swimming and bone density

It was a rat study. There are, I believe, relevant human studies. I think that, in serious swimmers,
there is a positive effect on the femoral neck ("hip") bone, though less so on the vertebral bodies
(maybe because of the weight bearing effect of pushing off the walls?). I'd predict that swimmers
may be somewhat protected from hip fractures -- less so from vertebral body fractures.

I'll try and look up what literature do exist in people.

Larry Weisenthal

Certitude is poison; curiosity is life

Bibliography of Studies on Bone Density in Human Swimmers

1: J Sports Med Phys Fitness. 1999 Jun;39(2):154-9.

Regional and total body bone mineral density in elite collegiate male swimmers.

Taaffe DR, Marcus R.

Muskuloskeletal Research Laboratory, Veterans Affairs Medical Center, Palo Alto, California, USA.

BACKGROUND: To examine the role of long-term swimming exercise on regional and total body bone
mineral density (BMD) in men. METHODS: Experimental design: Cross-sectional. Setting:
Musculoskeletal research laboratory at a medical center. Participants: We compared elite collegiate
swimmers (n = 11) to age-, weight-, and height-matched non-athletic controls (n =
2). MEASURES: BMD (g/cm2) of the lumbar spine (L2-4), proximal femur (femoral neck, trochanter,
Ward's triangle), total body and various subregions of the total body, as well as regional and
total body fat and bone mineral-free lean mass (LM) was assessed by dual-energy X-ray
absorptiometry (DXA, Hologic QDR
2/A). RESULTS: Swimmers, who commenced training at
3.7 +/- 3.7 yrs (mean +/- SD) and trained for 24.7 +/-
4.2 hrs per week, had a greater amount of LM (p < .05), lower fat mass (p < 0.001) and
percent body fat
(5.5 vs 16.2%, p < 0.001) than controls. There was no significant difference between groups for
regional or total body BMD. In stepwise multiple regression analysis, body weight was a
consistent independent predictor of regional and total body BMD. CONCLUSIONS: These results
suggest that long-term swimming is not an osteogenic mode of training in college-aged males. This
supports our previous findings in young female swimmers who displayed no bone mass benefits
despite long-standing athletic training.

6: Int J Sports Med. 1997 Aug;18(6):408-12.

Bone density and bone metabolic markers in active collegiate athletes: findings in long-distance
runners, judoists, and swimmers.

Matsumoto T, Nakagawa S, Nishida S, Hirota R.

Department of Sports Medicine, Faculty of Physical Education, Kokushikan University, Tokyo, Japan.

We investigated the bone metabolic system status of 103 male and female volunteer collegiate
athletes, who were actively pursuing one of three different sports: Long-distance running (LR); judo
(JU); and swimming (SW). The following parameters were evaluated: total body bone mineral density
(TMBD); bone-forming metabolic markers; serum procollagen type I C-peptide (PICP) levels; bone
alkaline phosphatase (B-ALP) content; bone resorption markers, urinary pyridinoline (Pyd) and
deoxypyridinoline (Dpd) levels. We found that the TBMD and urinary Dpd values in JU athletes were
significantly higher (p < 0.001) than in athletes of

level in male JU athletes was also higher (p < 0.001) than that in the other two groups, but that in
females JU athletes was only higher (p < 0.01) than that in female LR athletes. The PICP levels were
similar to the TBMD values in all groups. No differences in bone density or in bone metabolic
markers were seen in LR

differences in bone mineral density are in part due to the demands of the specific sport, and that
they are reflected in bone metabolic markers. In addition, the status of bone metabolic turnover in
male JU athletes in training may be hypermetabolic and as well as that of female JU athletes with
regular menses cycles.

7: Med Sci Sports Exerc. 1996 Oct;28(10):1243-6.

Bone mineral density in elite 7- to 9-yr-old female gymnasts and swimmers.

Cassell C, Benedict M, Specker B.

Children's Hospital Medical Center, Cincinnati, OH 45229-3039, USA.

It is has been suggested that physical activity may increase bone mineral density (BMD) in children,
thereby preventing development of osteoporosis later in life. We studied 14 gymnasts, 14 swimmers,
and 17 controls to investigate whether participation in different types of sports among girls 7-9 yr
of age is associated with higher total body BMD. Gymnasts were lighter than both swimmers and
controls (P = 0.001), and a larger percent of gymnasts compared with swimmers and controls were
below the 25th percentile for height and weight. Fat mass, percent body fat, and lean mass were less
in gymnasts compared with swimmers and controls (all P < or = 0.05). The relationship between total
body BMD and body weight differed among the three groups (interaction term of weight and sport, P <
.001); the increase in BMD per unit increase in body weight was more among gymnasts than among
swimmers and controls. These results indicate that high impact bone loading activities may lead to
increased bone density among young girls.

8: Pediatr Med Chir. 1992 Sep-Oct;14(5):521-2.

Bone density in swimmers

Radetti G, Frizzera S, Castellan C, Mengarda G.

Divisione Pediatrica, Ospedale Regionale di Bolzano, Italia.

Bone mineral density of the non-dominant forearm was measured by single-photon absorptiometry at a
proximal site (PBMD) and at a more distal site (DBMC) in 9 competitive male swimmers, aged 18 to 23
years, who had been training for 12 +/- 2 years, 10.3 +/- 5.6 hours a week. The results were
compared with 25 age-matched controls. PBMD was m +/- SD 0.57 +/- 0.02 g/cm2 in the swimmers and
0.57 +/- 0.05 g/cm2 in the controls. DBMD was 0.45 +/- 0.02 g/cm2 in the swimmers and 0.45 +/- .03
g/cm2 in the controls. No difference was found between the two groups. We can therefore conclude
that swimming, in absence of gravity, didn't provide our athletes with an effective mechanical load
capable to increase bone density of the forearm.

Larry Weisenthal

Certitude is poison; curiosity is life