The constant work rate critical power protocol overestimates ramp incremental exercise performance

Purpose: The parameters of the power-duration relationship (i.e., the critical power, CP, and the curvature constant, W′) may theoretically predict maximal performance capability for exercise above the CP. The CP and Wʹ are associated with the parameters of oxygen uptake (V ˙ O2) kinetics, which can be altered by manipulation of the work-rate forcing function. We tested the hypothesis that the CP and Wʹ derived from constant work-rate (CWR) prediction trials would overestimate ramp incremental exercise performance. Methods: Thirty subjects (males, n = 28; females, n = 2) performed a ramp incremental test, and 3–5 CWR prediction trials for the determination of the CP and Wʹ. Multiple ramp incremental tests and corresponding CP and Wʹ estimates were available for some subjects such that in total 51 ramp test performances were predicted. Results: The ramp incremental test performance (729 ± 113 s) was overestimated by the CP and Wʹ estimates derived from the best (751 ± 114 s, P < 0.05) and worst (749 ± 111 s, P < 0.05) individual fits of CWR prediction trial data. The error in the prediction was inversely correlated with the magnitude of the Wʹ for the best (r = −0.56, P < 0.05) and worst individual fits (r = −0.36, P < 0.05). Conclusions: The overestimation of ramp incremental performance suggests that the CP and Wʹ derived from different work-rate forcing functions, thus resulting in different V ˙ O2 kinetics, cannot be used interchangeably. The present findings highlight a potential source of error in performance prediction that is of importance to both researchers and applied practitioners

Effects of montmorency tart cherry (L. Prunus Cerasus) consumption on nitric oxide biomarkers and exercise performance

The purpose of this study was to investigate the effects of Montmorency tart cherry juice (MC) on nitric oxide (NO) biomarkers, vascular function and exercise performance. In a randomized, double blind, placebo (PLA) – controlled, crossover study, 10 trained cyclists (mean ± SD; V̇O2peak 59.0 ± 7.0 ml/kg/min) acutely ingested 30 mL of either MC or PLA following dietary restrictions of polyphenol‐rich compounds, and completed 6 min moderate‐ and severe‐intensity cycling bouts 1.5 h post ingestion on two occasions for each experimental condition. The severe‐intensity cycling test was continued to exhaustion on one occasion and immediately followed by a 60 s all‐out sprint on the other occasion. Blood pressure, pulse wave measures, tissue oxygenation index and plasma nitrite concentration were assessed pre and 1.5 h post ingestion. Time to exhaustion was not different between conditions (P > 0.05), but peak power over the first 20 s (363 ± 42 vs. 330 ± 26 W) and total work completed during the 60 s all‐out sprint (21 ± 3 vs. 19 ± 3 kJ) were 10% higher in the MC trial compared to the PLA trial (P 0.05). These results suggest that acute supplementation with MC can lower blood pressure and improve some aspects of exercise performance, specifically end‐sprint performance, in trained cyclists

Road cycle TT performance: Relationship to the power-duration model and association with FTP

Purpose: To determine the accuracy of critical power (CP) and Wʹ (the curvature constant of the power-duration relationship) derived from self-paced time-trial (TT) prediction trials using mobile power meters to predict 16.1 km road cycling TT performance. This study also aimed to test the agreement between functional threshold power (FTP) and CP. Methods: Twelve competitive male cyclists completed an incremental test to exhaustion, a 16.1-km road TT, an FTP test, and 4–5 self-paced TT bouts on a stationary bike within the lab, using mobile power meters. Results: CP and Wʹ derived from the power-duration relationship closely predicted TT performance. The 16.1 km road TT completion time (26.7 ± 2.2 min) was significantly correlated with the predicted time-to-completion (27.5 ± 3.3 min, r= 0.89, P0.05); however, the limits of agreement between CP and FTP were 30 to -36 W. Discussion: The findings of this study indicate that CP and Wʹ determined using mobile power meters during maximal, self-paced TT prediction trials can be used to accurately predict 16.1-km cycling performance, supporting the application of the CP and Wʹ for performance prediction. However, whilst we demonstrated that the FTP was not significantly different from CP, the limits of agreement were too large to consider FTP and CP interchangeable

Acute acetaminophen ingestion improves performance and muscle activation during maximal intermittent knee extensor exercise

Aim: Acetaminophen is a commonly used medicine for pain relief and emerging evidence suggests that it may improve endurance exercise performance. This study investigated some of the physiological mechanisms by which acute acetaminophen ingestion might blunt muscle fatigue development. Methods: Thirteen active males completed 60 × 3 s maximum voluntary contractions (MVC) of the knee extensors with each contraction separated by a 2 s passive recovery period. This protocol was completed 60 min after ingesting 1 g of maltodextrin (placebo) or 1 g of acetaminophen on two separate visits. Peripheral nerve stimulation was administered every 6th contraction for assessment of neuromuscular fatigue development, with the critical torque (CT), which reflects the maximal sustainable rate of oxidative metabolism, taken as the mean torque over the last 12 contractions. Surface electromyography was recorded continuously as a measure of muscle activation. Results: Mean torque (61 ± 11 vs. 58 ± 14 % pre-exercise MVC) and CT (44 ± 13 vs. 40 ± 15 % pre-exercise MVC) were greater in the acetaminophen trial compared to placebo (both P0.05). However, the decline in electromyography amplitude was attenuated in the acetaminophen trial, with electromyography amplitude being greater compared to placebo from 210 s onwards (P<0.05). Conclusion: These findings indicate that acute acetaminophen ingestion might be ergogenic by increasing CT and preserving muscle activation during high-19 intensity exercise

Acetaminophen ingestion improves muscle activation and performance during a 3-min all-out cycling test

Purpose: Acute acetaminophen (ACT) ingestion has been shown to enhance cycling time-trial performance. The purpose of this study was to assess whether ACT ingestion enhances muscle activation and critical power (CP) during maximal cycling exercise. Methods: Sixteen active male participants completed two 3-min all-out tests against a fixed resistance on an electronically-braked cycle ergometer 60 minutes following ingestion of 1 g ACT or placebo (maltodextrin, PL). CP was estimated as the mean power output over the final 30 s of the test and W′ (the curvature constant of the power-duration relationship) was estimated as the work done above CP. The femoral nerve was stimulated every 30 s to measure membrane excitability (M-wave) and surface electromyography (EMGRMS) was recorded continuously to infer muscle activation. Results: Compared to PL, ACT ingestion increased CP (ACT: 297 ± 32 vs PL: 288 ± 31 W, PRMS amplitude declined throughout the 3-min protocol in both PL and ACT conditions; however, the decline in EMGRMS was attenuated in the ACT condition, with the EMGRMS amplitude being greater compared to PL over the last 60 s of the test (P=0.04). Conclusion: These findings indicate that acute ACT ingestion might increase performance and CP during maximal cycling exercise by enhancing muscle activation

Acute ibuprofen ingestion does not attenuate fatigue during maximal intermittent knee extensor or all-out cycling exercise

Purpose: Recent research suggests that acute consumption of pharmacological analgesics can improve exercise performance, but the ergogenic potential of ibuprofen (IBP) administration is poorly understood. This study tested the hypothesis that IBP administration would enhance maximal exercise performance. Methods: In one study, 13 physically active males completed 60 × 3-s maximum voluntary contractions (MVC) of the knee extensors interspersed with a 2-s passive recovery period, on two occasions, with the critical torque (CT) estimated as the mean torque over the last 12 contractions (part A). In another study, 16 active males completed two 3-min all-out tests against a fixed resistance on an electrically-braked cycle ergometer with the critical power (CP) estimated from the mean power output over the final 30-s of the test (part B). All tests were completed 60 min after ingesting maltodextrin (placebo, PL) or 400 mg of IBP. Peripheral nerve stimulation was administered at regular intervals and electromyography was measured throughout. Results: For part A, mean torque (IBP: 60±12 vs. PL: 58±14% of pre-exercise MVC) and CT (IBP: 40±15 vs. PL: 41±16% of pre-exercise MVC) were not different between conditions (P>0.05). For part B, end-test power output (IBP: 292±28 W vs PL: 288±31 W) and work done (IBP: 65.9±5.9kJ vs PL: 65.4±6.4kJ) during the 3-min all-out cycling tests were not different between conditions (all P>0.05). For both studies, neuromuscular fatigue declined at a similar rate in both conditions (P>0.05). Conclusion: Acute ingestion of 400 mg IBP does not improve single-leg or maximal cycling performance in healthy humans

Contralateral fatigue during severe-intensity single-leg exercise: influence of acute acetaminophen ingestion

Exhaustive single-leg exercise has been suggested to reduce time to task failure (Tlim) during subsequent exercise in the contralateral leg by exacerbating central fatigue development. We investigated the influence of acetaminophen (ACT), an analgesic which may blunt central fatigue development, on Tlim during single-leg exercise completed both with, and without, prior fatiguing exercise of the contralateral leg. Fourteen recreationally-active men performed single-leg, severe-intensity knee extensor exercise to Tlim on the left (Leg1) and right (Leg2) legs without prior contralateral fatigue, and on Leg2 immediately following Leg1 (Leg2- CONTRA). The tests were completed following ingestion of 1 g ACT or maltodextrin (placebo) capsules. Intramuscular phosphorous-containing metabolites and substrates, and muscle activation, were assessed using 31 P-MRS and electromyography, respectively. Tlim was not different between the Leg1ACT and Leg1PL conditions (402 ± 101 vs. 390 ± 106 s; P=0.11). There was also no difference in Tlim between Leg2ACT-CONTRA and Leg2PL-CONTRA (324 ± 85 vs. 311 ± 92 s; P=0.10), but Tlim was shorter in these tests compared to Leg2CON (385 ± 104 s; both P<0.05). There were no differences in intramuscular phosphorous-containing metabolites and substrates, or muscle activation, between the Leg1ACT and Leg1PL or the Leg2ACT-CONTRA and Leg2PL-CONTRA conditions (all P>0.05). These findings suggest that levels of metabolic perturbation and muscle activation are not different at task failure during single leg severe-intensity knee extensor exercise completed with or without prior fatiguing exercise of the contralateral leg. Despite the existence of contralateral fatigue, ACT ingestion did not alter neuromuscular responses or exercise performance

The effects of β-alanine supplementation on muscle pH and the power-duration relationship during high-intensity exercise

Purpose: To investigate the influence of β-alanine (BA) supplementation on muscle carnosine content, muscle pH and the power-duration relationship (i.e., critical power and W′). Methods: In a double-blind, randomized, placebo-controlled study, 20 recreationally-active males (22 ± 3 y, VO˙2peak 3.73 ± 0.44 L·min−1) ingested either BA (6.4 g/d for 28 d) or placebo (PL) (6.4 g/d) for 28 d. Subjects completed an incremental test and two 3-min all-out tests separated by 1-min on a cycle ergometer pre- and post-supplementation. Muscle pH was assessed using 31P-magnetic resonance spectroscopy (MRS) during incremental (INC KEE) and intermittent knee-extension exercise (INT KEE). Muscle carnosine content was determined using 1H-MRS. Results: There were no differences in the change in muscle carnosine content from pre- to post-intervention (PL: 1 ± 16% vs. BA: −4 ± 25%) or in muscle pH during INC KEE or INT KEE (P > 0.05) between PL and BA, but blood pH (PL: −0.06 ± 0.10 vs. BA: 0.09 ± 0.13) during the incremental test was elevated post-supplementation in the BA group only (P < 0.05). The changes from pre- to post-supplementation in critical power (PL: −8 ± 18 W vs. BA: −6 ± 17 W) and W′ (PL: 1.8 ± 3.3 kJ vs. BA: 1.5 ± 1.7 kJ) were not different between groups. No relationships were detected between muscle carnosine content and indices of exercise performance. Conclusions: BA supplementation had no significant effect on muscle carnosine content and no influence on intramuscular pH during incremental or high-intensity intermittent knee-extension exercise. The small increase in blood pH following BA supplementation was not sufficient to significantly alter the power-duration relationship or exercise performance

Dietary nitrate supplementation attenuates the reduction in exercise tolerance following blood donation

Dietary nitrate supplementation attenuates the reduction in exercise tolerance following blood donatio

Dietary nitrate supplementation improves sprint and high-intensity intermittent running performance

Dietary nitrate supplementation improves sprint and high-intensity intermittent running performanc