Niacin supplementation impairs exercise performance.

Several pre-workout supplements contain niacin, although the exercise performance effects of niacin are poorly understood. The purpose of the present study was to examine the performance effects of niacin versus caffeine as a pre-workout supplement. Twenty-five untrained males were recruited to complete three identical ramped aerobic cycling exercise trials. Participants were administered caffeine (CA) at 5 mg/kg body weight, 1000 mg niacin (NI), or a methylcelluloce placebo (PL) supplement prior to each trial. NI treatment induced significantly higher respiratory exchange ratio (RER) during exercise compared to the CA treatment, but not the PL treatment (PL=0.87±0.08, NI=0.91±0.08, CA=0.87±0.08; p=0.02). Similarly, exercise time to exhaustion (in minutes) was significantly different between the NI treatment and the CA treatment, but not the PL treatment (PL=27.45±4.47, NI=26.30±4.91, CA=28.76±4.86; p<0.01). Habitual caffeine use (p=0.16), habitual aerobic exercise (p=0.60), and habitual resistance exercise (p=0.10) did not significantly affect RER. Similarly, habitual caffeine use (p=0.72), habitual aerobic exercise (p=0.08), and habitual resistance exercise (p=0.39) did not significantly affect total work performed. The elevated RER and decreased time to exhaustion in the NI treatment suggests limited lipid availability during exercise and impaired exercise performance.

The Effect of Aspartate and Sodium Bicarbonate Supplementation on Muscle Contractile Properties Among Trained Men.

Farney, TM, MacLellan, MJ, Hearon, CM, Johannsen, NM, and Nelson, AG. The effect of aspartate and sodium bicarbonate supplementation on muscle contractile properties among trained men. J Strength Cond Res 34(3): 763-770, 2020-The focus of this investigation was to examine the effects of aspartate and NaHCO3 supplementation on muscle contractile properties within trained men. Eleven men (21.9 ± 1.5 years) ingested supplementation as 4 conditions all separated by 1 week and included the following: placebo (PLA), L-aspartate (12.5 mg) (ASP), NaHCO3 (0.3 g·kg) (SBC), or combination of ASP and SBC (CBO). For each day of testing, participants performed 1 high-intensity exercise session along with a pre- and postexercise (pre- or postex) isometric mid thigh pull test to measure peak force (PF) production and rate of force development (RFD). Blood was collected for all testing sessions before and after the high-intensity exercise to determine ammonia accumulation (AMM). Exercise sessions consisted of 4 exercises: barbell thrusters, squat jumps, lunge jumps, and forward jumps, with the total amount of work being equated for all 4 exercises across all 4 testing sessions. Participants performed the exercises in the aforementioned order, which was designated as 1 round. Each participant performed 3 rounds, with the work-to-rest ratio being 20-second work, 30-second rest. A 1-minute rest was given between the rounds. There were no treatment effects (p > 0.05) for PF, RFD, or AMM. However, there was a significant main effect for supplement consumption for the total time of work with the ASP, SBC, and CBO treatments having a lower time to completion compared with the PLA treatment. Ammonia was significantly elevated postexercise (p = 0.004), whereas there were no differences from preexercise to postexercise for PF or RFD (p > 0.05). The only significant treatment × time interaction was for RFD (p = 0.03) with CBO increasing postexercise, with the other 3 treatments all decreasing postexercise. The combination of ASP and SBC together may have the potential to reduce fatigue by mitigating the effects of metabolic by-product accumulation.

The Effect of Vinegar Supplementation on High-Intensity Cycling Performance within Recreationally Trained Individuals.

Background and objectives: To investigate the effects of vinegar ingestion upon high-intensity cycle performance in recreationally trained individuals. Materials and methods: Twenty-two participants consumed one of the following in a randomized order on four separate visits: (1) 29 mL of vinegar along with 451 mL of water, (2) 39 g of sucrose along with 441 mL of water, (3) 29 mL of vinegar and 39 g of sucrose along with 412 mL of water, or (4) 480 mL of water alone. For each of the experimental testing sessions, all participants completed in order: (1) high-intensity cycle test 1, (2) fatiguing cycle test, (3) high-intensity cycle test 2, (4) supplement consumption, (5) 90 min rest period, and (6) high-intensity cycle test 3. Total time to exhaustion (TTE) and average heart rate (HR) for each set of sprints was used in analysis. Results: There was no supplement by time interaction or significant main treatment effect observed (p > 0.05) for either TTE or HR. However, there was a main time effect observed, with TTE (p = 0.0001) being lower for cycle test 2 than both cycle test 1 and cycle test 3, and cycle test 3 being lower than cycle test 1. HR (p = 0.0001) was lower for cycle test 3 than both cycle test 1 and cycle test 2, but HR for cycle test 1 did not differ significantly from HR for cycle test 2. Conclusions: The addition of vinegar or sucrose alone, or in combination, was ineffective in improving cycle sprinting TTE when performing three cycle tests.

Visually-guided saccades attenuate postural sway under non-fatigued, fatigued, and stretched states.

Muscular fatigue, which reduces force output and position sense, often leads to increased sway and potential balance impairments. In contrast, visually-guided saccadic eye movements (saccades) can attenuate sway more than fixating gaze on an external target. The goals of this study were to determine whether the use of saccades could reduce the increased postural sway in a fatigued state and to better understand the contributions to fatigue-induced increased sway. We compared the effects of gazing at a fixation point (FP) and performing saccades (SAC) on various spatial and temporal measures of the center of pressure (CoP) while participants stood as still as possible on a force plate. Participants used either a narrow or wide base of support and performed three trials for each eye movement condition (SAC, FP) in three states (non-fatigued-NF, stretched-S, and fatigued-F). Calf raises to exhaustion induced ankle fatigue. Extreme plantar- and dorsi-flexion induced stretch. SAC significantly decreased sway and increased time-series complexity (sample entropy) compared to FP. F increased sway and decreased time-series complexity compared to NF and S states, which were similar. Reduced force production, which accompanies muscle fatigue and stretching, did not account for increased sway associated with acute bouts of ankle muscle fatigue. Increased position sense often associated with muscle stretching likely compensated for any reduced force output for S, while the decreased position sense associated with F probably explained the increased sway in this state. Performing saccadic eye movements during quiet stance can help reduce sway under various states.

Relationship between family history of type 2 diabetes and serum FGF21.

BACKGROUND: Determining predictive markers for the development of type 2 diabetes (T2D), particularly in young individuals, offers immense potential benefits in preventative medicine. Previous research examining serum fibroblast growth factor 21 (FGF21) in humans has revealed equivocal relationships with clinical markers of metabolic dysfunction. However, it is unknown to what extent, if any, first-degree family history of T2D (mother or father of the participant diagnosed with T2D) level affects serum FGF21 levels. The aim of this study was to determine whether in healthy individuals with FH+ (n = 18) and without FH- (n = 17) a family history of T2D affects serum FGF21. MATERIALS AND METHODS: Fasting serum and clinical, metabolic and anthropometric measures were determined using a cross-sectional design. RESULTS: Differences between groups for FGF21 were not significant (FH+ = 266 pg/mL ± 51·4, FH = 180 pg/mL ± 29; Z = 0·97, P = 0·33). Adiponectin values were lower in FH+ (8·81 µg/mL ± 2·14) compared to FH- (10·65 µg/mL ± 1·44; F = 8·83, P = 0·01). Resistin was negatively correlated with FGF21 for all participants (r = -0·38, P = 0·03), but no other clinical, metabolic, or serum markers were predictive for serum FGF21 in FH+ or FH-. CONCLUSIONS: Serum FGF21 is not significantly different between FH+ and FH- in young, healthy individuals. Based upon the data of this pilot study, it is unclear whether serum FGF21 can be used as a stand-alone predictive marker for T2D in healthy subjects.

Emerging Relationships Between Vitamin D Status, Physical Activity Habits, and Immune Indices in College-Aged Females.

It has been determined that individuals who are regularly physically active have more favorable inflammatory profiles; less is known about how vitamin D levels can impact inflammation. This study explored the relationship between inflammatory indices in physically active (PA) and not physically active (NPA) individuals with 25-hydroxyvitamin D (25OHD) concentrations either above or below optimal concentrations. All female subjects (n = 63, age 19 - 35 years) were evaluated for body composition, maximal aerobic capacity (VO2peak), and anaerobic power (Wingate). Blood samples were analyzed for 25OHD and C-reactive protein (CRP), stimulated with lipopolysaccharide (LPS) and assessed for interleukin-6 (IL-6) production, and used for flow cytometric analysis. PA (n = 30) had higher 25OHD levels (45.2 ± 2.7 vs. 17.05 ± 1.4 ng / mL; p = 0.015), higher VO2peak (p < 0.0001), lower body weight (p = 0.039) and lower estimated percent body fat (p = 0.011) compared to NPA (n = 33). PA also had lower LPS-stimulated IL-6 production compared to NPA (p = 0.0163), although there were no differences between resting CRP concentrations. NPA with optimal 25OHD had fewer total monocytes, CD14+CD16-cells, CD14+CD16+ cells, and decreased TLR4 expression on CD14+CD16+ cells compared to NPA with suboptimal 25OHD (< 32 ng / mL). In summary, regular physical activity was associated with higher serum 25OHD, healthier measures of body composition, and reduced stimulated IL-6 production. However, optimal vitamin D status was not associated with anti-inflammatory benefits beyond those which are provided by regular physical activity.

Effect of 12 Weeks of Periodized Resistance Training Upon Total Plasma Adiponectin Concentration in Healthy Young Men.

The effects of resistance training on adiponectin have thus far yielded equivocal results. However, the effect of periodized resistance training on plasma adiponectin in offspring of type 2 diabetic and nondiabetic (ND) parents (first-degree family history) has yet to be determined. Untrained healthy young men with and without a first-degree family history of type 2 diabetes were assigned to an exercise intervention group (E) or an active control group (C). The E group performed a 12-week periodized resistance training program, whereas the C group did not participate in any structured exercise program. Fasting plasma samples were obtained pre- and posttraining. Total plasma adiponectin changed significantly in the E group (33.7 ± 14.7%, p = 0.025) but not in the C group (10.8 ± 19.2%). Offspring of type 2 diabetic parents subjects had significantly greater improvements in plasma adiponectin (69.3 ± 34.8%) compared with ND subjects (-3.2 ± 29.9%, p = 0.046). Regular aerobic exercise was significantly correlated with average plasma adiponectin (r = 0.32), whereas first-degree family history of type 2 diabetes (r = -0.58) and decreases in body fat percentage (r = -0.77) were inversely correlated with average plasma adiponectin. Periodized high-intensity resistance training seems to increase plasma adiponectin, particularly in individuals with a first-degree family history of type 2 diabetes or those who experience a significant loss of fat mass. The direct correlation between regular aerobic exercise and adiponectin further suggests that a combination of aerobic and resistance training yields greater improvements in plasma adiponectin compared with resistance training alone.

Short bouts of high-intensity resistance-style training produce similar reductions in fasting blood glucose of diabetic offspring and controls.

Family history of diabetes (FH) is associated with impaired cardiometabolic function. Aerobic exercise improves insulin sensitivity, though resistance training studies on fasting glucose (FG) in FH are lacking. This study examined the effects of 7 weeks of high-intensity-resistance-focused training (HIRFT), including circuit, core, and plyometric resistance training on FG in FH and matched controls (CON). We hypothesized that HIRFT would reduce FG levels, with greater reductions in CON. Thirty-eight healthy men and women (23.5 ± 2 years; 171 ± 7.4 cm; 71 ± 14 kg) participated in 7 weeks of HIRFT including full-body, plyometric, and core resistance training on alternate days. Fasting glucose was analyzed before and after the 7-week training before and after workouts. One repetition maximum was calculated for bench press, squat, and deadlift before and after training. Body mass index and resting HR remained unchanged. Fasting glucose declined similarly between groups with training (-0.23 ± 0.08 vs. -0.20 ± 0.07 mmol·L, p < 0.01 for FH and CON, respectively), whereas strength increased (kg) (bench: 8.0 ± 1.8, squat: 19.4 ± 4.6, deadlift: 16.4 ± 3.6, overall mean percent increase: 38.9 ± 9.2, p < 0.001). Ten-minute postexercise glucose decreased (-0.65 mmol·L, p = 0.05) with training, with no differences between groups. Changes in FG and strength increase were inversely correlated (r = -0.519, p = 0.05). Strength increased equally between groups. Data indicate that HIRFT reduces FG concentrations similarly in FH and CON, making it effective for improving FG in FH.

Acute stretching increases postural stability in nonbalance trained individuals.

Studies into the relationship between acute stretching and maintenance of postural balance have been inconclusive. It was hypothesized that familiarization with the task and subsequent learning might be involved in the conflicting results. Therefore, this study was to designed determine if a regimen of static stretching exercises after a familiarization period would improve a person's ability to maintain a stabilometer in a neutral position and whether stretching had the same effect on individuals with extensive involvement with balancing tasks. Forty-two college students (21 male, 21 female) and 10 surfers (all male) performed tests on a stabilometer on 2 separate days after 3 days of familiarization. Testing followed either 30 minutes of quiet sitting (nonstretched) or 30 minutes of stretching activities (stretched). Stretching exercises consisted of various assisted and unassisted static stretches of the muscles around the hip, knee, and ankle joints. Improved flexibility after the stretching exercises was demonstrated by significant (p < 0.05) 6.5 ± 2.7 cm (mean ± SD) increase in the sit and reach. Balance time for the students improved significantly by 11.4% (2.0-second increase), but the surfers had no significant change. Thus, stretching improved maintenance of balance perhaps by helping the subjects to eliminate the gross muscle contractions that caused large stabilometer displacements and to replace them with fine muscle contractions that caused little or no stabilometer displacements. However, it appears that experience doing balance tasks supplants any stretching benefit.

A 10-week stretching program increases strength in the contralateral muscle.

It was questioned whether a unilateral stretching program would induce a crosstraining effect in the contralateral muscle. To test this, 13 untrained individuals participated in a 10-week stretching program while 12 other untrained individuals served as a control group. For the experimental group, the right calf muscle was stretched 4 times for 30 seconds, with a 30-second rest between stretches, 3 d·wk(-1) for 10 weeks. Strength, determined via 1 repetition maximum (1RM) unilateral standing toe raise, and range of motion (ROM) were measured pre-post. In the treatment group, the stretched calf muscle had a significant (p < 0.05) 8% increase in ROM, whereas the nonstretched calf muscle had a significant 1% decrease in ROM. The 1 RM of the stretched calf muscle significantly increased 29%, whereas the 1RM of the nonstretched calf muscle significantly increased 11%. In the control group, neither 1RM nor ROM changed for either leg. The results indicate that 10 weeks of stretching only the right calf will significantly increase the strength of both calves. Hence, chronic stretching can also induce a crosstraining effect for strength but not for the ROM. This study also validates earlier findings suggesting that stretching can elicit strength gains in untrained individuals.

Maximal Respiratory Pressure Reference Values for Hopi Children Ages 4-13.

Anthropometric variables will influence maximal respiratory pressure (MRP) values. Since significant variations exist in pulmonary nomograms amongst different races, it is important that tribe specific tables of normal maximal inspiratory pressures (MIP) and maximal expiratory pressures (MEP) be developed. To date, MRP prediction equations do not exist for Hopi children. PURPOSE: The purpose of this study was to develop MRP reference values and prediction equations for Hopi children in the ages 4-13 years. METHODS: A cross-sectional study was undertaken with 288 healthy children (125 male, 163 female), a 36% representative population of all the Hopi Native children attending Hopi Tribal Elementary Schools in Arizona. MIP and MEP values were measured. RESULTS: Age and the inverse of body mass were consistently significant predictors of the MRPs for both sexes. Predictions using the derived Hopi equations were significantly different (p≤0.001) than those using the equations for Navajo and Caucasian youth across both sexes, making it important for this population to have specific formulae to provide more accurate reference values. CONCLUSIONS: These data were collected from the children of Hopi ancestry resulting in MIP and MEP reference equations which should be used when measuring MIP and MEP in these children ages 4-13 years.

Passive static stretching alters the characteristics of the force-velocity curvature differently for fast and slow muscle groups-A practical application of Hill's equation.

Studies showed fast muscle fibers have a greater constant b value of Hill's equation than that of slow muscle fibers, and the changing ratio of b/Vmax indicates the altered characteristics of muscles under certain conditions such as static stretching. This study was to investigate the effect of acute passive static stretching on the curvature of force-velocity curve in people with different muscle fiber types. A two-step work was conducted in current study through using Hill's equation: 1) calculated b values for each subject at different conditions (non-stretched and stretched) to determine muscle groups, and 2) examined the effect of static stretching on different muscle groups. Sixty-five college students performed isokinetic leg extensions at 5 speeds to test peak torque, following either a non-stretching or two passive static quadriceps stretching exercises. The peak torque and corresponding velocity were used to calculate the b constant. Data reduction consisted of calculating a Z score for each non-stretched and stretched b values. Individuals, whose non-stretched b constant was above or below one standard deviation of the Z score, were designated as the less curved (fast) and more curved (slow) groups, respectively. A paired t-test was used to analyze the pre and post intervention effect on b values for each group (p < 0.05). This study found passive static stretching significantly altered the b constant of the fast group, but no effect on slow group. Therefore, we suggest static stretching should be avoided immediately before fast or explosive activities in individuals using predominantly fast muscle fibers.

Early-phase resistance training strength gains in novice lifters are enhanced by doing static stretching.

This study investigated differences in lower-body strength improvements when using standard progressive resistance training (WT) vs. the same progressive resistance training combined with static stretching exercises (WT + ST). Thirty-two college students (16 women and 16 men) were pair matched according to sex and knee extension 1 repetition maximum (1RM). One person from each pair was randomly assigned to WT and the other to WT + ST. WT did 3 sets of 6 repetitions of knee extension, knee flexion, and leg press 3 days per week for 8 weeks with weekly increases in the weight lifted. The WT + ST group performed the same lifting program as the WT group along with static stretching exercises designed to stretch the hip, thigh, and calf muscle groups. Stretching exercise sessions were done twice a week for 30 minutes during the 8-week period. WT significantly (p < 0.05) improved their knee flexion, knee extension, and leg press 1RM by 12, 14, and 9%, respectively. WT + ST, on the other hand, significantly (p < 0.05) improved their knee flexion, knee extension, and leg press 1RM by 16, 27, and 31, respectively. In addition, the WT + ST group had significantly greater knee extension and leg press gains (p < 0.05) than the WT group. Based on results of this study, it is recommended that to maximize strength gains in the early phase of training, novice lifters should include static stretching exercises to their resistance training programs.

Relationship between isometric and dynamic strength in recreationally trained men.

The purpose of this investigation was to examine the relationships between measures of maximal isometric force (peak force [PF]), rate of force development (RFD), vertical jump performance (VJ) and 1-repetition maximum (1RM) strength in recreationally trained men. The subjects in this study were 26 men ([mean +/- SD]: age 22 +/- 1 years; height 175 +/- 7 cm; mass 90 +/- 10 kg). They were tested for PF using the isometric midthigh pull exercise. The 1RM for the squat and bench press exercise were determined as a measure of dynamic strength. Explosive strength was measured as RFD from the isometric force-time curve. Correlations between the variables were calculated using Pearson product moment correlation coefficient. There was a nearly perfect correlation between measures of PF and 1RM squat (r = 0.97, p < 0.05) and 1RM bench press (r = 0.99, p < 0.05). The correlations were very strong between VJ and PF (r = 0.72, p < 0.05) and 1RM bench press (r = 0.70, p < 0.05). There were also strong correlations between VJ and 1RM squat (r = 0.69, p < 0.05). There were no significant correlations with RFD. The results showed that isometric maximum strength determined during the isometric midthigh pull test correlated well with 1RM and VJ testing. However, RFD measured during the same test did not appear to correlate as well with other measures. The isometric midthigh pull provides an efficient method for assessing strength in recreationally trained individuals. Practitioners wishing to obtain performance data related to maximum strength may wish to consider isometric testing as a less time intensive method of testing.

Muscle Sentry® has No Effect on Total Work Performed and Estimated MVO 2 after High Intensity Short Duration Resistance Training.

Supplements are widely used in recreational and professional participants; however, their claimed benefits are hardly to test. This study compared the total lifted numbers and post-exercise estimated MVO2 while subjects were treated with either Muscle Sentry® (MS) or placebo (PL), in a 7-day washout period. Participants (11 women, 10 men, 20-24 years) performed 3 sets to failure chest and leg press exercises at 8 RM with 2 min rest between sets. Each exercise was performed four times (2 × MS, 2 × PL) at the same time of the day separated by 48 h. The supplementation was ingested 40 min prior to perform the exercise. Prior to the exercise and immediately after each set, both HR and BP were obtained. The rate pressure product (RPP) was then calculated to determine estimated MVO2. Daily RPP and total weight lifted (chest + leg) for each supplementation were averaged. Normalized RPP was the ratio of averaged RPP and averaged total weight lifted. No treatment effect on chest, leg and total lift numbers, normalized post RPP (NPRPP), normalized RPPdiff (NRPPdiff) (p=0.94, 0.86, 0.87, 0.87, 0.43 respectively); No treatment effect on total lift numbers, NPRPP, NRPPdiff for gender (p=0.87, 0.95, 0.96 respectively). Ingestion of Muscle Sentry® 40 min prior to do 3 sets to failure of both chest and leg presses had no effect upon either total lift numbers or estimated MVO2. This suggests that, in some instances, the benefits of Muscle Sentry® are less than those claimed by the manufacturer.

Dim Light Exposure or Melatonin Ingestion Lowers a Type 2 Diabetic's Blood Glucose Removal Rate: A Single Case.

The purpose of this case study is to compare a Type 2 diabetic's postprandial glucoregulatory ability under two different room lighting conditions. The subject was a 56-year-old physically active male with well controlled blood glucose levels (HbA1c ≤ 6% for 5 y) from a combination of diet, exercise, and medication. Two hours post evening meal (380 kcal, 18 g fat, 44 g carbohydrate, 12 g protein), a 45 g carbohydrate challenge was given, and blood glucose was measured every 30 minutes for 2.5 hours under three conditions: dim light (<50 lux) (DL), bright light (>40000 lux) (BL), and bright light plus 6 mg melatonin (BLM). Each condition was repeated 3 times over a period of 6 months with each trial a minimum of seven days apart. The area under the average glucose concentration vs. time plot was different between the three conditions (BL = 909 ± 76; DL = 1078 ± 106; and BLM = 1130 ± 45 mmol·min·l-1). Visual inspection of the average blood glucose vs. time plot suggested that DL and BLM displayed very similar patterns and magnitude, with both DL and BLM having the blood glucose concentrations at each time point that are noticeably greater than BL. Additionally, the average (± standard deviation) blood glucose concentrations for DL (8.8 ± 0.9 mmol·l-1) and BLM (9.1 ± 1.1 mmol·l-1) were respectively 18% and 22% greater than BL (7.5 ± 0.5 mmol·l-1). Melatonin and/or dim light can reduce a Type 2 diabetic's glucoregulatory ability.

Caffeine, acute static stretching and maximum knee flexion strength.

BACKGROUND: Reductions in one-repetition maximum lifts (1RM) following static stretching can be attributed to enhanced neural inhibition, which can be reduced by using stimulants like caffeine. This study compared knee-flexion 1RM following either static stretching (SS) or no-stretching (NS), as well as after ingesting either caffeine (C) or placebo (P). METHODS: Twenty-four participants (12 female, 12 male) performed four random counterbalanced knee flexion 1RM tests. A 1RM test was performed for each condition at the same time of day with ~48 hours separating each test. Static stretching consisted of 5 exercises with the 1RM being performed immediately following the stretching. Caffeine dose was 6 mg/kg body weight, and the placebo was methylcellulose (520 mg). Both doses were administered as pills 60 minutes before the SS or NS procedures. RESULTS: Two-way repeated measures ANOVA showed a significant main effect for NS vs. SS (P<0.001, ηG2=0.23). The main effect for C vs. P, and the interaction between C vs. P and NS vs. SS were not statistically different. Average 1RMs were: CNS = 512±242 N, CSS = 474±241 N, PNS = 498±247 N, and PSS = 460±247 N. CONCLUSIONS: It is concluded that static stretching induced strength decrements are not removed by using stimulants at doses allowed by sport governing organizations.

Static stretching impairs sprint performance in collegiate track and field athletes.

Previous research has shown that static stretching (SS) can diminish the peak force output of stretch-shortening cycle actions while performing a dynamic warm-up (DW) protocol has been shown to enhance performance in similar activities. The purpose of this study was to establish whether the deleterious effects of SS would wash out the performance enhancements obtained from the DW. Eleven males and 11 females, who were athletes of a NCAA Division I track team, performed a DW followed with either a SS or rest (NS) condition. After warm-up was completed, three 40 m sprints were performed to investigate the effects of the SS condition on sprint performance when preceded by DW. Time(s) were obtained from timing gates placed at 0, 20, and 40 m respectively. Testing was conducted over 2 days with a 1 week washout period. Testing order was balanced to eliminate possible order effect. Time for the NS versus the SS group was significantly faster for the second 20 m with a time of 2.41 versus 2.38 seconds (P < or = .05), and for the entire 40 m with a time of 5.6 +/- 0.4 versus 5.7 +/- 0.4 seconds (P < or = .05). The results of this study suggest that performing a SS protocol following a DW will inhibit sprint performance in collegiate athletes.

Chronic static stretching improves exercise performance.

PURPOSE: This study investigated the influence of static stretching exercises on specific exercise performances. METHODS: Thirty-eight volunteers participated in this study. The stretching group (STR) consisted of 8 males and 11 females whose activity was limited to a 10-wk, 40-min, 3-d.wk(-1) static stretching routine designed to stretch all the major muscle groups in the lower extremity. The control group (CON) consisted of 8 males and 11 females who did not participate in any kind of regular exercise routine during the study. Each subject was measured before and after for flexibility, power (20-m sprint, standing long jump, vertical jump), strength (knee flexion and knee extension one-repetition maximum (1RM)), and strength endurance (number of repetitions at 60% of 1RM for both knee flexion and knee extension). RESULTS: STR had significant average improvements (P < 0.05) for flexibility (18.1%), standing long jump (2.3%), vertical jump (6.7%), 20-m sprint (1.3%), knee flexion 1RM (15.3%), knee extension 1RM (32.4%), knee flexion endurance (30.4%) and knee extension endurance (28.5%). The control group showed no improvement. CONCLUSION: This study suggests that chronic static stretching exercises by themselves can improve specific exercise performances. It is possible that persons who are unable to participate in traditional strength training activities may be able to experience gains through stretching, which would allow them to transition into a more traditional exercise regimen.

Early phase strength development: a four-week training comparison of different programs.

The purpose of this study was to explore the effects of various exercise sequences in the early weeks of a strength training program. Forty-two untrained men were randomly assigned to one of 4 training regimens, which were differentiated by the order in which the exercises were performed, and trained 3 days per week for 4 weeks. Three regimens were multiple-set protocols (alternating, blocked, and semiblocked), and the fourth was a single-set protocol. The exercises were arm curls, lateral raises, and triceps extensions. Results showed that the blocked group improved significantly more on the arm curl exercise than the single-set group. No other group comparisons were significant. This finding indicates that a blocked multiple-set regimen is superior to a single-set regimen for certain upper-body exercises in the early stages of strength training.