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Purpose To compare methods of relative intensity prescription for their ability to normalise performance (i.e., time to exhaustion), physiological, and perceptual responses to high-intensity interval training (HIIT) between individuals. Methods Sixteen male and two female cyclists (age: 38 ± 11 years, height: 177 ± 7 cm, body mass: 71.6 ± 7.9 kg, maximal oxygen uptake ($$ \dot{\text{V}} $$ V ˙ O2max): 54.3 ± 8.9 ml·kg−1 min−1) initially undertook an incremental test to exhaustion, a 3 min all-out test, and a 20 min time-trial to determine prescription benchmarks. Then, four HIIT sessions (4 min on, 2 min off) were each performed to exhaustion at: the work rate associated with the gas exchange threshold ($$ \dot{\text{W}} $$ W ˙ GET) plus 70% of the difference between $$ \dot{\text{W}} $$ W ˙ GET and the work rate associated with $$ \dot{\text{V}} $$ V ˙ O2max; 85% of the maximal work rate of the incremental test (85%$$ \dot{\text{W}} $$ W ˙ max); 120% of the mean work rate of the 20 min time-trial (120%TT); and the work rate predicted to expend, in 4 min, 80% of the work capacity above critical power. Acute HIIT responses were modelled with participant as a random effect to provide estimates of inter-individual variability. Results For all dependent variables, the magnitude of inter-individual variability was high, and confidence intervals overlapped substantially, indicating that the relative intensity normalisation methods were similarly poor. Inter-individual coefficients of variation for time to exhaustion varied from 44.2% (85%$$ \dot{\text{W}} $$ W ˙ max) to 59.1% (120%TT), making it difficult to predict acute HIIT responses for an individual. Conclusion The present study suggests that the methods of intensity prescription investigated do not normalise acute responses to HIIT between individuals.

Purpose: Professional football players experience both physical and mental fatigue (MF). The main aims of this randomized crossover study were to investigate the effect of MF on repeated-sprint ability (RSA) and the effects of both physical fatigue and MF on psychomotor vigilance. Methods: Seventeen male professional football players performed 10 maximal 20-m shuttle sprints interspaced by incomplete recovery (RSA test). Running speed, heart rate, brain oxygenation, and rating of perceived exertion were monitored during each sprint. The RSA test was preceded by either a 30-minute Stroop task to induce MF or by watching a documentary for 30 minutes (control [CON]) in a randomized counterbalanced order. Participants performed a psychomotor vigilance test at baseline, after the cognitive task (MF or CON), and after the RSA test. Results: Heart rate and rating of perceived exertion significantly increased, while running speed and brain oxygenation significantly decreased over the repeated sprints (P P = .001). Response speed during the psychomotor vigilance test declined after the RSA test in both conditions (P P = .012). Conclusions: MF does not reduce RSA. However, the results of this study suggest that physical fatigue and MF have negative and cumulative effects on psychomotor vigilance. Therefore, strategies to reduce both physical fatigue and MF should be implemented in professional football players.

The aim of this study was to examine differences in cycling efficiency between competitive male and female cyclists. Thirteen trained male (mean ± SD: 34 ± 8 yr, 74.1 ± 6.0 kg, Maximum Aerobic Power (MAP) 414 ± 40 W, VO2max 61.3 ± 5.4 ml·kg-1·min-1) and 13 trained female (34 ± 9 yr, 60.1 ± 5.2 kg, MAP 293 ± 22 W, VO2max 48.9 ± 6.1 ml·kg-1·min-1) competitive cyclists completed a cycling test to ascertain their gross efficiency (GE). Leg and lean leg volume of all cyclists was also measured. Calculated GE was significantly higher in female cyclists at 150W (22.5 ± 2.1 vs 19.9 ± 1. 8%; p < 0.01) and 180W (22.3 ± 1.8 vs 20.4 ± 1.5%; p = 0.01). Cadence was not significantly different between the groups (88 ± 6 vs 91 ± 5 rev·min-1). Lean leg volume was significantly lower for female cyclists (4.04 ± 0.5 vs 5.51 ± 0.8 dm3; p < 0.01) and was inversely related to GE in both groups at 150 and 180W (r = -0.59 and -0.58; p < 0.05). Lean leg volume was shown to account for the differences in GE between the males and females. During an "unloaded" pedalling condition, male cyclists had a significantly higher O2 cost than female cyclists (1.0 ± 0.1 vs 0.7 ± 0.1 L·min-1; p < 0.01), indicative of a greater non-propulsive cost of cycling. These results suggest that differences in efficiency between trained male and female cyclists can be partly accounted for by sex-specific variation in lean leg volume

The impact of different intensity training on cycling efficiency in competitive cyclists is unknown. Twenty-nine endurance-trained competitive male cyclists completed 3 laboratory visits during a 12-week training period. At each visit, their cycling efficiency and maximal oxygen uptake were determined. After the first visit, cyclists were randomly split into 2 groups (A and B). Over the first 6 weeks, between tests 1 and 2, group A was prescribed specific high-intensity training sessions, whereas group B was restricted in the amount of intensive work undertaken. After test 2 and for the second 6-week period, group B was allowed to conduct high-intensity training. Gross efficiency (GE) increased in group A (+1.6 ± 1.4%; p < 0.05) following the high-intensity training, whereas no significant change was seen in group B (+0.1 ± 0.7%; p > 0.05). Group B cyclists increased their GE between tests 2 and 3 (+1.4 ± 0.8%; p < 0.05) but no changes in GE were observed in group A over this period (+0.4 ± 0.4%; p > 0.05). Delta efficiency (DE) did not change significantly in either group across the study period. This study demonstrates that GE is increased following high-intensity training in competitive male cyclists after 12 weeks.

The aim of this study was to evaluate the impact of a novel crank system on laboratory time-trial cycling performance. The Rotor system makes each pedal independent from the other so that the cranks are no longer fixed at 180°. Twelve male competitive but non-elite cyclists (mean ± s: 35 ± 7 yr, Wmax = 363 ± 38 W, VO2peak = 4.5 ± 0.3 L·min(-1)) completed 6-weeks of their normal training using either a conventional (CON) or the novel Rotor (ROT) pedal system. All participants then completed two 40.23-km time-trials on an air-braked ergometer, one using CON and one using ROT. Mean performance speeds were not different between trials (CON = 41.7 km·h(-1) vs. ROT = 41.6 km·h(-1), P0.05). Indeed, the pedal system used during the time-trials had no impact on any of the measured variables (power output, cadence, heart rate, VO2, RER, gross efficiency). Furthermore, the ANOVA identified no significant interaction effect between main effects (Time-trial crank system*Training crank system, P0.05). To the authors' knowledge, this is the first study to examine the effects of the Rotor system on endurance performance rather than endurance capacity. These results suggest that the Rotor system has no measurable impact on time-trial performance. However, further studies should examine the importance of the Rotor 'regulation point' and the suggestion that the Rotor system has acute ergogenic effects if used infrequently. Key pointsThe Rotor crank system does not improve gross efficiency in well-trained cyclists.The Rotor crank system has no measurable impact on laboratory 40.23-km time-trial performance.A 6-week period of familiarisation does not increase the effectiveness of the Rotor crank system.

The aim of this study was to examine differences in cycling efficiency between competitive male and female cyclists. Thirteen trained male (mean ± SD: 34 ± 8 yr, 74.1 ± 6.0 kg, Maximum Aerobic Power (MAP) 414 ± 40 W, VO2max 61.3 ± 5.4 ml·kg(-1)·min(-1)) and 13 trained female (34 ± 9 yr, 60.1 ± 5.2 kg, MAP 293 ± 22 W, VO2max 48.9 ± 6.1 ml·kg(-1)·min(-1)) competitive cyclists completed a cycling test to ascertain their gross efficiency (GE). Leg and lean leg volume of all cyclists was also measured. Calculated GE was significantly higher in female cyclists at 150W (22.5 ± 2.1 vs 19.9 ± 1. 8%; p0.01) and 180W (22.3 ± 1.8 vs 20.4 ± 1.5%; p = 0.01). Cadence was not significantly different between the groups (88 ± 6 vs 91 ± 5 rev·min(-1)). Lean leg volume was significantly lower for female cyclists (4.04 ± 0.5 vs 5.51 ± 0.8 dm(3); p0.01) and was inversely related to GE in both groups at 150 and 180W (r = -0.59 and -0.58; p0.05). Lean leg volume was shown to account for the differences in GE between the males and females. During an "unloaded "pedalling condition, male cyclists had a significantly higher O2 cost than female cyclists (1.0 ± 0.1 vs 0.7 ± 0.1 L·min(-1); p0.01), indicative of a greater non-propulsive cost of cycling. These results suggest that differences in efficiency between trained male and female cyclists can be partly accounted for by sex-specific variation in lean leg volume. Key pointsDifferences in GE exist between male and female cyclists.Males have a higher oxygen cost of "unloaded "cycling, as predicted by the intercept of the O2 cost-power output relationshipThis suggests that in addition to work rate, leg volume/mass may be an important determinant of observed differences in oxygen cost and therefore GE, between male and female competitive cyclists.