Reliability of sprint test indices in well-trained cyclists

Flattened cola improves high-intensity interval performance in competitive cyclists

PURPOSE

Some cyclists consume flattened cola during competitive events, but limited research has investigated if cola beverages elicit ergogenic effects, particularly on high-intensity exercise performance. Whether the potentially beneficial effects of cola are due to the caffeine and/or the carbohydrate content is also unclear. This study assessed the ergogenic effects of different cola beverages on performance during a constant power bout (CPB) and subsequent high-intensity interval efforts in competitive cyclists.

METHODS

In a randomized, double-blind, cross-over design, competitive cyclists (n = 13; [Formula: see text]O_2max 65.7 ± 5.9 ml kg^-1 min^-1) completed a 45-min CPB at 69% of maximum workload (W_max), followed by four maximal 1-min high-intensity intervals (HII) against a resistance of 0.5 N kg^-1. Participants consumed 16 ml kg^-1 total (intermittantly at four time points) of flattened decaffinated diet cola (PLA), caffeinated diet cola (CAF) or cola containing caffeine and carbohydrates (CAF + CHO).

RESULTS

During the CPB, ratings of perceived exertion were lower in the CAF + CHO and CAF conditions compared to PLA (both, P < 0.04). Compared to PLA, CAF + CHO and CAF similarly increased (all, P < 0.049) mean power (CAF + CHO: 448 ± 51 W; CAF: 448 ± 50 W; PLA: 434 ± 57 W), minimum power (CAF + CHO: 353 ± 45 W; CAF: 352 ± 51 W; PLA: 324 ± 49 W) and total work (CAF + CHO: 26.9 ± 3.1 kJ; CAF: 26.9 ± 3.0 kJ; PLA: 26.0 ± 3.4 kJ), but not peak power (CAF + CHO: 692 ± 117 W; CAF: 674 ± 114 W; PLA: 670 ± 113 W; all, P > 0.57) during the HII.

CONCLUSION

Cola containing caffeine with or without carbohydrates favorably influenced perceived effort during the CPB and enhanced mean and minimum power during repeated maximal intervals. We provide evidence supporting the consumption of commercially available cola for high-intensity cycling in competitive cyclists.

Effects of load on wingate test performances and reliability

The purpose of this study was to examine the effects of 2 braking forces (8.7 and 11% of body mass, BM) on Wingate test performance, peak lactate ([La]pk), peak heart rate (HRpk), and rate of perceived exertion (RPE). Sixteen male physical education students (age: 22.7 ± 1.3 years, height: 1.81 ± 0.07 m, BM: 74.3 ± 9.6 kg) performed, in a randomized order, 2 Wingate tests at 8.7% BM and 2 Wingate tests at 11% BM on a Monark cycle ergometer on 4 separate sessions. The results showed that the reliability level of mechanical measures was not affected by the braking force and was relatively similar for each variable in both braking forces (0.886 < ICC < 0.985). In addition, peak power, mean power, fatigue slope, and RPE were significantly higher (8.2, 7.0, 11.9, and 4.1%, respectively, all < 0.05) using a braking force of 11% BM compared with 8.7% BM, whereas there was no significant effect of braking force on [La]pk and HRpk. In conclusion, the results of this study suggested that the reliability of the Wingate test does not depend on the used load, and a braking force of 11% BM is more optimal for power output during Wingate test in active adults.

Effects of negative air ions on oxygen uptake kinetics, recovery and performance in exercise: a randomized, double-blinded study

Limited research has suggested that acute exposure to negatively charged ions may enhance cardio-respiratory function, aerobic metabolism and recovery following exercise. To test the physiological effects of negatively charged air ions, 14 trained males (age: 32 ± 7 years; VO2max: 57 ± 7 mL min(-1) kg(-1)) were exposed for 20 min to either a high-concentration of air ions (ION: 220 ± 30 × 10(3) ions cm(-3)) or normal room conditions (PLA: 0.1 ± 0.06 × 10(3) ions cm(-3)) in an ionization chamber in a double-blinded, randomized order, prior to performing: (1) a bout of severe-intensity cycling exercise for determining the time constant of the phase II VO2 response (τ) and the magnitude of the VO2 slow component (SC); and (2) a 30-s Wingate test that was preceded by three 30-s Wingate tests to measure plasma [adrenaline] (ADR), [nor-adrenaline] (N-ADR) and blood [lactate] (B(Lac)) over 20 min during recovery in the ionization chamber. There was no difference between ION and PLA for the phase II VO2 τ (32 ± 14 s vs. 32 ± 14 s; P = 0.7) or VO2 SC (404 ± 214 mL vs 482 ± 217 mL; P = 0.17). No differences between ION and PLA were observed at any time-point for ADR, N-ADR and B(Lac) as well as on peak and mean power output during the Wingate tests (all P > 0.05). A high-concentration of negatively charged air ions had no effect on aerobic metabolism during severe-intensity exercise or on performance or the recovery of the adrenergic and metabolic responses after repeated-sprint exercise in trained athletes.

The reliability of a 30-s sprint test on the Wattbike cycle ergometer

PURPOSE

To determine the reliability of a 30-s sprint cycle test on the Wattbike cycle ergometer.

METHODS

Over 3 consecutive weeks, 11 highly trained cyclists (mean ± SD; age 31 ± 6 y, mass 74.6 ± 10.6 kg, height 180.5 ± 8.1cm) completed four 30-s maximal sprints on a Wattbike ergometer after a standardized warm-up. The sprint test implemented a "rolling start" that consisted of a 60-s preload (at an intensity of 4.5 W/kg) before the 30-s maximal sprint. Variables determined across the duration of the sprint were peak power (Wpeak), mean power (Wmean), W/kg, mean cadence (rpm), maximum heart rate (n = 10), and postexercise blood lactate.

RESULTS

The average intraclass correlation coefficients between trials (2v1, 3v2, 4v3, 4v1) were Wpeak .97 (90%CI .94-.99), Wmean .99 (90%CI .97-1.00), W/kg .96 (90%CI .91-.98), mean cadence .96 (90%CI .92-.99), maximum heart rate .99 (90%CI .97-.99), and postexercise blood lactate .94 (90%CI .87-.98). The average typical error of measurement (expressed as a CV% and absolute value between trials-2v1, 3v2, 4v3, 4v1) was Wpeak 4.9%, 52.7 W; Wmean 2.4%, 19.2 W; W/kg 2.3%, 0.18 W/kg; mean cadence 1.4%, 1.6 rpm; maximum heart rate 0.9%, 1.6 beats/min; and postexercise blood lactate 4.6%, 0.48 mmol/L.

CONCLUSION

A 30-s sprint test on the Wattbike cycle ergometer is highly reproducible in trained cyclists.

Sex differences of intermittent elbow flexion power using various loads

This study was designed to clarify a sex difference in muscle power output properties by intermittent elbow flexion using various loads. 10 young males and 10 young females performed intermittent elbow flexion power outputs at 30 times x min.(-1) for 1 min. using 30%, 40%, and 50% MVC loads. For both sexes, the decreasing peak power showed a similar trend between trials at all loads, and the reliability of each power parameter was good. The power outputs decreased largely with increasing load mass, and the power output in 50% MVC for males markedly decreased to the same level as that during the final phase in 30% MVC. Although the absolute value of regression coefficients for males became significantly larger with increasing load mass, that for females showed a significant difference only between 30% and 50% MVC. In 50% MVC, a large decrease for males was observed. Maximal peak power outputs were significantly larger with increasing load mass for both sexes, but for males more than for females. In both sexes, there were no significant differences among final powers of each load mass, and between total powers of 40% and 50% MVC. For the sum of every 5 consecutive power outputs, males showed significant differences between 30% and 40% MVC in all periods after the 6th contraction, but females did not and also between 30% and 50% MVC in periods after the 16th contraction. In conclusion, it is considered that power outputs in the latter phases in 50% MVC are affected largely by muscle fatigue, and an intermittent power output test with 50% MVC can measure sustained power (fatigue resistance) in the latter phases, but there is a sex difference in the tendency to decrease.

Changes in Elbow Flexor Power with Intermittent Contractions and Various Loads

This study examined intermittent elbow flexion every 2 see. for 1 min. using various loads to study the properties of muscle power output and their relationship to peak power, defined as the maximum power output. 18 young men performed intermittent explosive elbow flexion (30 times × min.−1) using 30%, 40%, and 50% maximal voluntary contraction (MVC). The power outputs at 30% and 40% MVC slightly decreased (rate of decrease from peak power to average power output during the 26 to 30 contractions was about 5%). However, at 50% MVC, there was a marked decrease (33.6%). Power output for 8 contractions was significantly larger at 50% MVC than at 30% and 40% MVC, but after 9 contractions there was no significant difference between 40% and 50% MVC. In addition, after 27 contractions, 40% MVC was significantly larger than 30% and 50% MVC. That is, the tendency for power output to decrease differed among the various loads. The rate of decrease of power outputs showed no significant correlation with peak power for each load. Therefore, the rate of decrease or power output in intermittent contractions may help sustain the power output and cannot be evaluated as accurately as peak power.

Placebo effects of caffeine on cycling performance

PURPOSE

The placebo effect-a change attributable only to an individual's belief in the efficacy of a treatment-might provide a worthwhile improvement in physical performance. Although sports scientists account for placebo effects by blinding subjects to treatments, little research has sought to quantify and explain the effect itself. The present study explored the placebo effect in laboratory cycling performance using quantitative and qualitative methods.

METHOD

Six well-trained male cyclists undertook two baseline and three experimental 10-km time trials. Subjects were informed that in the experimental trials they would each receive a placebo, 4.5 mg.kg caffeine, and 9.0 mg.kg caffeine, randomly assigned. However, placebos were administered in all experimental conditions. Semistructured interviews were also conducted to explore subjects' experience of the effects of the capsules before and after revealing the deception.

RESULTS

A likely trivial increase in mean power of 1.0% over baseline was associated with experimental trials (95% confidence limits, -1.4 to 3.6%), rising to a likely beneficial 2.2% increase in power associated with experimental trials in which subjects believed they had ingested caffeine (-0.8 to 5.4%). A dose-response relationship was evident in experimental trials, with subjects producing 1.4% less power than at baseline when they believed they had ingested a placebo (-4.6 to 1.9%), 1.3% more power than at baseline when they believed they had ingested 4.5 mg.kg caffeine (-1.4 to 4.1%), and 3.1% more power than at baseline when they believed they had ingested 9.0 mg.kg caffeine (-0.4 to 6.7%). All subjects reported caffeine-related symptoms.

CONCLUSIONS

Quantitative and qualitative data suggest that placebo effects are associated with the administration of caffeine and that these effects may directly or indirectly enhance performance in well-trained cyclists.