Yang, Z, Peng, F, Lin, J, Zeng, Y, Su, Y, Shi, Y, and Li, W. Acute physiological and perceptual responses to decreasing-distance versus constant-distance HIIT in elite male speed skaters. J Strength Cond Res XX(X): 000–000, 2026—This study investigated the acute effects of a decreasing-distance high-intensity interval training (D-HIIT) strategy vs. a constant-distance HIIT (C-HIIT) protocol on endurance performance, physiological responses, and rating of perceived exertion (RPE) in elite speed skaters. Eighteen Tier-4 male speed skaters were randomized into D-HIIT (1,600, 1,200, 1,200, and 800 m) or C-HIIT (4 × 1,200 m) groups, matched for total distance (4,800 m). Velocity drop rate (VDR), heart rate (HR), blood lactate (BLa), and RPE were monitored. D-HIIT resulted in a significantly shorter total time (381.89 ± 3.55 seconds vs. 393.11 ± 2.93 seconds, p < 0.001) and lower VDR (2.10 ± 0.27% vs. 3.72 ± 0.24%; p < 0.001). D-HIIT also elicited higher peak BLa in the final bout (11.81 ± 0.29 vs. 9.31 ± 0.29 mmol·L ⁻¹ , p < 0.001), while terminal RPE was lower than that in C-HIIT (17.22 ± 0.67 vs. 18.22 ± 1.13, p < 0.05). D-HIIT was associated with faster completion, lower velocity drop, higher HR and BLa responses, and lower terminal RPE than C-HIIT under matched external distance. Because RPE did not show a significant Group × Bout interaction, the perceptual findings should be interpreted cautiously. Decreasing-distance high-intensity interval training may be considered as an acute session format for imposing a high physiological stimulus while maintaining manageable perceived exertion, but its mechanisms and long-term training effects require further investigation.

Background: Upper-limb strength characteristics are considered important determinants of shooting stability in precision sports; however, the specific relationships between upper-limb strength variables and shooting performance in elite air pistol athletes remain insufficiently understood. Therefore, this study aimed to investigate the associations between upper-limb-specific strength characteristics and shooting performance in elite air pistol shooters. Methods: A prospective observational cohort study was conducted using a purposive total population sample from an elite training camp. Isometric peak force and rate of force development of nine upper-limb muscle actions, including handgrip, elbow flexion and extension, and shoulder joint movements, were assessed using a Vald Dynamo handheld dynamometer. Official scores from an international selection competition were used as indicators of shooting performance. Ridge regression analysis was applied to examine the relationships between strength variables and shooting performance while addressing multicollinearity among predictors. Results: Twenty-four elite air pistol athletes at national master level or above were recruited. Ridge regression revealed distinct coefficient patterns between upper-limb task-specific strength characteristics and total shooting score. After within-sex standardization of strength predictors, larger positive ridge coefficients were observed for handgrip RFD, elbow flexion peak force, shoulder external rotation RFD, elbow extension peak force, and selected shoulder variables, whereas negative coefficients were observed for shoulder internal rotation RFD, handgrip peak force, shoulder extension RFD, elbow extension RFD, and selected shoulder variables. These findings suggest that shooting performance is associated with the balance and coordination of task-specific upper-limb strength characteristics rather than maximal strength alone. Conclusions: These findings suggest that coordinated upper-limb task-specific strength balance is associated with shooting performance in elite air pistol athletes. These findings may help inform individualized conditioning and monitoring strategies; however, longitudinal intervention studies are needed to determine whether modifying upper-limb strength balance can improve shooting outcomes.

This study investigated the neural timing control characteristics of countermovement jumps between elite athletes and nonathletes using muscle synergy theory. Twenty male participants (high-level group [HLG, N = 10] and untrained group [UG, N = 10]) performed the countermovement jump while surface electromyography from eight lower limb muscles and three-dimensional force plate data were recorded. Nonnegative matrix factorization extracted three muscle synergy modules, and bootstrap resampling with bias-corrected 95% confidence intervals (CIs) analyzed temporal parameters. Results demonstrated: (a) HLG achieved significantly greater jump height (95% CI: [−0.139, −0.026]); (b) HLG exhibited delayed activation onset (95% CI: [−0.227, −0.015]), peak timing (95% CI: [−0.300, −0.028]), and offset (95% CI: [−0.216, −0.014]) in Synergy module 1, delayed onset (95% CI: [−0.225, −0.054]) and offset (95% CI: [−0.224, −0.072]) in Synergy module 2, and delayed offset in Synergy module 3 (95% CI: [−0.197, −0.017]); and (c) HLG showed narrower full width at half maximum in Synergy module 1 (95% CI: [0.009, 0.094]), with no group differences in amplitude parameters. These findings suggest that, compared with UG, HLG exhibit delayed synergy activation timing during the countermovement jump. This temporal pattern may be associated with more effective use of the eccentric phase and more coordinated interjoint timing during propulsion.

Background: Upper limb strength characteristics are considered important determinants of shooting stability in precision sports; however, the specific relationships between upper limb strength variables and shooting performance in elite air pistol athletes remain insufficiently understood. Therefore, this study aimed to investigate the associations between upper limb specific strength characteristics and shooting performance in elite air pistol shooters. Methods: A prospective observational cohort study was conducted using a purposive total population sample from an elite training camp. Isometric peak force and rate of force development of nine upper limb muscle actions, including handgrip, elbow flexion and extension, and shoulder joint movements, were assessed using a Vald Dynamo handheld dynamometer. Official scores from an international selection competition were used as indicators of shooting performance. Ridge regression analysis was applied to examine the relationships between strength variables and shooting performance while addressing multicollinearity among predictors. Results: Twenty four elite air pistol athletes at national master level or above were recruited. Shooting performance demonstrated significant positive associations with handgrip peak force, handgrip rate of force development, elbow flexion peak force, elbow extension peak force, shoulder abduction peak force, shoulder internal rotation peak force, and elbow extension rate of force development. Significant negative associations were observed between shooting performance and shoulder flexion peak force, shoulder adduction peak force, shoulder external rotation peak force, shoulder extension rate of force development, shoulder adduction rate of force development, and shoulder internal rotation rate of force development. Conclusions: These findings indicate that a coordinated balance of upper limb specific strength is a key factor influencing shooting performance in elite air pistol athletes. Appropriate development of task specific muscle strength may enhance gun holding stability and trigger control, whereas excessive activation of antagonistic muscle groups may adversely affect shooting accuracy.