities of musculoskeletal system to produce force, power and velocity. The aim of this study was to assess the associations of the mechanical variables derived from the FV relationship with approach jump, linear sprint and change of direction (CoD) ability in young male volleyball players. Thirty-seven participants performed countermovement jumps with incremental loads from bodyweight to 50–100 kg (depending on the individual capabilities), 25-m sprint with split times being recorded for the purpose of FV relationship calculation, two CoD tests (505 test and modified T-test) and approach jump. Results in this study show that approach jump performance seems to be influenced by maximal power output (r = 0.53) and horizontal force production (r = 0.51) in sprinting, as well as force capacity in jumping (r = 0.45). Only the FV variables obtained from sprinting alone contributed to explaining linear sprinting and CoD ability (r = 0.35–0.93). An interesting finding is that sprinting FV variables have similar and some even stronger correlation with approach jump performance than jumping FV variables, which needs to be considered for volleyball training optimization. Based on the results of this study it seems that parameters that refer to horizontal movement capacity are important for volleyball athletic performance. Further interventional studies are needed to check how to implement specific FV-profile-based training programs to improve specific mechanical capabilities that determine volleyball athletic performance and influence the specific physical performance of volleyball players.

Association and Predictive Ability of Jump Performance with Sprint Profile of Collegiate Track and Field Athletes

This study examined the relationship between broad jump (BJ), countermovement jump (CMJ) and light load countermovement jump (LL-CMJ) performance and sprint performance and Sprint Profile measures in athletes. Additionally, this study aimed to determine the predictive ability of jump measures on Sprint Profile components. Twenty-five athletes performed BJ, CMJ, LL-CMJ, 30-metre acceleration and 30-metre maximal speed fly-by sprints. Results revealed moderate to very large correlations between BJ, CMJ and LL-CMJ performance with acceleration sprint completion times (r = -0.423 to -0.807; p < 0.05), fly-by sprint completion times (r = -0.452 to -0.838; p < 0.05) and maximal sprint speed (r = 0.424 to 0.794; p < 0.05). Additionally, associations were observed with multiple jumping measures and components of the Sprint Profile (r = 0.431 to 0.777; p < 0.05) during acceleration sprints. Furthermore, the BJ distance was the best predictor of Sprint Profile components during acceleration sprints (R2 = 0.57-0.76; p < 0.01) and maximal speed fly-by sprints (R2 = 0.775; p < 0.001). The forces and the manner of force application during the BJ to propel the athlete forwards and upwards are similar to those necessary to exhibit superior sprint performance. This may be due to the rapid generation of forces and orientation of force application during both movements.

Ratio of forces during sprint acceleration: A comparison of different calculation methods

The orientation of the ground reaction force (GRF) vector is a key determinant of human sprint acceleration performance and has been described using ratio of forces (RF) which quantifies the ratio of the antero-posterior component to the resultant GRF. Different methods have previously been used to calculate step-averaged RF, and this study therefore aimed to compare the effects of three calculation methods on two key "technical" ability measures: decline in ratio of forces (D_RF) and theoretical maximal RF at null velocity (RF₀). Twenty-four male sprinters completed maximal effort 60 m sprints from block and standing starts on a fully instrumented track (force platforms in series). RF-horizontal velocity profiles were determined from the measured GRFs over the entire acceleration phase using three different calculation methods for obtaining an RF value for each step: A) the mean of instantaneous RF during stance, B) the step-averaged antero-posterior component divided by the step-averaged resultant GRF, C) the step-averaged antero-posterior component divided by the resultant of the step-averaged antero-posterior and vertical components. Method A led to significantly greater RF₀ and shallower D_RF slopes than Methods B and C. These differences were very large (Effect size Cohen's d = 2.06 - 4.04) and varied between individuals due to differences in the GRF profiles, particularly during late stance as the acceleration phase progressed. Method B provides RF values which most closely approximate the mechanical reality of step averaged accelerations progressively approaching zero and it is recommended for future analyses although it should be considered a ratio of impulses.

The Training of Medium- to Long-Distance Sprint Performance in Football Code Athletes: A Systematic Review and Meta-analysis

Background

Within the football codes, medium-distance (i.e., > 20 m and ≤ 40 m) and long-distance (i.e., > 40 m) sprint performance and maximum velocity sprinting are important capacities for success. Despite this, no research has identified the most effective training methods for enhancing medium- to long-distance sprint outcomes.

Objectives

This systematic review with meta-analysis aimed to (1) analyse the ability of different methods to enhance medium- to long-distance sprint performance outcomes (0–30 m, 0 to > 30 m, and the maximum sprinting velocity phase [V_max]) within football code athletes and (2) identify how moderator variables (i.e., football code, sex, age, playing standard, phase of season) affected the training response.

Methods

We conducted a systematic search of electronic databases and performed a random-effects meta-analysis (within-group changes and pairwise between-group differences) to establish standardised mean differences (SMDs) with 95% confidence intervals and 95% prediction intervals. This identified the magnitude and direction of the individual training effects of intervention subgroups (sport only; primary, secondary, tertiary, and combined training methods) on medium- to long-distance sprint performance while considering moderator variables.

Results

In total, 60 studies met the inclusion criteria (26 with a sport-only control group), totalling 111 intervention groups and 1500 athletes. The within-group changes design reported significant performance improvements (small–moderate) between pre- and post-training for the combined, secondary (0–30 and 0 to > 30 m), and tertiary training methods (0–30 m). A significant moderate improvement was found in the V_max phase performance only for tertiary training methods, with no significant effect found for sport only or primary training methods. The pairwise between-group differences design (experimental vs. control) reported favourable performance improvements (large SMD) for the combined (0 to > 30 m), primary (V_max phase), secondary (0–30 m), and tertiary methods (all outcomes) when compared with the sport-only control groups. Subgroup analysis showed that the significant differences between the meta-analysis designs consistently demonstrated a larger effect in the pairwise between-group differences than the within-group change. No individual training mode was found to be the most effective. Subgroup analysis identified that football code, age, and phase of season moderated the overall magnitude of training effects.

Conclusions

This review provides the first systematic review and meta-analysis of all sprint performance development methods exclusively in football code athletes. Secondary, tertiary, and combined training methods appeared to improve medium-long sprint performance of football code athletes. Tertiary training methods should be implemented to enhance V_max phase performance. Nether sport-only nor primary training methods appeared to enhance medium to long sprint performance. Performance changes may be attributed to either adaptations specific to the acceleration or V_max phases, or both, but not exclusively V_max. Regardless of the population characteristics, sprint performance can be enhanced by increasing either the magnitude or the orientation of force an athlete can generate in the sprinting action, or both.

Trial Registration

OSF registration https://osf.io/kshqn/.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40279-021-01552-4.

Sprint and Jump Mechanical Profiles in Academy Rugby League Players: Positional Differences and the Associations between Profiles and Sprint Performance

This cross-sectional study evaluated the sprint and jump mechanical profiles of male academy rugby league players, the differences between positions, and the associations between mechanical profiles and sprint performance. Twenty academy rugby league players performed 40-m sprints and squat jumps at increasing loads (0-80 kg) to determine individual mechanical (force-velocity-power) and performance variables. The mechanical variables (absolute and relative theoretical maximal force-velocity-power, force-velocity linear relationship, and mechanical efficiency) were determined from the mechanical profiles. Forwards had significantly (p < 0.05) greater vertical and horizontal force, momentum but jumped lower (unloaded) and were slower than backs. No athlete presented an optimal jump profile. No associations were found between jump and sprint mechanical variables. Absolute theoretical maximal vertical force significantly (p < 0.05) correlated (r = 0.71-0.77) with sprint momentum. Moderate (r = -0.47) to near-perfect (r = 1.00) significant associations (p < 0.05) were found between sprint mechanical and performance variables. The largest associations shifted from maximum relative horizontal force-power generation and application to maximum velocity capabilities and force application at high velocities as distance increased. The jump and sprint mechanical profiles appear to provide distinctive and highly variable information about academy rugby league players' sprint and jump capacities. Associations between mechanical variables and sprint performance suggest horizontal and vertical profiles differ and should be trained accordingly.

Maximizing Acceleration and Change of Direction in Sport: A Case Series to Illustrate How the Force-Velocity Profile Provides Additional Information to That Derived from Linear Sprint Time

Sprint running and change of direction (COD) present similar mechanical demands, involving an acceleration phase in which athletes need to produce and apply substantial horizontal external force. Assessing the mechanical properties underpinning individual sprint acceleration might add relevant information about COD performance in addition to that obtained through sprint time alone. The present technical report uses a case series of three athletes with nearly identical 20 m sprint times but with different mechanical properties and COD performances. This makes it possible to illustrate, for the first time, a potential rationale for why the sprint force-velocity (FV) profile (i.e., theoretical maximal force (F₀), velocity (V₀), maximal power output (P_max), ratio of effective horizontal component (RF_peak) and index of force application technique (D_RF)) provides key information about COD performance (i.e., further to that derived from simple sprint time), which can be used to individualize training. This technical report provides practitioners with a justification to assess the FV profile in addition to sprint time when the aim is to enhance sprint acceleration and COD performance; practical interpretations and advice on how training interventions could be individualized based on the athletes' differential sprint mechanical properties are also specified.

The force-velocity profile as determinant of spike and serve ball speed in top-level male volleyball players

Understanding the relationship between mechanical variables derived from actions such as jumping, sprinting, or ballistic bench press throwing and sport-specific performance moves is of scientific and practical interest for strength and conditioning coaches for improving training programs. We examined the association between mechanical variables derived from the force-velocity (FV) profiles of the aforementioned actions and spike and serve ball speeds in elite volleyball players. Twenty-two male elite volleyball players (age: 24.3 ± 4.5 years; height: 1.89 ± 0.06 m; body mass: 86.3 ± 8.6 kg) were tested in two sessions. Squatting, sprinting, and bench press throwing FV profiles were determined in the first session, while spike and serve ball speeds were assessed in the second session. The theoretical maximal force (F0) of vertical jumping, the theoretical maximal velocity of sprinting, and the F0 of bench press throwing in ascending order, were strongly associated (rs range 0.53-0.84; p<0.05) with spike and serve ball speeds. These mechanical variables explained 20%-36% of the variability in spike and serve ball speeds, with a greater influence on the serve speed. These results suggest that assessing jumping, sprinting, and bench press throwing force-velocity profiles might help provide player-specific training programs and optimize performance in these technical-tactical actions in male elite volleyball players.

Why Are Masters Sprinters Slower Than Their Younger Counterparts? Physiological, Biomechanical, and Motor Control Related Implications for Training Program Design

Elite sprint performances typically peak during an athlete's 20s and decline thereafter with age. The mechanisms underpinning this sprint performance decline are often reported to be strength-based in nature with reductions in strength capacities driving increases in ground contact time and decreases in stride lengths and frequency. However, an as-of-yet underexplored aspect of Masters sprint performance is that of age-related degradation in neuromuscular infrastructure, which manifests as a decline in both strength and movement coordination. Here, the authors explore reductions in sprint performance in Masters athletes in a holistic fashion, blending discussion of strength and power changes with neuromuscular alterations along with mechanical and technical age-related alterations. In doing so, the authors provide recommendations to Masters sprinters-and the aging population, in general-as to how best to support sprint ability and general function with age, identifying nutritional interventions that support performance and function and suggesting useful programming strategies and injury-reduction techniques.

Association of the vertical and horizontal force-velocity profile and acceleration with change of direction ability in various sports

This study aimed to assess the association of the mechanical variables derived from the force-velocity (FV) profile (i.e. theoretical maximal force [F₀], velocity [V₀] and maximal power output [P_max]) with change of direction (COD) performance in soccer, basketball and tennis players. Fifty-four male athletes (soccer n = 23; tennis n = 16; basketball n = 15) were assessed for the vertical (Vrt) and horizontal (Hzt) FV profiles, COD with the dominant (D) and nondominant (ND) legs, using the modified 505 test, and sprint. Hzt FV profile parameters showed stronger associations with performance than Vrt FV profile in the three sports. Specifically, the Hzt parameter most strongly associated with COD performance was F₀ in tennis (r = -0.83; p<0.001) and P_max in soccer and basketball (r = -0.79; p<0.001). Associations between sprint times and COD test ranged from (r = 0.73-0.82) in soccer players, (r = 0.74-0.87) in tennis players and (r = 0.62-0.85) in basketball players, respectively (p<0.05). Considering the whole sample and the random effect of the type of sports, an improvement in sprint acceleration (i.e. one N/kg increase in F₀ and one W/kg in P_max) was associated with -0.15 s and -0.04 s to complete the 505 test, respectively. In conclusion, our results suggest the potential usefulness of assessing the Hzt FV profile to maximize acceleration capabilities through training interventions which, in turn, may translate into improved COD performance. However, further longitudinal and experimental research is needed to confirm this hypothesis.

The Training of Short Distance Sprint Performance in Football Code Athletes: A Systematic Review and Meta-Analysis

Background

Short-sprint (≤ 20 m) performance is an important quality for success in the football codes. Therefore, developing an evidence base for understanding training methods to enhance short-sprint performance is key for practitioners. However, current systematic reviews are limited by (1) a lack of focus on football code athletes, (2) a lack of consideration of all training modalities and (3) a failure to account for the normal training practices undertaken by intervention groups within their analysis. Therefore, this review aimed to (1) conduct a systematic review of the scientific literature evaluating training interventions upon short-sprint performance within football code athletes, (2) undertake a meta-analysis to assess the magnitude of change of sport-sprint performance following training interventions and (3) identify how moderator variables affect the training response.

Methods

A systematic search of electronic databases was conducted. A random-effects meta-analysis was performed to establish standardised mean difference with 95% confidence intervals. This identified the magnitude and direction of the individual training effects of intervention subgroups (primary, secondary, combined-specific, tertiary and combined training methods) on short-sprint performance while considering moderator variables (i.e., football code, sex, age, playing standard, phase of season).

Results

121 studies met the inclusion criteria, totalling 3419 athletes. Significant improvements (small-large) were found between pre- and post-training in short-sprint performance for the combined, secondary, tertiary and combined-specific training methods. No significant effect was found for primary or sport only training. No individual mode was found to be the most effective. Between-subgroup analysis identified that football code, age, playing standard and phase of season all moderated the overall magnitude of training effects.

Conclusions

This review provides the largest systematic review and meta-analysis of short-sprint performance development methods and the only one to assess football code athletes exclusively. Practitioners can apply combined, secondary and tertiary training methods to improve short-sprint performance within football code athletes. The application of sport only and primary methods does not appear to improve short-sprint performance. Regardless of the population characteristics, short-sprint performance can be enhanced by increasing either or both the magnitude and the orientation of force an athlete can generate in the sprinting action.

Trial Registration

OSF registration https://osf.io/kshqn/.

Electronic supplementary material

The online version of this article (10.1007/s40279-020-01372-y) contains supplementary material, which is available to authorized users.

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.