Exercise training enhances leg vasodilatory capacity of 65-yr-old men and women

To determine whether extremity vasodilatory capacity may be augmented in older persons by endurance exercise training, lower leg blood flow and conductance were characterized plethysmographically at rest and during maximal hyperemia in 9 men and 10 women aged 64 +/- 3 (SD) yr before and after 31 +/- 6 wk of walking and jogging at 70-90% of maximal oxygen uptake for 45 min 3-5 days/wk. Maximal oxygen uptake expressed as milliliters per kilogram per minute improved 25% in men and 21% in women (P less than 0.01). Maximal leg blood flow and conductance increased in all nine men by an average of 39 +/- 33 (P less than 0.001) and 42 +/- 44% (P less than 0.004), respectively. Results were more variable in women and achieved unequivocal statistical significance only for maximal blood flow (+33 +/- 54% for blood flow and +29 +/- 55% for conductance; P less than 0.02 and P = 0.05, respectively). Body weight and skinfold adiposity declined in both sexes (P less than 0.05). Enhancement of vasodilatory capacity was related to weight loss in men and adipose tissue loss in women (r = 0.61 and 0.51, respectively; P less than 0.05). There were no significant changes in exercise capacity, body weight, or maximal blood flow in four male and three female controls aged 66 +/- 4 yr. Thus adaptability of the lower limb circulation to endurance exercise training is retained to at least age 65 yr.     

Hormonal reactions during heavy training stress and following tapering in highly trained male rowers.

The purpose of this study was to determine whether fasting plasma leptin, cortisol, testosterone and growth hormone concentrations were altered with a heavy increase in training stress followed by a reduced stress in highly trained male rowers. Twelve male national standard rowers (age 20.5 +/- 3.0 years, height 187.9 +/- 6.1 cm, body mass 87.1 +/- 8.3 kg, percent body fat 10.4 +/- 3.2 %) underwent a three-week period of maximally increased training stress followed by a two-week tapering period. The fasting blood samples were obtained every week after the rest day. In addition, the maximal 2000-meter rowing ergometer performance time was assessed before and immediately after the exhaustive training period as well as after the tapering period. A 22 % increase in training stress caused a significant decrease (by 8 %) and increase (by 9 %) in leptin and testosterone, respectively. A further increase in training volume by 25 % significantly reduced leptin further by 35 %. At the same time, no changes were observed in testosterone. Growth hormone was significantly elevated only after the first week of heavy training stress compared to the pretraining level. In the first tapering week, where the physical stress was reduced by 50 %, leptin only significantly increased by 29 %. Testosterone and growth hormone were significantly reduced to almost pretraining levels by the end of the second tapering week. Leptin was further significantly increased during the second tapering week. Cortisol remained relatively constant during the whole study period. Similarly, rowing performance was not significantly changed. We conclude that leptin is more sensitive to the rapid and pronounced changes in training stress compared to measured stress hormones in athletes. In addition, fasting plasma leptin could be regarded as a key signal for metabolic adaptation to exhaustive training stress in highly trained male rowers.     

Rat sex differences in anesthesia

Studies involving substantially lengthy rat surgeries require extended anesthesia periods and often involve use of sodium pentobarbital (PENT). Results of previous experiments from our laboratory and elsewhere suggest that the duration of anesthesia and the need for anesthetic supplementation may differ between male and female rats. In the study reported here, we induced anesthesia in male and female Sprague Dawley rats (n = 10 for each sex), using a three-step procedure: brief induction with 5% isoflurane inhalation, PENT (50 mg/kg of body weight, i.p.), combined with 50 mg of PENT/kg given intragastrically. Adequate anesthesia depth was confirmed by absence of a response to a toe pinch. Plasma PENT concentration was measured at sequential 20-min periods and was found, on average, to be lower (P = 0.03) in male (13.28 +/- 1.13 microg/ml) than in female (20.27 +/- 0.66 microg/ml) rats, and decreased more rapidly (P = 0.003) in male rats. Distribution to a fractionally greater lean body mass and more rapid metabolism in males may account for these differences and explain the need for anesthetic supplementation in male, but not female rats.     

Self-reported training methods of mixed martial artists at a regional reality fighting event

This study surveyed 28 athletes competing at a regional mixed martial arts (MMA) event. The survey attempted to gather information regarding overall training volume, supplement use, and specific exercises used. The survey return rate was 100% (28/28). Twenty-five out of the 28 athletes supplemented their training with strength training. Overall frequency of strength training sessions/week ranged from 1-7, and overall frequency of fighting specific training sessions/week ranged from 3-12. Five out of the 28 athletes used/had used anabolic-androgenic steroids. Twelve of the MMA athletes did not perform exercises specifically for the neck musculature, and only 8 used the power clean and/or power snatch within their strength-training program. The results suggest that strength and conditioning specialists should educate MMA athletes regarding the importance of balanced training, effective exercises, and the side effects of anabolic androgenic steroid use.     

Immunoreactive LHRH in chronic starved rats

The effects of chronic starvation (1/4 of ad libitum food intake) for 21 or 30 days were studied on the hypothalamic and serum concentrations of LHRH, the pituitary and serum concentrations of LH, and the weights of the anterior pituitary, ovary and uterus in adult female Wistar rats (chronic starved group, CSG). Control female rats were fed ad lib. for the same periods (control group, CG). On day 22 or 31, half of the rats of each group were weighed and sacrificed by decapitation. Since there were no difference on above parameters between the experiments on 22nd and 31st day, the results were combined for each parameters. At the time of sacrifice, the body weight of CSG was on the average 44% lower than that of CG rats, and also marked reduction in anterior pituitary (44%), ovarian (61%) and uterine weights (69%) was observed. Serum LH concentrations (mean +/- SE; 5.67 +/- 0.67 versus 33.30 +/- 6.00 ng/ml, P less than 0.001) and pituitary LH content (286.7 +/- 19.4 vs 451.0 +/- 32.8 micrograms, P less than 0.001) were significantly decreased in CSG than in CG rats. However, pituitary LH concentration was not reduced because of the proportional reduction to the pituitary weight of CSG rats. Hypothalamic immunoreactive LHRH (IR-LHRH) content in CSG showed a significant increase as compared to CG rats (5.77 +/- 0.52 vs 4.41 +/- 0.27 ng/hypothalamic extract, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Central and noncentral blood volumes in cirrhosis: relationship to anthropometrics and gender

The size of the central and arterial blood volume (CBV) is essential in the understanding of fluid retention in cirrhosis. Previously, it has been reported decreased, normal, or increased, but no reports have analyzed CBV with respect to gender and lean body mass. The aim of the present study was by means of an optimized technique to reassess it in a large group of patients with cirrhosis compared with healthy controls and matched controls in relationship to their body dimensions and gender. Eighty-three patients with cirrhosis (male/female, 60:23), 67 patients without liver disease (male/female, 22:45), and 14 young healthy controls (male/female, 6:8) underwent a hemodynamic investigation with determination of cardiac output, central circulation time, and CBV determined according to kinetic principles. Related to gender, CBV was lower in male cirrhotics (1.48 +/- 0.30 liter) than in matched and young controls (1.68 +/- 0.33 and 1.72 +/- 0.33 liter, respectively; P < 0.05-0.01). No significant differences in CBV were seen between female cirrhotics and controls. Absolute and adjusted CBVs were lower in the females than in men with cirrhosis (P < 0.001), and men with cirrhosis had lower absolute and body weight-adjusted CBVs than matched controls (P < 0.01). Normalized values of CBV (%total blood volume) were significantly lower in patients with cirrhosis (25 +/- 4%) than in matched controls (31 +/- 7%) and young controls (28 +/- 4%; P < 0.02). CBV correlated significantly with anthropometrics, including lean body mass (r = 0.68-0.82; P < 0.0001). In conclusion, the CBV of patients with cirrhosis was lower than that of controls when adjusted for body dimensions and gender. There are significant gender differences, and signs of underfilling are more pronounced in male than in female patients. The results emphasize the importance of adjustments of blood volumes for anthropometrics and gender.     

Urinary myoglobin quantification by high-performance liquid chromatography: An alternative measurement for exercise-induced muscle damage

This study investigated a means of quantifying urinary myoglobin using a novel reverse-phase high-performance liquid chromatography (RP–HPLC) method that is an alternative measure of exercise-induced muscle damage. It also investigated the effect of storage and alkalization on urinary myoglobin stability issues. An RP–HPLC method was validated by precision and repeatability experiments. Myoglobin stability was determined through spiked urine samples stored at various temperatures over an 8-week period using alkalization and dilution in a pH 7.0 buffer. The method was validated with urine collected from mixed martial arts fighters during a competition and training session. The method produced linearity from 5 to 1000 μg/ml (R² = 0.997), intra- and inter-assay coefficients of variation from 0.32 to 2.94%, and a lower detection limit of 0.2 μg/ml in the final dilution and 2 μg/ml in the original urine sample. Recovery ranged from 96.4 to 102.5%, myoglobin remained stable at 4 °C when diluted in a pH 7.0 buffer after 20 h, and a significant increase (P < 0.01) and an identifiable peak were observed following a mixed martial arts contest and training session. Storage length and conditions had significant effects (P < 0.05) on stability. The method's simplicity and noninvasive nature means it can be used as an alternative muscle damage assay following exercise and trauma.     

Combined aerobic and resistance training and vascular function: effect of aerobic exercise before and after resistance training.

Aerobic exercise training combined with resistance training (RT) might prevent the deterioration of vascular function. However, how aerobic exercise performed before or after a bout of RT affects vascular function is unknown. The present study investigates the effect of aerobic exercise before and after RT on vascular function. Thirty-three young, healthy subjects were randomly assigned to groups that ran before RT (BRT: 4 male, 7 female), ran after RT (ART: 4 male, 7 female), or remained sedentary (SED: 3 male, 8 female). The BRT and ART groups performed RT at 80% of one repetition maximum and ran at 60% of the targeted heart rate twice each week for 8 wk. Both brachial-ankle pulse wave velocity (baPWV) and flow-mediated dilation (FMD) after combined training in the BRT group did not change from baseline. In contrast, baPWV after combined training in the ART group reduced from baseline (from 1,025 +/- 43 to 910 +/- 33 cm/s, P < 0.01). Moreover, brachial artery FMD after combined training in the ART group increased from baseline (from 7.3 +/- 0.8 to 9.6 +/- 0.8%, P < 0.01). Brachial artery diameter, mean blood velocity, and blood flow in the BRT and ART groups after combined training increased from baseline (P < 0.05, P < 0.01, and P < 0.001, respectively). These values returned to the baseline during the detraining period. These values did not change in the SED group. These results suggest that although vascular function is not improved by aerobic exercise before RT, performing aerobic exercise thereafter can prevent the deteriorating of vascular function.     

Onset of puberty in CD-1 mouse pups exposed prenatally through weaning to endophyte-infected tall fescue seed

This study was undertaken to investigate the effects of feeding endophyte - infected (Acremonium coenophialum ) tall fescue seed to CD-1 mouse dams (P(1)) during gestation and lactation, and on the subsequent growth and sexual maturity (onset of puberty) of their male and female offspring (F(1)). Forty-eight 21 d old pups (24 male and 24 female F(1) mice) were weaned from dams fed one of two diets containing 50% rodent chow (w/w) and 50% KY-31 tall fescue (Festuca arundinacea ) seed. The seed in Diet 1 was noninfected, while the seed in Diet 2 was 80% endophyte-infected. At weaning (21 d), the F(1) pups were fed rodent chow, ad libitum throughout the remaining experimental period. At 24 d, they were paired with sexually mature non-treated virgin CD-1 mice (fed 100% rodent chow) for one parturition cycle. Male F(1) mice were sacrificed at 84 d to determine testicular development. The age at the birth of the first litter for Diet 2 F(1) male (76.8 +/- 2.2 d) and female (58.4 +/- 2.1 d) was significantly greater (P<0.05) than the age at parturition for Diet 1 male and female F(1) test mice (64.1 +/- 1.8 and 51.9 +/- 1.2 d, respectively). At parturition, the female F(1) mice showed no significant differences (P>0.05) in either mean parturition weight or number of F(2) pups born per litter. However, total F(2) litter wight (11.38 +/- 1.14 g) and mean weight per F(2) pup (1.40 +/- 0.04 g) for Diet 2 female F(1) mice litters were lower (P<0.05) when compared with Diet 1 females (14.53 +/- 0.57 g and 1.66 +/- 0.02 g, respectively). No significant differences were observed between the two male F(1) treatment groups, for total F(2) litter weight or the number of pups born per F(2) litter. Although Diet 2 F(1) males weighed significantly less (P<0.05) at weaning and at pairing, final body weights at sacrifice (84 d) were not different (P>0.05) from the Diet 1 males.     

Decreased intestinal polyp multiplicity is related to exercise mode and gender in ApcMin/+ mice.

Moderate-intensity treadmill running can alter male Apc(Min/+) mouse polyp formation. This purpose of this study was to examine whether exercise mode differentially affects Apc(Min/+) mouse intestinal polyp development in male and female mice. Male and female Apc(Min/+) mice were randomly assigned to control, treadmill (18 m/min; 60 min/day; 6 days/wk), or voluntary wheel running (24-h access) groups. Nine weeks of training decreased total intestinal polyps by 29% in male treadmill runners (66 +/- 9; P = 0.038) compared with male controls (93 +/- 7). The number of large polyps (>/=1-mm diameter) were also reduced by 38% in male treadmill runners (49 +/- 6; P = 0.005) compared with male controls (79 +/- 6). Treadmill running in female Apc(Min/+) mice and wheel running in both genders did not affect polyp number or size. Spleen weight decreased in male treadmill runners (91 +/- 9 mg; P = 0.011) and wheel runners (75 +/- 6 mg; P = 0.004) compared with controls (141 +/- 13 mg). Plasma IL-6 was reduced by 96% in male treadmill runners (1.2 +/- 0.6 pg/ml) and 78% in male wheel runners (6.6 +/- 3.3 pg/ml) compared with control mice (27.9 +/- 2.8 pg/ml; P < 0.05). Female mice responded similarly with an 86% decrease in plasma IL-6 with treadmill running (3.2 +/- 1.2 pg/ml) and 90% decrease with wheel running (2.9 +/- 2.0 pg/ml) compared with control mice (21.1 +/- 5.3 pg/ml; P < 0.05). The crypt depth-to-villus height ratio in the intestine, an indirect marker of intestinal inflammation, decreased by 21 (P = 0.024) and 24% (P = 0.029), respectively, in male and female treadmill runners but not wheel runners. Physical activity-induced attenuation of intestinal polyp number and size is dependent on exercise mode and differs between genders. The modulation of systemic and intestinal inflammation may also depend on exercise mode.     

Contest competition and men's facial hair: beards may not provide advantages in combat

In contemporary human societies, where direct male-male competition is reduced compared to ancestral societies, sporting competitions remain an avenue for status acquisition via intra-sexual competition. Beards are the most visually salient and sexually dimorphic of men's secondary sexual traits and play a strong role in communicating masculinity, dominance and aggressiveness intra-sexually. Hypotheses have been advanced that beards provide advantages in intra-sexual combat, as protective organs and honest signals of fighting ability. Here we provide the first test of these hypotheses using data from professional mixed martial arts fighters competing in the Ultimate Fighting Championship. We explored whether secondary sexual traits (height, weight, beardedness), fighting stance (southpaw, orthodox), arm reach and past contest experiences impact on contest outcomes. If beards function as protective organs, bearded fighters should succumb to fewer knock-outs, and hence protection to injuries to the jaw, fewer abrasions and lacerations to the face and brain damage than clean-shaven fighters. Alternatively, if beards signal fighting ability then bearded fighters should win more fights. We found no evidence that beardedness was associated with fewer losses by knock-out or greater fighter ability. While fighters with longer reaches won more fights, neither stance nor past experience influenced fight outcomes. We suggest that beards represent dishonest signals of formidability that may serve to curtail the escalation of intra-sexual conflict through intimidation rather than providing advantages in direct combat.     

Measurement of blood volume in the Indian mud eel Amphipnous cuchia (Ham.) (amphipnoidae; pisces).

The blood volume of 10 male and 8 female Amphipnous cuchia (Ham.) were measured through dilution technique method using Evans blue and sodium citrate as anticoagulant. This method was established against heparin. The mean total blood volume and the blood volume per 100 g of body weight for all the weight groups in male were 9.73 +/- 2.45 and 3.10 +/- 0.66, and in female were 10.34 +/- 2.78 and 3.13 +/- 0.66 respectively. The total blood volume of male and female fishes increase as an exponential function of its total body weight.     

Positive correlation between the body weight of anestrous goats and their response to the male effect with sexually active bucks

In the present study, we analyzed the results of two years of response to the male effect in seasonally anestrous goats to investigate whether the activation of female reproductive activity by the male effect is related to the body weight of the females. Seventy-nine adult female Mexican mixed breed goats were used. The anestrous females were exposed during 15 days to sexually active males, and were classified into three categories according to their mean body weight +/-SD (42 +/- 9 kg) (Light: < or = 33 kg, n = 19; Medium: 34-50 kg, n = 46; Heavy: > or = 51 kg, n = 14). More than 98% of the goats from the Medium and Heavy groups showed at least one estrus behavior within the first 15 days following the introduction of the bucks, versus only 63% of the females from the Light group (P < 0.01). The interval between the introduction of the males and the onset of estrus behavior was longer in the females of the Light and Medium groups (4.2 +/- 0.8 and 3.3 +/- 0.3 days) than in the females of the Heavy group (2.0 +/- 0.2 days; P < 0.03). Also, body weight was negatively correlated with latency to first estrus (Spearman r = -0.57; P < 0.001). These results are in agreement with the hypothesis that the ability of anestrous goats to respond to the male effect is positively influenced by their body weight.     

Aerobic fitness and body fat of young British males entering the army.

Aerobic fitness and percent body fat were measured in a sample of 438 male Army recruits between the ages of 17 and 30 prior to the commencement of training. The sample came from all areas of England and Wales. Aerobic fitness, as represented by maximal oxygen uptake (VO2 max), was predicted from the Astrand submaximal bicycle heart rate test. Body fat was predicted from four skinfold measurements. Total group means +/- SD were: age, 19.5 +/- 2.5 years; VO2 max 41.7 +/- 8.3 ml/kg . min; and body fat, 14.5 +/- 4.8% of body weight. VO2 max varied with age, athletic participation and aptitude score. No relationship was found with occupation of parent, prior civilian occupation or smoking severity. When adjusted for methodological differences, VO2 max was slightly below similar Army entrants in Norway and the United States.     

Retrospective injury epidemiology of one hundred one competitive Oceania power lifters: the effects of age, body mass, competitive standard, and gender

The injury epidemiology of competitive power lifters was investigated to provide a basis for injury prevention initiatives in power lifting. Self-reported retrospective injury data for 1 year and selected biographical and training information were obtained via a 4-page injury survey from 82 men and 19 women of varying ages (Open and Masters), body masses (lightweight and heavyweight), and competitive standards (national and international). Injury was defined as any physical damage to the body that caused the lifter to miss or modify one or more training sessions or miss a competition. A total of 118 injuries, which equated to 1.2 +/- 1.1 injuries per lifter per year and 4.4 +/- 4.8 injuries per 1,000 hours of training, were reported. The most commonly injured body regions were the shoulder (36%), lower back (24%), elbow (11%), and knee (9%). More injuries appeared to be of a sudden (acute) (59%) rather than gradual (chronic) nature (41%). National competitors had a significantly greater rate of injury (5.8 +/- 4.9 per 1,000 hours) than international competitors (3.6 +/- 3.6 per 1,000 hours). The relative proportion of injuries at some body regions varied significantly as a function of competitive standard and gender. No significant differences in injury profile were seen between Open and Masters or between lightweight and heavyweight lifters. Power lifting appears to have a moderately low risk of injury, regardless of the lifter's age, body mass, competitive standard, or gender, compared with other sports. Future research should utilize a prospective cohort or case-controlled design to examine the effect of a range of other intrinsic and extrinsic factors on injury epidemiology and to assess the effects of various intervention strategies.     

Growth curves of body weight changes in laboratory-bred female African green monkeys (Cercopithecus aethiops)

Nonlinear growth models having three or four parameter family were applied to individual weight data of female African green monkeys for estimating their growth pattern. The body weight was measured continuously from birth to six years of age with five female laboratory-bred monkeys. A total of 95 weight data were collected from each monkey. The average body weight was 330 g with the standard deviation of +/- 15 g at birth, and 2.71 +/- 0.33 kg at four years of age. The body weight of female African green monkeys was judged to reach a plateau after about four years of age. Five growth models (Gompertz, Logistic, Richards, Bertalanffy, Brody) were applied to these weight to age data. The most suitable coefficient of determination between growth data and growth model was obtained by the application of Gompertz equation. Three parameters of Gompertz equation, mature size (A), rate of maturing (K) and inflexion point (e-1 A) were analyzed in relation to age of menarche. Strong correlations between age of menarche and maturing rate, as well as between age of menarche and inflexion point were observed.     

Abdominal fat distribution and peripheral and hepatic insulin resistance in type 2 diabetes mellitus

We examined the relationship between peripheral/hepatic insulin sensitivity and abdominal superficial/deep subcutaneous fat (SSF/DSF) and intra-abdominal visceral fat (VF) in patients with type 2 diabetes mellitus (T2DM). Sixty-two T2DM patients (36 males and 26 females, age = 55 +/- 3 yr, body mass index = 30 +/- 1 kg/m2) underwent a two-step euglycemic insulin clamp (40 and 160 mU. m(-2). min(-1)) with [3-3H]glucose. SSF, DSF, and VF areas were quantitated with magnetic resonance imaging at the L(4-5) level. Basal endogenous glucose production (EGP), hepatic insulin resistance index (basal EGP x FPI), and total glucose disposal (TGD) during the first and second insulin clamp steps were similar in male and female subjects. VF (159 +/- 9 vs. 143 +/- 9 cm2) and DSF (199 +/- 14 vs. 200 +/- 15 cm(2)) were not different in male and female subjects. SSF (104 +/- 8 vs. 223 +/- 15 cm2) was greater (P < 0.0001) in female vs. male subjects despite similar body mass index (31 +/- 1 vs. 30 +/- 1 kg/m2) and total body fat mass (31 +/- 2 vs. 33 +/- 2 kg). In male T2DM, TGD during the first insulin clamp step (1st TGD) correlated inversely with VF (r = -0.45, P < 0.01), DSF (r = -0.46, P < 0.01), and SSF (r = -0.39, P < 0.05). In males, VF (r = 0.37, P < 0.05), DSF (r = 0.49, P < 0.01), and SSF (r = 0.33, P < 0.05) were correlated positively with hepatic insulin resistance. In females, the first TGD (r = -0.45, P < 0.05) and hepatic insulin resistance (r = 0.49, P < 0.05) correlated with VF but not with DSF, SSF, or total subcutaneous fat area. We conclude that visceral adiposity is associated with both peripheral and hepatic insulin resistance, independent of gender, in T2DM. In male but not female T2DM, deep subcutaneous adipose tissue also is associated with peripheral and hepatic insulin resistance.     

山东省儿童青少年生长发育20年变化趋势

为了解近20年来山东省儿童青少年生长发育的变化趋势, 本文利用山东省1985年、1995年和2005年学生体质调研资料, 分析了7—18岁儿童青少年生长的长期变化。20年间, 7—18岁身高平均增长6.27cm(城男)、5.02cm(城女)、7.62cm(乡男)、5.69cm(乡女); 体重平均增长9.97kg(城男)、6.02kg(城女)、7.96kg(乡男)、4.87kg(乡女)。BMI明显增长, 7—18岁平均增长2.57kg/m2(城男)、1.46kg/m2(城女)、1.71kg/m2(乡男)、0.93kg/m2(乡女)。发育水平上的城乡差别依然存在, 但身高的城乡差别逐步缩小, 体重的城乡差别明显扩大。下肢长指数(身高—坐高)的增长幅度大于坐高的增长幅度。总之,1985—2005年的20年间,山东省7—18岁儿童青少年在身高、体重、BMI和身材比例等方面都发生了较大变化。     

Lactate and rate of perceived exertion responses of athletes training for and competing in a mixed martial arts event

Lactate and rate of perceived exertion (RPE) was monitored in 6 male subjects training for and competing in a mixed martial arts event held in Butte, Montana, to determine 1) the metabolic demands of the sport and 2) the effectiveness of the prebout interval training programs chosen to help prepare the competitors for this event. The training lactate measurements ranged from 8.1 to 19.7 mmol.L, and the training RPE levels ranged from 15 to 19 on Borg's Category Scale of perceived exertion, the scores of which ranged from 6 to 20. The postbout lactate measurements ranged from 10.2 to 20.7 mmol.L, and the post-bout RPE measurements ranged from 13 to 19. Of the 4 subjects that had both training and postbout lactate measurements, 3 had obtained lactate levels during training that exceeded lactate levels immediately after the bout. This indicated that, when using lactate measurements as a benchmark, the conditioning training was effective for these 3 athletes. When we used RPE scores as a benchmark, the conditioning was effective for all 4 subjects because all subjects reached 18-19 during their training, which was at least as high as their reported post-bout RPE levels.     

Intermittent fasting during winter and spring affects body composition and reproduction of a migratory duck

We compared food intake, body mass and body composition of male and female black ducks (Anas rubripes) during winter (January-March). Birds were fed the same complete diet ad libitum on consecutive days each week without fasting (control; nine male; nine female) or with either short fasts (2 day x week(-1); nine male; nine female), or long fasts (4 day x week(-1); eleven male; twelve female). We continued treatments through spring (March-May) to measure the effect of intermittent fasts on body mass and egg production. Daily food intake of fasted birds was up to four times that of unfasted birds. Weekly food intake of males was similar among treatments (364 g x kg(-1) x week(-1)) but fasted females consumed more than unfasted females in January (363 g x kg(-1) x week(-1) vs. 225 g x kg(-1) x week(-1)). Although both sexes lost 10-14% body mass, fasted females lost less mass and lipid than unfasted females during winter. Total body nitrogen was conserved over winter in both sexes even though the heart and spleen lost mass while the reproductive tract and liver gained mass. Intermittent fasting increased liver, intestinal tissue and digesta mass of females but not of males. Fasting delayed egg production in spring but did not affect size, fertility or hatching of the clutch. Females on long fasts were still heavier than controls after laying eggs. Thus black ducks combine flexibility of food intake with plasticity of digestive tract, liver and adipose tissue when food supply is interrupted during winter. Females modulate body mass for survival and defer reproduction when food supply is interrupted in spring.