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1.  Effects of Dynamic and Static Stretching Within General and Activity Specific Warm-Up Protocols 
The purpose of the study was to determine the effects of static and dynamic stretching protocols within general and activity specific warm-ups. Nine male and ten female subjects were tested under four warm-up conditions including a 1) general aerobic warm-up with static stretching, 2) general aerobic warm-up with dynamic stretching, 3) general and specific warm-up with static stretching and 4) general and specific warm-up with dynamic stretching. Following all conditions, subjects were tested for movement time (kicking movement of leg over 0.5 m distance), countermovement jump height, sit and reach flexibility and 6 repetitions of 20 metre sprints. Results indicated that when a sport specific warm-up was included, there was an 0.94% improvement (p = 0.0013) in 20 meter sprint time with both the dynamic and static stretch groups. No such difference in sprint performance between dynamic and static stretch groups existed in the absence of the sport specific warm-up. The static stretch condition increased sit and reach range of motion (ROM) by 2.8% more (p = 0.0083) than the dynamic condition. These results would support the use of static stretching within an activity specific warm-up to ensure maximal ROM along with an enhancement in sprint performance.
Key pointsActivity specific warm-up may improve sprint performance.Static stretching was more effective than dynamic stretching for increasing static range of motion.There was no effect of the warm-up protocols on countermovement jump height or movement time.
PMCID: PMC3737866  PMID: 24149201
Flexibility; sports performance; jumps; reaction time
2.  Dynamic Warm-Up Protocols, With and Without a Weighted Vest, and Fitness Performance in High School Female Athletes 
Journal of Athletic Training  2006;41(4):357-363.
Context: Recent authors have not found substantial evidence to support the use of static stretching for improving performance, so interest in dynamic warm-up procedures has risen. Our findings may improve the understanding of the acute effects of different types of pre-exercise protocols on performance and may help clinicians develop effective warm-up protocols for sports practice and competition.
Objective: To examine the acute effects of 4 warm-up protocols with and without a weighted vest on anaerobic performance in female high school athletes.
Design: Randomized, counterbalanced, repeated-measures design.
Setting: High school fitness center.
Patients or Other Participants: Eighteen healthy high school female athletes (age = 15.3 ± 1.2 years, height = 166.3 ± 9.1 cm, mass = 61.6 ± 10.4 kg).
Intervention(s): After 5 minutes of jogging, subjects performed 4 randomly ordered warm-up protocols: (1) Five static stretches (2 × 30 seconds) (SS), (2) nine moderate-intensity to high-intensity dynamic exercises (DY), (3) the same 9 dynamic exercises performed with a vest weighted with 2% of body mass (DY2), and (4) the same 9 dynamic exercises performed with a vest weighted with 6% of body mass (DY6).
Main Outcome Measure(s): Vertical jump, long jump, seated medicine ball toss, and 10-yard sprint.
Results: Vertical jump performance was significantly greater after DY (41.3 ± 5.4 cm) and DY2 (42.1 ± 5.2 cm) compared with SS (37.1 ± 5.1 cm), and long jump performance was significantly greater after DY2 (180.5 ± 20.3 cm) compared with SS (160.4 ± 20.8 cm) ( P ≤ .05). No significant differences between trials were observed for the seated medicine ball toss or 10-yard sprint.
Conclusions: A dynamic warm-up performed with a vest weighted with 2% of body mass may be the most effective warm-up protocol for enhancing jumping performance in high school female athletes.
PMCID: PMC1748418  PMID: 17273458
adolescents; static stretching; potentiation; power
3.  Short Durations of Static Stretching when Combined with Dynamic Stretching do not Impair Repeated Sprints and Agility 
This study aimed to compare the effect of different static stretching durations followed by dynamic stretching on repeated sprint ability (RSA) and change of direction (COD). Twenty-five participants performed the RSA and COD tests in a randomized order. After a 5 min aerobic warm up, participants performed one of the three static stretching protocols of 30 s, 60 s or 90 s total duration (3 stretches x 10 s, 20 s or 30 s). Three dynamic stretching exercises of 30 s duration were then performed (90 s total). Sit-and-reach flexibility tests were conducted before the aerobic warm up, after the combined static and dynamic stretching, and post- RSA/COD test. The duration of static stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit-and-reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001). However there were no significant differences in RSA and COD performance between the 3 stretching conditions. The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects. Furthermore, the short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments.
Key pointsThe duration of combined static and dynamic stretching had a positive effect on flexibility with 36.3% and 85.6% greater sit and reach scores with the 60 s and 90 s static stretching conditions respectively than with the 30 s condition (p ≤ 0.001).No significant differences in RSA and COD between the 3 stretching conditions.The lack of change in RSA and COD might be attributed to a counterbalancing of static and dynamic stretching effects.The short duration (≤ 90 s) static stretching may not have provided sufficient stimulus to elicit performance impairments.
PMCID: PMC3761850  PMID: 24149890
Flexibility; agility; running; stretch duration; stretch intensity
4.  The differential effects of a complex protein drink versus isocaloric carbohydrate drink on performance indices following high-intensity resistance training: a two arm crossover design 
Background
Post-workout nutrient timing and macronutrient selection are essential for recovery, glycogen replenishment and muscle protein synthesis (MPS). Performance repeatability, particularly after strenuous activity, can be influenced by substrate availability, recovery markers and perceived rate of exertion. This study compared the differential effects of a complex protein ready-to-drink beverage (VPX) and isocaloric carbohydrate beverage (iCHO) on performance—agility T-test, push-up test, 40-yard sprint, and rate of perceived exertion (RPE), following high-intensity resistance training (HIRT).
Methods
In a randomized, double blind two-arm crossover controlled trial, 15 subjects performed a 15–18 minute (2:1 work to rest) HIRT and then immediately drank one of the two treatments. After a 2-hour fast, subjects returned to execute the field tests and report RPE. The protocol was repeated one week later with the other treatment.
Results
There were no significant main effect differences in the agility T-test (p = 0.83), push-up (p = 0.21) sprint (p = 0.12), average agility RPE (p = 0.83), average push-up RPE (p = 0.81) or average sprint RPE (p = 0.66) between the two trials and the two treatments. The multivariate analysis yielded a cumulative significant interaction effect amongst the three performance variables after consuming VPX (p < 0.01). These results suggest a complex protein beverage is a better post-workout choice compared to an isocaloric carbohydrate beverage for repeated performance for activities that require multiple energy demands and athletic skills; however, this outcome was not observed for each single performance event or RPE.
Conclusion
When considering the collective physical effects of the agility T-test, push-up and sprint tests, a complex protein beverage may provide a recovery advantage as it relates to repeated-bout performance compared to an iCHO-only beverage. Additional research examining the chronic effects of post-exercise protein versus iCHO beverages on performance repeatability, particularly in special populations (e.g. tactical and elite athletes), is warranted to further develop these findings.
doi:10.1186/1550-2783-10-31
PMCID: PMC3685561  PMID: 23758838
Isocaloric carbohydrate; Protein drink/beverage; Performance; Repeated-bout; Nutrient timing
5.  Acute Effects of Two Different Warm-Up Protocols on Flexibility and Lower Limb Explosive Performance in Male and Female High Level Athletes 
This study examined the effects of two different warm-up protocols on lower limb power and flexibility in high level athletes. Twenty international level fencers (10 males and 10 females) performed two warm-up protocols that included 5-min light jogging and either short (15s) or long (45s) static stretching exercises for each of the main leg muscle groups (quadriceps, hamstrings and triceps surae), followed by either 3 sets of 3 (short stretching treatment), or 3 sets of 5 tuck jumps (long stretching treatment), in a randomized crossover design with one week between treatments. Hip joint flexion was measured with a Lafayette goniometer before and after the 5-min warm-up, after stretching and 8 min after the tuck jumps, while counter movement jump (CMJ) performance was evaluated by an Ergojump contact platform, before and after the stretching treatment, as well as immediately after and 8 minutes after the tuck jumps. Three way ANOVA (condition, time, gender) revealed significant time (p < 0.001) and gender (p < 0.001) main effects for hip joint flexion, with no interaction between factors. Flexibility increased by 6. 8 ± 1.1% (p < 0.01) after warm-up and by another 5.8 ± 1.6% (p < 0.01) after stretching, while it remained increased 8 min after the tuck jumps. Women had greater ROM compared with men at all time points (125 ± 8° vs. 94 ± 4° p<0.01 at baseline), but the pattern of change in hip flexibility was not different between genders. CMJ performance was greater in men compared with women at all time points (38.2 ± 1.9 cm vs. 29.8 ± 1.2 cm p < 0.01 at baseline), but the percentage of change CMJ performance was not different between genders. CMJ performance remained unchanged throughout the short stretching protocol, while it decreased by 5.5 ± 0.9% (p < 0.01) after stretching in the long stretching protocol However, 8 min after the tuck jumps, CMJ performance was not different from the baseline value (p = 0.075). In conclusion, lower limb power may be decreased after long periods of stretching, but performance of explosive exercises may reverse this phenomenon.
Key points
Stretching of the main leg muscle groups for 45 s results in a relatively large decrease (by 5.5%) in subsequent jumping performance
Stretching of the main leg muscle groups for only 15 s results in an increase in flexibility similar to that of the longer duration stretching (by 12.6%), with no change in subsequent jumping performance
Performance of a PAP exercise such as tuck jumps may reverse the negative effects of long duration stretching on leg muscle power. However, jumping performance is not increased above baseline
Speed/power athletes should be advised against using long duration stretching. The number of repetitions of a PAP exercise such as the tuck jumps, should be further examined in order to induce an increase in explosive performance during competition
PMCID: PMC3763313  PMID: 24150077
Countermovement jump; stretching; post-activation potentiation; fencing
6.  The Effect of Acute Vibration Exercise on Short-Distance Sprinting and Reactive Agility 
Vibration exercise (VbX) has been a popular modality to enhancing physical performance, where various training methods and techniques have been employed to improve immediate and long-term sprint performance. However, the use of acute side-alternating VbX on sprint and agility performance remains unclear. Eight female athletes preformed side-alternating vibration exercise (VbX) and control (no VbX) in a cross over randomised design that was conducted one week apart. After performing a warm-up, the athletes undertook maximal 5m sprints and maximal reactive agility sprints (RAT), this was followed by side-alternating VbX (26 Hz, 6mm) or control (no VbX). Immediately following the intervention, post-sprint tests and RAT were performed. There was a significant treatment effect but there was no time effect (pre vs. post) or interaction effect for sprint and RAT; however, side-alternating VbX did not compromise sprint and agility performance.
Key PointsAcute VbX could be beneficial for the acceleration phase (1.5m) of a short-distance sprint.Acute VbX does not have positive influence on short-distance (3m & 5m) sprint performance.Acute VbX does not enhance reactive agility performance.
PMCID: PMC3772594  PMID: 24149157
Explosive power; speed; postactivation potentiation; warm-up
7.  A pilot study on the effects of pre‐event manipulation on jump height and running velocity 
British Journal of Sports Medicine  2006;40(11):947-949.
Purpose
To compare changes in jump height and running velocity with and without pre‐event high‐velocity, low‐amplitude manipulation (HVLA).
Methods
A crossover study design with elite healthy athletes was used. After a 15 min warm‐up, the subjects were tested for countermovement jump height (CMJ) and flying 40 m sprint time (SPRINT). A sport chiropractor then evaluated each subject. Subjects were randomised to either HVLA (applied to joints based on examination) or placebo (simulated performance‐enhancement stickers). They then rested for 60 min, performed another 15 min warm‐up, and were retested. The protocol was repeated 48 h later with the alternative intervention. The mean of two sprints and three jumps were analysed, as well as peak performances. The sample size was based on prior results from the effects of stretching.
Results
19 subjects involved in sprint sports were enrolled; two were too sore to participate on day 2, and one could only participate in the jump (all had HVLA on day 1). Of the 17 participants analysed, seven were female, age range was 19–35, and 17 were national or world‐class athletes. The ranges for baseline measures were: SPRINT 4.1–5.5 s; CMJ 47.4–92.7 cm. Overall, the greater than expected variability in this pilot study led to the study being underpowered. Subjects tended to perform better after HVLA for both CMJ and SPRINT (both mean and peak results), but none of the results were statistically significant (p  =  0.30–0.61).
Conclusion
Although the larger than expected variability in the pilot study means that the observed clinically relevant differences were not statistically significant, the direction and magnitude of the changes associated with HVLA suggest that it may be beneficial. That said, the increased soreness after HVLA suggests that it may be detrimental. HVLA warrants further study.
doi:10.1136/bjsm.2006.029439
PMCID: PMC2465028  PMID: 16954128
performance enhancement; elite athlete; crossover; manipulation
8.  Acute Effects of Pre-Event Lower Limb Massage on Explosive and High Speed Motor Capacities and Flexibility 
The aim of this study was to examine the acute effects of pre- performance lower limb massage after warm-up on explosive and high-speed motor capacities and flexibility. Twenty-four physically active healthy Caucasian male subjects volunteered to participate in this study. All subjects were from a Physical Education and Sport Department in a large university in Turkey. The study had a counterbalanced crossover design. Each of the subjects applied the following intervention protocols in a randomised order; (a) massage, (b) stretching, and (c) rest. Before (pre) and after (post) each of the interventions, the 10 meter acceleration (AS), flying start 20 meter sprint (FS), 30 meter sprint from standing position (TS), leg reaction time (LR), vertical jump (VJ) and sit & reach (SR) tests were performed. A Wilcoxon’s signed rank test was used to compare before and after test values within the three interventions (massage, stretching and rest). The data showed a significant worsening, after massage and stretching interventions, in the VJ, LR (only in stretching intervention), AS and TS tests (p < 0.05), and significant improvement in the SR test (p < 0.05). In contrast, the rest intervention led only to a significant decrement in TS performance (p < 0.05). In conclusion, the present findings suggest that performing 10 minute posterior and 5 minute anterior lower limb Swedish massage has an adverse effect on vertical jump, speed, and reaction time, and a positive effect on sit and reach test results.
Key pointsPerforming 10 minute posterior and 5 minute anterior lower limb Swedish massages has an adverse affect on vertical jump, speed, and reaction time and a positive effect on sit and reach test results.According to the present results, long duration massage should not be recommended for warm-ups.Larger subject pools are needed to verify these events.
PMCID: PMC3761914  PMID: 24149965
Massage; warm-up; performance; stretching
9.  Attentional and visual demands for sprint performance in non-fatigued and fatigued conditions: reliability of a repeated sprint test 
Background
Physical performance measures are widely used to assess physical function, providing information about physiological and biomechanical aspects of motor performance. However they do not provide insight into the attentional and visual demands for motor performance. A figure-of-eight sprint test was therefore developed to measure the attentional and visual demands for repeated-sprint performance. The aims of the study were: 1) to assess test-retest reliability of the figure-of-eight sprint test, and 2) to study the attentional and visual demands for sprint performance in a non-fatigued and fatigued condition.
Methods
Twenty-seven healthy athletes were included in the study. To determine test-retest reliability, a subgroup of 19 athletes performed the figure-of-eight sprint test twice. The figure-of-eight sprint test consisted of nine 30-second sprints. The sprint test consisted of three test parts: sprinting without any restriction, with an attention-demanding task, and with restricted vision. Increases in sprint times with the attention-demanding task or restricted vision are reflective of the attentional and visual demands for sprinting. Intraclass correlation coefficients (ICCs) and mean difference between test and retest with 95% confidence limits (CL) were used to assess test-retest reliability. Repeated-measures ANOVA were used for comparisons between the sprint times and fatigue measurements of the test parts in both a non-fatigued and fatigued condition.
Results
The figure-of-eight sprint test showed good test-retest reliability, with ICCs ranging from 0.75 to 0.94 (95% CL: 0.40-0.98). Zero lay within the 95% CL of the mean differences, indicating that no bias existed between sprint performance at test and retest. Sprint times during the test parts with attention-demanding task (P = 0.01) and restricted vision (P < 0.001) increased significantly compared to the base measurement. Furthermore the sprint times and fatigue measurements increased significantly in fatigued condition. There was a significant interaction effect between test part and level of fatigue (P = 0.03).
Conclusions
High ICCs and the absence of systematic variation indicate good test-retest reliability of the figure-of-eight sprint test. The attentional and visual demands for sprint performance, in both a non-fatigued and fatigued condition, can be measured in healthy team-sport athletes with the figure-of-eight sprint test.
doi:10.1186/1471-2474-11-84
PMCID: PMC3003243  PMID: 20438646
10.  The Acute Effects of Unilateral Ankle Plantar Flexors Static- Stretching on Postural Sway and Gastrocnemius Muscle Activity During Single-Leg Balance Tasks 
The aim of this study was to investigate the acute effects of unilateral ankle plantar flexors static- stretching on surface electromyography (sEMG) and the center of pressure (COP) during a single-leg balance task in both lower limbs. Fourteen young healthy, non-athletic individuals performed unipodal quiet standing for 30s before and after (stretched limb: immediately post-stretch, 10 and 20 minutes and non-stretched limb: immediately post-stretch) a unilateral ankle plantar flexor static- stretching protocol [6 sets of 45s/15s, 70-90% point of discomfort (POD)]. Postural sway was described using the COP area, COP speed (antero-posterior and medio-lateral directions) and COP frequency (antero-posterior and medio-lateral directions). Surface EMG (EMG integral [IEMG] and Median frequency[FM]) was used to describe the muscular activity of gastrocnemius lateralis. Ankle dorsiflexion passive range of motion increased in the stretched limb before and after the static-stretching protocol (mean ± SD: 15.0° ± 6.0 and 21.5° ± 7.0 [p < 0.001]). COP area and IEMG increased in the stretch limb between pre-stretching and immediately post-stretching (p = 0.015 and p = 0.036, respectively). In conclusion, our static- stretching protocol effectively increased passive ankle ROM. The increased ROM appears to increase postural sway and muscle activity; however these finding were only a temporary or transient effect.
Key PointsThe postural control can be affected by static- stretching protocol.The lateral gastrocnemius muscle action was increased after the static- stretching protocol.The static- stretching effects remain for less than 10 minutes.
PMCID: PMC4126293  PMID: 25177183
Balance; postural stability; stabilometry; motor control
11.  Stretching Before and After Exercise: Effect on Muscle Soreness and Injury Risk 
Journal of Athletic Training  2005;40(3):218-220.
Reference: Herbert RD, Gabriel M. Effects of stretching before and after exercise on muscle soreness and risk of injury: systematic review. BMJ. 2002;325:468.
Clinical Question: Among physically active individuals, does stretching before and after exercise affect muscle soreness and risk of injury?
Data Sources: Studies were identified by searching MEDLINE (1966–February 2000), EMBASE (1988–February 2000), CINAHL (1982–1999), SPORT Discus (1949–1999), and PEDro (to February 2000). I searched the reference lists of identified studies manually until no further studies were identified. The search terms stretch, exercise, warm-up, and cool down were used in all databases except MEDLINE. In MEDLINE, an optimized OVID search strategy was used. This strategy included the terms searched in the other databases as well as terms such as flexibility, athletic injuries, sports, soreness, and muscle.
Study Selection: The search was limited to English-language articles obtained from the electronic searches and the subsequent manual searches. This review included randomized or quasirandomized investigations that studied the effects of any stretching technique, before or after exercise, on delayed-onset muscle soreness, risk of injury, or athletic performance. Studies were included only if stretching occurred immediately before or after exercising.
Data Extraction: Data extraction and assessment of study quality were well described. The principal outcome measures were measurements of muscle soreness and indices of injury risk. Results from the soreness studies were pooled by converting the numeric scores to percentages of the maximum possible score. These data were then reported as millimeters on a 100-mm visual analogue scale. Results of comparable studies were pooled using a fixed-effects model meta-analysis. Survival analysis using a Cox regression model was calculated on the time-to-event (injury) data.
Main Results: The total number of articles identified using the search criteria was not provided; however, 5 studies on stretching and muscle soreness met inclusion and exclusion criteria. All of the studies meeting the criteria employed static stretching. One group reported the findings from 2 experiments, resulting in 6 studies meeting the inclusion and exclusion criteria. For the risk of injury, 2 studies, both investigating lower extremity injury risk in army recruits undergoing 12 weeks of basic training, met inclusion and exclusion criteria. On the basis of the PEDro scale, the methodologic quality of the studies included in the review was moderate (range, 2–7 of 10), with a mean of 4.1. For the studies on muscle soreness, 3 groups evaluated postexercise stretching, whereas 2 evaluated preexercise stretching. The participant characteristics from the 5 studies were noted to be reasonably homogeneous. Subjects in all studies were healthy young adults between the ages of 18 and 40 years (inclusive). For all studies but one, total stretching time per session ranged from 300 to 600 seconds. The exception was one study in which total stretching time was 80 seconds. Data from 77 subjects were pooled for the meta-analysis of muscle soreness outcomes at 24, 48, and 72 hours after exercising. At 24 hours postexercise, the pooled mean effect of stretching after exercise was −0.9 mm (on a 100-mm scale; negative values favor stretching), with a 95% confidence interval (CI) of −4.4 to 2.6 mm. At 48 hours, the pooled mean effect was 0.3 mm (95% CI = −4.0 to 4.5 mm), whereas at 72 hours, the pooled mean effect was −1.6 mm (95% CI = −5.9 to 2.6 mm). In each of these analyses, the results were not statistically significant in favor of either stretching or not stretching. For the studies on risk of lower extremity injury, the authors provided time-to-event (injury) data from 2630 subjects (65 military trainee platoons). These data were then combined and resulted in the allocation of 1284 subjects to stretching groups and 1346 subjects to control groups. The survival analysis identified a pooled estimate of the all-injuries hazard ratio of 0.95 (ie, a 5% decrease in injury risk; 95% CI = 0.78 to 1.16), which was not statistically significant.
Conclusions: The data on stretching and muscle soreness indicate that, on average, individuals will observe a reduction in soreness of less than 2 mm on a 100-mm scale during the 72 hours after exercise. With respect to risk of injury, the combined risk reduction of 5% indicates that the stretching protocols used in these studies do not meaningfully reduce lower extremity injury risk of army recruits undergoing military training.
PMCID: PMC1250267  PMID: 16284645
12.  Organ failure and tight glycemic control in the SPRINT study 
Critical Care  2010;14(4):R154.
Introduction
Intensive care unit mortality is strongly associated with organ failure rate and severity. The sequential organ failure assessment (SOFA) score is used to evaluate the impact of a successful tight glycemic control (TGC) intervention (SPRINT) on organ failure, morbidity, and thus mortality.
Methods
A retrospective analysis of 371 patients (3,356 days) on SPRINT (August 2005 - April 2007) and 413 retrospective patients (3,211 days) from two years prior, matched by Acute Physiology and Chronic Health Evaluation (APACHE) III. SOFA is calculated daily for each patient. The effect of the SPRINT TGC intervention is assessed by comparing the percentage of patients with SOFA ≤5 each day and its trends over time and cohort/group. Organ-failure free days (all SOFA components ≤2) and number of organ failures (SOFA components >2) are also compared. Cumulative time in 4.0 to 7.0 mmol/L band (cTIB) was evaluated daily to link tightness and consistency of TGC (cTIB ≥0.5) to SOFA ≤5 using conditional and joint probabilities.
Results
Admission and maximum SOFA scores were similar (P = 0.20; P = 0.76), with similar time to maximum (median: one day; IQR: [1,3] days; P = 0.99). Median length of stay was similar (4.1 days SPRINT and 3.8 days Pre-SPRINT; P = 0.94). The percentage of patients with SOFA ≤5 is different over the first 14 days (P = 0.016), rising to approximately 75% for Pre-SPRINT and approximately 85% for SPRINT, with clear separation after two days. Organ-failure-free days were different (SPRINT = 41.6%; Pre-SPRINT = 36.5%; P < 0.0001) as were the percent of total possible organ failures (SPRINT = 16.0%; Pre-SPRINT = 19.0%; P < 0.0001). By Day 3 over 90% of SPRINT patients had cTIB ≥0.5 (37% Pre-SPRINT) reaching 100% by Day 7 (50% Pre-SPRINT). Conditional and joint probabilities indicate tighter, more consistent TGC under SPRINT (cTIB ≥0.5) increased the likelihood SOFA ≤5.
Conclusions
SPRINT TGC resolved organ failure faster, and for more patients, from similar admission and maximum SOFA scores, than conventional control. These reductions mirror the reduced mortality with SPRINT. The cTIB ≥0.5 metric provides a first benchmark linking TGC quality to organ failure. These results support other physiological and clinical results indicating the role tight, consistent TGC can play in reducing organ failure, morbidity and mortality, and should be validated on data from randomised trials.
doi:10.1186/cc9224
PMCID: PMC2945138  PMID: 20704712
13.  Effect of Pre-Cooling on Repeat-Sprint Performance in Seasonally Acclimatised Males During an Outdoor Simulated Team-Sport Protocol in Warm Conditions 
Whether precooling is beneficial for exercise performance in warm climates when heat acclimatised is unclear. The purpose of this study was to determine the effect of precooling on repeat-sprint performance during a simulated team-sport circuit performed outdoors in warm, dry field conditions in seasonally acclimatised males (n = 10). They performed two trials, one with precooling (PC; ice slushy and cooling jacket) and another without (CONT). Trials began with a 30-min baseline/cooling period followed by an 80 min repeat-sprint protocol, comprising 4 x 20-min quarters, with 2 x 5-min quarter breaks and a 10-min half-time recovery/cooling period. A clear and substantial (negative; PC slower) effect was recorded for first quarter circuit time. Clear and trivial effects were recorded for overall circuit time, third and fourth quarter sprint times and fourth quarter best sprint time, otherwise unclear and trivial effects were recorded for remaining performance variables. Core temperature was moderately lower (Cohen's d=0.67; 90% CL=-1.27, 0.23) in PC at the end of the precooling period and quarter 1. No differences were found for mean skin temperature, heart rate, thermal sensation, or rating of perceived exertion, however, moderate Cohen's d effect sizes suggested a greater sweat loss in PC compared with CONT. In conclusion, repeat- sprint performance was neither clearly nor substantially improved in seasonally acclimatised players by using a combination of internal and external cooling methods prior to and during exercise performed in the field in warm, dry conditions. Of practical importance, precooling appears unnecessary for repeat-sprint performance if athletes are seasonally acclimatised or artificially acclimated to heat, as it provides no additional benefit.
Key PointsPre-cooling did not improve repeated sprint performance during a prolonged team-sport circuit in field conditions.If individuals are already heat acclimatised/acclimated, pre-cooling is unnecessary for performance enhancement.Acclimation/acclimatisation seems to be the more powerful method for protecting against heat strain.
PMCID: PMC3772603  PMID: 24149166
Cooling jacket; ice slushy; core temperature; 20 m sprint
14.  The influence of commercially-available carbohydrate and carbohydrate-protein supplements on endurance running performance in recreational athletes during a field trial 
Background
It is recommended that endurance athletes consume carbohydrate (CHO) supplements, providing 6-8% CHO concentration, during exercise > 60 minutes to improve athletic performance. Recently research has compared carbohydrate-protein (CHO-P) supplementation to the traditionally used CHO supplementation during endurance exercise, following these supplementation recommendations, in controlled settings, but not under simulated applied conditions such as a field trial. Therefore, the purpose of the present investigation was to test CHO and CHO-P supplementation under applied conditions such that commercially-available isocaloric (CHO-P & double-carbohydrate [CHO-CHO]) and isocarbohydrate (CHO-P & CHO) supplements were compared to a placebo (PLA), within an outdoor running field trial > 60 minutes in order to asses their influence on endurance performance.
Methods
Twelve male recreational runners completed four, 19.2 km runs, where they were instructed to run at a pace similar to race pace including a final sprint to the finish, which in this case was the final two laps of the course (1.92 km). Supplementation was provided before the start and in 4 km increments. Performance was measured by time to complete the 19.2 km run and last 1.92 km sprint.
Results
Analyses found no difference between supplements in time to complete the 19.2 km run (PLA = 88.6 ± 11.6 min, CHO = 89.1 ± 11.3 min, CHO-P = 89.1 ± 11.8 min, CHO-CHO = 89.6 ± 11.9 min) or last 1.92 km sprint to the finish (PLA = 8.3 ± 1.2 min, CHO = 8.2 ± 1.2 min, CHO-P = 8.2 ± 1.2 min, CHO-CHO = 8.4 ± 1.5 min).
Conclusions
When following recommendation for supplementation within a field trial, commercially available CHO and CHO-P supplements do not appear to enhance performance in male recreational runners.
doi:10.1186/1550-2783-10-17
PMCID: PMC3614480  PMID: 23537142
Field experiment; Endurance running; Sport drinks; Carbohydrate-protein
15.  Should Athletes Return to Activity After Cryotherapy? 
Journal of Athletic Training  2014;49(1):95-96.
Reference/Citation
Bleakley CM, Costello JT, Glasgow PD. Should athletes return to sport after applying ice? A systematic review of the effect of local cooling on functional performance. Sports Med. 2012; 42(1):69–87.
Clinical Question
Does local tissue cooling affect immediate functional performance outcomes in a sport situation?
Data Sources
Studies were identified by searching MEDLINE, the Cochrane Central Register of Controlled Trials, and EMBASE, each from the earliest available record through April 2011. Combinations of 18 medical subheadings or key words were used to complete the search.
Study Selection
This systematic review included only randomized controlled trials and crossover studies published in English that examined human participants who were treated with a local cooling intervention. At least 1 functional performance outcome that was measured before and after a cooling intervention had to be reported. Excluded were studies using whole-body cryotherapy or cold-water immersion above the waist and studies that measured strength or force production during evoked muscle contraction.
Data Extraction
Data were extracted by 2 authors using a customized form to evaluate relevant data on study design, eligibility criteria, detailed characteristics of cooling protocols, comparisons, and outcome measures. Disagreement was resolved by consensus or third-party adjudication. To perform an intent-to-treat analysis when possible, data were extracted according to the original allocation groups, and losses to follow-up were noted. The review authors were not blinded to the study author, institution, or journal. For each study, mean differences or standardized mean differences and 95% confidence intervals were calculated for continuous outcomes using RevMan (version 5.1; The Nordic Cochrane Centre, Copenhagen, Denmark). Treatment effects were based on between-groups comparisons (cryotherapy versus control) using postintervention outcomes or within-group comparisons (precryotherapy versus postcryotherapy). If continuous data were missing standard deviations, other statistics including confidence intervals, standard error, t values, P values, or F values were used to calculate the standard deviation. The Cochrane risk-of-bias tool was used to assess the methodologic quality of included studies. Each study was evaluated for sequence generation, allocation concealment, assessor blinding, and incomplete outcome data. Studies were graded as low or high based on the criteria met, but the risk of bias across the studies was consistently high, so meaningful subgroup classifications were not possible. Differences in study quality and intervention details, including duration of cryotherapy interventions and time periods after intervention before follow-up, were potential sources of bias and considered for a subgroup analysis.
Main Results
Using the search criteria, the authors originally identified 1449 studies. Of these, after title and abstract review, 99 studies were deemed potentially relevant and kept for further analysis (1350 studies were excluded). Of the 99 potentially relevant studies, 35 were included in the final review (64 studies were excluded), with relevant outcomes of strength, power, vertical jump, endurance, agility, speed, performance accuracy, and dexterity reported. The 64 excluded studies were rejected due to intervention relevancy, outcome relevancy, and non-English language. In the 35 studies meeting the inclusion criteria, 665 healthy participants were assessed. Muscle strength (using an isokinetic dynamometer, cable tensiometer, strain-gauge device, or load cell) was assessed in 25 studies, whole-body exercise (vertical jump height, power, timed hop test, sprint time, and time taken to complete running-based agility tests, including carioca runs, shuttle sprints, T-shuttle, and cocontraction tests) was assessed in 6, performance accuracy (throwing or shooting) was assessed in 2, and hand dexterity was assessed in 2. Outcomes before and immediately after cryotherapy intervention were reported in all studies; additional outcome assessments at times ranging from 5 to 180 minutes postintervention were recorded in 11 studies. The review authors reported a high risk of bias: selection bias (poor randomization and concealment of group allocation), performance and detection bias (poor blinding of assessors), and attrition bias (incomplete data). Because of the diversity of studies, particularly with respect to cryotherapy protocols and the potential for rewarming before the posttest, the effects of cryotherapy on functional performance were mixed. From the included studies, the authors concluded that cryotherapy treatment reduced upper and lower extremity muscle strength immediately after cryotherapy. However, increases in force output after cryotherapy were reported in 5 studies. Regardless of the effect of cryotherapy on strength, the clinical meaningfulness of most of the data may not be important due to variability and small effects. Studies reporting outcomes of muscle endurance resulted in conflicting evidence: endurance increased immediately after cryotherapy in 6, whereas muscle endurance decreased in 3 . These conflicting results limit the ability to draw clinically relevant conclusions about the effect of cryotherapy on muscle endurance. The majority of studies evaluating whole-body exercise demonstrated decreases in performance after cryotherapy; these outcomes included vertical jump, sprint, and agility, even when cryotherapy was applied only to a body part. Additionally, cryotherapy appeared to decrease hand dexterity and throwing accuracy immediately after intervention, although an increase in shooting performance postintervention was reported in 1 study .
Conclusions
The authors suggested that the available evidence indicates that athletic performance may be adversely affected when athletes return to play immediately after cryotherapy treatments. Many of the included studies used variable cooling protocols, reflecting differences in time, temperature, and mode of cryotherapy. The majority of the included studies used cryotherapy for at least 20 minutes. However, when considering an immediate return to activity, this cooling duration may not be clinically relevant because cryotherapy applications during practice and competitions usually last less than 20 minutes. When immediate return to activity occurs after cryotherapy, short-duration cold applications or progressive warm-ups should be implemented to prevent a deleterious effect on functional performance.
doi:10.4085/1062-6050-48.3.13
PMCID: PMC3917303  PMID: 23724775
cold modalities; functional performance; strength; endurance
16.  Effects of Combined Foot/Ankle Electromyostimulation and Resistance Training on the In-Shoe Plantar Pressure Patterns during Sprint in Young Athletes 
Several studies have already reported that specific foot/ankle muscle reinforcement strategies induced strength and joint position sense performance enhancement. Nevertheless the effects of such protocols on sprint performance and plantar loading distribution have not been addressed yet. The objective of the study is to investigate the influence of a 5-wk foot/ankle strength training program on plantar loading characteristics during sprinting in adolescent males. Sixteen adolescent male athletes of a national training academy were randomly assigned to either a combined foot/ankle electromyostimulation and resistance training (FAST) or a control (C) group. FAST consisted of foot medial arch and extrinsic ankle muscles reinforcement exercises, whereas C maintained their usual training routine. Before and after training, in-shoe loading patterns were measured during 30-m running sprints using pressure sensitive insoles (right foot) and divided into nine regions for analysis. Although sprint times remained unchanged in both groups from pre- to post- training (3.90 ± 0.32 vs. 3.98 ± 0.46 s in FAST and 3.83 ± 0.42 vs. 3.81 ± 0.44 s in C), changes in force and pressure appeared from heel to forefoot between FAST and C. In FAST, mean pressure and force increased in the lateral heel area from pre- to post- training (67.1 ± 44.1 vs. 82.9 ± 28.6 kPa [p = 0.06]; 25.5 ± 17.8 vs. 34.1 ± 14.3 N [p = 0.05]) and did not change in the medial forefoot (151.0 ± 23.2 vs. 146.1 ± 30.0 kPa; 142.1 ± 29.4 vs. 136.0 ± 33.8; NS). Mean area increased in FAST under the lateral heel from pre- to post- (4.5 ± 1.3 vs. 5.7 ± 1.6 cm2 [p < 0.05]) and remained unchanged in C (5.5 ± 2.8 vs. 5.0 ± 3.0 cm2). FAST program induced significant promising lateral and unwanted posterior transfer of the plantar loads without affecting significantly sprinting performance.
Key pointsWe have evaluated the effects of a foot/ankle strength training program on sprint performance and on related plantar loading characteristics in teenage athletes, and this have not been examined previously.Our results showed no significant pre- to post- changes in sprint performance.This study revealed initially a lateral transfer and secondly a posterior transfer of the plantar loads after the foot/ankle strength training program.
PMCID: PMC3761852  PMID: 24149874
Track and field; medial arch; reinforcement; injury prevention
17.  Duration of Maintained Hamstring Flexibility After a One-Time, Modified Hold-Relax Stretching Protocol 
Journal of Athletic Training  2001;36(1):44-48.
Objective:
Previous research suggests proprioceptive neuromuscular facilitation (PNF) stretching techniques produce greater increases in range of motion than passive, ballistic, or static stretching methods. The purpose of our study was to measure the duration of maintained hamstring flexibility after a 1-time, modified hold-relax stretching protocol.
Design and Setting:
The study had a 1 × 1 mixed-model, repeated-measures design. The independent variables were group (control and experimental) and time (0, 2, 4, 6, 8, 16, and 32 minutes). The dependent variable was hamstring flexibility as measured in degrees of active knee extension with the hip flexed to 90°. Measurements were taken in a preparatory military academy athletic training room.
Subjects:
Thirty male subjects (age, 18.8 ± 0.63 years; height, 185.2 ± 14.2 cm; weight, 106.8 ± 15.7 kg) with limited hamstring flexibility in the right lower extremity were randomly assigned to a control (no-stretch) group or an experimental (stretch) group.
Measurements:
All subjects performed 6 warm-up active knee extensions, with the last repetition serving as the prestretch measurement. The experimental group received 5 modified (no-rotation) hold-relax stretches, whereas the control group rested quietly supine on a table for 5 minutes. Posttest measurements were recorded for both groups at 0, 2, 4, 6, 8, 16, and 32 minutes.
Results:
The repeated-measures analysis of variance revealed a significant group-by-time interaction, a significant main effect for group, and a significant main effect for time. Dunnett post hoc analysis revealed a significant improvement in knee-extension range of motion in the experimental group that lasted 6 minutes after the stretching protocol ended.
Conclusions:
Our findings suggest that a sequence of 5 modified hold-relax stretches produced significantly increased hamstring flexibility that lasted 6 minutes after the stretching protocol ended.
PMCID: PMC155401  PMID: 12937514
active knee-extension test; knee joint range of motion
18.  A TOTAL MOTION RELEASE WARM‐UP IMPROVES DOMINANT ARM SHOULDER INTERNAL AND EXTERNAL ROTATION IN BASEBALL PLAYERS 
Context:
Current literature indicates a correlation between decreased total shoulder range of motion (ROM) and internal rotation (IR) of the dominant arm and increased injury risk in throwers. The optimal method for increasing shoulder ROM, improving performance, and preventing injury is unknown. It is also unknown if treating the non‐dominant arm may affect ROM on the dominant side.
Purpose:
To explore the effect of the Total Motion Release (TMR®) Trunk Twist (TT) and Arm Raise (AR) on IR and external rotation (ER) of the dominant shoulder in baseball players compared to a traditional dynamic warm‐up.
Design:
Cohort study.
Setting:
University athletic training clinic and baseball field.
Participants:
Pitchers (males, n = 10; age, 18.6 ± 1.3) recruited from local baseball teams were randomly assigned two one of two groups: TMR® treatment group (TMRG; n = 5) or traditional warm‐up group (TWG; n = 5).
Interventions:
Baseline IR and ER goniometry range of motion (ROM) measurements were recorded. The TMRG then completed the TMR® exercises and post‐intervention measurements. The TWG completed a traditional static and dynamic warm‐up (e.g., lunges, power skips, sprints, sleeper stretch) and then completed post‐intervention measurements. Following the completion of those measurements, the TWG completed the TMR® Trunk Twist and Arm Raise protocol and had post‐intervention measurements recorded once more.
Main Outcome Measures:
ROM measures for IR and ER of the dominant shoulder. Alpha level was set at p ≤ 0.05.
Results
Significant differences were present for IR (p = 0.025) and ER (p = 0.014) between the TMRG and the TWG after initial intervention. Significant differences for IR were present in the TWG between baseline and TMR® intervention and traditional warm‐up and TMR® intervention. For the TWG, changes in ER were not statistically significant at baseline, post‐warm‐up, or post‐ TMR® intervention. Significant differences were not present for IR (p = 0.44) or ER (p = 0.23) between groups once TMR® had been completed by both groups.
Conclusions:
TMR® produced larger increases in IR and ER of the throwing shoulder when compared to the TWG. Generalizability is limited, however, by the low number of participants in each group and a potential ceiling effect of attainable ROM gains. Future studies should examine if using a full TMR® treatment process is more beneficial. Additionally, future research should compare TMR® intervention to other warm‐up activities or stretching protocols (e.g. resistance tubing, weighted balls) and examine its effect across other variables (e.g., injury rates, throwing velocity).
Level of Evidence:
Clinical Evidence Based Level 2b
PMCID: PMC4127513  PMID: 25133079
Baseball; Pitcher; Position Player; Total Motion Release®; Warm‐Up
19.  The Effects of Different Stretching Techniques of the Quadriceps Muscles on Agility Performance in Female Collegiate Soccer Athletes: A Pilot Study 
Background
Stretching has long been an integral component of pre-performance activities for a multitude of athletic endeavors. Previous research has demonstrated that stretching may have detrimental effects on performance. Specific knowledge of the precise effects of stretching may influence the decision to appropriately apply stretching techniques in the sport and therapeutic settings.
Objective
The purpose of this pilot study was to examine the effects of static stretching, proprioceptive neuromuscular facilitation (contract-relax) stretching, and no stretching of the quadriceps muscle group on agility performance.
Methods
Twelve healthy, female, collegiate soccer players aged 18 – 25 performed one of the three stretching protocols (static, contract-relax, no stretch) and the agility test (T-test) on three non-consecutive days. Agility times were recorded and compared based on stretching technique and day that each test was performed.
Results
No significant difference was found among the means of the different stretching techniques. The t-test agility performance times were as follows: control, =9.7 seconds; static stretch, =9.73 seconds; and contract-relax, =9.62 seconds.
Conclusion
The results of this study suggest that agility performance may be independent of stretching technique of the quadriceps performed in female collegiate soccer athletes. It is recommended that female soccer athletes about to engage in agility activity may perform either no stretch, static stretch, or contract-relax stretching according to individual preference.
PMCID: PMC2953305  PMID: 21509139
agility performance; contract-relax stretching; static-stretching; female athletes
20.  Ice Bag Application, Active Warm-Up, and 3 Measures of Maximal Functional Performance 
Journal of Athletic Training  2006;41(4):364-370.
Context: Research into the effects of ice on neuromuscular performance is limited, and the results sometimes conflict.
Objective: To examine the effects of ice bag application to the anterior thigh and active warm-up on 3 maximal functional performance tests.
Design: A 2 × 2 repeated-measures design with 4 randomly assigned treatment conditions: (1) no ice/no warm-up, (2) ice/ no warm-up, (3) no ice/warm-up, and (4) ice/warm-up.
Setting: Gymnasium with a wooden floor.
Patients or Other Participants: Twenty-four active, uninjured men, 18 to 24 years of age.
Intervention(s): For the ice application, we applied an ice bag with compression to the anterior thigh for 20 minutes. Warm-up (6.5 minutes) consisted of 3 minutes of jogging, 3 minutes of stretching, and ten 2-legged vertical jumps.
Main Outcome Measure(s): Maximal performance of 3 functional fitness tests: single-leg vertical jump height, shuttle run time, and 40-yd (36.58-m) sprint time.
Results: Significant main effects were noted for both ice and warm-up for all functional tests, with a significant interaction (ice × warm-up) for the 40-yd sprint test. Ice bag application negatively affected performance on all 3 functional tests; warm-up significantly improved posticing performance. High-intensity maximal performance after ice bag application almost returned to the no ice/no warm-up pretreatment levels with the addition of active warm-up and time.
Conclusions: Ice bag application negatively affected performance of maximal high-intensity functional tests. Active warm-up and time for muscle warming after ice bag application decreased the detrimental effects of icing on functional performance.
PMCID: PMC1748415  PMID: 17273459
cryotherapy; modalities; agility; sprint; vertical jump
21.  Significant Molecular and Systemic Adaptations after Repeated Sprint Training in Hypoxia 
PLoS ONE  2013;8(2):e56522.
While intermittent hypoxic training (IHT) has been reported to evoke cellular responses via hypoxia inducible factors (HIFs) but without substantial performance benefits in endurance athletes, we hypothesized that repeated sprint training in hypoxia could enhance repeated sprint ability (RSA) performed in normoxia via improved glycolysis and O2 utilization. 40 trained subjects completed 8 cycling repeated sprint sessions in hypoxia (RSH, 3000 m) or normoxia (RSN, 485 m). Before (Pre-) and after (Post-) training, muscular levels of selected mRNAs were analyzed from resting muscle biopsies and RSA tested until exhaustion (10-s sprint, work-to-rest ratio 1∶2) with muscle perfusion assessed by near-infrared spectroscopy. From Pre- to Post-, the average power output of all sprints in RSA was increased (p<0.01) to the same extent (6% vs 7%, NS) in RSH and in RSN but the number of sprints to exhaustion was increased in RSH (9.4±4.8 vs. 13.0±6.2 sprints, p<0.01) but not in RSN (9.3±4.2 vs. 8.9±3.5). mRNA concentrations of HIF-1α (+55%), carbonic anhydrase III (+35%) and monocarboxylate transporter-4 (+20%) were augmented (p<0.05) whereas mitochondrial transcription factor A (−40%), peroxisome proliferator-activated receptor gamma coactivator 1α (−23%) and monocarboxylate transporter-1 (−36%) were decreased (p<0.01) in RSH only. Besides, the changes in total hemoglobin variations (Δ[tHb]) during sprints throughout RSA test increased to a greater extent (p<0.01) in RSH. Our findings show larger improvement in repeated sprint performance in RSH than in RSN with significant molecular adaptations and larger blood perfusion variations in active muscles.
doi:10.1371/journal.pone.0056522
PMCID: PMC3577885  PMID: 23437154
22.  Interaction of Central and Peripheral Factors during Repeated Sprints at Different Levels of Arterial O2 Saturation 
PLoS ONE  2013;8(10):e77297.
Purpose
To investigate the interaction between the development of peripheral locomotor muscle fatigue, muscle recruitment and performance during repeated-sprint exercise (RSE).
Method
In a single-blind, randomised and cross-over design, ten male team-sport athletes performed two RSE (fifteen 5-s cycling sprints interspersed with 25 s of rest; power self-selected) in normoxia and in acute moderate hypoxia (FIO2 0.138). Mechanical work, total electromyographic intensity (summed quadriceps electromyograms, RMSsum) and muscle (vastus lateralis) and pre-fontal cortex near-infrared spectroscopy (NIRS) parameters were calculated for every sprint. Blood lactate concentration ([Lac-]) was measured throughout the protocol. Peripheral quadriceps fatigue was assessed via changes in potentiated quadriceps twitch force (ΔQtw,pot) pre- versus post-exercise in response to supra-maximal magnetic femoral nerve stimulation. The central activation ratio (QCAR) was used to quantify completeness of quadriceps activation.
Results
Compared with normoxia, hypoxia reduced arterial oxygen saturation (-13.7%, P=0.001), quadriceps RMSsum (-13.7%, P=0.022), QCAR (-3.3%, P=0.041) and total mechanical work (-8.3%, P=0.019). However, the magnitude of quadriceps fatigue induced by RSE was similar in the two conditions (ΔQtw,pot: -53.5% and -55.1%, P=0.71). The lower cycling performance in hypoxia occurred despite similar metabolic (muscle NIRS parameters and blood [Lac-]) and functional (twitch and M-wave) muscle states.
Conclusion
Results suggest that the central nervous system regulates quadriceps muscle recruitment and, thereby, performance to limit the development of muscle fatigue during intermittent, short sprints. This finding highlights the complex interaction between muscular perturbations and neural adjustments during sprint exercise, and further supports the presence of pacing during intermittent sprint exercise.
doi:10.1371/journal.pone.0077297
PMCID: PMC3796493  PMID: 24155938
23.  Effects of Baseline Levels of Flexibility and Vertical Jump Ability on Performance Following Different Volumes of Static Stretching and Potentiating Exercises in Elite Gymnasts 
This study examined the effects of baseline flexibility and vertical jump ability on straight leg raise range of motion (ROM) and counter-movement jump performance (CMJ) following different volumes of stretching and potentiating exercises. ROM and CMJ were measured after two different warm-up protocols involving static stretching and potentiating exercises. Three groups of elite athletes (10 male, 14 female artistic gymnasts and 10 female rhythmic gymnasts) varying greatly in ROM and CMJ, performed two warm-up routines. One warm-up included short (15 s) static stretching followed by 5 tuck jumps, while the other included long static stretching (30 s) followed by 3x5 tuck jumps. ROM and CMJ were measured before, during and for 12 min after the two warm-up routines. Three-way ANOVA showed large differences between the three groups in baseline ROM and CMJ performance. A type of warm-up x time interaction was found for both ROM (p = 0.031) and CMJ (p = 0.016). However, all athletes, irrespective of group, responded in a similar fashion to the different warm-up protocols for both ROM and CMJ, as indicated from the lack of significant interactions for group (condition x group, time x group or condition x time x group). In the short warm-up protocol, ROM was not affected by stretching, while in the long warm-up protocol ROM increased by 5.9% ± 0.7% (p = 0.001) after stretching. Similarly, CMJ remained unchanged after the short warm-up protocol, but increased by 4.6 ± 0.9% (p = 0.012) 4 min after the long warm- up protocol, despite the increased ROM. It is concluded that the initial levels of flexibility and CMJ performance do not alter the responses of elite gymnasts to warm-up protocols differing in stretching and potentiating exercise volumes. Furthermore, 3 sets of 5 tuck jumps result in a relatively large increase in CMJ performance despite an increase in flexibility in these highly-trained athletes.
Key PointsThe initial levels of flexibility and vertical jump ability have no effect on straight leg raise range of motion (ROM) and counter-movement jump performance (CMJ) of elite gymnasts following warm-up protocols differing in stretching and potentiating exercise volumesStretching of the main leg muscle groups for only 15 s has no effect on ROM of elite gymnastsIn these highly-trained athletes, one set of 5 tuck jumps during warm-up is not adequate to increase CMJ performance, while 3 sets of 5 tuck jumps result in a relatively large increase in CMJ performance (by 4.6% above baseline), despite a 5.9% increase in flexibility due to the 30 s stretching exercises
PMCID: PMC3918545  PMID: 24570613
Gymnastics; countermovement jump; stretching; post- activation potentiation
24.  Effect of Static and Dynamic Stretching on the Diurnal Variations of Jump Performance in Soccer Players 
PLoS ONE  2013;8(8):e70534.
Purpose
The present study addressed the lack of data on the effect of different types of stretching on diurnal variations in vertical jump height - i.e., squat-jump (SJ) and countermovement-jump (CMJ). We hypothesized that dynamic stretching could affect the diurnal variations of jump height by producing a greater increase in short-term maximal performance in the morning than the evening through increasing core temperature at this time-of-day.
Methods
Twenty male soccer players (age, 18.6±1.3 yrs; height, 174.6±3.8 cm; body-mass, 71.1±8.6 kg; mean ± SD) completed the SJ and CMJ tests either after static stretching, dynamic stretching or no-stretching protocols at two times of day, 07:00 h and 17:00 h, with a minimum of 48 hours between testing sessions. One minute after warming-up for 5 minutes by light jogging and performing one of the three stretching protocols (i.e., static stretching, dynamic stretching or no-stretching) for 8 minutes, each subject completed the SJ and CMJ tests. Jumping heights were recorded and analyzed using a two-way analysis of variance with repeated measures (3 [stretching]×2 [time-of-day]).
Results
The SJ and CMJ heights were significantly higher at 17:00 than 07:00 h (p<0.01) after the no-stretching protocol. These daily variations disappeared (i.e., the diurnal gain decreased from 4.2±2.81% (p<0.01) to 1.81±4.39% (not-significant) for SJ and from 3.99±3.43% (p<0.01) to 1.51±3.83% (not-significant) for CMJ) after dynamic stretching due to greater increases in SJ and CMJ heights in the morning than the evening (8.4±6.36% vs. 4.4±2.64%, p<0.05 for SJ and 10.61±5.49% vs. 6.03±3.14%, p<0.05 for CMJ). However, no significant effect of static stretching on the diurnal variations of SJ and CMJ heights was observed.
Conclusion
Dynamic stretching affects the typical diurnal variations of SJ and CMJ and helps to counteract the lower morning values in vertical jump height.
doi:10.1371/journal.pone.0070534
PMCID: PMC3734300  PMID: 23940589
25.  Effect of Various Warm-Up Protocols on Jump Performance in College Football Players 
Journal of Human Kinetics  2012;35:127-132.
The purpose of this study was to identify the effects of warm-up strategies on countermovement jump performance. Twenty-nine male college football players (age: 19.4 ± 1.1 years; body height: 179.0 ± 5.1 cm; body mass: 73.1 ± 8.0 kg; % body fat: 11.1 ± 2.7) from the Tuzla University underwent a control (no warm-up) and different warm-up conditions: 1. general warm-up; 2. general warm-up with dynamic stretching; 3. general warm-up, dynamic stretching and passive stretching; 4. passive static stretching; 5. passive static stretching and general warm-up; and, 6. passive static stretching, general warm-up and dynamic stretching. Countermovement jump performance was measured after each intervention or control. Results from one way repeated measures ANOVA revealed a significant difference on warm-up strategies at F (4.07, 113.86) = 69.56, p < 0.001, eta squared = 0.72. Bonferonni post hoc revealed that a general warm-up and a general warm-up with dynamic stretching posted the greatest gains among all interventions. On the other hand, no warm-up and passive static stretching displayed the least results in countermovement jump performance. In conclusion, countermovement jump performance preceded by a general warm-up or a general warm-up with dynamic stretching posted superior gains in countermovement jump performance.
doi:10.2478/v10078-012-0086-5
PMCID: PMC3588691  PMID: 23486654
warm-up; static stretching; dynamic stretching; athletes; vertical jump

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