The Relationship of Gymnastics Participation in Childhood and Adolescence to Skeletal Development and Maintenance

The objective of this thesis was to investigate low-level impact loading during growth and skeletal development as well as to determine the influence of the withdrawal of the loading stimulus on adult bone parameters. The findings should help to determine whether adolescent and adult bone health benefits from structured physical activity during growth.

Study 1: The purpose of study one was to investigate whether the differences previously reported in the skeleton of competitive female gymnasts (high level gymnastics exposure) are also demonstrated in young children with a current or past participation history in recreational or precompetitive gymnastics (low level gymnastics exposure). One hundred and sixty three children (30 gymnasts, 61 ex-gymnasts, and 72 non-gymnasts) between 4 and 6 years of age were recruited and measured annually for four years. Total body (TB), lumbar spine (LS) and femoral neck (FN) bone mineral content (BMC) was measured by dual energy x-ray absorptiometry (DXA) at each measurement occasion. Bone mass, density, structure and estimated strength was determined using peripheral quantitative computed tomography (pQCT) at the radius and tibia during the third measurement occasion. Multilevel random effects models were constructed and used to predict differences in TB, LS and FN BMC between groups while controlling for differences in body size, physical activity and diet. Analysis of covariance (covariates of sex, age and height) was used to investigate differences in bone content, density, area, and estimated strength at the radius and tibia. Gymnasts had 3% more TB and 7% more FN BMC than children participating in other recreational sports at the fourth measurement occasion (p<0.05). Gymnasts were also found have 6-25% greater adjusted BMC, volumetric bone mineral density and estimated strength at the distal radius compared to non-gymnasts (p< 0.05). These findings suggest that recreational and precompetitive gymnastics participation (low level gymnastics exposure) is associated with greater bone parameters. This is important as beginner gymnastics skills are attainable by most children and do not require a high level of training. Low-level gymnastics skills can easily be integrated into school physical education programs potentially impacting skeletal health.

Study 2: The purpose of study 2 was to assess whether the previously reported greater bone mineral content in premenarcheal gymnasts was maintained 10 years after the cessation of participation and removal of the gymnastics loading stimulus. In 1995, thirty elite premenarcheal female gymnasts were recruited into a study investigating the role of high impact physical activity on bone mass in childhood and compared to 30 non-gymnasts. In 2009-2010 gymnasts and non-gymnasts (n=60) were re-contacted and 25 retired gymnasts and 22 non-gymnasts consented to participate. Total body, LS, and FN BMC was assessed at both measurement occasions by DXA. Bone geometric and densitometric parameters were measured by pQCT at the radius and tibia in 2009/10. ANCOVA was used to compare gymnasts' and non-gymnasts' bone parameters while controlling for differences in age, body composition and maturation. Gymnasts had significantly greater size adjusted TB, LS, and FN BMC (15, 17, and 12%, respectively) at 12 years of age (1995) (p< 0.05). At follow-up, retired gymnasts also had significantly greater size adjusted TB, LS, and FN BMC (13, 19 and 13%, respectively) (p< 0.05). Furthermore, retired female gymnasts had greater bone area, content and estimated strength at the radius and greater BMC and estimated strength at the tibia compared to non-gymnasts (p< 0.05). Premenarcheal gymnasts have bone benefits that were apparent in adulthood after long-term removal of the gymnastics loading stimulus. Low level gymnastics exposure was associated with greater bone parameters in childhood. If these benefits can be maintained, as is suggested in retired competitive gymnasts, recreational gymnastics participation has the potential to positively impact lifetime skeletal health. (Abstract shortened by UMI.)