European Journal of Applied Physiology最新文献

Rationale: Previous studies indicate that countermovement jump (CMJ) parameters may reflect neuromuscular fatigue following exhaustive exercise. However, changes in CMJ performance in response to non-muscle damaging exercise, and its relation to prolonged low-frequency force depression (PLFFD) is yet unknown.

Purpose: This study aimed to evaluate the relationship between PLFFD and CMJ test parameters following exhaustive cycling exercise to task failure.

Methods: A sample of 11 recreationally active adults completed an incremental cycling protocol to task failure. CMJ performance, low-frequency (10 Hz) force, and maximal voluntary contraction (MVC) force output were assessed at baseline (pre-exercise), immediately after task failure (0 min), and at 8 min, 15 min, 60 min, 24 h, and 48 h post-task failure. PLFFD was assessed as the ratio of 10 Hz to MVC force.

Results: Compared to baseline, PLFFD was larger from 0 min (7.4%) to 60-min (6.7%, p < 0.002). In contrast, no substantial changes in CMJ parameters were observed, except for a reduced concentric impulse (ConImp) lasting 8 min post-exercise.

Conclusion: The results show that CMJ parameters remain unchanged following non-eccentrically loaded exhaustive exercise, while PLFFD is significantly higher for up to 60 min post-exercise. This raises questions about the utility of CMJ as a fatigue assessment tool in athletic populations. This suggests that CMJ testing may not effectively detect the presence of PLFFD following non-muscle damaging exercise and future research should explore alternative measures for monitoring neuromuscular fatigue in training contexts.

Purpose: This study aimed to determine how exercise intensity influences the amount of work required to induce changes in cyclists' acute durability and to evaluate the suitability of using kilojoules (kJ) as a metric for fatigue monitoring.

Methods: A systematic review was conducted following PRISMA guidelines. Web of Science, Medline, and Scopus were searched for studies assessing the relationship or effect between prior accumulated work and performance reductions in cyclists. Inclusion criteria required studies to measure power output after fatigue induced within a single session, with prior work quantified in kJ or other training load metrics.

Results: Twenty-one studies were included in the systematic review. The primary finding was that high-intensity efforts (e.g., above critical power) led to greater power output reductions with lower accumulated work compared to low-to-moderate intensity efforts. Across studies, power output declines of 10-20% were observed after 2.5-15 kJ kg⁻¹ of prior high-intensity work, whereas similar or greater work volumes at lower intensities resulted in smaller performance decrements. While kJ was the most commonly used fatigue metric, it does not account for intensity, limiting its accuracy in durability assessments.

Conclusions: Exercise intensity plays a crucial role in determining durability-related performance declines. The exclusive use of kJ as a fatigue metric may be insufficient, and alternative approaches incorporating intensity are needed. These findings have implications for training prescription and race strategies, emphasizing the need for intensity-specific workload quantification.

Registration: OSF project no.: osf.io/kcg53.

Background: Controlled laboratory studies have demonstrated that breaking up sitting can reduce postprandial glucose in South Asian adults. This study examined the effects of substituting sitting with standing and walking on interstitial glucose in South Asian individuals under free-living conditions.

Methods: South Asian adults (n = 14 [50% male]; body mass index 26.5 ± 0.8 kg·m^-2) aged 41 ± 3 years completed two, 4-day regimens in a counter-balanced order: (1) SIT (restrict walking and standing to ≤ 1 h/day each) and (2) SITless (substitute ≥ 5 h/day of sitting with ≥ 3 h of standing and ≥ 2 h of walking, and interrupt sitting every 30 min). Interstitial glucose was measured using Flash glucose monitoring. Sitting and physical activity were measured with the activPAL3. Outcomes were compared between regimens using linear mixed models.

Results: Interstitial glucose net incremental area under the curve (iAUC) for waking hours was lower by - 9.2 mmol L^-1·16 h^-1 (95% Confidence Interval [CI]: - 18.1, - 0.3) in SITless than SIT (p = 0.04), while lunch postprandial glucose iAUC was significantly lower by -1.0 mmol L^-1.2 h^-1 (95% CI - 1.8, 0.2) in SITless (p = 0.02). There were no significant differences in other 24 h or 16 h glucose metrics (p ≥ 0.06). Compared to SIT, sitting was lower by - 3.6 h/day (95% CI - 4.9, - 2.3) in SITless (p < 0.01). Standing and stepping time were higher by 1.9 h/day (95% CI 0.6, 3.2) and 1.6 h/day (95% CI 1.2, 2.1) in SITless (p ≤ 0.01).

Conclusions: Substituting sitting with standing and walking under free-living conditions can be used to effectively attenuate glycaemia during waking hours, but not across 24 h, in South Asian adults.

Clinical trial registration: NCT04645875..

Exercise intolerance is a cardinal symptom in patients with heart failure (HF), and cardiopulmonary exercise testing (CPET) is the gold standard method for its assessment. The treadmill and cycle ergometers (upright and recumbent) are used in clinical practice for tracking disease progression and risk stratification, therefore, understanding the physiological differences related to ergometer is important. The aim of this study was to compare the physiological responses to exercise on treadmill and recumbent cycle ergometer in patients with HF with reduced ejection fraction (HFrEF) using a linear ramp protocol matched with controlled work rate (WR) profiles. Thirteen patients with HFrEF (left ventricular ejection fraction: 34.5% [28.7-47%]) were included. They performed two randomized ramp-incremental CPETs, on recumbent cycle and treadmill, both with incrementation rates of 10 watts per minute (W/min). The cardiorespiratory data obtained in both tests were WR-aligned and iso-WR responses were compared. Patients reached similar WR peak on both exercise modalities (84 ± 23 vs 91 ± 26 watts, P = 0.133, for recumbent cycle and treadmill, respectively) with no differences in ventilatory efficiency ( ${\dot{V}}_{\text{E}}$ / $\dot{V}$ CO₂ slope) (30.8 ± 4.7 vs 30.9 ± 7.3, P = 0.981). However, exercising on recumbent cycle resulted in lower peak oxygen uptake ( $\dot{V}$ O₂) (13.4 [11.3-15.9] vs 15.8 [14.7-18.4] mL/kg/min, p = 0.002) and higher Weber HF severity classification (p = 0.034). Considering the higher $\dot{V}$ O₂ peak reached and its role in clinical decision-making-despite similar ${\dot{V}}_{\text{E}}$ / $\dot{V}$ CO₂ slope between ergometers-treadmill should be considered the optimal ergometer for exercise intolerance and risk stratification assessment in patients with HFrEF, since it reflects a more accurate exercise capacity and disease severity.

Bicycle is an increasingly popular means of transportation, entertainment, and exercise. It is also very popular for use in recreation and various rehabilitation areas. However, there is limited research on the effects of cycling exercises on knee joint cartilage. Using two different bicycles, this study aimed to investigate the effects of exercise on healthy knee joint cartilage and lower extremity muscle thickness. This is a non-randomized prospective study. Age- and gender-matched participants were enrolled in two groups: 17 participants for recumbent bike (9 men and 8 women, aged 18-35 years) and 17 participants for upright bike (8 men and 9 women, aged 18-35 years). Using ultrasound, distal femoral cartilage thickness and regional muscle thickness of the lower limb were evaluated before and after six-week cycling exercises (20 min, 3 days/week, 60 RPM (±5) at a work rate of 60 watts). No statistically significant difference was observed between/within the groups in terms of changes in medial, intercondylar and lateral distal femoral condyle cartilage thicknesses (all p > 0.05). Posterior thigh muscle thicknesses decreased significantly in the upright bicycle group (both p < 0.05). Recumbent and upright cycling exercises seem to exert similar/no effects on knee joint cartilage and regional muscle thickness (except posterior thigh) after six weeks.

Introduction: This study aimed to compare the differential effects of unilateral, bilateral, and hybrid complex resistance training on straight punch performance in adolescent boxers and to explore the regulatory mechanisms underlying different training modalities on dominant and non-dominant-side motor performance.

Methods: This study employed a parallel group design with three intervention groups: unilateral resistance training, bilateral resistance training, and hybrid combined training. Twenty-nine right-handed orthodox stance adolescent boxers were recruited and randomly assigned to a unilateral training group (UNI, n = 10), a hybrid training group (UNI + BI, n = 9), or a bilateral training group (BI, n = 10) for an 8-week specialized resistance training intervention. Based on bilateral one-repetition maximum (1RM) test results, unilateral training loads were set at 50% of bilateral 1RM, and bilateral training loads at 85% of bilateral 1RM. The Xsens MTw Awinda inertial motion capture system and GymAware linear sensor were synchronized to measure peak punch speed and sandbag swing linear velocity for the lead hand (non-dominant side) and rear hand (dominant side).

Results: Time main effect analysis revealed that all three training modalities significantly enhanced straight punch performance for both hands (lead hand: p < 0.01; rear hand: p < 0.05). Interaction effect analysis indicated that, for lead hand straight punch performance, the unilateral group (Δ22.3%) and hybrid group (Δ20.1%) exhibited significantly greater peak speed gains than the bilateral group (Δ9.6%, p < 0.05). The main effect of training type did not reach statistical significance (p > 0.05).

Conclusion: In complex resistance training, unilateral and hybrid protocols more effectively improve non-dominant-side punching performance, likely due to neuromuscular adaptations driven by unilateral loads selectively activating weak link muscle groups and optimized motor unit recruitment through bilateral-unilateral coordinated training. It is recommended that coaches refine training designs by incorporating unilateral exercises and adjusting load distribution to enhance non-dominant-side performance and bilateral symmetry in adolescent boxers.

Purpose: Blood flow restriction (BFR) training is an exercise training modality to accelerate fatigue in exercising limbs by restricting blood flow. Although arterial inflow has been studied, its impact on venous hemodynamics remains unclear. This study examined the effects of cuff type and arm position on venous hemodynamics during BFR exercise.

Methods: Twenty-five young adults completed a randomized, crossover trial performing rhythmic handgrip exercises at 50% of maximum voluntary contraction under three conditions: no cuff (control), narrow semi-elastic (SEP) pneumatic band, and wide-rigid (WR) blood pressure cuff. Different arm positions in relation to the heart were used to account for the effect of gravity and blood pooling on the skeletal muscle pump.

Results: WR produced greater fluid retention vs SEP and No cuff. In No cuff, the increment in forearm volume was greater with the arm placed at and below the heart compared with the arm above the heart (p < 0.05). Such differences were not observed across arm positions with the BFR cuffs. Mean venous blood velocity was greater in No cuff than in SEP and WR (p < 0.001), with no differences between SEP and WR in any arm positions. In No cuff, peak venous blood velocity and venous diameter were greater when the arm was placed below the heart. No such trend was observed with the BFR cuffs. Venous diameter was greater in SEP and WR than in No cuff (p < 0.05).

Conclusion: Although venous hemodynamics are not affected by the types of cuffs, WR cuffs appear to induce greater fluid pooling.

Aim: Regular exercise is beneficial, but more exercise may not always benefit cardiovascular health (extreme exercise hypothesis). This is concerning, because ultramarathon participation is growing, but previous work on cardiovascular health among ultramarathon runners is equivocal. Prior work has not examined this population's age-related differences in prognostic cardiovascular health metrics.

Purpose: Measure brachial and central BP and arterial stiffness (carotid-to-femoral pulse wave velocity [cfPWV]) among ultramarathon runners.

Methods: We measured supine BP and cfPWV (SphygmoCor-XCEL) among 71 athletes (16 female/55 male; body mass index: 22.6 ± 1.8 kg/m²) 1-3 days before they competed in the 161-km Western States Endurance Run. We present data as mean ± SD. We analyzed the relation between age and central BP, brachial BP, and cfPWV with nonlinear (quadratic) regression.

Results: There was a significant curvilinear relation between age (46 ± 10; range 26-69 years) and central (116 ± 8 mmHg, R² = 0.18, P = 0.02) but not brachial (129 ± 9 mmHg, R² = 0.06, P = 0.11) systolic BP. There was a significant relation between age and central (79 ± 7 mmHg, R² = 0.24, P < 0.001) and brachial (78 ± 7 mmHg, R² = 0.23, P < 0.001) diastolic BP. There was a significant (R² = 0.31, P = 0.02) curvilinear relation between age and cfPWV (6.5 ± 1.0m/s). Average brachial systolic BP differed by + 1.4 mmHg/decade, and 86% of athletes had a cfPWV below age-predicted (mean difference: - 0.9 ± 1.0 m/s).

Conclusions: These are among the first data to characterize central BP and arterial stiffness across a wide age range of ultramarathon runners. Further work is needed to determine the longitudinal changes associated with training for and competing in ultramarathons.

Purposes: This study investigated the effects of two different combined exercise modalities on executive function in healthy adults and observed the associations of potential biomarkers (i.e., brain-derived neurotrophic factor, BDNF; human growth hormone, HGH; insulin-like growth factor-1, IGF-1; and cortisol) on cognitive performance.

Methods: Twelve young healthy male adults were recruited and assigned to the following three experimental interventions in a randomized crossover manner: sitting control (SC), resistance exercise plus continuous aerobic exercise (RA) and resistance exercise plus intermittent aerobic exercise (RI). Stroop Color and Word Test (SCWT) and blood collection were conducted before and immediately after each intervention.

Results: The results showed that both acute combined exercise trials significantly reduced SCWT-incongruent response time compared to the SC trial (RA: p = .015, RI: p = .014). The serum BDNF and HGH levels were significantly increased in both RA (BDNF: p < .0001, HGH: p = .004) and RI (BDNF: p = .013, HGH: p = .007) trials, and the serum IGF-1 level was significantly increased in the RI trial (p = .008). The changes in SCWT-incongruent response time were significantly associated with the changes in blood lactate (r = - 0.622, p < .0001) and RPE (r = - 0.364, p = .029) following the interventions.

Conclusion: Our findings indicate the beneficial effects of two different combined exercise modalities on executive function in these young healthy males that could be related to an increase in brain energy supply and arousal status.

Irb registration number: IRB-2021-011.

Introduction: Bovine colostrum is a nutrient-dense first milk, rich in bioactive compounds such as immunoglobulins and growth factors, which may enhance athletic performance and immune function. Rugby union involves high-intensity training for both aerobic and muscular power, which could leave athletes vulnerable to opportunistic infections.

Purpose: This double-blind, randomized study examined the effects of 8 weeks of bovine colostrum supplementation (38 g/day) versus soy protein in 29 club-level rugby players (three women) during the competitive season.

Methods: Muscular strength (1RM bench and leg press) and power (vertical jump), aerobic power (20 m shuttle run), body composition (DXA and ultrasound), and salivary immune and inflammatory markers (IgA, CRP, IL-6, IL-1β) were assessed at baseline and after 8 weeks of supplementation.

Results: Bovine colostrum supplementation significantly improved vertical jump height (+ 1.0 cm in the colostrum group; - 0.5 cm in the soy group; p = 0.0023), indicating enhanced lower body power. No significant changes were observed for upper (p = 0.38) or lower (p = 0.82) body strength, aerobic power (p = 0.16), body composition measures (p > 0.05), or salivary immune and inflammatory markers (p > 0.05) compared to the soy group. Reported incidences of illness were unaffected by bovine colostrum supplementation.

Conclusion: Bovine colostrum may enhance neuromuscular performance, specifically lower body power, but provides limited benefits for other performance metrics, body composition, or immune/inflammatory function. Future research should explore bovine colostrum's potential during off-season training or under higher immune stress conditions.