Content uploaded by Lawrence L Spriet
Author content
All content in this area was uploaded by Lawrence L Spriet on Apr 11, 2018
Content may be subject to copyright.
A preview of the PDF is not available
Moderate Load Resisted Sprints Do Not Improve Subsequent Sprint Performance in Varsity-Level Sprinters
Abstract and Figures
Resisted sprint training (RST) is commonly used for performance enhancement in athletics and team sports to develop acceleration ability. Evidence suggests that RST may be effective as a short-term intervention to improve successive sprints. While these improvements have been measured in team sport athletes, limited research has considered the acute effects of RST training in sprint-trained athletes. Therefore, the aim of the current study was to determine if performing RST with varsity level sprinters using sled-equivalent resistive loads of ∼45% body mass results in a potentiation effect, leading to improvements in subsequent maximal sprint performance over 0-5 m and 0-20 m. Competitive sprinters (n=20), were randomly assigned to perform a pre/post maximal 20 m sprint separated by either 3 resisted (RST group) or un-resisted (URS group) sprints. The RST or URS protocol was performed on four occasions separated by at least 7 days. No significant differences were observed between the RST and URS groups comparing changes in sprint times over 0-5 m (URS Δ = <0.01 s ± 0.03 s, RST Δ = <0.01 s ± 0.03 s) and 0-20 m (URS Δ = 0.013 s ± 0.04 s, RST Δ = <0.01 s ± 0.04 s). We conclude that resisted sprints using sled equivalent loads of 45% body mass are ineffective at inducing a potentiating effect on subsequent sprint performance in varsity level sprinters. In this population of trained athletes, greater loads may be necessary to induce a potentiating effect.
Figures - uploaded by Lawrence L Spriet
Author content
All figure content in this area was uploaded by Lawrence L Spriet
Content may be subject to copyright.
... However, the current findings on RST and AST on PAPE are inconsistent. Some studies have found acute enhancement in sprint performance because of RST and AST (31,43,44,54,(67)(68)(69)81,83,84), while others have found no effect (19,32,35,49,(72)(73)(74)79) or even impairments (17,19,25,67). ...
... Because PAPE is influenced by a balance of potentiation and fatigue (5,61), there may be an optimal interval for RST loading: lighter loads may not sufficiently induce PAPE, while heavier loads may cause fatigue. Nevertheless, both lighter and heavier loads in RST have shown inconsistent results for PAPE (17,35,49,67,69,72,83). Similarly, Gallego et al. (13) recommended that the maximum velocity in AST should not exceed 110%, but recent studies showed inconsistent results of different AST loads on PAPE (32,35,43,54,68,74). ...
... This total comprises 21 RST studies and 6 AST studies. Corresponding data for 2 studies with missing information were provided by the authors (72,87). The 23 included studies used randomized crossover (n 5 16), parallel (n 5 2), and pre-post-test trail designs (n 5 5). ...
The aim of the meta-analysis was to determine the acute effects of resisted (RST), assisted (AST), and unresisted (UST) sprint training on sprint performance and to identify the optimal training protocol. A computerized search was conducted in five databases, resulting in the inclusion of 23 studies and 395 participants. The findings indicated that RST acutely improved sprint performance (effect size [ES] -0.20; p < 0.05), while UST (ES = -0.03) and AST (ES = -0.18) did not produce significant improvements (p > 0.05). Subgroup analyses revealed that RST load as a percentage of body mass (%BM) showed the greatest improvement with heavy loads (50-75% BM, ES = -0.40) compared to light (0-19% BM, ES = -0.22), moderate (20-49% BM, ES = -0.21), and very heavy (>75% BM, ES = 0.10) loads. Further analyses indicated that sled pushing (ES = -0.60) was more effective than sled pulling (ES = -0.34) under heavy load RST conditions. Nonlinear meta-regression results demonstrated that sprint performance improvement exhibited an inverted-U relationship with RST load. Additionally, heavy load RST and moderate load AST did not disrupt subsequent sprinting technique. In conclusion, only RST acutely improved subsequent sprint performance, whereas AST and UST did not. For optimal results with RST, it is recommended to use one set of heavy loads (50-75% BM) for sled pushing over a distance of 15-20 meters, followed by a rest period of 4-8 minutes before performing 0-30 meters of UST.
... The measurement accuracy of the 1080 Sprint compared to a radar device (Stalker Pro II) has been assessed during 30 m sprints with highly trained sprinters. 17 However, minimal information was reported regarding the methodological approach, statistical analysis, and findings. The coefficients of variation were reported as 5.11% for 0-10 m time, 4.32% for 10-20 m time, and 1.51% for 20-30 m time but no information was provided regarding the between-device measurement bias and variation values, the device measurement mean and standard deviation values, or other derived metrics such as those used in force-velocity profiling. ...
... The coefficients of variation were reported as 5.11% for 0-10 m time, 4.32% for 10-20 m time, and 1.51% for 20-30 m time but no information was provided regarding the between-device measurement bias and variation values, the device measurement mean and standard deviation values, or other derived metrics such as those used in force-velocity profiling. 17 Thus, minimal information is currently available regarding the measurement accuracy of the 1080 Sprint, particularly for use in force-velocity profiling. ...
... Considering the recent research interest in the 1080 Sprint as a training tool [17][18][19][20][21][22] and measurement device 3 and given its increasing use by coaches and sport scientists, it seems prudent to establish the agreement between data calculated from the 1080 Sprint and an alternative technology already widely used in practice, a radar device. More specifically, it is of interest to understand if measures collected with one device can be compared to measures collected by the other device in situations where athletes may train in facilities which have different devices or in a facility which has both devices. ...
This study established the magnitude of systematic bias and random error of horizontal force-velocity (F-v) profile variables obtained from a 1080 Sprint compared to that obtained from a Stalker ATS II radar device. Twenty high-school athletes from an American football training group completed a 30 m sprint while the two devices simultaneously measured velocity-time data. The velocity-time data were modelled by an exponential equation fitting process and then used to calculate individual F-v profiles and related variables (theoretical maximum velocity, theoretical maximum horizontal force, slope of the linear F-v profile, peak power, time constant tau, and horizontal maximal velocity). The devices were compared by determining the systematic bias and the 95% limits of agreement (random error) for all variables, both of which were expressed as percentages of the mean radar value. All bias values were within 6.32%, with the 1080 Sprint reporting higher values for tau, horizontal maximal velocity, and theoretical maximum velocity. Random error was lowest for velocity-based variables but exceeded 7% for all others, with slope of the F-v profile being greatest at ±12.3%. These results provide practitioners with the information necessary to determine if the agreement between the devices and the magnitude of random error is acceptable within the context of their specific application.
... Unsurprisingly, therefore, the potentiating effects of acute RSS on subsequent sprint performance has been the subject of several recent studies, with both no change (9,34,36,39) and improvement (24,40,43,44) in URS performance being reported. ...
... The equivocal results may be attributed to the many methodological differences that exist in the application of RSS as a CA including the athletic background and training status of the population studied, configuration of the CA stimulus (e.g., number of repetitions and distance of RSS, intersprint rest), the post CA to retest time interval, and the intensity of the CA (9,24,34,36,39,40,43,44). The latter is principally determined by the sled load of the RSS. ...
... However, the use of %BM to prescribe a RSS sled load is not sensitive to individual athletic characteristics, and even a standardized %BM can produce large interindividual variability in % V dec (8) and relative intensity of the stimulus (31). To date, investigation of PAPE via RSS have generally prescribed the RSS load using %BM (i.e., 10, 20, and 30%BM (34); 25-30%BM (39,44); 45-50%BM (24,36); 75 and 150%BM (43)) with only 2 studies to date having employed %V dec as the method RSS prescription (9,40). Several authors have therefore suggested that further research on the potential PAPE of RSS-based CA should be based on %V dec methods of load prescription (9,40,43). ...
The effect of resisted sled sprinting (RSS) on postactivation performance enhancement (PAPE) was investigated in team field sport athletes (n 5 28; m and female, 15 and 13; age, 22.1 6 2.5 years; height, 1.77 6 0.11 m; body mass [BM], 75.1 6 16.4 kg). After a standardized warm-up, unresisted sprint (URS) performance was measured over 10-and 20-m (PRE) followed by a conditioning activity (CA) consisting of 3 3 20 m RSS. Unresisted sprint performance was then measured again at 30 seconds and 4, 8, 12, 16, 20, and 24 minutes after CA. The effect of heavy (H-RSS) or very heavy (VH-RSS) sled loads were compared during 2 separate visits using a randomized crossover design. Heavy-resisted sled sprinting and VH-RSS loads corresponded to a velocity decrement (V dec) of 17.3 6 3.6% V dec (20.0 6 2.3%BM) and 52.9 6 3.8%V dec (64.3 6 7.0%BM), respectively. Unresisted sprint performance after CA was slower than PRE over 10-and 20-m (both p , 0.001 for time). The decline in URS performance over 20-m was greater in VH-RSS (time 3 sled load interaction, p 5 0.033). However, after extraction of the fastest sprint times after CA, the fastest sprint time for 10-m improved after H-RSS by 0.026 (0.001, 0.050) seconds (p 5 0.040; d 5 0.21) but not after VH-RSS (p 5 0.054; d 5 0.14). The fastest sprint times for 20-m were similar to PRE after H-RSS and VH-RSS. No sex-specific differences were observed. Given the high intersubject variability in the magnitude of improvement, and for the time point at which the fastest sprint occurred, there remains questionable practical value to an RSS-based CA as a means to induce a PAPE for URS performance.
... The vast majority of studies have focused on chronic adaptations to resisted sprint training (West et al., 2013;Petrakos et al., 2016;Alcaraz et al., 2018;Gil et al., 2018), and only a few have assessed the acute effects of resisted sprints on subsequent sprint performance (Whelan et al., 2014;Winwood et al., 2016;Seitz et al., 2017;van den Tillaar and von Heimburg, 2017;Wong et al., 2017;Mangine et al., 2018;van den Tillaar et al., 2018;Thompson et al., 2021). In addition, those that were conducted analyzed the effectiveness of a single or two very high loads (75-150% of body mass) on inducing the potentiating effect (Winwood et al., 2016;Seitz et al., 2017). ...
... The study by Mangine et al. (2018) found no improvement in the 20-m sprint time after resisted sprints with a load equal to 5% of body mass. Moreover, Thompson et al. (2021) compared the potentiation effect of resisted sprints with a load of ∼16% of body mass (∼45% body mass sled equivalent load, as the cable device, is not dependent on sprint surface coefficient of friction) with unresisted sprints on subsequent 5-and 20m sprint performance in varsity-level sprinters. The authors found that resisted and unresisted sprints are ineffective in inducing acute sprint performance enhancement. ...
... The authors found that resisted and unresisted sprints are ineffective in inducing acute sprint performance enhancement. Nevertheless, the authors examined the activation effectiveness of a single load and 3-min (Mangine et al., 2018) or 5-min (Thompson et al., 2021) rest intervals between sprints. Our study showed the greatest improvement in sprint evaluated at 20 m, after applying a load equal to 10% of body mass (∼2.5% decrease in sprint time). ...
Considering the effectiveness of resisted sprint training, and the acute enhancement of sprinting performance through locomotor post-activation performance enhancement, the main objective of the research was to determine the acute effects of resisted activation with loads of 5, 10, and 15% body mass on sprint and flying start sprint performance in elite female sprinters using resisted drag technology system. Ten elite female sprinters (age: 23.2 ± 5.4 years, body mass: 54.2 ± 6.1 kg, height: 167.4 ± 7.3 cm, personal best for 100 m: 12.05 ± 0.56 s, and for 400 m: 53.17 ± 2.76 s) performed two unresisted 20-m sprints (from a crouched and flying start) before and after a single resisted sprint loaded with 5, 10, or 15% body mass to verify the effectiveness of the activation stimulus. Compared with pre-activation, Friedman tests showed that peak velocity increased by 1.6 ± 2.2% [effect size (ES) = 0.66], 2.3 ± 1.5% (ES = 1.33), and 0.2 ± 1% (ES = 0.09), as well as peak force by 2.8 ± 2.1% (ES = 0.49), 3.5 ± 2.3% (ES = 1), and 0.5 ± 2.4% (ES = 0.14), concomitant with a significant decreased in sprint time by −0.5 ± 1.2% (ES = −0.07), −2.5 ± 1.3% (ES = −0.64), and −1 ± 1.4% (ES = −0.36) for the 5, 10, and 15% body mass post-activation, respectively (p < 0.001; for all). Furthermore, the ANOVA showed that peak power increased by 2.9 ± 2.3% (ES = 0.61), 3.8 ± 2.2% (ES = 1.05), and 2 ± 7.1% (ES = 0.22) for the 5, 10, and 15% body mass resisted-conditioning activity, respectively, with no difference between the three conditions (p = 0.003 main effect time, no interaction). Moreover, compared with the 5 and 15% body mass trials [−1.5 ± 2% (ES = −0.44), −0.8 ± 0.8% (ES = −0.44), respectively], the ANOVA showed that flying start sprint time significantly decreased by −4.3 ± 1.1% (ES = −1.25) (p < 0.001, interaction effect) after a 10% body mass resisted-conditioning activity. The results of this study indicated that resisted sprints acutely enhance sprint performance; however, their effectiveness depends on the applied load. A single resisted sprint using 10% body mass is effective at inducing a potentiating effect on subsequent 20-m flying start sprint performance in elite female sprinters. Therefore, keeping in mind the optimal load, it is recommended to perform resisted sprints as a conditioning activation when seeking to acutely enhance 20-m flying start sprint performance in these athletes.
... One such example is Kinexon Perform GPS Pro (Kinexon Precision Technologies, Munich, Germany) which is supposed to offer increased accuracy compared to previous versions due to changes in the sensor hardware (Schmidt et al. 2022). Lastly, new technologies such as magnetic timing systems (e.g., Freelap, Freelap USA, Pleasanton, USA; SmarTracks, Humotion, Münster, Germany) are entering the market and are being used in both sports practice and research (Machulik et al. 2020;Thompson et al. 2021;Hallam et al. 2022) while their validity for MSS assessments is yet to be established. ...
... However, the reason for this remains unclear and needs further investigation. In addition, Thompson et al. (2021) compared another commercially available magnetic timing system (Freelap) to a robotic sprint resistance device. While the authors reported very large correlations (Pearson's r), no data about the magnitude of the mean and individual differences between the devices were provided (i.e., LoA), making comparisons to the present study impossible. ...
This study aimed to investigate the criterion validity of commonly used devices to assess maximalsprinting speed (MSS) in soccer. Thirty elite youth soccer players completed three trials of a 30-m sprinttest to assess MSS. All sprints were simultaneously captured via a radar gun (Stalker ATS II), timing gates (Smartspeed Pro, Fusion Sport), a magnetic timing system (Humotion SmarTracks) and a global navigation satellite system (GNSS) (Kinexon Perform GPS Pro). The radar gun and the GNSS recorded sprintingspeed continuously, while the fastest 5-m split during the 30-m sprint was used for the timing gates andthe magnetic system. The best trial of the radar gun (i.e. criterion measure) and corresponding values ofthe other devices were analyzed. Equivalence testing was performed to assess the statistical equivalenceof MSS between the radar gun and the three other devices against a difference value of ± 0.36 km/h andBland & Altman’s 95% limits of agreement (LoA) were computed to investigate the agreement betweenMSS results. Differences between GNSS versus radar gun suggested a lack of systematic bias (−0.01 km/h,95% confidence interval [CI] −0.15 to 0.15 km/h), whereas timing gates-based MSS assessments wereprone to larger uncertainty compared to the criterion method (−0.19 km/h, 95% CI: −0.37 to 0.00 km/h)given the pre-defined region of equivalence. The magnetic system (−0.54 km/h; −0.71 to −0.37 km/h)overestimated MSS compared to the radar gun with mean differences being non-equivalent. Based onthe practically important difference bounds of ± 0.36 km/h, the width of the 95% LoA was broad enoughto suggest a lack of reasonable agreement for MSS assessment regardless of device of interest (GNSS:−0.79 to 0.78 km/h, timing gates: −0.79 to 1.16 km/h, magnetic system: −0.24 to 1.32 km/h). While ourresults suggested a lack of systematic bias for the investigated GNSS and the timing gates whencompared against the radar gun for MSS assessment over 30 m in elite youth soccer players on a teamlevel, the width of the 95% LoAs did not indicate reasonable measurement interchangeability on anindividual level. Based on the present results, we do not recommend using the magnetic system for bothgroup and individual analyses in this population.
... Subsequently, Yoshimoto et al 18 found similar results after using 3 sets of 10 consecutive "mini-hurdle drills" with collegiate sprinters (ie, on average, sprinters exhibited a decrease of −1.6% in the 60-m sprint time). On the other hand, several investigations conducted with competitive sprinters at various competitive levels (ie, regional, national, and international) [19][20][21] did not find any significant improvement in sprint performance across a range of distances (from 5 to 40 m) following the utilization of different types of exercises and motor tasks as CAs (eg, isometric contractions, resisted sprints, and reactive hops). Therefore, even for these highly specialized athletes with a clear performance indicator (ie, sprinting time or sprinting speed), there is still no consensus on which strategy to use or whether there is in fact a strategy capable of acutely enhancing their sprint performance. ...
... As a result, 40 studies were evaluated for eligibility, and based on the inclusion and exclusion criteria (see Figure 1), 14 studies were finally included in the meta-analysis. [17][18][19][20][21][29][30][31][32][33][34][35][36][37] Overall, the risk of bias among the analyzed studies was considered "low," with 13 demonstrating a "low risk of bias" and 1 presenting "some concerns" (see Figure 2). The quality of the studies, as assessed by the Physiotherapy Evidence Database scale, was high, with a mean score of 6.9 (0.3) out of 10 points (see Table 1). ...
Purpose : Postactivation performance enhancement (PAPE), which refers to the phenomena associated with the attainment of enhanced performance in sport-specific tasks after a conditioning activity, is an important objective of warming-up practices in many sports. This is even more relevant for sprinters, as potential increases in sprinting speed will directly influence their competitive results. This systematic review with meta-analysis evaluated the effects of different PAPE protocols (ie, using plyometrics, strength-power exercises, and resisted/assisted sprints) on the sprinting performance (ie, sprint time or sprint speed) of competitive sprinters. Methods : Initially, 1205 records published until last December 18 were identified, using the following databases: PubMed/MEDLINE, Scopus, and Clarivate Web of Science. After removing duplicates and screening titles and abstracts, 14 high-quality studies met the inclusion criteria for the meta-analysis. Results : Overall, there were no significant changes in sprint performance after implementing various types of conditioning activities (standardized mean difference [SMD] = 0.16 [95% CI, −0.02 to 0.33]; Z = 1.78; P = .08; I ² = 0%). In addition, when comparing prechanges and postchanges between experimental, control, and other conditions, no significant differences were found in sprint speed or time across all studies (SMD = 0.09 [95% CI, −0.10 to 0.28]; Z = 0.92; P = .36; I = 0%). Conclusions : Results revealed that different types of conditioning activities may not be capable of acutely enhancing the sprint speed of competitive sprinters. This aligns with previous observations indicating that sprinting is a highly stable physical capacity, a phenomenon that is even more consistent among elite sprinters. Coaches and sport scientists should collaborate to develop more efficient PAPE protocols for these highly specialized athletes, with special attention to study design and individualization, while considering their effects on acceleration versus top speed.
... In a similar study using international and national level male and female sprinters, Matusiński et al. (2022) reported significant decreases in 10 and 50 m sprint time following 3 x 30 m resisted sprints at 10% body mass compared to baseline (male 10 m and 50 m, p = 0.002, η 2 = 0.25 and p = 0.001, η 2 = 0.45; female 10 m and 50 m, p = 0.002, η 2 = 0.20 and p = 0.001, η 2 = 0.29). Using the same equipment to provide the sprint resistance as the two previous studies (1080 Sprint device), Thompson et al. (2021) showed no significant differences in sprint performance over 20 m. However, the varsity level sprinters were exposed to a load of ~45% of body mass and performed three resisted sprints prior to the final unresisted sprint. ...
... Overall, there were higher occurrences of fatiguing events compared to PAPE events across reactive strength index and stride length, whilst the reverse was the case for contact time, velocity and step rate. A heavier preconditioning load of ~45% body mass was used by Thompson et al. (2021) in their study with varsity-level sprinters. A single unresisted sprint, followed by three resisted sprints showed no performance enhancement in a final single 20 m sprint. ...
Sprint performance and therefore sprint training play important roles in a range of sports and numerous methods to enhance sprint performance have been proposed. One such method is resisted sprinting, whereby a predetermined load (% body mass) or a load which elicits a reduction in sprint velocity, is towed over a prescribed distance. Resisted sprint training can be implemented chronically or acutely. The latter is used to elicit a performance enhancement via post-activation potentiation whereby a superior performance may be achieved when the activity is preceded by a specific stimulus, usually as part of the warm up. The purpose of this study was to determine if a post-activation performance enhancement (PAPE) could be achieved following an acute resisted sprint at two different decreases in sprint velocity using novel resisted sprint equipment (Run Rocket). Eleven healthy male, recreationally trained volunteers (age 23.4 ± 1.9 years, height 180.5 ± 3.5 cm, body mass 86.4 ± 14.5 kg) participated in the study. A maximal 15 m baseline body mass only sprint was performed on the initial visit to ascertain 5 and 15 m sprint time. Participants visited a further two times which consisted of a pre-conditioning resisted sprint activity using the Run Rocket at two different resistance settings in a randomised counter-balanced design. A repeated measures analysis of variance (rmANOVA) showed no significant differences in sprint time, velocity or acceleration between the three conditions (p> 0.05). However, when assessing individuals by the smallest worthwhile change, some participants may have decreased their sprint time. Therefore, the use of resisted sprints did not elicit a post-activation performance enhancement in recreationally trained individuals and may not be beneficial for augmenting acute performance in this population. Individual responses to this type of training may vary and should be a consideration for strength coaches.
... Hence, the mean variations in sprint times described here (from -2% to +4.2%) can, literally, represent real differences between medalists and nonmedalists in international tournaments, including sprinters not qualified for the finals (13). It is crucial to emphasize that enhancements in sprint performance are also reduced or even non-existent in training studies involving sprinters, for both acute and chronic interventions (3,28). Thompson et al. (28) showed that sled towing with 45% BM is ineffective to induce a potentiating effect in national level sprinters. ...
We assessed the changes in sprint, jump, and power parameters across the annual training cycle and tested the longitudinal correlations among these variables in top-level sprinters. Thirteen sprinters training with four different Olympic sprint coaches were sequentially assessed over 14 months, consecutive training camps. Performance tests were conducted as follows: standing long jump, squat and countermovement jumps, 10-and 60-m sprint time, and maximum power output in the half-squat, jump-squat, and hip-thrust exercises. The competitive results of the sprinters throughout the study period were also recorded and analyzed. A repeated measures analysis of variance was used to compare the physical measurements between different testing sessions. A Pearson product-moment correlation was applied to examine the longitudinal relationships between changes in speed-and power-related parameters. Percentage change was computed and compared to CV values to determine whether changes in performance metrics were higher than the test variance, thus providing an indication of whether true changes occurred on an individual basis. Overall, sprinters did not exhibit significant changes in sprint speed, jumping ability, and power output. Additionally, variations in competitive times (i.e., 100-m races) followed a similar pattern, within an average range of ±1.36%, for both male and female sprinters. As expected, top-level sprinters presented only small variations in physical and competitive performance over time. Nevertheless, the use of an individual statistical technique (i.e., true changes calculation) revealed that these non-significant increases or decreases may represent meaningful changes in their competitive potential.
... The device simultaneously records horizontal velocity, power, force, distances, and time. Absolute resistance was converted to relative robotic resistance (0.35 conversion coefficient provided by the manufacturer not considering sprint surface coefficient of friction) (4,23), with distance modeled based on pilot testing as follows: 40 m at 3 kg; 30 m at 25 and 50% of equipped BM and 20 m at 75% of equipped BM. Recently, Thompson et al. (23) compared 0-10 m, 10-20 m, and 20-30 m sprint times recorded using both devices and found high-to-very high positive correlations (i.e., r ranging from 0.87 to 0.99). ...
Perez, J, Guilhem, G, and Brocherie, F. Ice hockey forward skating force-velocity profiling using single unloaded vs. multiple loaded methods. J Strength Cond Res XX(X): 000-000, 2021-This study aimed to compare skating force-velocity relationships determined throughout sprints performed against various loaded conditions or inferred from movement kinetics measured during a single unloaded sprint. Ten female ice hockey players performed one unloaded maximal skating sprint test measured with a radar gun followed by 4 resisted skating sprints against a robotic horizontal resistance with progressive loads in reference to equipped body mass (BM): 3 kg (robotic resistance), 25, 50, and 75% of equipped BM. Maximal theoretical force (F0), velocity (V0), power (Pmax), optimal velocity (Vopt) condition for producing maximal power, and slope of the linear force-velocity relationship (SFV) were determined from each method and compared using a paired sample t-test, absolute mean bias (±95% confidence intervals), Pearson correlations, and typical error of the estimate in standardized units (effect size [ES]). Statistical significance was set at p < 0.05. No statistical difference was found for all mechanical variables determined from the 2 methods (p ranging 0.09-0.59). Although exhibiting positive correlations ranging from moderate (r = 0.50 for SFV) to high (r ranging from 0.71 to 0.84 for F0, V0, Vopt, and Pmax) between methods, all variables exhibited large levels of error between approaches (ES ranging 0.66-1.71). Multiple loaded and single unloaded methods were comparable with determine force-velocity relationships during forward on-ice skating sprint. The low-cost fatigue-free unloaded method suggests it could be used in constrained contexts (i.e., congested schedule and low available time) or for a simple force-velocity profiling. Inversely, multiple loaded methods would be more appropriate to evaluate and individualize training for skilled ice hockey players accustomed to resistive skating sprint.
Rakovic, E, Paulsen, G, Helland, C, Haugen, T, and Eriksrud, O. Validity and reliability of a motorized sprint resistance device. J Strength Cond Res 36(8): 2335-2338, 2022-An increasing number of sprint-related studies have used motorized devices to provide resistance while sprinting. The aim of this study was to establish within-session reliability and criterion validity of sprint times obtained from a motorized resistance device. Seventeen elite, female, handball players (22.9 ± 3.0 years; 176.5 ± 6.5 cm; 72.7 ± 5.5 kg; training volume 9.3 ± 0.7 hours per week) performed two 30-m sprints under 3 different resistance loading conditions (50, 80 and 110 N). Sprint times (t0-5m, t5-10m, t10-15m, t15-20m, t20-30m, and t0-30m) were assessed simultaneously by a 1080 Sprint motorized resistance device and a postprocessing timing system. The results showed that 1080 Sprint timing was equivalent to the postprocessing timing system within the limits of precision (±0.01 seconds). A systematic bias of approximately 0.34 ± 0.01 seconds was observed for t0-5m caused by different athlete location and velocity at triggering point between the systems. Coefficient of variation was approximately 2% for t0-5 and approximately 1% for the other time intervals, although standard error of measurement ranged from 0.01 to 0.05 seconds, depending on distance and phase of sprint. Intraclass correlation ranged from 0.86 to 0.95. In conclusion, the present study shows that the 1080 Sprint is valid and reliable for sprint performance monitoring purposes.
Objectives: The purpose of this study was to assess the practical use of heavy sled towing and its acute implications on subsequent sprint acceleration performance.
Design and Methods: Eight healthy male varsity team sport athletes (age: 21.8 ± 1.8years, height: 185.5 ± 5.0cm, weight: 88.8 ± 15.7kg, 15m sprint time: 2.66 ± 0.13s) performed sprints under three separate weighted sled towing conditions in a randomized order. Each condition consisted of one baseline unweighted sprint (4-min pre), the sled towing sprint protocol: (1) 1 × 50% body mass, (2) 2 × 50% body mass, (3) 3 × 50% body mass (multiple sprints interspersed with 90s recovery), and 3 post-testing unweighted sprints thereafter (4, 8, 12-min post). All sprints were conducted over a 15m distance.
Results: Significantly faster sprint times for the 3 × sled towing protocol were identified following 8-min of rest (p = 0.025, d = 0.46, 2.64 ± 0.15s to 2.57 ± 0.17s). When individual best sprint times were analyzed against baseline data, significantly faster sprint times were identified following both 1 × (p = 0.007, d = 0.69, 2.69 ± 0.07s to 2.64 ± 0.07s) and 3 × (p = 0.001, d = 0.62, 2.64 ± 0.15s to 2.55 ± 0.14s) sled towing protocols. Within the 3 × condition, all athletes achieved fastest sprint times following 8-12 min of rest.
Conclusions: The findings from the present study indicate that a repeated bout of sled towing (3 × 50% body mass) leads to the enhancement in subsequent sprint acceleration performance, following adequate, and individualized recovery periods.
Purpose:
To ascertain whether force-velocity-power relationships could be compiled from a battery of sled-resisted overground sprints and to clarify and compare the optimal loading conditions for maximizing power production for different athlete cohorts.
Methods:
Recreational mixed-sport athletes (n = 12) and sprinters (n = 15) performed multiple trials of maximal sprints unloaded and towing a selection of sled masses (20-120% body mass [BM]). Velocity data were collected by sports radar, and kinetics at peak velocity were quantified using friction coefficients and aerodynamic drag. Individual force-velocity and power-velocity relationships were generated using linear and quadratic relationships, respectively. Mechanical and optimal loading variables were subsequently calculated and test-retest reliability assessed.
Results:
Individual force-velocity and power-velocity relationships were accurately fitted with regression models (R2> .977, P < .001) and were reliable (ES = 0.05-0.50, ICC = .73-.97, CV = 1.0-5.4%). The normal loading that maximized peak power was 78% ± 6% and 82% ± 8% of BM, representing a resistance of 3.37 and 3.62 N/kg at 4.19 ± 0.19 and 4.90 ± 0.18 m/s (recreational athletes and sprinters, respectively). Optimal force and normal load did not clearly differentiate between cohorts, although sprinters developed greater maximal power (17.2-26.5%, ES = 0.97-2.13, P < .02) at much greater velocities (16.9%, ES = 3.73, P < .001).
Conclusions:
Mechanical relationships can be accurately profiled using common sled-training equipment. Notably, the optimal loading conditions determined in this study (69-96% of BM, dependent on friction conditions) represent much greater resistance than current guidelines (~7-20% of BM). This method has potential value in quantifying individualized training parameters for optimized development of horizontal power.
Understanding the impact of friction in sled sprinting allows the quantification of kinetic outputs and the effective loading experienced by the athlete. This study assessed changes in the coefficient of friction (µk) of a sled sprint-training device with changing mass and speed to provide a means of quantifying effective loading for athletes. A common sled equipped with a load cell was towed across an athletics track using a motorised winch under variable sled mass (33.1–99.6 kg) with constant speeds (0.1 and 0.3 m · s−1), and with constant sled mass (55.6 kg) and varying speeds (0.1–6.0 m · s−1). Mean force data were analysed, with five trials performed for each condition to assess the reliability of measures. Variables were determined as reliable (ICC > 0.99, CV < 4.3%), with normal-force/friction-force and speed/coefficient of friction relationships well fitted with linear (R2 = 0.994–0.995) and quadratic regressions (R2 = 0.999), respectively (P < 0.001). The linearity of composite friction values determined at two speeds, and the range in values from the quadratic fit (µk = 0.35–0.47) suggested µk and effective loading were dependent on instantaneous speed on athletics track surfaces. This research provides a proof-of-concept for the assessment of friction characteristics during sled towing, with a practical example of its application in determining effective loading and sled-sprinting kinetics. The results clarify effects of friction during sled sprinting and improve the accuracy of loading applications in practice and transparency of reporting in research.
The purpose of this study was to examine the relationships between maximal voluntary postactivation potentiation (PAP) and maximal knee extensor torque, quadriceps cross-sectional area (CSA) and volume, and type II myosin heavy chain (MHC) isoform percentage in human skeletal muscle. Thirteen resistance-trained men completed a test protocol consisting of 2 isokinetic knee extensions at 180°·s–¹ performed before and 1, 4, 7, and 10 min after the completion of 4 maximal knee extensions at 60°·s–¹ (i.e., a conditioning activity (CA)). Magnetic resonance imaging and muscle microbiopsy procedures were completed on separate days to assess quadriceps CSA and volume and MHC isoform content. Maximal voluntary PAP response was assessed as the ratio of the highest knee extensor torques measured before and after the CA. There were large to very large correlations between maximal voluntary PAP response and maximal knee extensor torque (r = 0.62) and quadriceps CSA (r = 0.68) and volume (r = 0.63). Nonetheless, these correlations were not statistically significant after adjusting for the influence of type II MHC percentage using partial correlation analysis. By contrast, the strongest correlation was observed for type II MHC percentage (r = 0.77), and this correlation remained significant after adjusting for the other variables. Maximal voluntary PAP response is strongly correlated with maximal knee extensor torque and quadriceps CSA and volume, but is mostly clearly associated with the type II myosin isoform percentage in human skeletal muscle.
Recent literature supports the importance of horizontal ground reaction force (GRF) production for sprint acceleration performance. Modeling and clinical studies have shown that the hip extensors are very likely contributors to sprint acceleration performance. We experimentally tested the role of the hip extensors in horizontal GRF production during short, maximal, treadmill sprint accelerations. Torque capabilities of the knee and hip extensors and flexors were assessed using an isokinetic dynamometer in 14 males familiar with sprint running. Then, during 6-s sprints on an instrumented motorized treadmill, horizontal and vertical GRF were synchronized with electromyographic (EMG) activity of the vastus lateralis, rectus femoris, biceps femoris, and gluteus maximus averaged over the first half of support, entire support, entire swing and end-of-swing phases. No significant correlations were found between isokinetic or EMG variables and horizontal GRF. Multiple linear regression analysis showed a significant relationship (P = 0.024) between horizontal GRF and the combination of biceps femoris EMG activity during the end of the swing and the knee flexors eccentric peak torque. In conclusion, subjects who produced the greatest amount of horizontal force were both able to highly activate their hamstring muscles just before ground contact and present high eccentric hamstring peak torque capability.
The aim of this review is to investigate methodological concerns associated with sprint performance monitoring, more specifically the influence and magnitude of varying external conditions, technology and monitoring methodologies not directly related to human physiology. The combination of different starting procedures and triggering devices can cause up to very large time differences, which may be many times greater than performance changes caused by years of conditioning. Wind, altitude, temperature, barometric pressure and humidity can all combine to yield moderate time differences over short sprints. Sprint performance can also be affected by the athlete’s clothing, principally by its weight rather than its aerodynamic properties. On level surfaces, the track compliance must change dramatically before performance changes larger than typical variation can be detected. An optimal shoe bending stiffness can enhance performance by a small margin. Fully-automatic timing systems, dual-beamed photocells, laser guns and high-speed video are the most accurate tools for sprint performance monitoring. Manual timing and single-beamed photocells should be avoided over short sprint distances (10-20 m) due to large absolute errors. The validity of today’s GPS technology is satisfactory for long distances (>30 m) and maximal velocity in team sports, but multiple observations are still needed due to questionable reliability. Based on different approaches used to estimate the smallest worthwhile performance change and the typical error of sprint measures, we have provided an assessment of the usefulness of speed evaluation from 5 to 40 m. Finally, we provide statistical guidelines to accurately assess changes in individual performance; i.e., considering both the smallest worthwhile change in performance and the typical error of measurement, which can be reduced while repeating the number of trials.
Background:
Based on recent findings regarding the mechanical determinants of sprint performance, resisted sled sprint (RSS) training may provide an effective tool for the improvement of sprint acceleration and maximal velocity. However, the volume and intensity for effective RSS training in different populations is unclear.
Objectives:
The primary objective was to evaluate the effectiveness of RSS training compared with unresisted sprint (URS) training, and the differential effects of sled load on RSS training outcomes.
Data sources:
STUDY ELIGIBILITY AND APPRAISAL: A systematic review was performed primarily using PubMed and SPORTDiscus databases. Peer-reviewed studies were accepted only if the participants used a sled towing device for a longitudinal intervention of resisted sprint training, and if RSS training was the primary difference in training intervention between groups. Effect size (ES) reported using Cohen's d was presented to compare the magnitude of effect between both dependent and independent groups.
Results:
A total of 11 studies fulfilled the eligibility criteria. Sled loads were prescribed either as a percentage of body mass (%BM), a targeted reduction in velocity compared with unresisted sprint velocity (%V dec) or as an absolute load (kg). RSS training with 'light' (<10 %BM or <10 %V dec) loads provide 'small' decrements in acceleration (-1.5 %, ES = 0.50) to 'moderate' improvements in maximal sprint velocity (2.4 %, ES = 0.80) in sprint-trained individuals. 'Moderate' (10-19.9 %BM or 10-14.9 %V dec) to 'very heavy' (>30 %BM or >30 %V dec) sled loads provide 'trivial' to 'extremely large' improvements in acceleration performance (0.5-9.1 %, ES = 0.14-4.00) in strength-trained or team sport individuals. Whether RSS training is more effective than URS training in the improvement of acceleration or maximal sprint velocity remains equivocal.
Conclusions:
RSS training is a novel training method with potential for the improvement of sprint performance, but its performance benefits over URS training remain to be conclusively demonstrated. Between-study comparisons are limited primarily by discrepancies in the training status and phase of the participants, and sled load prescription. Future work is required to define the optimal load and volume for RSS depending on the specific components of sprint performance to be enhanced.
Background
Although post-activation potentiation (PAP) has been extensively examined following the completion of a conditioning activity (CA), the precise effects on subsequent jump, sprint, throw, and upper-body ballistic performances and the factors modulating these effects have yet to be determined. Moreover, weaker and stronger individuals seem to exhibit different PAP responses; however, how they respond to the different components of a strength–power–potentiation complex remains to be elucidated.
Objectives
This meta-analysis determined (1) the effect of performing a CA on subsequent jump, sprint, throw, and upper-body ballistic performances; (2) the influence of different types of CA, squat depths during the CA, rest intervals, volumes of CA, and loads during the CA on PAP; and (3) how individuals of different strength levels respond to these various strength–power–potentiation complex components.
Methods
A computerized search was conducted in ADONIS, ERIC, SPORTDiscus, EBSCOhost, Google Scholar, MEDLINE, and PubMed databases up to March 2015. The analysis comprised 47 studies and 135 groups of participants for a total of 1954 participants.
Results
The PAP effect is small for jump (effect size [ES] = 0.29), throw (ES = 0.26), and upper-body ballistic (ES = 0.23) performance activities, and moderate for sprint (ES = 0.51) performance activity. A larger PAP effect is observed among stronger individuals and those with more experience in resistance training. Plyometric (ES = 0.47) CAs induce a slightly larger PAP effect than traditional high-intensity (ES = 0.41), traditional moderate-intensity (ES = 0.19), and maximal isometric (ES = –0.09) CAs, and a greater effect after shallower (ES = 0.58) versus deeper (ES = 0.25) squat CAs, longer (ES = 0.44 and 0.49) versus shorter (ES = 0.17) recovery intervals, multiple- (ES = 0.69) versus single- (ES = 0.24) set CAs, and repetition maximum (RM) (ES = 0.51) versus sub-maximal (ES = 0.34) loads during the CA. It is noteworthy that a greater PAP effect can be realized earlier after a plyometric CA than with traditional high- and moderate-intensity CAs. Additionally, shorter recovery intervals, single-set CAs, and RM CAs are more effective at inducing PAP in stronger individuals, while weaker individuals respond better to longer recovery intervals, multiple-set CAs, and sub-maximal CAs. Finally, both weaker and stronger individuals express greater PAP after shallower squat CAs.
Conclusions
Performing a CA elicits small PAP effects for jump, throw, and upper-body ballistic performance activities, and a moderate effect for sprint performance activity. The level of potentiation is dependent on the individual’s level of strength and resistance training experience, the type of CA, the depth of the squat when this exercise is employed to elicit PAP, the rest period between the CA and subsequent performance, the number of set(s) of the CA, and the type of load used during the CA. Finally, some components of the strength–power–potentiation complex modulate the PAP response of weaker and stronger individuals in a different way.
Objectives:
The objective of this study was to examine the potentiating effects of performing a single sprint-style sled push on subsequent unresisted 20m sprint performance.
Design:
Randomized crossover design.
Methods:
Following a familiarization session, twenty rugby league players performed maximal unresisted 20m sprints before and 15s, 4, 8 and 12min after a single sled push stimulus loaded with either 75 or 125% body mass. The two sled push conditions were performed in a randomized order over a one-week period. The fastest sprint time recorded before each sled push was compared to that recorded at each time point after to determine the post-activation potentiation (PAP) effect.
Results:
After the 75% body mass sled push, sprint time was 0.26±1.03% slower at the 15s time point (effect size [ES]=0.07) but faster at the 4 (-0.95±2.00%; ES=-0.22), 8 (-1.80±1.43%; ES=-0.42) and 12 (-1.54±1.54%; ES=-0.36)min time points. Sprint time was slower at all the time points after the 125% body mass sled (1.36±2.36%-2.59±2.90%; ESs=0.34-0.64).
Conclusions:
Twenty-meter sprint performance is potentiated 4-12min following a sled push loaded with 75% body mass while it is impaired after a 125% body mass sled. These results are of great importance for coaches seeking to potentiate sprint performance with the sled push exercise.
The first sport-science-oriented and comprehensive paper on magnitude-based inferences (MBI) was published 10 y ago in the first issue of this journal. While debate continues, MBI is today well established in sport science and in other fields, particularly clinical medicine, where practical/clinical significance often takes priority over statistical significance. In this commentary, some reasons why both academics and sport scientists should abandon null-hypothesis significance testing and embrace MBI are reviewed. Apparent limitations and future areas of research are also discussed. The following arguments are presented: P values and, in turn, study conclusions are sample-size dependent, irrespective of the size of the effect; significance does not inform on magnitude of effects, yet magnitude is what matters the most; MBI allows authors to be honest with their sample size and better acknowledge trivial effects; the examination of magnitudes per se helps provide better research questions; MBI can be applied to assess changes in individuals; MBI improves data visualization; and MBI is supported by spreadsheets freely available on the Internet. Finally, recommendations to define the smallest important effect and improve the presentation of standardized effects are presented.