Letter to the Editor Standing Long Jump Performance is a Positive Determinant of Bone Mineral Density in Young Adult Women It is generally believed that bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) is the best single predictor of fracture risk espe- cially in elderly women (1,2). Peak BMD attained at the third decade of life is a strong predictor of fracture risk later in life (1,2). Indeed, it was calculated that an increase in peak BMD of 10% would delay the onset of osteoporosis by 13 yr (3). Long-term practice of weight-bearing physical activities stimulates bone for- mation and enhances BMD of stressed sites (4,5). In fact, according to the mechanostat hypothesis, bones adapt their strength to mechanical loads generated from voluntary mechanical usage (6). This has been sup- ported by many animal-based studies (7,8). In humans, it has been shown that body weight and lean mass are the strongest predictors of BMD in both sexes (9,10). Other human-based studies have shown that BMD is correlated to the performances done in some physical tests (11,12). Identifying simple determinants of BMD may be useful for the prevention and early detection of osteoporosis and/or osteopenia. The aim of this study was to explore the relationships between performances in different physical tests (1-maximal repetition [RM] back half-squat, vertical jump, standing long jump test, 3-jump test, and 5-jump test) and BMD of the lumbar spine and the hip in a group of young women. We hypothesized that the objective measures of muscular strength would be corre- lated to BMD of the hip because hip BMD is strongly correlated to mechanical factors on one hand and the physical tests that were used in our study measure the strength and the power of the lower limbs on the other hand. A total of 16 healthy Lebanese women whose ages range from 18 to 30 yr participated in this study. Weight and height were measured and body mass index (BMI) was calculated. Daily calcium intake, daily protein intake (DPI), and sleep quality were evaluated using val- idated questionnaires. The L2eL4 BMD, total hip (TH) BMD, and femoral neck (FN) BMD were measured by DXA. Age, weight, BMI, DPI, and sleep duration were not correlated to BMD values. Height was positively correlated to L2eL4 BMD and TH-BMD ( p ! 0.05). Performances in standing long jump test, 3-jump test, 5-jump test, and 1-RM half-squat were positively correlated to L2eL4 BMD, TH-BMD, and FN-BMD ( p ! 0.05). Using multiple linear regression analysis models, height and performance in long jump test explained 48% of the lumbar spine variance, whereas height and performance in 5-jump test ex- plained 51% and 45% of the TH BMD and FN BMD variances, respectively. This study suggests that perfor- mances in long jump and 5-jump tests are positive deter- minants of lumbar spine and hip BMD in young adult women. Eddy Zakhem Rawad El Hage Sarah Bassil Elie Moussa Laboratoire de Physiologie et de Biom ecanique de la Performance Motrice Universit  e de Balamand Al Koura, Liban Gautier Zunquin Denis Theunynck Laboratoire RELACS D epartement STAPS Universit  e du Littoral C^ ote d’Opale Dunkerque, France References 1. Melton LJ III. 2001 The prevalence of osteoporosis: gender and racial comparison. Calcif Tissue Int 69:179e181. 2. Marshall D, Johnell O, Wedel H. 1996 Meta-analysis of how well measures of bone mineral density predict occurrence of osteoporotic fractures. BMJ 312:1254e1259. 129 Journal of Clinical Densitometry: Assessment of Skeletal Health, vol. 16, no. 2, 129e130, 2013 Ó Copyright 2013 by The International Society for Clinical Densitometry 1094-6950/16:129e130/$36.00 http://dx.doi.org/10.1016/j.jocd.2013.02.015