Effect of specific test procedures on plasma lactate concentration and peak oxygen uptake in endurance athletes

Plasma lactate accumulation during submaximal work and VO2peak were determined on the bicycle ergometer and on the treadmill in all round trained control subjects (n = 9) and in specifically trained athletes such as distance runners (n = 9) and racing cyclists (n = 8). Plasma lactate concentration at equivalent levels of oxygen uptake was lower during treadmill exercise than during bicycle exercise in the controls and in the runners, but the difference between the two work modalities was more pronounced in the runners. In contrast to the runners, the cyclists had a higher plasma lactate concentration on the treadmill. VO2peak values on the two ergometers were similar in the controls, while the specifically trained athletes reached the highest value when they were tested with the exercise test which is specific to the training conducted. In the runners VO2peak was 14% higher on the treadmill than on the bicycle ergometer and in the cyclists VO2peak was 11% higher on the bicycle ergometer. It is concluded that the difference in plasma lactate concentration during submaximal work and in VO2peak between treadmill and bicycle exercise can be affected by the training conditions of the subjects.     

Training effects on blood zinc levels in humans

Effects of physical training on fasting erythrocyte and plasma zinc distributions were studied on seven previously sedentary male students. The training consisted of running over 5 km, 6 times/week for 10 weeks. Maximum aerobic capacity (VO2max) and 12 min walk-run performance increased significantly (p less than 0.01) after training. The erythrocyte concentrations of total zinc and of zinc derived from carbonic anhydrase I (CA-I) rose significantly (p less than 0.05) after training, whereas no such effects were noted in CA-II-derived zinc, Cu2Zn2 superoxide dismutase-derived zinc, and other zinc. On the other hand, no effect of training was found in total or alpha 2-macroglobulin-bound zinc in plasma, although albumin-bound zinc concentration declined significantly (p less than 0.05). Following the training period, however, the response to a VO2max test of the van Beaumont quotient (J Appl Physiol 1973;34:102-6) for total plasma zinc had decreased significantly (p less than 0.05), suggesting a relative reduction of the circulating exchangeable zinc. In addition, there were significant (p less than 0.05) decreases in plasma iron and ferritin concentrations after training, indicating latent iron deficiency anemia. These results may suggest that the changes in CA-I-derived zinc and/or albumin-bound zinc portend zinc deficiency during running training and that sports anemia precedes hypozincemia in athletes.     

Survey of menstrual function in young Nigerian athletes

Menstrual function was assessed comparatively in different categories of 155 Nigerian athletes, aged 13-19 years, and 135 nonathletes, aged 12-18 years, who answered questionnaires and were interviewed. Menstruation was more regular and normal in the nonathletes (44%) than the athletes (21%). Although both groups generally had similar patterns of menstrual dysfunction, secondary amenorrhea or oligomenorrhea (O/A) was more prevalent in the athletes (25%) than the nonathletes (10%). Among the athletes, only the distance runners were significantly lighter and leaner than nonathletes and athletes of other sports (P less than 0.05). Regardless of sports activity, oligomenorrheic subjects had substantially lower body weight relative to stature and were leaner than subjects of the other menstrual categories. In the oligomenorrheic group, a greater proportion of the athletes (59%) and nonathletes (57%) had lean body mass values below the 41st percentile. The premenarche-trained athletes (48%) reported a higher incidence of menstrual cycle irregularities than the athletes who began training after the menarche. Results support the role of body composition-related factors in the etiology of exercise-associated O/A.     

Do asymptomatic marathon runners have an increased prevalence of meniscal abnormalities? An MR study of the knee in 23 volunteers

Excessive repetitive musculoskeletal loads and stresses associated with intense physical activity may lead to deterioration of the menisci of the knee. Therefore, MR imaging was performed on the knees of 23 asymptomatic marathon runners (eight men, 15 women; average age, 40 years; average number of years training, 10; average training distance per week, 41 miles) to determine the prevalence of meniscal signal abnormalities. None of the runners had previous knee injuries or surgery and each of them regularly competes in 26-mile, 50-mile, or 100-mile marathon races. T1-weighted coronal MR images and proton density-weighted and T2-weighted sagittal images were obtained with a 1.5-T MR system and a transmit/receive extremity coil. The medial and lateral menisci were divided into four portions, or horns, and a total of 92 horns were evaluated (i.e., four horns per knee: medial posterior, medial anterior, lateral posterior, and lateral anterior). Two meniscal horns (2%) had grade 3 signal (grade 3 indicates a meniscal tear), 12 (13%) had grade 2 signal, 29 (32%) had grade 1 signal (grades 1 and 2 are indicative of meniscal degeneration), and 49 (53%) had grade 0 signal (grade 0 is normal). Overall, the prevalence of meniscal tears was 9% (two meniscal tears found in 23 runners). This is lower than the prevalence of MR signal abnormalities indicative of meniscal tears reported for asymptomatic, nonrunner athletes (20% of 20 athletes) and for asymptomatic nonathletes (16% of 74 subjects). Fifty-three percent of the meniscal horns of the nonrunner athletes had grade 1 or 2 signal, indicative of meniscal degeneration. Our results indicate that the prevalence of meniscal tears in marathon runners is no higher than the prevalence reported for sedentary persons, and the runners have the same amount of meniscal degeneration as do nonrunner athletes.     

Diet, hormonal, and metabolic factors affecting bone mineral density in adolescent amenorrheic and eumenorrheic female runners.

Seven adolescent female runners with secondary amenorrhea and six adolescent eumenorrheic female runners received dietary supplements of 1200 mg calcium carbonate and 400 IU vitamin D/d for 12 months. Bone mineral density (BMD) of the axial skeleton was measured by dual photon densitometry at the beginning and end of the 12 month period. Plasma estradiol and ionized calcium concentration were also determined. Bone mineral density decreased in two of the amenorrheic subjects, with the lowest estradiol values concurrent with the severest training regimen and highest calcium intake. There was a significant decrease in plasma estradiol concentration in the amenorrheic runners (p less than 0.05). Plasma ionized calcium and estradiol explained 99% of the variation in BMD (r2 = 0.999). A significant inverse relationship between plasma estradiol and miles run/week was observed (r2 = -0.748). Adolescent female runners who train extensively and have low plasma estradiol levels may be adversely affecting BMD despite supplemental calcium and vitamin D intake.     

Physical activity,hormone replacement therapy and plasma lipoprotein-lipid levels in postmenopausal women

We assessed the cross-sectional associations between hormone replacement therapy (HRT), habitual physical activity levels and plasma lipoprotein-lipid levels in postmenopausal women. Sedentary (n = 19), active nonathlete (n = 20) and endurance-trained (n = 21) postmenopausal women, with half of each group on and half not on HRT, underwent assessments of plasma lipids, VO2max, body composition, diet and common genetic variants. The groups' physical characteristics were generally similar though body weight was higher in the active nonathletes, and body fat was lower and VO2max higher in the athletes. HRT was associated with beneficial total cholesterol, LDL-C and HDL-C levels in sedentary and active nonathlete women. Plasma lipoprotein-lipid profiles were similar in women athletes on and not on HRT, with their profiles being only slightly better than sedentary and physically-active women on HRT. After controlling for HRT status, VO2max was correlated with total cholesterol (r = -0.51, p = 0.0001), LDL-C (r = -0.52, p = 0.0001), HDL-C (r = 0.25, p = 0.055), HDL 2 -C (r = 0.24, p = 0.08) and TG levels (r = -0.46, p = 0.0001). After controlling for HRT status, % body fat was correlated with total cholesterol (r = 0.43, p = 0.001), LDL-C (r = 0.38, p = 0.003), HDL-C (r = -0.29, p = 0.025), HDL 2 -C (r = -0,26, p = 0.07) and TG levels (r = 0.40, p = 0.002). Dietary fat intake was similar among the groups. APO E genotype was only associated with plasma lipid profiles in athletes, as those with at least one APO E2 allele tended to have better lipid profiles than those with only APO E3 or E4 alleles. Thus, HRT, exercise training and body composition are associated with plasma lipid levels in postmenopausal women; common polymorphic variations at key lipid metabolism-related gene loci also may interact with exercise training to affect their plasma lipid profiles.     

Hematological recovery in male ultramarathon runners: the effect of variations in training load and running time

AIM: Haematological response to the 2001 downhill Comrades Marathon was compared in high (>120 km/w in training; 3 weeks of pre-race taper) and low (<80 km/w in training; 2 weeks of pre-race taper) training status groups. METHODS: Full blood counts, differential lymphocyte counts (CD3, CD4, CD8, CD19, CD56), serum cortisol, C-reactive protein (CRP) and creatine kinase (CK) were measured in blood samples donated 21 hours before and 16 hours after a 90 km ultramarathon. RESULTS: Despite significantly faster mean race finishing time (8.03 h vs 10.53 h; p<0.001) and greater percentage incidence (55.6% vs 40%) of post-race upper respiratory tract infection (URTI) in the highly trained group, these faster runners did not show evidence of a slower post-race recovery in terms of total leukocyte, neutrophil, total or differential lymphocyte counts (p>0.05). CRP concentrations were, however, markedly higher in the slower, less trained group (65.3+/-10.7 vs 38.3+/-5.9; p<0.01). CONCLUSIONS: Despite greater systemic evidence of post-race muscle inflammation and an acute phase response in the slower runners in a downhill ultramarathon race, the haematological recovery of well trained runners who undergo a 3-week taper period prior to the ultramarathon is not different to that in less trained runners who spend almost 3 hours longer on the road. The higher prevalence of post-race URTI symptoms in the fast, well trained group does not appear to be related to lymphocyte recovery in peripheral blood.     

Exercise and immune function. Recent developments

Comparison of immune function in athletes and nonathletes reveals that the adaptive immune system is largely unaffected by athletic endeavour. The innate immune system appears to respond differentially to the chronic stress of intensive exercise, with natural killer cell activity tending to be enhanced while neutrophil function is suppressed. However, even when significant changes in the level and functional activity of immune parameters have been observed in athletes, investigators have had little success in linking these to a higher incidence of infection and illness. Many components of the immune system exhibit change after prolonged heavy exertion. During this 'open window' of altered immunity (which may last between 3 and 72 hours, depending on the parameter measured), viruses and bacteria may gain a foothold, increasing the risk of subclinical and clinical infection. However, no serious attempt has been made by investigators to demonstrate that athletes showing the most extreme post-exercise immunosuppression are those that contract an infection during the ensuing 1 to 2 weeks. This link must be established before the 'open window' theory can be wholly accepted. The influence of nutritional supplements, primarily zinc, vitamin C, glutamin and carbohydrate, on the acute immune response to prolonged exercise has been measured in endurance athletes. Vitamin C and glutamine have received much attention, but the data thus far are inconclusive. The most impressive results have been reported in the carbohydrate supplementation studies. Carbohydrate beverage ingestion has been associated with higher plasma glucose levels, an attenuated cortisol and growth hormone response, fewer perturbations in blood immune cell counts, lower granulocyte and monocyte phagocytosis and oxidative burst activity, and a diminished pro- and anti-inflammatory cytokine response. It remains to be shown whether carbohydrate supplementation diminishes the frequency of infections in the recovery period after strenuous exercise. Studies on the influence of moderate exercise training on host protection and immune function have shown that near-daily brisk walking compared with inactivity reduced the number of sickness days by half over a 12- to 15-week period without change in resting immune function. Positive effects on immunosurveillance and host protection that come with moderate exercise training are probably related to a summation effect from acute positive changes that occur during each exercise bout. No convincing data exist that moderate exercise training is linked with improved T helper cell counts in patients with HIV, or enhanced immunity in elderly participants.     

心理应激和心理训练对不同特质焦虑运动员免疫指标的影响

以马腾斯的特质焦虑量表一运动竞赛焦虑量表成人选用ＳＣＡＴ－Ａ问卷为依据,测定心理应激和心理训练对不同特质焦虑运动员外用血淋巴细胞增殖能力和血浆白细胞介素－１活性（ＩＬ－１）的影响。结果表明：高、低焦虑运动员心理应激后淋巴细胞增殖能力显著下降,同时高焦虑运动员表现有血浆ＩＬ－１活性显著升高;心理应激后低焦虑运动员血浆ＩＬ－１活性改变无显著性差异。提示应激后机体免疫力改变和人格特质类型存在着内在的联系。经过心理训练,运动员对心理应激产生适应,淋巴细胞增殖能力和ＩＬ－１活性与心理应激前比较无显著性差异。     

Zinc and copper status in women by physical activity and menstrual status

Zinc and copper status of 33 eumenorrheic and 12 amenorrheic runners and 19 eumenorrheic and 8 amenorrheic nonrunners was studied. Three-day diet records and fasting blood samples were collected and analyzed. No indices of zinc or copper status differed as a function of menstrual status. Although zinc intakes of runners tended to be higher than nonrunners, plasma zinc concentrations tended to be lower. Runners had significantly higher erythrocyte zinc concentrations than nonrunners (12.4 +/- 0.2 vs 11.5 +/- 0.3 micrograms/g; p less than 0.05). Copper intakes of runners also tended to be higher than nonrunners. Mean plasma copper concentration of runners was significantly higher than nonrunners (18.8 +/- 0.5 vs 16.1 +/- 0.6 mumol/L; p less than 0.01) but erythrocyte copper was significantly lower (1.06 +/- 0.02 vs 1.26 +/- 0.03 micrograms/g; p less than 0.01). The observed differences between runners and nonrunners suggest that chronic exercise may induce redistribution of zinc and copper.     

Modification of plasma glycosaminoglycans in long distance runners

BACKGROUND: It is well documented that exercise reduces the risk of thromboembolic disease, possibly by increasing the plasma concentration of anticoagulant-antithrombotic compounds. OBJECTIVES: As plasma glycosaminoglycans (GAGs) play a role in the anticoagulant-antithrombotic potential of plasma, to examine the concentration and profile of these compounds in well trained, long distance runners and sedentary subjects. METHODS: Plasma GAGs were measured in 10 male, long distance runners and 10 sedentary counterparts before and after ergometric tests. GAGs were extracted, purified, and identified by electrophoretic and enzymatic methods, and measured as hexosamine. RESULTS: Plasma GAGs found in sedentary subjects were slow migrating heparan sulphates I and II, keratan sulphate I, and chondroitin 4-6-sulphate. Those found in trained athletes were slow migrating heparan sulphate I, chondroitin 4-6-sulphate (or keratan sulphate I), and fast migrating heparan sulphate. Total plasma concentrations of GAGs were higher in athletes than in sedentary subjects at rest. In sedentary subjects, plasma GAGs did not change after cycle ergometric exercise at 80% of their anaerobic threshold. However, the appearance of a novel band of heparan sulphate migrating faster than fast migrating heparan sulphate was observed in athletes after exercise. CONCLUSIONS: Exercise changes the amount and profile of plasma GAGs; these changes may play a role in protecting subjects who practise aerobic sports against developing cardiovascular disease.     

Musculoskeletal health in elite male adolescent middle-distance runners.

The impact of high training volumes on musculoskeletal adaptations of male adolescents is poorly understood. We compared bone mineral content (BMC) of total body, lumbar spine and proximal femur using Dual X-ray Absorptiometry (Lunar Prodigy, GE Medical Systems, Madison WI) in elite level (n=20), male adolescent middle distance runners (mean 16.8 yrs, range 14-18 yrs) and age-matched (n=20) controls. Athletes averaged 14 hrs of physical activity per week and controls reported participating in physical activity an average of two hrs per week. Total body mass was 10.97 kg less in athletes than controls (p=0.005). Within the total body mass difference, fat tissue mass of athletes was 10.93 kg less in athletes than controls (p= 0.001). Multiple regression analysis identified total body lean mass and total body fat mass as the strongest predictors of total body BMC (R2 0.71). After adjusting for lean tissue mass per kg of body weight (p=0.07), no difference in BMC was detected. Lower limb muscle strength and macronutrient intakes were also measured but no between group differences were found. The number of weeks of training and/or competition missed through injury was not associated with total body BMC (R2=0.19) among athletes. Our results imply high training volumes in middle distance running are not detrimental to musculoskeletal health and are associated with positive body composition profiles in elite adolescent male athletes.     

Neural, metabolic, and performance adaptations to four weeks of high intensity sprint-interval training in trained cyclists

The purpose of this study was to investigate the effects of short-term, high-intensity sprint training on the root mean squared (RMS) and median frequency (MF) derived from surface electromyography (EMG), as well as peak power, mean power, total work, and plasma lactate levels in trained cyclists when performed concurrently with endurance training. Seventeen trained cyclists were randomly assigned to a sprint training (S) group (n = 10, age 25 +/- 2.0 y) or a control (C) group (n = 7, age 25 +/- 0.5 y). Sprint training was performed bi-weekly for four weeks, comprising a total of 28 min over the training period. EMG measurements were taken before and after training during a series of four 30-s sprints separated by four minutes of active recovery. Plasma lactate, peak power, mean power, and total work were measured during each sprint bout. Following sprint training a significant increase occurred in the RMS of the vastus lateralis with a decrease in MF of the same muscle. Values for the vastus medialis did not change. Pre training exercising plasma lactate values were higher (p < 0.05) in C compared to S, but did not change with training. Exercising plasma lactate values increased (p < 0.05) from pre to post training in S, but were not different from C post training. Total work output increased from pre to post in S (p = 0.06). Peak power, mean power, and V.O (2)max increased (p < 0.05) pre to post training in S and C, indicating C was not a true control. In conclusion, these data suggest that four weeks of high-intensity sprint training combined with endurance training in a trained cycling population increased motor unit activation, exercising plasma lactate levels, and total work output with a relatively low volume of sprint exercise compared to endurance training alone.     

Achilles tendinopathy in club runners

Ultrasound (US) changes within the Achilles tendon are present in asymptomatic Achilles individuals. We assessed the association of US signs with symptoms of Achilles tendinopathy in a study group of club level running athletes and in a control group of athletes training at least 2 times per week. The Achilles tendon was assessed in its entirety on longitudinal US scans, at the musculotendinous junction (MTJ), the calcaneal insertion site, and at a midtendon point. 25 middle distance runners, 19 males and 6 females, aged from 18 to 58, were enrolled in each group. When compared to control athletes, club level runners presented significantly increased tendon thickness (p=0.046) at the musculo-tendinous junction, and increased tendon thickness, with no statistical significance, at the other landmarks points. Although club level runners were significantly more symptomatic and predisposed to develop signs of tendinopathy than control athletes (p=<0.001), ultrasound abnormalities were not significantly associated with local symptoms complained at the US investigation time. Prospective studies on asymptomatic athletes are needed to define the predictive value of US signs of Achilles tendinopathy in the development of symptoms in the long-term.     

Neuroendocrine system and mental function in sedentary and endurance-trained elderly males.

Hypothalamic-pituitary-adrenal (HPAA) and -gonadal (HPGA) axis modification and cognitive impairments have been reported in elderly subjects and related to physical training status. The aim of this study was to investigate if HPAA and HPGA regulation are altered in elderly distance runners (RUN; n = 8; age: 68.9+/-4.2 yrs; training: 65+/-20 km/wk over the last 20 yrs; means +/- SD) or are affected in elderly sedentary individuals (SED; n = 11; age: 69.1+/-2.6 yrs) by an aerobic training over 20 weeks (3 times/week, 30-60 min walking), respectively. The protocol included assessment of the hormone profile in basal non-suppressed state as well as evaluation of hormonal responses to dexamethasone (DEX, 1.5 mg) induced adrenal suppression, to post-DEX combined corticotrophin releasing hormone (CRH; 0.7 microg/kg) and luteinizing hormone releasing hormone (LHRH, 0.7 microg/kg) stimulation and to exercise challenge (30 min cycle ergometry at 65% VO2max). Mental functions influenced by HPAA and HPGA activity were also assessed in RUN and SED before (SED-PRE) and after (SED-POST) the training program. Basal and post-DEX plasma concentrations of adrenocorticotropic hormone (ACTH), cortisol (CSL), luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone (T) did not differ between RUN and SED-PRE. Basal plasma free T concentration was significantly lower in RUN (RUN: 10.23+/-2.41 pg x ml(-1) vs. SED-PRE: 16.6+/-5.59 pg x ml(-1)). During releasing hormone challenge test after DEX administration (DEX/RH), no differences were found between RUN and SED-PRE in plasma ACTH, LH, FSH and T response. During this stimulation test, plasma CSL was significantly higher in RUN than in SED-PRE after 90 min (RUN: 5.86+/-3.65 microg x dl(-1) vs. SED-PRE: 2.74+/-2.09 microg x dl(-1)). Differences in plasma CSL concentrations between groups were not induced by 30-min exercise challenge. Basal hormone profile was not altered by training in SED. During DEX/RH only plasma ACTH concentration was significantly higher in SED-POST compared to SED-PRE. Long and short-term memory function did not differ between RUN, SED-PRE and SED-POST. Our data suggest that following post-DEX CRH/LHRH challenge elderly endurance athletes reveal-in the absence of altered peak values-a pattern of prolonged secretion of glucocorticoids. However, the high interindividual variability of plasma ACTH and CSL concentrations shows that reduced corticotropic sensitivity to negative feedback is not always induced by chronic exercise stress. Lower plasma free T concentrations in RUN compared to SED are not caused by modified LH synthesis-secretion capacity.     

The changes in running performance and maximal oxygen uptake after long-term training in elite athletes

AIM: The relationship between VO2max (mL x kg(-1) x min(-1)) and running performance has been assessed in cross-sectional studies. Follow-up studies of the long-term effects of running training on the changes in performance and VO2max have not been undertaken. METHODS: Twenty-five male endurance-trained (MET) and 8 female endurance-trained (FET) athletes were tracked over 4 years. In each event the athletes were divided into Class A, including half the number of athletes with the best performances, and Class B. VO2max, examined at the end of the competitive season, and the best performance was chosen each year. RESULTS: After 3 years of training, in MET and FET athletes the performance improved by 1.77% and 0.69% (P<0.01 and P=0.579), respectively. In Class A runners, training resulted in non-significant increase in performance (-0.04%) (P=0.982) and in Class B runners, performance increased by 3.16% (P=0.001). In all groups VO(2max) remained essentially unchanged. Longitudinal changes in the VO2max were not related with the changes in running performance in any group. CONCLUSIONS: This study show than in older runners with more years of training, heavy training does not produce improvements in running performance neither changes in the VO2max. It is possible that these elite athletes have reached the plateau in their performance; although unlikely, some improvement in training techniques may happen and break the present limit. In younger runners with less years of training, heavy training produce improvements in running performance without changes in the VO2max. These athletes that had not attained his biological limits at the beginning of study improved the performance in competition and it is quite probable that this improvement be due to training. The changes in performance were not related to changes in VO2max. Consequently, another physiological or psychological variables must be studied by longitudinal form to explain the variability of performance in competition.     

Dietary intake, anthropometric measurements, and blood lipid values in weight training athletes (body builders)

Dietary intake, plasma lipid levels, and anthropometric measurements were studied in 76 weight trained athletes (body builders) who had been following a consistent eating and training program for at least 2 years prior to the study. Dietary data were collected using the 7-day diet record. Nutrient analysis indicated that these athletes followed an atherogenic diet, characterized by a high-fat, high-cholesterol intake. The high-cholesterol intake was due to a high egg intake, which varied from 0 to 81 eggs per week. Although those athletes with a high egg intake consumed significantly more fat and cholesterol than those with a low egg intake, plasma total cholesterol levels (mean = 182.9 +/- 25.7) did not differ over the range of egg intakes. Plasma HDL-cholesterol levels were higher and plasma triacylglycerol levels were lower at a high egg intake compared with that at a low egg intake. Plasma uric acid was not affected by the high animal protein intake. Despite the unfavorable intake of macronutrients, food alone supplied adequate amounts of micronutrients as compared with the RDA. Using different measurements of obesity, it was difficult to classify this group of athletes as overweight or obese, due to increased muscle development.     

Can reticulocyte parameters be of use in detecting iron deficient erythropoiesis in female athletes?

BACKGROUND: The purpose of this study was to investigate whether monitoring reticulocyte profiles, which are known to respond to iron store depletion in sedentary populations, could also be utilised with intensely training athletes. METHODS: A retrospective study of blood samples from 134 national level athletes (61 males, 73 females) at the Australian Institute of Sport were analysed, from which reference ranges were calculated. To ascertain the stability of reticulocyte profiles during periods of intense physical training, the intra-individual variation of these parameters in 12 iron-replete female athletes over a four month period of training was documented. The precision with which the analyzer measured these parameters was also determined using duplicate samples from 37 female athletes. To establish whether reticulocyte parameters were sensitive to iron deficient erythropoiesis in athletes, reticulocyte profiles of five female athletes diagnosed by medical personnel as having depleted iron stores were compared before and after iron therapy to seven controls. RESULTS: Corpuscular hemoglobin concentration mean (CHCMr) and mean corpuscular volume (MCVr) showed little variation over time in iron-replete females, with 95% of all fluctuations being within 5.8% and 4.3% of original values, respectively. Iron supplementation in athletes with depleted iron stores elicited an increase in CHCMr (p = 0.01), and a decrease in the distributions of reticulocyte volume (RDWr, p = 0.01) and cell hemoglobin concentration (HDWr, p < 0.01). The ratios of reticulocyte to mature cell MCV (p < 0.01) and CHCM (p < 0.01) also changed following iron therapy. No such changes occurred in non-supplemented controls with normal iron stores. CONCLUSIONS: These data lend support to the thesis that monitoring of reticulocyte parameters can be of use in detecting iron deficient erythropoiesis in female athletes.     

Effect of a herbal yeast food supplement and long-distance running on immunological parameters

The effect of a food supplement on immunological parameters of 16 long-distance runners was tested in a randomized, double-blind and placebo-controlled trial. The supplement comprised plasmolysed herbal yeast, malt, honey, and orange juice. No statistically significant differences between the two groups regarding the following variables were detected at three sessions at rest and immediately after a 21 km run: total and differential white blood cell counts, numbers of B- and T-cells and T-subpopulations, concanavalin-A-induced lymphocyte proliferation, serum levels of immunoglobulins, neopterin, IL-2 receptors, beta 2-microglobulin, complement factor b, c4 and c3c, and c1-inactivator. These findings suggest that the effects of the tested food supplement on these parameters are negligible with respect to improvements in the immunological status of long-distance runners. The changes observed immediately after the run had a transient character. In both groups, however, low lymphocyte counts, IgG subclass 2 levels and c1-inactivator levels were noted at rest, which indicate that the immune status of endurance athletes may be affected by training.     

Bone mineral content of cyclically menstruating female resistance and endurance trained athletes

The bone mineral content (BMC) at four sites on the axial and appendicular skeleton was compared among four groups of young adult (age = 17-38 yr) cyclically menstruating athletes (N = 40) who regularly performed either weightlifting resistance exercise (body builders) or nonresistance endurance exercise (runners, swimmers) and an inactive group of females (N = 18) of about equal age. Forearm BMC was measured using single photon absorptiometry at proximal (shaft) and distal sites on the radius. Dual photon absorptiometry was used to measure BMC at the lumbar vertebrae (L2-4) and femur at the femoral neck, Ward's triangle, and greater trochanter. Fat-free body mass (FFBM) was estimated from densitometry. Body builders had greater BMC than swimmers, collegiate runners, recreational runners, and controls. Mean differences in BMC among runners, swimmers, and controls were not significant (P less than or equal to 0.05). FFBM was correlated significantly with BMC (r = 0.35-0.56) at each site in the combined group of athletes (N = 39), whereas total body weight and BMC were correlated significantly at the distal radius site (r = 0.38) only. The results suggest that weight training may provide a better stimulus for increasing BMC than run and swim training.