European Journal of Applied Physiology最新文献

Athletes generally suffer from insufficient sleep duration, lower sleep efficiency, and a high overall prevalence of insomnia. Daytime napping has been demonstrated to supplement nighttime sleep in athletes; however, recent controversial findings warrant further consideration. This review synthesized existing studies on the effects of daytime naps on athletes, explored potential mechanisms of daytime napping, and analyzed instances of ineffective interventions or negative outcomes. Daytime napping functions as a restorative strategy to counteract sleep deprivation or the post-lunch dip, assisting athletes in recovering anaerobic capacity, agility, reaction time, and alertness, with potential mechanisms including the reduction of sleepiness through adherence to circadian rhythms, decreased subjective soreness and fatigue attributed to autonomic functioning, and improved respiratory performance. The optimal nap period occurs between 13:00 and 15:00, with a 5-6 h interval between morning awakening and nap initiation. Depending on the athlete's nighttime sleep, opt for a 20 ~ 40 or 60 ~ 90 min nap with at least 60 min between the nap and subsequent exercise to reduce sleep inertia. The intervention efficacy of daytime napping was correlated with exercise intensity. A nap program must be developed based on the specific athletic demands of the sport in practical application.

Purpose: Exercise-induced fatigue can reduce motor control performance and increase the risk of sporting injuries, which are related to functional coupling within the corticomotoneuronal pathway. However, the differences in functional coupling caused by general and local muscular exercise-induced fatigue are unknown. This study aimed to investigate the effects of exercise-induced fatigue on the beta-band (16-30 Hz) functional coupling between the sensorimotor cortex (SM1) and muscles of the dominant lower limb under different fatigue protocols.

Methods: Twenty-four healthy male participants were recruited to participate in randomized sessions of personalized constant speed running as general muscular exercise (GME) and maximum isokinetic ankle plantar-dorsiflexion as local muscular exercise (LME) to induce fatigue. These sessions were separated by 7 days. The electroencephalogram (EEG) signals of SM1 (e.g., FC1, FCz, and Cz) and surface electromyography signals (sEMG) of four muscles (soleus, SOL; medial gastrocnemius, MG; later gastrocnemius, and LG; tibialis anterior, TA) were simultaneously recorded before and after fatigue during the ankle plantar-dorsiflexion task, which were used for beta-band coherence analyses.

Results: Following fatigue induced by GME, the EEG-sEMG coherence was significantly greater than that induced by LME (P < 0.04). Compared to pre-fatigue state, the coherence of FC1-SOL, FCz-SOL, and Cz-SOL increased significantly after general fatigue, while these coherences decreased significantly after local fatigue.

Conclusion: Fatigue induced by GME indicates an enhancement in beta-band functional coupling between the SM1 and muscles of the dominant lower limb, which is related to higher motor control performance. In contrast, fatigue induced by LME diminishes the functional coupling.

Purpose: (1) To determine if the blood lactate concentration ([BLa]) response is a repeatable individual trait, and (2) To examine whether threshold-based prescription (THR) reduces interindividual variability in [BLa] response compared to traditional (maximally anchored) exercise prescription (TRAD).

Method: A crossover within-participant repeated measures design was used to assess [BLa] during the TRAD and THR exercise in 17 participants (9 M/8F). Participants initially undertook an incremental test to exhaustion to determine peak work rate (WRpeak), a lactate threshold (LT) test and a critical power (CP) test. All baseline tests were repeated twice. Participants then completed 6 15-min bouts of continuous cycling at 65%WRpeak (TRAD; 3 bouts) and 80% of the difference (Δ80) between LT and CP (THR; 3 bouts). [BLa] response was measured at 10 and 15 min of exercise.

Results: Across individuals, there was a wide range in [BLa] response, but within individual responses were repeatable. [BLa] ranges and mean individual 90% confidence interval width (CI_w) were as follows: TRAD@10 min = 2.1-9.7 mmol, CI_w = 0.5 mmol, THR@10 min = 3.4-9.3 mmol, CI_w = 0.6 mmol, TRAD@15 min = 2.2-9.9 mmol, CI_w = 0.6 mmol, THR@15 min = 3.6-12.3 mmol, CI_w = 0.7 mmol. Levene's tests revealed no significant differences in the variability of [BLa] response between TRAD and THR at 10 min (F = 0.523, p = 0.475) or 15 min (F = 0.351, p = 0.558) of exercise.

Conclusion: Our results demonstrate that true interindividual variability in the [BLa] response to exercise exists, but failed to confirm that variability in [BLa] response is reduced with the use of THR.

Purpose: Field-based measures of durability (exercise-related physiologic deterioration over time) for assessing athletic fitness often rely on changes in maximal power profiles or heart rate (HR) drift. This study aimed to determine whether an index of HR variability based on the short-term exponent of Detrended Fluctuation Analysis (DFA a1) along with respiratory frequency (fB) could demonstrate changes in durability during a Time to Task Failure (TTF) Trial.

Methods: Ten participants performed a cycling TTF at an intensity of 95% of the respiratory compensation point (RCP) on two occasions, Control and a "Reward" where a monetary incentive was offered when task failure was signaled. Metabolic responses including oxygen uptake ( ${\dot{\text{V}}\text{O}}_2$ ), lactate and glucose along with HR, DFA a1 and fB were measured and compared over each quarter of the TTF up to the time of signaling (Q1, Q2, Q3, and Q4).

Results: The elapsed time of TTF sessions was statistically similar (p = 0.54). After initial equilibration, metabolic responses remained largely stable over Q2-Q4. HR, DFA a1 and fB displayed drift over Q2-Q4 with significant ANOVA. Repeatability of quarterly HR, DFA a1, and fB between Control and Reward sessions was high with ICC between 0.73 and 0.94, Pearson's r was between 0.83 and 0.98 with no difference in mean values by paired t testing.

Conclusion: HR, fB and DFA a1 are useful metrics representing alteration in physiologic characteristics demonstrating durability loss during an endurance exercise session. These measures were repeatable across sessions and have the potential to be monitored retrospectively or in real time in the field with low-cost consumer equipment.

Background and aims: Besides muscle damage, eccentric contractions also impose significant mechanical loads on peripheral nerves. However, the impact of eccentric contractions on peripheral nerve properties remains unclear. We aimed to reveal the immediate (i.e., <2 h and short-term (i.e., <10 days) effects of eccentric contractions on functional, structural, morphological, physiological and biomechanical properties of peripheral nerves.

Methods: Four electronic databases (PubMed, Science Direct, PEDro and Cochrane) were searched for animal and human studies which evaluated the immediate and/or short-term impact of eccentric contractions of upper or lower limb muscles on outcomes related functional, structural, morphological, physiological and biomechanical properties of peripheral nerves.

Results: From a total of 2415 articles, two human and two animal studies met the selection criteria. Several signs of nerve damage following eccentric exercises were observed, such as reductions in myelin sheath thickness, nerve fibre diameter, sensory and motor nerve conduction velocity, and protein zero levels, alongside increased levels of macrophage-related protein and tropomyosin receptor kinase C. No significant changes were identified in growth-associated protein 43. It is worth noting that some variables exhibited differences in their time course between human and animal studies. Animal studies revealed that the effects were more pronounced when eccentric contractions were performed at higher velocities.

Conclusion: Current evidence is suggestive that eccentric contractions has the potential to alter the peripheral nerves structural, morphological, functional and physiological properties, which are indicative of nerve damage.

Systematic review registration: CRD42021285767.

Purpose: The purpose of the study was to explore the validity, test-retest reliability and affective responses of a submaximal 20-m shuttle-run test (20mSRT) stopped at 6 on the Eston-Parfitt (EP) scale. The secondary aim was to examine and compare two submaximal 20mSRT protocols with different RPE end points (EP6 vs. EP7) using previously published data.

Methods: Twenty-five children (16 boys; 13.4 ± 1.0 years; 162.1 ± 8.7 cm; 49.1 ± 6.6 kg) completed three exercise tests (graded exercise test [GXT], 2 submaximal 20mSRT). The EP scale and Feeling scale were used to measure RPE and affect, respectively. The two submaximal 20mSRTs were stopped after participants reported EP6. Individual speed-RPE relationships from the submaximal 20mSRTs were linearly regressed to predict peak speed and then used to estimate VO_2peak. Previously published data (n = 25) used comparable methods, except that the participants stopped at EP7.

Results: In the EP6 protocol, a two-factor repeated measures ANOVA revealed non-significant Test and Sex main effects (p > 0.05). Reliability analysis revealed intraclass correlation coefficient of ~ 0.7 (95%CI [0.432,0.867], p < 0.001) between the submaximal 20mSRTs. Significant differences in end-test affect between the GXT and submaximal 20mSRTs were found (p < 0.001), with GXT more negative. ANOVA revealed no significant differences in end-test affect between EP6 and EP7 protocols; however, frequency count analysis revealed EP6 to result in more positive end-test affect.

Conclusion: Submaximal 20mSRT utilising RPE may offer valid predictions in VO_2peak while minimising negative affect. Test end points of EP6 and EP7 both offer valid predictions in VO_2peak. EP6 may be more beneficial in avoiding negative affect, even though a reduction in test-retest reliability was observed.

Purpose: Oxygen extraction in skeletal muscle is an important determinant of exercise tolerance. Prolonged sitting decreases oxygen extraction in the gastrocnemius muscle. However, the underlying mechanism remains unknown, and preventive measures are yet to be established. Therefore, we aimed to elucidate the mechanism by which prolonged sitting decreased muscle oxygen extraction and investigate preventive measures.

Methods: Ten healthy young males (age 21.2 ± 0.4 years; body mass index, 20.5 ± 1.3 kg/m²) were randomly assigned to each of the following conditions: 3-h supine (CON), 3-h sitting (SIT), and 3-h fidgeting of one lower leg during sitting (FID). Oxygen extraction from the gastrocnemius muscle was measured using near-infrared spectroscopy and the vascular occlusion test under each condition. The rate of change in total Hb + Mb (THb) was measured as an indicator of venous stasis and interstitial fluid accumulation in the lower leg.

Results: Muscle oxygen extraction was significantly lower at 180 min for SIT and FID than for CON (4384.2 ± 1426.8; 5281.5 ± 1823.7; 6517.4 ± 1390.8 a.u., respectively) and significantly higher for FID than for SIT (5281.5 ± 1823.7 vs. 4384.2 ± 1426.8 a.u., respectively). The rate of THb change was significantly higher at 180 min for SIT than for CON and FID (12.9 ± 15.1; -2.3 ± 5.7; 2.2 ± 11.6%, respectively). However, no significant difference was observed between CON and FID.

Conclusion: We found that 3-h prolonged sitting reduced oxygen extraction in the gastrocnemius muscles due to reduced oxygen supply to capillaries and increased distance between capillaries and myocytes. However, leg fidgeting alleviated this effect in healthy young males.

Trial registration number: UMIN000050531 (March 8, 2023).

Purpose: Vigorous physical activity may acutely trigger the onset of an acute coronary syndrome especially in sedentary persons with established cardiovascular risk factors such as arterial hypertension. The rupture of an inflamed coronary plaque and the activation of the coagulation cascade are the main underlying mechanisms. The present study aimed to determine the effect of acute exercise on the inflammatory and thrombotic response in patients with arterial hypertension as compared to normotensive peers.

Methods: After excluding patients with any inflammatory or/and coronary artery disease, a total of 60 non-treated hypertensive patients and 65 normotensive individuals underwent a maximal treadmill exercise testing. Βlood samples were drawn at rest and immediately after peak exercise. High-sensitivity C-reactive protein (hsCRP), serum amyloid A (SAA), white blood cell (WBC), interleukin-6 (IL-6), and total fibrinogen (TF) levels, as well as plasminogen activator inhibitor-1 (PAI-1) activity, were measured.

Results: All biomarkers increased with exercise, except PAI-1, which decreased (P < 0.05 for the change between resting and peak exercise for all biomarkers). Αfter adjusting for relevant confounders (duration of exercise, metabolic equivalents, systolic BP, and rate-pressure product achieved at peak exercise), the normotensive group had less marked (P < 0.05) exercise-induced changes than the hypertensive group in hsCRP (7.7 vs. 8.6%), SAA (5.6 vs. 11.9%), WBC (45.0 vs. 51.7%), and PAI-1 (-17.3 vs. -20.1%) and a similar (P = NS) change in IL-6 (23.8 vs. 23.0%) and TF (8.5 vs. 8.5%).

Conclusion: In conclusion, the acute exercise-induced inflammatory and thrombotic response seems to be more pronounced in non-treated hypertensive patients than in normotensive controls. Possible clinical implications of this finding merit further examination.