Successful performance in grappling combat sports (GCS) can be influenced by the fighter’s capacity to sustain high-intensity contractions of the handgrip muscles during combat. This study investigated the influence of GCS experience on the critical torque (CT), impulse above CT (W′), tolerance, and neuromuscular fatigue development during severe-intensity handgrip exercise by comparing fighters and untrained individuals. Eleven GCS fighters and twelve untrained individuals participated in three experimental sessions for handgrip muscles: (1) familiarization with the experimental procedures and strength assessment; (2) an all-out test to determine CT and W′; and (3) intermittent exercise performed in the severe-intensity domain (CT + 15%) until task failure. No significant differences were found in CT and neuromuscular fatigue between groups (p > 0.05). However, GCS fighters showed greater W′ (GCS fighters 2238.8 ± 581.2 N·m·s vs. untrained 1670.4 ± 680.6 N·m·s, p < 0.05) and exercise tolerance (GCS fighters 8.38 ± 2.93 min vs. untrained 5.36 ± 1.42 min, p < 0.05) than untrained individuals. These results suggest that long-term GCS sports training can promote increased tolerance to severe-intensity handgrip exercise and improved W′ without changes in CT or the magnitude of neuromuscular fatigue.

There is great variability in responsiveness to post-activation performance enhancement (PAPE). Factors such as greater expression of type II muscle fibers and experience with strength training are associated with greater responsiveness to PAPE. We investigated whether there is an association between markers of muscular function and morphology and responsiveness to PAPE in untrained individuals. Sixty-six active men (22 ± 2 years, 74 ± 11 kg, and 172 ± 27 cm) participated in the study. Their countermovement jump (CMJ) heights were measured before and four minutes after a pre-activation protocol consisting of five squats with a 5RM load. Isometric knee extensor peak torque (IPT), CMJ power (PO_CON), and thickness of the vastus lateralis muscle (VL_MT) of the participants were also determined in an unpotentiated condition. Change in CMJ height (ΔCMJ) following the pre-activation protocol was calculated and its associations with baseline CMJ height (CMJ_CON), PO_CON, IPT, and VL_MT were tested. Linear stepwise multiple regression models were also applied to screen for predictors of ΔCMJ among the dependent variables. No significant change (p = 0.28) in CMJ height was observed after the PA protocol (pre: 30.8 ± 5.1 cm; post: 31.0 ± 5.5 cm). No significant associations (p > 0.05) were found between ΔCMJ and IPT, VL_MT, PO_CON, and CMJ_CON (r = 0.29, 0.18, 0.09, and 0.01, respectively). Linear stepwise multiple regression analyses did not result in any significant models for ΔCMJ prediction. Although we confirmed the high individual variability in response to PA, no associations between neuromuscular performance/morphology and responsiveness to PAPE were found.

This study investigated the effect of severe‐intensity exercise on neuromuscular fatigue (NMF) and torque complexity in two muscle groups of different sizes. The NMF of 11 healthy males was assessed through maximal voluntary contractions at the beginning, every minute and at task failure during intermittent isometric exercise performed at an intensity 15% above the critical torque for knee extensors (KE) and handgrip (HG) muscles. Torque complexity was assessed using submaximal contractions from the first and last minutes of the exercise through approximate entropy (ApEn) and detrended fluctuation analysis (DFA‐α). The NMF reduced torque complexity (ApEn from 1.55 ± 0.09 to 1.25 ± 0.20, P < 0.001; DFA‐α from 1.40 ± 0.11 to 1.52 ± 0.06, P = 0.001) of the KE muscles. However, in HG muscles, the torque complexity was reduced only for DFA‐α analysis (1.01 ± 0.16 to 1.24 ± 0.16, P < 0.001). The loss of complexity was accompanied by greater central (KE −14.9 ± 12.4% × HG −7.66 ± 5.23%, P < 0.001) and peripheral fatigue (KE −63.8 ± 20.9% × HG −29.0 ± 14.5%, P < 0.001) in KE muscles than HG muscles, despite a similar decline in maximal torque production and exercise tolerance. These findings suggest that the magnitude of NMF may influence the loss of torque complexity between different muscle groups, resulting in impaired motor control ability. Furthermore, the greater impairment observed may be influenced by differences in muscle size, which could affect various physiological responses.

In 2021, heel-hook joint-locks (HHJL), effective and controversial techniques known for forcing opponents to quit, were introduced in Brazilian jiu-jitsu (BJJ) no-gi tournaments. However, the effects of these rule changes on no-gi match dynamics remain unknown. This study aimed to investigate the effects of HHJL legalization on the match dynamics of high-level male BJJ no-gi athletes. One hundred and eighty-five matches were categorized following HHJL legalization (Pre x Post) and into five subdivisions: extra-lightweight, lightweight, middleweight, heavyweight, and absolute. Post-HHJL, the number of matches ending by leg-based submission increased (Pre: 6 x Post: 19, p = 0.02), especially by HHJLs (n = 15). Minor changes were observed in time-motion analysis across combat phases. However, in heavyweight, high-intensity actions (attack-and-defense) decreased after HHJL legalization (median [first and third interquartiles]; Pre: 98s [59-112s] x Post: 47s [29-96s], p = 0.02). Moreover, total points scored were reduced in extra-lightweight (Pre: 7 [4-10] x Post: 0 [0-8], p = 0.02) and heavyweight (Pre: 8 [2-11] x Post: 2 [0-6], p = 0.01) after HHJL, while the number of applied techniques during matches were reduced in middleweight (Pre: 7 [5-8] x Post: 3 [2-6.5], p = 0.01) and heavyweight (Pre: 7 [5-10] x Post: 5 [3-7], p = 0.03), respectively. Total match duration did not change after HHJL legalization. HHJL legalization increased the occurrences of leg-based submissions. However, only minor changes were observed in the time structure of BJJ no-gi matches, with heterogeneous effects across weight divisions.

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