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%).

Joint movement patterns differ among male recreational runners with different running style.

The purpose of this study was to analyse the differences in joint kinematic patterns among runners with different spatiotemporal characteristics in the running cycle. Lower extremity kinematic data and spatiotemporal stride parameters were collected for ninety-two recreational runners during a treadmill run at a self-selected comfortable speed. A K-means clustering analysis was conducted on normalised stride cadence and Duty Factor to identify running style. Cluster 1 characterised by reduced stance times and low Duty Factor; Cluster 2, long stance times and low stride cadence; Cluster 3, high Duty Factor and stride cadence. Functional principal component analysis was used to identify patterns of variability between runners. Runners who used a combination of high cadence and Duty Factor showed differences in hip, knee and ankle sagittal kinematics compared to other runners. On the contrary, the joint kinematics was not altered when the Duty Factor was increased along with a decrease in the stride cadence. This study has demonstrated that the combination of several spatial-temporal parameters of the running cycle should be considered when analysing the movement pattern of the lower limb.

Neuromuscular Plantar Flexor Performance of Sprinters versus Physically Active Individuals.

INTRODUCTION: Comparison of the neuromuscular performance of different athlete types may give insight into the in vivo variability of these measures and their underpinning mechanisms. The study aims to compare the neuromuscular function of the plantar flexors of sprinters and physically active individuals to assess any differences in explosive force performance. METHODS: Neuromuscular performance of a group of sprinters (highly trained/national level, n = 12; elite/international level, n = 2) and physically active individuals ( n = 14) were assessed during involuntary, explosive, and maximum voluntary isometric plantar flexions, across different muscle-tendon unit (MTU) lengths (10° plantarflexion, 0° (anatomical zero/neutral), and 10° dorsiflexion). Plantarflexion rate of torque development (RTD) was measured in three 50-ms time windows from their onset. The synchronous activation of the plantar flexor agonist muscles was calculated as the time difference between 1) the first and last muscle onset and 2) the onsets of the two gastrocnemii muscles. Muscle size and MTU stiffness were assessed using sonograms of the medial gastrocnemius and myotendinous junction. RESULTS: Sprinters exhibited greater involuntary RTD across time points (0-50 ms, 50-100 ms) and MTU lengths. In addition, sprinters demonstrated greater early phase voluntary RTD (0-50 ms, 50-100 ms) across MTU lengths. Sprinters also demonstrated greater late-phase RTD (100-150 ms), and relative maximal voluntary torque at the DF angle only. The sprinters demonstrated a more synchronous activation of the gastrocnemii muscles. There were no observable differences in muscle size and MTU stiffness between groups. CONCLUSIONS: These findings suggest sprint-specific training could be a contributing factor toward improved explosive performance of the plantar flexors, particularly in the early phase of muscular contraction, evidenced by the greater explosive torque producing capabilities of sprinters.

Ankle and Plantar Flexor Muscle-Tendon Unit Function in Sprinters: A Narrative Review.

Maximal sprinting in humans requires the contribution of various muscle-tendon units (MTUs) and joints to maximize performance. The plantar flexor MTU and ankle joint are of particular importance due to their role in applying force to the ground. This narrative review examines the contribution of the ankle joint and plantar flexor MTUs across the phases of sprinting (start, acceleration, and maximum velocity), alongside the musculotendinous properties that contribute to improved plantar flexor MTU performance. For the sprint start, the rear leg ankle joint appears to be a particularly important contributor to sprint start performance, alongside the stretch-shortening cycle (SSC) action of the plantar flexor MTU. Comparing elite and sub-elite sprinters revealed that elite sprinters had a higher rate of force development (RFD) and normalized average horizontal block power, which was transferred via the ankle joint to the block. For the acceleration phase, the ankle joint and plantar flexor MTU appear to be the most critical of the major lower limb joints/MTUs. The contribution of the ankle joint to power generation and positive work is minimal during the first stance, but an increased contribution is observed during the second stance, mid-acceleration, and late-acceleration. In terms of muscular contributions, the gastrocnemius and soleus have distinct roles. The soleus acts mainly as a supporter, generating large portions of the upward impulse, whereas the gastrocnemius acts as both an accelerator and a supporter, contributing significantly to propulsive and upward impulses. During maximum velocity sprinting the ankle joint is a net dissipater of energy, potentially due to the greater vertical loading placed on the plantar flexors. However, the ankle joint is critical for energy transfer from proximal joints to ground force application to maintain velocity. In terms of the contribution of musculoskeletal factors to ankle joint and plantar flexor performance, an optimal plantar flexor MTU profile potentially exists, which is possibly a combination of several musculoskeletal factors, alongside factors such as footwear and technique.

Seascape genomics reveals limited dispersal and suggests spatially varying selection among European populations of sea lamprey (Petromyzon marinus).

Sea lamprey Petromyzon marinus is an anadromous and semelparous fish without homing behaviors. Despite being a freshwater, free-living organism for a large part of their life cycle, its adulthood is spent as a parasite of marine vertebrates. In their native European range, while it is well-established that sea lampreys comprise a single nearly-panmictic population, few studies have further explored the evolutionary history of natural populations. Here, we performed the first genome-wide characterization of sea lamprey's genetic diversity in their European natural range. The objectives were to investigate the connectivity among river basins and explore evolutionary processes mediating dispersal during the marine phase, with the sequencing of 186 individuals from 8 locations spanning the North Eastern Atlantic coast and the North Sea with double-digest RAD-sequencing, obtaining a total of 30,910 bi-allelic SNPs. Population genetic analyses reinforced the existence of a single metapopulation encompassing freshwater spawning sites within the North Eastern Atlantic and the North Sea, though the prevalence of private alleles at northern latitudes suggested some limits to the species' dispersal. Seascape genomics suggested a scenario where oxygen concentration and river runoffs impose spatially varying selection across their distribution range. Exploring associations with the abundance of potential hosts further suggested that hake and cod could also impose selective pressures, although the nature of such putative biotic interactions was unresolved. Overall, the identification of adaptive seascapes in a panmictic anadromous species could contribute to conservation practices by providing information for restoration activities to mitigate local extinctions on freshwater sites.

Reliability of mechanical properties of the plantar flexor muscle tendon unit with consideration to joint angle and sex.

The reliability of mechanical measures can be impacted by the protocol used, including factors such as joint angle and the sex of participants. This study aimed to determine the inter-day reliability of plantar flexor mechanical measures across ankle joint angles and contraction types and consider potential sex-specific effects. 14 physically-active individuals participated in two identical measurement sessions involving involuntary and voluntary plantar flexor contractions, at three ankle angles (10° plantarflexion (PF), 0° (anatomical zero (AZ)), and 10° dorsiflexion (DF)), while torque and surface EMG were recorded. The reliability of mechanical parameters of maximal voluntary torque (MVT), rate of torque development (RTD), electromechanical delay, and tendon stiffness were assessed using absolute and relative reliability measures. MVT measures were reliable across ankle angles. RTD measures showed good group level reliability and moderate reliability for an individual during the early phase of contraction across ankle angles. Explosive voluntary torque measures tended to be less reliable from 50 ms onward, with varied reliability across angles for late-phase RTD. Tendon stiffness demonstrated the best reliability at the DF angle. Sex-based differences in the reliability of tendon measures found that females had significantly different initial tendon length between testing sessions. Despite this, tendon excursion, force, and stiffness measures demonstrated similar reliability compared to males. Ankle angle changes influence the reliability of plantar flexor mechanical measurements across contraction types, particularly for voluntary contractions. These results highlight the importance of establishing potential protocol effects on measurement reliability prior to quantifying plantar flexor mechanical measures.

Effects of task difficulty on centre of pressure excursion and its inter-trial variability in acrobatic gymnastics pyramid performance.

Despite the importance of balance in Acrobatic Gymnastic Pyramid performance, there is limited biomechanical analysis of balance during this activity. The aims of this study were to analyse the effect of pyramid difficulty on the centre of pressure (COP) excursion and its inter-trial variability, and determine which parameters had strongest relationship with performance. Forty-seven acrobatic gymnasts performed five trials of back and front pyramids and a third more difficult, handstand pyramid on a force platform. Pyramids were held for 7 seconds and surface area, range, mediolateral amplitude and anteroposterior amplitude of the CoP were examined to analyse balance. The pyramid scores were obtained from qualified judges to assess the performance. Results showed higher CoP excursions and inter-trial variability during the execution of the high difficulty pyramid. Higher judges' scores were associated with lower CoP excursions in all the pyramids regardless of the difficulty. Similarly, correlation between inter-trial variability and pyramid performance was observed, although these coefficients were lower than those reported for the relationship between CoP excursion and performance. These results suggested that CoP monitoring could help coaches and gymnasts to assess the pyramid instability more accurately.

Injury Trends for School Rugby Union in Ireland: The Need for Position-specific Injury-prevention Programs.

BACKGROUND: Concern has been raised over the injury risk to school Rugby union (Rugby) players and the potential long-term health consequences. Despite the increase in studies for this cohort, the influence of playing position on injury incidence and presentation is unclear. PURPOSE: To describe the incidence, nature and severity of match injuries for school Rugby in Ireland overall, and as a function of playing position. STUDY DESIGN: Prospective cohort study. METHODS: Data were collected from 15 male (aged 16-19 years) school Senior Cup teams across 2 seasons. In total, 339 players participated in season 1, whereas 326 players participated in season 2. Injury data were recorded onto a bespoke online platform. Match exposure was also recorded. RESULTS: The incidence rate of match injuries (24-hour time loss) was 53.6 per 1000 hours. Across both seasons, 6810 days were lost from play due to injury. Forwards (65.4 per 1000 hours) sustained significantly more (P < 0.05) injuries than backs (40.5 per 1000 hours). The head, shoulder, knee, and ankle were the most common injured body regions; however, forwards sustained significantly more (P < 0.05) head and shoulder injuries than backs. The tackle was responsible for the majority of injuries in both groups. The highest proportion of injuries occurred during the third quarter. CONCLUSION: Clear differences in injury presentation and incidence were evident when comparing forwards versus backs. The high rate of head and shoulder injuries in the forwards suggest the need for more targeted injury-prevention strategies and further research on education and laws around the tackle event. The spike of injuries in the third quarter suggests that fatigue or inadequate half-time warm-up may be a contributing factor warranting further exploration. CLINICAL RELEVANCE: This study demonstrates clear differences in injury presentation according to playing position in school Rugby and highlights the need for a more tailored approach to the design and implementation of injury-prevention strategies. LEVEL OF EVIDENCE: Level 3.

Instructional review of key factors to achieve successful outcomes when using low-intensity pulsed ultrasound in fracture repair.

Low-intensity pulsed ultrasound (LIPUS) treatment of fractures has been available to the orthopaedic community for nearly three decades; however, it is still considered an experimental treatment by some clinicians, even though there is a wealth of clinical data. Based on the evaluation of clinical trial data, we have established key criteria which can lead to LIPUS success and avoid failure. These are fracture gap size and stability, accurate transducer placement and minimum treatment number. However, from a clinician's view, the correct attitude to treatment must be observed, and this has also been discussed. It is hoped, armed with this new evaluation of the clinical data, that clinicians can treat patients with LIPUS more effectively, resulting in fewer failures of treatment.

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.

Profiling elite male 100-m sprint performance: The role of maximum velocity and relative acceleration.

PURPOSE: This study aimed to determine the accuracy of a 4 split time modelling method to generate velocity-time and velocity-distance variables in elite male 100-m sprinters and subsequently to assess the roles of key sprint parameters with respect to 100-m sprint performance. Additionally, this study aimed to assess the differences between faster and slower sprinters in key sprint variables that have not been assessed in previous work. METHODS: Velocity-time and velocity-distance curves were generated using a mono-exponential function from 4 split times for 82 male sprinters during major athletics competitions. Key race variables-maximum velocity, the acceleration time constant (τ), and percentage of velocity lost (vLoss)-were derived for each athlete. Athletes were divided into tertiles, based on 100-m time, with the first and third tertiles considered to be the faster and slower groups, respectively, to facilitate further analysis. RESULTS: Modelled split times and velocities displayed excellent accuracy and close agreement with raw measures (range of mean bias was -0.2% to 0.2%, and range of intraclass correlation coefficients (ICCs) was 0.935 to 0.999) except for 10-m time (mean bias was 1.6% ± 1.3%, and the ICC was 0.600). The 100-m sprint performance time and all 20-m split times had a significant near-perfect negative correlation with maximum velocity (r ≥ -0.90) except for the 0 to 20-m split time, where a significantly large negative correlation was found (r = -0.57). The faster group had a significantly higher maximum velocity and τ (p < 0.001), and no significant difference was found for vLoss (p = 0.085). CONCLUSION: Coaches and researchers are encouraged to utilize the 4 split time method proposed in the current study to assess several key race variables that describe a sprinter's performance capacities, which can be subsequently used to further inform training.

Sprint start performance: the potential influence of triceps surae electromechanical delay.

In the sprint start, a defined sequence of distinct response delays occurs before the athlete produces a movement response. Excitation of lower limb muscles occurs prior to force production against the blocks, culminating in a movement response. The time delay between muscle excitation and movement, electromechanical delay (EMD), is considered to influence sprint start response time (SSRT). This study examined the delay in sprint start performance from EMD of the triceps surae muscle and examined whether certain sprinters gain an advantage in SSRT. Nineteen experienced sprinters performed sprint starts from blocks, with SSRT measured by an International Association of Athletics Federations (IAAF)-approved starting block system. EMD times were detected during a heel-lift experiment. Using revised SSRT limits, based on concerns over the validity of the IAAF 100 ms false start limit, EMD produced a significant moderate correlation with SSRT (r = 0.572, p = 0.011). Regression analysis determined that together, EMD and signal processing time (the delay between the auditory signal and muscle excitation) accounted for 37% of the variance in SSRT. Initial results suggest EMD is part of the response time process and that certain athletes may gain a performance advantage due to reduced EMD.

Epidemiology of Shoulder Injuries in Schoolboy Rugby Union in Ireland.

BACKGROUND: The shoulder has been reported as a frequent location of injury in adult professional and amateur rugby, with match injury incidence rates ranging from 1.8 to 3 per 1000 player-hours (h). An increased understanding of the incidence and mechanism of shoulder injuries in school rugby players is vital to establish effective injury preventive strategies and advise on appropriate rehabilitation. PURPOSE: To describe the incidence, nature, and severity of shoulder injuries in schoolboy rugby in Ireland. STUDY DESIGN: Descriptive epidemiology study. METHODS: Injury surveillance was carried out for Senior Cup teams across two seasons (N = 665 players aged 17-19 years) in Ireland from 2018 to 2020. Match and training injury data were recorded using an online system by trained nominated injury recorders. Match exposure was also recorded. RESULTS: Shoulder match injury incidence was 12.2 per 1000 h (95% CI, 9.1-16.2), with a mean severity of 47 days' time loss and an overall burden of 573 days per 1000 h. In total, 47 match and 5 training shoulder injuries were recorded. The most common injuries were shoulder dislocations/subluxations (34%), followed by acromioclavicular joint sprains (30%). Shoulder dislocations/subluxations represented the most burdensome injury (280 days per 1000 h). The tackle accounted for the majority (81%) of shoulder injuries. Forwards sustained a significantly higher incidence of shoulder injuries (8.3/1000 h) in comparison with backs (3.9/1000 h), with a rate ratio of 2.13 (95% CI, 1.15-3.94; P = .015). CONCLUSION: We found a notably higher injury incidence rate in schoolboy rugby as compared with the adult amateur and professional game. Shoulder injuries were responsible for more days lost than any other injury, and shoulder dislocations were the most severe. This is of particular concern so early in a player's career and warrants further investigation into potential risk factors and mechanisms associated with shoulder injuries in school-age players.

Effects of Plyometric Vs. Combined Plyometric Training on Vertical Jump Biomechanics in Female Basketball Players.

The purpose of this study was to assess and compare the effects of plyometric training and combined training programs on vertical jump kinematics and kinetics of female basketball players. Thirty-six female basketball players were included in the study and further divided into three groups: plyometric training, n = 11; combined training n =13; and a control group, n =12. Combined training comprised full squat exercise with low resistance (50-65% 1RM) and low volume (3-6 repetitions/set) combined with repeated jumps. Plyometric training included drop jumps and repeated jumps. Both training methods showed a moderate increase in jump performance, although combined training achieved substantially higher values than plyometric training alone. After plyometric training, the vertical velocity and displacement of the center of mass of the countermovement jump increased, while force variables decreased. Combined training increased power, vertical velocity and displacement of the center of mass, but force variables remained unchanged. Both training methods improved jump height, velocity and displacement of the center of mass. Combined training maintained force measures while plyometric training decreased them. These results indicate that combined training might provide better outcomes on jump performance than plyometric training alone. It also appears important to measure biomechanical variables to appropriately interpret the effects of different training methods.

Injury Trends in Irish Amateur Rugby: An Epidemiological Comparison of Men and Women.

BACKGROUND: Rugby union is a physically demanding sport that carries an inherent risk of injury. Despite being a popular and widely played team sport, little is known about injuries occurring across the male and female amateur game. PURPOSE: To establish and compare injury incidence, nature, and severity in male and female Irish amateur rugby union. STUDY DESIGN: Prospective cohort study. LEVEL OF EVIDENCE: Level 3. METHODS: Data were collected prospectively from 25 male teams (959 players) and 8 female teams (234 players) over 2 full seasons. Both time-loss (24-hour time-loss injury definition) and non-time-loss match injury reports were collected, alongside match exposure data. RESULTS: Time-loss match injury incidence rates were 49.1/1000 and 35.6/1000 player-hours for male and female players, respectively. Concussion and ankle ligament sprains were the most common diagnoses for male (5.6/1000 and 4.4/1000 player-hours, respectively) and female players (5.5/1000 and 3.9/1000 player-hours, respectively). Anterior cruciate ligament injuries presented the highest injury burden for male and female players with 200.3 and 307.2 days of absence per 1000 player-hours, respectively. In female players, 83% of noncontact injuries occurred in the fourth quarter of match play. CONCLUSION: While female players had a lower overall injury incidence rate compared with male players, concussion and ankle ligament injuries were the most common injuries in both cohorts. In female players, a high rate of noncontact injuries in the second half points to the need for strength and conditioning training programs to reduce fatigue-related injuries. CLINICAL RELEVANCE: Establishing the incidence and burden of rugby-related injuries is an essential step in minimizing injury risk. This epidemiological information will aid the development of future reduction strategies, including education and coaching strategies and strength and conditioning programs, informed by the most common injuries observed and the mechanism of injury.

Onset detection in surface electromyographic signals across isometric explosive and ramped contractions: a comparison of computer-based methods.

Objective. Accurate identification of surface electromyography (EMG) muscle onset is vital when examining short temporal parameters such as electromechanical delay. The visual method is considered the 'gold standard' in onset detection. Automatic detection methods are commonly employed to increase objectivity and reduce analysis time, but it is unclear if they are sensitive enough to accurately detect EMG onset when relating them to short-duration motor events.Approach. This study aimed to determine: (1) if automatic detection methods could be used interchangeably with visual methods in detecting EMG onsets (2) if the Teager-Kaiser energy operator (TKEO) as a conditioning step would improve the accuracy of popular EMG onset detection methods. The accuracy of three automatic onset detection methods: approximated generalized likelihood ratio (AGLR), TKEO, and threshold-based method were examined against the visual method. EMG signals from fast, explosive, and slow, ramped isometric plantarflexor contractions were evaluated using each technique.Main results. For fast, explosive contractions, the TKEO was the best-performing automatic detection method, with a low bias level (4.7 ± 5.6 ms) and excellent intraclass correlation coefficient (ICC) of 0.993, however with wide limits of agreement (LoA) (-6.2 to +15.7 ms). For slow, ramped contractions, the AGLR with TKEO conditioning was the best-performing automatic detection method with the smallest bias (11.3 ± 32.9 ms) and excellent ICC (0.983) but produced wide LoA (-53.2 to +75.8 ms). For visual detection, the inclusion of TKEO conditioning improved inter-rater and intra-rater reliability across contraction types compared with visual detection without TKEO conditioning.Significance. In conclusion, the examined automatic detection methods are not sensitive enough to be applied when relating EMG onset to a motor event of short duration. To attain the accuracy needed, visual detection is recommended. The inclusion of TKEO as a conditioning step before visual detection of EMG onsets is recommended to improve visual detection reliability.

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.