Summary of final variables considered in the regression models
| Description | Abbreviation | Values |
|---|---|---|
| Maximum pain (VAS) at the time of the injury reported by the athlete (0–10) | MaxP | 6.9 (6.50 to 7.31), 7.00 (3.00–10.00) (85) |
| Strength of the injured (Inj) or uninjured (Uninj) leg in kg using a hand held dynamometer in the ‘Outer Range’ position | OuterInj/OuterUninj | 14.4 (12.71 to 16.13), 11.90 (2.40–36.90) (80) |
| Strength of the injured (Inj) or uninjured (Uninj) leg in kg using a hand held dynamometer in the ‘Mid Range’ position | MidInj/MidUninj | 13.4 (11.50 to 15.27), 11.20 (2.00–35.20) (84) |
| Strength of the injured (Inj) or uninjured (Uninj) leg in kg using a hand held dynamometer in the ‘Outer Range’ position | InnerInj/InnerUinj | 12.6 (11.45 to 13.78), 12.20 (3.00–26.00) (85) |
| Athlete reports no pain during ‘outer range’ strength testing with HHD (yes/no) | PainlessOuterInj | Yes=58, No=15 |
| Athlete reports no pain during ‘mid range’ strength testing with HHD (yes/no) | PainlessMidInj | Yes=51, No=25 |
| Athlete reports no pain during ‘inner range’ strength testing with HHD (yes/no) | PainlessInnerInj | Yes=43, No=33 |
| Strength of the injured leg when tested in the ‘outer range’ position expressed as a percentage of the uninjured leg in the same position | Outer% | 0.5 (0.45 to 0.57), 0.43 (0.08–1.13) |
| Strength of the injured leg when tested in the ‘outer range’ position expressed as a percentage of the uninjured leg in the same position | Mid% | 0.5 (0.45 to 0.57), 0.43 (0.09–1.21) |
| Strength of the injured leg when tested in the ‘outer range’ position expressed as a percentage of the uninjured leg in the same position | Inner% | 0.6 (0.58 to 0.69), 0.63 (0.12–1.47) |
| Athlete plays football | SportFootball | N=64 |
| Athlete plays basketball | SportBasketball | N=4 |
| Athlete plays volleyball | SportVolleyball | N=1 |
| Athlete plays handball | SportHandball | N=3 |
| Track and field athlete | SportAthletics | N=4 |
| Athlete plays futsal | SportFutsal | N=5 |
| Athlete plays a different sport | SportOther | N=5 |
| Hamstring flexibility test: passive knee extension with the hip in 90° of flexion, supine; Injured/Uninjured leg (°) | PKETInj/ PKETUninj | 56.2 (49.64 to 62.85), 55.00 (−28.00 to 160.00) 83.5 (80.09 to 86.98), 90.00 (40.00–125.00) |
| Hamstring Flexibility test: passive straight leg raise; Injured/Uninjured leg (°) | SLRInj/SLRUninj | 64.3 (59.07 to 69.49), 65.50 (14.00–160.00) 89.5 (85.98 to 93.01), 91.00 (58.00–121.00) |
| Player has had a previous hamstring injury on both legs (compared to no past history, or an injury on one leg only) (yes/no) | PrevHSInjBoth | N=31 (no previous injury=18, one leg only previously injured=34) |
| Per cent of appointments attended of available appointments (maximum 5 days per week) | Attendance% | 0.8 (0.79 to 0.87), 0.89 (0.00–1.00) |
| Peak torque of knee flexion tested at tested at 60°/s, concentrically (N·m) | PTH60c | 112.3 (107.37 to 117.16), 112.00 (61.40–156.10) |
| Angle of peak torque of the quadriceps, tested at 60°/s, concentrically, uninjured leg (°) | APTQ60Uninj | 67.8 (64.86 to 70.80), 70.00 (14.00–89.00) |
| Change in strength of the injured leg, expressed as a percentage of the week 1 strength value of that leg, tested in ‘inner range’ | Wk1▵InnerInj | 10.8 (9.41 to 12.10), 10.54 (−4.33 to 24.98) |
| Change in strength of the injured leg, expressed as a percentage of the week 1 strength value of that leg, tested in ‘mid range’ | Wk1▵MidInj | 11.1 (8.99 to 13.22), 9.59 (−3.62 to 34.01) |
| Change in strength of the injured leg, expressed as a percentage of the week 1 strength value of that leg, tested in ‘outer range’ | Wk1▵OuterInj | 12.3 (10.38 to 14.25), 9.69 (−4.68 to 35.70) |
| Days until player reports pain free walking (maximum 7) | TimeWalk | 2.9 (2.31 to 3.43), 2.00 (0.00–10.00) |
| Athlete is unable to painlessly perform 3 repetitions of a single leg bridge exercise painlessly on the injured leg (yes/no) | SLBridgePain | N=29 (44 athletes able to perform painlessly) |
| Number of days delay from injury to starting physiotherapy | DelayRx | 3.3 (3.03 to 3.66), 3.00 (0.00–8.00) |
| Volume of oedema within the injured muscle group as seen on MRI, measured in cm3 | VolOedema | 73.4 (53.93 to 92.86), 31.87 (0.00–409.98) |
Values column represents mean (95% CI), median (minimum–maximum) (N) except where the data are simple counts.
HHD, hand held dynamometry; MaxP, maximum pain at the time of injury; PTH, peak torque hamstrings; RTS: return to sports; SLR, straight leg raise flexibility; TR/TE, relaxation time/echo time; VAS, visual analogue scale.