Triple Jump Performance Parameters and Inter-Limb Asymmetry in the Kinematic Parameters of the Approach Run in International and Paralympic-Level Class T46/T47 Male Athletes

Abstract

Background/Objectives: The triple jump is included in the Paralympic Athletics competition. The aim of the research was to examine the relationship of the phase ratios and the inter-limb asymmetry in the spatiotemporal parameters of the approach run in Paralympic and international-level Class T46/T47 triple jumpers. Methods: Eleven Class T46/T47 male athletes were recorded during the examined competitions. Step length (SL), frequency (SF), and average velocity (ASV) for the late approach run as well as the length and the percentage distribution of each jumping phase (hop, step, jump) were measured using a panning video analysis method. The inter-limb asymmetry was estimated using the symmetry angle. Results: No significant inter-limb asymmetry was found (p > 0.05). In addition, SL, SF, and ASV were not different (p > 0.05) between the steps initiated from the ipsilateral and the contralateral leg regarding the impaired arm. However, the direction of asymmetry for SF was towards the ipsilateral leg to the impaired arm in the majority of the examined athletes. The maximum speed of the approach was correlated with the triple jump distance and the magnitude of asymmetry for AVS was correlated with the vertical take-off velocity and angle for the step. Conclusions: Since the distance of the triple jump related with the peak approach speed added the negative correlation of peak approach speed with the magnitude of the symmetry angle for SL, it is suggested to minimize the asymmetries in the step characteristics during the approach run to improve triple jump performance in Class T46/T47 jumpers.

1. Introduction

“Horizontal” jumps in track and field are considered the athletic disciplines of the long jump and the triple jump. The latter comprises the sequence of a hop, a step, and a jump. Essential biomechanical parameters that define triple jump performance are the speed acquired during the approach run, the conversion of horizontal-to-vertical velocity at the contact phases of the hop, the step and the jump, and the ratio between the duration of the contact and aerial time in each separate phase of the triple jump [1,2]. The contribution of the arm swing technique is also of importance since the take-off parameters are optimized due to the energy flow generated by the work produced at the shoulders, which results in the application of greater impulse, the faster transition from braking to propulsion during the supports, and the maintenance of balance, especially at the contact phase of the step [3,4].

It is suggested that there is an inter-relationship between the technical execution of the triple jump and the biomechanical factors that define triple jump performance at an individual level [5]. For example, the kinematics of the last steps of the approach, namely the vertical velocity, seem to affect the jumpers differently based on how they distribute the separate distance of the hop, the step, and the jump within the triple jump [6]. Besides velocity, another important factor that influences the distribution ratio is strength [7]. To optimally combine both velocity and strength, jumpers need to coordinate their movement patterns in a variable manner to respond to the inter-relationships among the biomechanical factors and to generate a robust solution aiming for the best performance [8]. Among the important elements in this procedure is the generation and control of angular momentum [4] to maintain balance in a manner that the applied ground reaction forces will be optimally used to increase performance. Another issue is the generation and the sequencing of the joints’ torque [7] to allow for the optimization of the energy flow to achieve effective take-off conditions (take-off velocity, angle, and height) in the hop, step, jump, and, consequently, triple jump performance. Finally, the efficiency of the transition from braking to propulsion during the support phases is essential for the preservation of the acquired mechanical energy during the approach until the termination of the jump in the sand pit [9].

To optimize the outcome of the above-mentioned performance-defining factors, athletes exhibit a large amount of musculoskeletal loading at their take-off leg [10,11]. As the nature of the discipline requires the take-off to be performed unilaterally (i.e., right-right-left leg as the take-off leg for the hop, the step, and the jump, respectively), the loading is considered to be associated with limb dominance [12], while the strenuous repetitions executed in both training and competition are proposed to increase inter-limb asymmetry in force application and power production parameters [13]. However, research conducted in athletes competing in the athletics jumping events revealed no significant inter-limb asymmetries in various vertical jump and balance tests [14,15].

It is not uncommon for able-bodied jumpers to present a considerable inter-limb asymmetry in the step parameters, namely the step length (SL), frequency (SF), and average velocity (AVS) during the long jump approach [16]. Regarding lower limb amputee long jumpers, larger inter-limb asymmetry was reported for average sprinting vertical support forces in comparison to non-amputee long jumpers [17]. In more detail, SF asymmetry was negatively correlated with long jump performance, while the direction of SF asymmetry was towards the lower limb with the prosthesis [18]. Although wearing a prosthesis is required of Paralympic long jumpers, there is no solid evidence of whether this has a beneficial effect on the inter-limb asymmetry for the step parameters of the sprinting action during the approach run [19,20].

Most of the research evidence about Paralympic athletic jumpers is derived from studies examining lower limb amputees [17,18,21,22,23,24,25,26,27], while limited research has been conducted on Para-Athletes with upper limb amputation [28] or upper limb impairments, i.e., Class T45, Class T46, and Class T47 jumpers [29]. As defined by the International Paralympic Committee, those eligible for competition in track and field in the above-mentioned classes are athletes with “upper limb/s affected by limb deficiency, impaired muscle power or impaired passive range of movement” [28]. As further defined in World Para Athletics, eligibility for competition in Class T46 jumping events includes the satisfaction of criteria, namely the shoulder flexion/extension loss and elbow flexion loss of 3 muscle grade points, whereas the criteria for Class T47 are the loss of 3 muscle grade points in elbow extension and wrist flexion/extension [30]. The option to wear an upper limb prosthesis or not during competition is a matter of choice for Class T47 athletes.

There is limited information regarding the outcome of the choice of Para-Athletes to wear an upper limb prosthesis in track and field, and in the jumping events in particular. In able-body persons, the angular momentum generated during running due to the forward and backward arm swing is canceled [31] and results in the desirable balanced contribution of the body segments’ swing and thus to less asymmetry in running. Besides the favorable contribution to lateral balance, the arm swing minimizes the energy cost during movement [32]. Upper arm amputee athletes were shown to present inter-limb asymmetries in the vertical ground reaction forces during the contact phase of running, as the leg of the contralateral side of the impaired arm was found to apply higher peak force [33]. It was also found that there is an increased importance of the arm swing when running speed increases [33]. However, wearing an upper limb prosthesis contributes to increased forearm mass, but this addition is considered to alter the inter-limb asymmetry in running kinetics [34]. There is evidence that long jump performance was increased because the horizontal velocity was increased when using an upper arm prosthesis [35]. Furthermore, the use of an upper arm prosthesis led to reduced inter-limb asymmetry regarding SL and AVS when compared to approach runs without the prosthesis because of the increased moment of inertia around the shoulder [36]. Nevertheless, in the case of long jump, it is not clear if the use of an upper limb prostheses results in an improvement in long jump performance, as research has suggested the opposite [37]. These limited research findings highlight the importance of acknowledging the importance of interventions regarding the angular momentum produced by the arm swing in upper-limb amputee jumpers, with the use of prosthesis for example, to reduce asymmetry-related deficits in performance and/or to prevent asymmetry-related injuries.

There has lately been an on-going interest in Paralympic sports, but scarce scientific evidence is available about the inter-limb asymmetry in the step parameters of Class T45-T47 triple jumpers and its association with triple jump performance. The arm swing is a technique element that is important for performance, but the athletes in the above-mentioned classes have upper limb deficiencies and/or amputations and impairments and thus have a disadvantage to optimizing their performance in the triple jump. The purpose of the study was to examine these variables and their relationships in a cohort of top international-level Para-Athletes. It was hypothesized that significant asymmetries will be observed in the SL, SF, and AVS of the approach run steps and that the magnitude of asymmetry in these step parameters will be related to decreased performance in the triple jump and its kinematic parameters.

2. Materials and Methods

2.1. Participants

Eleven Class T46/47 male triple jumpers were examined in the 2012 London Paralympics and two international Para-Athletics meetings held in Greece. Following the official classification by the IPC medical boards, these top-level Para-Athletes served as the convenience sample to conduct the study. The study was performed following the recommendations of the Declaration of Helsinki and after the acquirement of ethical approval from the Institutional Ethics Committee (IRB00003099).

2.2. Data Acquisition

To establish consistency and thus the reliability of the measures, a group of experienced supervisors ensured the conduction of the three data acquisition sessions by implementing the same experimental methodology and set-up. This included the calibration of the approach lane with custom 5 × 5 cm reference markers to form 1.00 × 1.30 m reference zones along the entire run-up and of the positioning of the fixed, stable tripod camera on the stands (14.3 m from the near side-line of the runway; approximately 3 m above the track; 2 m after the take-off board [18]). The last 12 steps of the run-up, the hop, the step, the jump, and the landing of all triple jump attempts were recorded with a panned high-speed digital camera (Exilim-Pro-EX-F1, Casio Computer Co., Ltd., Shibuya, Japan; sampling rate: 300 fps; resolution: 512 × 384 pixels).

The peak approach run speed (V_MAX) was measured with a Stalker ATS 5.02 radar (Applied Concepts Inc., Richardson, TX, USA; sampling rate: 46.9 Hz), which was positioned on a fixed tripod (height: 1 m) placed 10 m from the far end of the sand pit. The axis of the speed radar pointed at the center of the jumpers’ lower torso [18]. The experimental set-up is depicted in Figure 1.

2.3. Data Analysis

The analysis was conducted only for the best attempt (criterion: the largest official triple jump distance) recorded for each participant. The extraction of the step kinematics was conducted, following the procedures described in detail elsewhere [18,38]. As the triple jump technique is characterized by step length adjustments between the larger penultimate and the shorter last step (1LS_ADJ) [39], the inter-limb asymmetry for SL, SF, and AVS was examined for five steps initiated from the impaired side (SIS) and five steps initiated from the intact side (ILS) in the late approach (12th-to-last to 3rd-to-last steps) using the symmetry angle (Θ_SYM) [40] as follows (Equation (1)):

$${\mathsf{\Theta }}_{\mathrm{SYM}}={\displaystyle \frac{\left(45^{\circ }-\mathit{arctan}\left(\frac{x_{\mathrm{ILS}}}{x_{\mathrm{SIS}}}\right)\right)}{90^{\circ }}}\times 100\%$$

(1)

where Θ_SYM is the symmetry angle, x_SIS is the mean value for the SIS steps, and x_ILS is the mean value for the ILS steps. However, if (Equation (1)) was as follows:

$$\left(45^{\circ }-\mathit{arctan}\left({\displaystyle \frac{x_{\mathrm{ILS}}}{x_{\mathrm{SIS}}}}\right)\right)>90^o$$

(2)

then Equation (2) would be modified to (Equation (3)):

$${\mathsf{\Theta }}_{\mathrm{SYM}}={\displaystyle \frac{\left(45^{\circ }-\mathit{arctan}\left(\frac{x_{\mathrm{ILS}}}{x_{\mathrm{SIS}}}\right)-180^{\circ }\right)}{90^{\circ }}}\times 100\%$$

(3)

A positive Θ_SYM indicated the direction of asymmetry towards larger ILS values, whereas a negative Θ_SYM indicated a larger SIS value. However, absolute Θ_SYM values were used to examine the magnitude of asymmetry using procedures presented in detail in the past [16,41].

The phase ratios and the kinematics of the take-off in each separate phase of the triple jump (hop, step, jump) were calculated according to Panoutsakopoulos et al. [42]. Based on the percentage distribution of each phase, the performed triple jump techniques were identified as follows [39]:

• hop-dominated technique in the cases where the hop was ≥2% larger than the jump;
• jump-dominated technique in the cases where the jump was ≥2% larger than the hop;
• balanced technique in the cases where the difference between the hop and the jump was <2%.

Regarding the arm swing technique, their identification was conducted as follows [42]:

• double-arm swing techniques were the cases where, at the instant of take-off, the wrist of the contralateral arm to the support leg was in front of the body while the ipsilateral arm was simultaneous and harmonic at a parallel position across all take-offs;
• single-arm swing techniques were the cases where, at the instant of take-off, the wrist of the contralateral arm to the support leg was in front of the body while the ipsilateral arm was conducting simultaneously a harmonical opposing arm movement across all take-offs;
• mixed-arm swing techniques where the cases where a combination of single- and double-arm swing techniques were observed within a single triple jump attempt.

2.4. Statistical Analysis

The Shapiro–Wilk test (p < 0.05) was conducted to check the normality of the distribution of the examined parameters. Its results indicated that the values of the official result, the distance loss at the take-off board, the x_SIS for SL, and ASV as well as Θ_SYM for SL and SF were not normally distributed. Based on the normality check, the possible differences between the x_SIS and x_ILS values for SL and AVS were examined with the Wilcoxon signed rank test, whereas the possible differences between the x_SIS and x_ILS values for SF were checked using the paired samples T-test. The relationship of Θ_SYM for AVS with the triple jump phase parameters was checked with Pearson’s correlation (|r|: 0.00–0.10 = negligible correlation; |r|: 0.10–0.39 = weak correlation; |r|: 0.40–0.69 = moderate correlation; |r|: 0.70–0.89 = strong correlation; |r|: 0.90–1.00 = very strong correlation). The relationship of Θ_SYM for SL and SF with the triple jump performance and phase parameters was evaluated using the Kendall’s τ_b (|τ_b|: 0.00–0.05 = negligible correlation; |τ_b|: 0.06–0.25 = weak correlation; |τ_b|: 0.26–0.49 = moderate correlation; |τ_b|: 0.49–0.70 = strong correlation; |τ_b|: 0.71–1.00 = very strong correlation) [43]. The statistical analyses were performed with the IBM SPSS Statistics v.29.0 software (International Business Machines Corp., Armonk, NY, USA), where the level of significance was set at a = 0.05.

3. Results

The average ± standard deviation (SD) of the official result was 13.67 ± 1.09 m. Eight of the examined triple jumpers used the ILS as the take-off leg for the hop.

Regarding the arm swing techniques, five participants executed the triple jump with a single-arm technique, while five performed their attempts using a mixed-arm technique. Due to a shoulder-level amputation, this classification could not be conducted for one jumper.

3.1. Approach Run

No significant (p > 0.05) x_SIS to x_ILS differences were revealed for SL (Z = 0.445, p = 0.656), SF (t = 0.551, p = 0.620), or AVS (Z = 1.245, p = 0.213). More than half of the athletes (6/11) failed to perform the “larger penultimate–shorter last step” technique. The results of the examined parameters are depicted in

Table 1. Results for the examined parameters of the approach run (n = 11).

Parameter	Minimum	Maximum	Mean	SD	Skewness	Kurtosis
Distance loss at take-off (m)	0.01	0.19	0.10	0.07	0.19	−1.90
VMAX (m/s)	7.80	9.57	8.78	0.58	−0.14	−0.95
1LSADJ (%)	−12.92	11.65	−1.05	8.55	−0.14	−1.41
SL − xSIS (m)	1.33	2.33	1.99	0.35	−1.21	0.17
SL − xILS (m)	1.28	2.32	1.99	0.31	−1.30	1.62
SL − ΘSYM (%)	0.11	6.90	1.61	2.05	1.97	4.19
SF − xSIS (Hz)	2.44	5.06	3.84	0.71	−0.34	0.59
SF − xILS (Hz)	2.58	4.54	3.90	0.55	−1.51	2.59
SF − ΘSYM (%)	0.03	7.00	2.27	1.80	1.88	5.16
AVS − xSIS (m/s)	5.41	9.42	8.03	1.37	−1.08	−0.14
AVS − xILS (m/s)	5.50	9.97	8.27	1.41	−0.72	−0.19
AVS − ΘSYM (%)	0.24	3.69	1.79	1.34	0.21	−1.76

Note: V_MAX: maximum speed during the approach; 1LS_ADJ: the difference between the penultimate and last step length; SL: step length; x_SIS: average value for the step initiated with the ipsilateral leg to the impaired arm; x_ILS: average value for the step initiated with the contralateral leg to the impaired arm; Θ_SYM: symmetry angle; SF: step frequency; AVS: average step velocity.

.

At the last seven steps, a fluctuation between the SIS and ILS steps was revealed in the progression of SL, SF, and AVS (Figure 2). On the other hand, the step time was stable after the seventh-to-last step.

The Θ_SYM magnitude was 1.6 ± 2.0%, 2.3 ± 1.8%, and 1.8 ± 1.3%, for SL, SF, and AVS, respectively. No significant (p > 0.05) asymmetry was revealed for any of the examined step parameters. Regarding the direction of asymmetry, SIS had a larger frequency of observations for SF and slightly more cases for SL, while the direction of asymmetry was slightly towards ILS for AVS (Figure 3).

3.2. Hop-Step-Jump Take-Off Kinematics

The kinematic parameters for the triple jump are presented in

Table 2. Results for the kinematic parameters of the separate phases of the triple jump (n = 11).

Parameter	Hop	Step	Jump
distance (m)	5.19 ± 0.36	3.75 ± 0.73	4.83 ± 0.44
phase ratio (%)	37.77 ± 1.64	27.04 ± 4.33	35.19 ± 3.45
horizontal velocity (m/s)	8.32 ± 0.49	7.72 ± 0.50	6.26 ± 0.25
vertical velocity (m/s)	2.44 ± 0.13	1.58 ± 0.35	3.01 ± 0.25
take-off angle (deg)	16.63 ± 0.80	11.07 ± 3.35	25.85 ± 2.23

. Based on the phase ratios, four jumpers were identified as hop-dominated and one as jump-dominated, while six performed the triple jump with a balanced technique. At the instant of take-off for the jump, the horizontal velocity was decreased by 28.4 ± 5.0% compared to V_MAX.

The official triple jump distance was strongly positively correlated with V_MAX (τ_b = 0.51, p = 0.029), the distance of the hop (τ_b = 0.67, p = 0.004), and the vertical take-off velocity for the hop (τ_b = 0.70, p = 0.003). The Θ_SYM magnitude for AVS was moderately positively correlated with the vertical take-off velocity and angle for the step (r = 0.61, p = 0.045 and r = 0.60, p = 0.049, respectively). Finally, the Θ_SYM magnitude for SL was moderately negatively correlated with V_MAX (τ_b = −0.48, p = 0.042) and strongly positively correlated with the distance of the hop (τ_b = −0.64, p = 0.006).

4. Discussion

The results of the present study revealed that no significant inter-limb asymmetries existed for the step parameters of the approach run in international and Paralympic-level Class T46 and Class T47 male triple jumpers. Thus, the first hypothesis of the study was not confirmed. As for the second aim of the study, namely the examination of the relationship of the magnitude of asymmetry with the triple jump performance parameters, the outcome of the analysis was that the larger asymmetry in step length was related to a longer hop distance, while larger asymmetry in average step velocity was related to larger vertical take-off velocity and angle for the step. These results partially confirmed the second hypothesis of the study stating that the magnitude of asymmetry would be related with the kinematical parameters that suggest decreased performance in the triple jump.

The level of performance of the examined cohort of top Class T46 and Class T47 male triple jumpers was inferior to able-bodied top male athletes [38,42,44,45,46] and to national-level male junior triple jumpers [47]. However, as referred to in previous preliminary reports on Class T47 male athletes [48], the average triple jump performance was higher. The magnitude of the peak velocity acquired during the approach run is in agreement with the above-mentioned studies. The peak approach velocity was moderately negatively correlated with the magnitude of asymmetry for the step length. Previous observations show that the step length of the steps initiated from the contralateral leg to the impaired upper arm is larger than the steps initiated from the ipsilateral leg [36]. The researchers also reported that the difference in step length was higher compared to the differences in step frequency and average step velocity [36]. These findings were attributed to the imbalanced contribution of the arm swing between the intact and impaired upper limb on the angular momentum of the whole body about the transverse axis, which is enlarged as jumpers approach the take-off board [36]. It is suggested that there should be a cancelation of the angular momentum generated due to the forward and backward arm swing to maintain balance during running [31], thus the examined jumpers were faced with a mechanical disadvantage.

The finding that the direction of asymmetry for step frequency was towards the ipsilateral leg to the impaired arm in the majority of the examined athletes could also be explained as the effort to balance the inter-limb difference resulting from the unequal contribution of the arm swing. It was found that the peak vertical ground reaction forces are applied to the contralateral side of the impaired arm in upper-arm amputee athletes [33]. This was suggested to be caused by the differences in the vertical momentum due to the upper limb impairment. Thus, the greater force in the vertical direction could affect the vertical take-off velocity and take-off angle, which resulted in differences in step frequency. This could also explain the finding that the step frequency was stabilized in the last two steps of the approach. The common pattern of the step frequency progression during the approach in able-bodied triple jumpers is that step frequency remains unchanged during the late approach (up to six steps prior the take-off for the hop) [38] and increases at the very last step [39]. This was not evident in the examined athletes.

As mentioned above, the last two steps of the approach were conducted with similar step frequency. In addition, more than half of the examined triple jumpers did not perform the last two steps with the “larger penultimate–shorter last step” technique. Observations in able-bodied triple jumpers suggest that this technique is not as common as in the long jump [39], since its adoption leads to a higher vertical take-off velocity and take-off angle for the hop, which is not desirable for the optimization of the entire triple jump distance. Furthermore, no significant inter-limb asymmetries were observed for the examined approach step parameters. This finding can be attributed to the fact that most of the examined Class T46/T47 athletes performed the triple jump with a shorter approach compared to elite able-bodied jumpers (17–26 steps) [39]. There is a possibility that they did not reach their potential peak approach velocity and thus they could control the magnitude of asymmetry, as inter-limb asymmetry was found to increase as speed increases in upper arm amputee athletes [33]. By controlling the asymmetry in the approach step parameters, the participants could focus to optimally execute other important aspects of the approach run, such as the step regulation, to achieve accuracy in the foot placement at the take-off board [49].

The majority of the examined triple jumpers executed two of the take-offs, i.e., the hop and the step, using the contralateral leg to the impaired limb as the take-off leg. As described above, this option leads to a longer step length in sprinting. This could mean that this selection of take-off leg is due to the advanced power generation capabilities of the leg contralateral to the impaired limb [36]. It is of interest to note that higher swing velocity for the deficient arm in upper limb amputees in running has been reported in the past [50]. As it is crucial for the optimization of the triple jump performance to perform the support phases of the hop, step, and jump with a high horizontal-to-vertical velocity conversion in the shortest possible contact time [38,42,51], the higher swing velocity for the impaired arm could contribute to the satisfaction of this constrained demand.

The participants performed their attempts, evenly exhibiting the single- and mixed-arm swing techniques. The vast majority of male able-bodied triple jumpers use the mixed-arm swing technique [38], as it is proposed to optimize the triple jump distance [52]. In most cases, the mixed-arm swing technique is observed as the transition from the single- to the double-arm swing technique. This is because horizontal velocity, during the support phases, is reported to decline as the triple jump progresses [45,53,54,55]. This leads to the need for greater power production [3] and balance [4] to optimize the take-off parameters. Given the upper arm impairment, it seems logical for the examined triple jumpers to employ the mixed-arm swing technique.

Compared to elite able-bodied triple jumpers [38,45,46], most of the participants also performed the triple jump with the balanced technique. A considerable number of the examined athletes (4/11) executed the triple jump with a hop-dominated technique. The past literature has suggested that a relatively small hop percentage in a hop-dominated technique may result in a larger actual triple jump distance [44,56]. In the present study, the distance of the hop was positively correlated with the magnitude of asymmetry for the step length, which, as discussed earlier, is related to the laterality of the upper limb impairment. In addition, as the upper limb impairment might be related to the power-production capabilities of the contralateral leg, the notion that differences in the regulation of the lower limb stiffness result in the adoption of different phase distribution techniques [57] should be kept under consideration. Nevertheless, the percentage distribution of the step in the present study (27.0 ± 4.3%) is smaller than that reported for top triple jump athletes (about 30%) [38,42,44,45,46]. This is of importance, as the length of the step is crucial for the total jumping distance [58,59]. In the present study, the kinematical parameters of the take-off for the step, namely the vertical take-off velocity and the take-off angle, were positively correlated with the magnitude of asymmetry for the average step velocity. Based on the above, the way in which the approach run is performed is an essential factor for success in Class T46/T47 triple jumpers.

The results revealed that the magnitude of asymmetry for step length was negatively related to V_MAX. As the peak approach velocity is the most defining parameter for triple jump performance [38,42], large step length asymmetry comprises a disadvantage for performance. The imbalance in angular momentum caused by the upper-limb impairment can either be compensated with an increased shoulder range of motion or with lower limb extension angular velocities [36]. Also, the magnitude of asymmetry for step length was related to the distance of the hop, which in turn was related to the triple jump performance. Although this seems beneficial for the Class T46/T47 triple jumpers, this larger hop distance could lead to an increased risk of injury [60]. On the other hand, the magnitude of asymmetry for average step velocity was related to the vertical take-off velocity and the take-off angle for the step. The aim of a triple jumper is to exhibit a lower take-off angle in the step rather in the hop or the jump [39]. Thus, a fast horizontal-to-vertical velocity conversion is required [1,59,61]. To do so, power is required [3], and the most appropriate manner is the utilization of the double-arm technique. However, due to their impairment, this was not feasible for the participants.

To generalize the findings of this research, attention must be paid to the limitations of this study. We recognize that the small size of this convenience sample deprives the opportunity to compare the subgroups of the examined Para-Athletes (Class T46 and Class T47) and to gain further insight in the biomechanics of the triple jump technique in athletes with upper limb impairment. Nevertheless, due to the scarcity of elite athletes, this is often the case in this area of research. Another topic is that the study was conducted using only the best attempt. This does not allow for an analysis of the step regulation patterns that could possibly provide further information about the approach step parameters [62]. Future research should consider the above factors. Furthermore, the video recording method did not allow for an examination of the possible trunk rotation and its effect on the results. Nevertheless, the use of an upper-arm prosthesis revealed beneficial advantages in both the approach [36] and the take-off [35,37] in long jumpers with upper arm impairments. Thus, it would be of interest to examine if the same positive effects occur in Class T46 and Class T47 triple jumpers in future research, as there is a gap in the literature about upper limb prosthesis and athletics jumping events [63].

5. Conclusions

The results revealed no significant inter-limb asymmetry for the approach step parameters in Class T46/47 triple jumpers. The magnitude of asymmetry for the step frequency and average step velocity was correlated with the triple jump kinematic parameters that are essential for the optimization of performance. The inter-limb asymmetry of the step parameters should be monitored by coaches and practitioners, as the magnitude of inter-limb asymmetry in step length is negatively related to V_MAX, which in turn is positively related to performance. In addition, the magnitude of inter-limb asymmetry in step length is positively related to the distance of the hop, which is important for the total length of the triple jump but could also cause excessive loading. Thus, coaches and practitioners could consider the use of upper limb prosthesis to reduce the inter-limb asymmetry in step length and consequently to increase approach velocity as a result of the improvement in the lateral balance. In addition, the decrement of the inter-limb asymmetry in the approach step parameters could enhance the horizontal-to-vertical velocity conversion and to reduce the negative related effect of increased take-off parameters for the hop and the step. In conclusion, effective training programs in Class T46/47 triple jumpers should aim to improve the approach speed by minimizing asymmetry, and by implementing the optimum arm swing technique for a faster transition from braking to propulsion in the shortest possible contact time, with the maintenance of balance to achieve greater impulse during the support phases.