The Effect of Calcium Intake and Low Energy Availability on Calcium and Bone Metabolism During Load Carriage in Women

  • STATUS
    Recruiting
  • End date
    Sep 18, 2022
  • participants needed
    45
  • sponsor
    Army Health Branch, British Army
Updated on 18 June 2021

Summary

This randomised trial will investigate the effect of low energy availability (energy intake minus exercise energy expenditure), and calcium supplementation during low energy availability, on bone and calcium metabolism in women during acute load carriage exercise. This study will test the following hypotheses: i) low energy availability will result in an uncoupling of bone turnover and a negative calcium balance during load carriage; ii) calcium supplementation during low energy availability will attenuate the increase in bone resorption and negative calcium balance.

Description

Military field exercises are characterised by high exercising energy expenditures, restricted dietary intake and prolonged periods of load carriage. These exercise and nutritional challenges can result in impaired bone turnover, a negative calcium balance and an increased risk of stress fracture. Women have increased sensitivity to metabolic and endocrine disturbances associated with energy deficit, and have a higher incidence of stress fracture during military training compared with men. This randomised trial will investigate the effect of low energy availability (energy intake minus exercise energy expenditure), and calcium supplementation during low energy availability, on bone and calcium metabolism in women during acute load carriage exercise. This randomised controlled trial will randomise women into three groups, stratified by aerobic fitness, body mass index and contraception. Each participant will complete two 6-day experimental testing sessions before (baseline) and after (follow-up) 2 weeks of an experimental diet: Group 1) adequate energy (45 kcalkg fat free mass [FFM]d-1) / adequate calcium (1500 mgd-1); Group 2) low energy availability (15 kcalkg FFMd-1) / adequate calcium (1500 mgd-1), and; Group 3) low energy availability (15 kcalkg FFMd-1) / low calcium (250 mgd-1). Each 6-day trial will involve three bouts of load carriage (9.7 km in 90 minutes carrying 20 kg), separated by 24 to 48 hours recovery whilst remaining on the experimental diet. During each experimental trial blood and urine will be sampled for markers of bone and calcium metabolism, and endocrine function. Following the completion of the second, 6-day experimental trial, participants will return to their habitual diet for 2 weeks and then provide a recovery blood and urine sample.

Primary Outcome: The absolute change in urinary calcium balance (Ca44:Ca42) from Experimental Testing 1 to 2 will be compared between groups (Group 1 vs Group 2 and Group 2 vs Group 3) using one-way ANCOVAs with calcium balance (either as a ratio, or both the numerator and denominator) in Experimental Testing 1 and baseline body mass as the covariates, or a linear mixed model with the restricted maximum likelihood estimation to allow incorporation of incomplete data.

Secondary Outcomes: Absolute change for AUC for circulating measures of bone turnover and calcium metabolism during load carriage from Experimental Testing 1 to 2 will be compared between groups using one-way ANCOVAs (Group 1 vs Group 2 and Group 2 vs Group 3) with AUC in Experimental Testing 1 as the covariate, or a linear mixed model with the restricted maximum likelihood estimation to allow incorporation of incomplete data. Absolute change for fasting circulating measures of bone turnover, calcium metabolism and endocrine function from Experimental Testing 1 to 2 will be compared between groups (Group 1 vs Group 2 and Group 2 vs Group 3) using one-way ANCOVAs with baseline measures in Experimental Testing 1 as the covariate, or a linear mixed model with the restricted maximum likelihood estimation to allow incorporation of incomplete data. A mixed-design 3 3 (Group [Group 1 vs Group 2 vs Group 3] time [Experimental Testing 1 vs Experimental Testing 2 vs Recovery]) ANOVA will be used to examine changes in body mass, lean mass, fat mass and aBMD.

Details
Condition Calcium Deficiency
Treatment calcium, Low energy availability
Clinical Study IdentifierNCT04823156
SponsorArmy Health Branch, British Army
Last Modified on18 June 2021

Eligibility

Yes No Not Sure

Inclusion Criteria

Female sex
Aged 18 to 36 years old
Maximal rate of oxygen uptake of 35 mlkg-1min-1
Currently either taking no hormonal contraceptives or the combined oral contraceptive pill
Weight stable (no change in self-reported body mass 5% over the previous 3 months)
BMI between 18 and 30 kgm2
Not pregnant

Exclusion Criteria

Evidence of disordered eating ( 20 on the EAT-26)
Habitual energy intake of < 35 kcalkg FFMd-1
Self-reported change in body mass of 5% over the previous 3 months
Vitamin D deficient (total 25(OH)D < 30 nmolL-1)
Maximal rate of oxygen uptake of < 35 mlkg-1min-1
Total body BMD T-score of < -1
Evidence of menstrual disturbance (oligomenorrhoea: < 9 menstrual cycles in previous 12 months or amenorrhoea: 3 menstrual cycles in the previous 12 months)
Pregnant
Current smoker, or stopped smoking within the last three months
Taking any medications known to affect bone or calcium metabolism (e.g. treatment for thyroid disorders)
Self-declared history of heart, liver or kidney disease, diabetes or thyroid disorder
Self-reported stress fracture or any other bone injuries in the previous 12 months
Anaemia (haemoglobin <12 g/dL-1)
Clear my responses

How to participate?

Step 1 Connect with a site
What happens next?
  • You can expect the study team to contact you via email or phone in the next few days.
  • Sign up as volunteer to help accelerate the development of new treatments and to get notified about similar trials.

You are contacting

Investigator Avatar
Name

Primary Contact

site
Name

0/250
Preferred Language
Other Language
Please verify that you are not a bot.

Additional screening procedures may be conducted by the study team before you can be confirmed eligible to participate.

Learn more

If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

Learn more

Complete your scheduled study participation activities and then you are done. You may receive summary of study results if provided by the sponsor.

Learn more

Similar trials to consider

Loading...

Not finding what you're looking for?

Every year hundreds of thousands of volunteers step forward to participate in research. Sign up as a volunteer and receive email notifications when clinical trials are posted in the medical category of interest to you.

Sign up as volunteer

user name

Added by • 

 • 

Private

Reply by • Private
Loading...

Lorem ipsum dolor sit amet consectetur, adipisicing elit. Ipsa vel nobis alias. Quae eveniet velit voluptate quo doloribus maxime et dicta in sequi, corporis quod. Ea, dolor eius? Dolore, vel!

  The passcode will expire in None.
Loading...

No annotations made yet

Add a private note
  • abc Select a piece of text from the left.
  • Add notes visible only to you.
  • Send it to people through a passcode protected link.
Add a private note