Calcium Kinetic Responses to Exercise
| Status: | Recruiting |
|---|---|
| Healthy: | No |
| Age Range: | 18 - 42 |
| Updated: | 10/13/2018 |
| Start Date: | June 16, 2018 |
| End Date: | August 2019 |
| Contact: | Erin Gaffney-Stomberg, PhD, RD |
| Email: | erin.g.stomberg.civ@mail.mil |
| Phone: | (508) 233-5960 |
Skeletal Hormone and Calcium Kinetic Responses to Load Carriage Exercise in Females
This randomized cross-over study will identify physiological factors that underlie changes in
bone metabolism that could affect skeletal injury risk, to include increases in parathyroid
hormone (PTH) in response to militarily relevant exercise in females. The primary objective
is to determine the hormone and calcium (Ca) response to multiple bouts of load carriage
exercise in females. The investigators hypothesize that PTH will increase after multiple
bouts of load carriage exercise and this increase will be due to disruption in Ca kinetics,
specifically either a decrease in fractional intestinal Ca absorption (FCA) or changes in
bone formation and/or resorption.
bone metabolism that could affect skeletal injury risk, to include increases in parathyroid
hormone (PTH) in response to militarily relevant exercise in females. The primary objective
is to determine the hormone and calcium (Ca) response to multiple bouts of load carriage
exercise in females. The investigators hypothesize that PTH will increase after multiple
bouts of load carriage exercise and this increase will be due to disruption in Ca kinetics,
specifically either a decrease in fractional intestinal Ca absorption (FCA) or changes in
bone formation and/or resorption.
Initial military training (IMT) results in increased risk of stress fracture, particularly
for females as up to 21% of females may sustain a stress fracture during IMT, an incidence
that is approximately 4-fold higher than that for males. Young female adults will undergo two
separate study periods in random order, one will include exercise and the other will not.
Each study period will use dual stable Ca isotope methodology in order to determine Ca
kinetic responses to a militarily relevant exercise, and dietary intake will be controlled.
Kinetic analyses will include fractional intestinal Ca absorption (FCA), Ca flux into bone
(Vo+) and out of bone (Vo-), as well as renal Ca handling. Serial blood samples collected
during the study periods will also be used to determine hormonal responses to exercise. The
treadmill exercise will consist of a 60 minute timed trial with load carriage (30% body
weight) completed three times during the 6 day kinetic period. At the start of the study,
blood will be collected for analysis of Ca and bone-related genetic markers, and habitual
food intake and exercise will be assessed. The information gathered from this trial will be
used to identify physiological responses that can be targeted by future interventions
designed to improve bone responses to training and decrease injury risk in female Warriors.
for females as up to 21% of females may sustain a stress fracture during IMT, an incidence
that is approximately 4-fold higher than that for males. Young female adults will undergo two
separate study periods in random order, one will include exercise and the other will not.
Each study period will use dual stable Ca isotope methodology in order to determine Ca
kinetic responses to a militarily relevant exercise, and dietary intake will be controlled.
Kinetic analyses will include fractional intestinal Ca absorption (FCA), Ca flux into bone
(Vo+) and out of bone (Vo-), as well as renal Ca handling. Serial blood samples collected
during the study periods will also be used to determine hormonal responses to exercise. The
treadmill exercise will consist of a 60 minute timed trial with load carriage (30% body
weight) completed three times during the 6 day kinetic period. At the start of the study,
blood will be collected for analysis of Ca and bone-related genetic markers, and habitual
food intake and exercise will be assessed. The information gathered from this trial will be
used to identify physiological responses that can be targeted by future interventions
designed to improve bone responses to training and decrease injury risk in female Warriors.
Inclusion Criteria:
- Women aged 18-42 years
- No current or prior military service
- Exercise 2-5 x/wk
- Stable body weight for 2 months (±5 lbs)
- Body mass index (BMI) between 19-26 kg/m2
- VO2max between 35-50 ml·kg-1·min-1
- Willing to discontinue use of dietary supplements and abstain from alcohol for the
duration of the study
- Have not donated blood within the last 8 weeks
Exclusion Criteria:
- History of endocrine disorders (e.g., diabetes, uncontrolled thyroid dysfunction,
hypoparathyroidism, or hyperparathyroidism)
- History of bone-modifying disorders (e.g., osteogenesis imperfecta, osteopetrosis, or
rickets)
- History of cardiovascular or renal disease
- Pregnancy or lactation in the last 6 months
- Routine use of medications known to affect bone or calcium metabolism (e.g., thiazide
diuretics, bisphosphonates, oral steroids)
- A very restrictive diet or severe food allergies
We found this trial at
1
site
Natick, Massachusetts 01760
Principal Investigator: Erin Gaffney-Stomberg, PhD, RD
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