Table 2.

Study characteristics.

Reference	Study Type	Participants	Methods (Stress Fracture Diagnosis)	Occupational Training Program	Methodological Quality Rating (%)
Cosman et al. (2013) [15]	Prospective cohort	Total: n = 891	Orthopedist assessment X-ray	United States Military Academy Cadet Training	High (91)
		U.S. Military Academy cadets
		Male: n = 755
		Mean ± SD Age: 18.7 ± 0.8 years;	CT scan or MRI
		Female: n = 136
		Mean ± SD Age: 18.4 ± 0.8 years
Cowan et al. (2012) [22]	Prospective cohort	Total: n = 1568	At least two encounters with the same diagnosis, using ICD-9 codes 733.93 (tibia or fibula), 733.94 (metatarsals) and 733.95 (other bone)	Army Basic Training	Good (73)
		Females entering the U.S. Army
Dixon et al. (2018) [1]	Prospective cohort	Total: n = 1065	Not detailed	32 Week Royal Marine Training Program	High (82)
		UK Royal Marine recruits
Knapik et al. (2012) [3]	Retrospective cohort	Total: n = 583,651	ICD-9 codes	10 weeks of basic training	High (100)
		U.S. military recruits from databases of the Armed Forces Health Surveillance
		Females: n = 10,706
		Males: n= 475,745
Knapik et al. (2018) [38]	Cross-sectional	Total: n = 583,651	ICD-9 codes 733.1–733.19 and 733.93–733.98	Army Basic Training	High (85)
		U.S. military recruits
		Males: 475,745
		Females: 107,906
Kucera et al. (2016) [27]	Prospective cohort	Total: n = 9811 U.S. military cadets	ICD-9 codes	2-month U.S. cadet Basic Training	Good (73)
Lappe et al. (2001) [34]	Prospective cohort	Total: n = 3758 female U.S. military recruits	Clinical assessment X-ray or CT scan	8-week U.S. Basic Military Training including:	High (82)
				(1) March 225 km on gravel roads carrying a 10 kg pack and rifle
				(2) Run 135 km on asphalt roads
				(3) Approximately 1 h/day of physical training
				(4) Traverse an ‘agility course’ four times during the last 4 weeks
Nunns et al. (2015) [9]	Prospective cohort	Total: n = 1065 UK Royal Marine recruits	Medical examination	Royal Marine 32-week training program	Good (73)
		Logistic regression analysis to assess potential risk factors focused on subsamples of recruits who sustained a tibial stress fracture (n = 10) and an injury-free group (n = 120)	MRI
Pihlajamäki et al. (2019) [35]	Prospective cohort	Total: n = 4029 male Finnish military recruits	ICD-9 or ICD-10 diagnosis codes indicating stress fracture	8 weeks of basic military training including:	High (82)
				-17 h per week of combat skills, marching and other physically demanding training
				-Carrying heavy loads
Pihlajamaki et al. (2006) [37]	Retrospective cohort	Total: n = 4029 male Finnish military recruits	Clinical examination	8 weeks of basic military training including:	Good (73)
			X-ray	-17 h per week of combat skills, marching and other physically demanding training
			MRI or CT scan	-Carrying heavy loads
Rauh et al. (2006) [8]	Prospective cohort	Total: n = 824 female U.S. Marine Corps recruits	Clinical examination	Marine Corps Recruit depot basic training	High (91)
			X-ray
			CT scan
Schaffer et al. (2006) [18]	Prospective cohort	Total: n = 2962 female U.S. Marine Corps recruits	Clinical presentation with diagnostic imaging (X-ray, bone scan or both)	13-week U.S Marine Corps basic training	High (82)
		Aged 17–33 years
Sanchez-Santos et al. (2017) [16]	Case-control	Total: n = 1082 UK Royal Marine recruits aged 16–33 years, including 86 cases with stress fractures	Clinical examination	32 weeks of Royal Marine training	Good (77)
			X-ray
			CT scan
Scheinowitz et al. (2017) [19]	Prospective cohort	Total: n = 226 female Israeli military recruits	Clinical examination	16-month combat Army Basic Training program in the Israeli Defense Forces	Good (64)
			X-ray
			CT scan
Sormaala et al. (2006) [36]	Retrospective cohort	Total: n = 30 male Finnish military recruits, age range 18–26 years	Physical examination by orthopaedic surgeon	Military Training Program	High (82)
			X-ray
			CT scan
Zhao et al. (2016) [21]	Prospective cohort	Total: n = 1398 male Chinese infantry recruits	Clinical examination	8-week training program including marching, running, training exercises and stationary standing procedures	High (82)
			X-ray