European Journal of Applied Physiology最新文献

Purpose: This study aimed to investigate whether the variable dose-response model, with estimates free to vary over time, can account for overreaching during intensified training in swimmers.

Methods: A time-varying model using a recursive least squares algorithm was applied to data from eight swimmers collected over 61 weeks, comprising five training cycles. Each data set included daily training load calculated from pool kilometers and dry land training equivalents, and performance measured twice weekly from 50 m trials. Weekly changes in model parameters were used to calculate the model impulse response that is defined as the time course of performance after a single training session.

Results: Functional overreaching was evidenced by a significant decline in performance within four cycles of increased training, followed by a peak in performance after two or three weeks of reduced training. Model estimates from the time-varying model provided markers to distinguish overreaching from acute fatigue during intensified training. When an increase in training led to a decrease in performance, the characteristics of the modelled impulse responses showed a significant increase in the acute negative effect and a decrease in the delayed positive effect of a single workout.

Conclusions: Weekly variations in estimates from a time-varying model could be useful in diagnosing overreaching from changes in the acute negative effect and delayed positive effect of training. This information provided by the model at a particular point in the training process could help practitioners to re-adjust subsequent training.

Purpose: Alpine skiing races are physically demanding events characterized by numerous repeated near-maximal activations of the lower limb muscles. Although this type of task is known to induce neuromuscular fatigue, electromyographic activity (EMG) adaptations after repeated maximal-intensity skiing have not been previously investigated.

Methods: Six skiers completed a 6-turns section with (FAT) and without performing 30 giant slalom (GS) turns (CONT). Isometric knee extensors maximal force (F_max) was measured before and immediately after both conditions. On-snow EMG activity of VM, VL, RF, BF, SMST and GM muscles were compared between conditions for both the outside (OL) and inside (IL) legs using turn-averaged EMG amplitude (RMS_OL and RMS_IL) and EMG mean power frequency (MPF_OL and MPF_IL). EMG time-frequency maps were also computed and compared between conditions using statistical parametric mapping (SPM) analysis.

Results: F_max was significantly lower after FAT (-20.1%, p < 0.001), but did not change after CONT. RMS_OL was lower in FAT for BF (-26.8%, p = 0.020). RMS_IL was lower in FAT for VM (-24.7%, p = 0.036) and GM (-27.3%, p = 0.021). MPF_OL was lower in FAT for VM (-8.2%, p = 0.028), VL (-11.3%, p = 0.025), RF (-13.1%, p = 0.007), SMST (-9.3%, p = 0.004) and GM (-7.4%, p = 0.034). MPF_IL was lower in FAT for VM (-13.0%, p = 0.016) and RF (-11.1%, p = 0.034). SPM analysis indicated that the initiation phase of the turn was specifically affected.

Conclusion: Thirty GS turns led to a substantial decrease in F_max and altered motor command, as indicated by reduced EMG frequency content, specifically in the initiation phase of the turn. The present pilot data highlight the importance of characterizing neuromuscular fatigue in competitive GS skiing.

Purpose: 7 days L-citrulline supplementation has been reported to improve blood pressure, $\stackrel{.}{\text{V}}$ O₂ kinetics, gastrointestinal (GI) perfusion and endurance cycling performance through increasing arterial blood flow. In situations where blood volume is compromised (e.g., hyperthermia/hypohydration), L-citrulline may improve thermoregulation and exercise performance by redistributing blood flow to aid heat loss and/or muscle function. This study assessed 7 days L-citrulline supplementation on running performance in the heat, whilst mildly hypohydrated.

Methods: 13 endurance runners (2 female, 31 ± 8 y, $\stackrel{.}{\text{V}}$ O₂peak 60 ± 6 mL/kg/min) participated in a randomised crossover study with 7 days L-citrulline (CIT; 6 g/d) or placebo (maltodextrin powder; PLA) supplementation. Participants completed a 50 min running 'preload' at 65% $\stackrel{.}{\text{V}}$ O₂peak (32 °C, 50% relative humidity) to induce hyperthermia and hypohydration before a 3 km running time trial (TT). Body mass and blood samples were collected at baseline, pre-preload, post-preload and post-TT, whilst core and skin temperature, heart rate and perceptual responses were collected periodically throughout.

Results: TT performance was not different between trials (CIT 865 ± 142 s; PLA 892 ± 154 s; P = 0.437). Core and skin temperature and heart rate (P ≥ 0.270), hydration (sweat rate, plasma volume, osmolality) indices (P ≥ 0.216), GI damage (P ≥ 0.260) and perceptual responses (P ≥ 0.610) were not different between trials during the preload and TT.

Conclusions: 7 days of L-citrulline supplementation had no effect on 3 km running performance in the heat or any effects on thermoregulation or GI damage in trained runners in a hypohydrated state.

Background: A systematic evaluation and network meta-analysis (NMA) using randomized controlled trials (RCTs) was conducted to investigate the effects of different exercise intensities and dosages on the mental health of college students.

Methods: A systematic search of eight electronic databases of RCTs involving mental health exercise interventions for college students was conducted, which included data from the inception of the databases through July 2024. Two independent reviewers assessed the quality of the literature. Pairwise, network, and dose‒response meta-analyses were conducted via random-effects models to analyze the effects of exercise on college students' mental health.

Results: A total of 48 RCTs (3951 patients) were included. Light, moderate, and vigorous exercise were all significantly effective at reducing symptoms of depression, anxiety and stress, whereas very light exercise was only effective at reducing symptoms of depression and stress. Surface under the cumulative ranking curve (SUCRA) probability ranking revealed that vigorous exercise had the highest probability of being the best intervention intensity to improve depression and stress symptoms, and the best exercise intensity to improve anxiety symptoms was moderate. The minimum threshold for overall exercise intervention for depressive symptoms was 150 METs-min per week, the benefits provided after doses above 1300 METs-min per week were less pronounced, and the predicted maximum significant response dose was 860 METs-min per week, which was the same as the predicted data for moderate exercise.

Conclusion: Very light, light, moderate, and vigorous exercise are all potentially effective exercise intensities for improving the mental health of college students, with no significant difference in effectiveness across the four exercise intensities. SUCRA rankings revealed that vigorous exercise is the most effective intervention for depression and stress and that moderate exercise is the most effective intervention for anxiety. Exercise interventions for depressive symptoms have a low dosage threshold, are simple and easy to administer, and are good treatments for psychological problems in college students.

Cold-induced vasodilation (CIVD) is a physiological response characterized by cyclic vasodilation occurring within 5-10 min of cold exposure, predominantly in the fingers and toes. This study aimed to determine the roles of body dimensions, specifically surface-to-mass (SM) ratio and sex in modulating CIVD responses. Thirty-nine participants (mean ± SD age: 24 ± 3 yr; height: 174 ± 28 cm; weight: 75.3 ± 15.2 kg; 20 males & 19 females) completed a 30-min immersion of the digits in ice water while sitting in a thermoneutral room (22 °C). Skin temperature was measured continuously on the anterior pads of the index, middle, ring, and little finger to assess CIVD parameters (onset time (t_onset), minimum finger temperature (T_min), maximum finger temperature (T_max), mean finger temperature (T_mean), and CIVD_waves). A negative relationship was observed between T_max and SM ratio (r =  - 0.39, p = 0.001) and T_mean and SM ratio (r =  - 0.32, p = 0.001), indicating that individuals with smaller SM ratios exhibited enhanced CIVD responses. A subgroup of 7 males and 7 females with identical anthropometrics from the original cohort showed no differences between any CIVD parameter: T_mean (Males: 8.0 ± 1.9 °C; Females: 8.9 ± 1.6 °C, p = 0.36), T_max (Males: 11.2 ± 3.1 °C; Females: 13.1 ± 1.2 °C, p = 0.16), T_min (Males: 5.9 ± 1.4 °C; Females: 5.0 ± 1.7 °C, p = 0.31), and t_onset (Males: 12.0 ± 4.4 min; Females: 9.6 ± 3.6 min, p = 0.28). Therefore, body dimensions seem to play a crucial role in modulating CIVD responses, whereas sex does not.

Purpose: Maximal oxygen consumption (VO₂max), the predominant index of cardiorespiratory fitness (CRF), is a predictor of whole-body function and longevity in humans. The central cardiac function and the skeletal muscle's capacity to use oxygen are key determinants of VO₂max. Murine Double Minute 2 (MDM2), mainly known as an oncogene, could regulate myocardial hypertrophy, skeletal muscle angiogenesis, and oxidative phosphorylation. A prevalent single nucleotide polymorphism in the MDM2 promoter (SNP309) substitutes a T for a G, supporting a greater transcriptional activity. We aim to assess whether SNP309 impacts intrinsic CRF.

Methods: 82 young healthy nonathletic male and female adults aged 23 ± 2 years performed cardiorespiratory exercise testing to determine their VO₂max (mL kg^-1 min^-1). The genomic DNAs isolated from saliva were genotyped using Taqman-based qPCR.

Results: A one-way ANOVA showed that SNP309 influenced relative VO₂max in the whole cohort (p = 0.044) and in men (p = 0.009), remaining non-significant in women (p = 0.133). VO₂max was higher in TT homozygotes than in GT heterozygotes (whole cohort, 47 ± 12 vs. 42 ± 6 mL kg^-1 min^-1, p = 0.030; men, 53 ± 8 vs. 45 ± 6 mL kg^-1 min^-1, p = 0.011). A contingency analysis revealed a positive association between SNP309 in men in which the TT genotype was more frequent in the high VO₂max group (p = 0.006). When considering G as the dominant allele, men bearing a G allele had lower relative VO₂max than TT homozygotes (47 ± 7 vs. 53 ± 8, GG/GT vs. TT, p = 0.010). Conversely, women bearing a G allele had a higher relative VO₂max than TT homozygotes (39 ± 5 vs. 34 ± 7, GG/GT vs. TT, p = 0.047).

Conclusion: SNP309 impacts VO₂max in a sex-dependent manner in our cohort.

Introduction: Evidence that caffeine supplementation is effective to improve performance in cycling time trials has been obtained in single rather than multiple time trials. We investigated whether 5 mg.kg^-1 of caffeine enhanced performance in multiple 4 km cycling time trials (TT4km) conducted within the same day and across different days.

Methods: After selection of eligible cyclists and familiarization with the TT4km, thirteen well-trained cyclists participated in a balanced placebo-controlled designed with two caffeine sessions (CAF-1 and CAF-2) and a placebo session. In each session, cyclists performed a baseline TT4km before caffeine, and two supplemented TT4km (50 min and 80 min after supplementation). Relative and absolute reliability were obtained through intraclass coefficient correlation and standard error of the measurement (SEM), respectively. The cyclists' performance responses to caffeine were classified as beneficial, unchanged, and adverse by calculating the change between caffeine and placebo relative to SEM.

Results: Caffeine enhanced performance in the first supplemented TT4km in CAF-1 and CAF-2 (0.5% and 1.8%, respectively), although only CAF-2 was significantly different from placebo (p < 0.001). Analysis with grouped data showed good absolute and relative reliability of caffeine effects within and across days. However, analysis of individual data showed that 38% and 31% of the cyclists changed their classification of responsiveness to caffeine between the supplemented trials across days.

Conclusions: Despite the good reliability of caffeine to enhance performance in a single TT4km performed within and across days, individual analysis challenged the use of caffeine supplementation protocols based on grouped data.

Carbohydrate (CHO) intake during exercise could decrease the subjective perceived exertion and promote recovery; however, the effects of intra-training CHO ingestion remain uncertain in CrossFit® (CF) sessions. Therefore, the aim of this randomized, triple-blind, placebo-controlled crossover trial was to investigate the effect of acute CHO intake during a CF session on the delayed onset muscle soreness (DOMS), the perceived exertion (RPE), performance, recovery, and metabolic markers (capillary lactate and glucose) in CF athletes. Twenty-three male athletes trained in CF ingested CHO (60 g of maltodextrin + fructose) or a placebo (PLA) during a CF session. DOMS was assessed 24 and 48 h after the CF session. The Counter Movement Jump (CMJ) test and the Deep Squat test at 70% of the athlete's body weight (AST70) were performed before, immediately after, and 24 h after the session. Perceived exertion, Feeling Scale (FS), Gastrointestinal Distress Score (GDS), heart rate, capillary lactate, and glucose were assessed across the session. CHO supplementation did not improve DOMS (all P ≥ 0.127), CMJ, or AST70 parameters (all P ≥ 0.053) compared to PLA. There were no differences between CHO and PLA in RPE, FS, GDS, heart rate (all P ≥ 0.088), performance (e.g., nº of repetitions; all P ≥ 0.556), or lactate levels (P = 0.810). However, glucose levels increased from the back squat to the WOD and remained stable after the AMRAP (P < 0.001). In conclusion, acute CHO intake during a CF session did not improve DOMS, perceived exertion, performance, recovery, or metabolic markers in CF athletes. TRN: NCT06440343. Date: 2024-05-10.

Purpose: This study aimed to investigate whether lumbar delayed-onset muscle soreness (DOMS) impacts the magnitude of the flexion relaxation phenomenon regionally.

Methods: Eighteen adult participants (9 men and 9 women) performed flexion extension movement under two conditions (with and without DOMS). Lumbar muscle activation strategies were recorded using high-density surface electromyography (HDsEMG) on both sides of the trunk. To determine the spatial distribution of flexion relaxation phenomenon, flexion relaxation ratio of muscle activity was computed for all electrodes of the HDsEMG grid and the coordinates of the centroid (average position of flexion relaxation ratio across the HDsEMG grid) in the mediolateral and craniocaudal axis were calculated.

Results: The results revealed a cranial shift (~ 6 mm) of flexion relaxation phenomenon within the lumbar extensor muscles when DOMS was present (both sides: p < 0.05), possibly attributed to the increased recruitment of lumbar stabilizing muscles located caudally, which may serve as a guarding mechanism to pain.

Conclusion: These results highlight the importance of evaluating the entire lumbar region when assessing the flexion relaxation phenomenon.

Purpose: The risk of exercise-induced rhabdomyolysis, followed by abrupt creatine kinase (CK) augmentation, associated with carnitine palmitoyl transferase II (CPTII) deficiency causes patients to abstain from physical training. However, the exercise adjustment to the disease-induced metabolic impairment, accompanied by a tailored nutritional and supplementation strategy, could make sporting activity feasible, even at a competitive level. Here, we report the case of an 18-year-old male basketball player at a competitive level diagnosed for CPTII deficiency after a rhabdomyolytic event. Subsequent genetic analysis revealed the previously unreported c.1741C > T genetic mutation.

Methods: The patient underwent a battery of tests to evaluate nutrition (indirect calorimetry; 8-day food records), hydration (bioimpedance analysis), and the use of energy substrates during exercise (cardiopulmonary exercise test, CPET).

Result: Inadequate macronutrients distribution with respect to the reference values for CPTII deficiency, an optimal hydration status, and a non-physiological prevalence of carbohydrates consumption all along the CPET, accentuated with workload augmentation, were found. Based on the results, the patient was provided with a personalized nutritional (carbohydrate = 50-55%, fat = 20%, and protein = 25-30% of total energy) and supplementation (medium-chain triglycerides, β-alanine, and creatine citrate) plan, and indications on the exercise intensity to be adopted to avoid the contribution of fat to energy production. Monitoring of CK for the five months following the resumption of sporting activity shows that the patient no longer had rhabdomyolysis.

Conclusion: These findings suggest that tailoring exercise, nutrition and supplementation upon the disease-induced metabolic limitation makes sport activity at a competitive level feasible in a CPTII-deficient patient, prompting further analysis on larger cohorts.