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At least 667 records · Page 37Linked to original sources
PubMed1994

Osteoarthritis of weight bearing joints of lower limbs in former élite male athletes.

OBJECTIVE: To compare the cumulative 21 year incidence of admission to hospital for osteoarthritis of the hip, knee, and ankle in former élite athletes and control subjects. DESIGN: National population based study. SETTING: Finland. SUBJECTS: 2049 male athletes who had represented Finland in international events during 1920-65 and 1403 controls who had been classified healthy at the age of 20. MAIN OUTCOME MEASURES: Hospital admissions for osteoarthritis of the hip, knee, and ankle joints identified from the national hospital discharge registry between 1970 and 1990. RESULTS: Athletes doing endurance sports, mixed sports, and power sports all had higher incidences of admission to hospital for osteoarthritis than controls. Age adjusted odds ratios compared with controls were 1.73 (95% confidence interval 0.99 to 3.01, P = 0.063) in endurance, 1.90 (1.24 to 2.92, P = 0.003) in mixed sports athletes, and 2.17 (1.41 to 3.32, P = 0.0003) in power sports athletes. The mean age at first admission to hospital was higher in endurance athletes (70.6) than in other groups (58.2 in mixed sports, 61.9 in power sports, and 61.2 in controls). Among the 2046 respondents to a questionnaire in 1985, the odds ratios for admission to hospital were similar in all three groups after adjusting for age, occupation, and body mass index at 20 (2.37, 2.42, 2.68). CONCLUSIONS: Athletes from all types of competitive sports are at slightly increased risk of requiring hospital care because of osteoarthritis of the hip, knee, or ankle. Mixed sports and power sports lead to increased admissions for premature osteoarthritis, but in endurance athletes the admissions are at an older age.

Adult↗
PubMed1989

Electrocardiographic findings in male veteran endurance athletes.

Twenty male veteran endurance runners and 20 controls underwent resting, exercise, and ambulatory electrocardiography. Four athletes and three controls satisfied voltage criteria for left ventricular hypertrophy. The PR interval was longer in the athletes and they had longer mean (SD) treadmill exercise times (19 (4) v 16 (2) min) than the controls. Four athletes but no controls had greater than 2 mm downsloping ST segment depression during exercise. During 48 hour ambulatory electrocardiography the athletes had a consistently lower heart rate but maintained a circadian variation. Profound bradycardia (less than 35 beats/min) occurred in eight athletes but only one control. Eight athletes and two controls had asystolic pauses ranging from 1.8 to 15 seconds. Six athletes had first degree heart block, four had Mobitz II second degree block, and three had complete heart block. Most conduction abnormalities occurred at night and resolved during exercise. Ventricular ectopic activity was not significantly different between the groups. Thus heart block patterns and profound bradycardia are more frequent in older athletes than their youthful counterparts.

Age Factors↗
PubMed1999

Insulin action on heart and skeletal muscle glucose uptake in weight lifters and endurance athletes.

There are no studies comparing myocardial metabolism between endurance- and resistance-trained athletes. We used 2-deoxy-2-[18F]fluoro-D-glucose and positron emission tomography combined with the euglycemic hyperinsulinemic clamp technique to compare the ability of insulin to stimulate myocardial, skeletal muscle, and whole body glucose uptake between weight lifters (n = 8), endurance athletes (n = 8), and sedentary men (n = 9). Maximal aerobic power (ml. kg- 1. min- 1) was higher in the endurance athletes (71 +/- 2, P < 0.001) than the weight lifters (42 +/- 2) and the sedentary men (42 +/- 2). Skeletal muscle glucose uptake (micromol. kg muscle- 1. min- 1) was enhanced in the endurance athletes (125 +/- 16, P < 0.01) but was similar in weight lifters (59 +/- 12) and sedentary (63 +/- 7) men. The rate of glucose uptake per unit mass of myocardium (micromol. kg- 1. min- 1) was similarly decreased in endurance athletes (544 +/- 50) and weight lifters (651 +/- 45) compared with sedentary men (1,041 +/- 78, P < 0.001 vs. endurance athletes and weight lifters). Both groups of athletes had increased left ventricular mass. Consequently, total left ventricular glucose uptake was comparable in all groups. These data demonstrate that aerobic but not resistance training is associated with enhanced insulin sensitivity in skeletal muscle. Despite this, cardiac changes are remarkably similar in weight lifters and endurance athletes and are characterized by an increase in left ventricular mass and diminished insulin-stimulated glucose uptake per heart mass.

Adult↗
PubMed1995

Arterial compliance may influence baroreflex function in athletes and hypertensives.

The present study investigated arterial compliance as a possible influence on mean arterial pressure-heart rate (MAP-HR) reflex function in athletes and hypertensives. Aortic stiffness and systemic arterial compliance (SAC) were estimated in 25 elite male athletes and 25 age-matched sedentary controls. Blood pressure did not vary between groups, but SAC was higher in the athletic compared with the sedentary group (0.46 +/- 0.04 vs. 0.37 +/- 0.02 arbitrary compliance units; P = 0.03). In five hypertensives and six age-matched normals and in a subgroup of seven athletes and seven age-matched controls the sigmoidal MAP-HR reflex was assessed using phenylephrine and nitroprusside. In athletes compared with sedentary subjects MAP-HR reflex sensitivity was the same; however, the maximum tachycardia in response to blood pressure reduction was lower in the athletic group (87.1.1 +/- 3.7 vs. 97.1 +/- 2.9 beats/min; P = 0.05). Athletes had a higher blood pressure corresponding to 95% of the HR range (64.2 +/- 3.2 vs. 54.0 +/- 2.1 mmHg; P = 0.02), but there was no difference in the blood pressure corresponding to 5% of the HR range. The blood pressure excursion necessary to traverse the baroreceptor transducer range (MAPd) was therefore less in athletes compared with normals. The beta-index of aortic stiffness correlated closely with MAPd (R = 0.70; P < 0.01). In hypertensives reflex sensitivity was reduced, the minimum HR was elevated, and the MAPd was 56% greater compared with normals.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Histochemical and enzymatic characteristics of skeletal muscle in master athletes.

Many older athletes are capable of endurance performances equal to those of young runners who have higher maximal O2 uptakes (VO2max). To determine whether this is a result of differences in skeletal muscle characteristics, gastrocnemius muscle biopsy samples were obtained from eight master athletes [aged 63 +/- 6 (SD) yr] and eight young (aged 26 +/- 3 yr) runners. The young runners were matched with the master athletes for 10-km running performance and for their volume, pace, and type of training. Despite similar 10-km run times, VO2max was 11% lower (P less than 0.05) in the master athletes. Fiber type distribution did not differ between groups, with both groups having 60% type I and very few type IIb fibers. Succinate dehydrogenase and beta-hydroxyacyl-CoA dehydrogenase activities, however, were 31 and 24% higher in the master athletes compared with the matched young runners, whereas lactate dehydrogenase activity was 46% lower (all P less than 0.05). The capillary-to-fiber ratio was also greater in the master athletes; however, capillary density was similar in the two groups, because of the master athletes' 34% larger (P less than 0.05) type I fibers. These differences in skeletal muscle characteristics may explain the master athletes' ability to perform as well as some young runners despite having a lower VO2max.

Adult↗
PubMed1990

Cyclic ovarian function in recreational athletes.

In 17 female recreational athletes, ovarian function was monitored using daily hormone measurements and serial ultrasound determinations. Whereas 11 out of 13 women of a control group showed estradiol (E2) maxima beyond 470 pmol/l, progesterone (P4) maxima of 19 nmol/l or more, and a luteal phase length of 9 days or more, only 10 out of 17 athletes satisfied these criteria. Six athletes showed disturbed follicular development, and one athlete showed luteal phase disturbance. Both athletes with disturbed menstrual function (n = 7) and athletes fulfilling the above-mentioned minimal criteria (n = 10) had lower E2 concentrations in all phases of the menstrual cycle (P less than 0.05). P4 concentrations were significantly decreased in the group with disturbed menstrual function (P less than 0.05). Maximal aerobic capacity in the two athlete groups was similar. Neither athlete group showed the expected increase in caloric intake compared with the sedentary controls. It is concluded that recreational running is associated with altered ovarian function. Inadequate nutritional adaptation may be a contributing factor.

Adult↗
PubMed1991

Electrocardiographic findings in athletic students and sedentary controls.

We have investigated resting electrocardiograms from 1,299 athletic students taken in the same laboratory during the years 1973-1982 and compared them with electrocardiograms recorded in 151 age- and sex-matched sedentary controls. Fifty-two parameters were recorded for each electrocardiogram and computerized. We found that athletic students had a significant lower heart rate, longer PQ time and a prolonged QTc compared to control subjects. Athletes had higher maximal Q amplitudes in precordial leads, higher R in V1, and higher indices of right ventricular hypertrophy (RV1 + SV5) and left ventricular hypertrophy (Sokolow-Lyon and Grant indices). Furthermore, the athletes had higher maximal ST elevation and higher maximal T wave amplitudes in precordial leads. Sinus bradycardia was more frequent in athletes. All control subjects were in sinus rhythm whereas 0.9% of the athletes had other rhythms (nodal, coronary sinus or wandering pacemaker). Athletes and control subjects did not differ significantly with regard to premature beats, atrioventricular block, bundle branch block or the Wolff-Parkinson-White pattern. We conclude that training induces significant changes in heart rate, conduction times, ST elevation. QRS and T voltage, slow rhythm disturbances and atrioventricular and sinoatrial block were infrequent in the resting electrocardiogram taken in the supine position and disappeared immediately on sitting and during exercise. Training-induced electrocardiographic changes may partly be due to alterations in autonomic tone and partly to structural changes in the myocardium. Different normal criteria for left ventricular hypertrophy may be warranted in athletes.

Adolescent↗
PubMed1993

Mechanism of enhanced insulin sensitivity in athletes. Increased blood flow, muscle glucose transport protein (GLUT-4) concentration, and glycogen synthase activity.

UNLABELLED: We examined the mechanisms of enhanced insulin sensitivity in 9 male healthy athletes (age, 25 +/- 1 yr; maximal aerobic power [VO2max], 57.6 +/- 1.0 ml/kg per min) as compared with 10 sedentary control subjects (age, 28 +/- 2 yr; VO2max, 44.1 +/- 2.3 ml/kg per min). In the athletes, whole body glucose disposal (240-min insulin clamp) was 32% (P < 0.01) and nonoxidative glucose disposal (indirect calorimetry) was 62% higher (P < 0.01) than in the controls. Muscle glycogen content increased by 39% in the athletes (P < 0.05) but did not change in the controls during insulin clamp. VO2max correlated with whole body (r = 0.60, P < 0.01) and nonoxidative glucose disposal (r = 0.64, P < 0.001). In the athletes forearm blood flow was 64% greater (P < 0.05) than in the controls, whereas their muscle capillary density was normal. Basal blood flow was related to VO2max (r = 0.63, P < 0.05) and glucose disposal during insulin infusion (r = 0.65, P < 0.05). The forearm glucose uptake in the athletes was increased by 3.3-fold (P < 0.01) in the basal state and by 73% (P < 0.05) during insulin infusion. Muscle glucose transport protein (GLUT-4) concentration was 93% greater in the athletes than controls (P < 0.01) and it was related to VO2max (r = 0.61, P < 0.01) and to whole body glucose disposal (r = 0.60, P < 0.01). Muscle glycogen synthase activity was 33% greater in the athletes than in the controls (P < 0.05), and the basal glycogen synthase fractional activity was closely related to blood flow (r = 0.88, P < 0.001). IN CONCLUSION: (a) athletes are characterized by enhanced muscle blood flow and glucose uptake. (b) The cellular mechanisms of glucose uptake are increased GLUT-4 protein content, glycogen synthase activity, and glucose storage as glycogen. (c) A close correlation between glycogen synthase fractional activity and blood flow suggests that they are causally related in promoting glucose disposal.

Adult↗
PubMed2005

Scapular position and orientation in throwing athletes.

BACKGROUND: Despite the recognized importance of proper 3-dimensional motion of the scapula in throwers, minimal research has quantified scapular position and orientation in throwing athletes. HYPOTHESIS: Throwing athletes exhibit scapular position and orientation differences when compared to nonthrowing control subjects. STUDY DESIGN: Descriptive laboratory study. METHODS: Scapular position and orientation during scapular plane humeral elevation were assessed with electromagnetic tracking in a group of 21 throwing athletes and 21 control subjects. Scapular upward/downward rotation, internal/external rotation, anterior/posterior tipping, elevation/depression, and protraction/retraction were assessed. RESULTS: The throwing athletes demonstrated significantly increased upward rotation, internal rotation, and retraction of the scapula during humeral elevation. No differences in anterior/posterior tipping and elevation/depression were present. CONCLUSIONS: The results indicate that throwing athletes have scapular position and orientation differences compared to non-throwing athletes. This suggests that throwers develop chronic adaptation for more efficient performance of the throwing motion. CLINICAL RELEVANCE: Clinicians evaluate scapular position, orientation, and movement in throwing athletes as part of the evaluation of shoulder injuries associated with the throwing motion. The current study provides clinicians with an understanding of the types of adaptations that may be observed in normal, healthy throwing athletes.

Adaptation, Physiological↗
PubMedDate not supplied

The effect of ankle stabilizers on athletic performance. A randomized prospective study.

The ankle is the site of more than one third of all injuries that occur to male basketball players. Although ankle bracing may prevent injury, many players believe that braces restrict athletic performance. This belief discourages use of braces and obviates the injury protection that bracing provides. The objectives of this study were to 1) determine whether athletic performance (in four basketball-related activities) was affected by three ankle brace designs (Universal, Kallassy, and Air-Stirrup ankle training brace), 2) determine whether specific braces are better for specific athletic activities, and 3) determine whether athletic performance changes with brace use. Twelve high school basketball players wore each brace type while vertical jumping, standing long jumping, cone running, and 18.3-meter shuttle running at two test times (initially and after 1 week of acclimation). Our data showed that these braces had no significant effects on athletic performance. No brace affected athletic performance in one specific activity more than another, and athletic performance did not change with brace use. We concluded that prophylactic ankle bracing does not inhibit athletic performance.

Adaptation, Physiological↗
PubMed2004

Diurnal profiles of testosterone and pituitary hormones suggest different mechanisms for menstrual disturbances in endurance athletes.

The aim of this study was to evaluate the diurnal pattern of testosterone and pituitary hormones in endurance female athletes with different types of menstrual disorder. Age- and body mass index-matched groups of endurance athletes with amenorrhea (n = 10) and oligomenorrhea (n = 6), regularly cycling athletes (n = 8), and sedentary controls (n = 8) were compared with respect to 24-h hormonal profiles of testosterone, LH, prolactin (PRL), GH, insulin, IGF binding protein 1 (IGFBP-1), and cortisol. The 24-h hormone profiles in amenorrheic athletes were characterized by decreased LH pulsatility and peak amplitude of PRL and increased baseline levels of GH and cortisol. However, oligomenorrheic athletes displayed a significantly different pattern with higher diurnal testosterone secretion than all other groups. Furthermore, LH, PRL, GH, and cortisol secretions were comparable with regularly menstruating subjects. In the combined group of athletes with menstrual disturbances, diurnal secretions of testosterone, LH, and PRL were positively, whereas cortisol was negatively correlated with the number of menstruations the last year. Although this could be explained by a gradual inhibition of the hypothalamic-pituitary-gonadal axis, our results indicate that the symptoms of amenorrhea and oligomenorrhea may reflect two hormonally distinct conditions. Thus, amenorrheic athletes displayed a hormonal pattern in agreement with hypothalamic inhibition due to energy deficiency, whereas oligomenorrheic athletes demonstrated increased diurnal secretion of testosterone, suggesting a different mechanism, e.g. essential hyperandrogenism.

Adult↗
PubMed1994

Healthy lifestyles of former Finnish world class athletes.

Recently, Sarna et al. (Med. Sci. Sports Exerc. 25:237-244, 1993) reported increased mean life expectancy in former world class athletes. Because lifestyle is associated with longevity, we have examined whether health habits of former Finnish male athletes (N = 1274; present mean age: 57.5, range: 36-94 yr) differed from those of noncompetitive referents (N = 788; mean age: 55.7, range: 39-87 yr). The athletes had represented Finland in international competitions in endurance (N = 177), power (N = 454), or other ("mixed") events (N = 643) from 1920-1965. Data on physical characteristics, sociodemographic factors, and health habits were obtained from questionnaires. All dependent variables in an analysis of covariance and in a logistic regression analysis were adjusted for age and occupation. Both leisure aerobic and work activity of all athlete groups was higher (P < 0.01) than that of referents. Compared with the referents, both power and "mixed" athletes were more prone to eat fruits and vegetables and to avoid vitamin supplements, but less prone to use butter and high-fat milk, and to smoke (odds ratios different from 1.0, P < 0.05). Also endurance athletes smoked less and drank less alcohol than the referents (P < 0.05). Higher leisure aerobic activity and less frequent smoking after athletic years might explain higher life expectancy of Finnish athletes.

Adult↗
PubMed2003

Single muscle fiber myosin heavy chain distribution in elite female track athletes.

PURPOSE: Myosin heavy chain (MHC) characterization of tissue samples from the gastrocnemius muscle of six elite female athletes and 10 untrained females was performed using myosin ATPase histochemistry and gel electrophoresis. Athletes were of national and international caliber, whereas their untrained counterparts were healthy individuals not involved in a regular exercise program. METHODS: Muscle biopsies for the athletes were performed 14 wk into their training season and analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and myosin ATPase techniques. RESULTS: Electrophoretic analysis of single muscle fibers from elite athletes revealed a MHC phenotype composition of 46 +/- 6% type I, 21 +/- 6% type IIa, and 0% type IIx, whereas 34% of the single fibers expressed multiple MHC isoforms. When compared with the elite women, untrained subjects demonstrated higher percentages of type I MHC and lower percentages of IIa MHC muscle fibers, 57 +/- 5 and 16 +/- 3%, respectively (P < 0.05). Similar to the female athletes, 27% of the fibers from untrained women possessed multiple myosin isoforms. Myosin ATPase staining demonstrated a greater percentage of type I fibers in untrained subjects versus the elite women (67 +/- 3 vs 41 +/- 2%, P< 0.05) (mean +/- SE), whereas the athletes had a higher percentage of type IIa fibers compared with the untrained women (49 +/- 5 vs 19 +/- 2%, P< 0.05). There were no differences in the percentage of IIb fibers between elite and untrained women (11 +/- 4 vs 14 +/- 2%, respectively). CONCLUSIONS: Whereas a preponderance of hybrid fibers is generally observed in untrained populations, the diverse MHC phenotype seen in these elite female athletes is uncommon. These unique findings are attributed to the chronic and varied nature of training in which these athletes were involved.

Adult↗
PubMed2003

ACE I/D polymorphism and cardiac adaptations in adolescent athletes.

PURPOSE: The aim of this cross-sectional study was to determine whether there is a correlation between left ventricular hypertrophy (LVH) and angiotensin converting enzyme (ACE) insertion/deletion (I/D) polymorphism in adolescent athletes. METHODS: Seventy-five competitive soccer players (aged 15 +/- 1.2 yr) and 52 untrained control subjects (aged 15 +/- 1.6 yr) were examined with echocardiography (echo) and bioelectrical impedance analysis. The ACE genotype of all subjects was determined by PCR and correlated with left ventricular mass (LVM) indices. RESULTS: Allele frequencies were comparable between athletes and controls. Body surface area (BSA), fat-free mass (FFM), and all mean echo measurements were significantly greater in athletes than in controls. LVM and LVM indices for both BSA and FFM were all significantly greater in athletes than in controls (LVM 195.3 +/- 32 g vs 165.3 +/- 37.6 g; LVM/BSA 115.5 +/- 18.9 g x mq(-1) vs 95 +/- 18.2 g x mq(-1); LVM/FFM 3.5 +/- 0.5 vs 3 +/- 0.54, P < 0.001 for the three variables). Left ventricular hypertrophy was found in 17 (23%) athletes. There was no correlation between ACE I/D polymorphism and athletes with LVH as the II and DD genotype frequencies were identical (41%). However, in athletes with LVH, the presence of the D allele was associated with a greater LVM index than compared to homozygous II genotype (LVM = 145 +/- 7.6 g x mq(-1) in DD+ID group vs 135 +/- 2.9 g x mq(-1) in II group, P = 0.008). CONCLUSIONS: The results of the study show that significant changes occur in cardiac morphology and function in adolescent athletes. Interestingly, the ACE I/D polymorphism was associated with the degree of cardiac hypertrophy but not with the occurrence of LVH itself.

Adolescent↗
PubMed2004

Bone mineral density of olympic-level female winter sport athletes.

PURPOSE: To compare areal bone mineral density (aBMD) of female winter sport athletes to healthy controls of similar age and body mass index (BMI). METHODS: Areal BMD (g x cm(-2)) of the whole body, lumbar spine (L2-L4), and right proximal femur were assessed by dual energy x-ray absorptiometry in athletes (N = 40; age: 26.1 +/- 5.7 yr; ht: 165.6 +/- 0.1 cm; wt: 63.0 +/- 6.5 kg; BMI: 23.0 +/- 1.9 kg x m(-2)) involved in speed skating (N = 9), snowboarding (N = 13), freestyle skiing (N = 3), biathlon (N = 8), bobsleigh, skeleton, luge (N = 7), and controls (N = 21; age: 26.0 +/- 5.1 yr; ht: 165.8 +/- 0.1 cm; wt: 62.8 +/- 5.9 kg; BMI: 22.9 +/- 1.3 kg x m(-2)). RESULTS: Using independent t-tests, athletes had lower fat mass, percent body fat, and higher lean mass than controls (P < 0.001). Areal BMD was higher in athletes than controls for all skeletal sites (P </= 0.007). With lean tissue mass as a covariate (ANCOVA), differences in aBMD remained significant for most skeletal sites (P </= 0.016). Menstrual history, mean daily calcium intake, and oral contraceptive use were not associated with aBMD in the athletic group. CONCLUSION: Results show that female winter sport athletes have greater aBMD compared with controls of similar age and BMI. Most aBMD differences remained significant after adjusting for lean tissue mass, and athletes with a history of oligo- and/or amenorrhea had similar aBMD than their eumenorrheic counterparts. This is the first study to examine aBMD in winter sport athletes. The results support the hypothesis that the loading characteristics of intense winter sport participation have osteogenic potential.

Adult↗
PubMed2004

Field exercise vs laboratory eucapnic voluntary hyperventilation to identify airway hyperresponsiveness in elite cold weather athletes.

STUDY OBJECTIVE: For the 2002 Winter Olympic Games, athletes were required to submit objective evidence of asthma or exercise-induced bronchoconstriction (EIB) for approval to inhale a beta(2)-agonist. Eucapnic voluntary hyperventilation (EVH) was recommended as a laboratory challenge that would identify airway hyperresponsiveness (AHR) consistent with EIB. The objective was to compare the change in FEV(1) provoked by EVH with that provoked by exercise in cold weather athletes. DESIGN: Spirometry was measured before and for 15 min after challenges. The two challenges were performed in random order at least 24 h apart. SETTING: EVH was performed in the laboratory at 19 degrees C, and exercise took place in the field in the cold (2 degrees C, 45% relative humidity). PARTICIPANTS: Thirty-eight athletes (25 female subjects; median age, 16 years). INTERVENTIONS: For the EVH, athletes inhaled dry air containing 5% carbon dioxide for 6 min at a target ventilation equivalent to 30 times baseline FEV(1). Exercise was performed by cross-country skiing, ice skating, or running for 6 to 8 min. MEASUREMENTS AND RESULTS: AHR consistent with EIB was defined as >or= 10% fall in FEV(1) from baseline after challenge. Eleven athletes were exercise positive (EX+) [FEV(1) fall, 20.5 +/- 7.3%], and 17 athletes were EVH positive (FEV(1) fall, 14.5 +/- 4.5%) [mean +/- SD]. Of 19 subjects with AHR, 58% were identified by exercise and 89% were identified by EVH. EVH identified 9 of 11 subjects who were EX+ and a further 8 subjects with potential for EIB. The average ventilation during EVH was 28 times FEV(1). CONCLUSION: Performing EVH for 6 min in the laboratory had a greater chance of identifying AHR in these athletes compared with 6 to 8 min of field exercise in the cold. The EVH test will be useful to evaluate elite summer sports athletes whose widely different forms of exercise provide an "equipment" challenge to any laboratory.

Adolescent↗
PubMed2003

Relationship between change in BMI with age and delayed menarche in female athletes.

Body mass index (BMI) is widely used as an index of obesity in people from the school age children to adults. However, the relationship between the change in BMI with age and the coming of menarche has not been discussed as there are few reports on the changes in BMI with age. In this study, the change in BMI with age was examined by applying the wavelet interpolation method (WIM), and a critical period for body fat in terms of the coming of menarche was estimated from the growth velocity. We investigated delayed menarche according to the influence of stress in athletes by comparing delayed menarche between athletes and non-athletes in relation to the critical period. Data were obtained from 144 female athletes in their first year at university in the Tokai area, all of whom had competed in a national sports competition in high school (athlete group). Health examination records showing these subjects' heights and weights from the first grade of elementary school to the final year of high school (1984-1995) were collected and BMI was calculated for each grade. Ages at menarche were ascertained from questionnaires. A control group of 73 non-athletes was similarly examined. The age at maximum peak velocity (MPV) derived from the growth (aging) distance curve of BMI was determined in the control group to be 11.96+/-0.97 years old. This age at MPV of BMI was almost the same as the age at menarche (12.11+/-0.93 years old). Therefore, this age at MPV of BMI is estimated to be the critical period of body fat for the coming of menarche. The interval between the age at MPV of BMI and age at menarche was 0.74+/-1.30 years in the athlete group and 0.15+/-0.81 years in the control group, so there was a significant difference (P<0.01) between the two groups. It is suggested that the delayed menarche in athletes is influenced by the stress of regular sports training.

Adolescent↗
PubMed1988

Iron, zinc and magnesium nutrition and athletic performance.

During the last decade there has been considerable interest in the idea that dietary trace elements supplementation can result in an improvement in athletic performance. The current paper discusses this idea as it relates to 3 elements: iron, zinc and magnesium. Emphasis has been placed on examining the implicit assumptions underlying the idea that mineral supplements help the athlete. These assumptions include the beliefs that the athlete has a higher than normal requirement for minerals; that the athlete consumes a diet inadequate in these minerals; and that a marginal deficiency of these elements has a direct effect on athletic performance. Evidence is presented that both iron deficiency and magnesium deficiency can result in a significant reduction in exercise performance; however, the biochemical lesions underlying the reductions in exercise performance have not been identified. There is evidence that dietary magnesium intake may be suboptimal in some individuals, thus dietary supplementation of this element may be useful in some population groups. Excessive magnesium supplementation is not thought to be a serious health problem. Similar to magnesium dietary iron supplements can improve athletic performance in individuals severely deficient in this element. However, few studies have documented a need for iron supplements in healthy athletes. If iron supplements are used, it is important that the level of supplementation is not excessive, as excess iron in the diet can result in an induced zinc deficiency. In marked contrast to iron and magnesium, there is little evidence for the idea that zinc deficiency influences exercise performance in humans. Despite this fact, zinc supplements have been widely advocated for the athlete, as it is known that intense exercise can result in changes in zinc metabolism. If zinc supplements are used, it is important that they are not excessive, as excess zinc in the diet can result in a secondary copper deficiency.

Humans↗