European Journal of Applied Physiology最新文献

Purpose: The rapid heart rate increase during the first seconds of exercise is primarily mediated by cardiac vagal withdrawal, which can be assessed by the 4-s exercise test (4sET), a pharmacologically validated and highly reliable procedure. However, the need for a cycle ergometer limits its applicability. Thus, we aimed to test the validity of a modified 4sET using wheelchair propulsion simulation (WPS) by comparing it with the traditional cycle ergometer protocol.

Methods: Sixty healthy adults (30 men, 30 women; 22 ± 2 years) performed, in randomized order, three repetitions each of the traditional (LEG 4sET) and modified (WPS) protocols. RR intervals were recorded via electrocardiography, and the cardiac vagal index (CVI) was calculated as the ratio of the last pre-exercise RR interval (RRB) to the shortest exercise RR interval (RRC).

Results: Mean CVI was lower for WPS compared with LEG (1.42 ± 0.03 vs. 1.48 ± 0.03; P = 0.001). Based on identity plots, a correction equation was derived for WPS values < 1.50: y = 0.7706x + 0.3861 (r² = 0.63; P < 0.001). After correction, CVI did not differ between protocols (1.48 ± 0.17 vs. 1.48 ± 0.20; P = 0.854). Furthermore, a high and significant intraclass correlation coefficient (ICC) was found for the CVI between the protocols (ICC = 0.87; [0.74-0.93]; P < 0.05), and Bland-Altman analysis showed negligible bias and acceptable limits of agreement for the corrected WPS CVI.

Conclusion: The WPS shows strong agreement with the traditional cycle ergometer 4sET, supporting its validity as a simpler and more accessible method for assessing dynamic cardiac vagal control.

Purpose: Static spirometry parameters may offer practical alternatives to estimate maximum oxygen consumption (V̇O_2max) in athletic populations. This study evaluated forced vital capacity (FVC) as a predictor of V̇O_2max across different sports, developing prediction equations for field-based assessment.

Methods: Four hundred twenty-two athletes (324 males, 98 females; age 22.9 ± 8.5 years) from cycling (n = 123), swimming (n = 68), triathlon (n = 60), multisport (n = 83), and other sports (n = 88) performed spirometry and maximal incremental testing. V̇O_2max was directly measured using breath-by-breath gas analysis. LASSO regression identified predictors, with Bland-Altman analysis assessing agreement.

Results: FVC and gender emerged as significant predictors (R² = 0.690, P < 0.001). The equation V̇O_2max (L·min^-1) = (FVC × 0.61) + (Gender × 0.86) yielded SEE = 0.65 L·min^-1. Including additional variables (Maximum voluntary ventilation, body weight, age) marginally improved prediction (R² = 0.712) but reduced practical utility. Coefficient of variation between measured and predicted values was 12.1%. Sport-specific analysis revealed highest predictive accuracy in swimmers (R² = 0.893).

Conclusion: FVC provides reasonable population-level V̇O_2max estimates in athletes, though individual predictions require caution given substantial unexplained variance (31%). Sport-specific equations, particularly for swimming populations, enhance predictive accuracy. These findings offer practical screening tools for coaches lacking access to metabolic testing equipment, though direct measurement remains the gold standard for individual assessment.

Objectives: Because the ankle-foot complex is a frequent target of cryotherapy in sports medicine, establishing location-specific duration guidance has practical clinical relevance. Thus, the aim of this study was to determine how ankle-applied cold compression duration shapes microvascular perfusion at the foot dorsum, cold-induced vasodilation (CIVD), post-cooling hyperaemia, and analgesia, and to identify a pragmatic exposure window that maximizes vasoconstriction and pressure-pain threshold (PPT) while limiting CIVD/hyperaemia in healthy adults.

Methods: Prospective, randomized, controlled, parallel-group trial with a repeated-measures duration factor using an ankle-foot cuff. Sixty healthy volunteers were allocated 1:1 to Active cold compression (ACC; ~3 °C, 5-75 mmHg) or sham (shamCC; 20 °C, ~ 15 mmHg). Each participant completed four sessions (5, 10, 15, 20 min), order randomized with ≥ 7-day washouts. Primary outcomes were laser-Doppler perfusion indices at the foot dorsum; secondary outcome was PPT by algometry.

Results: Minimum perfusion (nadir) showed a strong duration effect and a condition×group interaction; ACC achieved lower perfusion than sham at 5, 10, 15, and 20 min (all p < 0.001), with progressive nadir reductions from 10→20 min in ACC (p ≤ 0.018). Time-to-nadir decreased with longer exposures (main effect p < 0.001). CIVD at the foot increased with duration and was higher in ACC at 15 min (p = 0.004) and 20 min (p < 0.001). Post-cooling hyperaemia (AUC) showed large effects for duration and group; between-group differences favored ACC at 0-15 min for all durations (all p ≤ 0.001), with stepwise increases from 5→20 min in ACC (all p < 0.001). Post-peak perfusion was greater with ACC at 10-20 min (all p < 0.001). At post-intervention PPT was higher with ACC at 5 min (p = 0.005), 10 min (p < 0.001), 15 min (p < 0.001), and 20 min (p < 0.001). Within ACC, 10, 15, and 20 min produced similar (and greater) PPT improvements, each exceeding 5 min (all p ≤ 0.001).

Conclusion: ACC elicited dose-dependent vasoconstriction and robust hypoalgesia, with PPT improvements plateauing by 10 min. Because CIVD and post-cooling hyperaemia escalated at ≥ 15 min, a 10-minute ACC bout best balanced analgesia with vascular control, limiting disproportionate rebound perfusion and preserving a physiological equilibrium between vasoconstriction and vascular reopening; extending to 15 min can be reserved for cases needing marginal additional relief.

Trial registration: ISRCTN90040217; date: 25/05/2023.