A 7-d exercise program increases high-molecular weight adiponectin in obese adults.

PURPOSE: High-molecular weight (HMW) adiponectin is the biologically active form of adiponectin and is related to enhanced insulin sensitivity and metabolic function. Previously, we found that 7 d of exercise improves insulin sensitivity in obese subjects; however, whether short-term exercise training affects HMW adiponectin in obese persons is unknown. METHODS: We examined the effect of seven consecutive days of supervised vigorous exercise (60 min · d(-1), 85% HRmax) on HMW adiponectin and leptin secretion in 17 obese individuals (age = 55 ± 3 yr; body mass index = 33.7 ± 0.9 kg · m(-2)). Insulin sensitivity was calculated from an oral glucose tolerance test (ISIOGTT) using the Matsuda Index. Fasting plasma HMW adiponectin and leptin were quantified from blood samples obtained before the ISIOGTT. Glucose and insulin measures were obtained before and every 30 min during the test. Dual-energy x-ray absorptiometry was used to determine body composition, and indirect calorimetry was used to assess fat oxidation. RESULTS: After the intervention, there was a significant increase in HMW adiponectin (3202 ± 543 vs 3878 ± 682 ng · mL(-1), P = 0.02) and a decrease in leptin (36.8 ± 5.1 vs 31.1 ± 4.2 µg · mL(-1), P = 0.03). Further, we observed an increase in ISIOGTT (1.7 ± 0.3 vs 2.1 ± 0.3, P = 0.04) and a decrease in glucose area under the curve (30,871 ± 2105 vs 28,469 ± 1657 mg · dL(-1) for 3 h, P = 0.01). The increase in HMW adiponectin was positively associated with the increase in basal fat oxidation (r = 0.57, P = 0.03), consistent with an improvement in adipose tissue metabolic function. CONCLUSIONS: The data suggest that 7 d of exercise is sufficient not only to improve insulin sensitivity and fat oxidation but also to favorably alter adipokine secretion, independent of changes in body weight or composition.

The effects of high-intensity exercise on skeletal muscle neutrophil myeloperoxidase in untrained and trained rats.

The primary purpose of this study was to examine the effects of high-intensity acute exercise on neutrophil infiltration in different muscle fiber types of untrained rats and to compare postexercise neutrophil accumulation in muscles of untrained and trained animals. The effect of high-intensity acute exercise on blood neutrophil degranulation reaction in trained animals was also elucidated. Neutrophil enzyme myeloperoxidase (MPO) was determined as a measure of neutrophil migration into muscles and blood neutrophil degranulation. Male albino rats were subjected to acute exercise and 5 weeks of training. The used model of intensive acute exercise consisted of 5, 15, and 25 intermittent swimming bouts with the addition of weight (8% of total body mass) for 1-min each, followed by 1.5-min rest intervals. MPO was analyzed in quadriceps muscle (white and red portion) and in soleus muscle 24 h after acute exercise. MPO content in resting blood plasma and neutrophils was determined 48-h following the completion of a training process. In addition, MPO content in the trained rats was measured immediately (in blood plasma and neutrophils) after and 24 h (in muscles) following a single-bout of exercise to exhaustion. The remaining two-third of the trained animals were exposed to a single-bout of nonstop swimming with the addition of 6% body mass until exhaustion. These animals were sacrificed immediately and 24 h after loaded swimming to analyze leukocyte count, MPO content in blood plasma and neutrophils and in muscles, respectively. About 24 h after exercise MPO concentrations in the red portion of quadriceps muscle and in soleus muscle were 4-7-fold higher as compared to the white portion of m. quadriceps. There was an association between the quantity of repetitive bouts of swimming and MPO content in the muscles. The duration of swimming to exhaustion of trained rats was 3.8-fold longer than untrained sedentary control. At rest, plasma MPO concentration was found to be 40% higher in trained rats compared to untrained controls (P < 0.05). Postexercise plasma MPO concentrations were significantly higher both in untrained (+137%; P < 0.05) and trained (+81%; P < 0.05) rats compared to resting values. At rest neutrophil MPO concentration was found to be 33% lower in trained rats compared to untrained controls (P < 0.05). There were no significant differences in muscle MPO concentrations between untrained and trained rats at rest. A single-bout of exercise to exhaustion produced a greater increase in MPO content in untrained compared to trained rats. The data suggest that postexercise neutrophil infiltration is more intensive in red fibers types compared to white fiber types. A smaller neutrophil infiltration in muscles of trained animals after exhaustive exercise suggests a protective effect of previous training to muscle injury.

Using RPE to regulate exercise intensity during a 20-week training program for postmenopausal women: a pilot study.

Feelings of effort sense quantified via the Borg Rating of Perceived Exertion (RPE) scale have been validated for regulating exercise intensity. Most studies validating RPE for exercise prescription have used young, male subjects and only a few exercise sessions. As part of a larger study we examined the accuracy of RPE for regulating exercise intensity in a group of postmenopausal women. Six women (70.0+/-7.1 yr.) were given a maximal graded exercise test. Target RPEs equivalent to 40%, 50% and 60% VO2 max were developed from this test using standard techniques. These RPEs were used to regulate intensity during a 20-wk. training program. During the initial 5 wk. of training target intensity was increased from 40% to 60% VO2 max and exercise duration from 15 to 30 min. Accuracy of exercise intensity regulation was determined by comparing the heart rate during exercise to a target heart rate equivalent to the desired %VO2 max. At Week 2 of training (target 40% VO2 max) the mean intensity produced did not differ from target. During Weeks 4 (target 50% VO2 max), 6 and 10 of training (target 60% VO2 max) the mean exercise intensity was below target. At Week 20 the mean intensity produced was not different from target. This suggests that elderly women can accurately use RPE to regulate exercise intensity, but at intensities above 40% VO2 max an acclimation period is needed.

State-sponsored research on creatine supplements and blood doping in elite Soviet sport.

The former Soviet Union began participating in international sport after World War II and soon achieved a dominant position in the Olympic Games and other competitions. The success of Soviet athletic programs led to charges of unfair practices but, because of secrecy surrounding Soviet research in exercise biochemistry, it has been difficult to substantiate these charges. This article presents previously restricted information regarding the development and use of creatine supplements and blood doping in the USSR. Early work by Olexander Palladin established the role of creatine in muscle function. In the 1970s, Soviet scientists showed that oral creatine supplements improved athletic performance in short, intense activities such as sprints. Subsequent studies in the West substantiated these investigations and have led to the widespread acceptance and use of creatine supplements to enhance muscle function and athletic performance. In addition, however, the Soviet government supported the development of blood doping, which is banned by the International Olympic Committee. Blood doping was pervasive in the USSR in the 1970s and 1980s, and was used by many Soviet athletes in the 1976 and 1980 Olympic Games. Open publication and discussion may help to prevent the abuses that can come from secret scientific research.

Effect of exercise to exhaustion on myeloperoxidase and lysozyme release from blood neutrophils.

Exercise sessions (swimming in rats and treadmill running in humans) resulted in stimulation of neutrophil degranulation in the experiments with animals and in the human study. Myeloperoxidase (MPO) (+67%) and lysozyme (+51%) quantities in the plasma of rats increased significantly immediately after exercise. The blood plasma lysozyme concentration was increased by 41% at the 6th min of treadmill exercise in athletes. The blood concentrations of neutrophil proteins normalized both in humans and animals at rest. The neutrophil protein concentrations in blood increased in parallel with the decrease of their level in leukocytes. The neutrophil capacity for an oxidative burst was not changed by the exercise, but decreased for 3-6 h in the post-exercise period. Such dynamics of the oxidative burst activity suggest a lack of association between this parameter and the degranulation process. The neutrophil proteins that appear in blood during degranulation can be involved in enhancing the bactericidal potency of blood, the activation of granulopoiesis, neutrophil efflux from bone marrow, and the conditioning of blood endothelium for leukocyte extravasation.

Scale construction for measuring adolescent boys' and girls' attitudes, beliefs, perception of control, and intention to engage in leisure-time physical activity.

Using the Theory of Planned Behavior as a framework, the Attitude to Leisure-time Physical Activity, Expectations of Others, Perceived Control, and Intention of Engage in Leisure-time Physical Activity scales were developed for use among high school students. The study population included 20 boys and 68 girls 13 to 17 years of age (for boys, M = 15.1 yr., SD = 1.0; for girls, M = 15.0 yr., SD = 1.1). Generation of items and the establishment of content validity were performed by professionals in exercise physiology, physical education, and clinical psychology. Each scale item was phrased in a Likert-type format. Both unipolar and bipolar scales with seven response choices were developed. Following the pilot testing and subsequent revisions, 32 items were retained in the Attitude to Leisure-time Physical Activity scale, 10 items were retained in the Expectations of Others scale, 3 items were retained in the Perceived Control Scale, and 24 items were retained in the Intention to Engage in Leisure-time Physical Activity scale. Coefficients indicated adequate stability and internal consistency with alpha ranging from .81 to .96. Studies of validities are underway, after which scales would be made available to those interested in intervention techniques for promoting positive attitudes toward physical fitness, perception of control over engaging in leisure-time physical activities, and good intentions to engage in leisure-time physical activities. The present results are encouraging.