European Journal of Applied Physiology最新文献

Objective: This study investigates the impact of plyometric training on age-related lower limb explosive strength in male adolescents and its effectiveness in female adolescents.

Methods: A thorough search was conducted across five databases from their inception until September 20, 2024. Study quality was assessed using the Cochrane Risk Assessment Tool, and data analysis was performed with Stata 15 software.

Results: Plyometric training positively affected countermovement jump (CMJ) (MD = 2.90 cm, 95% CI (2.35, 3.45)), squat jump (SJ) (MD = 2.57 cm, 95% CI (1.69, 3.44)), and 20-m sprint performance (MD = - 0.09 s, 95% CI (- 0.14, - 0.05)). Subgroup analysis revealed varying improvements across age stages. In CMJ, the early adolescence (EA) group (MD = 2.57 cm, 95% CI (1.74, 3.40)), mid-adolescence (MA) group (MD = 3.04 cm, 95% CI (2.30, 3.79)), and post-adolescence (PA) group (MD = 3.89 cm, 95% CI (1.96, 5.81)) showed progressive enhancement. The MA group exhibited superior improvements in SJ (MD = 3.78 cm, 95% CI (2.19, 5.36)) and 20-m sprint (MD = - 0.11 s, 95% CI (- 0.18, - 0.05)) compared to the EA group (SJ: MD = 2.10 cm, 95% CI (1.43, 2.77); sprint: MD = - 0.06 s, 95% CI (- 0.11, - 0.01)). The PA group showed no significant improvements (SJ: MD = 1.31 cm, 95% CI (- 1.05, 3.67); sprint: MD = - 0.27 s, 95% CI (- 0.61, 0.07)). For female adolescents, plyometric training effectively improved CMJ (MD = 2.55 cm, 95% CI (1.43, 3.66)), SJ (MD = 2.33 cm, 95% CI (1.36, 3.31)), and 20-m sprint performance (MD = - 0.22 s, 95% CI (- 0.33, - 0.12)).

Conclusion: Plyometric training significantly enhances lower limb explosive strength in both male and female adolescents, with age-dependent effects for male adolescents. The greatest improvement in CMJ was observed in the PA stage, followed by the MA stage, while the EA stage showed the least. The MA stage exhibited the best improvements in SJ and sprint performance.

Trail registry: The study has been registered in the International Prospective Register of Systematic Reviews (PROSPERO: CRD42023406914).

Purpose: To compare strength and muscle mass development between conventional resistance training (RT) and a combined resistance training with neuromuscular electrical stimulation group (RT + NMES).

Methods: Searches of EBSCO, GoogleScholar, PubMed, and ResearchGate were conducted for studies that met the inclusion criteria of being a randomized controlled trial comparing RT in isolation with NMES and RT being done simultaneously. Effect sizes were calculated as the standard mean difference (SMD) and meta-analyses were computed using random effects models. Thirteen studies were included in the analyses.

Results: When comparing strength gain, there was a favorable effect towards superimposed training (SMD: 0.31; 95% CI 0.13-0.49; p = 0.02; I² = 73.05%) with similar results seen for muscle mass (SMD: 0.26; 95% CI 0.04-0.49; p = 0.02; I² = 21.45%).

Conclusion: Use of NMES during RT results in greater gains in strength and muscle mass compared to RT performed in isolation. Incorporation of NMES into RT protocols may represent a more effective strategy to improve muscle strength and muscle mass. Future studies should explore whether use of NMES concurrently with RT may have additive effects on metabolic and/or cardiovascular health.

Purpose: With limited studies exploring the dose-response of caffeine consumption on repeated sprint ability in hypoxia, this study aimed to determine the optimal caffeine dose (low, moderate or high) during repeated sprints in hypoxia to exhaustion.

Methods: On separate visits, twelve active males randomly performed four experimental trials in normobaric hypoxia (inspired oxygen fraction: 16.5 ± 0.2%). Participants ingested placebo (PLA) or caffeine capsules (3, 6 or 9 mg/kg or LOW, MOD and HIGH, respectively) 1 h before exercise and then underwent a repeated cycling sprint test (10 s sprint/20 s active recovery) to exhaustion. Total sprint number and work done, peak and mean power output, blood lactate concentration, cardiorespiratory and perceptual responses were recorded.

Results: Total sprint number was greater in MOD and HIGH compared to PLA (20 ± 7 and 18 ± 8 vs. 13 ± 4; all P < 0.05), with MOD also higher than LOW (15 ± 6; P = 0.02). Total work done was greater in MOD (111 ± 40 kJ) and HIGH (100 ± 35 kJ) compared to LOW (83 ± 29 kJ) and PLA (76 ± 25 kJ) (all P < 0.05). However, there were no significant differences in total sprint number or total work done between MOD and HIGH (all P > 0.05). Blood lactate concentration was higher in both MOD and HIGH compared to PLA (all P < 0.05). However, peak and mean power outputs, fatigue index, and ratings of perceived exertion did not differ across different caffeine dosages (all P > 0.05).

Conclusion: A moderate dose of caffeine (6 mg/kg) is the optimal amount for enhancing repeated cycling sprint ability when compared to low and high doses in moderate normobaric hypoxia.

Purpose: Fat free mass (FFM) is considered the metabolically active component of human body and is positively associated with maximal oxygen uptake ( ${\text{VO}}_2\text{max}$ ). However, FFM is composed of metabolically active and inactive subcomponents whose proportion can vary depending on body composition and clinical condition, possibly affecting such association. Although it is known that in facioscapulohumeral dystrophy (FSHD) peculiar changes in body composition occur, it is unclear whether there are alterations in FFM composition and, if so, whether such alterations affect the association towards ${\text{VO}}_2\text{max}$ compared to healthy subjects (HS).

Methods: To address this issue, 27 FSHD patients (mean age 37.3; 9 female) and 27 sex and age matched HS, underwent an assessment of ${\text{VO}}_2\text{max}$ by cardiopulmonary exercise tests (CPET) and body composition, with reference to FFM and its subcomponents, by bioimpedance analysis.

Results: In between-groups comparison, patients showed lower amounts of body cell mass (BCM) and intracellular water (ICW) which reflect in lower BCM/FFM ratio and higher extracellular to intracellular water ratio (ECW/ICW). Patients' ${\text{VO}}_2\text{max}$ was lower than HS and, even if with lower associative values than HS, correlated with FFM and BCM, while BCM/FFM and ECW/ICW ratios associations were observed only in HS.

Conclusion: FSHD patients showed lower amount of BCM and ICW. BCM resulted as the parameter with the highest associative value with VO2max in both groups. Since ${\text{VO}}_2\text{max}$ is associated with functional ability in dystrophic patients, BCM, rather than FFM, could be an additional body composition-based clinical stratification factor.

Purpose: Central arterial stiffness, a predictor of cardiovascular risk, attenuates with endurance-exercise in ageing populations. However, in young individuals, this effect is inconsistent and emerging evidence suggests resistance-exercise may increase arterial stiffness. Two-dimensional (2D)-Strain imaging of the common carotid artery (CCA) is more sensitive at detecting endurance-training induced alterations in CCA stiffness than conventional methods, but has not been used to examine CCA stiffness in young resistance-trained individuals. Therefore, we compared CCA 2D-Strain parameters at rest, during acute exercise and recovery between resistance-trained, endurance-trained, and untrained young men.

Methods: Short-axis CCA ultrasound images were obtained from 12 endurance-trained [27yrs (95%CI; 24-29)], 14 resistance-trained [24yrs (23-26)] and 12 untrained [23yrs (22-24] men at rest, during isometric handgrip (IHG) exercise and recovery. 2D-Strain analysis quantified CCA peak circumferential strain (PCS) and systolic (S-SR) and diastolic (D-SR) strain rates. Conventional stiffness indices included aortic pulse-wave velocity, CCA β-stiffness (β₁) and Petersons elastic modulus (E_p).

Results: Resting conventional stiffness indices were not different between groups (P > 0.05). Resting PCS and S-SR were comparable between resistance- [11.6% (10.6-12.5) and 1.46 s^-1 (1.37-1.55), respectively] and endurance-trained [11.4% (10.7-12.2) and 1.5 s^-1 (1.38-1.62)] men and superior to untrained men [9.5% (9.19-9.9); P < 0.004 and 1.24 s^-1 (1.17 - 1.31); P < 0.018)]. Both trained groups displayed comparable reductions in PCS and S-SR during IHG, which returned to resting values during recovery (P < 0.001), whereas these parameters remained unchanged in untrained men. D-SR decreased during IHG in all groups (P < 0.001), but to a lesser extent in endurance-trained men (P < 0.023), whereas β₁ and E_p increased to a similar magnitude in all groups and returned to resting values during recovery (P < 0.001).

Conclusion: Resistance- and endurance-trained men display comparable CCA 2D-Strain parameters that are superior to untrained men, which contends previous reports that resistance-training increases CCA stiffness.

Purpose: This study aimed to compare variations between the earlobe and fingertip sampling sites in exercises dominated by upper body muscle exertion. It also sought to investigate capillary blood lactate differences between Lactate Scout 4 (LS4) and a bench-top analyzer (Biosen S-Line analyzer, BSL) during Double Poling.

Methods: Blood samples were collected from the earlobe and fingertip immediately before exercise, at the end of each of five stages, and at 1-, 3-, 5-, and 7-min post-exercise. Forty healthy university students participated as volunteers. During the study, they performed double poling on a ski ergometer with progressively increasing load. Lactate levels were measured using both the BSL and LS4 analyzers.

Results: Fingertip Bla values were significantly higher than earlobe values, with a mean bias of -0.66 mmol/L, reaching -0.86 mmol/L in the 4-8 mmol/L range. At the earlobe, the highest CCC between BSL and LS4-a was 0.84 (> 8 mmol/L), and for BSL and LS4-b, it was 0.85 (> 8 mmol/L). At the fingertip, the highest CCC between BSL and LS4-c was 0.68 (> 8 mmol/L), and for BSL and LS4-d, it was 0.52 (> 8 mmol/L). Comparing LS4-a and LS4-b at the earlobe, the highest CCC was 0.83 (0-4 mmol/L). At the fingertip, comparing LS4-c and LS4-d, the highest CCC was 0.68 (> 8 mmol/L).

Conclusions: Blood lactate concentrations are higher at the fingertip than the earlobe during SkiErg double poling. The LS4 is less reliable, especially at the fingertip, so using the earlobe with the BSL analyzer is recommended for accurate measurements.

Purpose: to investigate the early consequences of type 1 diabetes (T1D) on the neural strategies of muscle force production.

Methods: motor unit (MU) activity was recorded from the vastus lateralis muscle with High-Density surface Electromyography during isometric knee extension at 20 and 40% of maximum voluntary contraction (MVC) in 8 T1D (4 males, 4 females, 30.5 ± 3.6 years) and 8 matched control (4 males, 4 females, 27.3 ± 5.9 years) participants. Muscle biopsies were also collected from vastus lateralis for fiber type analysis, including myosin heavy chain (MyHC) isoform content via protein and mRNA expression.

Results: MVC was comparable between groups as well as MU conduction velocity, action potentials' amplitude and proportions of MyHC protein isoforms. Nonetheless, MU discharge rate, relative derecruitment thresholds and mRNA expression of MyHC isoform I were lower in T1D.

Conclusions: young people with uncomplicated T1D present a different neural control of muscle force production. Furthermore, differences are detectable non-invasively in absence of any functional manifestation (i.e., force production and fiber type distribution). These novel findings suggest that T1D has early consequences on the neuromuscular system and highlights the necessity of a better characterization of neural control in this population.