Eccentric quasi-isometric (EQI) contractions combine isometric holding with subsequent eccentric (ECC) lengthening. Although EQI exercise has gained attention, its chronic effects remain unclear. This study compared morphological and functional adaptations to EQI and ECC resistance exercise. Forty-eight healthy, regularly trained adult participants were randomly allocated (sex-stratified) to EQI, ECC, or control groups (n = 16 per group; age 22.91 ± 4.70). The intervention groups completed a six-week training program with matched load and time under tension. Outcomes assessed pre- and post-intervention included Achilles tendon properties, gastrocnemius architecture, ankle range of motion, and plantar flexor strength. Both EQI and ECC training increased Achilles tendon thickness, gastrocnemius fascicle length and muscle thickness, and lateral gastrocnemius pennation angle compared to control (all p ≤ 0.001; η2 = 0.53-0.79), with no differences between protocols (p = 0.227-0.965). Ankle dorsiflexion (open and closed kinetic chain) and concentric, ECC, and isometric strength improved in both intervention groups compared to control (p ≤ 0.019; η2 = 0.33-0.77), without between-group differences (p = 0.561-0.976). Only ECC training increased EQI time under tension and torque impulse (p = 0.012-0.020), while tendon stiffness, medial gastrocnemius pennation angle, and EQI angular velocity did not change (p ≥ 0.065). EQI and ECC training produced comparable improvements in muscle–tendon morphology, strength, and ankle dorsiflexion when load and time under tension were matched, while EQI training was associated with lower muscle soreness.
Cardiorespiratory fitness (CRF), commonly assessed using maximal oxygen uptake (VO2max), is an important health marker in children and adolescents. We compared the effects of different exercise types and examined dose-response associations with CRF. PubMed, Embase, the Cochrane Library, and Web of Science were searched from inception to June 2026 for randomized controlled trials involving participants younger than 18 years. All analyses were conducted after the final search. Interventions were classified as high-intensity interval training (HIIT), sprint interval training (SIT), high-intensity aerobic exercise (HAE), moderate-intensity aerobic exercise (MAE), combined exercise (CE), or resistance exercise (RE). We performed an arm-based Bayesian multilevel random-effects network meta-analysis and Bayesian meta-regression. Fifty-two trials involving 4, 308 participants were included. Compared with the control group, HIIT had the largest estimated improvement in CRF (mean difference [MD] = 2.50, 95% credible interval [CrI]: 1.46 to 3.51), followed by SIT (MD = 2.05, 95% CrI: 0.85 to 3.22), CE (MD = 1.95, 95% CrI: 0.87 to 2.98), and HAE (MD = 1.25, 95% CrI: 0.09 to 2.41). The intervals for MAE and RE included the null value. Dose-response analyses showed the highest posterior mean effects around 1,100 METy-min/week, 40 min/session, and a METy-based intensity of approximately 8.5 METy, although the weekly-dose estimate remained imprecise. Exercise interventions were associated with improved CRF in children and adolescents, with HIIT and SIT ranking most favorably. Study-level analyses suggested favorable patterns around 1,100 METy-min/week, 40 min/session, and 8.5 METy, although these should not be considered precise optimal prescriptions.
This randomized crossover study compared surface electromyographic (sEMG) amplitude across cadence-defined lifting and lowering analytical intervals under four front lat pulldown attachment conditions in resistance-trained men. Sixteen participants performed the exercise with a straight bar, wide V-shaped handle, cambered bar, and rope. Each condition was performed at 70% of its attachment-specific 1-repetition maximum using a metronome-prescribed nominal 2-second lifting and 2-second lowering cadence and standardized grip-width criteria. sEMG was recorded from the latissimus dorsi, middle trapezius, posterior deltoid, biceps brachii, and triceps brachii. Normalized root mean square amplitudes were analyzed with repetition-level linear mixed-effects models, and sensitivity analyses were used to examine robustness. The most consistent attachment-related findings were greater biceps brachii sEMG amplitude in the wide V-shaped handle condition, particularly in the lifting analytical interval, and greater posterior deltoid sEMG amplitude in the rope than cambered-bar condition. Middle trapezius sEMG amplitude was greater in the cadence-defined lowering analytical interval than in the lifting interval. Specifically, the rope exceeded the cambered bar for posterior deltoid sEMG amplitude (mean difference = 8.0 %MVIC, 95% CI = 4.1 to 11.9; p = 0.002), and the wide V-shaped handle showed greater biceps brachii sEMG amplitude in the lifting analytical interval than the straight bar, cambered bar, and rope (mean differences = 11.0 to 15.7 %MVIC; all p < 0.001). Middle trapezius sEMG amplitude was greater in the lowering analytical interval than in the lifting analytical interval (mean difference = 6.2 %MVIC, 95% CI = 3.3 to 9.1; p < 0.001). No consistent between-condition difference was found for latissimus dorsi sEMG amplitude; a small attachment-by-phase interaction in the primary model was attenuated in complete-case sensitivity analysis. Because relative intensity was standardized to attachment-specific 1RM, absolute loads differed among conditions. The results therefore describe differences among attachment-specific relative-load conditions and should not be attributed solely to attachment geometry. The lifting and lowering labels refer to cadence-defined analytical intervals rather than mechanically synchronized phase boundaries, and acute sEMG findings should not be interpreted as evidence of longer-term hypertrophy or strength adaptations.
The purpose of this study was to compare acute mechanical output and immediate post-exercise jump responses among percentage-based training (PBT), repetitions in reserve (RIR), and velocity-based training (VBT) during the back-squat exercise in trained sprinters. Eighteen trained male 100-m sprinters completed all three conditions in randomized order using a within-participant crossover design, with at least 72 h between trials. Each condition began at 80% of one-repetition maximum and comprised of five sets with a maximum of five repetitions per set. Bilateral force plates recorded vertical ground-reaction force during squatting and during pre- and post-exercise countermovement jump (CMJ) and squat jump (SJ) tests. Completed repetitions averaged 25.00, 25.00, and 24.06 per session under PBT, RIR, and VBT, respectively; session volume loads also differed among protocols. No statistically significant overall condition effects were detected for relative peak vertical force (p = 0.348), mean positive vertical impulse (p = 0.262), CMJ jump height (p = 0.969), CMJ modified reactive strength index (p = 0.894), or SJ jump height (p = 0.740). The present study found that VBT resulted in fewer completed repetitions and lower session volume load than PBT and RIR. No significant between-protocol differences were detected in session-level mechanical output or immediate postexercise jump responses.
Although regular physical activity is recommended for osteoarthritis (OA) prevention, many adults fail to exercise consistently due to time constraints. We evaluated the association between the "weekend warrior" (WW) pattern, defined as accumulating the recommended amount of physical activity within one or two days per week, and incident OA. This prospective cohort study used data from the UK Biobank accelerometer substudy. A total of 83, 386 participants with valid 7-day wrist-worn accelerometer data were included. Participants were classified as inactive (< 150 min/week of moderate-to-vigorous physical activity [MVPA]), weekend warriors ( >= 150 min/week with >= 50% of MVPA accumulated within 1-2 days), or regularly active ( >= 150 min/week with >= 50% distributed across > 2 days). Sensitivity analyses were additionally conducted using progressively stricter MVPA concentration thresholds ranging from >= 55% to >= 95%. Incident OA was identified through linked health records. Cox proportional hazards models were applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Over a median follow-up of 7.9 years, 8, 130 incident OA cases were identified. Compared with inactive participants, both regularly active and weekend warrior patterns were associated with lower OA risk in fully adjusted models (HR = 0.889, 95% CI: 0.835-0.946, HR = 0.894, 95% CI: 0.850-0.941, respectively), and these inverse associations remained stable when using stricter MVPA concentration thresholds ranging from >= 55% to >= 90%. In contrast, compared with regularly active participants, weekend warrior participants did not show a statistically significant difference in OA risk (HR, 1.031; 95% CI, 0.968-1.099), even after further adjustment for total MVPA volume. Accumulating guideline-recommended MVPA within one to two days per week was associated with a lower risk of incident OA, comparable to regularly distributed physical activity. The weekend warrior pattern may represent a practical option for OA prevention among time-constrained adults.
