Warm-up Procedure Research Articles

Effects of warm-up and precooling on endurance performance in the heat

Objective: To examine the effects of different thermoregulatory preparation procedures (warm-up (WU), precooling (PC), control (C)) on endurance performance in the heat. Methods: 20 male subjects completed three treadmill runs...

BALLISTIC STRETCHING INCREASES FLEXIBILITY AND ACUTE VERTICAL JUMP HEIGHT WHEN COMBINED WITH BASKETBALL ACTIVITY

Stretching is often included as part of a warm-up procedure for basketball activity. However, the efficacy of stretching with respect to sport performance has come into question. We determined the effects of 4 different warm-up protocols followed by 20 minutes of basketball activity on flexibility and vertical jump height. Subjects participated in 6 weeks (2 times per week) of warm-up and basketball activity. The warm-up groups participated in ballistic stretching, static stretching, sprinting, or basketball shooting (control group). We asked 3 questions. First, what effect does 6 weeks of warm-up exercise and basketball play have on both flexibility and vertical jump height? We measured sit and reach and vertical jump height before (week −1) and after (week 7) the 6 weeks. Flexibility increased for the ballistic, static, and sprint groups compared to the control group (p < 0.0001), while vertical jump height did not change for any of the groups. Our second question was what is the acute effect of each warm-up on vertical jump height? We measured vertical jump immediately after the warm-up on 4 separate occasions during the 6 weeks (at weeks 0, 2, 4, and 6). Vertical jump height was not different for any group. Finally, our third question was what is the acute effect of each warm-up on vertical jump height following 20 minutes of basketball play? We measured vertical jump height immediately following 20 minutes of basketball play at weeks 0, 2, 4, and 6. Only the ballistic stretching group demonstrated an acute increase in vertical jump 20 minutes after basketball play (p < 0.05). Coaches should consider using ballistic stretching as a warm-up for basketball play, as it is beneficial to vertical jump performance.

Ballistic Stretching Increases Flexibility and Acute Vertical Jump Height When Combined With Basketball Activity

Stretching is often included as part of a warm-up procedure for basketball activity. However, the efficacy of stretching with respect to sport performance has come into question. We determined the effects of 4 different warm-up protocols followed by 20 minutes of basketball activity on flexibility and vertical jump height. Subjects participated in 6 weeks (2 times per week) of warm-up and basketball activity. The warm-up groups participated in ballistic stretching, static stretching, sprinting, or basketball shooting (control group). We asked 3 questions. First, what effect does 6 weeks of warm-up exercise and basketball play have on both flexibility and vertical jump height? We measured sit and reach and vertical jump height before (week -1) and after (week 7) the 6 weeks. Flexibility increased for the ballistic, static, and sprint groups compared to the control group (p < 0.0001), while vertical jump height did not change for any of the groups. Our second question was what is the acute effect of each warm-up on vertical jump height? We measured vertical jump immediately after the warm-up on 4 separate occasions during the 6 weeks (at weeks 0, 2, 4, and 6). Vertical jump height was not different for any group. Finally, our third question was what is the acute effect of each warm-up on vertical jump height following 20 minutes of basketball play? We measured vertical jump height immediately following 20 minutes of basketball play at weeks 0, 2, 4, and 6. Only the ballistic stretching group demonstrated an acute increase in vertical jump 20 minutes after basketball play (p < 0.05). Coaches should consider using ballistic stretching as a warm-up for basketball play, as it is beneficial to vertical jump performance.

Acute Effects of Whole-Body Vibration on Muscle Activity, Strength, and Power

The purpose of this study was to investigate the effects of a single bout of whole-body vibration on isometric squat (IS) and countermovement jump (CMJ) performance. Nine moderately resistance-trained men were tested for peak force (PF) during the IS and jump height (JH) and peak power (PP) during the CMJ. Average integrated electromyography (IEMG) was measured from the vastus medialis, vastus lateralis, and biceps femoris muscles. Subjects performed the 2 treatment conditions, vibration or sham, in a randomized order. Subjects were tested for baseline performance variables in both the IS and CMJ, and were exposed to either a 30-second bout of whole-body vibration or sham intervention. Subjects were tested immediately following the vibration or sham treatment, as well as 5, 15, and 30 minutes posttreatment. Whole-body vibration resulted in a significantly higher (p < or = 0.05) JH during the CMJ immediately following vibration, as compared with the sham condition. No significant differences were observed in CMJ PP; PF during IS or IEMG of the vastus medialis, vastus lateralis, or biceps femoris during the CMJ; or IS between vibration and sham treatments. Whole-body vibration may be a potential warm-up procedure for increasing vertical JH. Future research is warranted addressing the influence of various protocols of whole-body vibration (i.e., duration, amplitude, frequency) on athletic performance.

Ballistic Stretching Increases Flexibility and Acute Vertical Jump Height When Combined with Basketball Activity

2360 Stretching is often included as part of a warm-up procedure for basketball activity. However, the efficacy of stretching with respect to performance has come into question. PURPOSE: We determined the effects of four different warm-up protocols and subsequent basketball activity on flexibility and vertical jump height. METHODS: Forty-three beginning and intermediate basketball students participated in six weeks (2x/week) of basketball activity. Subjects were divided into four groups according to type of warm-up activity: ballistic stretching, static stretching, sprinting, or basketball shooting (control group). Subjects engaged in a 10 minute overall warm-up as follows: 3 minutes of basketball running drills followed by 7 minutes of their experimental warm-up. The warm-up was followed by 20 minutes of basketball play. We measured flexibility via sit and reach and vertical jump height before (at week −1) and after (at week 7) the six weeks (PRE SIT, POST SIT, PRE VJ, and POST VJ, respectively). In addition, we measured vertical jump height every two weeks immediately after the warm-up (wk 0 pre, wk 2 pre, wk 4 pre, wk 6 pre) and immediately after the 20 minute basketball play (wk 0 post, wk 2 post, wk 4 post, wk 6 post). RESULTS: Flexibility increased for the ballistic, static, and sprint groups compared to the control group(p<0.0001). The ballistic group had the greatest increase (3.3 ± 3.3 cm), followed by the sprint (3.0 ± 2.7 cm), and static (2.2 ± 3.0 cm). Vertical jump height was not different over the six weeks for any of the groups (pre VJ; wks 0,2,4,6 pre; and post VJ). However, the ballistic group demonstrated an increase in vertical jump after basketball play when compared to the previous measure on the same day (3.4 ± 2.9 cm increase; p = 0.003). CONCLUSIONS: Ballistic stretching had the greatest increase in flexibility, as well an increase in vertical jump height that was not observed in other groups when followed by 20 min of basketball play. Ballistic stretching can be included as a beneficial component of a basketball warm-up for flexibility and acute vertical jump height increase in recreational basketball participants.

The Effect of Four Different Warm-Ups on the Maximum Vertical Jump Test Scores for Female College Athletes

The effectiveness of two specific and two non-specific warm-ups on the vertical jump test for female athletes was the focus of this research. The four warm-up procedures were: (a) weighted jumping (WT), (b) submaximal vertical jumping (SUB), (c) stretching (ST), and (d) no warm-up (NW). To control for learning and fatigue, a counter-balanced design was used to test all participants over four different days. Thus all groups were tested in a predetermined order. Participants were 15 university female athletes (age 18 to 23 years). After warming up using one of the four warm-up procedures, three vertical jumps were measured and the best score was used for analysis. A single factors repeated measure analysis of variance and LSD post hoc tests revealed that the weighted jump warm-up procedure was statistically superior (p&lt;0.01) to all other warm-up procedures. No warm-up was statistically inferior to all other warm-ups and submaximal vertical jumping was not statistically different than stretching. It was concluded; (a) performing a warmup is better than no warm-up, and (b) utilizing a weighted resistance-jumping warm-up will produce the highest scores when performing the vertical jump test for female athletes.

The Conconi test: methodology after 12 years of application.

The protocol for the determination of the speed/heart rate relationship during incremental exercise previously described (so-called Conconi test) has been refined and in part modified during 12 years of application. The new protocol calls for time-based increments in exercise intensity that are uniform up to submaximal speeds and progressively greater in the final phase. As in the original article (18), the speed/heart rate relationship is linear at low to moderate speed and curvilinear from submaximal to maximal speeds. A method is presented for the mathematical definition of this relationship, with the calculation of the straight-line equation of the linear phase and the identification of the point of transition from the linear to the curvilinear phase (deflection point or heart rate break-point). Analysis of 300 tests selected at random from those in our data base (more than 5,000 tests) has enabled us to show that the speed at which the deflection point occurs is significantly lower (p < 0.001) than that at which the acceleration of the final phase begins. This fact demonstrates that the break-point is not brought on by the final acceleration called for in the test protocol. Analysis of the speed/heart rate relationship allows for the determination of the following additional functional indices: 1) maximal heart rate (in 21 athletes the maximal heart rate attained in the test and that attained while racing were equal); 2) range of heart beats defining the linear part of the speed/heart rate relationship; 3) range of heart beats from the deflection point to maximal heart rate; and 4) maximal aerobic exercise intensity, obtained through extrapolation of the straight-line equation to maximal heart rate. Data are provided on the conditions of the test subject that modify his speed/heart rate relationship, such as incomplete recovery from previous efforts, inadequate warm-up, or inadequate test procedure with too rapid increments in exercise intensity. Finally, criteria for test acceptability are presented.

The warm-up procedure: to stretch or not to stretch. A brief review.

Stretching exercises are either performed alone or with other exercises as part of the athlete's warm-up. The warm-up is designed to increased muscle/tendon suppleness, stimulate blood flow to the periphery, increase body temperature, and enhance free, coordinated movement. The purpose of this paper is to review the literature regarding stretching, with the aim of defining its role during the warm-up. Implications of stretching on muscle/tendon flexibility, minimizing injury, enhancing athletic performance, and generally preparing the athlete for exercise are discussed. Physiology applied to stretching is also discussed together with different related techniques and practical aspects. A proposed model stretching regime is presented based on the literature reviewed.

Molecular Mechanics and Dynamics of an Abasic Frameshift in DNA and Comparison to NMR Data

In a previous publication (Ph. Cuniasse, L.C. Sowers, R. Eritja, B. Kaplan, M.F. Goodman, J.A.H. Cognet, M. Le Bret, W. Guschlbauer and G.V. Fazakerley, Biochemistry 28, 2018 (1989), we determined by two dimensional NMR studies and molecular mechanics calculations the three-dimensional structure of a non-selfcomplementary oligonucleotide: [sequence; see text] where dr, at the center of the first strand, is a model abasic site. In order to explain all the results arising from NMR measurements, we found that an equilibrium between two conformations was necessary. These conformations differ mainly by the sugar pucker of G5 which is C2' endo or C3' endo. The latter is stabilized by addition of counterions between phosphate residues P3 and P4. In this paper, we have constructed systematically, all possible structures as a function of torsion angles delta of dr4 and of G5 by molecular mechanics in the presence or absence of counterions. Since these conformations were not forced with NMR distance measurements, this method allows detailed comparisons between all possible conformations and NMR data. Maps of contour lines of the potential energy, of fits to NMR distance measurements, and of helical twist as a function of torsion angles delta of dr4 and of G5 unravel the difficulties associated with the study of the G5 sugar pucker conformation equilibrium. Sugar puckers and proton distances are very sensitive criteria to monitor molecular dynamics. Relying on these experimental criteria, we have tested many molecular dynamics preparation phases and we propose a new warm-up and equilibration procedure for molecular dynamics. Thus we show with a 290 ps molecular dynamic run that G5 is in conformational equilibrium and that all NMR data are well reproduced.

ADAPTIVE POLE-PLACEMENT CONTROL OF A CONTINUOUS POLYMERIZATION REACTOR

A simulation of the polymerization of methylmethacrylate in a CSTR is adaptively controlled by two types of pole-placement algorithms. The strongly nonlinear polymerization process, exhibiting multiple steady states, presents difficult control problems for conventional feedback controllers. The performance of an adaptive explicit SISO controller and that of an adaptive implicit multivariable controller are compared and evaluated as applied to this process. The plant is identified by a recursive least squares estimator. Modifications made to the estimation algorithm help to maintain adequate closed-loop results. A simple warm-up procedure is introduced that successfully initializes the controller and estimator during plant start-up. Good servo and regulatory control are achieved by both pole-placement schemes.

Superconductivity in H-charged Cu-implanted Pd

A superconducting transition temperature, T c, of 12.4 K has been observed in Pd implanted with Cu ions and electrolytically charged with H at dry ice temperature. A step-wise warmup procedure between 77 and 273 K produces considerable variations in T c. Annealing the Cu-implanted Pd before electrolysis does not change T c to a substantial degree.

Effects of active, passive or no warm-up on the physiological response to heavy exercise.

Six endurance-trained young men were subjected to a 4 min maximal aerobic treadmill run (100% of VO2 max), after active or passive warm-up or rest on separate days. The increase in body temperature during the active and passive warm-up was controlled, so that the temperature reached the same level, before the subject was exposed to the maximal exercise. On average the rectal temperature rose to 38.3 degrees C (range 38.1-38.6 degrees C). The standard work resulted in a significant higher oxygen uptake, lower lactate concentration and higher blood pH when the work was preceded by active warm-up as compared with passive or no warm-up. The difference in total oxygen uptake during the run between the active and passive warm-up procedure was 0.8 1. No significant difference in minute volume of expired air or respiratory quotient was found. It is concluded that the physiological effects of a thorough active warm-up may be of substantial benefit to athletic performance.

Conditions of the first warm-up as a factor in the durability of dinas concrete blocks in the cells of soaking pits

A warm-up procedure was developed for linings of dinas blocks with account taken of the modification conversions which occur in the dinas filler and in the quartzite, and of the thermal stresses set up in the blocks in unilateral heating.

Hydrothermal Growth of Large Sound Crystals of Zinc Oxide

Large (10 to 20 g) macroscopically sound ZnO crystals suitable for preliminary transducer and other studies have been grown hydrothermally at rates of from 10 to 15 mils per day. The factors found to be important in achieving good growth were (1) base concentration of growth solution, (2) temperature difference between dissolving and growth regions, (3) presaturation of growth solution, (4) warm‐up procedure, (5) addition of Li+ to the growth solution to suppress dendrite formation, (6) etching to remove seed damage, and (7) nutrient size. Each of the foregoing factors was studied and is discussed.

The “Looseness” Factor in Speed and O2Consumption of an Anaerobic 100-Yard Dash

Abstract This study tested the hypothesis that the “looseness” factor in sprint running would be enhanced through lessening the resistance of antagonistic muscles and/or their connective tissues by stretching. On the basis of this hypothesis, it was predicted that running times would be improved and metabolic cost reduced as the result of improving joint mobility through stretching. Static stretching was used as a warm-up procedure to allow evaluation of a relatively pure flexibility factor as a contributor to muscular efficiency or “looseness.” Four subjects each ran ten 100-yd. time trials anaerobically. Five trials followed no warm-up and five followed a period of static stretching. Respiratory gas samples were analyzed for gross and net O2, CO2, ventilation rate, and true O2. Differences in running time and all respiratory measures were small in magnitude and none achieved significance at the .05 level.

A new ionization chamber system for regularly checking x-ray therapy machines.

Regular and Frequent checking of x-ray machines is needed to assure accurate dosage values in therapy. Theoretically, the best solution is to measure the output intensity with a Victoreen or similar dosimeter at least once weekly. Unfortunately, the nature of such instruments and measurements normally prevents delegating this task to a technician, and frequent regular checking appears to be limited to larger hospitals and teaching institutions. A more rugged and inexpensive but still accurate instrument, designed specifically for this purpose, is desirable. Both film and ionization chamber monitoring methods have been discussed in the literature. Film monitoring of x-ray output appears to be of limited promise, because of the considerable technical problems involved and the inherent ambiguity in interpretation of density readings (1). Ionization chamber monitors offer the advantage over Victoreen or similar units that the measuring device is permanently mounted in a reproducible location, eliminating positioning errors (2). While readings of such units are of course responsive to tube housing temperature changes (3), this does not present a serious problem if the test is carried out after a prescribed daily warm-up procedure. Early monitor chamber units, such as the well known Weatherwax design, were of copper, with substantial air volumes. As a result, they produced large enough ionization currents to yield a direct reading on a sensitive panel galvanometer. Unfortunately, most modern x-ray machines can accommodate only small monitor chambers; the reduced current necessitates the use of electronic amplification, with some corresponding operation and maintenance problems. In addition, the indications of commercial monitor chambers are frequently not accurately proportional to roentgen intensity. The system to be described here attempts to overcome some of these problems by special chamber design and the use of a condenser discharge method to measure ionization current instead of an amplifier (Figs. 1 to 3). It consists of three units: an ionization chamber mounted beneath the filter, a portable polystyrene capacitor-electroscope assembly, and a charger unit for the capacitor. In use, the capacitor unit is first charged so that the electroscope (a 0–200 mr self-reading pocket dosimeter) reads 0 mr. It is then plugged across the chamber in the tube housing. The machine is operated at useful factors for a time specified by the physicist at calibration. The resulting “milliroent-gen” reading is a direct measure of the current x-ray output rate. For example, if the reading at calibration was 180 mr, and it is reduced 18 mr to 162 mr, a 90 per cent intensity reading is noted in the daily record and reported to the therapist. Design and Operation Considerations Figure 4 shows the construction of the most recent monitor ionization chamber.