1 Introduction
2 Methods
Abbreviation | In full |
---|---|
RMSE | Root mean squared error |
T1 | First thoracic vertebrae |
L1 | First lumbar vertebrae |
S1 | First sacral vertebrae |
BFI | Back-foot impact |
FFI | Front-foot impact |
SCR | Shoulder counter-rotation |
GRF | Ground reaction force |
ICC | Intraclass correlation coefficient |
SEM | Standard error of measurement |
MDC | Minimal detectable change |
CMC | Coefficient of multiple correlation |
RMSEP | Root mean square error of prediction |
ROM | Range of motion |
2.1 Participants
2.2 Instrumentation
2.2.1 Inertial sensor system—reliability
2.2.2 Vicon and force plate—validity
2.3 Procedure
2.4 Data processing
2.4.1 Inertial sensor system—tibia
2.4.2 Inertial sensor system—spinal kinematics
2.4.3 Ground reaction force from force plate for validity testing
2.4.4 Spinal kinematics from Vicon for validity testing
2.5 Statistical analysis
2.5.1 Reliability
2.5.2 Validity
3 Results
3.1 Inertial sensor system reliability—tibial accelerations
Back-foot impact | Front-foot impact | |||||||
---|---|---|---|---|---|---|---|---|
Mean (± SD) | ICC | SEM | MDC | Mean (± SD) | ICC | SEM | MDC | |
Tibial acceleration | ||||||||
Peak tibial acc x (g) | 12.42 (5.57) | 0.95 | 1.22 | 3.38 | 25.91 (11.31) | 0.97 | 1.96 | 5.43 |
Peak tibial acc y (g) | 4.29 (3.7) | 0.93 | 1.01 | 2.80 | 12.42 (8.21) | 0.93 | 2.19 | 6.07 |
Peak tibial acc z (g) | 15.85 (8.76) | 0.96 | 1.80 | 4.99 | 20.31 (11.91) | 0.95 | 2.79 | 7.73 |
Resultant tibial acc (g) | 20.11 (7.80) | 0.97 | 1.42 | 3.94 | 35.17 (15.26) | 0.95 | 3.31 | 9.17 |
Time-to-peak tibial acc x (ms) | 25.47 (11.10) | 0.73 | 5.78 | 16.02 | 20.92 (10.39) | 0.84 | 4.10 | 11.36 |
Time-to-peak resultant tibial acc (ms) | 54.59 (21.80) | 0.90 | 7.30 | 20.23 | 58.29 (13.48) | 0.53 | 9.24 | 25.61 |
3.2 Inertial sensor system reliability—spinal kinematics
ICC | SEM (°) | MDC (°) | CMC | RMSE (°) | |
---|---|---|---|---|---|
Shoulder counter-rotation | 0.72 | 2.66 | 7.37 | ||
Lumbar flexion | 0.93 | 4.02 | 11.14 | 0.63 | 3.93 |
Lumbar lateral flexion | 0.64 | 4.46 | 12.36 | 0.71 | 2.92 |
Lumbar rotation | 0.67 | 4.82 | 13.36 | 0.70 | 4.32 |
3.3 Inertial sensor system validity—GRF
GRF variable | Mean (± SD) | Accelerometer variable | Mean (± SD) | r |
---|---|---|---|---|
Back-foot impact | ||||
Vertical peak GRF (N) | 1738.4 (391.2) | Along-tibial peak acceleration (g) | 14.1 (6.6) | 0.974* |
Anterior–posterior peak GRF (N) | 845.8 (138.1) | Anterior–posterior peak acceleration (g) | 11.7 (6.4) | 0.977* |
Mediolateral peak GRF (N) | 254.2 (150.8) | Mediolateral peak acceleration (g) | 3.5 (3.2) | 0.966* |
Resultant peak GRF (N) | 1875.5 (379.8) | Resultant peak acceleration (g) | 20.4 (9.4) | 0.968* |
Time-to-peak vertical GRF (ms) | 30.4 (16.8) | Time-to-peak along-tibial acceleration (ms) | 25.8 (8.5) | 0.979* |
Time-to-peak resultant GRF (ms) | 34.5 (15.4) | Time-to-peak resultant acceleration (ms) | 22.4 (9.4) | 0.767 |
Front-foot impact | ||||
Vertical peak GRF (N) | 3072 (921.9) | Along-tibial peak acceleration (g) | 30.9 (14.4) | 0.871* |
Anterior–posterior peak GRF (N) | 604.6 (587.3) | Anterior–posterior peak acceleration (g) | 23.5 (8.4) | 0.860* |
Mediolateral peak GRF (N) | 405.2 (388.0) | Mediolateral peak acceleration (g) | 16.7 (8.4) | 0.878* |
Resultant peak GRF (N) | 3206.7 (965.1) | Resultant peak acceleration (g) | 46.4 (20.8) | 0.946* |
Time-to-peak vertical GRF (ms) | 15.7 (10.1) | Time-to-peak along-tibial acceleration (ms) | 18.2 (3.2) | 0.772 |
Time-to-peak resultant GRF (ms) | 15.8 (10.1) | Time-to-peak resultant acceleration (ms) | 16.6 (2.8) | 0.640 |
3.4 Inertial sensor system validity—spinal kinematics
Variable | Optoelectronic (° ± SD) | IMU (° ± SD) | r | Mean bias (°) | RMSEP (°) |
---|---|---|---|---|---|
Shoulder counter-rotation | 24.9 (7.7) | 24.0 (7.7) | 0.948* | − 0.9 | 0.3 |
Lumbar flexion at BFI | 5.7 (5.6) | 7.5 (4.7) | 0.986* | 1.9 | 0.5 |
Lumbar lateral flexion at BFI | 5.8 (2.1) | 9.8 (6.6) | 0.949* | 4.0 | 1.2 |
Lumbar Rotation at BFI | 10.3 (6.4) | 12.1 (9.9) | 0.612 | 1.8 | 0.5 |
Lumbar flexion at FFI | 13.6 (8.8) | 17.3 (5.0) | 0.958* | 3.6 | 1.1 |
Lumbar lateral flexion at FFI | 10.8 (10.9) | 13.9 (7.2) | 0.954* | 3.2 | 0.9 |
Lumbar rotation at FFI | 21.2 (7.5) | 16.1 (7.3) | 0.846* | − 5.1 | 1.5 |
4 Discussion
4.1 Tibial acceleration
4.2 Spinal kinematics
Authors | Participants | Spinal segment analysed | Bowling phase analysed | Flexion (°) | Extension (°) | Left lateral flexion (°) | Left rotation (°) |
---|---|---|---|---|---|---|---|
Current Study | 35 | S1-L1 | BFI-FFI | 21 ± 8 | 14 ± 14 | 20 ± 8 | 14 ± 7 |
Bayne et al. 2016 | 13 12 | L5-L1 | FFC-BR | 20 ± 4 21 ± 5 | 11 ± 4 12 ± 3 | 4 ± 2 5 ± 2 | |
Crewe et al. 2013 | 13 18 8 | S1-L1 | FFI-BR | 10 ± 4 12 ± 3 11 ± 3 | |||
Stuelcken et al. 2010 | 14 12 | S1-T1 | BFI-BR | 27 ± 12 29 ± 10 | 14 ± 9 13 ± 9 | 42 ± 6 38 ± 6 | 26 ± 6 27 ± 6 |
Ferdinands et al. 2009 | 21 | S2-T10 | BFI-FFI | 38 ± 8 | 6 ± 2 | 16 ± 11 | 19 ± 2 |
Ranson et al. 2009 | 14 | S1-T10 | BFI-FFI | 0 ± 7 | 34 ± 7 | 29 ± 9 | |
Ranson et al. 2008 | 50 | S1-T10 | BFI-BR | 9 ± 6 | 34 ± 7 | 32 ± 8 | |
Burnett et al. 1998 | 20 | S2-L1 | BFI-FFI | 48 | 10 | 30 | 11 |