Parameters of Exercise to Prevent Osteoporosis (OSTEOPOROSISEX)

University of Michigan

Status: Completed

Conditions: Osteoporosis, Postmenopausal

Treatments: Behavioral: Experimental: Two 20 min down trials; Behavioral: Active Comparator: Sedentary trial; Behavioral: Experimental: 40 minute up trial; Behavioral: Experimental: 40 minute down trial; Behavioral: Experimental: Two 20 minute up trials

Study type: Interventional

Funder types: Other; NIH

Identifiers

NCT04063813

HUM00007202

Details and patient eligibility

About

The principal goal of this study is to determine parameters of walking in terms of peak mechanical vertical force, bout duration, and bout spacing that can preserve or increase bone mineral density (BMD) in postmenopausal women. Release of pulses of parathyroid hormone (PTH), growth hormone (GH), and of markers of bone resorption and bone formation will be used as indicators of the osteogenic effects of a short exposure to exercise. When secreted in pulsatile fashion, GH stimulates osteoblast proliferation, particularly in cortical bone (27, 28). Like GH, the pattern of PTH secretion determines the nature of its effect on bone. When it is secreted in pulsatile manner, PTH contributes to bone formation through activation of bone lining cells, differentiation of osteoprogenitor cells, and suppression of bone cell apoptosis .

Full description

A. Hypotheses and specific aims:

Specific aim 1. Measure plasma concentrations of anabolic hormones (parathyroid hormone (PTH) and growth hormone (GH), at sufficient frequency to define the area under the curve (AUC), and of markers of bone formation (osteocalcin, carboxyterminal propeptide of type 1 procollagen (CICP), and bone-specific alkaline phosphatase (ALKP)), and markers of bone resorption (immunoreactive carboxyterminal telopeptide of type I collagen (CTX)) after 40-minutes of treadmill exercise at the relative intensity of 125% of the ventilatory threshold (VT) corresponding to about 1.78 m/sec (4 miles/h), and two intensities of mechanical loading (724, and 1411 N), in healthy postmenopausal women.

Hypothesis 1. Bone formation, as assessed by increases in markers of bone formation and decreases in markers of bone resorption, will be higher in response to dynamic exercise at a level of mechanical loading that produces increased secretion of PTH and GH than to exercise at other loading intensities.

Specific aim 2. Measure plasma concentrations of anabolic hormones), at sufficient frequency to define the area under the curve (AUC), and of markers of bone formation as in specific aim 1, after two 20-minutes of treadmill exercise, separated by 7 h, at the relative intensity of 125% of the ventilatory threshold (VT) corresponding to about 1.78 m/sec (4 mi/h), and two intensities of mechanical loading (724, and 1411 N), in healthy postmenopausal women.

Hypothesis 2. A 7-hour interval separating the two bouts of exercise will have greater bone anabolic effect than the equivalent volume and intensity of exercise performed in a single bout.

Enrollment: 40 patients

Sex: Female

Ages: 50 to 65 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Age 50 to 65 years if naturally post-menopausal, or age 47 if surgically postmenopausal
• Dual energy X-ray absorptiometry (DEXA) Z score above -1
• No endocrine or metabolic disease requiring medication except for hormonally corrected hypothyroidism
• No musculo-skeletal disabilities that would preclude treadmill walking
• Normal electrocardiogram (EKG) and heart health history
• BMI between 24 and 30
• Hematocrit above 32 %
• No hormone replacement therapy (HRT)
• Personal health provider's Release Letter

Exclusion criteria

• Age and BMI outside of the specified range
• Z score below -1
• Medication for presence of metabolic or endocrine disease
• Musculo-skeletal disabilities that would preclude treadmill walking
• Abnormal electrocardiogram (EKG) and heart health history
• Hematocrit below 32%
• Hormone replacement therapy
• Failure to conform to study protocol

Trial design

Primary purpose: Basic Science

Allocation: Non-Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

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40 participants in 5 patient groups

40 minute up trial

Experimental group

Description:

Subjects were subjected to 40 minutes of treadmill exercise at a 6 degree incline and at 75% of maximal effort between 8:00 and 8:40 am. Isocaloric meals were provided at 7:00, 13:00. and 19:00 h.

Treatment:

Behavioral: Experimental: 40 minute up trial

40 minute down trial

Experimental group

Description:

Subjects were subjected to 40 minutes of treadmill exercise at a 6 degree decline and at 45% of maximal effort between 8:00 and 8:40 am. Isocaloric meals were provided at 7:00, 13:00. and 19:00 h.

Treatment:

Behavioral: Experimental: 40 minute down trial

Two 20 minute up trials

Experimental group

Description:

Subjects were subjected to two 20 minutes of treadmill exercise separated by 7 h at a 6 degree incline and at 75% of maximal effort, the first one between 8:00 and 8:40 am and the second one between 15:00 and 15:20 h..Isocaloric meals were provided at 7:00, 13:00. and 19:00 h.

Treatment:

Behavioral: Experimental: Two 20 minute up trials

Two 20 min down trials

Experimental group

Description:

Subjects were subjected to two 20 minutes of treadmill exercise separated by 7 h at a 6 degree incline and at 45% of maximal effort , the first one between 8:00 and 8:40 am and the second one between 15:00 and 15:20 h. Isocaloric meals were provided at 7:00, 13:00. and 19:00 h.

Treatment:

Behavioral: Experimental: Two 20 min down trials

Sedentary trial

Active Comparator group

Description:

No exercise day with isocaloric meals provided at 7:00, 13:00. and 19:00 h.

Treatment:

Behavioral: Active Comparator: Sedentary trial