According to the world health organization definition of osteoporosis, the disease affects approximately 6.3% of men over the age of 50 and 21.2% of women over the same age range globally.1, 2, 3 Men account for 25% of hip fractures occurring in the over 50 population.4 The overall mortality is about 20% in the first 12 months after hip fracture and is higher in men than women.4, 5, 6, 7 A 10% loss of bone mineral density (BMD) in the hip can result in a 2.5 times greater risk of hip fracture.8, 9, 10 Although low BMD confers increased risk for fracture, most fractures occur in postmenopausal women and elderly men without a densitometric diagnosis of osteoporosis.11, 12, 13 Accordingly, it appears that BMD measurement alone is not sufficient to adequately predict future fracture risk.14 Currently, there is significant evidence showing that body size and femoral neck geometry contribute to fracture risk independently of BMD.14,15 Karlamangla et al.14 developed the concept of composite indices of femoral neck strength (compression strength index [CSI], bending strength index [BSI] and impact strength index [ISI]) based on theoretical considerations from a biomechanical viewpoint. These indices integrate body size, femoral neck size, and femoral neck BMD to capture the structural contributions to bone strength (resistance to fracture forces) relative to load (forces placed on the hip during a fall).14 These indices associate inversely with incident hip fracture risk in elderly women from different countries.14, 15, 16 A study conducted on Lebanese postmenopausal women has shown that CSI is associated with history of osteoporotic fractures.16 Previous studies have identified several correlates of composite indices of femoral neck strength in several populations.17, 18, 19, 20, 21, 22, 23, 24 It has been shown that insulin resistance is associated with low composite indices of femoral neck strength while serum vitamin D is positively correlated to these bone indices.25,26 Also, we have previously shown that indices of obesity such as BMI and fat mass percentage are negatively correlated to composite indices of femoral neck strength in young men.27 In addition, we have recently demonstrated that vertical jump, physical activity level (h/week) and relative maximal oxygen consumption (mL/mn/kg) are positively correlated to these bone indices in young adults and middle-aged men.28, 29, 30 Furthermore, handball and soccer practices are associated with greater composite indices of femoral neck strength in men.31,32 In a recent study, we have demonstrated that relative muscular strength of lower limbs (1-RM half-squat/body weight) is positively correlated to composite indices of femoral neck strength in young men.33 Since relative muscular strength of lower limbs and sprinting performance (m/sec) are strongly related,33 we hypothesized that sprinting time and composite indices of femoral neck strength would be negatively correlated. Lately, we have demonstrated that sprinting performance correlates with composite indices of femoral neck strength in a group of young inactive men.34 In the current study, we aimed at verifying whether such correlations are present in middle-aged active men. Age and physical activity level affect the relationships between physical performance variables and composite indices of femoral neck strength.17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 The aim of the current study was to investigate the relationships between 20-meter sprinting time and composite indices of femoral neck strength (CSI, BSI and ISI) in a group of middle-aged active men.