Gillian McInnes

The Reliability and Validity of Fatigue Measures During Multiple-Sprint Work: An Issue Revisited

Glaister, M, Howatson, G, Pattison, JR, and McInnes, G. The reliability and validity of fatigue measures during multiple-sprint work: an issue revisited. J Strength Cond Res 22(5): 1597-1601, 2008-The ability to repeatedly produce a high-power output or sprint speed is a key fitness component of most field and court sports. The aim of this study was to evaluate the validity and reliability of eight different approaches to quantify this parameter in tests of multiple-sprint performance. Ten physically active men completed two trials of each of two multiple-sprint running protocols with contrasting recovery periods. Protocol 1 consisted of 12 × 30-m sprints repeated every 35 seconds; protocol 2 consisted of 12 × 30-m sprints repeated every 65 seconds. All testing was performed in an indoor sports facility, and sprint times were recorded using twin-beam photocells. All but one of the formulae showed good construct validity, as evidenced by similar within-protocol fatigue scores. However, the assumptions on which many of the formulae were based, combined with poor or inconsistent test-retest reliability (coefficient of variation range: 0.8-145.7%; intraclass correlation coefficient range: 0.09-0.75), suggested many problems regarding logical validity. In line with previous research, the results support the percentage decrement calculation as the most valid and reliable method of quantifying fatigue in tests of multiple-sprint performance.

Caffeine supplementation and multiple sprint running performance.

PURPOSE The aim of this study was to examine the effects of caffeine supplementation on multiple sprint running performance. METHODS Using a randomized double-blind research design, 21 physically active men ingested a gelatin capsule containing either caffeine (5 mg x kg(-1) body mass) or placebo (maltodextrin) 1 h before completing an indoor multiple sprint running trial (12 x 30 m; repeated at 35-s intervals). Venous blood samples were drawn to evaluate plasma caffeine and primary metabolite concentrations. Sprint times were recorded via twin-beam photocells, and earlobe blood samples were drawn to evaluate pretest and posttest lactate concentrations. Heart rate was monitored continuously throughout the tests, with RPE recorded after every third sprint. RESULTS Relative to placebo, caffeine supplementation resulted in a 0.06-s (1.4%) reduction in fastest sprint time (95% likely range = 0.04-0.09 s), which corresponded with a 1.2% increase in fatigue (95% likely range = 0.3-2.2%). Caffeine supplementation also resulted in a 3.4-bpm increase in mean heart rate (95% likely range = 0.1-6.6 bpm) and elevations in pretest (+0.7 mmol x L(-1); 95% likely range = 0.1-1.3 mmol x L(-1)) and posttest (+1.8 mmol x L(-1); 95% likely range = 0.3-3.2 mmol x L(-1)) blood lactate concentrations. In contrast, there was no significant effect of caffeine supplementation on RPE. CONCLUSION Although the effect of recovery duration on caffeine-induced responses to multiple sprint work requires further investigation, the results of the present study show that caffeine has ergogenic properties with the potential to benefit performance in both single and multiple sprint sports.

Familiarization and reliability of multiple sprint running performance indices.

The aims of this study were to evaluate the time-course of the familiarization process associated with a test of multiple sprint running performance and to determine the reliability of various performance indices once familiarization had been established. Eleven physically active men (mean age: 21 ± 2 years) completed 4 multiple sprint running trials (12 X 30 m; repeated at 35-s intervals) with 7 days between trials. All testing was conducted indoors, and times were recorded by twin-beam photocells. Results revealed no apparent learning effects as evidenced by no significant (p > 0.05) between-trial differences in measures of fastest or mean 30-m sprint time. Within-subject test–retest reliability determined over 4 trials by coefficient of variation (CV) and intraclass correlation coefficient (ICC) showed excellent reliability for measures of fastest and mean sprint times (CV range: 1.34–2.24%; ICC range: 0.79–0.94). Pre- and posttrial blood lactate concentrations showed good reliability when judged in context with typical values (CV range: 12.08–18.21%; ICC range: 0.72–0.78). In contrast, and in line with previous research, fatigue data showed much greater variability (CV: 26.43%; ICC: 0.66). The results of this study suggest that high degrees of test–retest reliability can be obtained in many multiple sprint running indices without the need for prior familiarization.

Creatine supplementation and multiple sprint running performance.

The aim of this study was to examine the effects of short-term creatine monohydrate supplementation on multiple sprint running performance. Using a double-blind research design, 42 physically active men completed a series of 3 indoor multiple sprint running trials (15 3 30 m repeated at 35-second intervals). After the first 2 trials (familiarization and baseline), subjects were matched for fatigue score before being randomly assigned to 5 days of either creatine (4·d−1 × 5 g creatine monohydrate 1 1g maltodextrin) or placebo (4·d−1 × 6 g maltodextrin) supplementation. Sprint times were recorded via twin-beam photocells, and earlobe blood samples were drawn to evaluate posttest lactate concentrations. Relative to placebo, creatine supplementation resulted in a 0.7 kg increase in body mass (95% likely range: 0.02 to 1.3 kg) and a 0.4% reduction in body fat (95% likely range: 20.2 to 0.9%). There were no significant (p > 0.05) between-group differences in multiple sprint measures of fastest time, mean time, fatigue, or posttest blood lactate concentration. Despite widespread use as an ergogenic aid in sport, the results of this study suggest that creatine monohydrate supplementation conveys no benefit to multiple sprint running performance.

Caffeine and Sprinting Performance: Dose Responses and Efficacy

Abstract Glaister, M, Patterson, SD, Foley, P, Pedlar, CR, Pattison, JR, and McInnes, G. Caffeine and sprinting performance: dose responses and efficacy. J Strength Cond Res 26(4): 1001–1005, 2012—The aims of this study were to evaluate the effects of caffeine supplementation on sprint cycling performance and to determine if there was a dose-response effect. Using a randomized, double-blind, placebo-controlled design, 17 well-trained men (age: 24 ± 6 years, height: 1.82 ± 0.06 m, and body mass(bm): 82.2 ± 6.9 kg) completed 7 maximal 10-second sprint trials on an electromagnetically braked cycle ergometer. Apart from trial 1 (familiarization), all the trials involved subjects ingesting a gelatine capsule containing either caffeine or placebo (maltodextrin) 1 hour before each sprint. To examine dose-response effects, caffeine doses of 2, 4, 6, 8, and 10 mg·kg bm−1 were used. There were no significant (p ≥ 0.05) differences in baseline measures of plasma caffeine concentration before each trial (grand mean: 0.14 ± 0.28 &mgr;g·ml−1). There was, however, a significant supplement × time interaction (p < 0.001), with larger caffeine doses producing higher postsupplementation plasma caffeine levels. In comparison with placebo, caffeine had no significant effect on peak power (p = 0.11), mean power (p = 0.55), or time to peak power (p = 0.17). There was also no significant effect of supplementation on pretrial blood lactate (p = 0.58), but there was a significant time effect (p = 0.001), with blood lactate reducing over the 50 minute postsupplementation rest period from 1.29 ± 0.36 to 1.06 ± 0.33 mmol·L−1. The results of this study show that caffeine supplementation has no effect on short-duration sprint cycling performance, irrespective of the dosage used.

Caffeine supplementation and peak anaerobic power output

Abstract The aim of this study was to investigate the effects of caffeine supplementation on peak anaerobic power output (Wmax). Using a counterbalanced, randomised, double-blind, placebo-controlled design, 14 well-trained men completed three trials of a protocol consisting of a series of 6-s cycle ergometer sprints, separated by 5-min passive recovery periods. Sprints were performed at progressively increasing torque factors to determine the peak power/torque relationship and Wmax. Apart from Trial 1 (familiarisation), participants ingested a capsule containing 5 mg·kg−1 of caffeine or placebo, one hour before each trial. The effects of caffeine on blood lactate were investigated using capillary samples taken after each sprint. The torque factor which produced Wmax was not significantly different (p ≥ 0.05) between the caffeine (1.15 ± 0.08 N·m·kg−1) and placebo (1.13 ± 0.10 N·m·kg−1) trials. There was, however, a significant effect (p < 0.05) of supplementation on Wmax, with caffeine producing a higher value (1885 ± 303 W) than placebo (1835 ± 290 W). Analysis of the blood lactate data revealed a significant (p < 0.05) torque factor × supplement interaction with values being significantly higher from the sixth sprint (torque factor 1.0 N·m·kg−1) onwards following caffeine supplementation. The results of this study confirm previous reports that caffeine supplementation significantly increases blood lactate and Wmax. These findings may explain why the majority of previous studies, which have used fixed-torque factors of around 0.75 N·m·kg−1 and thereby failing to elicit Wmax, have failed to find an effect of caffeine on sprinting performance.

Perceptual and Physiological Responses to Recovery from a Maximal 30-Second Sprint

Abstract Glaister, M, Pattison, JR, Dancy, B, and McInnes, G. Perceptual and physiological responses to recovery from a maximal 30-second sprint. J Strength Cond Res 26(10): 2850–2857, 2012—The aims of this study were to evaluate perceptions of postexercise recovery and to compare patterns of perceived recovery with those of several potential mediating physiological variables. Seventeen well-trained men (age: 22 ± 4 years; height: 1.83 ± 0.05 m; body mass: 78.9 ± 7.6 kg; and body fat: 11.1 ± 2.2%) completed 10 sprint trials on an electromagnetically braked cycle ergometer. Trial 1 evaluated peak power via a 5-second sprint. The remaining trials evaluated (a) the recovery of peak power after a maximal 30-second sprint using rest intervals of 5, 10, 20, 40, 80, and 160 seconds; (b) perceived recovery via visual analog scales; and (c) physiological responses during recovery. The time point in recovery at which individuals perceived they had fully recovered was 163.3 ± 57.5 seconds. Power output at that same time point was 83.6 ± 5.2% of peak power. There were no significant differences between perceived recovery and the recovery processes of V[Combining Dot Above]O2 or minute ventilation (VE). Despite differences in the time courses of perceived recovery and the recovery of power output, individuals were able to closely predict full recovery without the need for external timepieces. Moreover, the time course of perceived recovery is similar to that of V[Combining Dot Above]O2 and VE.