Improve Sprint Performance Research Articles

Influence of Strength, Sprint Running, and Combined Strength and Sprint Running Training on Short Sprint Performance in Young Adults.

The purpose of this study was to assess the degree of transference of 6 weeks of full squat vs. full squat plus sprint running training to short (ranged from 0-10 to 0-30 m) sprint running performance in non-athletes. We hypothesized that a speed-full-squat training regimen could enhance squat strength and power with simultaneous improvements in short sprint performance. 122 physically active adults (age: 20.5±2.5 years; body mass: 65.8±6.1 kg; height: 1.71±0.08 m) were randomly divided into 4 groups: full squat training (n=36), combined full squat and sprint training (n=32), speed training only (n=34) and non-training control group (n=20). Each training group completed 2 sessions per week over 6 weeks, while the control group performed only their normal physical activity. Sprint performance was improved after sprint running or full squat training alone (1.7% and 1.8% P<0.05, respectively), however larger enhancements (2.3%; P<0.01) were observed after the combined full squat plus sprint training intervention. These results suggest that in recreationally active adults, combined full squat and sprint training provides a greater stimulus for improving sprint performance than either modality alone.

Effect Of L-citrulline On Muscle Recovery After Anaerobic And Aerobic Exercise

PURPOSE: Previous research shows that acute L-citrulline (CT) supplementation improves anaerobic performance and reduces muscle soreness, suggesting it may improve muscle recovery following exercise. With a double blind crossover design, we evaluated the acute effect of CT supplementation on muscle recovery and cycling sprint and 2 mi time trial (TT) performance. METHODS: 22 college students (19.5 ± 1.3 y) completed a preliminary cycling VO2 max test (43.2 ± 10.8 ml/kg/min) and were then twice familiarized with the sprint test (4x12 s sprints at 5.5% of body mass, separated by 2.5 min of active recovery) and the TT; 48 h separated testing sessions. Approximately 5 d later and 1 hr before repeating the tests, 11 subjects consumed 6 g of CT, while the other 11 ingested 6 g of a cornstarch placebo (PT); to assess recovery, the tests were repeated 24 hr later. After a 1 wk washout, subjects repeated the tests with the other treatment. Data were analyzed with two-way repeated measures ANOVA; Bonferroni post-hoc analyses located specific differences. RESULTS: Table 1 shows mean power in watts (W) for maximum peak power (MPP), average peak power (APP), maximum mean power (MMP), and average mean power (AMP) for the sprint tests, and mean time in seconds and power (W) for the TT. CONCLUSION: Citrulline decreased aerobic performance, reducing TT power and increasing TT time relative to PT; CT did not affect anaerobic performance or muscle recovery. In contrast, 6 g or 24 kcal of cornstarch ingested 1 h before exercise improved sprint performance 24 h after a bout of similar exercise.Table: No title available.

Effect Of Adding Whole Body Vibration To Preconditioning Exercise On Sprint Performance In Well-trained Cyclists

PURPOSE: In cross-country mountain biking the start is important due to the importance of a good position when entering the single track where it is difficult to pass other cyclists. Training methods to acutely enhance sprint performance in the start of a cross-country race may be of great value for the performance. Postactivation potentiation (PAP) exercises with added whole-body vibration (WBV) have been suggested to be a potential way to acutely improve sprint performance. We have recently shown that adding WBV with a vibration frequency of 50 Hz to body-loaded half-squats improves subsequent 40 m sprint performance in soccer players (3). However, not all studies do find a significant effect of adding WBV (1, 2). The purpose of the present study is to investigate the effect of adding WBV to body-loaded half-squats, performed as preconditioning activity, on a 15-sec all-out cycle sprint in cyclists. METHODS: Eleven well-trained cyclists participated in the study (age: 18±1 years, body mass: 68.5 ± 9.5 kg, body height: 180 ± 6 cm, VO2max: 76 ± 5 ml·kg-1·min-1). All cyclists performed a familiarization session consisting of two 15 s sprints without WBV and two 15 s sprints with WBV prior to the sprints. Thereafter where two separate test sessions performed, wherein each session included a standardized warm-up followed by one of the following preconditioning exercises; 30 s of half-squats without WBV, or 30 s of half-squats with WBV at 50 Hz and a amplitude og 3 mm. A 15 s Wingate sprint was performed one minute after the preconditioning exercise (Lode Excalibur Sport, Lode B. V., Groningen, The Netherlands), with registration of peak and mean power. The test sessions were performed in a randomized order. RESULTS: Performing preconditioning exercise with WBV at 50 Hz resulted in superior peak power output compared to preconditioning exercise without WBV (1413±257 W vs. 1353±213 W, p<0.05). a tendency towards superior mean power output during a 15 s all-out sprint (850±119 W vs. 828±101 W, p<0.10). CONCLUSIONS: The overall finding was that preconditioning exercise performed with WBV at 50 Hz seems to have a positive effect on cycling sprint performance in young well trained cyclists. REFERENCES 1. Bullock et al., JSCR, 2008; 22:1371-74 2. Guggenheimer et al., JSCR, 2009; 23:1135-39 3. Rønnestad & Ellefsen, JSCR, 2011;25:3306-10

Dietary nitrate improves sprint performance and cognitive function during prolonged intermittent exercise.

It is possible that dietary nitrate (NO3 (-)) supplementation may improve both physical and cognitive performance via its influence on blood flow and cellular energetics. To investigate the effects of dietary NO3 (-) supplementation on exercise performance and cognitive function during a prolonged intermittent sprint test (IST) protocol, which was designed to reflect typical work patterns during team sports. In a double-blind randomised crossover study, 16 male team-sport players received NO3 (-)-rich (BR; 140 mL day(-1); 12.8 mmol of NO3 (-)), and NO3 (-)-depleted (PL; 140 mL day(-1); 0.08 mmol NO3 (-)) beetroot juice for 7 days. On day 7 of supplementation, subjects completed the IST (two 40-min "halves" of repeated 2-min blocks consisting of a 6-s "all-out" sprint, 100-s active recovery and 20 s of rest), on a cycle ergometer during which cognitive tasks were simultaneously performed. Total work done during the sprints of the IST was greater in BR (123 ± 19 kJ) compared to PL (119 ± 17 kJ; P < 0.05). Reaction time of response to the cognitive tasks in the second half of the IST was improved in BR compared to PL (BR first half: 820 ± 96 vs. second half: 817 ± 86 ms; PL first half: 824 ± 114 vs. second half: 847 ± 118 ms; P < 0.05). There was no difference in response accuracy. These findings suggest that dietary NO3 (-) enhances repeated sprint performance and may attenuate the decline in cognitive function (and specifically reaction time) that may occur during prolonged intermittent exercise.

The Effects Of Swimming And Dry-Land Resistance Training Programme On Non-Swimmers

Abstract Introduction . The aim of the study was to estimate the influence of combined swimming and dry-land resistance training on swimming force, swimming performance and strength in non-swimmers. Material and methods . Thirty male non-swimmers took part in the research. They were randomly assigned to one of the two groups: experimental (n=17) and control (n=13). The experimental group took part in combined swimming and dry-land resistance training. The control group took part in swimming training only. The swimming and dry-land resistance training programme lasted twelve weeks (48 training sessions of swimming and 36 sessions of dry-land resistance training). Average training volume and intensity were the same for all swimmers throughout the study protocol. The training programme included dominant aerobic work in front crawl. Results . Dry-land resistance training applied in the experimental group significantly improved the upper body strength. In spite of the theory that dry-land strength training is probably not specific enough to improve the sprint swim performance, the experimental group tended to demonstrate greater improvement in sprint performance. The imitation of the underwater phase of shoulder work during front crawl provided by the ergometer can be a useful training method in non-swimmers.

Does SAQ training improve the speed and flexibility of young soccer players? A randomized controlled trial

The aim of this study was to determine the effects of a 12week speed, agility and quickness (SAQ) training program on speed and flexibility in young soccer players. One hundred and thirty-two soccer players were randomly assigned to experimental (EG; n=66, mean±SD: age: 18.5±0.4years (range 17–19years); body mass: 71.30±5.93kg; stature: 177.2±6.5cm) and control groups (CG; n=66, mean±SD: age: 18.6±0.6years (range 17–19years); body mass: 70.63±4.87kg; stature: 175.9±5.7cm). The experimental group performed SAQ training whilst the control group undertook straight-line sprint training matched for volume and duration. Sprint performance was assessed using 5 and 10m sprints and a further test including maximal speed, a 20m sprint. Flexibility was assessed using sit and reach, V-sit and reach, leg lift from supine position and lateral leg lift while lying on the side tests. Sprints over 5, 10 and 20m did not differ between groups at baseline, but by week 12, the 5m sprint had significantly improved (P<.05) in the SAQ training group compared to the control group (1.40±0.13 vs. 1.46±0.12s, respectively) although this improvement had a trivial effect size (ES=0.15). The 10m sprint time had improved by 3.3% (P<.01) in the SAQ group with a moderate effect size (ES=0.66). No significant differences (P>.05) for all flexibility tests were found between experimental and control group at baseline and after the training programs. Consequently SAQ training was found to be an effective way of improving sprint time for short distances over 5 and 10m but not over 20m (where maximum speed was achieved) or flexibility. These results indicate that SAQ training may be more effective for improving sprint performance for some soccer players but more research is required to determine ideal training methods for improving acceleration and flexibility in young soccer players.

The effect of resisted sprint training on maximum sprint kinetics and kinematics in youth

Resisted sled towing is a popular and efficient training method to improve sprint performance in adults, however, has not been utilised in youth populations. The purpose therefore was to investigate the effect of resisted sled towing training on the kinematics and kinetics of maximal sprint velocity in youth of different maturation status. Pre- and post-intervention 30 metre sprint performance of 32 children, 18 pre-peak height velocity (PHV) and 14 mid-/post-PHV, were tested on a non-motorised treadmill. The 6-week intervention consisted of ∼12 sessions for pre-PHV and 14 for mid-/post-PHV of resisted sled towing training with each sessions comprised of 8–10 sprints covering 15–30 metres with a load of 2.5, 5, 7.5 or 10% body mass. Pre-PHV participants did not improve sprint performance, while the mid-/post-PHV participants had significant (P < 0.05) reductions (percent change, effect size) in sprint time (−5.76, −0.74), relative leg stiffness (−45.0, −2.16) and relative vertical stiffness (−17.4, −0.76) and a significant increase in average velocity (5.99, 0.76), average step rate (5.65, 0.53), average power (6.36, 0.31), peak horizontal force (9.70, 0.72), average relative vertical forces (3.45, 1.70) and vertical displacement (14.6, 1.46). It seems that sled towing may be a more suitable training method in mid-/post-PHV athletes to improve 30 metre sprint performance.

The effect of green tea extract supplementation on exercise-induced oxidative stress parameters in male sprinters.

BackgroundAlthough research suggests that antioxidant supplementation can protect against exercise-induced muscle damage and oxidative stress, also delayed post-exercise muscle recovery and hindered adaptation to training were reported in the supplemented athletes. PurposeThe purpose of the study was to evaluate the effects of green tea extract (GTE) supplementation on selected blood markers of oxidative stress and muscle damage in sprinters during preparatory phase of their training cycle.MethodsSixteen sprinters participated in a double-blind, randomized, placebo (PL)-controlled crossover study, including two 4-week treatment periods with PL and GTE (980 mg polyphenols daily). The sprinters performed two repeated cycle sprint tests (RST; 4 × 15 s, with 1-min rest intervals), after PL and GTE supplementation. Blood was sampled before (at rest), 5 min after RST, and after the 24-h recovery. The activities of superoxide dismutase (SOD) and glutathione peroxidase were measured in erythrocytes, and total polyphenols, total antioxidant capacity (TAC), uric acid (UA), albumin (AL), malondialdehyde (MDA), and creatine kinase (CK) were determined in blood plasma.ResultsRepeated cycle sprint test performed after PL induced an increase in MDA, TAC, and SOD. Moreover, an increase in UA, AL, and CK was observed after RST irrespective of experimental conditions (PL, GTE). Supplementation with GTE caused an increase in total polyphenols and TAC at rest, and a decrease in MDA and SOD after RST. No significant changes in sprint performance were noted after GTE, as compared to PL.ConclusionsSupplementation with GTE prevents oxidative stress induced by RST in sprinters. Furthermore, GTE supplementation does not seem to hinder training adaptation in antioxidant enzyme system. On the other hand, neither prevention of exercise-induced muscle damage, nor an improvement in sprint performance is noted after GTE administration.

Strength, Speed and Power Characteristics of Elite Rugby League Players

The purpose of this article was to compare strength, speed, and power characteristics between playing position (forwards and backs) in elite rugby league players. A total of 39 first team players (height, 183.8 ± 5.95 cm; body mass, 100.3 ± 10.7 kg; age, 24 ± 3 years) from a National Rugby League club participated in this study. Testing included 10-, 40-m sprint times, sprint mechanics on an instrumented nonmotorized treadmill, and concentric isokinetic hip and knee extension and flexion. Backs, observed to have significantly (p ≤ 0.05) lighter body mass (effect size [ES] = 0.98), were significantly faster (10-m ES = 1.26; 40-m ES = 1.61) and produced significantly greater relative horizontal force and power (ES = 0.87 and 1.04) compared with forwards. However, no significant differences were found between forwards and backs during relative isokinetic knee extension, knee flexion, relative isokinetic hip extension, flexion, prowler sprints, sprint velocity, contact time, or flight time. The findings demonstrate that backs have similar relative strength in comparison with forwards, but run faster overground and produce significantly greater relative horizontal force and power when sprinting on a nonmotorized instrumented treadmill. Developing force and power in the horizontal direction may be beneficial for improving sprint performance in professional rugby league players.

The contribution of vertical explosive strength to sprint performance in children

This study aimed to investigate the relationship between the explosive strength ratio, which is the quotient between maximum height achieved after counter-movement jump with arm and maximum height achieved after standing start jump, and the 30-m sprint performance. Eighty-four children performed a series of 30-m sprints, Counter-movement jump with arm (arm-CMJ) and Starting Long Jump (SLJ) (with both legs) in randomized block order during the same testing session. Pearson’s product moment correlation coefficients (r) were used to determine the relationship between the explosive strength ratio and sprint performance. The coefficients of determination (R 2) were used to examine the amount of explained variance between tests. Stepwise multiple regression analysis was used to estimate the best predictor model of sprint performance. The correlation coefficient between explosive strength Ratio: arm-CMJ/SLJ, 10, and 30-m sprint time was moderate (r = 0.40 and 0.48 respectively). However, correlation with flying time 10 < 30-m sprint time (r = 0.52) was large. The Ratio: arm-CMJ/SLJ was the best single predictor factor (p < 0.001) of the flying time 10 < 30-m sprint time, and explained 27 % of the variance. For improving sprint performance as well as maximal speed and flying time, coaches could ensure the explosive strength ratio as an index to calibrate sprint development program and also for enhancing sport speed in children. They will be able to use this finding to better test and monitor children’s athletes requiring different skills and to evaluate the effects of speed training in children.

Increases in lower-body strength transfer positively to sprint performance: a systematic review with meta-analysis.

Although lower-body strength is correlated with sprint performance, whether increases in lower-body strength transfer positively to sprint performance remain unclear. This meta-analysis determined whether increases in lower-body strength (measured with the free-weight back squat exercise) transfer positively to sprint performance, and identified the effects of various subject characteristics and resistance-training variables on the magnitude of sprint improvement. A computerized search was conducted in ADONIS, ERIC, SPORTDiscus, EBSCOhost, Google Scholar, MEDLINE and PubMed databases, and references of original studies and reviews were searched for further relevant studies. The analysis comprised 510 subjects and 85 effect sizes (ESs), nested with 26 experimental and 11 control groups and 15 studies. There is a transfer between increases in lower-body strength and sprint performance as indicated by a very large significant correlation (r = -0.77; p = 0.0001) between squat strength ES and sprint ES. Additionally, the magnitude of sprint improvement is affected by the level of practice (p = 0.03) and body mass (r = 0.35; p = 0.011) of the subject, the frequency of resistance-training sessions per week (r = 0.50; p = 0.001) and the rest interval between sets of resistance-training exercises (r = -0.47; p ≤ 0.001). Conversely, the magnitude of sprint improvement is not affected by the athlete's age (p = 0.86) and height (p = 0.08), the resistance-training methods used through the training intervention, (p = 0.06), average load intensity [% of 1 repetition maximum (RM)] used during the resistance-training sessions (p = 0.34), training program duration (p = 0.16), number of exercises per session (p = 0.16), number of sets per exercise (p = 0.06) and number of repetitions per set (p = 0.48). Increases in lower-body strength transfer positively to sprint performance. The magnitude of sprint improvement is affected by numerous subject characteristics and resistance-training variables, but the large difference in number of ESs available should be taken into consideration. Overall, the reported improvement in sprint performance (sprint ES = -0.87, mean sprint improvement = 3.11 %) resulting from resistance training is of practical relevance for coaches and athletes in sport activities requiring high levels of speed.

Transference of traditional versus complex strength and power training to sprint performance.

The purpose of this study was to determine the effects of two different strength-power training models on sprint performance. Forty-eight soldiers of the Brazilian brigade of special operations with at least one year of army training experience were divided into a control group (CG: n = 15, age: 20.2 ± 0.7 years, body height: 1.74 ± 0.06 m, and body mass: 66.7 ± 9.8 kg), a traditional training group (TT: n = 18, age: 20.1 ± 0.7 years, body height: 1.71 ± 0.05 m, and body mass: 64.2 ± 4.7 kg), and a complex training group (CT: n = 15, age: 20.3 ± 0.8 years, body height: 1.71 ± 0.07 m; and body mass: 64.0 ± 8.8 kg). Maximum strength (25% and 26%), CMJ height (36% and 39%), mean power (30% and 35%) and mean propulsive power (22% and 28%) in the loaded jump squat exercise, and 20-m sprint speed (16% and 14%) increased significantly (p≤0.05) following the TT and CT, respectively. However, the transfer effect coefficients (TEC) of strength and power performances to 20-m sprint performance following the TT were greater than the CT throughout the 9-week training period. Our data suggest that TT is more effective than CT to improve sprint performance in moderately trained subjects.

Effect of N-acetylcysteine on Cycling Performance after Intensified Training

This investigation examined the ergogenic effect of short-term oral N-acetylcysteine (NAC) supplementation and the associated changes in redox balance and inflammation during intense training. A double-blind randomized placebo-controlled crossover design was used to assess 9 d of oral NAC supplementation (1200 mg·d) in 10 well-trained triathletes. For each supplement trial (NAC and placebo), baseline venous blood and urine samples were taken, and a presupplementation cycle ergometer race simulation was performed. After the loading period, further samples were collected preexercise, postexercise, and 2 and 24 h after the postsupplementation cycle ergometer race simulation. Changes in total antioxidant capacity, ferric reducing ability of plasma, reduced glutathione, oxidized glutathione, thiobarbituric acid-reactive substances, interleukin 6, xanthine oxidase, hypoxanthine, monocyte chemotactic protein 1, nuclear factor κB, and urinary 15-isoprostane F2t concentration were assessed. The experimental procedure was repeated with the remaining supplement after a 3-wk washout. Eight participants completed both supplementation trials. NAC improved sprint performance during the cycle ergometer race simulation (P < 0.001, ηp = 0.03). Supplementation with NAC also augmented postexercise plasma total antioxidant capacity (P = 0.005, ηp = 0.19), reduced exercise-induced oxidative damage (plasma thiobarbituric acid-reactive substances, P = 0.002, ηp = 0.22; urinary 15-isoprostane F2t concentration, P = 0.010, ηp = 0.431), attenuated inflammation (plasma interleukin 6, P = 0.002, ηp = 0.22; monocyte chemotactic protein 1, P = 0.012, ηp = 0.17), and increased postexercise nuclear factor κB activity (P < 0.001, ηp = 0.21). Oral NAC supplementation improved cycling performance via an improved redox balance and promoted adaptive processes in well-trained athletes undergoing strenuous physical training.

Meek males and fighting females: sexually-dimorphic antipredator behavior and locomotor performance is explained by morphology in bark scorpions (Centruroides vittatus).

Sexual dimorphism can result from sexual or ecological selective pressures, but the importance of alternative reproductive roles and trait compensation in generating phenotypic differences between the sexes is poorly understood. We evaluated morphological and behavioral sexual dimorphism in striped bark scorpions (Centruroides vittatus). We propose that reproductive roles have driven sexually dimorphic body mass in this species which produces sex differences in locomotor performance. Poor locomotor performance in the females (due to the burden of being gravid) favors compensatory aggression as part of an alternative defensive strategy, while male morphology is coadapted to support a sprinting-based defensive strategy. We tested the effects of sex and morphology on stinging and sprinting performance and characterized overall differences between the sexes in aggressiveness towards simulated threats. Greater body mass was associated with higher sting rates and slower sprinting within sexes, which explained the greater aggression of females (the heavier sex) and, along with longer legs in males, the improved sprint performance in males. These findings suggest females are aggressive to compensate for locomotor costs of reproduction while males possess longer legs to enhance sprinting for predator evasion and mate finding. Sexual dimorphism in the metasoma (“tail”) was unrelated to stinging and sprinting performance and may best be explained by sexual selection.

Contribution of Vertical Strength and Power to Sprint Performance in Young Male Athletes.

The purpose of this study was to assess the possible contribution of 1RM leg-press strength and jump peak power to 20-m sprint time in young athletes in three maturity groups based on age relative to predicted age of peak height velocity (PHV): Pre (− 2.5 to −1.0 years; n=25), Mid (− 1.0 to 0.5 years; n=26) and Post (0.5 to 2.0 years; n=15). Allometric scaling factors, representing percent difference in 20-m time per percent difference in strength and peak power, were derived by linear regression and were similar in the three maturity groups (−0.16%/% and −0.20%/% for strength and peak power, respectively). The moderate increase in sprint performance Pre to Mid PHV (5.7%) reduced to small (1.9%) and trivial but unclear (0.9%) magnitudes after adjustment for 1RM and peak power, while the moderate increase Mid to Post PHV (4.6%) were still moderate (3.4 and 3.0%) after adjustment. Thus percent differences in strength or power explained most of the maturity-related improvements in sprint performance before PHV age but only some improvements after PHV age. Factors in addition to strength and power should be identified and monitored for development of speed in athletes during puberty.

Contribution of vertical strength and power to sprint performance in young male athletes.

The purpose of this study was to assess the possible contribution of 1RM leg-press strength and jump peak power to 20-m sprint time in young athletes in three maturity groups based on age relative to predicted age of peak height velocity (PHV): Pre (- 2.5 to -1.0 years; n=25), Mid (- 1.0 to 0.5 years; n=26) and Post (0.5 to 2.0 years; n=15). Allometric scaling factors, representing percent difference in 20-m time per percent difference in strength and peak power, were derived by linear regression and were similar in the three maturity groups (-0.16%/% and -0.20%/% for strength and peak power, respectively). The moderate increase in sprint performance Pre to Mid PHV (5.7%) reduced to small (1.9%) and trivial but unclear (0.9%) magnitudes after adjustment for 1RM and peak power, while the moderate increase Mid to Post PHV (4.6%) were still moderate (3.4 and 3.0%) after adjustment. Thus percent differences in strength or power explained most of the maturity-related improvements in sprint performance before PHV age but only some improvements after PHV age. Factors in addition to strength and power should be identified and monitored for development of speed in athletes during puberty.

Effects of Sled Towing on Sprint Starts

Sled towing is a popular method of sprint training. Researchers have struggled to identify a loading scheme that is most appropriate to improve sprint performance in the acceleration phase. The purpose of this study was to determine if loads of 10% body weight (BWT) or 20% BWT produced significantly greater propulsive ground reaction force (GRF) impulse, peak propulsive GRF, or a greater propulsive rate of force development (RFD) than an unweighted sprint start. Seventeen healthy court and field athletes (10 men, 7 women; 20.9 ± 1.1 years) completed 5 starts of each condition (unweighted, 10% BWT, 20% BWT). Participants began each start in an upright staggered stance. Propulsive GRF impulse was greater in the 20% BWT condition than the unweighted condition in both limbs and greater in the 20% BWT condition than the 10% BWT condition in the front leg only, and vertical GRF impulse was greater in the 20% BWT than the unweighted condition. In summary, our results suggest that a 10% BWT load is not sufficient to increase propulsive GRF impulse. A loading scheme of 20% BWT is sufficient to increase propulsive GRF impulse. Coaches seeking to improve sprint starts may observe improvements using a load of 20% BWT during training while towing a sled.

Including arm exercise during a cold water immersion recovery better assists restoration of sprint cycling performance

Sprint (high-intensity) exercise performance is reduced when immediately preceded by cold water immersion (CWI). We aimed to investigate whether this performance effect could be attenuated by combining an active recovery (arm exercise) with hip-level CWI, and whether this attenuation may be related to an effect on core temperature (Tcore ). Participants (n = 8) completed three Wingate tests before (Ex1) and after (Ex2) four different 30-min recovery interventions: CWI at 15 °C (CW15), arm exercise during CWI at 15 °C (CW15+AE), arm exercise during thermoneutral immersion at 34 °C (TW34+AE) and non-immersed arm exercise (AE). After AE and TW34+AE, performance during Ex2 was not different from Ex1; while after CW15+AE and CW15, performance was reduced by 4.9% and 7.6%, respectively. Arm exercise maintained Tcore during recovery in CW15+AE, while it declined to a larger extent upon commencement of Ex2 (-0.9 °C) when compared with CW15 (-0.6 °C). This suggests similar leg muscle cooling during recovery in CW15 and CW15+AE. Without any other significant effects (e.g., on blood lactate), these data suggest that the improvement in sprint performance following an active CWI recovery, over CWI alone, may be related to maintained Tcore and its effect on neurophysiological mechanisms that drive muscle activation, but not by reduced muscle cooling.

Application of a Body-Weight-Supporting Kite for Sprint Running

Improvements in sprint performance at the top level require adaptations concerning force application because ground contact time diminishes with increasing velocity. Applied training methods and devices must provoke appropriate stimuli. A knowledge about positive and negative effects of these stimuli is vital for coaches. The purpose of this study was to determine the angle of attack and lifting and retarding forces of a novel sprint training device that supports the athlete's body weight (BW), thereby decreasing ground contact time during sprints. Three different kite sizes (1.10, 1.75, 2.25 m) were investigated. A bicycle was used to accelerate the National Aeronautics and Space Administration (NASA) parawings (NPW-120, NPW-150, and NPW-170) on an indoor track to acquire data at velocities between 6.5 and 10.5 m · s. During a 5-m interval of constant speed, the resultant force of the kite was recorded on a portable computer by a load cell. The angle of attack was determined by a high-speed camera, and the mean velocity in the 5-m sector was measured by a laser gauge. Lifting and retarding forces were derived from the resultant force and angle of attack. Quadratic regression equations for lifting and retarding forces, depending on the velocity, were calculated for all 3 NPWs. A clear difference (p < 0.001) depending on the kite size was revealed for lifting and retarding forces. These forces also indicated high correlation coefficients related to velocity (r > 0.98; p < 0.001), whereas the angle of attack remained almost constant across the entire velocity range in all NPWs, yielding a lift-to-drag ratio of 2.35. Because of the kite's small retarding forces, we recommend the application of the NPW during the high-speed phase of sprinting with lifting force probably counteracting adverse effects. By adding a towing system, the retarding force can be fine tuned, erased, or turned into overspeed assistance, thereby emphasizing BW support.

The Back Squat and the Power Clean: Elicitation of Different Degrees of Potentiation

To compare the acute effects of back squats and power cleans on sprint performance. Thirteen elite junior rugby league players performed 20-m linear sprints before and 7 min after 2 different conditioning activities or 1 control condition. The conditioning activities included 1 set of 3 back squats or power cleans at 90% 1-repetition maximum. A 2 × 2 repeated-measures ANOVA was used to compare preconditioning and postconditioning changes in sprint performance. Both the back-squat and power-clean conditioning activities demonstrated a potentiation effect as indicated by improved sprint time (back squat: P = .001, ES = -0.66; power cleans: P = .001, ES = -0.92), velocity (back squat: P = .001, ES = 0.63; power cleans: P = .001, ES = 0.84), and average acceleration over 20 m (back squat: P = .001, ES = 0.70; power cleans: P = .001, ES = 1.00). No potentiation effect was observed after the control condition. Overall, the power clean induced a greater improvement in sprint time (P = .042, ES = 0.83), velocity (P = .047, ES = 1.17), and average acceleration (P = .05, ES = 0.87) than the back squat. Back-squat and power-clean conditioning activities both induced improvements in sprint performance when included as part of a potentiation protocol. However, the magnitude of improvement was greater after the power cleans. From a practical perspective, strength and conditioning coaches should consider using power cleans rather than back squats to maximize the performance effects of potentiation complexes targeting the development of sprint performance.