Table 5

Characteristics of Quantitative Studies

First Author, Country, Study Design	Year	Total participants	Clinical condition	Age (years)		Female sex No, (%)	Interventions
				Mean/ median	SD/ range		Intervention	Comparison
Spinal manipulation
Evans (United States) RCT [33]	2018	185	Adolescents (12–18 years) with nonspecific LBP with or without leg pain, VAS ≥ 3/10; subacute/recurrent (current episode 2–12 weeks duration with at least one similar episode in the past year) or chronic (current episode ≥ 12 weeks duration)	I: 15.5 C: 15.3	I: 1.6 C: 1.8	I: 65 (70%) C: 62 (67%)	Type: SMT + Exercise SMT: provided by chiropractors; techniques: high velocity low amplitude (preferred), low velocity low amplitude mobilization, flexion-distraction or drop-table assisted; up to a few minutes of ice/heat or soft tissue massage as needed Duration: 12 weeks Frequency: 1–2 x/week (20-min sessions); 8–16 sessions total Setting: clinic Exercise: provided by chiropractors or exercise therapists; self-care education; supervised sessions; components: aerobic, stretching, strengthening; home exercises accompanied by 20–40 min of aerobic activity Duration: 12 weeks Frequency: Supervised exercises: 1-2x/week (45-min sessions), 8–16 sessions total; Home exercises: 2x/week Setting: clinic/home	Type: Exercise (provided by chiropractors or exercise therapists; self-care education; supervised sessions; components: aerobic, stretching, strengthening; home exercises accompanied by 20–40 min of aerobic activity) Duration: 12 weeks Frequency: Supervised exercises: 1-2x/week (45-min sessions), 8–16 sessions total; Home exercises: 2x/week Setting: clinic/home
Selhorst (United States) RCT [22]	2015	35	Adolescents (13–17 years) with nonspecific LBP < 90 days duration	14.88	1.27	21 (62%)	Type: SMT + Exercise SMT: provided by physical therapists; technique: side-posture lumbar manipulation performed on symptomatic side Duration: 1 week Frequency: 2x/week Setting: Clinic Exercise: provided by physical therapist; components: lumbar stabilization, range of motion, postural training, core strengthening, stretching, addition of high-level functional exercises as indicated to promote return to activity Duration: 4 weeks Frequency: 2x/week Setting: Clinic	Type: Sham SMT + Exercise Sham SMT: provided by physical therapists; technique: patient side-lying, therapist passively flexed both hips to achieve slight lumbar flexion at patient’s most painful vertebral level, equal and opposite force applied to spinous process with both hands without inducing motion Duration: 1 week Frequency: 2x/week Setting: Clinic Exercise: provided by physical therapist; components: lumbar stabilization, range of motion, postural training, core strengthening, stretching, addition of high-level functional exercises as indicated to promote return to activity Duration: 4 weeks Frequency: 2x/week Setting: Clinic
Group-based exercise
Fanucchi (South Africa) RCT [34]	2009	72	Children (12–13 years) with low back pain in the previous three months	12.3	0.7	I: 15 (38.5%) C: 18 (54.6%)	Type: Progressive exercise (instruction provided by PT; 10–15 min educational session about the importance of exercise, core musculature, posture and spinal alignment; weekly home exercise program including class-taught exercises; continuation of normal physical education classes, sports, and physical activity) Duration: 8 weeks Frequency: 1x/week (40–45 min sessions) Setting: School	Type: Control (no intervention; continuation of normal physical education classes, sports, and physical activity) Duration: 8 weeks Frequency: N/A Setting: N/A
Harringe (Sweden) Cohort study [40]	2007	With and without LBP: 51 (I: 33; C: 18) With LBP: 24 (I: 15; C: 4)	Female top level national gymnasts (11–16 years) with LBP (pain between the 12th rib and gluteal folds) more than 1 day during a 4-week baseline period	I: 13 C: 14	I: 11–15 C: 12–16	I: 15 (100%) C: 4 (100%)	Type: Specific segmental muscle control exercises (group training program provided by PT; abdominal hollowing with progression: prone, four-point kneeling, prone with diagonal elevation of arm and leg, standing on balance board, in a basic trampette jump; 10 repetitions using 10-s holds; pressure biofeedback unit used initially to ensure correct muscle contraction) Duration: 8 weeks Frequency: 3–4 times/week Setting: Gymnasium	Type: Control (visits provided by PT; given time for questions regarding injuries; provided advice and regime) Duration: 8 weeks Frequency: 3–4 times/week Setting: Gymnasium
Jones (1262 and 1267) (United Kingdom) RCT [35, 36]	2007	62	Adolescents (Grade 9 and 10 students) with recurrent nonspecific LBP as determined using a standardized questionnaire	I: 14.6 C: 14.6	I: 0.6 C: 0.5	Not reported	Type: Exercise rehabilitation (group-based; progressive program of strengthening and stabilization, range of motion, and aerobic exercises for the back and lower extremity; standardized with respect to number of exercises, repetitions, progression and schedule) Duration: 8 weeks Frequency: 2 x/week (30-min sessions) Setting: school (home exercise encouraged)	Type: Control (continue normal daily activities) Duration: 8 weeks Frequency: N/A Setting: N/A
Vitman (Israel) RCT [39]	2022	33	Children and adolescents (10 – 18 years) with LBP	I: not reported C: not reported	I: not reported C: not reported	Not reported	Type: Weekly physiotherapy + monthly physiotherapy and home exercise Weekly physiotherapy: 45-min group session with two physiotherapists, 21-exercise group therapy program Duration: 12 weeks Frequency: 1x/week Setting: Clinic Monthly physiotherapy and home exercise: same as the comparison group	Type: Monthly physiotherapy (i.e., personally-tailored comprehensive training) and home exercises Physiotherapy: 40-min session consisting of personally tailored training for muscle endurance, flexibility, and strength, as well as instructions on body awareness and application of biomechanical and ergonomic principles Home exercises: 5–6 individualized exercises, 1 set 10 repetitions (10–15 min/day). Diary kept of home practice to monitor Duration: 12 weeks Frequency: 1x/monthy Setting: Clinic
Whole-body vibration
Jung (Korea) RCT [37]	2020	50	Adolescents (10 – 19 years) with LBP ≥ 3 months, VAS ≥ 3/10 and able to perform sit-to-stand movements without assistance	I: 18 C: 18	I: 0.65 C: 0.68	I: 10 (40%) C: 12 (48%)	Type: Whole-body vibration + trunk stabilization exercise Six exercises (squat, bridge, single bridge and knee flex, side bridge, plank) performed on whole-body vibration machine (15 Hz and 2 mm amplitude). Exercise duration was 60 s for single bridge, bridge and knee flex, and plank or 90 secs for squat, bridge, side bridge, performed for 2 sets with 30 s break in between Duration: 12 weeks Frequency: 3x/week Setting: Clinic (supervised by physiotherapist)	Type: Trunk stabilization exercise Six exercises (squat, bridge, single bridge and knee flex, side bridge, plank). Exercise duration was 60 s for single bridge, bridge and knee flex, and plank or 90 secs for squat, bridge, side bridge, performed for 2 sets with 30 s break in between Duration: 12 weeks Frequency: 3x/week Setting: Clinic (supervised by physiotherapist)
Cognitive functional therapy
Ng (Australia) RCT [38]	2015	36	Adolescent male rowers (14–19 years) with nonspecific LBP, VAS > 3/10	I: 16.3 C: 15.2	I: 1.5 C: 1.5	0 (0%)	Type: Cognitive functional approach (provided by a physiotherapist; components: education, discussion about factors contributing to back pain, movement training and body awareness, functional integration, conditioning) Duration: 8 weeks Frequency: 1x/week for first two weeks, 1x/2 weeks for remainder (1 h initial; 30-min subsequent); total 5 sessions Setting: local rowing club or university laboratory	Type: Control (no intervention; free to seek treatment from other providers)
Multimodal care
Ahlqwist (Sweden) RCT [32]	2008	45	Adolescents (12–18 years) with nonspecific LBP (lumbar pain in a defined area); referred by a physician or nurse; VAS > 2/10	I: 15 C: 14	I: 13–18 C: 12–17	I: 15 (65%) C: 16 (73%)	Type: Individualized physical therapy and exercise + standardized home exercise + education Individualized physical therapy and exercise: exercises supervised by a physical therapist (15 reps/exercise; general and specific exercises including conditioning, active and passive mobility, strengthening and coordination; resistance gradually increased); individualized therapy (manual therapy, mechanical diagnostic therapy) Duration: 12 weeks Frequency: 1x/week Setting: clinic Standardized home exercise: body weight for resistance; 2 sets of 10 reps/exercise Duration: 12 weeks Frequency: 2x/week Setting: home Education: functional anatomy, ergonomics, pain management Frequency: 1 session Setting: clinic	Type: standardized home exercise + education Self-training: conditioning exercises (brisk walks, jogging, bicycling, swimming) Duration: 12 weeks Frequency: 3x/week Setting: home; follow-up in clinic at 1 week; follow-up by telephone at 6 weeks Standardized home exercise: body weight for resistance; 2 sets of 10 reps/exercise Duration: 12 weeks Frequency: 3x/week Setting: home Education: functional anatomy, ergonomics, pain management Frequency: 1 session Setting: clinic
Selhorst (United States) Cohort study [41]	2021	16	Adolescent (12 – 19 years) athletes (participating in sport activity ≥ 2 times/week prior to the onset of LBP) who reports acute LBP (< 3 months) that increases during lumbar extension	I: 14.5 C: 15.5	I: 12.1 C: 1.4	I: 5 (62%) C: 3 (38%)	Type: Physical therapist guided functional progression program (PT First) No advanced imaging was obtained at the beginning of the treatment PT First Program 3-phase program: Participants were on rest from their sport Phase I: core strengthening in neutral spine, directional preference if identified, hip strengthening, peri-scapular strengthening, flexibility exercises, manual therapy as needed, modalities for pain (sparingly) Phase II: core strengthening in functional range, hip and peri-scapular strengthening, flexibility exercises, manual therapy (sparingly), light running, jumping Phase III: Return to sport activity with focus on functional return to all aspects of sport Patients who fail to progress after 5 weeks either were treated as a presumed spondylolysis or had advanced imaging. They received two months of rest except for daily activities and home exercise program, following this, they completed physical therapy before returning to sport Duration: Variable Frequency: 2x/week Setting: Clinic	Type: Biomedical model Advanced imaging was obtained to diagnose the injury and participants diagnosed with non-specific LBP or spondylolisthesis Patients with non-specific LBP: physical therapy and progressed to sport immediately Patients with a bony or spondylolytic injury: preliminary 2–3 month rest from activity, bracing if indicated, followed by 4–6 weeks of physical therapy. Physical therapy was individualized based on patient’s presentation Physical therapy: Duration: 4–6 weeks Frequency: 2x/week Setting: Clinic

Abbreviations: C Comparison, I Intervention, LBP Low Back Pain, RCT randomized controlled trial, VAS Visual Analog Scale