Force sensing tandem treadmill

Participants representative of a military recruit population ( 23) completed a 10-wk load carriage-specific physical training program. Lower-body strength, local muscular endurance, and cardiorespiratory endurance were measured before and after a 10-wk training intervention, with perceptual and HR responses assessed during loaded marching task. The load carriage marching task was equivalent to the Australian Army minimum physical employment standards for incumbents ( 23) and was conducted on a force-instrumented treadmill (AMTI force-sensing tandem treadmill, Watertown, MA). A short familiarization session was conducted within the week before the load carriage task, which required participants to walk for 5 min on a treadmill at 5.5 km•h -1 wearing a 23-kg weighted vest. Weight was distributed evenly between the front and back of the torso-borne vest (IronEdge; Power Vest).

Participants in the gait retraining group received a 2-week gait retraining for landing stiffness modulation according to the protocol established in a previous study. 12 (link) In brief, they participated in eight sessions of gait modification over two weeks (four sessions per week). During the training, participants were asked to run at a self-selected speed on an instrumented treadmill (AMTI force sensing tandem treadmill, Watertown, MA, USA).
Visual biofeedback in the form of vertical ground reaction force signal from the treadmill was displayed on the monitor in front. Participants were asked to "run softer" so that the amplitude of vertical impact peak would be reduced or even diminished (Figure 1). The training time was gradually increased from 15 minutes to 30 minutes over the eight sessions and visual feedback was progressively removed in the last four sessions (Figure 2). The participants were then advised to maintain their new gait pattern during their daily living or regular running practice after the training. Similar to the gait retraining group, participants in the control group were invited to the laboratory for eight times in two weeks. They were asked to run on an instrumented treadmill at a self-pace speed but no feedback of their running biomechanics was provided. The running time was identical to the protocol in the gait retraining group.

To perform the warm-up and control intensity a treadmill AMTI Force sensing tandem treadmill (AMTI, Watertown, MA, USA) and RS polar RS 100 (Polar Electro, Kempele, Finland) was used.
Bar velocity was measured using a linear transducer sampling at 1000 Hz (T-Force System, Ergotech, Murcia, Spain) connected to a 16-bit analogue to digital converter (Biopac MP100 Systems Santa Barbara, CA, USA).
The T-force System was interfaced with a personal computer to automatically calculate the relevant kinematic and kinetic parameters for every repetition, providing real-time feedback and data storage. To standardise the starting joint configurations in each repetition, the knee joint angle was measured using an electrogoniometer (Penny & Gilles, Biometrics Ltd., Blackwood Ltd., London UK). The Full Squat and Half Squat exercises were conducted using a Smith machine (Multipower Fitness Line, Peroga, Spain), while for the Leg Press a custom-built 45º leg press machine was used. ******Insert Figure 1 near hereinstrumentation*****