505
The Effect of Amenorrhea on Calcaneal Bone Density and Total Bone Turnover in Runners V. J. Harber, C. E. Webber, J. R. Sutton, J. D. MacDougall Departments of Medicine, Nuclear Medicine and Physical Education, McMaster University, Hamilton, Ontario, Canada, L8N 3Z5
as little as 3 years duration has been shown to lead to irre-
V. J. Harber, C. E. Webber, J. R. Sutton, J. D. MacDougall, The Effect of Amenorrhea on Calcaneal Bone Density and Total Bone Turnover in Runners. lot J Sports Med,Vol 12,No5,pp505—508, 1991.
Accepted: December 30, 1990 To examine in athletes the effect of long-term
amenorrhea on the skeleton, measurements of calcaneal
density and whole body retention of 99mTcimidodi phosphate were made in 42 women who could be allocated to one of 3 groups defined by their level of physical activity and by menstrual status. There was no difference in bone
density between eurnenorrheic normoactive females and either eumenorrheic or amenorrheic athletes. However, calcaneal density was significantly greater for each group than
for previously measured sedentary controls. Total body
bone turnover was greater in both eumenorrheic and amenorrheic athletes than in eumenorrheic normoactive women. Sustained, intense physical activity does not significantly increase calcaneal bone density over and above the increase associated with normal levels of activity. This is
despite a significant increase in the rate of total body bone mineral turnover. Key words
Physical activity, amenorrhea, calcaneal density, whole body bone turnover
Introduction
Reduced spinal bone density in hypoestrogenie amenorrheic athletes has been reported by a number of authors (2, 4). Although intense exercise may reduce the impact of amenorrhea on bone mass (14), athletes may be subjected to a high risk for premature bone loss and bone-related
injuries or skeletal aberrations such as stress fractures and scoliosis (14, 21). More importantly, untreated amenorrhea of
versible trabecular bone loss (3).
Reductions of bone mineral mass are the result of changes in the rate of bone turnover although a change in turnover will not necessarily lead to a loss of bone. Bone is lost
when the formation rate is reduced in relation to the rate of bone resorption. Previous studies of competitive athletes have used static measurements of bone mass and have provided little information regarding skeletal metabolism or bone turnover rate. The aim of the present study was to investigate the effects of long-term amenorrhea on bone density and bone turnover rate in athletes by using both static and dynamic measurements of bone. Materials and Methods
A total of 42 women (19—35 years) were recruited from the University community on a volunteer basis. Each subject was interviewed to exclude a history of dietary disorders and thyroid dysfunction. To exclude other conditions which might affect calcium metabolism and menstrual regularity, testosterone and prolactin concentrations were measured and found to be within the normal range. No subject had used oral contraceptives or other medications known to interfere with menstrual regulation within 12 months prior to testing. All subjects had experienced a normal menarche and were non-smokers while all athletes were members of regional competitive track clubs. Each subject was allocated to one of 3 groups: Group A (eumenorrheic normoactive females) consisting of 14 subjects who reported 9 or more menses per year and who exercised fewer than 3 times per week but did not participate in any formal exercise or activity program; Group B (eumenorrheic athletes) consisting of 17 runners who reported 9 or more menses per year and who trained 7—12 times per week and group C (amenorrheic athletes) consisting of 11 runners who reported no menses in the last 12 months and who trained 7—12 times per week.
The protocol had been approved by the Human Ethics Committee of McMaster University and informed consent was obtained. Age, height, weight and menstrual history were recorded for each subject. In addition estradiol concentrations, maximum oxygen uptake (VO2max) and percent body fat were measured. All plasma samples were stored at — 70 °C and were analyzed within the same assay. In-
traassay variation was approximately 10%. VO2max was Int.J.SportsMed 12(1991)505—508 GeorgThieme Verlag StuttgartNew York
measured by the open circuit method during progressive exercise to exhaustion on a cycle ergometer (20). Percent body fat
Downloaded by: University of British Columbia. Copyrighted material.
Abstract
506 mt. J. Sports Med. 12(1991)
V. J. Harber, C. E. Webber, J. R. Sutton, J. D. MacDougall
Table 1 Physical characteristics of each group (mean standard deviation)
A
Group Number
B 17
14
Age (years) Height (cm) Weight (kg) Estradiol (pmolfI) Age of menarche VO2max (mi/kg/mm) Percent body fat
C 11
26.6 6.7
26.5 5.0
26.0± 6.3
164.4 6.4 63.1 11.6
166.0 5.4
165.0 5.6
60.6 4.5
54.3 4.6
255 13.2± 1.1
300
33.1
24.4 10.9
13.6± 1.6
47.5 9.1 17.7 9.1
76 14.6±1.7
42.2 6.6 18,2± 5.6
Ri 0
>
0a) a)
01 1
A)n=14)
was estimated for each subject based on subcutaneous fat
Fig. 1 The mean calcaneal densities and standard deviations for eumenorrheic controls (A), eumenorrheic runners (B) and amenorrheic runners (C).
The density of weight bearing trabecular bone in the calcaneus was measured in all subjects using the Compton scattering technique (22). The technique is precise and accurate and has a long-term reproducibility of 1.6% (1). Cross-
sectional measurements in 172 normal subjects have established the dependence of density upon body weight, age and sex (16). Calcaneal density reflects the metabolic state of the whole skeleton at least with respect to aging, estrogen deficiency and therapeutic intervention for osteoporosis (17). We have also shown that the density of the calcaneus reflects the density of the spine (1). The range of calcaneal densities which would be associated with the range of ages of enrolled subjects
is 0.01 gcm
60
55
0 C
a)
50
a,
0
resorption, whole body retention also reflects the rate of total body bone turnover (7). We have shown previously that 99mTc imidodiphosphate (IDP) can be used for such measurements (19). Subjects were given an intravenous injection of 99mTC IDP (1.85 MBq) and measured for whole body activity in a
shadow shield whole body monitor at 30 minutes and 24 hours. Differences between groups were examined by one-way analysis of variance.
45 40
ii Ii_I
A(n14)
B(n=17)
C(n= il)
Fig. 2 The mean IDP retention and standard deviations for groups A, B and C.
ent from that for group B (30A
1.2 d). Average duration of
amenorrhea for subjects in group C was 2.5 0.4 years and ranged from 1.5 to 6 years. Groups B and C each had a significantly higher VO2max than Group A (p
The Effect of Amenorrhea on Calcaneal Bone Density and Total Bone Turnover in Runners V. J. Harber, C. E. Webber, J. R. Sutton, J. D. MacDougall Departments of Medicine, Nuclear Medicine and Physical Education, McMaster University, Hamilton, Ontario, Canada, L8N 3Z5
as little as 3 years duration has been shown to lead to irre-
V. J. Harber, C. E. Webber, J. R. Sutton, J. D. MacDougall, The Effect of Amenorrhea on Calcaneal Bone Density and Total Bone Turnover in Runners. lot J Sports Med,Vol 12,No5,pp505—508, 1991.
Accepted: December 30, 1990 To examine in athletes the effect of long-term
amenorrhea on the skeleton, measurements of calcaneal
density and whole body retention of 99mTcimidodi phosphate were made in 42 women who could be allocated to one of 3 groups defined by their level of physical activity and by menstrual status. There was no difference in bone
density between eurnenorrheic normoactive females and either eumenorrheic or amenorrheic athletes. However, calcaneal density was significantly greater for each group than
for previously measured sedentary controls. Total body
bone turnover was greater in both eumenorrheic and amenorrheic athletes than in eumenorrheic normoactive women. Sustained, intense physical activity does not significantly increase calcaneal bone density over and above the increase associated with normal levels of activity. This is
despite a significant increase in the rate of total body bone mineral turnover. Key words
Physical activity, amenorrhea, calcaneal density, whole body bone turnover
Introduction
Reduced spinal bone density in hypoestrogenie amenorrheic athletes has been reported by a number of authors (2, 4). Although intense exercise may reduce the impact of amenorrhea on bone mass (14), athletes may be subjected to a high risk for premature bone loss and bone-related
injuries or skeletal aberrations such as stress fractures and scoliosis (14, 21). More importantly, untreated amenorrhea of
versible trabecular bone loss (3).
Reductions of bone mineral mass are the result of changes in the rate of bone turnover although a change in turnover will not necessarily lead to a loss of bone. Bone is lost
when the formation rate is reduced in relation to the rate of bone resorption. Previous studies of competitive athletes have used static measurements of bone mass and have provided little information regarding skeletal metabolism or bone turnover rate. The aim of the present study was to investigate the effects of long-term amenorrhea on bone density and bone turnover rate in athletes by using both static and dynamic measurements of bone. Materials and Methods
A total of 42 women (19—35 years) were recruited from the University community on a volunteer basis. Each subject was interviewed to exclude a history of dietary disorders and thyroid dysfunction. To exclude other conditions which might affect calcium metabolism and menstrual regularity, testosterone and prolactin concentrations were measured and found to be within the normal range. No subject had used oral contraceptives or other medications known to interfere with menstrual regulation within 12 months prior to testing. All subjects had experienced a normal menarche and were non-smokers while all athletes were members of regional competitive track clubs. Each subject was allocated to one of 3 groups: Group A (eumenorrheic normoactive females) consisting of 14 subjects who reported 9 or more menses per year and who exercised fewer than 3 times per week but did not participate in any formal exercise or activity program; Group B (eumenorrheic athletes) consisting of 17 runners who reported 9 or more menses per year and who trained 7—12 times per week and group C (amenorrheic athletes) consisting of 11 runners who reported no menses in the last 12 months and who trained 7—12 times per week.
The protocol had been approved by the Human Ethics Committee of McMaster University and informed consent was obtained. Age, height, weight and menstrual history were recorded for each subject. In addition estradiol concentrations, maximum oxygen uptake (VO2max) and percent body fat were measured. All plasma samples were stored at — 70 °C and were analyzed within the same assay. In-
traassay variation was approximately 10%. VO2max was Int.J.SportsMed 12(1991)505—508 GeorgThieme Verlag StuttgartNew York
measured by the open circuit method during progressive exercise to exhaustion on a cycle ergometer (20). Percent body fat
Downloaded by: University of British Columbia. Copyrighted material.
Abstract
506 mt. J. Sports Med. 12(1991)
V. J. Harber, C. E. Webber, J. R. Sutton, J. D. MacDougall
Table 1 Physical characteristics of each group (mean standard deviation)
A
Group Number
B 17
14
Age (years) Height (cm) Weight (kg) Estradiol (pmolfI) Age of menarche VO2max (mi/kg/mm) Percent body fat
C 11
26.6 6.7
26.5 5.0
26.0± 6.3
164.4 6.4 63.1 11.6
166.0 5.4
165.0 5.6
60.6 4.5
54.3 4.6
255 13.2± 1.1
300
33.1
24.4 10.9
13.6± 1.6
47.5 9.1 17.7 9.1
76 14.6±1.7
42.2 6.6 18,2± 5.6
Ri 0
>
0a) a)
01 1
A)n=14)
was estimated for each subject based on subcutaneous fat
Fig. 1 The mean calcaneal densities and standard deviations for eumenorrheic controls (A), eumenorrheic runners (B) and amenorrheic runners (C).
The density of weight bearing trabecular bone in the calcaneus was measured in all subjects using the Compton scattering technique (22). The technique is precise and accurate and has a long-term reproducibility of 1.6% (1). Cross-
sectional measurements in 172 normal subjects have established the dependence of density upon body weight, age and sex (16). Calcaneal density reflects the metabolic state of the whole skeleton at least with respect to aging, estrogen deficiency and therapeutic intervention for osteoporosis (17). We have also shown that the density of the calcaneus reflects the density of the spine (1). The range of calcaneal densities which would be associated with the range of ages of enrolled subjects
is 0.01 gcm
60
55
0 C
a)
50
a,
0
resorption, whole body retention also reflects the rate of total body bone turnover (7). We have shown previously that 99mTc imidodiphosphate (IDP) can be used for such measurements (19). Subjects were given an intravenous injection of 99mTC IDP (1.85 MBq) and measured for whole body activity in a
shadow shield whole body monitor at 30 minutes and 24 hours. Differences between groups were examined by one-way analysis of variance.
45 40
ii Ii_I
A(n14)
B(n=17)
C(n= il)
Fig. 2 The mean IDP retention and standard deviations for groups A, B and C.
ent from that for group B (30A
1.2 d). Average duration of
amenorrhea for subjects in group C was 2.5 0.4 years and ranged from 1.5 to 6 years. Groups B and C each had a significantly higher VO2max than Group A (p
