1. Myotonometric assessment of achilles tendon and gastrocnemius stiffness in recreationally active young adults : reliability, impact of sex, and links to linear sprintMatic Sašek, Petra Brnelić, Žiga Kozinc, 2026, izvirni znanstveni članek Opis: This study examined the relationship between passive Achilles tendon (AT) and gastrocnemius (GAS) stiffness, measured by myotonometry, and 40-m sprint performance across acceleration and maximal velocity phases, while accounting for sex differences. Twenty-one student athletes (10 males, 11 females) underwent bilateral passive stiffness assessments of the AT and GAS using MyotonPRO, followed by 40-m sprint testing with 10, 20, 30, and 40 m splits. Reliability was assessed using the intraclass correlation coefficient (ICC) and coefficient of variation (CV). Sex differences were examined with independent t-tests. Partial correlations controlling for sex were used to assess associations between passive stiffness and sprint performance. Passive stiffness and sprint variables demonstrated excellent within-session reliability (ICC = 0.95–0.99; CV < 5%). Males showed significantly greater passive GAS stiffness bilaterally (p = 0.006–0.049) and faster sprint times at 30 m (p = 0.040) and 40 m (p < 0.001), while passive AT stiffness did not differ significantly between sexes. Partial correlations indicated that greater passive AT stiffness in both legs was associated with faster sprint times at 10 m (r = -0.46 and -0.58, p = 0.008 and 0.043) and 20 m (r = -0.49 and -0.58, p = 0.008 and 0.029). No associations were observed at 30 m or 40 m, nor between passive GAS stiffness and sprint performance. Myotonometry provides reliable measures of AT and GAS stiffness. Greater passive AT stiffness is associated with faster acceleration sprint performance independent of sex.
Ključne besede: stiffness, muscle, tendon, sprint
Objavljeno v RUP: 06.04.2026; Ogledov: 119; Prenosov: 6
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2. Start detection in resisted sprinting : a validity and reliability analysis of encoder- and sensor-based methodsOskar Cvjetičanin, Matic Sašek, Živa Mesec, Nejc Šarabon, 2026, izvirni znanstveni članek Opis: This study evaluated the validity and reliability of start detection methods for determining 5-m sprint time using a resistance device with an encoder. Seventeen recreationally trained participants completed 12 resisted 5-m sprints across two sessions. Sprint start was identified using three encoder-based methods (position, velocity [MEv], and acceleration), a rear-foot release sensor and hip-marker kinematics (KIN) as a proxy for forward center-of-mass displacement. Reliability was evaluated using intraclass correlation coefficient (ICC), coefficient of variation (CV), typical error (TE), standard error of measurement (SEM), and minimal detectable change (MDC), while agreement was examined using Pearson correlations and Bland-Altman analysis. All methods showed moderate to excellent reliability (ICC = 0.54–0.93; CV ≤ 11.1%) and strong agreement with KIN (r = 0.90–0.94). MEv showed the smallest bias (−0.00 ± 0.07 s) and narrowest 95% limits of agreement, and is therefore preferred for sprint start detection in practical settings.
Ključne besede: resisted sprinting, sprint start, encoder, performance monitorin
Objavljeno v RUP: 26.03.2026; Ogledov: 244; Prenosov: 11
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3. Within-session reliability and comparison in resisted sprint performance with the 1080 Sprint between belt and harness attachment pointsMatic Sašek, Nicola Reiner Volk, Nejc Šarabon, 2025, izvirni znanstveni članek Opis: The application of resistance over the shoulder or hips during resisted sprints could influence performance outcomes but has not been thoroughly investigated. This study examined the within-session reliability of sprint performance measures and compared the outcomes of 1080 Sprint device between belt (hips) and harness (shoulders) attachment. Twelve student-athletes completed three 20 m sprints with resistance equivalent to 25% of body mass (14.0 to 24.7 kg). Sprint split times (5 m, 10 m, 15 m, 20 m), peak velocity, and distance at peak velocity were recorded with 1080 Sprint. Within-session reliability was assessed using intraclass correlation coefficients (ICC3.1) and coefficients of variation (CV), while differences in performance were analysed using paired t-tests and effect sizes (ES). Reliability was excellent for all variables (ICC3.1≥ 0.93; CV ≤ 3.08 %) except distance at peak velocity, which showed poor reliability (ICC3.1≥ 0.32; CV ≥ 17.2 %). Sprint times and peak velocity were faster with the belt attachment (ES ≥ 0.93), while peak velocity was reached earlier with the harness attachment (ES = 0.65). Both attachment points provided reliable measurements, but the belt consistently resulted in faster 20 m sprint performance. Coaches and practitioners should consider these differences when assessing resisted sprint performance or prescribing training to ensure consistent and individualized loading strategies
Ključne besede: resisted sprint, resistance, sprint performance, speed assessment
Objavljeno v RUP: 30.12.2025; Ogledov: 475; Prenosov: 0
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4. Relationship between curvilinear sprint performance, hip strength, jump performance and reactive strength in elite youth soccer playersAžbe Ribič, Matic Sešek, 2025, izvirni znanstveni članek Opis: The aim of this study was to investigate the relationships between hip strength, vertical jump performance, reactive strength index, and curvilinear sprint (CS) performance and to compare these variables between different playing positions in youth soccer players. Thirty-four players completed two test sessions. Hip adduction and abduction strength was measured using a hand-held dynamometer. A force plate was used to measure the height of the countermovement jump and the drop jump as well as the contact time, from which the modified reactive strength index and the reactive strength index (RSI) were calculated. The CS was tested on the penalty arch of a soccer pitch. One way ANOVA was used to test the effects of playing position whereas the Pearson's r was used to test the relationship between variables. There were no significant differences in the measured variables between defenders, midfielders and attackers (p≥ .140). Along with RSI, which showed significant moderate to large correlations (r = -0.39 to -0.59), hip abduction strength was also significantly associated with CS split times (r = -0.36 to -0.38). Results emphasize the relevance of ankle reactive strength and hip strength for CS performance and supports the inclusion of ankle and hip-specific strength exercises in the training of youth soccer players.
Ključne besede: curvilinear sprint, hip strength, reactive strength, vertical jump, soccer
Objavljeno v RUP: 12.12.2025; Ogledov: 478; Prenosov: 5
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6. Curvilinear sprint acceleration-speed profile in youth soccer players is constrained by tighter radii and sprinting side dominance : aAžbe Ribič, Darjan Smajla, Oskar Cvjetičanin, Matic Sašek, 2025, izvirni znanstveni članek Opis: This study investigated how the acceleration-speed profile (ASP) of the weaker and stronger side changes at different radii. Twenty male youth soccer players completed 30 m linear and curvilinear sprints (12.15, 11.15, 9.15, 7.15, and 6.15 m radius) in three training sessions. Sprint speed and acceleration over time and distance were recorded using a GNSS device. The maximum theoretical speed (S0), the acceleration (A0), slope of the ASP (ASslope), the area under the ASslope (ASParea), the acceleration at a sprint speed of 3 m/s (A3), and the curvilinear sprint deficit (ASPdeficit) of the individual sprints were analyzed. The effects of side, radius, and their interaction were evaluated with 2 × 5 ANOVA and the post hoc tests. A significant effect of radius and side was observed for all variables (F ≥ 3.50, p ≤ 0.037, η2 ≥ 0.15). The ASParea and S0 decreased at tighter radii. The A3 and A0 remained relatively unchanged, resulting in a steeper ASslope, and a larger ASPdeficit. At the same radius, the weaker side CS had a smaller ASParea, S0, A3, and a larger ASPdeficit. The ASP of the curvilinear sprint in youth soccer players is side-dependent at both ends (acceleration and top speed), while radii mainly affect late acceleration and top speed performance. These observations should be considered when adapting soccer players’ sprint training and monitoring external load based on acceleration.
Ključne besede: curvilinear sprint, acceleration-speed profile, sprint performance, soccer
Objavljeno v RUP: 08.09.2025; Ogledov: 723; Prenosov: 10
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