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Post-activation performance enhancement (PAPE) is often attributed to elevated neural drive, yet neuromuscular and mechanical responses are rarely tracked concurrently. This study examined whether the two scale proportionally over the 1–4 min following a conditioning activity, with a maximal countermovement jump (CMJ) at each minute. Twenty-two male youth soccer players performed a baseline CMJ, a conditioning activity, then a CMJ at each minute to 4 min, with bilateral vastus lateralis and semitendinosus EMG (fixed 300 ms pre-take-off window) and jump height recorded simultaneously. Jump height varied across time, owing to a transient decrease at 1 min (−1.41 cm); from 2 min onward, it was equivalent to baseline (TOST, ±1.5 cm, all p ≤ 0.005). The composite EMG index instead rose almost exclusively at 4 min (d_z = 3.22), as did each channel individually, producing a signal × time interaction (F(3, 63) = 108.85, p < 0.001) and a decoupling index of +120.4%; the within-participant association between the two measures was weak (rrm = 0.11). Surface EMG amplitude can therefore rise sharply where mechanical output is equivalent to baseline within ±1.5 cm, and cannot be assumed to index a proportional mechanical gain. With no control condition, the observed time course reflects the conditioning activity together with the intervening maximal jumps.

Leg-spring hysteresis, the mechanical energy dissipated within the force–length loop during ground contact, is a whole-limb, indirect indicator of stretch-shortening cycle (SSC) function. Whether international-level track-and-field and club-level multi-sport athletes differ in hysteresis responses to drop height, and whether hysteresis is associated with jump height, remains unclear. Here, 40 athletes (15 international-level, 25 club-level) performed bilateral (BLJ), dominant-leg (DOM), and non-dominant-leg (NDOM) drop jumps from 0.26 to 0.42 m. Hysteresis and jump height were computed from three-dimensional kinematics (500 Hz) and ground reaction forces. Group × drop-height interactions were significant for hysteresis in all conditions (partial eta-squared, η²p = 0.647, 0.507, 0.466; p < 0.001): international-level athletes became increasingly negative (net active energy contribution) at 0.42 m, whereas club-level athletes became positive (net dissipation). Between-group differences at 0.42 m were large (Cohen’s d = −1.73, DOM; −1.95, NDOM); jump height was also higher in international-level athletes (d = 1.14–1.77). Pooled, hysteresis was associated with jump height (coefficient of determination, R² = 0.44–0.60), although caliber differences inflate this estimate, and within-group associations were weaker. Hysteresis discriminated reactive-jumping capacity beyond jump height alone; because competitive level was confounded with sport discipline and sex, these differences should not be attributed to caliber per se.

Leg-spring hysteresis quantifies the mechanical energy dissipated within the force–length loop during ground contact and serves as a proxy for stretch-shortening cycle (SSC) efficiency. Whether international-level track-and-field athletes and club-level multi-sport athletes differ in their hysteresis responses to increasing drop height, and whether hysteresis predicts jump height, remains unclear. Forty athletes (15 international-level, 25 club-level) performed bilateral (BLJ), dominant-leg (DOM), and non-dominant-leg (NDOM) drop jumps from 0.26 m and 0.42 m. Three-dimensional kinematics (500 Hz) and ground reaction forces were used to compute leg-spring stiffness, hysteresis, and jump height. Significant group × drop-height interactions emerged for hysteresis in all three conditions (η²p = 0.647, 0.507, 0.466; p < .001): international-level athletes became increasingly negative (greater SSC enhancement) at 0.42 m, whereas club-level athletes showed positive hysteresis (net dissipation). Between-group hysteresis differences at 0.42 m were large (DOM d = −1.73; NDOM d = −1.95), and jump height was consistently higher in international-level athletes (d = 1.14–1.77). Pooled across groups, hysteresis was associated with jump height (R² = 0.44–0.60), although this estimate is inflated by caliber differences and within-group associations were moderate and condition-dependent. Leg-spring hysteresis is a mechanically meaningful and practically relevant discriminator of reactive-jumping capacity.

The high incidence of anterior cruciate ligament (ACL) injuries in female soccer players persists despite widespread preventive interventions. Traditional screening relies heavily on isokinetic torque ratios to assess mechanical joint stability; however, this approach often fails to capture the temporal dynamics of sensorimotor control. Wearable wireless electromyography (sEMG) provides a viable modality to assess these neuromuscular latency deficits. Twenty-one female soccer players (age: 17.60 ± 0.87 years) underwent reciprocal concentric isokinetic testing at 60°/s, 180°/s, and 240°/s. The hamstring-quadriceps torque ratio was measured via an isokinetic dynamometer and normalized to body weight. Simultaneously, neuromuscular latency was acquired using a wearable wireless sEMG system (BTS FreeEMG) on the vastus lateralis and semitendinosus. Neuromuscular latency was quantified using a computerized threshold algorithm to determine the agonist-antagonist asynchrony. A significant main effect of angular velocity was observed on neuromuscular latency (p < 0.05), which decreased with increasing velocity, reflecting feed-forward adaptation. A positive correlation emerged between the mechanical H/Q torque ratio and neuromuscular latency, most notably at 60°/s (r = 0.792) and 240°/s (r = 0.681). This indicates a paradoxical latency-strength mismatch, in which players with more favourable H/Q torque ratios exhibit significantly delayed neuromuscular reflexive responses. Static mechanical symmetry does not guarantee dynamic temporal efficiency. The identified latency-strength mismatch suggests that standard dynamometry may mask critical sensorimotor deficits. The integration of wearable wireless sEMG technology into injury risk screening is essential to capture these temporal asymmetries and ensure that mechanical capacity is matched by rapid neural drive.

This study examined the acute effects of four structured warm-up protocols “FIFA 11+”, PEP, HarmoKnee, and a “dynamic warm-up” on p

Background: The purpose of this study was to investigate the effects of different loads used in post-activation potentiation (PAP) exercises on the vertical jump and sprint performance of young amateur soccer players. Materials and methods: Twelve young amateur soccer players (age: 16.3 ± 1.2 years; height: 172.6 ± 3.88 cm; body weight: 63.2 ± 6.7 kg; training experience: 2.3 ± 1.4 years) participated voluntarily. The half squat exercise was performed in unloaded conditions and at three different intensities (L1:80%, L2: 90%, and L3: 100% of one-repetition maximum [1RM]), and its effects on players' countermovement jump (CMJ) and 30 m sprint (with 10 m split times) performance after four min recovery duration were examined. Results: The results showed that the players were significantly better in CMJ, 10-, and 30-m sprint performance in the L1 condition compared to the unloaded condition (p < 0.05). Conclusions: It is recommended that coaches and sports scientists increase the PAP effect following heavy resistance training. 80% of 1RM load was more appropriate than 90% or 100% of 1RM in young amateur soccer players.

Bu araştırmanın amacı sporcuların dikey sıçrama performansını ölçmek amacıyla kullanılan My Jump Lab (MJL) uygulamasının geçerlilik ve güvenirliğinin belirlenmesidir. Araştırmaya, amatör seviyede iki farklı branşta (futbol: 28; tenis: 12) düzenli olarak antrenman yapan 21 erkek ve 19 kadın olmak üzere toplam 40 gönüllü sporcu katılmıştır (yaş: 21,95±2,23 yıl; boy: 170,74±10,28 cm; vücut ağırlığı: 66,50±12,35 kg). Araştırma kapsamında sıçrama performansını değerlendirmek için dikey sıçrama (DS) testi kullanılmıştır. Her ölçüm öncesinde beş dakikalık standart bir ısınma protokolü uygulanmıştır. Her ölçüm için iki kez DS testi yaptırılmıştır. Ölçümler arasında iki dakikalık dinleme süresi verilmiş olup sporcuların en iyi performansı kaydedilmiştir. Bu esnada MJL uygulamasının geçerlik ve güvenirlik analizleri için akıllı bir cep telefonuna (14 Promax, Apple, ABD) kayıtlı MJL uygulaması ve Opto Jump fotoelektrik hücre sistemi (Opto Jump Next, Microgate, İtalya) kullanılmıştır. Bu iki sistemde eş zamanlı olarak çalıştırılmış ve kullanılmıştır. Ölçümler 3 farklı ölçüm gününde randomize bir şekilde 24 saat arayla gerçekleştirilmiştir. İstatistiki analiz yöntemlerinden, geçerliliği test etmek için ölçüt geçerliği tekniği esas alınırken, güvenirliği test etmek için test-tekrar test yöntemi kullanılmıştır. MJL uygulamasının güvenirlik testi için sınıf içi korelasyon katsayısı (ICC) kullanılırken ölçüt geçerliğini sınamak için Pearson korelasyon katsayısı incelenmiştir. Her iki ölçme aracı arasındaki test puanlarının farklılığı tespit etmek için ilişkili örneklemlerde t-testi kullanılmıştır. Son olarak, MJL uygulaması için iki ölçüm yöntemi arasındaki uyumu görsel olarak değerlendirmek amacıyla DS sıçrama yüksekliği değerleri Bland-Altman tekniği ile incelenmiştir. Araştırma bulgularına göre her iki uygulama için DS yüksekliği değerlerinin güvenirlik katsayısının yüksek düzeyde olduğu tespit edilmiştir. Her iki ölçüm yöntemi arasındaki farkın t-testi sonuçlarına göre anlamlı düzeyde olmadığı belirlenmiştir (p>0.05). Son olarak Bland-Altman analizi sonuçları da her iki ölçme yöntemi arasında sistematik bir hata olmadığını göstermiştir. Sonuç olarak MJL uygulaması üzerinde yapılan geçerlik analizleri, güvenilir ve kabul edilebilir nitelikte sonuçlar ortaya koyduğu tespit edilmiştir.

This study aimed to compare force plate, motion analysis, and mobile application methods for calculating vertical jump height. Twenty-nine male college students (age: 22.4 ± 1.0 years; height: 178.1 ± 6.2cm; body weight: 71.2 ± 8.0 kg) voluntarily participated in the study. Two countermovement jumps (CMJ) with 1-minute intervals on a force platform (BERTEC 4060-10) were performed. The countermovement jump performances were captured using an iPhone 11 (Apple Inc., USA). The experimental setup involved using three high-speed cameras, specifically the My Jump 2 and SIMI Motion 7.5. Obtained results from hip displacement (HD) data with motion analysis system showed that participants had significantly lower vertical jump height calculated from motion capture (p = 0.01; -8.3 ± 3.86, 95%CI; MyJump2-SIMI_HD = 1.24/3.30). It was also found that calculations from left and right foot displacement were higher than My Jump 2 results (95%CI; MyJump2-SIMI_RF = 0.66/2.93) and 95%CI (MyJump2-SIMI_LF) = (-0.63/2.65). In contrast, force plate calculations, known as the gold standard in the literature, were very similar to My Jump (95%CI; MyJumpII-FP) = (2.38/4.01). The findings indicate that the My Jump 2, used for assessing vertical jump height, may be a reliable alternative for determining vertical jump height instead of setting up gold standard methods. Individuals' athletic performance abilities and birth, gender, and sports preferences should be considered. Finally, when coaches or sports scientists intend to measure CMJ, My Jump 2 application can be recommended as a laboratory application as well as a practical and valid measurement method, especially for field applications.