Table 5

Prospective studies on predictive validity of physical fitness for low back pain in children and adolescents

Fitness component	Author/study	Years of follow-up	Subjects	Age (years)	Fitness test	Outcome variables	Results
High-quality studies
Musculoskeletal and body composition	Kujala et al55	1	Boys 58	10.3–13.3	Height, BF (skinfolds thickness), endurance strength of the trunk (curl-ups and back test), maximal isometric strength (trunk extension), tightness of the hip flexor muscles, and the hamstrings muscles, systemic hypermobility and lumbar sagital mobility	Incidence of low back pain during the past 12 months (self-reported)	Boys and girls
	Quality score 3		Girls 80	11–14			Only tightness of the hip flexor muscles was associated with lifetime cumulative incidence of low back pain

Musculoskeletal and motor fitness	Barnekow-Bergkvist et al56	18	Boys 220	16	Muscular endurance (static, back extension; dynamic, curl-up and bench press), strength (static, two-hand lift and hand grip), flexibility (neck lateral flexion and rotation, hip flexion/hamstring flexibility, hip extension/iliopsoas flexibility) and standing balance	Prevalence of symptoms in the neck, shoulders, and low back (self-reported)	Boys and girls
	Quality score 4	1974	Girls 205	16			Boys and girls
		1992	Boys 157	34			Neck-shoulder symptoms: after adjusting for covariation with sociodemographic and individual factors, lifting was negatively related to symptoms. In addition, high performance in the bench press test at the age of 16 years was associated with a decreased risk of neck–shoulder problems in adulthood for the men. A strong handgrip and good neck flexibility in adulthood were negatively related to symptoms
			Girls 121				Low back symptoms: after adjusting for covariates with sociodemographic and individual factors, high performance in the two-hand lift test in the men and high performance in the back extension test in the women were negatively related to symptoms. In addition, high performance in the two-hand lift test at the age of 16 years was associated with a significantly decreased risk of low back problems in adulthood in women
Musculoskeletal fitness	Burton et al57	5	216	11	Lumbar sagittal flexibility, measured using the flexicurve technique	Incidence and lifetime prevalence of low back pain (self-reported)	Boys and girls
Musculoskeletal fitness	Quality score 4	1985–90	216	to 16			There were no statistically significant relationships between flexibility and any of the low back pain variables measured
Musculoskeletal fitness and body composition	Mikkelsson et al60	25	Boys 801	12–17 to 37–42	BMI, sit and reach and 30-s sit-up test	Self-reported low back pain and physician diagnosed tension neck and knee injury	Boys
				12–17 to 37–42			No association between BMI and low back pain was observed in either boys or girls
							Men in the highest baseline flexibility third were at lower risk of tension neck than those from the lowest third (OR 0.51; 95% CI 0.28 to 0.93)
							Men from the highest baseline endurance strength third were at higher risk of knee injury than those from the lowest third (OR 1.96; 95% CI 1.05 to 3.64)
	Quality score 5	1976–2001	Girls 886				The risk of tension neck increased with each unit increase in BMI by 9% in men
							Girls
							Women from the highest baseline endurance strength third were at lower risk of tension neck than those from the lowest third (OR 0.60; 95% CI 0.40 to 0.91)
							An increase of one unit of BMI increased the risk of knee injury by 16%. The risk of tension neck increased with each unit increase in BMI by 5% in women
Body composition	Hestbaek et al59	8	9600 twins	12–22	BMI	No of days with low back pain during the past year at baseline in 1994 and at follow-up in 2002	Boys and girls
	Hestbaek et al59	8	9600 twins	to			No associations were observed between adolescent overweight and adult low back pain
	Quality score 5	1994–2002		20–26

BMI, body mass index; BF, body fat; OR, odds ratio.