Female Endurance Runners Research Articles

Setting, Age, & Intensity Influence Psychological and Physiological Processes in Young Female Endurance Runners

Setting, Age, & Intensity Influence Psychological and Physiological Processes in Young Female Endurance Runners

Posters

Objectives: The purpose of this study was to assess the impact of an anti-gravity treadmill return to running programme on self-efficacy and subjective knee function following knee osteochondral surgery. Methods: Two otherwise healthy female endurance runners who had undergone knee osteochondral surgery were recruited. Patient A was 9 months post-surgery for a left knee femoral cartilage grade 3–4 defect 3 cm2. Patient B was 11 weeks post-surgery for a partial lateral menisectomy and chondroplasty. An anti-gravity treadmill was usedto manipulate loading during a graduated phased return to running. Self-efficacy was evaluated using the Self-Efficacy for Rehabilitation outcomes scale (SER) and the Knee Self-Efficacy Scale (K-SES). Subjective knee function was evaluated using the Knee injury and Osteoarthritis Outcome Score (KOOS). Results: The programmes resulted in improvements in SER (Patient A 57%; Patient B 18%) and K-SES present (Patient A 89%; Patient B 33%) and K-SES future (Patient A 65%; Patient B 33%). Only the KOOS Sport/Rec (Patient A and B) and the Quality of Life (Patient B) subscales showed clinically important improvements. Conclusions: The programmes resulted in improved knee and rehabilitation self-efficacy and subjective knee function following osteochondral repair of the knee. These case reports illustrate the importance of considering self-efficacy in individualising rehabilitation after knee osteochondral surgery and highlights the potential role for anti-gravity treadmills in enhancing self-efficacy and subjective knee function in preparation for a return to sport.

The Effect of Ongoing Vitamin D and Low-Fat Milk Intake on Bone Metabolism in Female High-School Endurance Runners.

BackgroundVitamin D and calcium are essential nutrients for bone health. In addition, vitamin D suppresses inflammatory cytokines and increases bone resorption. Therefore, improvements in bone health by calcium and vitamin D supplementation have the potential to not only improve calcium metabolism but also suppress inflammation associated with exercise training. The purpose of this study was to determine whether ongoing vitamin D supplementation and low-fat milk intake by female high-school endurance runners would improve bone metabolism by suppressing inflammatory cytokines and the parathyroid hormone (PTH).MethodsTwenty female high-school runners were assigned to a vitamin D supplement and low-fat milk intake group (MKD) or a control group (CON). Participants in the MKD group consumed a vitamin D supplement (1,000 IU/day) and low-fat milk (Ca 315 mg/day) for 6 months. Bone mineral density measurements, blood samples, and questionnaires (regarding menses and diet) were carried out. The UMIN Clinical Trials Registry number is UMIN000027854.ResultsThe 25-hydroxyvitamin D (25(OH)D) concentration in MKD was sustained and PTH concentration was decreased regardless of the state of menses. The correlation coefficients of 25(OH)D or PTH concentrations and bone metabolism markers were analyzed by partial correlation coefficient via adjusting the model for frequency of menses. CTX and 25(OH)D concentration were significantly and inversely correlated at baseline (r = -0.61, P < 0.01), 3 months (r = -0.54, P = 0.02), and 6 months (r = -0.53, P = 0.02). CTX and PTH were significantly and positively correlated at 3 months (r = 0.63, P < 0.01) and 6 months (r = 0.52, P = 0.02). The bone alkaline phosphatase (BAP)/CTX ratio and 25(OH)D concentration were significantly and positively correlated at 3 months (r = 0.59, P = 0.01) and 6 months (r = 0.56, P = 0.01). The BAP/CTX ratio and PTH were significantly and inversely correlated at 3 months (r = -0.59, P = 0.01) and 6 months (r = -0.58, P < 0.01).ConclusionsThis study suggested that vitamin D and low-fat milk supplementation improves bone metabolism by sustaining the 25(OH)D concentration and decreasing the PTH concentration in female high-school endurance runners regardless of the state of menses.

Thyroid hormones and commonly cited symptoms of overtraining in collegiate female endurance runners

Overtraining syndrome (OTS) is reported in endurance sports. Thyroid hormones (TH) regulate metabolism, mood, and energy production, and may play a role in OTS of endurance athletes. The purpose of this study was to investigate relationships in TH and symptoms of OTS in track and field endurance runners (ER). Sixteen female track and field middle distance (MD; n = 9; age: 20.2 ± 1.5years; ht: 167.86 ± 5.04cm; body-mass: 57.97 ± 5.05kg; VO2MAX: 53.62 ± 6.04ml/kg/min) and long distance (LD; n = 7; age: 20.5 ± 1.5years; ht: 162.48 ± 6.11cm; body-mass: 56.15 ± 5.99kg; VO2MAX: 61.94 ± 3.29ml/kg/min) ER participated in this descriptive study (15-weeks). Thyroid-stimulating hormone (TSH), triiodothyronine (T 3), and thyroxine (T 4), were collected at pre-(PRE) and post-season (POST). A fatigue scale was administered weekly, and percent change (PΔ) in race time (season best vs. championship performance) was calculated. Wilcoxon-sign ranked tests and Spearman's rho correlations were used to determine changes and relationships between TH and performance. TSH, T 3 and T 4 did not change from PRE to POST. The percent change (PΔ) in T 3 from PRE to POST was correlated with running performance at the end of the season (ρ = - 0.70, p = 0.036). Fatigue at week 12 correlated with running performance at the end of the season (ρ = -0.74, p = 0.004). TH may be valuable in assessing the overall training state of ER. TH concentrations change too slowly to be a frequent marker of monitoring OTS, but are related to markers of decreased performance. Monitoring dietary intake, and fatigue may be predictive markers to assess OTS and training status of female ER.

Effect of protein and carbohydrate solutions on running performance and cognitive function in female recreational runners.

This study compared the effects of a carbohydrate–electrolyte–protein solution (CEPS, 2% protein plus 4% carbohydrate), carbohydrate–electrolyte solution (CES, 6% carbohydrate), and noncaloric sweetened placebo (PLA) on both 21-km running performance and cognitive function. Eleven female recreational endurance runners performed a 21-km time-trial running on three occasions, separated by at least 28 days. In a randomized cross-over design, they ingested CEPS, CES, or PLA at a rate of 150 mL every 2.5 km with no time feedback. A cognitive function test was performed before and after the run. Participants ingested approximately 24 g/h carbohydrate plus 12 g/h protein in CEPS trial, and 36 g/h carbohydrate in CES trial during each 21-km trial. Time to complete the time-trial was slightly shorter (P < 0.05) during CES (129.6 ± 8.8 min) than PLA (134.6 ± 11.5 min), with no differences between CEPS and the other two trials. The CEPS trial showed higher composite of visual motor speed than the PLA trial (P < 0.05). In conclusion, CES feedings might improve 21-km time-trial performance in female recreational runners compared with a PLA. However, adding protein to the CES provided no additional time-trial performance benefit. CEPS feeding during prolonged exercise could benefit visual motor speed compared to PLA alone, but no differences in the performance of the other cognitive function tests were found.

Carbohydrate mouth rinse does not affect performance during a 60-min running race in women

ABSTRACTThis study examined the effect of carbohydrate mouth rinsing on endurance running performance in women. Fifteen female recreational endurance runners, who used no oral contraceptives, ran two races of 1-h duration on an indoor track (216-m length) at 18:00 h after an 8-h fast with a 7-days interval between races, corresponding to the 3rd-10th day of each premenopausal runner’s menstrual cycle, or any day for the postmenopausal runners. In a double-blind random order, participants rinsed their mouth with 25 ml of either a 6.4% carbohydrate (RCHO) or a placebo solution (RP). No fluid was ingested during exercise. Serum 17β-Εstradiol (P = 0.59) and Progesterone (P = 0.35) did not differ between treatments. There was no difference in 1-hour running performance (RCHO: 10,621.88 ± 205.98 m vs. RP: 10,454.00 ± 206.64 m; t = 1.784, P = 0.096). Furthermore, the mean percentage effect (±99%CI) of RCHO relative to RP, 1.67% (−1.1% to 4.4%), and Cohen’s effect size (d = 0.21) support a trivial outcome of RCHO for total distance covered. In conclusion, carbohydrate mouth rinsing did not improve 60-min track running performance in female recreational runners competing in a low ovarian hormone condition, after an 8-h fast and when no fluid was ingested during exercise.

Carbohydrate Mouth Rinse Does Not Affect 60-min Running Performance In Females

Mouth rinsing with carbohydrate may improve 60-min endurance cycling or running performance in males. However, no data exist regarding the effect of mouth rinsing on endurance performance in females. PURPOSE: To examine the effect of mouth rinsing with a carbohydrate solution on endurance running performance in females. METHODS: Fifteen female recreational endurance runners (30-57 years) ran 2 races of 1-hour duration on an indoor track after an 8 h post-prandial period with a 7 days interval between races. This time period corresponded to the 3rd-10th day of each runner’s menstrual cycle, for the eumenorrhoeic premenopausal runners, or any time for the runners who were at menopause. Following a double-blind process and random order, participants rinsed their mouth, before the initiation of exercise and at 15, 30 and 45 min of exercise with 25 ml of either a 6.4% carbohydrate (RCHO) or a placebo solution (0% carbohydrate) (RP). Pre-race euhydration was insured by ingestion of 6 ml·kg-1 water. No fluids were ingested during exercise. Races started at 18:00 hours. RESULTS: There was no difference between treatments in runners hormonal status prior to each race for serum 17β-Estradiol [median (inter-quartile range)], RCHO: 50.2(5; 74.1) pg[BULLET OPERATOR]ml-1 vs RP: 26.0(5; 61.1) pg[BULLET OPERATOR]ml-1, z= -0.533, (p= 0.59) and Progesterone (RCHO: 0.75(0.61; 1.64) ng[BULLET OPERATOR]ml-1 vs RP: 0.74(0.64; 0.9) ng[BULLET OPERATOR]ml-1, z= -0.938, (p= 0.35). Percent body mass loss due to exercise was similar between treatments (mean ± SE, RCHO: 1.9% ± 0.1% and RP: 1.9% ± 0.1%). There was no difference in 1-hour running performance, neither by treatment (RCHO: 10621.88 ± 205.98 m vs. RP: 10454.00 ± 206.64 m; t= 1.784, p= 0.096), nor by race order (1st race: 10549.13 ± 213.67 m vs. 2nd race 10526.75 ± 201.16 m; t= 0.215, p= 0.833) (mean ± SE). Furthermore, the mean percentage effect (±99%CI) of RCHO relative to RP, 1.67%(-1.1% to 4.4%), and Cohen’s effect size (d = 0.21) support a trivial outcome effect of RCHO for total distance covered. In addition, there was no difference between treatments in the rate of perceived exertion (p= 0.14) and heart rate (p= 0.06). CONCLUSION: Carbohydrate mouth rinsing did not improve 1-h running performance in female recreational runners competing in a low ovarian hormone condition, following an 8 h fast and when no fluid was ingested during exercise.

Comparison of Site-Specific Bone Mineral Densities between Endurance Runners and Sprinters in Adolescent Women.

We aimed to compare site-specific bone mineral densities (BMDs) between adolescent endurance runners and sprinters and examine the relationship of fat-free mass (FFM) and nutrient intake on BMD. In this cross-sectional study, 37 adolescent female endurance runners and sprinters (16.1 ± 0.8 years) were recruited. BMD and FFM were assessed by dual-energy X-ray absorptiometry. Nutrient intake and menstrual state were evaluated by questionnaires. After adjusting for covariates, spine and total bone less head (TBLH) BMDs were significantly higher in sprinters than endurance runners (TBLH, 1.02 ± 0.05 vs. 0.98 ± 0.06 g/cm2; spine, 0.99 ± 0.06 vs. 0.94 ± 0.06 g/cm2; p < 0.05). There was no significant difference between groups in other sites. The rate of menstrual abnormality was higher in endurance runners compared with sprinters (56.3% vs. 23.8%; p < 0.05). FFM was a significant covariate for BMD on all sites except the spine (p < 0.05). Dietary intake of vitamin D was identified as a significant covariate only for pelvic BMD (p < 0.05). The BMDs of different sites among endurance runners and sprinters were strongly related to FFM. However, the association of FFM with spine BMD cannot be explained by FFM alone. Other factors, including nutrition and/or mechanical loading, may affect the spine BMD.

The Supplementation of Branched-Chain Amino Acids, Arginine, and Citrulline Improves Endurance Exercise Performance in Two Consecutive Days.

The central nervous system plays a crucial role in fatigue during endurance exercise. Branched-chain amino acids (BCAA) could reduce cerebral serotonin synthesis by competing with its precursor tryptophan for crossing the blood brain barrier. Arginine and citrulline could prevent excess hyperammonemia accompanied by BCAA supplementation. This study investigated the combination of BCAA, arginine, and citrulline on endurance performance in two consecutive days. Seven male and three female endurance runners ingested 0.17 g·kg-1 BCAA, 0.05 g·kg-1 arginine and 0.05 g·kg-1 citrulline (AA trial) or placebo (PL trial) in a randomized cross-over design. Each trial contained a 5000 m time trial on the first day, and a 10000 m time trial on the second day. The AA trial had significantly better performance in 5000 m (AA: 1065.7 ± 33.9 s; PL: 1100.5 ± 40.4 s) and 10000 m (AA: 2292.0 ± 211.3 s; PL: 2375.6 ± 244.2 s). The two trials reported similar ratings of perceived exertion. After exercise, the AA trial had significantly lower tryptophan/BCAA ratio, similar NH3, and significantly higher urea concentrations. In conclusion, the supplementation could enhance time-trial performance in two consecutive days in endurance runners, possibly through the inhibition of cerebral serotonin synthesis by BCAA and the prevention of excess hyperammonemia by increased urea genesis.

Biomechanics of running with rocker shoes.

Load reduction is an important consideration in conservative management of tendon overuse injuries such as Achilles tendinopathy. Previous research has shown that the use of rocker shoes can reduce the positive ankle power and plantar flexion moment which might help in unloading the Achilles tendon. Despite this promising implication of rocker shoes, the effects on hip and knee biomechanics remain unclear. Moreover, the effect of wearing rocker shoes on different running strike types is unexplored. The aim of this study was to investigate biomechanics of the ankle, knee and hip joints and the role of strike type on these outcomes. Randomized cross-over study. In this study, 16 female endurance runners underwent three-dimensional gait analysis wearing rocker shoes and standard shoes. We examined work, moments, and angles of the ankle, knee and hip during the stance phase of running. In comparison with standard shoes, running with rocker shoes significantly (p<0.001) reduced the positive (16%), and negative (32%) work at the ankle joint. Plantar flexion moment peak and impulse were also reduced by 11% and 12%, respectively. Reduction in these variables was almost two times larger for midfoot strikers than for rearfoot strikers. At the knee joint running with rocker shoes significantly increased the positive work (14%), extension moment peak (6%), and extension moment impulse (12%). These findings indicate that although running with rocker shoes might lower mechanical load on the Achilles tendon, it could increase the risk of overuse injuries of the knee joint.

Recommendations for Healthy Nutrition in Female Endurance Runners: An Update.

The purpose of this review is to present the basic principles of a healthy nutrition in female endurance runner enriched by the latest scientific recommendations. Female endurance runners are a specific population of athletes who need to take specifically care of daily nutrition due to the high load of training and the necessity to keep a rather low body mass. This paradoxical situation can create some nutritional imbalances and deficiencies. Female endurance athletes should pay attention to their total energy intake, which is often lower than their energy requirement. The minimal energy requirement has been set to 45 kcal/kg fat free mass/day plus the amount of energy needed for physical activity. The usual recommended amount of 1.2–1.4 g protein/kg/day has recently been questioned by new findings suggesting that 1.6 g/kg/day would be more appropriate for female athletes. Although a bit less sensitive to carbohydrate loading than their male counterparts, female athletes can benefit from this nutritional strategy before a race if the amount of carbohydrates reaches 8 g/kg/day and if their daily total energy intake is sufficient. A poor iron status is a common issue in female endurance runners but iron-enriched food as well as iron supplementation may help to counterbalance this poor status. Finally, they should also be aware that they may be at risk for low calcium and vitamin D levels.

Does Carbohydrate Augment the Beneficial Effects of Caffeine on 5 Kilometer Track Running Performance When Compared to Caffeine Alone in Female Endurance Runners?

Does Carbohydrate Augment the Beneficial Effects of Caffeine on 5 Kilometer Track Running Performance When Compared to Caffeine Alone in Female Endurance Runners?

Physiological Parameters for the Prediction of 5k Performance for Female Endurance Runners

Physiological Parameters for the Prediction of 5k Performance for Female Endurance Runners

PGC-related gene variants and elite endurance athletic status in a Chinese cohort: a functional study.

This study aims to examine the association between proliferator-activated receptor γ (PGC)-gene family-related single nucleotide polymorphisms (SNPs) and elite endurance runners' status in a Chinese cohort, and to gain insights into the functionality of a subset of SNPs. Genotype distributions of 133 SNPs in PPARGC1A, PPARGC1B, PPRC1, TFAM, TFB1M, TFB2M, NRF1, GABPA, GABPB1, ERRα, and SIRT1 genes were compared between 235 elite Chinese (Han) endurance runners (127 women) and 504 healthy non-athletic controls (237 women). Luciferase gene reporter activity was determined in 20 SNPs. After adjusting for multiple comparisons (in which threshold P-value was set at 0.00041), no significant differences were found in allele/genotype frequencies between athletes and controls (when both sexes were analyzed either together or separately). The lowest P-value was found in PPARGC1A rs4697425 (P = 0.001 for the comparison of allele frequencies between elite female endurance runners and their gender-matched controls). However, no association (all P > 0.05) was observed for this SNP in a replication cohort from Poland (194 endurance athletes and 190 controls). Using functional genomics tool, the following SNPs were found to have functional significance: PPARGC1A rs6821591, rs12650562, rs12374310, rs4697425, rs13113110, and rs4452416; PPARGC1B rs251466 and rs17110586; and PPRC1 rs17114388 (all P < 0.001). This study found no significant association between PGC-related SNPs and elite endurance athlete status in the Chinese population, despite some SNPs showing potential functional significance and the strong biological rationale to hypothesize that this gene pathway is a candidate to influence endurance exercise capacity.

Effects of an Individualized and Time Based Training Program on Physical Fitness and Mood States in Recreational Endurance Runners

Previous studies have shown that training guided individually by heart rate variability (HRV) elicits benefits on endurance performance. Meanwhile complex programs, which use HRV assessments to tailor exercise prescriptions to individual needs, are included in portable training computers. However, knowledge on health and fitness benefits of such training programs is still limited. Therefore, the aim of the present study was to investigate effects of HRV-based training included in a portable training computer vs general time-based training on aerobic fitness, half-marathon time as well as mood and mental states. Male (n=10) and female endurance runners (n=10) were recruited and randomly assigned to HRV-based (STAR) and predefined time-based training (TBT). At baseline and after 16 weeks of training an incremental exercise test with spirometry was performed to assess aerobic power. Additionally, mood and mental states were asked. After the training period all subjects took part in a half-marathon. Matched-pairs were selected to compare groups based on similar relative weekly energy expenditure during training. With no differences between groups, STAR and TBT reduced weight (p=0.029), body fat (p=0.002) as well as systolic and diastolic blood pressure (p≤0.001). Maximal oxygen uptake significantly increased from 43.0 ± 8.3 to 46.1 ± 9.0 ml.min-1.kg-1 (p≤0.001) and 43.2 ± 4.8 to 46.7 ± 4.7 ml.min-1.kg-1 (p≤0.001) in STAR and TBT, respectively. Moreover, both groups improved maximal velocity (TBT: 0.81 + 0.40 km.h-1 vs STAR: 0.74 + 0.39 km.h-1; p≤0.001) and completed the half-marathon with similar finish times (01:54:35 ± 00:14:02 [hh:mm:ss] vs. 01:52:42 ± 00:13:45 [hh:mm:ss]; p=0.789). Regarding mood and mental states, no major changes were observed over the training period. In conclusion, both HRV- and time-based training elicited similar improvements in aerobic power and body composition. Consequently, HRV-dependent exercise prescriptions serve as a practical tool for day-to-day periodization of aerobic exercise.

Sexual dimorphism of femoral neck cross-sectional bone geometry in athletes and non-athletes: a hip structural analysis study

The characterisation of bone geometry in male and female athletes may increase our understanding of how physical loading may enhance bone strength in both sexes. This study investigated sexual dimorphism in hip geometry of athletes and age- and sex-matched non-athletes. Dual energy X-ray absorptiometry of the left proximal femur was performed in 62 male (n = 31; 30.2 ± 4.6 years) and female (n = 31; 27.9 ± 5.2 years) competitive endurance runners, and 36 male (n = 18; 28.7 ± 5.8 years) and female (n = 18; 29.1 ± 5.3 years) non-athletes. The hip structural analysis programme determined areal bone mineral density (aBMD), bone area (BA), hip axis length, cross-sectional area (CSA), and cross-sectional moment of inertia (CSMI) of the femoral neck. Strength indices were derived from the femoral strength index (FSI) (Yoshikawa et al., J Bone Miner Res 9:1053-1064, 1994). Despite similar size-adjusted aBMD, sexual dimorphism was apparent for BA, CSA and CSMI, with superior values in men compared to women (P < 0.01). FSI was greater in male and female athletes than non-athletes (P < 0.01). From all groups, results in male athletes inferred greatest resistance to axial (CSA) and bending loads (FSI). Estimates of bone strength (FSI) were greater in female athletes than male and female non-athletes, supporting the osteogenic value of regular loading of the hip.

Altitude Training May Improve Subsequent Endurance Performance In Elite Runners

Native lowlanders sojourn to altitude as many coaches and athletes believe there may be a benefit for subsequent sea level performance. The scientific literature generally corroborates the anecdotal evidence with a mean (± SD) improvement in endurance performance of 1.9 ± 2.4% and 1.6 ± 1.8% reported (Bonetti & Hopkins, Sports Medicine 39, 2009) when using a live-high train-high approach and a live-high train-low approach, respectively. PURPOSE: To evaluate whether a three week training period at moderate altitude improves the frequency and margin of personal best performances over an entire track and field season (typically May-September) in elite endurance runners. METHODS: Fourteen male (n=8) and female (n=6) elite endurance runners (800m-10,000m event groups) undertook a four week altitude training period prior to the 2010 track season. Athletes slept at 1850m and trained for the majority of their sessions at 1800-2000m, except for 2 sessions per week at a lower altitude (1537m). A retrospective analysis was undertaken of race performances for the track and field seasons 2008-2010. The number of personal best performances for each season was collated and a one-way ANOVA was used to determine if there were differences between seasons. When differences were identified using the simple main effects analysis, seasons were examined using paired-sample t-tests. RESULTS: 24 personal best performances were recorded in 2010 which was greater than the number of personal best performances recorded in 2008 (15: p=0.010) and 2009 (16: p=0.018). The overall improvement in performance was 0.8%, 0.9% and 1.4% in 2008, 2009 and 2010, respectively. CONCLUSIONS: Four weeks living and training at moderate altitude prior to the track and field season resulted in more personal best performances compared to the previous two years in a group of 14 elite endurance runners (equating to an improvement in performance of 1.4%). A limitation of the present investigation was that training load was not controlled, but given that the present athletes were highly trained, it may be expected that the rate of progression would be similar or gradually smaller for each subsequent year. This study therefore suggests that a four week training period at altitude may be beneficial for subsequent endurance running performance.

Bone-Mineral Density and Other Features of the Female Athlete Triad in Elite Endurance Runners: A Longitudinal and Cross-Sectional Observational Study

Low bone-mineral density (BMD) is associated with menstrual dysfunction and negative energy balance in the female athlete triad. This study determines BMD in elite female endurance runners and the associations between BMD, menstrual status, disordered eating, and training volume. Forty-four elite endurance runners participated in the cross-sectional study, and 7 provided longitudinal data. Low BMD was noted in 34.2% of the athletes at the lumbar spine, and osteoporosis in 33% at the radius. In cross-sectional analysis, there were no significant relationships between BMD and the possible associations. Menstrual dysfunction, disordered eating, and low BMD were coexistent in 15.9% of athletes. Longitudinal analysis identified a positive association between the BMD reduction at the lumbar spine and training volume (p=.026). This study confirms the presence of aspects of the female athlete triad in elite female endurance athletes and notes a substantial prevalence of low BMD and osteoporosis. Normal menstrual status was not significantly associated with normal BMD, and it is the authors' practice that all elite female endurance athletes undergo dual-X-ray absorptiometry screening. The association between increased training volume, trend for menstrual dysfunction, and increased loss of lumbar BMD may support the concept that negative energy balance contributes to bone loss in athletes.

Cross-sectional evidence of suppressed bone mineral accrual among female adolescent runners

We aimed to evaluate patterns of bone mineral accrual among a cross-sectional sample of female adolescent runners and girls participating in a nonendurance running sport. One-hundred and eighty-three interscholastic competitive female athletes (age 16.0 +/- 0.1 years), 93 endurance runners and 90 nonrunners, completed a menstrual and sports history questionnaire, had their height and weight measured, and underwent a dual-energy X-ray absorptiometry scan for the measurements of body composition and bone mass. For the majority of analyses, the girls were separated into four groups according to their age (13 to 14 years, 15 years, 16 years, and 17 to 18 years). Runners' height, weight, body mass index (BMI), percent body fat, lean tissue mass, number of menstrual cycles in the past year, and months of participation in a non-lean-build/variable-impact-loading sport were significantly lower than mean values for nonrunners. Although bone mass rose at all sites in the nonrunners between the ages of 13 to 14 years and 17 to 18 years, no such increase was noted in the runners. Runners compared with nonrunners exhibited significantly lower body weight and height-adjusted total body and lumbar spine bone mineral content (BMC) values and lower bone mineral density (BMD) Z-score values among the older (16 years and/or 17 to 18 years) but not younger (13 to 14 years and/or 15 years) age groups. These findings suggest that the runners, in contrast to the nonrunners, exhibited a suppressed bone mineral accrual pattern, which supports the notion that female adolescent endurance runners may be at risk for inadequate bone mass gains and thus a low peak BMD.

Insufficient Energy Intake, Menstrual Disturbances, And Reduced Bone Mass Among Adolescent Runners With Dietary Restraint

Previously, we found a negative association between elevated dietary restraint and bone mass in female adolescent endurance runners, however diet and energy expenditure were not assessed. PURPOSE: Evaluate energy intake and expenditure, menstrual function, bone mass, and hormones relevant to bone metabolism in a sample of 41 female adolescent runners (age 15.7 ± 0.2y) with normal (N= 28) and elevated (N= 13) levels of cognitive dietary restraint. METHODS: For 7d, runners recorded dietary intake, underwent daily 24hr recalls, and wore a combined accelerometer and heart rate monitor to determine energy expenditure. On the 8th day, runners provided a morning saliva sample, had a fasted blood draw, underwent a dual-energy x-ray absorptiometry scan to measure bone mass and body composition, had height and weight measured, and completed a questionnaire regarding training volume, menstrual function, sports participation history and the Three Factor Eating Inventory to determine cognitive dietary restraint. RESULTS: Girls with elevated restraint were heavier (57.6 ± 2.1kg vs. 52.5 ± 1.4kg, P< 0.05) and trended toward having a higher body fat (%) (24.8 ± 1.7 vs. 21.2 ± 1.2, P= 0.09). However, those with restraint also had a lower relative intake (kcal/kg/d) (37.9 ± 2.6 vs. 44.0 ± 1.8, P= 0.06) and higher total (2218.0 ± 61.2 vs. 2066.5 ± 40.8, P< 0.05) and activity (777.8 ± 46.3 vs. 679.8 ± 30.9, P= 0.09) energy expenditures (kcal/d). Energy availability (kcal/kgFFM/d) was lower, but not significant, in those with elevated restraint (32.5 ± 3.1 vs. 38.9 ± 2.1, P= 0.11). Salivary cortisol (nmol/L) (18.8 ± 2.2 vs. 13.5 ± 1.4, P< 0.05) and leptin (ng/ml) (7.9 ± 0.9 vs. 5.0 ± 0.6, P< 0.05) levels were higher in those with restraint, while estradiol, IGF-1, T3 were not significantly different. Further, runners with elevated restraint exhibited a lower adjusted (BMI, fat free mass) lumbar spine BMD Z-score (-0.84 ± 0.17 vs. -0.18 ± 0.11, P< 0.005) and a higher prevalence of amenorrhea (38.5% vs. 13.0%, P= 0.08). CONCLUSIONS: The lower bone mass and menstrual disturbances currently and previously observed in runners with self-reported elevated cognitive dietary restraint may be due to the development of a chronic energy deficit. Further, evaluating cognitive restraint may serve as a means of assessing runners at risk of developing low bone mass.