What Is Known

Recent studies have described the development and performance trajectories of some Paralympic sports. However, there are scarce articles on Para canoe and none regarding its performance trajectory.

What Is New

This study provides insights into the performance trajectories and characteristics of kayak Para canoe athletes. The results also highlight improvements in race times for male and female athletes across most classes, reduced relative differences in race times between classes, underrepresentation of female athletes, and prevalence of impairments for each class. Coaches can use these valuable findings to track athlete progress, establish achievable performance objectives, and make informed choices in selecting appropriate Para sports.

Para canoe is one of the Para sports eligible for different motor impairments. This adapted sport debuted internationally as an exhibition at the 2009 World Canoe Sprint Championship in Dartmouth, Nova Scotia, Canada, and was introduced as an official Paralympic sport in the Rio de Janeiro 2016 Paralympic Games. Reduced strength, range of motion, or impairment that compromises the lower limbs and trunk are the minimum criteria impairment used as guidance for eligibility for this Para sport.1 Once the participant's eligibility has been confirmed, three batteries of tests are performed, and the athlete will be allocated to one of the following three classes: (1) KL1 (kayak level 1): athletes with greater motor impairment, usually with reduced or no trunk and lower limb strength (e.g., T12 spinal cord injury); (2) KL2 (kayak level 2): athletes with preserved trunk function and reduced or no lower limb strength (e.g., transfemoral bilateral amputations or spinal cord injuries below T12); and (3) KL3 (kayak level 3): athletes with less motor impairment, typically with preserved trunk function and reduced lower limb strength (e.g., unilateral lower limb amputation).1 This evidence-based classification system was developed and accepted by the International Paralympic Committee (IPC) in 2015 to be included in the Paralympic Games to replace the initially adopted classification system from Para rowing. In the Paralympic Games, World Championships, and World Cups, all the Para canoe races are 200 meters long and individual.1 Over the past few years, all classes in this Para sport have consistently achieved race times of less than 55 secs, highlighting the significant speed characteristic of the sport.

In speed sports, performance is multifactorial and dependent on interrelated variables, such as the rate of strength development, muscle power, maximum muscle strength, and anaerobic power.2–4 Muscular strength increases linearly from early childhood; however, it is more pronounced during puberty in boys.5 After puberty, the rate of strength development depends on the training stimulus and eventually decreases with prolonged exposure to training.6 For Para canoe coaches and athletes, it is important to understand how muscle strength changes throughout life due to biological, morphological, and environmental factors, such as growth, maturation, training, and aging. Thus, biological age is considered an important aspect of the development of athletes in all sports and is often associated with peak sports performance.7–11 However, the extent of this association in Para canoe remains unclear. Nevertheless, literature on other Para sports suggests that men generally achieve peak performance at a younger age than women in Para powerlifting12 while in female Para swimmers, faster times are observed during adolescence.13 In Para canoe, the age of peak performance may be similar for both sexes due to the numerous variables involved and the evolution of the sport over time.

Performance trajectories are also influenced by other variables, such as classification, sex, the origin of the impairment, and socioeconomic opportunities and are often considered specific to the nondisabled sport and Para sport.9,10,12–16 Advancements in technology, specifically in the design of canoes and paddles, promote better efficiency and speed. In addition, improvements in training techniques and greater access to resources might have also played significant roles in enhancing performance over the years. The growing number of athletes, particularly those with more severe impairment, may have contributed to a steeper enhancement of performance mainly in lower Para canoe classes and a resulting reduction in the differences in race times between classes.

Studies associating age, classification, and sex with performance in Para sports have shown that wheelchair basketball players,14 Para swimmers,13 Para athletics racing athletes,15 and Para powerlifters12 achieve peak performance later than Olympic athletes for the same nondisabled sports. The start of the athletes' participation in Para sports usually occurs at more advanced ages, mainly due to acquired injuries, which seems to be one of the factors that can explain this discrepancy.12,14,16 Moreover, the lack of depth in sports to facilitate competition for younger athletes or earlier in the pathway, particularly for those with impairments that are congenital or acquired earlier in life, could also contribute to the delayed entry of athletes into Para sports. However, specificities that are not common to Olympic athletes, such as adaptation to equipment, physiological alterations due to the impairments, medical adjustments, classification, and assistance demands are also reported as factors related to peak performance in Para athletes.12–15,17 Longo et al.10 (2016) verified performance age in several Olympic sports and reported 27.8 yrs for canoeing. However, currently, there is a lack of information on the performance trajectories related to age, class, sex, and origin of impairment over time for kayak Para canoe. Precise references regarding these outcomes could guide coaches in monitoring and planning athlete development, as well as in defining realistic performance goals, or even in the adequate choice of a Para sport.12,13 In addition, it is possible to aid public policies to allocate resources by identifying important environmental and sporting factors at different stages of athletes' careers.14

As such, the current study aimed to verify the performance trajectory related to age, classification, and sex of elite kayak Para canoe athletes. The initial hypotheses were as follows: (1) Kayak Para canoe race times have reduced over the years in all classes for men and women; (2) the differences in race times have reduced between classes over the years; (3) male and female elite kayak Para canoe athletes reach peak performance at a similar age in the three classes; (4) elite kayak Para canoe athletes reach peak performance at older ages than those reported for Olympic athletes; and (5) the prevalence of different types of impairments varies across different classes in kayak Para canoe.

METHOD Study Design

A retrospective cohort study that analyzed the times of the kayak Para canoe finals at World Cups, World Championships, and the Paralympics Games in male and female elite athletes between 2015 and 2022. To address the study's aim, the following three main categories were created to be analyzed: athletes' characteristics (sex, class, impairment, and birth date) and included competitions, race time comparisons, and age at peak performance.

Ethics Statement

All data were obtained from sources publicly available online. The human research ethics committee approved the study (protocol n. 5.874.189) and stated that written informed consent was not required. This study conforms to all strengthening the reporting of observational studies in epidemiology guidelines and reports the required information accordingly (see Supplementary Checklist, Supplemental Digital Content 1, https://links.lww.com/PHM/C98).

Data Collection

Data on race results and the athletes were retrieved from databases publicly available online on the Websites of the IPC (https://www.paralympic.org), the International Canoe Federation (https://www.canoeicf.com), and the Websites of the respective countries' Canoe Federations, between 2015 and 2022. These databases contain information about the athletes (name, sex, class, origin of the impairment, and birth date) and competitions (place, date, and weather characteristics—wind speed, air, and water temperature).

Only event finals that were from a valid World Championship (participation of at least six National Federations from at least three continents starting in the event)1 were included in the analyses. In the event that incomplete records were encountered within the databases, specifically of missing birth dates or information regarding the origin of impairment, the athlete was included in the analysis, and missing data were reported (Fig. 1).

FIGURE 1:

Study flowchart based on the following three main outcomes of the study: (1) athletes' characteristics and included competitions; (2) race time comparisons; and (3) age at peak performance. Included data are represented by blue continuous squares, while excluded data are represented by orange dashed squares. NF, national federation.

Procedures

The athletes were analyzed in their respective classes (KL1, KL2, and KL3). The origin of the impairment was stratified into acquired impairment (AI, i.e., postbirth impairment) and congenital impairment (CI, i.e., birth impairment),14,16 because this factor may alter the athletes’ development.18 The age of each athlete, in years, was calculated as a decimal age, subtracting the date of birth from the official date of each championship19:

Ageyears=Competition date−Birth date365.25

Outcomes

The performance (race times, in seconds) and age at peak performance were the main outcomes used to analyze performance in each class for the male (KL1-M, KL2-M, and KL3-M) and female (KL1-F, KL2-F, and KL3-F) kayak Para canoe athletes. Age was treated as an independent variable to be correlated with performance using climatic characteristics (wind speed, air, and water temperature) as covariates. The diagnoses and injuries were used to verify the prevalence in each class for men and women over the years.

Statistical Analysis

The Shapiro-Wilk normality test was used to assess the distribution of the variables. The Jamovi Project Software (version 2.3; 2022) was used. Statistical significance was set at 5% (P ≤ 0.05; two-tailed).

Athletes' Characteristics and Included Competitions

Age over the years for male and female kayak Para canoe athletes and classes are presented as mean and SD as the outcomes were defined as parametric. The origin of the impairment and the type of impairment are expressed in frequencies. One-way analysis of variance with one between-group factor group (in years) with the Bonferroni post hoc test (P ≤ 0.05) was performed for comparisons.

Race Time Comparisons

One-way analysis of variance with one between-group factor group (KL1, KL2, and KL3 and between years) with the Bonferroni post hoc test (P ≤ 0.05) was performed for comparisons of the race times. Cohen d effect size was calculated and classified in the following manner20: trivial (d lower than 0.10); small (d between 0.10–0.29); moderate (d between 0.30–0.49); large (d between 0.50–0.69); very large (d between 0.70–0.89); and perfect (d of 0.90 or greater). Pearson correlation was used to verify the association of the year with race times and relative differences of kayak Para canoe classes and was classified based on the standards: less than 0.40—the level of clinical significance is poor; 0.40 to 0.59—fair; 0.60 to 0.74—good; and 0.75 to 1.00—excellent.21 Ninety-five percent of confidence intervals were used between comparisons. To avoid discrepant race times (e.g., learning effect of adaptations, boats, and the modality; vacancies for countries with athletes without technical index; athletes who withdrew from the race, but have the race time registered as they finish the course), the race times of each final race above the 50th percentile were discarded to prevent extreme and discrepant values from influencing the comparisons.

Age at Peak Performance

Linear mixed effects modeling was used to verify correlations of performance (dependent outcome) with the age-related trajectory for each class (KL1, KL2, and KL2) and sex (male and female). The percentage of the personal best times of finalist athletes with at least five participations in championships was used to establish the age at the peak performance. The analysis was performed considering the percentage of the personal best times as the dependent variable. The expression of the response variable based on the percentage of personal best times enabled comparisons of the effect of age on performance in different sexes and sports classes. Athletes who changed classes were excluded from the analysis. A factor variable that described the case (athlete) was included as a random effect with case-specific slopes and intercepts. Climatic characteristics (wind speed, air, and water temperature) were included as fixed effects to determine whether these factors interact with the relationship between age and performance. One-way analysis of variance with one between-group factor group (KL1, KL2, and KL3, male and female) with the Bonferroni post hoc test (P ≤ 0.05) was performed for comparisons of the age at peak performance.

RESULTS Athletes' Characteristics and Included Competitions

Through the years (2015–2022), a total of 15 competitions (2 Paralympic Games, 7 World Championships, and 6 World Cups) and 85 finals were initially included. KL3 classes and male athletes presented more data (number of athletes or total races time) compared with KL1, KL2, and female athletes for all analyses (Fig. 1). In 2020, all competitions were suspended because of the coronavirus disease 2019 (COVID-19).

There were no significant differences between mean age over the years for male and female Para athletes. The mean age ranged from 32.1 to 35.8 yrs (KL1-M), 28.2 to 32.8 yrs (KL2-M), 27.6 to 32.2 yrs (KL3-M), 30.9 to 36.6 yrs (KL1-F), 32.4 to 36.3 yrs (KL2-F), and 29.3 to 35.3 yrs (KL3-F) over the years. The SD presented a large variation in all classes: 5.4 to 8.5 yrs (KL1-M), 5.5 to 8.8 yrs (KL2-M), 6.2 to 8.6 yrs (KL3-M), 7.4 to 12.2 yrs (KL1-F), 5.6 to 10.0 yrs (KL2-F), and 6.9 to 10.3 yrs (KL3-F) (Fig. 2; Tables 1, 2).

FIGURE 2:

Box plot of the annual progression of mean ages (X) of male and female KL1, KL2, and KL3.

TABLE 1 - Age, the origin of impairment, impairment, and number of male Para canoe athletes from 2015 to 2022 2015 2016 2017 2018 2019 2020 2021 2022 KL1-M n 14 11 9 12 13 — 15 10 Age, yr 35.3 (±7.7) 34.0 (±5.4) 33.6 (±6.7) 34.8 (±5.9) 33.2 (±8.2) — 35.8 (±8.5) 32.1 (±7.9) Origin of impairment  Acquired impairment 100.0% 100.0% 75.7% 100.0% 88.9% — 100.0% 88.9%  Congenital impairment 0.0% 0.0% 14.3% 0.0% 11.1% — 0.0% 11.1% Impairment  Arthrogryposis 0.0% 0.0% 14.3% 0.0% 11.1% — 0.0% 11.1%  Neurological disorder 0.0% 0.0% 0.0% 0.0% 11.1% — 10.0% 11.1%  Spinal cord injury 100.0% 100.0% 85.7% 100.0% 77.8% — 90.0% 77.8% KL2-M n 14 9 10 11 11 — 13 13 Age, yr 32.6 (±8.4) 32.8 (±6.6) 30.2 (±8.8) 28.2 (±6.6) 30.0 (±5.9) — 32.4 (±5.5) 32.4 (±8.5) Origin of impairment  Acquired impairment 88.9% 66.7% 57.1% 77.8% 72.7% — 80.0% 57.1%  Congenital impairment 11.1% 33.3% 42.9% 12.2% 17.3% — 20.0% 42.9% Impairment  Amputation 66.7% 66.7% 57.1% 66.7% 63.6% — 70.0% 57.1%  Dysmelia 0.0% 11.1% 14.3% 11.1% 18.2% — 10.0% 14.3%  Myelomeningocele 11.1% 22.2% 28.6% 11.1% 9.1% — 10.0% 28.6%  Spinal cord injury 22.2% 0.0% 0.0% 11.1% 9.1% — 10.0% 0.0% KL3-M n 14 11 14 13 10 — 14 13 Age, yr 29.1 (±7.5) 29.6 (±6.5) 27.6 (±7.7) 30.8 (±7.2) 30.2 (±6.2) — 32.2 (±8.1) 30.7 (±8.6) Origin of impairment  Acquired impairment 77.8% 77.8% 75.0% 88.9% 75.0% — 80.0% 87.5%  Congenital impairment 12.2% 12.2% 25.0% 11.1% 25.0% — 20.0% 12.5% Impairment  Amputation 66.7% 66.7% 62.5% 66.7% 50.0% — 60.0% 62.5%  Dysmelia 22.2% 11.1% 25.0% 11.1% 25.0% — 20.0% 12.5%  Spinal cord injury 11.1% 22.2% 12.5% 22.2% 25.0% — 20.0% 25.0%

Age is presented as mean (standard deviation) and the origin of disability and disability are expressed in frequency.

No significant difference in age over the years. Missing data are reported in Figure 1.

Acquired impairments were more prevalent than CIs in all classes and years. For male and female KL1 and KL3 classes, spinal cord injury and amputation were the most common impairments, respectively. Amputation was also the most prevalent impairment in KL2-M and spinal cord injury in KL2-F (Table 1 and Table 2).

TABLE 2 - Age, the origin of impairment, impairment, and number of female Para canoe athletes from 2015 to 2022 2015 2016 2017 2018 2019 2020 2021 2022 KL1-F n 9 11 9 9 11 — 13 9 Age, yr 33.8 (±12.2) 32.9 (±11.7) 30.9 (±8.2) 32.4 (±7.4) 32.3 (±8.2) — 34.8 (±8.2) 36.6 (±9.3) Origin of impairment  Acquired impairment 100.0% 100.0% 100.0% 100.0% 100.0% — 100.0% 100.0%  Congenital impairment 0.0% 0.0% 0.0% 0.0% 0.0% — 0.0% 0.0% Impairment  Myelitis 16.7% 12.5% 16.7% 14.3% 14.3% — 0.0% 16.7%  Poliomyelitis 0.0% 0.0% 0.0% 0.0% 0.0% — 16.7% 16.7%  Spinal cord injury 83.3% 87.5% 83.3% 85.7% 85.7% — 83.3% 66.7% KL2-F n 9 11 10 11 11 — 14 11 Age, yr 32.4 (±5.6) 34.6 (±6.7) 36.3 (±10.0) 32.4 (±6.0) 35.1 (±6.3) — 35.1 (±7.1) 33.0 (±6.9) Origin of impairment  Acquired impairment 71.4% 77.8% 66.7% 72.7% 72.7% — 72.7% 75.0%  Congenital impairment 28.6% 12.2% 33.3% 17.3% 17.3% — 17.3% 25.0% Impairment  Amputation 28.6% 33.3% 22.2% 27.3% 36.4% — 27.3% 25.0%  Arthrogryposis 14.3% 11.1% 22.2% 18.2% 18.2% — 18.2% 25.0%  Dysmelia 14.3% 11.1% 11.1% 9.1% 9.1% — 9.1% 0.0%  Neurological disorder 14.3% 11.1% 11.1% 0.0% 0.0% — 0.0% 12.5%  Spinal cord injury 28.6% 33.3% 33.3% 45.5% 36.4% — 45.5% 37.5% KL3-F n 16 10 12 16 12 — 12 12 Age, yr 35.