Sprinting represents a fundamental form of human locomotion and a critical determinant of athletic performance across multiple sports, including soccer, baseball, and rugby (Skoglund et al., 2023). The ability to accelerate rapidly and sustain high sprinting velocity is essential not only crucial for sprinters, but also a key component of successful performance in team sports that require repeated sprints (Bella et al., 2023). For example, short-distance sprints have been identified as the most frequent actions in scoring situations, executed by both goal scorers and supporting players (Faude et al., 2012). Additionally, team athletes with different competition standards exhibit varying sprinting abilities (Skoglund et al., 2023). Research also indicates that elite players become faster over time (Hisdal et al., 2013), suggesting that sprint performance enhancements require more attention and exploration.

As the main interface between the feet and the ground, running shoes was claimed to affect the biomechanical characteristics of the knee and ankle joints during running (TenBroek et al., 2014), which may further affect the risk of chronic sports injury (Sinclair, 2014). Due to technological advancements in structural and material engineering, running shoes with various functional characteristics are constantly being introduced, such as cushioning, stability, and minimalist running shoes (Davis, 2014; Sun et al., 2020).

There have been many studies on the biomechanical characteristics’ changes caused by the structure of running shoes. For instance, wearing shoes with heel cup protection for 4 weeks can decrease plantar pressure, plantar fascia stress, calcaneal stress, and self-perceived pain ratings (Li et al., 2018). Shoes with a greater heel-to-toe drop induce stronger knee flexion torque during the propulsion period and smaller knee extension torque during the cushion period (Besson et al., 2017), although different drops do not result in different injury risks (Malisoux et al., 2016). Soft midsole designs can reduce ground impact force and loading rate, thereby lowering the risk of impact-related injuries (Sterzing et al., 2013). Studies on shoelace design showed that a six-eyelet lacing pattern results in higher peak heel pressure and loading rate compared to a seven-eyelet lacing pattern, without differences in perceived comfort between the two patterns (Hagen et al., 2010).

In addition to the aforementioned, nowadays running shoe designs incorporate carbon fiber materials to increase running performance. Previous research revealed that carbon plates inserted at midsole could increase the bending stiffness, which could reduce metatarsophalangeal joint energy loss, thereby improving running performance and economy (Stefanyshyn and Nigg, 2000; Madden et al., 2016). Regarding the design of carbon plates, studies have compared and analysed the biomechanical effects of different carbon plate thicknesses and placement positions, which found that using thicker carbon plates (2 or 3 mm) close to the outsole can better alleviate plantar pressure (Song et al., 2023). More studies have reported on the advantages of carbon plates running shoes compared to regular running shoes, such as the Vaporfly 4% running shoes with inserted carbon plates, which could save 3.83%, 2.82%, and 2.70% of energy requirements on flat/uphill and downhill roads compared to traditional marathon running shoes with relatively thinner midsole (Whiting et al., 2022). However, there are no relevant reports on the differences in carbon plate shapes and designs, and previous studies have focused on typical jogging speeds (from 3.3 km/h to 3.61 km/h). Further exploration is needed for the biomechanical differences in running shoes designed with different carbon plate geometries, especially at a fast enough sprint speed.

Previous analysis has explored the effects of differential designed running shoes on risk factors related to chronic running pathology, but these biomechanical parameters are usually explored through discrete point analysis. For biomechanical parameters analysed according to time normalization, statistical parameter mapping (SPM) is more effective for analysis, because this method can detect data differences throughout the entire time window, thereby reducing the occurrence rate of Class II errors (Pataky et al., 2013). This study employs the SPM method to analyze the differences in lower limb biomechanical characteristics when wearing full-scale carbon plate geometry (FC) and Y-shaped carbon plate geometry (YC) during sprinting. We hypothesize that YC shoes provide better ankle stability during sprints, while FC shoes induce stronger longitudinal bending at the metatarsophalangeal joint.

As shown in Table 1, no significant differences were observed between YC and FC shoes in total foot contact time, cushion time, propulsion time, peak braking horizontal force, peak propulsion horizontal force, peak plantarflexion moment, or peak knee extension moment (all p > 0.05). However, the peak vertical impact force was significantly lower in the FC shoes compared with the YC shoes (2.90 ± 0.291 BW vs. 3.14 ± 0.447 BW, p = 0.003, d = 0.49).

During sprinting, significant differences in ankle joint kinematics were observed between the two shoe conditions. Compared with YC, FC shoes showed a significantly reduced plantarflexion angle at toe-off (20.7° ± 4.94° vs. 25.1° ± 5.56°, p < 0.001, d = 1.18) and peak plantarflexion angle (20.9° ± 4.92° vs. 25.4° ± 5.32°, p < 0.001, d = 1.08). Moreover, the ankle sagittal range of motion was significantly smaller in the FC condition (39.3° ± 5.65°) compared with the YC condition (43.5° ± 5.46°) (p < 0.001, d = 0.75). No significant differences were found in knee flexion angles at touchdown or toe-off, plantarflexion angle at touchdown, or peak dorsiflexion angle (all p > 0.05). The detailed results are presented in Table 2.

Further SPM analysis indicated a significant difference emerged in the vertical ground reaction force. As illustrated in Figure 3, this difference occurred between 38% and 65% of the stance phase, during which athletes wearing YC experienced significantly greater vertical ground reaction forces compared with those wearing FC (α = 0.05, t * = 3.296).

In terms of the kinematic parameters of the hip joint, Figure 4 shows the angle curve changes in the sagittal, frontal, and horizontal planes of the hip joint during a stance time. The data shows that there is no statistical difference in the kinematic parameters of the hip joint between sprinters wearing YC and FC during the entire stance time.

In terms of knee joint kinematics parameters as shown in Figure 5, only a short period (58%–63%) of a stance time shows different between two conditions. Specifically, wearing FC during sprinting induce a significantly larger knee flexion angle compared to YC (α = 0.05, t * = 2.949). However, there was no significant difference between the two pairs of shoes in terms of knee joint adduction/abduction and internal/external rotation.

The shape of carbon plate induced significantly impact on ankle joint kinematic variables, as shown in Figure 6. Specially, in the initial and the vast majority (30%–100%) period of stance time during sprinting, there is a significantly greater tendency of ankle eversion when wearing FC compared to the YC (α = 0.05, t * = 3.138), and wearing YC induces a more pronation trend in the 0%–15% stance period (α = 0.05, t * = 3.230); (Figure 6); But there was no significant difference between the two pairs of shoes regarding range of motion in plantar/dorsiflexion.

With regard to metatarsophalangeal joint kinematic variables, the metatarsophalangeal joint results in a significantly greater extending trend when wearing YC than FC (α = 0.05, t * = 3.198) during the 10%–80% period of a stance time as shown in Figure 7, but no difference was detected between two shoe conditions regarding inversion/eversion and abduction/adduction curves, except only a short period (less than 10%) of stance time.

In this study, no significant differences were observed between FC and YC shoes in most spatiotemporal and kinetic parameters, such as foot contact time, braking and propulsion horizontal forces, or knee extension moment. This indicates that the two plate geometries did not substantially alter the global timing or force generation patterns of sprinting. However, a notable difference was found in the vertical impact force, where FC induced significantly lower peak vertical impact forces compared with YC. This reduction is likely related to the greater longitudinal stiffness of the full-length carbon plate, which may distribute loads more evenly across the stance phase and thereby attenuate the magnitude of impact at initial contact. Previous research also revealed stiffer shoes induced less impact loading, rather than the maximalist shoes (Kulmala et al., 2018), supporting the present findings.

In terms of joint kinematics, FC resulted in a smaller peak plantarflexion angle and reduced sagittal-plane ankle range of motion compared with YC. These alterations suggest that the full-length plate constrains ankle mobility, which may improve energy transfer efficiency but potentially compromise natural joint motion and increase demands on surrounding stabilizing structures. Conversely, the YC configuration allowed for greater plantarflexion and range of motion, which may facilitate propulsion but could also increase mechanical demands on the plantar fascia and Achilles tendon (Sinclair et al., 2021).

Taken together, these results highlight distinct biomechanical responses associated with different plate geometries: the FC shoe appears to enhance impact attenuation and motion control, whereas the YC shoe favours greater ankle mobility and push-off potential. From a practical perspective, this implies that shoe design should be tailored to athlete profiles and training needs: FC-type shoes may better serve athletes prioritizing energy efficiency and impact reduction, whereas YC-type shoes may be advantageous for athletes seeking enhanced ankle flexibility and propulsion capacity (Esculier et al., 2015).

Furthermore, this study used the SPM method to compare the biomechanical characteristics between a full-scale carbon plate designed running shoes (FC) and a Y-shaped carbon plate designed running shoes (YC). The joint angle changes of the hip, knee, ankle, and metatarsophalangeal joints, as well as the vertical ground reaction force, were analysed and compared. The advantage of SPM is that it allows continuous comparison across the entire stance phase, rather than focusing only on discrete values, thereby providing a more detailed description of temporal differences.

The vertical ground reaction force curves indicated consistent general patterns between the two shoes. Nevertheless, SPM revealed significantly greater vertical GRF in YC than FC between 38% and 65% of the stance phase (p < 0.001). This may be attributed to the higher longitudinal stiffness of the full-scale carbon plate in FC shoes, which shifts the center of pressure forward during the push-off phase, thereby increasing the joint moment arm and decreasing the ground reaction forces (GRFs) (Oh and Park, 2017). Supporting this interpretation, previous studies also reported that vertical impact peaks were lower in stiff shoe conditions compared with softer shoes during treadmill (Malisoux et al., 2023) and the runway (Pollard et al., 2018).

Wearing the two types of running shoes has no statistical effect on hip and knee joint kinematics during stance, except for a small transient difference in knee extension. These results are consistent with prior studies, which generally suggest that carbon plates primarily affect metatarsophalangeal and ankle function, with limited influence on hip and knee mechanics (Willwacher et al., 2014; Madden et al., 2016; Oh and Park, 2017).

The ankle sagittal-plane angle curves showed no differences in the plantarflexion–dorsiflexion transition. However, in the frontal plane, FC induced significantly greater eversion amplitude than YC throughout 30%–100% of stance. In this study, ankle stability was operationally defined using the eversion angle during stance, with larger eversion amplitudes interpreted as indicative of reduced mechanical stability at the subtalar joint. Greater eversion excursion may impair ankle stability, potentially increasing the risk of inversion-related injuries (Hannigan and Pollard, 2020). This result also supports the original hypothesis that wearing YC shoes can ensure better ankle stability during sprints. The poor stability of FC shoes may be related to stiffer midsole by the full-scale carbon plate, even if a previous paper claimed the maximal ankle eversion angle was consistent between different stiffness shoes conditions (Malisoux et al., 2023). One plausible explanation is that the sprinting speed (25.2 km/h) adopted here is much faster than the speed in Malisoux’s research (10 km/h), and the higher intensity sprints might amplify the instability differences caused by the stiffness of the shoes.

The results of this study revealed greater metatarsophalangeal joint flexion and extension amplitude while wearing YC than FC shoes. Specifically, YC shoes induced a stronger extension tendency at the metatarsophalangeal joint during 10%–80% of stance, while FC shoes maintained a more flexed configuration throughout stance. Reduced metatarsophalangeal mobility at the metatarsophalangeal joint was related with a stronger forefoot bending stiffness (Madden et al., 2016), so the design of a full-scale carbon plate induced stronger forefoot bending stiffness compared to the Y-shaped carbon plate. Furthermore, previous research found that increasing the bending stiffness of the metatarsophalangeal joint could reduce energy loss at the joint, thereby achieving a positive impact on running performance (Stefanyshyn and Nigg, 2000). Accordingly, the FC shoe may promote energy efficiency by limiting forefoot motion, but this comes at the cost of restricted joint mobility and potentially increased local loading.

Overall, this study revealed that different shapes of carbon plates embedded in shoes resulted in different biomechanical characteristics during sprinting. Specifically, FC shoes with a full-scale carbon plate design exhibited higher longitudinal bending stiffness than YC shoes with a Y-shaped carbon plate, potentially reducing energy loss during sprinting. However, FC shoes induced greater frontal mobility of the ankle joint compared to YC shoes, which is relatively unfavourable for maintaining a stable neutral position of the ankle joint. Based on the above findings, running shoes with a full-scale carbon plate design could be a better choice for athletes who can adapt to the stiffer midsole, but sprinters with chronic ankle instability may prefer Y-shaped carbon plate designs or running shoes with relatively lower hardness.

This study employed a short-distance sprint protocol (∼10 m at 7 m/s), which may not fully represent typical competitive sprints or middle-to long-distance running scenarios. Therefore, caution should be taken when generalizing the findings beyond the tested condition. Because all participants were male sprinters, the findings may not generalize to female athletes, who often exhibit different ankle mechanics and joint laxity profiles, future research including both sexes is warranted to determine whether similar effects would be observed in female runners. Another limitation of this study is that the carbon fiber used here only differed in shape, as different production processes for carbon fiber materials can also significantly impact its mechanical properties. Future research can explore the differences brought by more types of carbon plates, curvatures, and other designs.