The Relationship Between the Isometric Squat and Stretch Shortening Cycle Function and Sprint Acceleration Performance in Hurling Players.

ABSTRACT: Brady, CJ, Harrison, AJ, Flanagan, EP, Haff, GG, and Comyns, TM. The relationship between the isometric squat and stretch shortening cycle function and sprint acceleration performance in hurling players. J Strength Cond Res 38(6): e288-e298, 2024-The primary aim was to examine the relationship between sprint acceleration performance and the performance tests: isometric squat (ISqT), countermovement jump (CMJ), and reactive strength index (RSI). The secondary aim determined whether these tests could distinguish between sprint performance levels. Twenty-six male under-21 subjects completed the ISqT, with peak force (PF), relative PF, force at 100, 150, and 200 milliseconds (ms), and impulse (0-200 ms) measured. Jump height (JH) was calculated from the CMJ and RSI during the 10-5 repeated jump test. Subjects completed 3 × 30-m sprints with splits taken at 5, 10, 20, and 30 m. Pearson's product moment correlations were used to assess the relationships between measures, and independent samples t tests were used to determine whether differences existed in sprint ability of those in the top and bottom quartiles for force at 100 ms, CMJ, and RSI. Significant negative moderate correlations were reported between force at 100 ms and 0-5 m and 5-10 m, significant moderate and large negative correlations between CMJ and all splits and significant large correlations between RSI and splits over 5 m. Force at 100 ms distinguished between performance levels from 0 to 5 m, CMJ from 10 to 20 m, and RSI from 20 to 30 m; faster subjects produced significantly higher force, JHs, and RSI scores. Three principal components explaining 86.1% of the variation in the data set were identified: sprint times and stretch shortening cycle capabilities (33.3%), time-specific force (29.9%), and absolute and relative strength (22.8%).

A noninvasive eDNA tool for detecting sea lamprey larvae in river sediments: Analytical validation and field testing in a low-abundance ecosystem.

Anthropogenic activities are increasingly threatening aquatic biodiversity, especially anadromous species. Monitoring and conservation measures are thus required to protect, maintain and restore imperilled populations. While many species can be surveyed using traditional capture and visual census techniques, species that use riverine habitats in a less conspicuous manner, such as sea lamprey Petromyzon marinus, can be more challenging to monitor. Sea lamprey larvae (ammocoetes) can spend several years in freshwater burrowed within soft sediments, inhibiting their detection and assessment. Here, we present a qPCR assay based on the detection of environmental DNA (eDNA) to identify the presence of ammocoetes burrowed in the sediment. We present an extensively validated method that ensured both species-specificity of the assay as well as the capacity to detect ammocoetes when abundances are low. Experiments on burrowing activity suggested that most of the DNA released into the sediment occurs during burrowing. Overall, we demonstrate this new molecular-based tool is an efficient and effective complement to traditional monitoring activities targeting larval stages of sea lampreys.

An Examination of the Relationship Between the Functional Movement Screen, Landing Error Scoring System, and 3D Kinematic Data During a Drop Jump Task.

ABSTRACT: Everard, E, Lyons, M, and Harrison, AJ. An examination of the relationship between the functional movement screen, landing error scoring system and 3D kinematic data during a drop jump task. J Strength Cond Res 35(11): 3012-3020, 2021-Tests such as the Functional Movement Screen (FMS) and Landing Error Scoring System (LESS) have become an established component of preparticipation screening. Despite their practical use, there is a lack of empirical evidence examining their relationship to established assessments of movement, such as 3D kinematics of a drop jump. Fifty-two male collegiate athletes undertook the LESS, FMS, and a drop jump where 3D lower-limb kinematic variables were assessed. Spearman correlations were conducted to examine the relationship between LESS, FMS, and drop-jump 3D kinematic variables. A series of independent t-tests examined differences in hip and knee kinematic variables in acceptable and poor FMS and LESS groups as determined by established cut-off scores. Landing Error Scoring System scores had significant moderate correlations with most kinematic variables (r = 0.35-0.64; p < 0.01). Subjects with poor LESS scores displayed significantly worse lower-limb kinematics compared with their high-scoring counterparts (effect size = 1.99-2.76, large effect). There were significant moderate correlations with maximal hip and knee flexion (r = 0.46 and 0.39 respectively; p < 0.01) and small or nonsignificant correlations between all other kinematic variables and FMS scores. Hip flexion and knee valgus at maximal displacement were the only kinematic variables significantly different between FMS groups (ES = 0.70-0.72, small-to-moderate effect). The results confirm limitations in the ability of the FMS to distinguish between groups for landing biomechanics.

Resistance Training Practices of Sprint Coaches.

ABSTRACT: Healy, R, Kenny, IC, and Harrison, AJ. Resistance training practices of sprint coaches. J Strength Cond Res 35(7): 1939-1948, 2021-This study describes the results of a survey of resistance training practices of sprint coaches. This study investigated why sprint coaches prescribe resistance training to their athletes, what exercises they select, and what factors are involved with their selection. Forty-one of 73 (56%) sprint coaches with mean ± SD coaching experience of 8.4 ± 6.4 years were included in this study. Coaches completed an online questionnaire consisting of 5 sections: (a) informed consent, (b) coach background information, (c) coach education and qualifications, (d) coaches' views on resistance training, and (e) exercise selection and preference. The results showed that coaches prescribe resistance training to their sprint athletes to develop strength and power, which they believe will transfer to sprint performance. Coaches prescribed a wide variety of traditional, ballistic, and plyometric exercises, with the hurdle jump found to be the most widely prescribed exercise (93% of coaches surveyed). Coaches selected exercises for a variety of reasons; however, the 3 most prominent reasons were: (a) performance adaptations; (b) practicality; and (c) the targeting of muscles/muscle groups. Coaches prioritized exercises that specifically developed strength, power, and reactive strength for their sprint athletes. This research can be used to develop educational resources for sprint coaches who wish to use resistance training with their athletes. In addition, sprint coaches can use the data presented to expand their current exercise repertoire and resistance training practices.

Measures of Strength and Jump Performance Can Predict 30-m Sprint Time in Rugby Union Players.

ABSTRACT: Furlong, L-AM, Harrison, AJ, and Jensen, RL. Measures of strength and jump performance can predict 30-m sprint time in Rugby Union players. J Strength Cond Res 35(9): 2579-2583, 2021-Performance and fitness monitoring in Rugby Union often include jumping, sprinting, and strength tests, but repeatability of and relationships between these measures are unclear. The level of interindividual variability in these relationships and their sprint time predictive capabilities are also unknown. This study examined the reliability of, and relationship between, countermovement (CMJJH), squat (SJJH), and rebound (RBJJH) jump heights, rebound jump contact time (RBJCT), estimated 1 repetition maximum back squat relative to body mass (SQBM), and reactive strength index (RSI) to 30-m sprint time of subelite, semiprofessional Rugby Union players. Measurement reliability was very good, with high average intraclass correlation coefficients (≥0.9) and low coefficient of variation (<10.1%). All variables were significantly (p < 0.01) correlated to each other (r > 0.575), except for SQBM (only related to CMJJH, r = 0.621) and RBJCT (only related to RSI, r = -0.727). SJJH and SQBM were the strongest and most consistent predictors of time to 30 m (R = 0.754 ± 0.081; SEE = 0.166 ± 0.025), but variability in SEE magnitude was observed across the group during bootstrapping. Cross-validation showed a mean difference between actual and predicted 30 m times equivalent to 0.22% of the group average time to 30 m. These results support the importance of multiple aspects of fitness training in Rugby Union players for improving performance in short-duration sprinting activities, but highlight the individual nature of their relative importance. Measures of strength and power can be used to predict short sprint performance by the strength and conditioning professional.

Examining the Reliability of the Landing Error Scoring System With Raters Using the Standardized Instructions and Scoring Sheet.

CONTEXT: Dynamic movement-based screens, such as the Landing Error Scoring System (LESS), are becoming more widely used in research and practical settings. Currently, 3 studies have examined the reliability of the LESS. These studies have reported good interrater and intrarater reliability. However, all 3 studies involved raters, who were founders of the LESS. Therefore, it is unclear whether the reliability reported reflects that which would be observed with practitioners without such specialized and intimate knowledge of the screen and only using the standardized set of instructions. OBJECTIVE: To investigate the interrater and intrarater reliability of the final score and the individual scoring criteria of the LESS. DESIGN: Reliability protocol. SETTING: Controlled laboratory. PARTICIPANTS: Two raters scored 30 male participants (age = 21.8 [3.9] y; height = 1.75 [0.46] m; mass = 75.5 [6.6] kg) involved in a variety of college sports. MAIN OUTCOME MEASURE: Two raters using only the standardized scoring sheet assessed the interrater reliability of the total score and individual scoring criteria independently of each other. The principal author scored the videos again 6 weeks later for the intrarater reliability component of the study. INTERVENTION: Participants performed a drop box landing from a 30-cm box was recorded with a video camera from the front and side views. RESULTS: The intraclass coefficients interrater and intrarater reliability for the total scores were excellent (intraclass coefficients range = .95 and .96; SEM = 1.01 and 1.02). The individual scoring criteria of the LESS had between moderate and perfect agreement using kappa statistics (κ = .41-1.0). CONCLUSION: The final score and individual scoring criteria of the LESS have acceptable reliability with raters using the standardized scoring sheet. Practitioners using only the standardized scoring sheet should feel confident that the LESS is a reliable tool.

The effects of added mass on the biomechanics and performance of countermovement jumps.

This study examined the kinetic and temporal differences between countermovement jumps (CMJs) and eccentrically loaded CMJs. A survey of 109 coaches and athlete showed that 87% of respondents regularly used jumps with added mass within training. Sixteen male and thirteen female track and field athletes from sprinting, hurdling and jumping events performed 5 bodyweight CMJs 5 jumps wearing a weighted jacket and 5 eccentrically loaded dumbbell (LDB) jumps trials in a randomised order. Peak force (PF), peak power (PP), flight time (FT), concentric time (CON-T), eccentric time (ECT), total time (TIME) and eccentric/concentric ratio (E/C-Ratio) were obtained from force plate data. Statistically significant differences (p < 0.05) with moderate to large magnitude effect sizes were found between men and women in FT, PP and PF but not in any of the temporal variables. The results indicated that the WJ decreased FT in men (↓9%) and women (↓10%) but LDB jumps had similar FT to CMJ. Overall, the results showed that LDB increased the E/C Ratio (↑50% and ↑42%) and decreased CON-T (↓37% and ↓25%) compared with WJ and CMJ respectively. LDB jumping is not recommended as a training modality as it tends to disrupt the relative timing of the jump action.

Application of the principal component waveform analysis to identify improvements in vertical jump performance.

The purpose of this study was to determine the effects of training on the force-, velocity-, and displacement-time curves using principal component analysis (PCA) to examine the pre to post intervention changes. Thirty-four trained women basketball players were randomly divided into training and control groups. The training intervention consisted of full squats combined with repeated jumps. The effects of the intervention were analysed before and after the training period of 6 weeks by comparing the principal component scores. The magnitude of differences within-/between-group were calculated and expressed as standardised differences. After the intervention period, clear changes in principal components were observed in the training group compared to the control group. These were related to the execution of a vertical jump with a faster and deeper countermovement that was stopped with greater force. This resulted in greater force from the start of the upward movement phase which was maintained for a longer time. This increase in force throughout a greater range of motion increased the take-off velocity and consequently jumping height.

Does fundamental movement skill proficiency vary by sex, class group or weight status? Evidence from an Irish primary school setting.

This study examined fundamental movement skill (FMS) proficiency among male (N = 216) and female (N = 198) Irish primary school pupils from Year 2 to Year 7 (9.0 ± 1.7 years). Following anthropometric measurements, participants were video-recorded performing 15 FMS and scored using the TGMD-3, Victorian Fundamental Movement skills Manual and the Get skilled: Get active guidelines. Percentage mastery ranged between 1.4% (gallop) and 35.7% (slide). A two-way ANOVA evaluated the effect of sex (male/female) and class group (Year 2/3/4/5/6/7) on individual skills, locomotor subtest, object-control subtest and total TGMD-3 (GMQ) scores. No significant sex ×class interaction effects were found. Large effect sizes were reported for male superiority in object-control subtest (ηp2 = 0.26) and GMQ (ηp2 = 0.16) scores (both p < 0.001). Older classes had higher object-control subtest scores than younger classes, but scores plateaued after Year 5. Furthermore, overweight participants had significantly lower locomotor subtest (p < 0.001, d = 0.7), object-control subtest (p = 0.03, d = 0.3) and GMQ scores (p < 0.001, d = 0.5) than non-overweight participants. This study highlights very poor levels of FMS mastery among Irish schoolchildren and stresses the need for developmentally appropriate, FMS intervention programmes that are inclusive regardless of age, sex or weight status.

Influence of Reactive and Maximum Strength Indicators on Sprint Performance.

Healy, R, Smyth, C, Kenny, IC, and Harrison, AJ. Influence of reactive and maximum strength indicators on sprint performance. J Strength Cond Res 33(11): 3039-3048, 2019-The primary aim of this study was to assess the relationship between reactive and maximal strength measures with 40 m sprint performance and mechanical properties. Fourteen male and 14 female sprinters participated in this study. On the first day, subjects performed 40 m sprints with 10-m split times recorded in addition to maximal theoretical velocity, maximal theoretical force and peak horizontal power, which were calculated from force-velocity relationships. On the second day, subjects performed isometric midthigh pulls (IMTPs) with peak force (PF) and relative PF calculated, drop jumps (DJs) and vertical hopping where the reactive strength index (RSI) was calculated as jump height (JH) divided by contact time (CT). Pearson correlations were used to assess the relationships between measures and independent samples t-tests were used to assess the differences between men and women. No significant correlations were found between DJ and hopping RSI and sprint measures. A significant strong positive correlation was found between IMTP PF and peak horizontal power in men only (r = 0.61). The male sprinters performed significantly better in all recorded measures apart from hopping (CT, JH and RSI) and DJ CT where no significant differences were found. The lack of association between reactive and maximal strength measures with sprint performance is potentially because of the test's prolonged CTs relative to sprinting and the inability to assess the technical application of force. Several methods of assessing reactive strength are needed that can better represent the demands of the distinct phases of sprinting e.g., acceleration, maximum velocity.

Effects of running experience on coordination and its variability in runners.

The purpose of this study was to examine the differences in coordination variability in running gait between trained runners and non-runners using continuous relative phase (CRP) analysis. Lower extremity kinematic data were collected for 22 participants during the stance phase. The participants were assigned to either a runner or non-runner group based on running volume training. Segment coordination and coordination variability were calculated for selected hip-knee and knee-ankle couplings. Independent t-tests and magnitude-based inferences were used to compare the 2 groups. There were limited differences in the CRP and its variability among runners and non-runner groups. The runners group achieved moderately lower coordination compared with non-runners group in the phase angle for hip abduction/adduction and knee flexion/extension. The runners tended to show moderately lower coordination variability in the phase angle for knee flexion/extension and subtalar inversion/eversion in comparison to non-runners group. These results suggested that levels of experience as estimated from weekly training volume had little influence on coordination and its variability.

Dry-Land Resistance Training Practices of Elite Swimming Strength and Conditioning Coaches.

Crowley, E, Harrison, AJ, and Lyons, M. Dry-land resistance training practices of elite swimming strength and conditioning coaches. J Strength Cond Res 32(9): 2592-2600, 2018-No research to date has investigated dry-land resistance (RT) training practices of elite swimming strength and conditioning coaches. This is the first comprehensive study exploring dry-land RT training practices in swimming. The aims of this study were to examine (a) the dry-land RT training practices and exercises used by elite swimming strength and conditioning coaches and (b) the rationale provided by coaches about their practices and prescription of specific dry-land RT training exercises. Twenty-three (n = 21 males, n = 2 females) elite swimming strength and conditioning coaches, from Ireland (n = 7), Great Britain (n = 5), Australia (n = 6), and the United States of America (n = 5) were recruited through their specific national governing bodies. Coaches completed an online questionnaire consisting of 7 sections; subject information, informed consent, coach's biography, coach education, current training commitments, dry-land RT training practices and exercises, and additional information. The results showed that coaches had varying levels of experience, education and worked with different level swimmers. A total of 95 dry-land RT training exercises were used by the coaches across 4 different dry-land RT training practices (warm-up, circuit training, traditional RT training and plyometrics). Traditional RT training (87%) was the most commonly practiced. The pull-up and squat were the most popular dry-land RT training exercises used by elite swimming strength and conditioning coaches. Future research needs to focus on exploring the specificity and the transfer of RT training exercises to swimming performance.

Effects of false-start disqualification rules on response-times of elite-standard sprinters.

The 100 ms ruling for false start disqualification at athletic competitions governed by the International Association of Athletics Federations has been in force since the early 1990s. Throughout this period, there have been marked changes to the rules that govern the disqualification of athletes from sprint events incorporating starts from blocks. This study analysed all available World and European Championship response-time (RT) data from 1999 to 2014 to examine effects of rule changes on competition RT at major championships. The exponentially modified Gaussian distribution was used to model RT and make comparisons relative to athletes' sex, ruling periods and competition rounds. Revised RT thresholds of 115 ms and 119 ms were identified for men and women, respectively, indicating that the current 100 ms rule could result in some false starts not being detected in competitive athletics. The study proposes that when using existing International Association of Athletics Federations approved systems, the false start detection threshold should be increased and that men and women athletes should have different thresholds because of substantial evidence of a sex-based difference in RT in elite-standard athletes.

HIIT enhances endurance performance and aerobic characteristics more than high-volume training in trained rowers.

This study compared the effects of long slow distance training (LSD) with high-intensity interval training (HIIT) in rowers. Nineteen well-trained rowers performed three tests before and after an 8-week training intervention: (1) 2000 m time trial; (2) seven-stage incremental step test to determine maximum oxygen uptake ([Formula: see text]O2max), power output at [Formula: see text]O2max (W[Formula: see text]O2max), peak power output (PPO), rowing economy and blood lactate indices and (3) seven-stroke power-output test to determine maximal power output (Wmax) and force (Fmax). After baseline testing, participants were randomly assigned either to a HIIT or LSD group. The LSD comprised 10 weekly aerobic sessions. The HIIT also comprised 10 weekly sessions: 8 aerobic and 2 HIIT. The HIIT sessions comprised 6-8 × 2.5 min intervals at 100% PPO with recovery time based on heart rate (HR) returning to 70% HRmax. Results demonstrated that the HIIT produced greater improvement in 2000 m time trial performance than the LSD (effect size (ES) = 0.25). Moreover, the HIIT produced greater improvements in [Formula: see text]O2max (ES = 0.95, P = 0.035) and power output at lactate threshold (WLT) (ES = 1.15, P = 0.008). Eight weeks of HIIT performed at 100% PPO is more effective than LSD in improving performance and aerobic characteristics in well-trained rowers.

Examining the Relationship Between the Functional Movement Screen and the Landing Error Scoring System in an Active, Male Collegiate Population.

Everard, EM, Harrison, AJ, and Lyons, M. Examining the relationship between the functional movement screen and the landing error scoring system in an active, male collegiate population. J Strength Cond Res 31(5): 1265-1272, 2017-In recent years, there has been an increasing focus on movement screening as the principal aspect of preparticipation testing. Two of the most common movement screening tools are the Functional Movement Screen (FMS) and the Landing Error Scoring System (LESS). Several studies have examined the reliability and validity of these tools, but so far, there have been no studies comparing the results of these 2 screening tools against each other. Therefore, the purpose of this study was to determine the relationship between FMS scores and LESS scores. Ninety-eight male college athletes actively competing in sport (Gaelic games, soccer, athletics, boxing/mixed martial arts, Olympic weightlifting) participated in the study and performed the FMS and LESS screens. Both the 21-point and 100-point scoring systems were used to score the FMS. Spearman's correlation coefficients were used to determine the relationship between the 2 screening scores. The results showed a significant moderate correlation between FMS and LESS scores (rho 100 and 21 point = -0.528; -0.487; p < 0.001). In addition, r values of 0.26 and 0.23 indicate a poor shared variance between the 2 screens. The results indicate that performing well in one of the screens does not necessarily equate to performing well in the other. This has practical implications as it highlights that both screens may assess different movement patterns and should not be used as a substitute for each other.

Kinetic and Kinematic Analysis for Assessing the Differences in Countermovement Jump Performance in Rugby Players.

Floría, P, Gómez-Landero, LA, Suárez-Arrones, L, and Harrison, AJ. Kinetic and kinematic analysis for assessing the differences in countermovement jump performance in rugby players. J Strength Cond Res 30(9): 2533-2539, 2016-The aim of this study was to ascertain the differences in kinetic and kinematic profiles between better and poorer performers of the vertical jump within a homogeneous group of trained adults. Fifty rugby players were divided into low scoring (LOW) and high scoring (HIGH) groups based on their performance in the vertical jump. The force, velocity, displacement, and rate of force development (RFD)-time curves were analyzed to determine the differences between groups. The analysis of the data showed differences in all the patterns of the ensemble mean curves of the HIGH and LOW groups. During the eccentric phase, the differences in the HIGH group with respect to the LOW group were lower crouch position, higher downward velocity, and higher force and RFD during the braking of the downward movement. During the concentric phase, the HIGH group achieved higher upward velocity, higher force at the end of phase, and a higher position at takeoff. The higher jump performances seem to be related to a more effective stretch-shortening cycle function that is characterized by a deeper and faster countermovement with higher eccentric forces being applied to decelerate the downward movement leading to enhanced force generation during the concentric phase.

An Examination of the True Reliability of Lower Limb Stiffness Measures During Overground Hopping.

Evidence suggests reports describing the reliability of leg-spring (kleg) and joint stiffness (kjoint) measures are contaminated by artifacts originating from digital filtering procedures. In addition, the intraday reliability of kleg and kjoint requires investigation. This study examined the effects of experimental procedures on the inter- and intraday reliability of kleg and kjoint. Thirty-two participants completed 2 trials of single-legged hopping at 1.5, 2.2, and 3.0 Hz at the same time of day across 3 days. On the final test day a fourth experimental bout took place 6 hours before or after participants' typical testing time. Kinematic and kinetic data were collected throughout. Stiffness was calculated using models of kleg and kjoint. Classifications of measurement agreement were established using thresholds for absolute and relative reliability statistics. Results illustrated that kleg and kankle exhibited strong agreement. In contrast, kknee and khip demonstrated weak-to-moderate consistency. Results suggest limits in kjoint reliability persist despite employment of appropriate filtering procedures. Furthermore, diurnal fluctuations in lower-limb muscle-tendon stiffness exhibit little effect on intraday reliability. The present findings support the existence of kleg as an attractor state during hopping, achieved through fluctuations in kjoint variables. Limits to kjoint reliability appear to represent biological function rather than measurement artifact.

Differences in plantarflexor function during a stretch-shortening cycle task due to limb preference.

Most healthy humans move symmetrically at gross limb level but large kinetic and kinematic asymmetries have been observed at joint level during locomotion. The aim of this study was to assess muscle function asymmetries in healthy, active adults using an adapted force sledge apparatus which isolates the plantarflexors during a stretch-shortening cycle (SSC) task. Peak force, rate of force development and SSC function of preferred and non-preferred limbs were assessed in 21 healthy, active individuals using the adapted sledge and three-dimensional motion analysis. Between-limb differences and relationships were determined using paired t-tests/Wilcoxon Signed-rank test, Cohen's dz, absolute symmetry index and Pearson's r/Spearman's rho. Significant differences with moderate effect size (ES) were observed in peak force (ES: 0.66), rate of peak force development (ES: 0.78), rate of force development in the first 50 ms (ES: 0.76), flight time (ES: 0.64) and SSC function (0.68), with no difference in contact time or duration of eccentric loading. A small ES (0.56) was observed in rate of force development in the first 30 ms. The upper range of asymmetry observed (up to 44.6%) was larger than previously reported for healthy individuals, indicating compensations occur at proximal joints during locomotion to ensure symmetrical movement.

Sprinting performance and resistance-based training interventions: a systematic review.

The purpose of this systematic review was to search the scientific literature for original research, addressing the effects different forms of resistance-based training have on sprinting performance in competitive sprinters. Specific key words (Sprinters OR Sprint) NOT (Rugby, Soccer, Cycling, Swimming, Paralympic, and Nutrition) were used to search relevant databases through November 2013 for related literature. Original research was reviewed using the Physiotherapy Evidence Database scale. Five studies met the inclusion criteria: actively competitive adult male sprinters who participated in a resistance-based intervention (>4 weeks), with outcome measures in the form of 10- to 100-m sprint times. Exclusion criteria included acute studies (<4 weeks), nonsprinting populations, and studies with no performance outcome measures (10- to 100-m sprint times). Three of the 5 studies used both locomotor resistance and fixed plane resistance, whereas the remaining 2 studies used more fixed plane resistance, for example, squat and leg extension. Three of the studies showed a statistical improvement in sprinting performance measures, for example, a decrease in 30-m sprint time (p = 0.044), whereas 1 study showed a decrease in sprinting performance. The analysis concluded that resistance-based training has a positive effect on sprinting performance. Varied input of locomotor resistance and fixed plane resistance has resulted in similar percentage change for sprinting performance. This review adds to the body of knowledge by strongly highlighting the dearth of literature exploring the effects of resistance-based training on sprinting performance in competitive sprinters. The short duration and wide range of exercises implemented in studies to date are of concern, but coaches should not hesitate to implement well-planned resistance programs for their sprint athletes.

Resisted sprints do not acutely enhance sprinting performance.

Sprinting speed is a vital component of successful performance in many sports. Long-term resisted sprint training has been shown to improve early acceleration performance, but the acute post-activation potentiation (PAP) effects of resisted sprinting on subsequent performance remain unclear. The purpose of this investigation was to examine the effects of resisted sprinting on sprinting and factors related to sprint performance. Twelve active males participated in a pretest involving ten 10-m sprints through dual-beam timing gates and 10-m Optojump Next System with full recovery. This provided baseline data on step rate, step length, ground contact time, and running speed over the first 6 steps of a maximum effort sprint. One week later, the participants performed three 10-m resisted sprints using a sled loaded to 25-30% body mass followed by a 10-m sprint at 1, 2, 4, 6, 8, and 10 minutes after the final resisted sprint. The data were analyzed using an adapted typical error analysis and repeated measures analysis of variance. The results using analysis of variance provided evidence of significant initial fatigue followed by the enhancement of mean step rate, contact time, reactive strength index, and running speed in 10-m sprints performed after the resisted sprinting (p > 0.05). By contrast, the typical error analysis showed that this enhancement was limited and unsystematic in nature with little clear evidence of fatigue followed by potentiation. The results using typical error data do not provide strong evidence of PAP in 10-m sprint performance after resisted sprinting.