Site-Specific Effects of Tennis Playing on Muscle Size and Bone Strength in the Dominant Arm of Female Tennis Players
Open Access
- Author:
- Smulofsky, Jaclyn P
- Area of Honors:
- Kinesiology
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Dr. Gaele Ducher, Thesis Supervisor
Dr. Gaele Ducher, Thesis Supervisor
Dr. Mary Jane De Souza, Thesis Supervisor
Stephen Jacob Piazza, Thesis Honors Advisor - Keywords:
- tennis
side-to-side differences
peripheral quantitative computed tomography (pQCT)
bone strength
muscle cross sectional area (MCSA) - Abstract:
- Mechanical loading as experienced while playing tennis induces musculoskeletal adaptations in the dominant arm of tennis players. It is not clear which site in the forearm (radius and ulna) or upper arm (humerus), responds most to loading, and how muscle tissue influences the skeletal adaptations. The aims of this study were: 1) to characterize the site-specific musculoskeletal response to loading and 2) to investigate the relationship between muscle and bone tissues in the upper limbs. Ten female tennis players were recruited from the Penn State Women’s Tennis Team (n=5) and from other clubs (n=5). Bone geometric parameters, volumetric bone mineral density as well as estimates of bone strength (SSI, BSI and J) were examined in both the dominant and nondominant arms of the players at several skeletal sites along the forearm (at 4%, 33%, 50%, and 66% of bone length) and upper arm (at 25% and 50% of bone length), using peripheral quantitative computed tomography (pQCT). All bone parameters were therefore obtained at: 4%, 33%, 50%, 66% radius, 4%, 33%, 50%, 66% ulna and 25%, 50% humerus. Muscle cross-sectional area (MCSA) was also determined by pQCT and lean mass of both upper limbs was measured using dual energy X-ray absorptiometry (DXA). The effect of repetitive loading was quantified by examining the relative side-to-side differences between the dominant and nondominant limbs (%∆). Our findings indicate that the forearm responds more to loading than does the upper arm for MSCA (%∆ 14.8% and 7.7% at the forearm and upper arm, respectively), while the humerus is the bone of the upper limb that shows the greatest adaptation to loading regarding bone strength (%∆ in SSI: 27.7% at the 25% humerus, 13.6% at the 50% radius and 18.1% at the 50% ulna). However, when considering the radius and ulna together as both contributing to forearm bone strength, the side-to-side differences in bone strength appeared greater in the forearm than the upper arm (i.e. humerus). Side-to-side differences in polar moment of inertia (J), an index of bone’s resistance to torsion, ranged from 35 to 37% in the upper arm and 44 to 49% in the forearm (radius + ulna). It was also found that there were differences with regards to bone and muscle asymmetries between the radius, ulna, and humerus. The study indicated a significant relationship between MCSA and bone strength in the playing arm (66% radius R=0.93 p=0.0005, 50% ulna R=0.76 p=0.01, 50% humerus R=0.85 p=0.002) but not the nonplaying arm. This suggests that exercise-induced loading amplifies the relationship between muscle and bone along the dominant arm of tennis players. In conclusion, repetitive loading seems to exert site-specific effects on bone and muscle tissues. Our findings confirm that loading induces musculoskeletal benefits, which supports the notion that regularly engaging in physical activity positively affects bone health. Further research in this field should examine multiple skeletal sites along the bones of interest in order to gain a true understanding of how these bones respond to exercise. Research in this area could also provide more information on injury prevention, more specifically on the etiology of stress fractures.