A MODEL OF SWIMMING ECONOMY DURING INCREMENTAL EXERCISE

The responses of swimming economy (distance stroke-' (DPS) and stroke rate (SR)) to incremental exercise were examined in 20 highly trained competitive swimmers to derive parameter estimates to model swimming economy during incremental exercise. As the swimmer's velocity increased, DPS was first steady at a maximal value, and then decreased linearly beyond a breakpoint. Conversely, we observed a constant linear increase in SR that did not exhibit a breakpoint or steady state. We defined the maximal DPS as DPS max (m' stroke-'),t he breakpoint as DPSthrehold(m' stroke-'),and the linear decrease as DPSd,, (m' stroke-'velocity-').These results were incorporated into a two segment linear fit of the individual responses. The SR response was described by a regression line and was defined as SR,,, (strokes°minˉ1'~velocityˉ1)

The Effects of Different Passive Static Stretching Intensities on Recovery from Unaccustomed Eccentric Exercise - A Randomized Controlled Trial

Effects of passive static stretching intensity on recovery from unaccustomed eccentric exercise of right knee extensors was investigated in 30 recreationally active males randomly allocated into three groups: high-intensity (70-80% maximum perceived stretch), low-intensity (30-40% maximum perceived stretch), and control. Both stretching groups performed 3 sets of passive static stretching exercises of 60s each for hamstrings, hip flexors, and quadriceps, over 3 consecutive days, post-unaccustomed eccentric exercise. Muscle function (eccentric and isometric peak torque) and blood biomarkers (CK and CRP) were measured before (baseline) and after (24, 48, and 72h) unaccustomed eccentric exercise. Perceived muscle soreness scores were collected immediately (time 0), and after 24, 48, and 72h post-exercise. Statistical time x condition interactions observed only for eccentric peak torque (p=.008). Magnitude-based inference analyses revealed low-intensity stretching had most likely, very likely, or likely beneficial effects on perceived muscle soreness (48-72h and 0-72h) and eccentric peak torque (baseline-24h and baseline-72h), compared with high-intensity stretching. Compared with control, low-intensity stretching had very likely or likely beneficial effects on perceived muscle soreness (0-24h and 0-72h), eccentric peak torque (baseline-48h and baseline-72h), and isometric peak torque (baseline-72h). High-intensity stretching had likely beneficial effects on eccentric peak torque (baseline-48h), but likely harmful effects eccentric peak torque (baseline-24h) and CK (baseline-48h and baseline-72h), compared with control. Therefore, low-intensity stretching is likely to result in small-to-moderate beneficial effects on perceived muscle soreness and recovery of muscle function post-unaccustomed eccentric exercise, but not markers of muscle damage and inflammation, compared with high-intensity or no stretching.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Blunted angiogenesis and hypertrophy are associated with increased fatigue resistance and unchanged aerobic capacity in old overloaded mouse muscle.

We hypothesize that the attenuated hypertrophic response in old mouse muscle is (1) partly due to a reduced capillarization and angiogenesis, which is (2) accompanied by a reduced oxidative capacity and fatigue resistance in old control and overloaded muscles, that (3) can be rescued by the antioxidant resveratrol. To investigate this, the hypertrophic response, capillarization, oxidative capacity, and fatigue resistance of m. plantaris were compared in 9- and 25-month-old non-treated and 25-month-old resveratrol-treated mice. Overload increased the local capillary-to-fiber ratio less in old (15 %) than in adult (59 %) muscle (P < 0.05). Although muscles of old mice had a higher succinate dehydrogenase (SDH) activity (P < 0.05) and a slower fiber type profile (P < 0.05), the isometric fatigue resistance was similar in 9- and 25-month-old mice. In both age groups, the fatigue resistance was increased to the same extent after overload (P < 0.01), without a significant change in SDH activity, but an increased capillary density (P < 0.05). Attenuated angiogenesis during overload may contribute to the attenuated hypertrophic response in old age. Neither was rescued by resveratrol supplementation. Changes in fatigue resistance with overload and aging were dissociated from changes in SDH activity, but paralleled those in capillarization. This suggests that capillarization plays a more important role in fatigue resistance than oxidative capacity

Onset of puberty, menstrual frequency, and body fat in elite rhythmic gymnasts compared with normal controls

Objectives: To assess the prevalence of delayed menarche and abnormal menstrual patterns, as well as the association of menstrual status with physical training in elite rhythmic gymnasts from Greece and Canada. Methods: Fifteen Greek (mean (SEM) age 14.5 (0.2) years) and 30 Canadian (mean (SEM) age 14.7 (0.4) years) rhythmic gymnasts were surveyed for age at menarche, menstrual frequency, and training profile, and measured for height, weight, and percentage body fat (%BF). Seventy eight healthy adolescents served as country specific non-active controls: 38 Greek non-athletes (mean (SEM) age 14.5 (0.1) years) and 40 Canadian non-athletes (mean (SEM) 14.2 (0.1) years). Results: Of the Greek gymnasts, 79% had not yet menstruated compared with 34% of the Canadian gymnasts. Menarche was significantly (p<0.01) delayed in the rhythmic gymnasts (composite mean 13.8 (0.3) years, n = 45) compared with the controls (composite mean 12.5 (0.1) years, n = 78). There was no significant difference between Greek and Canadian gymnasts for the age at menarche (14.2 (0.3) v 13.6 (1.2) years respectively). Menstrual irregularities were reported in 78% (61% oligomenorrhoeic and 17% amenorrhoeic) of the menarcheal athletes. Menarcheal gymnasts were found to be significantly (p<0.05) taller and heavier, with a higher %BF and a lower training frequency and training duration (p<0.05) than the premenarcheal gymnasts. Overall, the mean %BF of the gymnasts was significantly lower (p<0.05) than that of the control subjects. The Canadian controls exhibited a significantly (p<0.05) greater %BF than the Greek controls of the same age. Conclusion: Delayed menarche, menstrual irregularities, and low body fat are common in elite rhythmic gymnasts. Premenarcheal gymnasts train more often and for longer, and have a lower body mass index and less body fat, than menarcheal gymnasts. Prospective studies are needed to explore further these and other factors associated with delayed menarche and menstrual irregularities in female athletes