Individual variation in the erythropoietic response to altitude training in elite junior swimmers

Objectives: Inter-individual variations in sea level performance after altitude training have been attributed, at least in part, to an inter-individual variability in hypoxia induced erythropoiesis. The aim of the present study was to examine whether the variability in the increase in total haemoglobin mass after training at moderate altitude could be predicted by the erythropoietin response after 4 h exposure to normobaric hypoxia at an ambient Po₂ corresponding to the training altitude.

Methods: Erythropoietin levels were measured in 16 elite junior swimmers before and after 4 h exposure to normobaric hypoxia (Fio₂ 0.15, ~2500 m) as well as repeatedly during 3 week altitude training (2100–2300 m). Before and after the altitude training, total haemoglobin mass (CO rebreathing) and performance in a stepwise increasing swimming test were determined.

Results: The erythropoietin increase (10–185%) after 4 h exposure to normobaric hypoxia showed considerable inter-individual variation and was significantly (p<0.001) correlated with the acute erythropoietin increase during altitude training but not with the change in total haemoglobin mass (significant increase of ~6% on average). The change in sea level performance after altitude training was not related to the change in total haemoglobin mass.

Conclusions: The results of the present prospective study confirmed the wide inter-individual variability in erythropoietic response to altitude training in elite athletes. However, their erythropoietin response to acute altitude exposure might not identify those athletes who respond to altitude training with an increase in total haemoglobin mass.

     

Reticulocyte parameters as potential discriminators of recombinant human erythropoietin abuse in elite athletes

This study investigated using reticulocyte (retic) parameters as indirect markers of human recombinant erythropoietin (r-HuEPO) abuse in elite athletes. Absolute reticulocyte count (# retic), the per cell haemoglobin content of reticulocytes (CHr), reticulocyte haemoglobin mass per litre of blood (RetHb) and red blood cell:reticulocyte haemoglobin (RBCHb:RetHb) ratio were assessed using flow cytometry. Venous blood was drawn from 155 elite athletes from six sports during regular training to establish reference ranges (95% confidence interval) for these parameters. The reference ranges were compared with those of a non-athletic population (n = 23), four groups of athletes (n = 24) before and after exposure to simulated altitudes (2,500-3,000 m for 11-23 nights), two groups of elite cyclists (n = 13) before and after four weeks of training at natural altitude (1,780 and 2,690 m), and with those of non-athletic subjects from a separate study (n =24) before and 1-2 days after they were injected with 1,200 U x kg(-1) r-HuEPO over a 9-10 day period. Generally the changes induced by r-HuEPO injection exceeded by approximately 100% the magnitude of the changes associated with natural altitude exposure. Simulated altitude exposure did not significantly alter the reticulocyte parameters. From the sample of 155 non-users and 24 r-HuEPO users, the population mean and variance, as well as the 95% confidence limits for the population mean and population variance, were estimated. Relative to arbitrarily chosen cut-off levels, the confidence limits for the rate of true positives and rate of true negatives were also calculated. Based on the lowest rate of false positives and highest rate of true positives, the best discriminator between r-HuEPO users and non-users was # retic, marginally superior to RBCHb: RetHb ratio and RetHb. At a cut-off for # retic of 221 x 10(9)x L(-1) we could be 95% sure that we would find no more than 7 false positives in every 100,000 tests. We would expect to pick up 51.8% of users, and could be 95% sure of picking up at least 38% of current or recent users. This result highlights the potential power of retic parameters for detecting r-HuEPO abuse among athletes. However, the efficacy of these cut-offs for detecting r-HuEPO abuse is unknown if an athlete is a chronic user or stops using r-HuEPO several weeks before being tested.     

High-altitude training. Aspects of haematological adaptation.

Physical training at high altitude improves performance at high altitude. However, studies assessing performance improvements at sea level after training at higher altitudes have produced ambiguous and inconclusive results. Hypoxia-induced secondary polycythemia is a major contributor to increased work capacity at altitude. The common finding upon exposure to hypoxia is a transient increase in haemoglobin concentration and haematocrit because of a rapid decrease in plasma volume followed by an increase in erythropoiesis per se. Both nonathletes and elite endurance athletes have maximal reticulocytosis after about 8 to 10 days at moderate altitude. Training periods of 3 weeks at moderate altitudes result in individual increase of haemoglobin concentration of about 1 to 4%. A more accentuated increase in haemoglobin can be obtained with longer sojourns at moderate altitude. The normal erythropoietin reaction upon exposure to hypoxia comprises initially increased levels followed by a decrease after about 1 week. Thus, the maintenance of a high erythropoietin concentration is not a prerequisite for a sustained increase in erythrocyte formation at high altitude. The main pharmacological modulator of erythropoietin production seems to be adenosine. But modulators such as growth hormone and catecholamines may also potentiate the effect of hypoxia per se on erythropoietin production. On the other hand, there is a risk that the stress hormones may induce a relative depression of the bone marrow particularly in the early phase of altitude training when the adaptation is minimal and the stress reaction is most accentuated. The most important 'erythropoiesis-specific' nutrition factor is iron availability which can modulate erythropoiesis over a wide range in humans. Adequate iron stores are a necessity for haematological adaptation to hypoxia. However, at moderate altitude, there is a need for rapid mobilisation of iron and even if the stores are normal there is a risk that they cannot be mobilised fast enough for an optimal synthesis of haemoglobin. Data from healthy athletes training at moderate altitudes suggest a true increase in haemoglobin concentration of about 1% per week. Complete haematological adaptation occurred when sea level residents have similar haemoglobin concentrations at moderate altitude compared with residents. The normal difference in haemoglobin concentrations can be estimated to be about 12% between permanent residents at sea level and at 2500m above sea level. This difference indicates a necessary adaptation time of about 12 weeks. If the training period at moderate altitude must be shorter, several sojourns at short intervals are recommended. The important factor in haematological adaptation in athletes at moderate altitude is hypoxia.(ABSTRACT TRUNCATED AT 400 WORDS)     

Time course of the hemoglobin mass response to natural altitude training in elite endurance cyclists

To determine the time course of hemoglobin mass (Hb_mass) to natural altitude training, Hb_mass, erythropoietin [EPO], reticulocytes, ferritin and soluble transferrin receptor (sTfR) were measured in 13 elite cyclists during, and 10 days after, 3 weeks of sea level (n=5) or altitude (n=8, 2760 m) training. Mean Hb_mass, with a typical error of ～2%, increased during the first 11 days at altitude (mean ± standard deviation 2.9 ± 2.0%) and was 3.5 ± 2.5% higher than baseline after 19 days. [EPO] increased 64.2 ± 18.8% after 2 nights at altitude but was not different from baseline after 12 nights. Hb_mass and [EPO] did not increase in sea level. Reticulocytes (%) were slightly elevated in altitude at Days 5 and 12 (18.9 ± 17.7% and 20.4 ± 25.3%), sTfR was elevated at Day 12 (18.9 ± 15.0%), but both returned to baseline by Day 20. Hb_mass and [EPO] decreased on descent to sea level while ferritin increased. The mean increase in Hb_mass observed after 11 days (～300 h) of altitude training was beyond the measurement error and consitent with the mean increase after 300 h of simulated live high:train low altitude. Our results suggest that in elite cyclists, Hb_mass increases progressively with 3 weeks of natural altitude exposure, with greater increases expected as exposure persists.     

Screening for haematological and iron-related abnormalities in elite athletes—Analysis of 576 cases

The aim of this prospective, cohort study was to determine the clinical and performance related utility of haematological and iron-related screening in elite athletes. Three hundred and three male and 273 female elite athletes underwent routine medical screening over a three-year period. In association with a standard medical consultation, a full blood count and iron-related variables were measured. Ten male athletes had a serum ferritin less than 30 ng/mL and satisfied AIS criteria for iron supplementation. In only one case was a disorder identified which was not expected following the clinical history and examination. Fifty-two female athletes had a serum ferritin less than 30 ng/mL and satisfied AIS criteria for iron supplementation. In the females, there were no instances in which a medical condition was identified which was not expected following the clinical history and examination. In both groups, clinically non-significant abnormalities were generally minor or isolated reductions in haemoglobin and/or haematocrit, and alterations in red cell parameters or single measures of iron status. Conclusion: Screening for haematological and iron-related abnormalities in athletes has a low yield. Due to the critical nature of the effects of anaemia and low serum ferritin on some aspects of performance it is reasonable to perform a haemoglobin and a serum ferritin on male and female athletes entering an elite training program. Isolated abnormalities which are close to the limits of their normal ranges and not accompanied by symptoms or signs of illness can almost certainly be ignored.     

The 11+ Kids warm-up programme to prevent injuries in young Iranian male high-level football (soccer) players: A cluster-randomised controlled trial

ObjectiveTo assess the effectiveness of the 11+ Kids warm-up programme regarding injury reduction in male high-level children’s football players.DesignCluster-randomised controlled trial.MethodMale youth football teams of Iran’s high-level football schools were invited to participate. Inclusion criteria were: teams are competing in the highest league of their province; players are between 7 and 14 years old; regular training takes place at least twice per week. Teams were excluded if they used an injury prevention measure.Participating clubs were randomised to an intervention (INT, N = 20 teams) and a control group (CON, N = 22 teams), stratified by the number of teams and the age group. The groups were blinded against each other. The follow-up period was one season (9 months). INT replaced their warm-up by 11+ Kids. CON performed a standard warm-up programme. The primary outcome was the injury incidence density (injuries per 1000 h of football exposure), compared between groups by incidence rate ratios (RR).ResultsIn total, 64,047 h of football exposure of 962 players (INT = 443 players, 31,934 h of football, CON = 519 players, 32,113 h of football) were recorded. During the study, 90 (INT = 30; CON = 60) injuries occurred. The overall injury incidence density in INT was reduced by 50% compared to CON (RR 0.50; 95%-CI 0.32, 0.78). No injuries occurred during the execution of the intervention exercises.ConclusionsThe 11+ Kids reduces injuries in high-level children’s football players, thus supporting player health and potentially performance and player development.     

Reticulocytes in sports medicine

Reticulocytes are the transitional cells from erythroblasts to mature erythrocytes. Reticulocytes are present in blood for a period of 1-4 days and can be recognized by staining with supravital dyes, such as new methylene blue, or fluorescent markers, which couple residual nucleic acid molecules, a hallmark of the immature forms of erythrocytes. Although reticulocytes could be counted through a microscope (there is a standard of International Committee for Standardisation in Haematology for manual counting), this method is reported to be time consuming, inaccurate and imprecise. The integration of the reticulocyte count in automated haematology systems allowed the widespread use of these parameters, although the lack of calibration material and different markers, technologies and software used in automated systems could engender discrepancies among data obtained from different analytical systems.The importance of reticulocytes in sports medicine derives from their sensitivity, the highest among haematology parameters, in identifying the bone marrow stimulation, especially when recombinant human erythropoietin is fraudulently used. Automated systems are also able to supply information on volume, density and the haemoglobin content of reticulocytes.Some of the related parameters are also used in algorithms for identifying abnormal stimulation of bone marrow as reticulocytes haematocrit. The pre-analytical variability of reticulocytes (transportation, storage, biological variability) should be taken into account in sports medicine also. Reticulocytes remain stable for almost 24 hours at 4 degrees C from blood drawing, they are affected by transportation, and biological variability is not high in general. It could be remarked, however, that the intra-individual variability is high when compared with other haematological parameters such as haemoglobin and haematocrit. The intervals of data reported in athletes are very similar to reference intervals characterizing the general population.The reticulocyte count shows some modifications after training and during the competition season. The variability induced by exercise cannot be overlooked since the so-called haematological passport, a personal athlete's document in which haemoglobin and other parameters are registered, may be introduced by sports federations. Exposure to naturally high altitude and 'living high-training low' programmes determined contentious results on reticulocytes. Simulated high altitude induced by intermittent hypobaric hypoxia does not modify reticulocytes, despite an increase in erythropoietin serum concentration. The variability among athletes competing in different sport disciplines is apparently limited. The knowledge of the behaviour of reticulocytes in training and competitions is crucial for defining their role in an antidoping control context. It is important for sport physicians and clinical pathologists to know the reticulocyte variability in the general population and in athletes, the pre-analytical warnings, the different methodologies for counting reticulocytes and the derived parameters automatically available, and, finally, the possible influence of training, competitions, type of sport and altitude.     

Self-reported throwing volumes are not a valid tool for monitoring throwing loads in elite Australian cricket players: An observational cohort study

ObjectivesTo determine the concurrent validity of player self-reported and independently observed throwing volume. Examine whether sex, playing position, or time to upload self-reported data post training influences the accuracy of self-reported throwing loads.DesignCross-sectional cohort study.MethodsA total of 8 female and 18 male elite cricket players participated in the study. Overarm throws from 12 training sessions during the 2020–21 cricket year were observed. Player self-reported throwing volume data were retrieved post training, with the time difference between session completion and self-reported data upload recorded.ResultsA moderate positive correlation was found between self-reported and observed throwing loads (rho = 0.65), however only 22 % of players reported values within a 10 % level of error. Players reported a mean (SD) absolute inaccuracy of 11.17 (9.77) throws, and a mean (SD) relative inaccuracy of 24.76 (16.04) percent. Sex did not influence reporting accuracy (p = 0.41). Females tended to upload self-reported data the day of training, whereas men report the day following. Players who uploaded their data greater than one day after training were the most inaccurate with a mean relative inaccuracy of 36 %.ConclusionsWhile there is a clear relationship between observed and self-reported throwing volumes, the findings of this study question the validity of using player self-reported throwing load as a marker of true throwing loads with most players recording in excess of 10 % error. High performance staff and players should consider whether the current accuracy of self-reported throwing load justifies the additional reporting burden on the players during training.     

Red blood cell profile of elite olympic distance triathletes. A three-year follow-up

The purpose of this study was to monitor general and individual changes in hematological variables during long-term endurance training, detraining and altitude training in elite Olympic distance triathletes. Over a period of three years, a total of 102 blood samples were collected in eleven (7-male and 4 female) elite Olympic distance triathletes (mean +/- SD; age = 26.4 +/- 5.1 yr; VO(2) max = 67.9 +/- 6.6 ml/min/kg) for determination of hemoglobin (Hb), hematocrit (Hct), red blood cell count (RBC), Mean corpuscular hemoglobin (MCH), Mean corpuscular hemoglobin content (MCHC), Mean corpuscular volume (MCV) and plasma ferritin. The data were pooled and divided into three periods; off-season, training season and race season. Blood samples obtained before and after altitude training were analyzed separately. Of all measured variables only RBC showed a significant decrease (p < 0.05) during the race season compared to the training season. Hematological values below the lower limit of the normal range were found in 46 % of the athletes during the off-season. This percentage increased from 55 % during the training season to 72 % of the athletes during the race season. Hemoglobin and ferritin values were most frequently below the normal range. There was a weak correlation between Hb levels and VO(2) max obtained during maximal cycling (r = 0.084) and running (r = 0.137) tests. Unlike training at 1500 m and 1850 m, training at an altitude of 2600 m for three weeks showed significant increases in Hb (+ 10 %; p < 0.05), Hct (+ 11 %; p < 0.05) and MCV (+ 5 %; p < 0.05). Long-term endurance training does not largely alter hematological status. However, regular screening of hematological variables is desirable as many athletes have values near or below the lower limit of the normal range. The data obtained from altitude training suggest that a minimum altitude (>2000 m) is necessary to alter hematological status.     

Iron deficiency in adolescent female dancers.

The iron balance of 25 adolescent dancers and 23 control females of the same age were studied. The concentrations of fasting blood haemoglobin, serum iron, serum transferrin and serum ferritin were determined. Iron supplementation (ferrous sulphate corresponding to 100 mg of elemental iron per day) was instigated if body iron stores were low (serum ferritin less than 30 micrograms.l-1). Blood samples were drawn again after ten weeks. Low haemoglobin concentration (blood haemoglobin less than 125 g.l-1) was more prevalent among dancers than among control subjects. Reduced iron stores as well as completely absent iron stores (serum ferritin concentration less than 12 micrograms.l-1) were equally common in both groups (25% of the subjects). Iron supplementation reduced the number of anaemic girls from 16 to 4 and the highly significant difference in haemoglobin level between the treated and untreated groups disappeared. Ten weeks of iron therapy was not, however, long enough to increase iron stores.     

Changes in haematological parameters and iron metabolism associated with a 1600 kilometre ultramarathon

OBJECTIVE: To investigate haematological variations and iron related changes in the serum of participants in a 1600 kilometre ultramarathon run. PARTICIPANTS: Seven male and two female participants in a 1600 km foot race. METHODS: Blood samples were obtained from the participants before, after four and 11 days of running, and at the end of the event. Samples were analysed by standard methods for haemoglobin, packed cell volume, total red cell count, mean red cell volume, mean red cell haemoglobin, total white cell count and differential, platelets, reticulocytes, iron, ferritin, total iron binding capacity, percentage transferrin saturation, haptoglobin, and bilirubin and corrected for changes in plasma volume. RESULTS: The following variables decreased during the event (p < 0.05): haemoglobin, packed cell volume, mean red cell volume, percentage lymphocytes, percentage monocytes, serum iron, total iron binding capacity, and percentage transferrin saturation. Increases (p < 0.05) were found in plasma volume, total red cell count (day 4 only), total white cell count, percentage and absolute numbers of neutrophils and reticulocytes, absolute numbers of lymphocytes and monocytes (day 4 only), absolute numbers of eosinophils (day 11 and race end), absolute numbers of basophils (race end only), platelets, ferritin, haptoglobin, and bilirubin (day 4 only). CONCLUSION: Ultramarathon running is associated with a wide range of changes in haematological parameters, many of which are related to the normal acute phase response to injury. These should not be confused with indicators of disease.


     

Influence of iron status and iron supplements on natural killer cell activity in trained women runners

Twenty-two trained women runners (.VO2peak 48.1 + 1.2 ml x kg -1 x min -1) were divided into an iron supplement (n = 13) or placebo group (n = 9) based on initial serum ferritin concentration (24.2 +/- 2.9 and 58.5 +/- 4.0 microg x l -1, respectively). Exercise consisted of a 35-min run (80 % .VO2peak) and was performed at week 0 (WK0), after two weeks of intensified training (WK2) and after eight weeks recovery training (WK10). The eight weeks recovery training were concomitant with subjects taking iron supplements or placebo in a double blind fashion. Concentrations of serum ferritin, serum iron and total iron binding capacity were assessed pre-exercise and complete blood count, natural killer cell activity (NKACT), and cell surface markers for CD3+, CD4+, CD3+,CD8+, CD3-, CD16+, CD56+ cells were determined both pre- and post-exercise. Serum ferritin concentrations were significantly (p < 0.05) increased on WK10 compared to WK2 (time effect). NKACT (%lysis) and NK cell number was lower (p < 0.05) at WK0 for supplement (42.9 +/- 1.9 % and 305.5 +/- 15.0 x 10 6 x l -1, respectively) compared to placebo groups (50.9 +/- 2.0 and 406.1 +/- 25.6, respectively). Two weeks of intensified training did not alter indices of host defense. In conclusion, NKACT and NK cell numbers were lower in subjects with greater body mass and lower iron stores (p < 0.05), but were not significantly altered after two weeks of intensified training or when serum ferritin levels increased.     

An audit of clinically relevant abnormal laboratory parameters investigating athletes with persistent symptoms of fatigue

The aim of this audit was to assess the yield of a selection of laboratory tests as part of the clinical assessment of the fatigued athlete. Clinical charts and blood test results of fifty consecutive athletes who presented with the primary complaint of fatigue were retrospectively reviewed. Blood tests results reviewed were: haematology (haemoglobin, red cell count, mean cell volume, mean cell haemoglobin content, platelets, white cell count, differential white cell count); erythrocyte sedimentation rate; serum biochemistry (urea, creatinine, electrolytes, urate, glucose, liver function tests, albumin, globulin); blood iron status (serum iron, total iron binding capacity, percent transferring saturation, and ferritin concentration); thyroid stimulating hormone; and immune measures (Epstein–Barr virus serology, cytomegalovirus serology). We identified only 3 abnormal results that contributed to the diagnosis of medical disease as a cause for fatigue. Laboratory testing identified 2 fatigued female athletes with serum ferritin concentration between 15 μg L⁻¹ and 20 μg L⁻¹ plus two of the other criteria of iron concentration (serum iron <10 μmol L⁻¹, iron binding capacity >68 μmol L⁻¹, or transferrin saturation <15%). We concluded that the yield from a selection of blood tests investigating fatigued athletes was low. Future study is needed to further define the role of laboratory testing and to study whether low iron stores in the absence of anaemia is related to symptoms in fatigued athletes.     

The effects of physical exercise on the concentrations of ferritin and transferrin receptor in plasma of female judoists

The aim of the study was to assess the effect of physical exercise on the changes in concentrations of ferritin and soluble transferrin receptor (sTfR) in plasma in course of 10 consecutive days of a training camp. Ten female elite judoists, aged 17-23 years, participated in the study. Mean concentration of ferritin for the 10 day period was 62.8 x 1.633(+/-1) microg/l, the within-subject, day-to-day variability being very high (13-75%). Ferritin concentrations were significantly correlated with the training load on the preceding day (r = 0.397; p < 0.001). Mean level of sTfR was 2.56 x 1.291(+/-1) mg/l and its within-subject variability was much lower (4-16%). Although the training loads had an effect on the intravascular hemolysis as indicated by a significant, negative correlation between load scores and haptoglobin concentration (r = -0.282; p < 0.01), the latter was not correlated significantly with sTfR levels. It was concluded that the soluble transferrin receptor is a more stable indicator of iron status under high training loads since, unlike ferritin, it does not respond to the workload on the preceding day. Moreover, the intravascular hemolysis observed in athletes does not affect the sTfR levels in plasma.     

Monitoring altitude acclimatization--a case study of an élite woman athlete.

A simple study monitoring altitude acclimatization, which is not intrusive to the athlete's training, is described. Particular attention is drawn to the change in production of lactate in response to steady state exercise, before and after altitude. The results suggest that a more thorough assessment of aerobic ability at altitude is required than that described in the British Association of Sports and Exercise Science (BASES) guidelines. It is also relevant to note that elevations in haemoglobin, promoted by altitude, can mask iron abnormalities. It is therefore recommended to assay for iron in addition to haemoglobin.     

Combined training in patient with aids: improved quality of life and preserved BDNF

Objectives

This study aims to investigate the impact of combined exercise training on selected health status measures and quality of life in patients with AIDS

Material and methods

Thirty AIDS patients were randomly divided into two groups of combined exercise training on one hand and control on the other. Combined training consisted of aerobic and resistance exercises for a duration of 12 weeks (three sessions/week). Aerobic training consisted of walking or running on a treadmill with increasing intensity from 40 to 65% of maximal heart rate for 30–60 min. Resistance sessions were made of leg press, lateral pull down, biceps curl and chest press, with 40–65% of 1-RM, two to four sets of 12–20 repetitions. Blood samples were taken from patients around 24 h before the first and 72 h after the last training sessions and cluster of differentiation four cells (CD4), serum brain-derived neurotrophic factor (BDNF), and viral load levels as well as the quality of life were assessed

Results

The results showed that although combined exercise training did not affect CD4 and viral load, quality of life increased significantly in the training group (p?=?0.04). Moreover, BDNF significantly decreased in the control group but not in the training group (p?=?0.03)

Conclusions

These findings suggest that combined exercise training over 3 months resulted in increased quality of life while preventing reductions in BDNF levels in AIDS patients, while no changes in viral load and CD4 count have been noticed

     

Predictive modeling of the ratings of perceived exertion during training and competition in professional soccer players

ObjectivesEvaluate the ability of predicting the ratings of perceived exertion from the external load variables in professional soccer players through a chronological perspective (i.e., past features values are considered additional features) through machine learning models by considering the playing position.DesignProspective cohort study.MethodsThirty-eight elite soccer players aged 19-27 years were observed during 151 training sessions, 44 matches across a full season. External load variables (58 derived from Global Positioning System and 30 from accelerometers) and the internal load derived from ratings of perceived exertion were collected for each player and each session and match. Machine learning models (linear regression, K-NN, decision trees, random forest, elastic net regression, XGBoost) were compared and interpreted in order to deepen the relationship between external load variables and ratings of perceived exertion according to the player position in a predictive perspective.ResultsApplication of the machine learning models on the dataset provided enough predictive power to reduce the Root Mean Squared Error of 60 % from dummy predictions. The most accurate models (Root Mean Squared Error ≈ 1.1 for random forest and = 1 for XGBoost) highlighted a memory effect in subsequent ratings of perceived exertion values. Past ratings of perceived exertion values over one month were the strongest predicting factors of ratings of perceived exertion as compared to various external load indicators.ConclusionsThe tree-based machine learning models showed statistically significant predictive ability, indicating valuable information for understanding the training load responses based on ratings of perceived exertion changes.     

Analysis of jump load during a volleyball season in terms of player role

ObjectivesThe aim of this study was to analyze the jump load performed by top-level volleyball players during an entire training season in terms of the player role, training period, type of daily training, and quality of opposition in the subsequent match.DesignLongitudinal panel observational study.MethodsThe total number of jumps performed by players was recorded through 174 training days distributed in 32 weeks during the 2016/2017 season (pre-season, 5 weeks; in-season, 27 weeks). The players role were classified as middle-blocker, outside-hitter, opposite and setter (the libero was omitted). A generalized mixed linear model was performed (with Bonferroni post hoc test at p < 0.05) to assess the effect of training variables and the repeated-measures data of players’ jumps along various training days. Additionally, the effect sizes at 95% confidence intervals were calculated to compare the jump load between players’ role and training variables.ResultsThe results showed a significant and moderate higher amount of jumps performed by middle-blockers regardless the type of macro- or micro-cycle, the micro-cycle phase, the type of training and the quality of match opposition. Contrarily, the setter performs the least jump load in all variables analyzed. Only the players’ role, macro-cycle and micro-cycle phase had significant effects on the player's jump load variation along the season.ConclusionsThis information could be useful to guide the monitoring and preparation process for coaches and physical trainers. These values allow differentiating between players’ role and could be used as references values in order to avoid injuries whereas performance increase along the season.     

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.     

Women at the Military Academies

In brief: This study compared three stages of iron deficiency (iron depletion, iron deficiency erythropoiesis, and iron deficiency anemia) in athletes and controls immediately after menstruation and at midcycle. All athletes had subnormal serum ferritin levels at both test periods, indicating stage 1 iron deficiency. The control group's serum ferritin levels were normal. Two athletes were stage 2 iron deficient, but no athletes or control subjects were in the third stage of iron deficiency. This study shows that stage 1 and 2 iron deficiency may exist in female athletes even in the absence of anemia. Therefore, sports programs should provide nutrition counseling, but indiscriminate use of oral iron supplements should be discouraged.