Warm-up Conditions Research Articles

The Effect of Warm-Up With Whole-Body Vibration vs. Cycle Ergometry on Isokinetic Dynamometry

The purpose of this study was to compare the effects of warm-up protocols using either whole-body vibration (WBV) or cycle ergometry (CE) on peak torque at 3 different isokinetic speeds and on fatigue in the knee extension exercise. Twenty-seven recreationally trained (age = 23.59 ± 3.87 years) men (n = 14) and women (n = 13) were tested at 3 different isokinetic speeds (60, 180, 300°·s-1) after either WBV or CE warm-up. The WBV consisted of intermittent bouts of 30 seconds of isometric squats at various degrees of hip and knee flexion for a total of 5 minutes. The CE consisted of 5 minutes of pedaling a cycle ergometer at 65-85% of age-predicted max heart rate. Comparisons between the warm-up conditions were analyzed using repeated measures analysis of variance. For the fatigue comparison, subjects completed 50 continuous concentric knee extensions at 240°·s-1. Means from the first 3 repetitions were compared to means from the final 3 repetitions to establish a fatigue index. Conditions were compared through an independent T-test. No significant (p > 0.05) differences were discovered between warm-up conditions at any speed or on the fatigue index. Means were virtually identical at 60°·s-1 (WBV = 142.14 ± 43.61 ft lb-1; CE = 140.64 ± 42.72 ft lb-1), 180° s-1 (WBV = 93.88 ± 35.18 ft lb-1; CE = 96.36 ± 31.53 ft lb-1), and 300°·s-1 (WBV = 78.36 ± 26.04 ft lb-1; CE = 80.13 ± 26.08), and on fatigue percentage (WBV = 51.14 ± 10.06%; CE = 52.96 ± 9.19%). These data suggest that the more traditional 5-minute cycle ergometer warm-up elicits results comparable to a less common vibration warm-up. The findings of this study are that these modalities are comparable under the tested conditions.

Aerobic activity before and following short-duration static stretching improves range of motion and performance vs. a traditional warm-up

Many activities necessitate a high degree of static joint range of motion (ROM) for an extended duration. The objective of this study was to examine whether ROM could be improved with a short duration and volume of static stretching within a warm-up, without negatively impacting performance. Ten male recreationally active participants completed 2 separate protocols to examine changes in ROM and performance, respectively, with different warm-ups. The warm-up conditions for the ROM protocol were static stretching (SS), consisting of 6 repetitions of 6 s stretches; 10min of running prior to the SS (AS); and 5 min of running before and after the SS (ASA). The performance protocol included a control condition of 10min of running. Measures for the ROM protocol included hip flexion ROM, passive leg extensor tension, and hamstring electromyographic (EMG) activity at pre-warm-up, and at 1, 10, 20, and 30min post-warm-up. Performance measures included countermovement jump (CMJ) height, reaction time (RT), movement time (MT), and balance at pre-warm-up and at 1 and 10min post-warm-up. The ASA produced greater ROM overall than the SS and AS conditions (p< 0.0001), persisting for 30min. There were no significant alterations in passive muscle tension or EMG. For the performance protocol, there were no main effects for condition, but there was a main effect for time, with CMJ height being greater at 1 and 10min post-warm-up (p = 0.0004). Balance ratios and MT improved at 10min post-warm-up (p< 0.0001). Results indicate that the ASA method can provide ROM improvements for 30min with either facilitation or no impairment in performance. This may be especially important for athletes who substitute later into a game with minimal time for a full warm-up.

Effect of Functional Isometric Squats on Vertical Jump in Trained and Untrained Men

Functional isometrics (FIs) combine dynamic and isometric muscle actions and may hyperstimulate the nervous system leading to an enhanced postactivation potentiation (PAP) and improved subsequent performance. The purpose of this study was to investigate the impact of an FI squat on the countermovement vertical jump (CMVJ) in resistance trained and untrained men. Thirteen trained men (age: 22.8 +/- 3.2 years, mass: 90.0 +/- 16.3 kg, and height: 178.9 +/- 7.1 cm) and 8 untrained men (age: 28.5 +/- 5.9 years, mass: 101.5 +/- 23.0 kg, and height: 177.0 +/- 4.8 cm) participated. On separate days, subjects performed CMVJs after 2 different warm-up conditions. The warm-up conditions consisted of either 5 minutes of low-intensity cycling or 5 minutes of low-intensity cycling plus a 3-second FI squat with 150% of their 1 repetition maximum (1RM). A 2 x 3 repeated-measures analysis of variance with Bonferroni post hoc revealed that when comparing the 2 warm-up conditions in the trained subjects, a significant increase (p < 0.05) in CMVJ occurred at 4 minutes (2.4 cm, +5.1%) post-FI squat. This increase was maintained when subjects were retested at 5 minutes post (2.6 cm, + 5.5%). No significant difference in CMVJ was detected in the untrained group (p = 0.49). Results support the addition of an FI squat performed at 150% of 1RM to a low-intensity cycling warm-up to enhance PAP in resistance trained but not in untrained men as measured by CMVJ. Practically, adding functional isometrics to a warm-up scheme may significantly enhance acute, short-term power output in resistance trained men.

Effect of Whole-Body Vibration Warm-Up on Bat Speed in Women Softball Players

Whole-body vibration (WBV) may enhance human performance via augmented muscular strength and motor function if used before performance. Because warm-up is a crucial aspect of preparation for performance, it remains unknown if WBV may enhance bat speed. The purpose of this study was to investigate the effect of WBV warm-up on bat speed. Eleven National Collegiate Athletic Association division I and 11 recreationally trained female softball players volunteered to participate. Subjects randomly performed 3 different warm-up conditions consisting of WBV alone, dry swings alone (DS), and WBV with dry swings (WBVDS). Whole-body vibration was performed on a pivotal vibration platform at a frequency of 25 Hz and an amplitude of 13 mm for one 30-second bout. Thirty seconds after each warm-up condition, 5 maximal bat swings were recorded. There was no significant (p > 0.05) difference between groups by training status, and there was no significant (p > 0.05) difference between WBV (42.39 +/- 9.83 mph), DS (40.45 +/- 11.00 mph), or WBVDS (37.98 +/- 12.40 mph) conditions. These results indicate that WBV warm-up may be used in place of DS to achieve similar bat speeds. Future research should investigate different combinations of WBV warm-up using various frequencies, durations, amplitudes, and rest times.

An Investigation into the Effects of Different Warm-Up Modalities on Specific Motor Skills Related to Soccer Performance

The aim of this study was to investigate the effect of different warm-up stretch modalities on specific high-speed motor capabilities important to soccer performance. Twenty-seven male soccer players performed 3 warm-up conditions, active warm-up (WU), WU with static stretching (SPS), and WU with dynamic stretching (ADS). Heart rate, countermovement jump, 20-m sprint, and Balsom agility tests were performed after each intervention. Vertical jump heights were significantly greater (p < 0.01) in the WU and ADS conditions compared to those in the SPS trial. The 20-m sprint and agility times showed that the SPS condition was significantly slower (p < 0.01) than the WU and ADS conditions, with the ADS trial being significantly faster (p < 0.05) than the WU condition. Heart rate was significantly higher (p < 0.01) for participants post-WU and -ADS trials compared to the SPS condition. These findings suggest that the superior performance of the dynamic stretch and warm-up-only conditions compared to the static stretch condition may be linked to increases in heart rate. The reasons for the dynamic stretch trial superiority compared to the warm-up condition are less clear and as yet to be established. We recommend for optimal performance, specific dynamic stretches be employed as part of a warm-up, rather than the traditional static stretches.

Preexercise Static Stretching Effect on Leaping Performance in Elite Rhythmic Gymnasts

The aim of this study was to examine the acute effects of static stretching (SS) on technical leaps performance in rhythmic gymnastics. Thirty-eight gymnasts (age 14.13 +/- 3.2 years), competing at the international and national levels, performed vertical jumps (squat jump, countermovement jump, hopping test [HT]) and technical leaps (split leap with leg stretched [SL], split leap with ring [RG], split leap with back bend of the trunk [BBT]) assessed in 2 different conditions: after SS and after their usual typical warm-up (TWU) as control conditions. Jumps and leaps flight time (FT) and ground contact time (GCT) parameters were evaluated by OptoJump. Leap performance was simultaneously evaluated by scores awarded by judges. For each dependent variable, the effect of warm-up condition (TWU and SS) was examined by a paired-sample t-test. A multiple regression analysis determined the amount of variance in judges' scores from the FT and GCT variables. Results revealed that vertical jumps FT was not affected by SS warm-up. Ground contact time of HT significantly increased after SS warm-up (p < 0.01). Static stretching reduced significantly (p < 0.01) the technical leap FT (decrements: SL = 7.1%, RG = 7.2%, and BBT = 6.4%). The results showed no significant effects of SS on technical leaps GCT. Static stretching significantly reduced (p < 0.001) the scores awarded by the judges. The FT was the main predictor of scores of the 3 technical leaps accounting for 9-30% of variance in both warm-up conditions. This study suggests that SS before leaping performance may negatively affect rhythmic gymnastics judges' evaluation.

Effect of Warm-Ups Involving Static or Dynamic Stretching on Agility, Sprinting, and Jumping Performance in Trained Individuals

The objective of the present study was to investigate the effects of static and dynamic stretching alone and in combination on subsequent agility, sprinting, and jump performance. Eight different stretching protocols: (a) static stretch (SS) to point of discomfort (POD); (b) SS less than POD (SS<POD); (c) dynamic stretching (DS); (d) SS POD combined with DS (SS POD + DS); (v) SS<POD combined with DS (SS<POD + DS); (vi) DS combined with SS POD (DS + SS POD); (vii) DS combined with SS<POD (DS + SS<POD); and (viii) a control warm-up condition without stretching were implemented with a prior aerobic warm-up and followed by dynamic activities. Dependent variables included a 30-m sprint, agility run, and jump tests. The control condition (4.2 +/- 0.15 seconds) showed significant differences (p = 0.05) for faster times than the DS + SS<POD (4.28s +/- 0.17) condition in the 30-m (1.9%) sprint. There were no other significant differences. The lack of stretch-induced impairments may be attributed to the trained state of the participants or the amount of time used after stretching before the performance. Participants were either professional or national level elite athletes who trained 6-8 times a week with each session lasting approximately 90 minutes. Based on these findings and the literature, trained individuals who wish to implement static stretching should include an adequate warm-up and dynamic sport-specific activities with at least 5 or more minutes of recovery before their sport activity.

A theoretical study for one-dimensional modeling for VOC in a catalytic converter

Modeling for catalytic oxidation of a volatile organic compound, acetaldehyde for the purpose of controlling tail-pipe emissions from vehicular exhaust was carried out. The model developed was one-dimensional unsteady state model, using mass and energy balance equations to predict results for acetaldehyde conversion in an adiabatic monolith operating under warm-up conditions. The equations consisted of a set of partial differential equations that are coupled and solved using Backward Implicit Scheme. Analysis of the behavior of the converter during warm up period was carried out and it was observed that the warm up was faster for a fresh catalyst and this warm up period could be reduced by introducing hot incoming exhaust gas at higher temperature.

The Effects of Precompetition Massage on the Kinematic Parameters of 20-m Sprint Performance

The purpose of this study was to investigate what effect precompetition massage has on short-term sprint performance. Twenty male collegiate games players, with a minimum training/playing background of 3 sessions per week, were assigned to a randomized, counter-balanced, repeated-measures designed experiment used to analyze 20-m sprints performance. Three discrete warm-up modalities, consisting of precompetition massage, a traditional warm-up, and a precompetition massage combined with a traditional warm-up were used. Massage consisted of fast, superficial techniques designed to stimulate the main muscle groups associated with sprint running. Twenty-meter sprint performance and core temperature were assessed post warm-up interventions. Kinematic differences between sprints were assessed through a 2-dimensional computerized motion analysis system (alpha level p <or= 0.05). Results indicated that sprint times in the warm-up and massage combined with warm-up conditions were significantly faster than massage alone. Also, step rate and mean knee velocity were found to be significantly greater in the warm-up and massage combined with warm-up modalities when compared to massage alone. No significant differences were demonstrated in any measures when the warm-up and massage and warm-up combined conditions were compared. Massage as a preperformance preparation strategy seems to decrease 20-m sprint performance when compared to a traditional warm-up, although its combination with a normal active warm-up seems to have no greater benefit then active warm-up alone. Therefore, massage use prior to competition is questionable because it appears to have no effective role in improving sprint performance.

A Method to Determine Fuel Transport Dynamics Model Parameters in Port Fuel Injected Gasoline Engines During Cold Start and Warm-Up Conditions

In order to meet stringent emission standards, it is essential to have a precise control of air-fuel ratio (AFR) under cold start and warm-up conditions. This requires an understanding of the fuel transport dynamics in the intake system during these conditions. This study centers on estimating the parameters of a fuel transport dynamics model during engine operation at different thermal conditions ranging from cold start to fully warmed-up conditions. A method of system identification based on perturbing fuel injection rate is used to find fuel dynamics parameters in a port fuel injected (PFI) spark ignition engine. Since there was no cold chamber available to prepare cold start conditions, a new method was utilized to simulate cold start conditions. The new method can be applied on PFI engines, which use closed valve injection timing. A four-cylinder PFI engine is tested for different thermal conditions from −15°C to 82°C at a range of engine speeds and intake manifold pressures. A good agreement is observed between simulated and experimental AFR for 52 different transient operating conditions presented in this study. Results indicate that both fuel film deposit factor (X) and fuel film evaporation time constant (τf) decrease with increasing coolant temperature or engine speed. In addition, an increase in the intake manifold pressure results in an increase in X while causes a decrease in τf.

An investigation into the possible physiological mechanisms associated with changes in performance related to acute responses to different preactivity stretch modalities

The aim of this study was to explore the potential mechanisms underlying performance changes linked to different warm-up stretch modalities. Twenty-one male collegiate-semiprofessional soccer players (age, 20.8 +/- 2.3 years) performed under 3 different warm-up conditions: a no-stretch warm-up (WU), a warm-up including static passive stretches (SPS), and a warm-up incorporating static dynamic stretches (SDS). Countermovement jump, drop jump, peak torque, heart rate, core temperature, movement kinematics, and electromyography (EMG) were recorded for each intervention. Significant increases (p < 0.001) in performance were recorded for the countermovement, drop jump, and peak torque measures when the SDS was compared with the WU and SPS trials. When mechanism data were analysed, heart rate was significantly higher (p < 0.001) in the SDS condition compared with the SPS and WU conditions (a pattern also shown with core temperature), whereas the WU condition heart rate was also significantly higher than the SPS condition heart rate. When EMG data were examined for the rectus femoris muscle, significantly greater (p < 0.01) muscle activity was observed in the SDS condition compared with the SPS condition. It seems the most likely mechanisms to explain the increase in performance in the SDS condition compared with the SPS condition are increased heart rate, greater muscle activity, and increased peak torque.

Effect Of Weighted Jump Warm-Up On Vertical Jump In Division II Female Volleyball Players

Dynamic warm-up strategies are designed to positively impact performance. Research suggests that warm-ups which elicit a post activation potentiation (PAP) effect via high intensity muscular contractions may increase performance in subsequent activities requiring strength and power. The purpose of this investigation was to determine if a functional, dynamic, volleyball specific warm-up that included weighted jumps would elicit a PAP effect and increase subsequent vertical jump height. Ten trained female Division II volleyball players participated (age = 19.8 + 1.8 yrs; mass = 71.7 + 9.7 kg; ht = 167.8 + 23.9 cm). Subjects were at week 6 of their off-season conditioning program. Besides volleyball specific strength and conditioning, per NCAA guidelines, each player accumulates 2 hrs/wk of individual volleyball practice during this time period. Two different warm-up conditions lasting ∼ 5-7 minutes were individually employed at two different training sessions within one week. The first warm-up condition consisted of a functional, dynamic warm-up of light jogging, high knees, carioca, shuffling, ankle pops (all at 3 sets at 20 yds ea.), pogos (2 × 15 sec.), and tuck jumps (1 × 15 sec.). The second warm-up condition was identical to the first, except for the addition of 1 × 10 maximal vertical jumps with countermovement while wearing a weight vest loaded with 20% of their individual bodyweight. Starting at 4-minutes post warm-up in each condition, maximal vertical jump was assessed in two conditions: 1) 2-hand standing block vertical jump (SBVJ), and 2) 1-hand 3-step approach vertical jump (AVJ). Three trials per each condition were given, with 15 sec. rest intervals allowed between trials. The highest point touched on a vertical jump tester was recorded for each trial. The average of the three trials was used for data analysis. Paired Samples T-test was used to determine if there was a significant difference (p < 0.05) in vertical jump height (i.e., height touched) between the two conditions. The results of this study were mixed. No significant difference (p > 0.05) occurred in vertical jump height in the SBVJ condition between the two different warm-ups (262.1 vs. 263.0 cm, warm-up vs. warm-up with weight vest, respectively). However, the AVJ was significantly higher by 2.7 cm (p < 0.05; 275.1 vs. 277.8 cm) after the subjects added the weight vest to their warm-up routine. This study demonstrates that a functional, dynamic warm-up with the addition of weight jumps for 1 × 10 at 20% of bodyweight increases 3-step approach vertical jump ability in female collegiate volleyball players. However, no effect was seen in 2-hand standing block vertical jump ability. This may possibly be explained by the difference in the forces and energy involved during the stretch-shortening cycle in a 3-step approach vertical jump vs. a stationary standing block vertical jump. The coach may consider using a functional, dynamic, athletic warm-up that includes jumps with resistance to optimize performance in sports like volleyball where vertical jumps with an approach are key components of competition.

Effect of Static and Dynamic Stretching on Vertical Jump Performance in Collegiate Women Volleyball Players

The purpose of this study was to determine the effect of stretching on peak jump height during a series of vertical jumps, specifically focusing on a) static stretching (SS), b) dynamic stretching (DS) and c) no stretching (NS) performed immediately before a series of countermovement vertical jumps (CMJ). Twelve female collegiate volleyball players (mean +/- SD; age 19.5 +/- 1.1 yr; height 1.71 +/- 0.06 m; mass 71.3 +/- 8.54 kg) volunteered for this study. Data collection lasted a total of 3 weeks, and each subject performed all 3 stretching protocols, 1 session per week, with 1 week between sessions. The order of the stretching protocols was randomized for each subject. During each testing session, all subjects performed a 5-minute light jog as a warm-up, followed by 8 minutes of 1 of the stretching protocols. One minute after the completion of each protocol, 5 maximal CMJ were performed on a force platform, with each jump separated by 1 minute of passive recovery. Jump heights were calculated by integrating the vertical force trace. There were no significant differences between the SS, DS, and NS conditions for any of the jumps (p > 0.05). Despite the lack of significant effects for the group, there were notable individual responses to each of the warm-up conditions. Practitioners should be aware of the individual responses of their athletes to different types of warm-up protocols before athletic performance and the possible impact of prescribing or eliminating certain exercises.

Acute Effects of Dynamic Stretching, Static Stretching, and Light Aerobic Activity on Muscular Performance in Women

The purpose of this study was to compare three warm-up protocols--static stretching, dynamic stretching, and light aerobic activity--on selected measures of range of motion and power in untrained females and to investigate the sustained effects at 5 and 30 minutes after warm-up. A total of 24 healthy females (ages 23-29 years) attended one familiarization session and three test sessions on nonconsecutive days within 2 weeks. A within-subject design protocol with the testing investigators blinded to the subjects' warm-up was followed. Each session started with 5 minutes of light aerobic cycling followed by pretest baseline measures. Another 5 minutes of light aerobic cycling was completed and followed by one of the three randomly selected warm-up interventions (static stretching, dynamic stretching, or light aerobic activity). The following posttest outcome measures were collected 5 and 30 minutes following the intervention: modified Thomas test, countermovement jump, and isometric time to peak force knee extension measured by dynamometer. Analysis of the data revealed significant time effects on range of motion and countermovement jump changes. No significant differences (p > 0.05) were found between the warm-up conditions on any of the variables. The variation in responses to warm-up conditions emphasizes the unique nature of individual reactions to different warm-ups; however, there was a tendency for warm-ups with an active component to have beneficial effects. The data suggests dynamic stretching has greater applicability to enhance performance on power outcomes compared to static stretching.

Effect of Warm-up With Different Weighted Bats on Normal Baseball Bat Velocity

Traditionally, baseball players have used a heavy bat for warm-up before competition. Because bat velocity is an essential component to hitting a baseball, and because players warm up differently, there is a need to investigate the best way to maximize post warm-up bat velocity. The purpose of this study was to determine the effects of warm-up with different weighted bats on normal baseball bat velocity. Nineteen recreational male baseball players (age, 24.5 +/- 3.9 years; height, 181.1 +/- 8.4 cm; body mass, 87.9 +/- 18.4 kg) participated in this study. Three different randomized warm-up conditions were completed and analyzed for velocity and for their effect on post warm-up normal baseball bat velocity. Subjects were instructed to perform 5 maximal swings with each of 3 different weighted bats-light (LB = 9.6 oz), normal (NB = 31.5 oz), and heavy (HB = 55.2 oz)-followed by 30-second rest and then 5 swings of the NB. Analysis of variance revealed that warm-up velocity of the LB (63.57 +/- 3.58 mph) was significantly (p < 0.05) faster than that of NB (51.25 +/- 3.01 mph) and HB (41.79 +/- 3.01 mph), whereas warm-up velocity of NB was also significantly faster than that of HB. For post warm-up, LB (52.29 +/- 2.68 mph) and NB (50.60 +/- 3.04 mph) produced significantly faster velocity of the normal bat than the HB (48.26 +/- 2.98 mph). Warming up with 5 swings of a light or normal bat appears to increase post warm-up velocity of the normal bat when compared with warming up with a heavy bat after a rest period of 30 seconds. Within the bat weight spectrum of this study, it is suggested that when preparing to hit, 5 warm-up swings with either a light or normal bat will allow a player to achieve the greatest velocity of their normal bat.

Effects Of Warm-up On Peak Torque, Rate Of Torque Development, And Electromyographic And Mechanomyographic Signals

PURPOSE: The purpose of this study was to determine if an active warm-up affects peak torque (PT), rate of torque development (RTD), and the electromyographic (EMG) and mechanomyographic (MMG) signals. METHODS: Twenty-one men (mean age ± SD = 23.9 ± 2.6 y) visited the exercise physiology lab on two occasions. During the first visit they either performed an active warm-up (10 minutes of stationary cycling at 70% of predicted max heart rate) or sat quietly (no warm-up). Participants were then tested for isometric and isokinetic PT (60, 180, and 300 deg/s), and RTD (measured as S-gradient) on an isokinetic dynamometer. EMG and MMG sensors were placed over the vastus lateralis muscle of the right limb to monitor the electrical and mechanical aspects of muscle contractions, respectively. The testing protocol used for the first visit was repeated for the second visit, but the pre-exercise treatment (warm-up, no warm-up) not given during the first visit was administered. RESULTS: The results indicated that an active warm-up did not affect PT, RTD, EMG amplitude, EMG frequency, or MMG frequency (p > 0.05). However, MMG amplitude at 180 deg/s was significantly greater (p < 0.05) in the warm-up condition compared to the no warm-up condition. CONCLUSIONS: The results indicated that warm-up did not affect PT, RTD, EMG amplitude, EMG frequency, or MMG frequency. The increase in MMG amplitude, however, suggests that warm-up may have affected the mechanical properties of muscle by reducing muscular stiffness and/or decreasing intramuscular fluid pressure.

Negative effect of static stretching restored when combined with a sport specific warm-up component

There is substantial evidence that static stretching may inhibit performance in strength and power activities. However, most of this research has involved stretching routines dissimilar to those practiced by athletes. The purpose of this study was to evaluate whether the decline in performance normally associated with static stretching pervades when the static stretching is conducted prior to a sport specific warm-up. Thirteen netball players completed two experimental warm-up conditions. Day 1 warm-up involved a submaximal run followed by 15 min of static stretching and a netball specific skill warm-up. Day 2 followed the same design; however, the static stretching was replaced with a 15 min dynamic warm-up routine to allow for a direct comparison between the static stretching and dynamic warm-up effects. Participants performed a countermovement vertical jump and 20 m sprint after the first warm-up intervention (static or dynamic) and also after the netball specific skill warm-up. The static stretching condition resulted in significantly worse performance than the dynamic warm-up in vertical jump height (−4.2%, 0.40 ES) and 20 m sprint time (1.4%, 0.34 ES) ( p < 0.05). However, no significant differences in either performance variable were evident when the skill-based warm-up was preceded by static stretching or a dynamic warm-up routine. This suggests that the practice of a subsequent high-intensity skill based warm-up restored the differences between the two warm-up interventions. Hence, if static stretching is to be included in the warm-up period, it is recommended that a period of high-intensity sport-specific skills based activity is included prior to the on-court/field performance.

Influence of Closed Skill and Open Skill Warm-ups on the Performance of Speed, Change of Direction Speed, Vertical Jump, and Reactive Agility in Team Sport Athletes

In this study, we evaluated the efficacy of two different dynamic warm-up conditions, one that was inclusive of open skills (i.e., reactive movements) and one that included only preplanned dynamic activities (i.e., closed skills) on the performance of speed, change of direction speed, vertical jump, and reactive agility in team sport athletes. Fourteen (six male, eight female) junior (mean +/- SD age, 16.3 +/- 0.7 year) basketball players participated in this study. Testing was conducted on 2 separate days using a within-subjects cross-over study design. Each athlete performed a standardized 7-minute warm-up consisting of general dynamic movements and stretching. After the general warm-up, athletes were randomly allocated into one of two groups that performed a dynamic 15-minute warm-up consisting entirely of open or closed skills. Each of the warm-up conditions consisted of five activities of 3 minute duration. At the completion of the warm-up protocol, players completed assessments of reactive agility, speed (5-, 10-, and 20-m sprints), change of direction speed (T-test), and vertical jump. No significant differences (p > 0.05) were detected among warm-up conditions for speed, vertical jump, change of direction speed, and reactive agility performances. The results of this study demonstrate that either open skill or closed skill warm-ups can be used effectively for team sport athletes without compromising performance on open skill and closed skill tasks.

Promising zeolite-type hydrocarbon trap catalyst by a knowledge-based combinatorial approach

Libraries consisting of more than 100 zeolite samples were prepared and examined for developing a promising HC trap catalyst. Parallel adsorptions of toluene onto the catalyst samples were conducted over a 10 × 10 array reactor under dry and wet conditions with or without a heating process three knowledge-based conditions for developing an automotive catalyst during the cold-start period. FAU and BEA type zeolites revealed a high performance of toluene adsorption under the dry condition. However, FAU type zeolite significantly decreased the amount of toluene adsorbed in the presence of water in the feed gas stream, mainly due to the hydrophobicity of the catalyst surface. Over Beta type zeolites, the toluene adsorbed was found to be considerably preserved, even after forced desorption temperature-ramping to the warm-up condition of an automotive engine. Li, K, or Ag ion-exchanged Beta zeolites seem to be particularly promising as an HC trap catalyst.

The Effect of Warm-Up on High-Intensity, Intermittent Running Using Nonmotorized Treadmill Ergometry

The aim of this study was to investigate the effect of previous warming on high-intensity intermittent running using nonmotorized treadmill ergometry. Ten male soccer players completed a repeated sprint test (10 x 6-second sprints with 34-second recovery) on a nonmotorized treadmill preceded by an active warm-up (10 minutes of running: 70% VO2max; mean core temperature (Tc) 37.8 +/- 0.2 degrees C), a passive warm-up (hot water submersion: 40.1 +/- 0.2 degrees C until Tc reached that of the active warm-up; 10 minutes +/- 23 seconds), or no warm-up (control). All warm-up conditions were followed by a 10-minute static recovery period with no stretching permitted. After the 10-minute rest period, Tc was higher before exercise in the passive trial (38.0 +/- 0.2 degrees C) compared to the active (37.7 +/- 0.4 degrees C) and control trials (37.2 +/- 0.2 degrees C; p < 0.05). There were no differences in pre-exercise oxygen consumption and blood lactate concentration; however, heart rate was greater in the active trial (p < 0.05). The peak mean 1-second maximum speed (MxSP) and group mean MxSP were not different in the active and passive trials (7.28 +/- 0.12 and 7.16 +/- 0.10 m x s(-1), respectively, and 7.07 +/- 0.33 and 7.02 +/- 0.24 m x s(-1), respectively; p > 0.05), although both were greater than the control. The percentage of decrement in performance fatigue was similar between all conditions (active, 3.4 +/- 1.3%; passive, 4.0 +/- 2.0%; and control, 3.7 +/- 2.4%). We conclude that there is no difference in high-intensity intermittent running performance when preceded by an active or passive warm-up when matched for post-warm-up Tc. However, repeated sprinting ability is significantly improved after both active and passive warm-ups compared to no warm-up.