The field of biomechanics is often challenged with the tasks of increasing performance and decreasing injury in sport. In rowing, sport biomechanists have often investigated both performance variables and injury mechanisms, yet there has been little effort, or at least published work, towards either task in para-rowing, an area of rowing geared towards including individuals with disability in sport. The prevalence of injury and lower back pain in able bodied rowing athletes is high and has been relatively well investigated (Bull and McGregor, 2000;​ Caldwell et al, 2003;​ Hosea et al, 1989;​2012;​ Howell et al, 1984;​ Munro and Yanai, 2000;​ Reid and McNair, 2000;​ Teitz et al, 2002;​ 2003;​ Wilson et al, 2012), yet to date no literature has investigated potential mechanisms of injury in para-rowers. The purpose of this research was twofold:​ One, validate the use of a commercially available software program, Classic JACK, typically used for analysis of occupational tasks to analyze the biomechanics of the para-rowing strokes. Two, identify the kinematics and kinetics of the para-rowing strokes, and further investigate proposed mechanisms of injury from the able bodied literature.

The computer simulation software Classic JACK version 6.2 was used to investigate a set of indoor rowing ergometer tasks in the Legs Trunk and Arms (LTA), Trunk and Arms (TA), and arms and shoulders (AS) para-rowing setups. Kinematic data was recorded using a set of 41 virtual markers, adhered to participants at key anatomical landmarks;​ as required by the Classic JACK motion capture tool kit (Appendix A). The connection between the ergometer handle and chain was instrumented with an S type strain gauge to obtain kinetic pull force. The kinematic and kinetic data was then exported into the JACK software environment to animate a virtual rower that was anthropometrically matched the study participant. JACK’S TAT loader analysis tool was used to apply the kinetic pull force at the hands of the virtual rower and to calculate musculoskeletal compressive and shear forces at the lower back (L4/L5) throughout the drive phase of the stroke.

The JACK software was successfully used to measure compressive and shear forces at the lower back for participants completing an indoor ergometer rowing task. To our knowledge this is the first use of the JACK software in a sport application to investigate both kinetic and kinematic information. Peak compressive forces acting on the lumbar spine obtained in this study were 6.7 times body weight (4974 N) for the LTA setup, similar those previously reported 6.8 -7 times bodyweight previously reported in the able bodied literature (Hosea et al, 2012;​ Munro and Yanai, 2000). Peak compressive force in the TA (4035 N) and AS (2634 N) para-setups are the first para-rowing biomechanical data to be reported in the literature, and represent necessary information in the discussion of upper body injury for this population. The TAT loader reported shear forces for male (2798 N) and female (1636 N) participants that are greater than previously reported in the literature (Hosea et al, 2012;​ Morris et al, 2000).

Able bodied university aged varsity rowers were recruited (n=17, 9 male, 8 female) to participate in a study examining the biomechanics of the para-rowing setups. Subjects performed three trials of 10 maximal effort strokes while attempting to maintain their best technique for each setup (nine trials total). Participants attempted to maintain stroke rates of 24, 30, and 36 strokes per minute for the LTA, TA and AS setups respectively. Drag resistance units (DU) were adapted, off of the established recommendations for para-rowing setups (Lewis, K., 2011), for gender and weight class (Appendix B). The kinematic and kinetic data was then transferred into the Classic JACK virtual environment as described above.

The kinematics and handle force kinetics of the LTA stroke were found to be consistent with previously reported data in the able bodied literature. Lumbar flexion at the catch, extension at the finish, and total range of motion were greater than previously reported in the literature, which may be a representation of 1) the level of skill of the participants or 2) participants attempting to row maximally and adjusting their technique to achieve performance through increasing stroke length and force application. Additionally, rowers utilized greater ranges of motions at specific joints in the TA and AS setups in comparison to the LTA setup. In the TA setup, lumbar flexion, extension, and total range of motion were significantly greater than that of LTA rowing. Similarly, the amount of elbow flexion and shoulder abduction at the finish increased by setup LTA

Peak compressive and shear forces exceeded the NIOSH single lift recommendation limits of 3400N and 500N, respectively, for occupational tasks, but are lower than other maximal efforts in sports such as power lifting, gymnastics, and football (Bruggemann, G.P., 2000;​ Cholewicki et al, 1991;​ Gatt et al, 1997;​ Granhed et al, 1987;​ Lander et al 1990). Studies investigating compressive force in longer duration ergometer rowing tasks (2000 meter race simulation) have documented much lower average peak forces, which is likely a representation of decreased force output over the longer duration of the task (Morris et al, 2000). Thus, compressive and shear forces reported in this study represent near maximal values for rowers in the para-rowing setups and not the values that would be typical during regular exercise on-the-water or on the ergometer.

Investigations of injury mechanisms in a repetitive motion sport such as rowing, that are not related to single incident traumatic injury, is likely multi-factorial, difficult to interpret, and demands careful consideration. For para-rowers, such an investigation becomes even more dubious in nature owing to each individual’s disability, needs, and history of participation in sport. Yet this study provides several strong considerations for researchers, coaches, and athletes in an effort to promote participation in sport and mitigate injury. First, rather than injury causative, we support the proposal that compressive forces during rowing are likely a good promoter of a healthy spine and joints (Hase et al, 2004;​ Morris et al, 2000), when adequate recovery is permitted and long duration workouts are completed while being mindful of the effects of fatigue. Second, the postural mechanics observed during the para-rowing trials of this study represent ranges of motion at the lumbar spine, shoulder, and elbow that may place the para-athlete at risk of overuse injury. We recommend that coaches pay particular attention to promoting technique that does not maximize stroke length by placing the participant’s body in a position where it may be susceptible to injury, but rather in positions where the athlete is best able to tolerate the mechanical demands of rowing.

This research provides the firsts, to our knowledge, of both the application of the Classic JACK software for analysis of sport and the biomechanics of the para-rowing strokes. It is the hope of the authors of this work, that the information contained be used to promote the participation of athletes with disability in sport and further the investigation of injury mechanisms in the rowing community of researchers, coaches and athletes.