Gymnastik- och idrottshögskolan, GIH

In sit-skiing, propulsion is generated by the upper-extremities and trunk. We examined if terrain incline and class affected the speed, trunk range of motion, and cycle kinematics of sit-skiers during competitive distance events. Thirty-six elite Para-Nordic sit-skiers were equipped with integrated IMU- and GNSS-sensors at the 2022 and 2023 World Championships, and five individual races were analysed at each event. Relationships between speed, trunk range of motion, cycle length and cycle rate and "incline" and "class" were modelled using mixed-effects models. The classes showed similar adaptations to changing incline, with decreased speed and cycle length and relatively constant range of motion and cycle rate. Compared to the LW12 class, the LW10.5 class had a lower speed (p = 0.004), trunk range of motion (p = 0.005) and cycle length (p = 0.049) at the 2022 event and lower range of motion (p = 0.017) and higher cycle rate (p = 0.020) at the 2023 event. There were considerable overlaps between the classes in all variables, which highlights that despite a relatively large number of measurements, this study was likely statistically underpowered for the between-class comparisons. Overall, this study suggests that while some differences exist between the LW12 and LW10.5 classes, between-class differences may be smaller than the differences between individual athletes.

Inertial measurement units can provide biomechanical insights into tasks performed in the laboratory and in the field and have yielded valuable information for practitioners and researchers alike within several sports. However, for data from such sensors to be interpretable, it requires considerable processing. Although the literature using sensor technology is substantial, description of the data processing methodologies often lacks sufficient detail to allow for replication and therefore limits applications in the field and research. To address these limitations in the existing literature, we present a step-by-step approach to process the data from a single inertial measurement unit aggregated with global navigation satellite systems data for performance analysis of the skiing component of an elite-level sitting para-biathlon competition. Since the degree of trunk motion is important for sit-ski performance, our analysis extends on previously reported frameworks and aims at adding new quantifications of trunk range of motion in addition to speed, cycle rate, and cycle length. This new framework will allow analysis of how all these important variables changes throughout the racecourse. In addition, we discuss the rationale behind the design of the method along with its limitations and underline processing options that can be adapted to suit a variety of research questions or analytical approaches, which may include other activities or measurement devices. With this, we encourage other researchers to report their methodology in detail and, by extension, contribute to facilitating the process of replicating and developing existing methods for both academia and practice.

Para cross-country (XC) skiers compete in race courses with different terrains (uphill, downhill, and undulated) across several classes in three categories (visually, standing, and sitting impaired). The objectives were to investigate (1) the distribution of distance and relative race time spent in different terrains (%RT(Terr)) across different races, and (2) the association of class with %RT(Terr) while adjusting for sex and final rank. Sixty-eight Para XC skiers were tracked with GNSS sensors during middle- and long-distance races at two World Championships. Linear mixed models were used to investigate the association of class with %RT(Terr) while adjusting for sex and final rank. The relative distance covered in each terrain (uphill: 17%-42%, downhill: 27%-46%, and undulated: 12%-56%) and corresponding %RT(Terr) (uphill: 20%-58%, downhill: 16%-30%, and undulated: 12%-57%) varied across races. Nevertheless, individual %RT(Terr) was relatively consistent among the Para cross-country skiers within each race. There was no significant effect of class on %RT(Terr) for sitting and standing skiers, indicating that the differences between classes are similar or smaller than those between individual skiers within a class. In contrast, there was a significant effect of class on %RT(Terr) for the visually impaired skiers (p < 0.019). Furthermore, lower ranked skiers spent approximately 0.1-0.25%pt more time in the uphill terrain per rank (p < 0.001 for all categories) and approximately 0.05-0.25%pt less time in the downhill terrain per rank (p < 0.01). Finally, women skiers spent significantly more of their %RT(Terr) in the uphill terrain ( approximately 1.3-2.3%pt, p < 0.04) and less in the downhill terrain ( approximately 1.0-2%pt, p < 0.01). Given the small sample size within most classes, our findings need to be interpreted with caution.

OBJECTIVE: This study investigated whether the origin (acquired or congenital) and type of impairment affect the participation and likelihood of winning a medal in different sports at the Paralympic Games. DESIGN: We analyzed competition data and athlete biographies web scraped from the International Paralympic Committee's website ( www.Paralympic.org ). RESULTS: In some sports, athletes with one origin or type of impairment were overrepresented. For example, 76% of Para-snowboarders had an acquired impairment. Furthermore, mixed effects logistic regression analyses showed that the origin of impairment had no effect on the likelihood of winning a medal in most sports. However, athletes with a congenital impairment had a significantly higher likelihood of winning a medal compared to those with an acquired impairment in Para-athletics, Para-alpine skiing, and Para-biathlon (odds ratio: 1.71, P < 0.01, odds ratio: 3.69, P = 0.002, and odds ratio: 3.70, P = 0.016, respectively). Athletes with a given origin-type of impairment combination also may have an advantage or disadvantage in some sports. For example, athletes with an acquired spinal cord injury win proportionally fewer medals in Para-powerlifting. CONCLUSIONS: Understanding potential effects of the origin and type of impairment on participation and medaling chances in Paralympic sports can help shape the development of Para-sports and support talent identification.

This study assessed the biomechanical effects of restricted thorax motion during fixed-seat ergometer rowing. Eleven able-bodied participants performed 2 bouts of 4 minutes of submaximal rowing on a custom-made fixed seat. First, the participants were strapped at the waist, allowing thorax motion (“Free thorax”), then strapped around the chest, preventing thorax motion (“Fixed thorax”). Kinematic analysis and force exerted on the ergometer chain were recorded. The “Fixed thorax” setup had lower total power output (p=0.011, Cohen’s d=1.61), total average joint power (p=0.006, Cohen’s D d=1.32) and VO2 (p=0.005, Cohen’s d=2.00). No differences existed in the elbow and shoulder power between the setups. The results suggest that restricting the thorax has a negative effect on submaximal effort rowing performance, which could have implications for competitions.

Introduction: This study (i) examined Norwegian and Swedish sports coaches' employment, practices, and beliefs during the first wave of the COVID-19 pandemic, (ii) compared these aspects between coaches in Norway and Sweden, two countries with clearly different movement restrictions strategies in this period.

Methods: An online survey was distributed to coaches via email and social media. The survey was open between June and August 2020. In total, 348 coaches responded, 141 from Norway, and 207 from Sweden.

Results: Among responders, 2% had lost their job due to the pandemic, 17% had been furloughed, 28% worked from home office, and 39% worked as usual. Norwegian coaches were more likely to work from home (48% vs. 15%, p < .001), while Swedish coaches were more likely to work as usual (60% vs. 9%, p < .001). Coaches in both countries communicated less frequently with their athletes (p < .001) and had less in-person communication (p < .001) compared to pre-Covid levels. Larger declines existed among Norwegian coaches regarding communication frequency (p < .001) and in-person communication (p < .001). Video calls and phone calls usage increased (p < .001 and p = .009 respectively). We recorded low levels of concern among coaches about the effects of the pandemic on their relationship with their athletes. There were considerable levels of concern about athletes’ maintaining their motivation to train (Norway: 43.3%, Sweden: 50.7%), and low levels of concern about the coaches’ relationships with their athletes (Norway: 14.1%, Sweden: 17.8%).

Discussion: Overall, this study showed the imposed movement restrictions had several negative consequences for the employment and work practices of sports coaches in Norway and Sweden. However, it also highlighted that coaches were able to adapt their work practices to the constraints and were able to maintain relationships with their athletes. The consequences raised in this paper can act as a guide during possible future lockdowns.

OBJECTIVE: This study established the age-related performance trajectories in Para powerlifters, thereby presenting valuable information for athlete development. DESIGN: Data on athlete date of birth, body mass, and weight lifted in competition were analyzed for 2079 athletes between 1994 and 2019. RESULTS: Age-related performance trajectories showed that men and women lift their heaviest weights in competition at 36 and 41 yrs of age, respectively. This correspond to the mean age of competitors in the heaviest bodyweight categories at elite competitions (men 36 yrs, women 43 yrs), who were older than competitors in lighter bodyweight categories. It is possible that para powerlifters "move up" bodyweight categories as they get older and before lifting their heaviest weights in competition. High-performing athletes lifted their heaviest weight in competition 2.6 yrs earlier than lower performing peers, and the best performances in most bodyweight categories were achieved by athletes between 31 and 35 yrs of age. CONCLUSIONS: These results suggest that para powerlifters should reach their peak performance in their early to mid-30s and before age-related changes to neural and hormonal processes impact muscular strength. This information can help coaches and athletes evaluate their strategies for achieving success in para powerlifting.

This study investigated micro-pacing strategies during sit para-biathlon. Six elite sit para-biathletes wore a positioning system device during the world-championships in three different competition formats (Sprint, Middle-distance, and Long-distance). Total Skiing Time (TST), penalty-time, shooting-time, and Total Race Time (TRT) were analysed. One-way analyses of variance were used to compare the relative contributions of TST, penalty-time, and shooting-time to TRT across the three race formats. Statistical parametric mapping (SPM) was used to determine the course positions (clusters) where instantaneous skiing speed was significantly associated with TST. The contribution of TST to TRT was lower for the Long-distance (80 & PLUSMN; 6%) compared to the Sprint (86 & PLUSMN; 5%) and Middle-distance (86 & PLUSMN; 3%) races, however this difference was not statistically significant (p > 0.05). The proportional contribution of penalty-time to TRT was significantly greater (p < 0.05) for the Long-distance (13 & PLUSMN; 6%) compared to the Sprint (5 & PLUSMN; 4%) and Middle-distance (4 & PLUSMN; 3%) races. Statistical parametric mapping (SPM) revealed specific clusters where instantaneous skiing speed was significantly associated with TST. For example, over all laps during the Long-distance race, the fastest athlete gained 6.5 s over the slowest athlete in the section with the steepest uphill. Overall, these findings can provide insights into pacing strategies and help para-biathlon coaches and athletes optimise training programmes to improve performance.

BACKGROUND: The clinical examination for laxity has been considered a mainstay in evaluation of the painful knee arthroplasty, especially for the diagnosis of instability. More than 10 mm of anterior-posterior (AP) translation in flexion has been described as important in the diagnosis of flexion instability. The inter-observer reliability of varus/valgus and AP laxity testing has not been tested. METHODS: Ten subjects with prior to total knee arthroplasty (TKA) were examined by 4 fellowship-trained orthopedic knee arthroplasty surgeons. Each surgeon evaluated each subject in random order and was blinded to the results of the other surgeons. Each surgeon performed an anterior drawer test at 30 and 90 degrees of flexion and graded the instability as 0-5 mm, 5-10 mm or >10 mm. Varus-valgus testing was also graded. Motion capture was used during the examination to determine the joint position and estimate joint reaction force during the examination. RESULTS: Inter-rater reliability (IRR) was poor at 30 and 90 degrees for both the subjective rater score and the measured AP laxity in flexion (k = 018-0.22). Varus-valgus testing similarly had poor reliability. Force applied by the rater also had poor IRR. CONCLUSION: Clinical testing of knee laxity after TKA has poor reliability between surgeons using motion analysis. It is unclear if this is from differences in examiner technique or from differences in pain or quadriceps function of the subjects. Instability after TKA should not be diagnosed strictly by clinical testing and should involve a complete clinical assessment of the patient.