Leg tissue mass composition affects tibial acceleration response following impact

Area of Science:

• Biomechanics
• Human Physiology
• Orthopedics

Background:

• Sex-based differences in bone and muscle mass are well-documented.
• The impact of these differences on skeletal response to mechanical loading, particularly during activities like running, remains under-investigated.
• Understanding these responses is crucial for injury prevention and performance optimization.

Purpose of the Study:

• To investigate the influence of sex and body composition on tibial impact response.
• To determine if differences in lean mass, fat mass, and bone mineral content explain sex-based variations in tibial acceleration during impact.

Main Methods:

• Controlled heel impacts were applied to 36 participants (18 males, 18 females) across low, medium, and high body fat categories.
• Tibial response parameters (peak acceleration, acceleration slope, time to peak acceleration) were measured using skin-mounted accelerometers.
• Data were analyzed for un-normalized and normalized responses relative to lean mass, fat mass, and bone mineral content.

Main Results:

• Females exhibited 25% greater peak tibial acceleration than males when un-normalized.
• When normalized for lean mass, wobbling mass, and bone mineral content, females showed significantly higher peak acceleration per gram of tissue (50%, 62%, and 70% greater, respectively).
• Higher lean mass and bone mass were generally associated with decreased acceleration responses.

Conclusions:

• Sex, rather than body fat percentage alone, is a significant factor in tibial impact response.
• Females' lower relative tissue mass contributes to a heightened tibial acceleration response to impact.
• Findings suggest that sex-specific biomechanical adaptations influence skeletal loading during running.