The study is a genetic historical cohort study in a military combat recruits - this study does not examine a specific treatment but rather examines a statistical link between medical history of traumatic fractures, clinical diagnosis of stress fractures and the presence of unique SNPs in subjects DNA.

Finding a statistically significant correlation between SNPs associated with BMD - Osteoporosis, with recruits who were diagnosed with Stress Fractures during basic and advanced infantry training. Greatest importance will be shown in the power calculation: we suggest that the P-value threshold value of the selected SNPs be adjusted downwards to a lower threshold of P <1.0x10-3 (i.e. equal to 50 independent tests).

We will examine the presence or absence of 96 SNPs - 76 SNPs that were previously validated as significant with low BMD or Osteoporosis and 20 SNPs offered for Stress Fractures with recruits who were diagnosed with Stress Fractures during basic training (basic training lasts four months - six months) using SNP Genotyping Analysis-TaqMan Assays. The buccal swab will be taken from recruits who served for at least four months and up to six months in the IDF - Infantry Corps. Buccal swabs will be taken at a single meeting from recruits serving between 4 and 6 months in the IDF - Infantry Corps, which will be used to compare using SNP Genotyping Analysis-TaqMan Assays with the SNPs listed above. In addition, in this single meeting, the recruits will fill out a questionnaire in which they will be asked whether they experienced traumatic fracture from their youth to the time of filling the questionnaire (recruits who experienced traumatic fractures but are not diagnosed with stress fractures constitute as a control group in the research).

There will be one meeting with recruiters who served for at least four months and up to six months in the IDF - infantry. At this meeting, the recruits will be sampled with a buccal swab and fill out a questionnaire.

Inclusion Criteria:

• All participants (440) in the research are male.
• All participants (440) are recruits who serve 4-6 months in the IDF - infantry - basic training.
• 110 recruits with a stress fracture diagnosis in their medical portfolio.
• 110 recruits who have Section 4161x flaw (section Eclipse: a long bone fracture)
• 220 recruits without the aforementioned impairment clause and the above mentioned diagnosis (referred as control group).

Exclusion Criteria:

• Recruit who left the unit before conducting the research.
• A recruiter who did not complete his training due to a course that lasted over two weeks while carrying out basic training.
• A recruiter who did not complete his basic training due to absenteeism.
• A recruiter who has not completed his basic training due to problems with the service conditions.
• A recruiter who has not completed his basic training due to the reduction of a medical profile.
• A recruiter who did not complete his basic training due to a decrease in the recruitment cycle.

440 male infantry recruits training in an IDF (the Israel Defense Forces) boot camp in Israel

Data will be published after statistical analysis only.