Effect of Intense Training on Ovarian Function and Bone Turnover

NCT ID: NCT02224976

Last Updated: 2016-01-28

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 18 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2014-01-31
• Study Completion Date: 2015-12-31

Brief Summary

The investigators propose a prospective, longitudinal, department funded study protocol to evaluate whether changes in energy availability, during a period of highly intensified exercise training, will increase bone turnover markers and decrease ovarian function and exercise performance, in a dose-dependent fashion in competitive female athletes.

Detailed Description

Female athletes participating in sports which emphasize leanness as a factor to success, while also imposing large exercise training loads, present a high prevalence of endocrine and metabolic alterations linked to low energy stores, including suppressed ovarian function and bone loss. Increased bone turnover resulting from low energy stores and suppressed estrogen production may hold the most adverse consequences for long term health, increasing the risk of premature osteopenia, while increasing the risk of stress fractures in the short term. Chronically low energy stores may also contribute to the development of overreaching and overtraining syndromes, characterized by excessive, lasting fatigue and long-term decreases in performance, which can compromise these athletes' health and athletic career. The investigators propose the first longitudinal study aiming to demonstrate the link between low energy status, impaired ovarian function, bone turnover and decreased performance in free-living, competitive female athletes. After a 4-week baseline period of habitual training, athletes will undergo 4 weeks of intensified training (IT), during which the exercise load is increased by 30% from their individual baseline load in order to sharply increase energy expenditure. As athletes will be let to freely adjust their food intake, the investigators aim to test the hypothesis that athletes will fail to adjust food intake sufficiently to match energy expenditure, and that the resulting decrease in energy availability (EA, energy intake - energy expenditure from exercise) will influence, in a dose-dependent fashion, the suppression of estrogen production, the increase in bone turnover and the severity of performance decrement. The IT period will then be followed by a 2-week taper (REC), in which exercise training volume will be reduced by 50% from baseline. The investigators will assess whether EA returns to baseline values, and characterize changes in bone turnover during this recovery period. It is hypothesized that any improvements in exercise performance resulting from IT + REC will occur in athletes who were able to remain closest to a balanced energy state during IT. Concretely linking EA to both performance and bone health may incentivize female athletes to adopt more adequate feeding behaviors for their activity level.

Conditions

Amenorrhea

Study Design

• Allocation Method: NA
• Intervention Model: SINGLE_GROUP
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: NONE

Study Groups

Intensified training

Volunteers will increase exercise training by 30% from baseline

Group Type: EXPERIMENTAL

Intensified Training

Intervention Type: BEHAVIORAL

Volunteers will increase exercise training by 30% from baseline

Interventions

Intensified Training

Volunteers will increase exercise training by 30% from baseline

Intervention Type: BEHAVIORAL

Eligibility Criteria

Inclusion Criteria

• competitive endurance runners (racing in events ranging from 10km to ultra-marathons)
• training at least 5 days per week over the past 12 months, and more than 30 miles per week
• regular menstrual cycles (24-35 days) over the past 6 months
• maximal oxygen consumption (VO2max) > 50ml/kg/min
• English speaking

Exclusion Criteria

• smoker
• amenorrhea
• pregnant or lactating in the past 2 years
• chronic disease that will affect bone health, metabolism or the cardiorespiratory system
• take medications that have cardiovascular or metabolic effects
• present any contra-indication to exercise testing (cardiovascular abnormalities)
• report any major illness or injury preventing training for more than 4 weeks over the past 3 months
• a history of clinical anorexia nervosa or bulimia nervosa

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 40 Years
• Eligible Sex: FEMALE
• Accepts Healthy Volunteers: Yes

Sponsors

University of California, Davis

OTHER

Sponsor Role: collaborator

USDA, Western Human Nutrition Research Center

FED

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Gretchen A Casazza, PhD

Role: PRINCIPAL_INVESTIGATOR

University of California, Davis

Locations

USDA Western Human Nutrition Research Center

Davis, California, United States

Countries

United States

References

Schaal K, VanLoan MD, Hausswirth C, Casazza GA. Decreased energy availability during training overload is associated with non-functional overreaching and suppressed ovarian function in female runners. Appl Physiol Nutr Metab. 2021 Oct;46(10):1179-1188. doi: 10.1139/apnm-2020-0880. Epub 2021 Mar 2.

Reference Type: DERIVED

PMID: 33651630 (View on PubMed)

Related Links

http://www.ars.usda.gov/Main/docs.htm?docid=11240

USDA Western Human Nutrition Research Center

http://www.ucdmc.ucdavis.edu/sportsmedicine

UC Davis Sports Medicine

Other Identifiers

FL94

Identifier Type: -

Identifier Source: org_study_id