Search Results

You are looking at 61 - 70 of 435 items for :

Clear All
Restricted access

Shu-Hui Yeh, Hsiu-Ling Lai, Chiu-Yueh Hsiao, Li-Wei Lin, Yu-Kuan Chuang, Yu-Ying Yang and Kuender D. Yang

Background:

Moderate physical activity has been shown to promote immunity. Different moderate physical activities may have different effects on immunity. This study investigated the impacts of a 12-week regular music aerobic exercise (MAE) program on leukocyte distribution, lymphocyte subsets, and lymphocyte polarization.

Methods:

The study used a case-control design with pretest and posttest. Forty-seven middle-age women were recruited for this study. Three participants dropped out, 22 completed the 12-week MAE program, and the other 22 participants who had heat-intolerance or limited schedule eligibility were enrolled as the control group without the MAE exercise.

Results:

Results showed that the MAE exercise for 12 weeks didn’t change red blood cells or total leukocytes but increased lymphocyte counts. The women in MAE group revealed significant increases (P ≤ 0.01) of CD3CD4, CD3CD8, and CD4CD25 cells, associated with Treg polarization showing enhanced FoxP3 but not T-bet, Gata-3, or RORγT expression (P < .01). The control group without exercise revealed insignificant change of lymphocyte subsets or lymphocyte polarization.

Conclusions:

This study shows that MAE increases specific lymphocyte subsets and enhances Treg cell differentiation. It is suggested to encourage moderate physical activity of music aerobic exercise to enhance lymphocyte function of middle-aged women.

Restricted access

E. Randy Eichner

Sickle cell trait can pose a grave risk for some athletes. In the past few years, exertional sickling has killed nine athletes, including five college football players in training. Exercise-physiology research shows how and why sickle red cells can accumulate in the bloodstream during intense exercise bouts. Sickle cells can “logjam” blood vessels and lead to collapse from ischemic rhabdomyolysis. Diverse clinical and metabolic problems from explosive rhabdomyolysis can threaten life. Sickling can begin in 2-3 minutes of any all-out exertion, or during sustained intense exertion – and can reach grave levels very soon thereafter if the athlete struggles on or is urged on by coaches despite warning signs. Heat, dehydration, altitude, and asthma can increase the risk for and worsen sickling. This exertional sickling syndrome, however, is unique and in the field can be distinguished from heat illnesses. Sickling collapse is a medical emergency. Fortunately, screening and precautions can prevent sickling collapse and enable sickle-trait athletes to thrive in their sports.

Restricted access

Elizabeth J. Bradshaw and W.A. Sparrow

The study examined adjustments to gait when positioning the foot within a narrow target area at the end of an approach or “run-up” similar to the take-off board in long jumping. In one task, participants (n = 24) sprinted toward and placed their foot within targets of four different lengths for 8-m and 12-m approach distances while “running through” the target. In a second task, participants (n = 12) sprinted toward and stopped with both feet in the target area. Infra-red timing lights were placed along the approach strip to measure movement times, with a camera positioned to view the whole approach to measure the total number of steps, and a second camera placed to view the final stride, which was analyzed using an in-house digitizing system to calculate the final stride characteristics. In the run-through task, a speed-accuracy trade-off showing a linear relationship (r = 0.976, p < .05) between target length and approach time was found for the 8-m amplitude. An accelerative sub-movement and a later targeting or “homing-in” sub-movement were found in the approach kinematics for both amplitudes. Final stride duration increased, and final stride velocity decreased with a decrease in target length.

Restricted access

Stephanie Van Biervliet, Jean Pierre Van Biervliet, Karel Watteyne, Michel Langlois, Dirk Bernard and Johan Vande Walle

The study aimed to evaluate the effect of exercise on urine sediment in adolescent soccer players. In 25 15-year-old (range 14.4–15.8 yrs) athletes, urinary protein, osmolality and cytology were analyzed by flow cytometry and automated dipstick analysis before (T0), during (T1), and after a match (T2). All athletes had normal urine analysis and blood pressure at rest, tested before the start of the soccer season. Fifty-eight samples were collected (T0: 20, T1: 17, T2: 21). Proteinuria was present in 20 of 38 samples collected after exercise. Proteinuria was associated with increased urinary osmolality (p < .001) and specific gravity (p < .001). Hyaline and granular casts were present in respectively 8 of 38 and 8 of 38 of the urinary samples after exercise. The presence of casts was associated with urine protein concentration, osmolality, and specific gravity. This was also the case for hematuria (25 of 38) and leucocyturia (9 of 38). Squamous epithelial cells were excreted in equal amounts to white and red blood cells. A notable proportion of adolescent athletes developed sediment abnormalities, which were associated with urinary osmolality and specific gravity.

Restricted access

Lucja Pilaczynska-Szczesniak, A. Skarpanska-Steinborn, E. Deskur, P. Basta and M. Horoszkiewicz-Hassan

The aim of the study was to investigate the influence of an increased intake of anthocyanins, contained in chokeberry juice, on the redox parameters in rowers performing a physical exercise during a 1-month training camp. The athletes were randomly assigned to receive 150 mL of chokeberry juice daily, containing 23 mg/100 mL of anthocyanins (supplemented group), or placebo (control group). Before and after the supplementation period, the subjects performed an incremental rowing exercise test. Blood samples were taken from the antecubital vein before each exercise test, 1 min after the test, and following a 24-h recovery period. After the supplementation period, TBARS concentrations in the samples collected 1 min after the exercise test and following a 24-h recovery period were significantly lower in the subjects receiving chokeberry juice than in the control group. In the supplemented group, glutathione peroxidase activity was lower in the samples collected 1 min after the exercise test, and superoxide dismutase activity was lower in the samples taken following a 24-h recovery, as compared to the subjects receiving placebo. These findings indicate that an increased intake of anthocyanins limits the exercise-induced oxidative damage to red blood cells, most probably by enhancing the endogenous antioxidant defense system.

Restricted access

Jeffrey J. Brault, Theodore F. Towse, Jill M. Slade and Ronald A. Meyer

Short-term creatine supplementation is reported to result in a decreased ratio of phosphocreatine (PCr) to total creatine (TCr) in human skeletal muscle at rest. Assuming equilibrium of the creatine kinase reaction, this decrease in PCr:TCr implies increased cytoplasmic ADP and decreased Gibbs free energy of ATP hydrolysis in muscle, which seems contrary to the reported ergogenic benefits of creatine supplementation. This study measured changes in PCr and TCr in vastus lateralis muscle of adult men (N = 6, 21–35 y old) during and 1 day after 5 d of creatine monohydrate supplementation (0.43 g·kg body weight−1·d−1) using noninvasive 31P and 1H magnetic-resonance spectroscopy (MRS). Plasma and red-blood-cell creatine increased by 10-fold and 2-fold, respectively, by the third day of supplementation. MRS-measured skeletal muscle PCr and TCr increased linearly and in parallel throughout the 5 d, and there was no significant difference in the percentage increase in muscle PCr (11.7% ± 2.3% after 5 d) vs. TCr (14.9% ± 4.1%) at any time point. The results indicate that creatine supplementation does not alter the PCr:TCr ratio, and hence the cytoplasmic Gibbs free energy of ATP hydrolysis, in human skeletal muscle at rest.

Restricted access

Timothy D. Mickleborough

Increased muscle oxidative stress and inflammatory responses among athletes have been reported consistently. In addition, it is well known that exhaustive or unaccustomed exercise can lead to muscle fatigue, delayed-onset muscle soreness, and a decrement in performance. Omega-3 polyunsaturated fatty acids (PUFAs) have been shown to decrease the production of inflammatory eicosanoids, cytokines, and reactive oxygen species; have immunomodulatory effects; and attenuate inflammatory diseases. While a number of studies have assessed the efficacy of omega-3 PUFA supplementation on red blood cell deformability, muscle damage, inflammation, and metabolism during exercise, only a few have evaluated the impact of omega-3 PUFA supplementation on exercise performance. It has been suggested that the ingestion of EPA and DHA of approximately 1–2 g/d, at a ratio of EPA to DHA of 2:1, may be beneficial in counteracting exercise-induced inflammation and for the overall athlete health. However, the human data are inconclusive as to whether omega-3 PUFA supplementation at this dosage is effective in attenuating the inflammatory and immunomodulatory response to exercise and improving exercise performance. Thus, attempts should be made to establish an optimal omega-3 fatty-acid dosage to maximize the risk-to-reward ratio of supplementation. It should be noted that high omega-3 PUFA consumption may lead to immunosuppression and prolong bleeding time. Future studies investigating the efficacy of omega-3 PUFA supplementation in exercise-trained individuals should consider using an exercise protocol of sufficient duration and intensity to produce a more robust oxidative and inflammatory response.

Restricted access

Anna Skarpañska-Stejnborn, Lucia Pilaczynska-Szczesniak, Piotr Basta, Ewa Deskur-Smielecka and Magorzata Horoszkiewicz-Hassan

High-intensity physical exercise decreases intracellular antioxidant potential. An enhanced antioxidant defense system is desirable in people subjected to exhaustive exercise. The aim of this study was to investigate the influence of supplementation with artichoke-leaf extract on parameters describing balance between oxidants and antioxidants in competitive rowers. This double-blinded study was carried out in 22 members of the Polish rowing team who were randomly assigned to a supplemented group (n = 12), receiving 1 gelatin capsule containing 400 mg of artichoke-leaf extract 3 times a day for 5 wk, or a placebo group (n = 10). At the beginning and end of the study participants performed a 2,000-m maximal test on a rowing ergometer. Before each exercise test, 1 min after the test completion, and after a 24-hr restitution period blood samples were taken from antecubital vein. The following redox parameters were assessed in red blood cells: superoxide dismutase activity, glutathione peroxidase activity, glutathione reductase activity, reduced glutathione levels, and thiobarbituric-acid-reactive-substances concentrations. Creatine kinase activity and total antioxidant capacity (TAC) were measured in plasma samples, lactate levels were determined in capillary blood samples, and serum lipid profiles were assessed. During restitution, plasma TAC was significantly higher (p < .05) in the supplemented group than in the placebo group. Serum total cholesterol levels at the end of the study were significantly (p < .05) lower in the supplemented group than in the placebo group. In conclusion, consuming artichoke-leaf extract, a natural vegetable preparation of high antioxidant potential, resulted in higher plasma TAC than placebo but did not limit oxidative damage to erythrocytes in competitive rowers subjected to strenuous training.

Restricted access

Torben Pottgiesser, Laura A. Garvican, David T. Martin, Jesse M. Featonby, Christopher J. Gore and Yorck O. Schumacher

Hemoglobin mass (tHb) is considered to be a main factor for sea-level performance after “live high–train low” (LHTL) altitude training, but little research has focused on the persistence of tHb following cessation of altitude exposure. The aim of the case study was to investigate short-term effects of various hematological measures including tHb upon completion of a simulated altitude camp. Five female cyclists spent 26 nights at simulated altitude (LHTL, 16.6 ± 0.4 h/d, 3000 m in an altitude house) where tHb was measured at baseline, at cessation of the camp, and 9 d thereafter. Venous blood measures (hemoglobin concentration, hematocrit, %reticulocytes, serum erythropoietin, ferritin, lactate dehydrogenase, and haptoglobin) were determined at baseline; on day 21 during LHTL; and at days 2, 5, and 9 after LHTL. Hemoglobin mass increased by 5.5% (90% confidence limits [CL] 2.5 to 8.5%, very likely) after the LHTL training camp. At day 9 after simulated LHTL, tHb decreased by 3.0% (90%CL −5.1 to −1.0%, likely). There was a substantial decrease in serum EPO (−34%, 90%CL −50 to −12%) at 2 d after return to sea level and a rise in ferritin (23%, 90%CL 3 to 46%) coupled with a decrease in %reticulocytes (−23%, 90%CL −34 to −9%) between day 5 and 9 after LHTL. Our findings show that following a hypoxic intervention with a beneficial tHb outcome, there may be a high probability of a rapid tHb decrease upon return to normoxic conditions. This highlights a rapid component in red-cell control and may have implications for the appropriate timing of altitude training in relation to competition.

Restricted access

John L. Ivy, Lynne Kammer, Zhenping Ding, Bei Wang, Jeffrey R. Bernard, Yi-Hung Liao and Jungyun Hwang

Context:

Not all athletic competitions lend themselves to supplementation during the actual event, underscoring the importance of preexercise supplementation to extend endurance and improve exercise performance. Energy drinks are composed of ingredients that have been found to increase endurance and improve physical performance.

Purpose:

The purpose of the study was to investigate the effects of a commercially available energy drink, ingested before exercise, on endurance performance.

Methods:

The study was a double-blind, randomized, crossover design. After a 12-hr fast, 6 male and 6 female trained cyclists (mean age 27.3 ± 1.7 yr, mass 68.9 ± 3.2 kg, and VO2 54.9 ± 2.3 ml · kg–1 · min–1) consumed 500 ml of either flavored placebo or Red Bull Energy Drink (ED; 2.0 g taurine, 1.2 g glucuronolactone, 160 mg caffeine, 54 g carbohydrate, 40 mg niacin, 10 mg pantothenic acid, 10 mg vitamin B6, and 10 μg vitamin B12) 40 min before a simulated cycling time trial. Performance was measured as time to complete a standardized amount of work equal to 1 hr of cycling at 70% Wmax.

Results:

Performance improved with ED compared with placebo (3,690 ± 64 s vs. 3,874 ± 93 s, p < .01), but there was no difference in rating of perceived exertion between treatments. β-Endorphin levels increased during exercise, with the increase for ED approaching significance over placebo (p = .10). Substrate utilization, as measured by open-circuit spirometry, did not differ between treatments.

Conclusion:

These results demonstrate that consuming a commercially available ED before exercise can improve endurance performance and that this improvement might be in part the result of increased effort without a concomitant increase in perceived exertion.