Within-day energy deficiency and reproductive function in female endurance athletes

We aimed to estimate and compare within-day energy balance (WDEB) in athletes with eumenorrhea and menstrual dysfunction (MD) with similar 24-hour energy availability/energy balance (EA/EB). Furthermore, to investigate whether within-day energy deficiency is associated with resting metabolic rate (RMR), body composition, S-cortisol, estradiol, T₃ , and fasting blood glucose. We reanalyzed 7-day dietary intake and energy expenditure data in 25 elite endurance athletes with eumenorrhea (n = 10) and MD (n = 15) from a group of 45 subjects where those with disordered eating behaviors (n = 11), MD not related to low EA (n = 5), and low dietary record validity (n = 4) had been excluded. Besides gynecological examination and disordered eating evaluation, the protocol included RMR measurement; assessment of body composition by dual-energy X-ray absorptiometry, blood plasma analysis, and calculation of WDEB in 1-hour intervals. Subjects with MD spent more hours in a catabolic state compared to eumenorrheic athletes; WDEB < 0 kcal: 23.0 hour (20.8-23.4) vs 21.1 hour (4.7-22.3), P = .048; WDEB < -300 kcal: 21.8 hour (17.8-22.4) vs 17.6 hour (3.9-20.9), P = .043, although similar 24-hour EA: 35.6 (11.6) vs 41.3 (12.7) kcal/kg FFM/d, (P = .269), and EB: -659 (551) vs -313 (596) kcal/d, (P = .160). Hours with WDEB <0 kcal and <-300 kcal were inversely associated with RMR_ratio (r = -.487, P = .013, r = -.472, P = .018), and estradiol (r = -.433, P = .034, r = -.516, P = .009), and positively associated with cortisol (r = .442, P = .027, r = .463, P = .019). In conclusion, although similar 24-hour EA/EB, the reanalysis revealed that MD athletes spent more time in a catabolic state compared to eumenorrheic athletes. Within-day energy deficiency was associated with clinical markers of metabolic disturbances.

The effect of the hypohydration on the lactate threshold in a hot and humid environment

AIM

The purpose of this study was to investigate the effect of hypohydration (HH) on the lactate threshold (LT) in a hot and humid environment.

METHODS

Ten apparently healthy males (age 25+/-3 yrs; height 1.8+/-0.04 m; mass 78+/-12 kg; VO2peak 3.7+/-0.4 L/min) underwent four randomly assigned maximal treadmill tests. Two trials were at room temperature (22+/-1 degrees C; RH = 50%) under two different hydration conditions: euhydrated (EH-RM) and hypohydrated (HH-RM), and two trials were performed in a warm chamber (37+/-0.5 degrees C; RH = 70%) under two different hydration conditions: euhydrated (EH-HT) and hypohydrated (HH-HT). The desired HH level (2-4%) was accomplished in the 24+ hours before testing by fluid restriction. Mean HH was 2.6+/-1.0% body weight. Capillary blood samples were collected at the end of each stage and analyzed for lactic acid (LA). LA concentrations were plotted for each exercise stage, and the LT was determined by visual inspection as the highest exercise stage at which blood LA concentration began to increase above each individual's resting levels. LT and body temperature were analyzed with a two-way repeated measures ANOVA (P < 0.05).

RESULTS

During the trials in the warm chamber, the LT occurred at a significantly earlier stage compared to the thermoneutral environment (4.4+/-0.09 vs 5.8+/-0.10) and with a significantly lower oxygen consumption (2.38+/-0.09 L.min(-1) vs 2.86+/-0.13 L.min(-1)). Body temperature at the LT was significantly higher in the heat trials compared to room temperature (38.7+/-0.12 degrees C vs 37.6+/-0.14 degrees C). LT determination was not significantly altered by hydration.

CONCLUSION

These results suggest that during progressive incremental maximal treadmill exercise, moderate HH does not affect the LT, whereas exercise in a hot and humid environment induces a downward shift in the LT. The elevated body temperature during the heat trials suggests that body temperature may affect running performance associated with the LT.

Height velocity and skeletal maturation in elite female rhythmic gymnasts

Rhythmic gymnasts performing under conditions of high intensity are exposed to particularly high levels of psychological stress and intense physical training, factors that can contribute to the observed delay in skeletal maturation and pubertal development, and alter optimal growth. The study was conducted in the field, during the International, European, and World Rhythmic Sports Gymnastics Championships of the years 1997-2000, and included 104 elite female rhythmic gymnasts, aged 12-23 yr. The study included height and weight measurements, estimation of body fat and skeletal maturation, and registration of parental height. Height, weight, target height, and predicted adult height were expressed as the SD score of the mean height and weight for age, according to Tanner's standards. Gymnasts were taller and thinner than average for age, with height velocity SD score for each age group above the 50th percentile for all age groups (n = 140, mean = 1.9 +/- 2.5). Interestingly, although height velocity in normal girls comes to an end by the age of 15, in our examined rhythmic gymnasts it continues up to the age of 18. There was a delay of skeletal maturation of 1.8 yr (n = 72, r = 0.730, P < 0.001), compensated by an acceleration of height velocity toward the end of puberty. The final adult height was identical to the estimated predicted height at first evaluation, and significantly higher than the genetically determined target height (n = 35, r = 0.58, P < 0.001), denoting that genetic predisposition to final height is not only achieved, but even exceeded. Using multiple regression analysis, target height was the only independent parameter that has been proven to influence positively the height velocity SD score (b = 0.233, t = 2.215, P = 0.029), denoting that genetic predisposition remains the main driving force for the observed efficient catch up growth. In conclusion, the elite rhythmic gymnasts compensate for their loss of pubertal growth spurt by a late acceleration of linear growth. Despite the delay in skeletal maturation, genetic predisposition of growth is not only preserved, but even exceeded.

Assessment of under-reporting of energy intake by elite female gymnast

This study examines the degree of under-reporting of energy intake by elite, female gymnasts, and the impact this predicted under-reporting has on associated macro and micro nutrient intake. Twenty-eight female U.S. national team artistic gymnasts participated in the study. Dietary intake was assessed using 3-day food records, and the degree of under-reporting was predicted from the ratio of reported energy intake (EI) to predicted basal metabolic rate (BMRestd), using the standards described by Goldberg et al. (10). Sixty-one percent of the subjects had an EI/BMRestd ratio of < 1.44, and were classified as under-reporters. The under-reporters had higher BMIs and percent body fat, and lower reported total energy intakes than the adequate energy reporters. Additionally, under-reporting of energy intake had a significant impact on reported micro nutrient intake. The under-reporting of energy intake seen in these subjects has an impact on the reported intake of macro and micro nutrients that can influence the interpretation of the nutritional status of these athletes and the strategy for nutrition intervention. Therefore, when assessing dietary intakes of elite gymnasts, some means of determining the accuracy of the reported energy and nutrient intake should be employed to more accurately identify the true nutritional problems experienced by these elite athletes.

Relationship between energy deficits and body composition in elite female gymnasts and runners

PURPOSE

The purpose of this study was to evaluate energy balance and body composition in 42 gymnasts (mean age = 15.5 yr) and 20 runners (mean age = 26.6 yr), all of whom were on national teams or were nationally ranked.

METHODS

Athletes were assessed for body composition using DEXA and skinfolds, and energy balance was determined with a Computerized Time-Line Energy Analysis (CTLEA) procedure.

RESULTS

Results from the CTLEA were assessed as the number of within-day energy deficits (largest and frequency) and within-day energy surpluses (largest and frequency). There was a significant difference (P = 0.000) in the mean number of hourly energy deficits > 300 kcal experienced by gymnasts (9.45 +/- 6.00) and runners (3.70 +/- 5.34). There was also a significant difference (P = 0.001) in the mean number of hourly energy surpluses > 300 kcal experienced by gymnasts (1.40 +/- 3.04) and runners (6.20 +/- 5.50). The mean largest daily energy deficit was 743 (+/- 392) kcal for gymnasts and 435 (+/- 340) kcal for runners. The mean largest daily energy surplus was 239 (+/- 219) kcal for gymnasts, and 536 (+/- 340) kcal for runners. There was a significant relationship between the number of daily energy deficits > 300 kcal and DEXA-derived body fat percent for gymnasts (r = 0.508; P = 0.001) and for runners (r = 0.461; P = 0.041). There was also a negative relationship between the largest daily energy surplus and DEXA-derived body fat percentage for gymnasts (r = -0.418; P = 0.003). Using the energy balance variables, age, and athlete type (artistic gymnast, rhythmic gymnast, middle-distance runner, long-distance runner) as independent variables in a forward stepwise regression analysis, a small but significant amount of variance was explained in DEXA-derived (P = 0.000; R2 = 0.309) and skinfold-derived (P = 0.000; R2 = 0.298) body fat percent by the number of energy deficits > 300 kcal and age.

CONCLUSIONS

These data suggest that within-day energy deficits (measured by frequency and/or magnitude of deficit) are associated with higher body fat percentage in both anaerobic and aerobic elite athletes, possibly from an adaptive reduction in the REE. These data should discourage athletes from following restrained or delayed eating patterns to achieve a desired body composition.

Working with young athletes: views of a nutritionist on the sports medicine team

Athletes are influenced by coaches, other athletes, media, parents, the national sport governing body, members of the sports medicine team, and the athlete's own desire for success. It is impossible, therefore, for one member of the sports medicine team to unilaterally determine workable solutions that enhance performance and diminish health problems in an athlete. A focus on ensuring that the athlete can perform to the best of her ability is a key to encouraging discussion between the nutritionist, athlete, and coach. Using the assumption that health and top athletic performance are compatible, this focus on performance provides a discussion point that all parties can agree to and, if approached properly, also fulfills the nutritionist's goal of achieving optimal nutritional status. Membership on the sports medicine team mandates that the nutritionist know the paradigms and health risks associated with the sport and develop assessment and feedback procedures specific to the athlete's needs.

Exercise intensity does not effect body composition change in untrained, moderately overfat women

OBJECTIVE

To determine whether exercise intensity effects a change in body composition.

DESIGN/SUBJECTS

Twelve untrained, moderately overfat, weight-stable women were randomly assigned to a high-intensity (80% VO2max) or low-intensity (50% VO2max) exercise group. Subjects trained four times per week for 12 weeks in monitored sessions, with a duration sufficient to expend 300 kcal. During this time, subjects were instructed to maintain their normal diet and activity patterns.

OUTCOME MEASURES

Pretesting and posttesting included measurement of height, weight, body fat (via hydrostatic weighing), seven skinfold sites, seven circumference sites, and VO2max.

STATISTICAL ANALYSES

Results were analyzed using the Student's t test and paired samples t test.

RESULTS

Posttesting revealed no significant between-group differences for change in weight, percent body fat, fat mass, fat-free mass, sum of skinfold measurements, or sum of circumference measurements. Mean weight loss was 0.7 lb for the high-intensity group (P = .55) and 3.3 lb for the low-intensity group (P = .03). Hydrostatic data revealed that each group lost an identical amount of fat (5.0 lb), but the high-intensity group gained more than twice as much fat-free mass (4.3 vs 1.8 lb). The greater increase in fat-free mass by the high-intensity group explains why the low-intensity group had a greater absolute weight loss.

APPLICATIONS/CONCLUSIONS

This study suggests that fat loss is a function of energy expended rather than exercise intensity. Therefore, if fat loss is the goal and time is limited, persons should exercise safely at as high an intensity as tolerable to expend as much energy as possible during their allotted time.

Selected body composition and growth measures of junior elite gymnasts

Selected body composition measures of female junior elite gymnasts (n = 146) were evaluated cross-sectionally (ie, we observed a younger and an older group at one point in time, not the same individuals over time). For certain comparisons, the gymnasts were grouped into a younger group (7- to 10-year-olds) and an older group (11- to 14-year-olds). Gymnasts were in the 50th percentile for weight:height ratio, regardless of age. However, weight:age and height:age percentiles progressively dropped from the 48th to the 20th as age increased. Body fat percentage did not differ significantly between age groups. Triceps and subscapular skinfolds were 63% and 56%, respectively, of the age-related standard for the younger group and 52% and 39%, respectively, of the age-related standard for the older group. Arm muscle circumference and calculated arm muscle area of the gymnasts were in about the 75th percentile, regardless of age grouping. In general, as they grew older, gymnasts became progressively smaller in weight and height for age but were highly muscled for size. The steady age-related drop in height:age and weight:age percentile may be attributable to nutritional deficits, a sport-specific selection favoring retention of small but powerful gymnasts, or a combination of these factors. We recommend that young gymnasts be carefully observed longitudinally by trained nutrition professionals to ensure that inadequate nutrient intake is not a contributing factor to poor growth or health.