Table 2 Population characteristics and procedural details. Voluntary muscle activation
Study and country of origin | Subject details (age in years; height in cm) | Asymptomatic control details (age in years; height in cm) | Task | Electrode type; sampling rate; signal processing | EMG onset determination method | AKP during test |
|---|---|---|---|---|---|---|
Boling et al [15] USA | No start/completion: 14/14 M/F: 5/9 Age: 24 ± 6 Height: 167.5 ± 10.1 Profile: University population and local community. Symptom Duration: Min 2 months | No start – completion: 14/14 M/F: 5/9 Age: 23 ± 2 Height: 170.9 ± 7.3 Profile: University population. | Stance phase asc/desc stair (20 cm step height) | Surface Electrodes; SR 1000 Hz; FWR & LPF 50 Hz | Point at which signal exceeded mean + 3 SD of baseline level for minimum of 25 ms | NS |
Brindle et al [21] USA | No: 16/16 M/F: 4/12 Age: range 18–35 Height: NS Profile: Student population and local community. Symptom Duration: Min 2 months | No: 12/12 M/F: 5/7 Age: "Age matched" Height: NS Profile: NS | Stance phase asc/desc stairs (18 cm step height, 22 cm depth) | Surface Electrodes; SR 960 Hz; FWR & LPF 15 Hz | Point at which mean voltage of a moving 25 ms window exceeded mean + 5 SD of baseline level | Yes. 4.4 ± 3.0 during asc., 4.25 ± 1.8 during desc (on 10 cm VAS) |
Cowan et al [5] Australia | No: 33/33 M/F: 11/22 Age: 27.0 ± 8.1 Height: 171.1 ± 9.3 Profile: NS Symptom Duration: 42.2 months ± 49.9 (1–144) | No: 33/33 M/F: 13/20 Age: 23.6.0 ± 4.9 Height: 169.8 ± 11.9 Profile: University of Melbourne School of Physiotherapy. | Stance phase asc/desc stairs (20 cm step height) | Surface Electrodes; SR 1000 Hz; FWR & LPF 50 Hz | Point at which signal exceeded mean + 3 SD of baseline level for minimum of 25 ms | Yes 2.6 ± 2 (on 0–10 cm VAS) |
Cowan et al [16] Australia | No: 10/10 M/F: 3/7 Age: 22.7 ± 8.0 Height: 167.1 ± 9.6 Profile: N/S Symptom duration: > 1 month | No: 12/12 M/F: 4/8 Age: 19.5 ± 1.4 Height: 170.9 ± 10.5 Profile: Students – School of Physiotherapy | Stance phase asc/desc stairs (20 cm step height) | Surface Electrodes; SR 1000 Hz; FWR & LPF 50 Hz | Point at which signal exceeded mean + 3 SD of baseline level for minimum of 25 ms | Yes 3.5 ± 0.5 (on 0–10 cm VAS) |
Cowan et al [20] Australia | No: 37/37 M/F: 14/23 Age: 28.5 ± 7.3 Height: 170.7 ± 8.9 Profile: N/S Symptom duration: 10.9 months ± 22.3 | No: 37/37 M/F: 14/23 Age: 24.4 ± 5.8 Height: 171.9 ± 12 Profile: Students – School of Physiotherapy | Reaction time to visual instruction – 2 random tasks: rocking back on heels or rising on toes | Surface Electrodes; SR 1000 Hz; FWR & LPF 50 Hz | Point at which signal exceeded mean + 3 SD of baseline level for minimum of 25 ms. | No |
Crossley et al [14] Australia | No: 48/47 M/F: 17/31 Age: 28.5 ± 8 Height: 170 ± 9 Profile: N/S Symptom duration: 8 months ± 8 | No: 18/18 M/F: 9/9 Age: 35.5 ± 5 Height: 172 ± 12 Profile: Students University of Melbourne | Stance phase asc/desc stair (20 cm step height) | Surface Electrodes; SR 1000 Hz; FWR & LPF 50 Hz | Point at which signal exceeded mean + 3 SD of baseline level for minimum of 25 ms. | Yes, 2.5 ± 2.0 (0–10 VAS) |
Earl et al [17] USA | No: 16/15 M/F: 3/13 Age: 21.5 ± 4.2 Height: 165.3 ± 10.2 Profile: Recreational athletes. Physical therapy and Sports Medicine Clinics Symptom duration: 9.3 weeks, (1–24 weeks) | No: 16/15 M/F: 3/13 Age: 21.1 ± 11.5 Height: 165.6 ± 11.5 Profile: Recreational athletes matched on gender, age, height, weight and exercise per week. | Lateral step down off 20.3 cm block | Surface Electrodes; SR 1200 Hz; processed with RMS 10 data point window | Point at which signal exceeded mean + 3 SD of baseline level for minimum of 25 ms. | NS |
Karst and Willett [30] USA | No: 24/24 M/F: 6/18 Age: 28.3 ± 7.6 Height: 172.0 ± 10.9 Profile: NS Symptom duration: At least one year | No: 24/24 M/F: 8/16 Age: 28.8 ± 7.9 Height: 173.5 ± 8.2 Profile: NS | 1) See table below 2) NWB active knee extension 3) WB knee extension – lateral step up onto 8 cm block | Surface Electrodes; SR 4000 Hz; unclear what smoothing process used (e.g. LPF or RMS) | Point at which signal exceeded mean + 1 SD of baseline level | NS |
McClinton et al [22] USA | No: 20/20 M/F: 11/9 Age: 29.5 ± 10.0 Height : 173 ± 10 Profile: NS Symptom duration: NS | No: 20/20 M/F: 10/10 Age: 25.4 ± 3.1 Height: 172 ± 12 Profile: NS | Stance phase asc stairs (8, 14, 20, 26, 32 cm step height) | Surface Electrodes; SR 960 Hz; FWR & LPF 6 Hz | Point at which signal exceeded + 2SD of baseline level for 20 ms. | Yes 1.7 ± 0.3 (14 cm step) to 3.1 ± 0.5 (32 cm step) (0–10 VAS) |
Morrish and Woledge [46] UK | No: 49/49 M/F: 16/33 Age: 20–37 (median 26) Height: NS Symptom duration: 6–120 months. Profile: NS | No: 20/20 M/F: 7/13 Age: 20–33 (median 25) Height-not stated. Profile: University staff and students who were non-or recreational athletes. | Isometric knee extension in sitting, with knee in 20 degrees flexion. | Surface Electrodes; SR not stated; FWR & integrat'n over 100 ms intervals | Actual onset not determined. Level of EMG signal over time relative to quadriceps force generation (termed lag factor). | NS. |
Owings et al [19] USA | No: 20/20 M/F: 8/12 Age: F33.7 ± 6.9; M29.1 ± 10.7 Height: F1.65 ± 0.06; M1.77 ± 0.08 Profile: NS Symptom Duration: NS | No: 14/14 M/F: 10/4 Age: F22.3 ± 1.6; M24.5 ± 2.3 Height: F1.63 ± 0.07, M1.81 ± 0.06 Profile: NS | Isokinetic knee flexion/extension in sitting. Hip and trunk angle approx 100 degrees. Control 60 degree/sec, Subjects 15 deg/sec. | Surface Electrodes; SR 1000 Hz; raw signal used for onset | Point at which signal surpassed resting value | NS but did need to change method due to pain. |