# The Effects of a Simulated Duathlon on Trunk Motion: A Sensor Based Approach
## 4 Discussion
### Run Post-Cycling (RunPost)
Although trunk accelerations can and do occur in the mediolateral and anteroposterior directions combined with deviations from the sagittal plane, to maintain trunk control and restrict motion to the sagittal plane, a greater extent of trunk, or core, strength is needed. Running and cycling are characterised by distinct types of upper and lower limb motion and physiological correlates [14; 41] along with both kinetic and kinematical variations [24; 29; 42]. However, caution is required if directing an athlete to assume new running mechanics based only on reducing trunk acceleration, as running is a multifaceted motion that requires metabolic, cardiorespiratory, and neuromuscular considerations. Despite the intricacies involved in running, if the disadvantageous impact of unnecessary trunk acceleration could be reduced, there exists likely opportunities to develop training-based interventions for trunk control when running after cycling. This study does have limitations inherent to this type of field-based study design. Firstly, given the relatively small sample size used for this study (i.e., 10 participants were recruited), this limits the statistical power; therefore, a larger sample would be necessary for a greater interpretation of the results. Secondly, though the participants were asked to retain their customary running and cycling mechanics, when external variables such as headwind (drag) during cycling are considered, it may be that the participants had to modify their trunk, albeit marginally. Here, a small adjustment to the trunk may have influenced participant performance. It is uncertain how the varying components of drag affected the participants' trunk motion and acceleration; this warrants further investigation. This study included both male and female participants. The differences between the sexes in body composition are well proven; therefore, studying running performance and magnitudes of trunk acceleration pre and post a cycling load between male and female athletes in duathlon is warranted. Running and cycling economy, that is, efficiency and effectiveness, is a variable that will likely alter depending on individual factors. Here, participant variability relative to biomechanical factors such as stride rate, stride strength, and cycling pedalling technique are multifactorial measures. Such measures, while out of scope in our study, are determined by training, metabolic, cardiorespiratory, biomechanical, and neuromuscular factors [43]. Finally, we allocated five minutes between each participant commencing the initial 5 km run. A duration of five minutes was selected to allow sufficient time for each participant to self-select their running speed. Despite this, we acknowledge that some participants may have felt a level of competitiveness or the feeling of chasing or being chased by another participants. This was mitigated as best as possible by use of the RPE scale at each 1 km in running to monitor exertion levels. Yet, the contribution of each factor to duathlon performance will likely depend on how technical (i.e., skilled) the movement is. This acknowledges the need for additional research to encourage further insight into the intricacies of the influence of cycling in running performance in duathlon. Our study reported magnitudes of trunk acceleration in running and cycling from an amateur athlete standpoint. This limits the application of our results to the semiprofessional and elite category of duathletes. Future studies should apply a similar protocol using elite athletes instead of amateur level athletes. Arguably, however, both modes of research design (e.g., elite vs. amateur) are necessary to allow further scientific evidence for coaches, athletes, and sports scientists to analyse respective datasets with the aim of improving performance in all disciplines of duathlon. This will permit athletes to prepare more judiciously for multisport events.