Table 3.

Study characteristics. Specific strength vs. non-specific aerobic exercises.

Reference	Characteristics of Participants	Specific Intervention (SI)	Non-Specific Intervention (NSI) + Reference Intervention (REF)	Outcome Measures / Follow-Up Period	Main Results
Andersen et al. [32]	Office workers with neck or shoulder pain > 3/9 and ≥3 m Neck: n = 182, ♀ (44 ± 0.9 y); ♂ (49 ± 1.4 y) Shoulder: n = 94, ♀ (44 ± 1.1 y); ♂ (48 ± 1.4 y) SI group Neck: n = 61 Shoulder: n = 41 NSI group Neck: n = 59 Shoulder: n = 46 REF group Neck: n = 62 Shoulder: n = 37 ITT analysis	Specific neck-shoulder dynamic and static strengthening ex with dumbbells and inelastic strap - 20′ × 3/w for 1 y - 2/3 supervised - during working hours - Load ↑ when they performed > 15 reps/ex - Last 15″: high-speed dynamic power ex (kayaking or ergometer rowing)	General fitness training - 1 h/w during working hours for 1 y - Filled in a “contract”, writing the ways to include + physical act in their lives - Swimming, fitness clubs, all-round strength and aerobic fitness lessons (1–4 visits/m), walking group sessions (step counters), group sessions of Nordic walking, aerobic fitness, etc. REF group - No physical act - Workplace ergonomics, stress management, etc. - =supervision as SI and NSI	Pain: - Pain intensity during last 3 m (0–9 scale) ~ baseline ~ post-intervention (1 y)	Short-term effects (post-intervention): PAIN INTENSITY: - = SI, NSI and REF
Andersen et al. [33]	Same characteristics as Andersen et al. [32] n (at baseline) = 616 397 ♀ (44.6 y); 219 ♂ (45.7 y) (67 excluded/withdrew = 549) SI group n = 180 NSI group n = 187 REF group n = 182 ITT analysis			Pain: - Pain intensity during last 3 m (0–9 scale) - Pain regions (n = 0–11), with a VAS ≥ 3/9 ~ baseline ~ post-intervention (1 y)	Short-term effects (post-intervention): PAIN INTENSITY: - ↓ SI, NSI and REF - ΔSI and ΔNSI > ΔREF Pain regions (n): - ↓ SI and NSI; =REF
Andersen et al. [26]	♀ office workers (30–60 y), assembly line or office workers, with CNSP (≥30 d in the last y), reporting pain ≥ 1 episode/w + pain intensities at T0 ≥ 3 (0–9 scale) + diagnosed as trapezius myalgia. n = 48 ♀ (end 43 ♀) 44 ± 8 y SI group n = 18 ♀. 44 ± 8 y NSI group n = 16 ♀. 49 ± 7 y REF group n = 14 ♀ (end 9 ♀) 48 ± 11 y	5 neck–shoulder specific strengthening ex with dumbbells - 20′ × 3/w supervised for 10 w - 3 sets (25–35″)/ex - High intensity (consecutive concentric and eccentric muscle contractions without pause or breaks) - Load progressively ↑ 12 → 8 RM; (~70 → 80% max intensity)	Bicycle ergometer training - 20′ × 3/w supervised for 10 w - High intensity - Intensity progressively ↑ 50 → 70% (Vo2max) REF group - 1 h/w for 10 w - No physical act - Health counseling on group + on individual level (workplace ergonomics, diet, relaxation, ...) - = supervision as SI and NSI	Pain (diary report): - General pain (VAS1) - Pain at worst (VAS2) - Pain immediately before the session (VAS3) - Pain immediately after the session (VAS4) ~ baseline ~ half of training period ~ post-intervention (10 w) ~ 10 w follow-up	Acute effects after 1 ex session • 1st half of training period: - VAS4-VAS3: ↑ SI; ↓ NSI. Effects lasted for 2 h - ΔNSI > ΔSI and REF • 2nd half of training period: VAS4-VAS3: - ↓ NSI; = SI. Effects lasted for 2 h - ΔNSI > ΔSI and REF Short-term effects (post-intervention): VAS1,2: - ↓ SI; = NSI and REF - ΔSI > ΔNSI and REF Long-term effects (follow-up): VAS1,2: - ↓ SI; = NSI and REF - ΔSI > ΔNSI and REF
Nielsen et al. [25]				PPTs: - Painful trapezius (PPT1) - Non-painful tibialis anterior (PPT2) ~ baseline ~ post-intervention (10 w)	Short-term effects (post-intervention): PPT1: - ↑ SI; = NSI and REF - Δmyalgia < Δcontrols PPT2: - ↑ SI and NSI; =REF - Δmyalgia < Δcontrols
Søgaard et al. [24]	♀ performing monotonous & repetitive work tasks + trapezius myalgia (30–60 y) n = 47 ♀ (end 39 ♀) SI group n = 16 ♀ 44.6 ± 8.5 y NSI group n = 15 ♀ 45.5 ± 8.0 y REF group n = 16 ♀ (end 8 ♀) 42.5 ± 11.1 y			Pain: - At rest (VAS1): measured prior to the repetitive task - During repetitive task (VAS2): pegboard work (40′). VAS every 5′. Changes in VAS slope (time curve) (mm/min)- VAS after 120′ rest immediately before a stressful Stroop task (VAS3). - VAS immediately after the stressful Stroop task (VAS4) ~ baseline (2 d before the intervention) ~ post-intervention (10 w)	Short-term effects (post-intervention): VAS 1: - ↓ SI; = NSI and REF - ΔSI >ΔNSI = ΔREF VAS2: - ↓ NSI; = SI & REF - ΔNSI > ΔSI = ΔREF VAS3, 4: -ΔSI = ΔNSI = ΔREF
Iversen et al. [21]	Patients (16–70 y) + non-specific neck pain ≥ 3 m or ≥ 2 times ≥ 4 w in the past y and worst neck pain in last 2 w NRS ≥ 4 n = 59 (39 ♀ & 20 ♂) (end 31) SI group n = 29 (end 15) 20 ♀ & 9 ♂ 44.6 ± 8.1 y NSI group n = 30 (end 16) 19 ♀ & 11 ♂ 48.2 ± 10.6 y	MDR + 8 neck-shoulder specific strengthening ex. with elastic bands - 3 w MDR: patient education, stress management, group discussions - 9 w SI program: 3 times/w. Supervised at 1st and 3rd w - +1 session NSI - +3 group booster sessions - Yellow–gold Theraband® - Reps/ex until muscular failure - Load progressively ↑: sets/reps/band color - Diary for daily registration	MDR + General fitness training - 3 w MDR: patient education, stress management, group discussions - 9 w NSI program: 1st and 3rd w, 4 and 3 supervised sessions - Introduction to group-based and individual act (circle-training, endurance, low-intensity resistance, stretching) - + 3 group booster sessions - Diary for daily registration	Pain: - Current neck pain (NRS1) - Pain at worst last 2 w (NRS2) - Pain at worst in last 4 w (NRS3) PD: Additional pain sites (n) PPTs: tibialis anterior muscle ~ baseline ~ post-intervention (12 w)	Short-term effects (post-intervention): NRS, pain sites and PPTs: - = SI and NSI - ΔSI = ΔNSI
Rolving et al. [23]	Patients on sick leave from work (4–16 w prior to study) due to non-specific neck pain (18–60 y) n = 83 (60 ♀ & 23 ♂) (end 71) SI group n = 43 (end 34) 27 ♀ & 16 ♂ 39.6 ± 9.2 y NSI group n = 40 (end 37) 33 ♀ & 7 ♂ 39.0 ± 11.0 y ITT analysis	General fitness training and 4 specific neck–shoulder-strengthening ex. With elastic band - 15–20′ supervised training ≥ 3 times/w for 12 w - Participants instructed to be physically active ≥ 30′/d, 3–4 h/w - 3 × 5 reps/ex - Load progressively ↑/2 w - Diary for daily registration	General fitness training - Participants instructed to be physically active ≥ 30′/d, 3–4 h/w for 12 w - Minimal supervision - Diary for daily registration	Pain: - Pain intensity during last w (0–10 scale) (NRS) ~ baseline ~ post-intervention (12 w)	Short-term effects (post-intervention): NRS: - ↓ SI and NSI - ΔSI = ΔNSI.
Saeterbakken et al. [22]	♀ office workers with neck or shoulder pain ≥ 2 and ≥ 3 m n = 34 ♀ (end 31 ♀) SI group n = 13 (end 12) 47.6 ± 11.9 y NSI group n = 10 (end 9) 41.0 ± 15.3 y REF group n = 11 (end 10) 50.3 ± 14.8 y	5 neck-shoulder specific strengthening ex with elastic bands - 30′ supervised training 2 times/w for 10 w - ≥2 d between sessions - 3 × 12 reps (3″/rep) - 1′ pause between ex. - Loads that allowed 12 reps, ending at or near to fatigue. When 17 reps, load progressively ↑	Nordic walking - 30′ supervised training 2 times/w for 10 w - ≥ 2 d between sessions - Moderate intensity. Progressively ↑ (Borg 6–20 scale) - Nordic walking poles: individually adjusted REF group - No physical act	Pain: - Pain intensity (last 5 days’ mean) (VAS1) ~ baseline ~ post-intervention (10 w) ~ 10 w follow-up	Short-term effects (post-intervention): VAS 1: - ↓ SI and NSI; = REF - ΔSI = ΔNSI = ΔREF Long-term effects (follow-up): VAS1: - ↓ SI? (p = 0.058) and NSI; =REF - ΔSI = ΔNSI = ΔREF

Abbreviations: ′, minute/s; ″, second/s; ↑, increased/higher; ↓, decreased/lower; =, no change; ♂, male subjects; ♀, female subjects; ACT, activity/ies; D, day/s; EX, exercise/s; ITT, intention to treat analysis; M, month/s; n, number of subjects; NRS, numerical rating scale; NSI, non-specific intervention; PD, pain drawings; REF, reference group; REP/S, repetition/s; RM, repetition maximum; SI, specific intervention; VAS, visual analogical scale; W, week/s; Y, years.