The Effect of Calcium Intake on Calcium and Bone Metabolism During Load Carriage in Women (En-Bone)

The Effect of Calcium Intake on Calcium and Bone Metabolism During Load Carriage in Women: a Randomised Controlled Trial

This randomised trial will investigate the effect of calcium supplementation on bone and calcium metabolism in women during acute load carriage exercise. This study will test the hypothesis that calcium supplementation before load carriage exercise will attenuate the decline in serum ionised calcium and increase in parathyroid hormone and bone resorption.

Study Overview

• Status: Recruiting
• Conditions: Calcium Deficiency
• Intervention / Treatment: Dietary supplement: Calcium

Detailed Description

Endurance exercise decreases serum ionised calcium and increases parathyroid hormone and bone resorption. These disturbances to calcium homeostasis can be attenuated by calcium supplementation before exercise. 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. It is unknown if military load carriage disturbs calcium homeostasis and whether calcium supplementation before exercise can attenuate this disturbance. This crossover randomised controlled trial will investigate the effect of acute calcium supplementation on bone and calcium metabolism in women during acute load carriage exercise. Each participant will complete two 2 h load carriage trials. The trials will be performed after either consuming 1000 mg of calcium one hour before or with no treatment. During each experimental trial blood and urine will be sampled for markers of bone and calcium metabolism.

Primary Outcome: The absolute change in urine calcium balance (Ca44:Ca42) between pre- and post-load carriage will be compared between the non-supplemented (Control) and calcium supplemented trial (Supplement) using one-way ANCOVAs with pre-load carriage calcium balance (either as a ratio, or both the numerator and denominator) as the covariate, or a linear mixed model with the restricted maximum likelihood estimation to allow incorporation of incomplete data.

Secondary Outcomes: Circulating measures of bone turnover and calcium metabolism during load carriage will be compared between Control and Supplement using linear mixed models with the restricted maximum likelihood estimation to allow incorporation of incomplete data.

• Study Type: Interventional
• Enrollment (Anticipated): 40
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Thomas J O'Leary, PhD; Email: thomas.oleary100@mod.gov.uk
• Study Contact Backup: Name: Charlotte V Coombs, PhD; Email: charlotte.coombs102@mod.gov.uk

Study Locations

• United Kingdom
  • Surry
    • Camberley, Surry, United Kingdom, GU15 4PQ
      • Recruiting
      • Army Health and Performance Laboratory
      • Contact: Thomas J O'Leary, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 36 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

1. Female sex;
2. Aged 18 to 36 years old;
3. Maximal rate of oxygen uptake of ≥ 35 ml∙kg-1∙min-1;
4. Weight stable (no change in self-reported body mass ≥ 5% over the previous 3 months);
5. BMI between 18 and 30 kg∙m2;
6. Not pregnant.

Exclusion Criteria:

1. Evidence of disordered eating (≥ 20 on the EAT-26);
2. Self-reported change in body mass of ≥ 5% over the previous 3 months;
3. Vitamin D deficient (total 25(OH)D < 30 nmol∙L-1);
4. Maximal rate of oxygen uptake of < 35 ml∙kg-1∙min-1;
5. Total body BMD T-score of < -1;
6. Evidence of menstrual disturbance (oligomenorrhoea: < 9 menstrual cycles in previous 12 months or amenorrhoea: ≤ 3 menstrual cycles in the previous 12 months);
7. Pregnant;
8. Current smoker, or stopped smoking within the last three months;
9. Taking any medications known to affect bone or calcium metabolism (e.g. treatment for thyroid disorders);
10. Self-declared history of heart, liver or kidney disease, diabetes or thyroid disorder;
11. Self-reported stress fracture or any other bone injuries in the previous 12 months;
12. Anaemia (haemoglobin <12 g∙/dL-1).
13. Currently using the implant, injection, or the progesterone-only pill ('mini pill').

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Calcium Supplementation; 1000 mg of calcium carbonate one hour before exercise	Dietary supplement: Calcium; Daily calcium food supplement.
No Intervention: No Calcium Supplementation; No calcium supplementation

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in calcium balance.	The ratio of the calcium isotopes Ca44:Ca42 in spot urine samples.	Before and immediately after exercise.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Circulating calcium isotopes during load carriage.	The ratio of the calcium isotopes Ca44 and Ca42 (Ca44:Ca42) in blood.	Before and immediately after exercise.
Bone turnover during load carriage.	Circulating concentration of procollagen type 1 N-terminal propeptide (P1NP), beta carboxy-terminal cross-linking telopeptide of type 1 collagen (βCTX), osteocalcin, and sclerostin.	0, 20, 40, 60, 80, 100, and 120 minutes during, and 15, 30, 60 and 90 minutes following, exercise.
Calcium metabolism during load carriage.	Circulating concentration of ionized calcium, phosphate, and intact parathyroid hormone.	0, 20, 40, 60, 80, 100, and 120 minutes during, and 15, 30, 60 and 90 minutes following, exercise.
Dermal calcium loss.	Concentrations of total calcium and the ratio of the calcium isotopes Ca44 and Ca42 (Ca44:Ca42) in sweat.	During exercise.

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in muscle strength during load carriage.	Loss of muscle strength in the knee extensors and flexors measured by Biodex in response to load carriage exercise.	Before and immediately after exercise.

Collaborators and Investigators

• Sponsor: Army Health Branch, British Army
• Collaborators: University of East Anglia; Osteolabs, GEOMAR

Study record dates

Study Major Dates

• Study Start (Actual): March 24, 2022
• Primary Completion (Anticipated): May 19, 2023
• Study Completion (Anticipated): May 19, 2023

Study Registration Dates

• First Submitted: July 7, 2020
• First Submitted That Met QC Criteria: March 29, 2021
• First Posted (Actual): March 30, 2021

Study Record Updates

• Last Update Posted (Actual): April 21, 2023
• Last Update Submitted That Met QC Criteria: April 20, 2023
• Last Verified: April 1, 2023

More Information

Terms related to this study

• Keywords: Military; Calcium; Bone Metabolism; Stress Fracture
• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Calcium-Regulating Hormones and Agents; Calcium
• Other Study ID Numbers: 1021/MODREC/19

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Data will be owned by UK Ministry of Defence, not the Principal Investigator. Data will be made available where possible by the Principal Investigator assuming the appropriate approvals are granted by the UK Ministry of Defence.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No