Exercise as it relates to Disease/Cross sectional and longitudinal studies on the effect of water exercise in controlling bone loss in Japanese postmenopausal women
This Wikibooks page is an analysis of the journal article "Cross sectional and longitudinal studies on the effect of water exercise in controlling bone loss in Japanese postmenopausal women" by Tsukahara et al. (1994) 
Osteoporosis is a disease characterised by a decrease in bone mineral density and strength, making them brittle, fragile, and more susceptible to breaks and fractures. The loss of bone tissue is a result of hormonal changes, or deficiency of minerals such as calcium and vitamin D. Bone density is influenced by multiple factors such as heredity, oestrogen levels, physical activity, nutrition, and life style. In general, women are at higher risk than men, particular those of postmenopausal age. This study on Japanese postmenopausal women examines the effect of water exercise on bone mineral density, and whether an exercise program improves the awareness of health and daily life of the participants.
Prevalence in Japan
The prevalence of osteoporosis in Japan is estimated to be 11.6 million with 8.4 million women, and 3.2 million men. An average of 90 000 hip fractures are estimated to occur every year, with the incidence rate continuing to increase in both men and women.
Treatment of osteoporosis include calcium and vitamin D supplements, and a range of medicines such as bisphosphonates, hormone replacement therapy (HRT), and selective estrogen receptor modulators (SERMs). Regular physical activity, especially weight-bearing exercises, is also known to play an important role in maintaining and improving BMD.
Where is this research from?
This research was carried out by the Department of Food and Nutrition at Japan Women’s University in Tokyo.
What kind of research was this?
The study on Japanese women involved a cross-sectional study and a longitudinal study. In the cross sectional study, the women were divided into 3 groups: Non-exercisers (n=30), Newcomers (n=40), and Veterans (n=27). The newcomers and veterans groups performed the water exercise, while the non-exercisers served as the control. The longitudinal study consisted of 30 non-exercisers, 15 newcomers, and 20 veterans. Anthropometry and BMD of the subjects were measured 1 year after the initial assessment.
Cross Sectional Study
The cross sectional study involved 97 healthy Japanese postmenopausal women with physical characteristics shown in Table 1 below (mean±SD).
|Number of Subjects||30||40||27|
|Body fat (%)||30.36±1.12||30.19±0.81||30.96±1.46|
The veteran group consisted of women who had an exercise history of 35.2 months on average, whilst the newcomer group were those who had only begun exercise 3 or 4 weeks before. The non-exercisers served as the control group. Informed consent was obtained from all subjects. Body fat percentage was performed using Bioelectrical Impedance Analysis, while BMD of the lumbar spine (L1-L4) was measured using Dual X-ray Absorptiometry (DXA). Furthermore, nutritional analysis was estimated from 3 day dietary records, and compared to Japanese Recommended Dietary Intake. General awareness of health and fitness in daily life was also investigated using questionnaires.
Water Exercise Protocol
The water exercise performed once a week included walking, jumping, and light callisthenics. The 45min session consisted of:
- 10min warm up
- 20min of aerobic exercise and deep breathing (including two Maximum Working Heart Rate Peaks)
- 10min of swimming
- 5min cool down
In the longitudinal study, anthropometry and BMD measurements were taken 1 year after the initial assessment.
Results and findings from the study
The study found that consistently participating in water exercise can prevent bone loss in postmenopausal women. The veterans group showed higher lumbar spine BMD Z-scores than the newcomers and non-exercisers. From the longitudinal study, the exercising groups maintained or showed an increase in BMD, while the non-exercising group showed a definite decrease at the 1 year point.
Nutritional analysis from 3 day dietary records showed that the women had adequate intakes of all nutrients compared to the Japanese RDA. The exception being the non-exercising group had a slight insufficient iron intake.
The result of the general awareness survey showed that there was an improvement in life and health after starting the water exercise program. Many said they had a more positive outlook on daily life and that their physical fitness had increased.
What conclusions can we take from this research?
From this study we can conclude that there is a positive effect of water exercise on bone mineral density. It is well known that regular physical activity is beneficial for osteoporosis, and that exercise is an effective means for preventing, delaying, and treating the disease. This research shows that non weight-bearing activities can be used to control bone loss in postmenopausal women. This is good news as it is often difficult for the elderly to perform weight-bearing exercises due to their decreased physical capabilities and fitness. Furthermore, the study shows that an exercise program indirectly improves the awareness of one’s health, and their outlook on daily life.
Implications and further suggestions
While results show improvements in BMD in the women, it only studied healthy subjects without disease. Thus it is unknown whether water exercise is beneficial for those with osteoporosis. Additionally, the study could have included a group that performed weight-bearing exercises (such as walking, jogging or resistance training). This would show what form of exercise is most suitable for this age and gender group. The long term effectiveness (>1 year) of water exercise on BMD should also be further investigated.
Further information and resources
The followings links provide further information regarding osteoporosis and exercise:
- Exercise Recommendations for Osteoporosis: https://www.iofbonehealth.org/exercise-recommendations
- Osteoporosis and Exercise: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1742726/pdf/v079p00320.pdf
- Journal of Osteoporosis and Physical Activity: http://www.esciencecentral.org/journals/osteoporosis-and-physical-activity.php
- TSUKAHARA, N., TODA, A., GoTO, J., & EZAWA, I. (1994). Cross-sectional and longitudinal studies on the effect of water exercise in controlling bone loss in Japanese postmenopausal women. Journal of nutritional science and vitaminology, 40(1), 37-47.
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