Active recovery, training status, muscle metabolism and repeated sprint performance

This thesis found that light exercise between repeated sprints improved performance in a subsequent bout. This was attributed to a reduction in potentially fatiguing by-products within the muscle and an increased aerobic metabolism in the second sprint.

Effects of starting strategy on 5-min cycling time-trial performance

The importance of pacing for middle-distance performance is well recognized, yet previous research has produced equivocal results. Twenty-six trained male cyclists ( V O_2peak 62.8+5.9 ml ·kg^-1 · min^-1· maximal aerobic power output 340+43 W; mean+s) performed three cycling time-trials where the total external work (102.7+13.7 kJ) for each trial was identical to the best of two 5-min habituation trials. Markers of aerobic and anaerobic metabolism were assessed in 12 participants. Power output during the first quarter of the time-trials was fixed to control external mechanical work done (25.7+3.4 kJ) and induce fast-, even-, and slow-starting strategies (60, 75, and 90 s, respectively). Finishing times for the fast-start time-trial (4:53+0:11 min:s) were shorter than for the even-start (5:04+0:11 min:s; 95% CI=5 to 18 s, effect size=0.65, P 50.001) and slow-start time-trial (5:09+0:11 min:s; 95% CI=7 to 24 s, effect size=1.00, P 50.001). Mean VO₂ during the fast-start trials (4.31+0.51 litres · min^-1) was 0.18+0.19 litres · min^-1 (95% CI=0.07 to 0.30 litres · min^-1, effect size=0.94, P =0.003) higher than the even- and 0.18+0.20 litres · min^-1 (95% CI=0.5 to 0.30 litres · min^-1, effect size=0.86, P =0.007) higher than the slow-start time-trial. Oxygen deficit was greatest during the first quarter of the fast-start trial but was lower than the even- and slow-start trials during the second quarter of the trial. Blood lactate and pH were similar between the three trials. In conclusion, performance during a 5-min cycling time-trial was improved with the adoption of a fast- rather than an even- or slow-starting strategy.

Sprint cycling performance is maintained with short-term contrast water immersion

Purpose: Given the widespread use of water immersion during recovery from exercise, we aimed to investigate the effect of contrast water immersion on recovery of sprint cycling performance, HR and, blood lactate.

Methods: Two groups completed high-intensity sprint exercise before and after a 30-min randomized recovery. The Wingate group (n = 8) performed 3 x 30-s Wingate tests (4-min rest periods). The repeated intermittent sprint group (n = 8) cycled for alternating 30-s periods at 40% of predetermined maximum power and 120% maximum power, until exhaustion. Both groups completed three trials using a different recovery treatment for each trial (balanced randomized application). Recovery treatments were passive rest, 1:1 contrast water immersion (2.5 min of cold (8-C) to 2.5 min of hot (40-C)), and 1:4 contrast water immersion (1 min of cold to 4 min of hot). Blood lactate and HR were recorded throughout, and peak power and total work for pre- and postrecovery Wingate performance and exercise time and total work for repeated sprinting were recorded.

Results: Recovery of Wingate peak power was 8% greater after 1:4 contrast water immersion than after passive rest, whereas both contrast water immersion ratios provided a greater recovery of exercise time (È10%) and total work (È14%) for repeated sprinting than for passive rest. Blood lactate was similar between trials. Compared with passive rest, HR initially declined more slowly during contrast water immersion but increased with each transition to a cold immersion phase.

Conclusions: These data support contrast water immersion being effective in maintaining performance during a short-term recovery from sprint exercise. This effect needs further investigation but is likely explained by cardiovascular mechanisms, shown here by an elevation in HR upon each cold immersion.

Physiological responses of elite junior Australian Rules footballers during match-play

Australian Football (AF) is Australia's major football code. Despite research in other football codes, to date, no data has been published on the physiological responses of AF players during match play. Fifteen athletes (17.28 ± 0.76 yrs) participated in four pre-season matches, sanctioned by Australian Football League (AFL) Victoria, investigating Heart Rate (HR), Blood Lactate (BLa), Core Temperature (Tcore), and Hydration status. Match HR was measured continuously using HR monitors. BLa was measured via finger prick lancet at the end of each quarter of play. Tcore was measured by use of ingestible temperature sensor and measured wirelessly at the end of each quarter of play. Hydration status was measured using refractometry, measuring urine specific gravity, and body weight pre and post-match. Environmental conditions were measured continuously during matches. Results of HR responses showed a high exertion of players in the 85-95% maximum HR range. Elevated mean BLa levels, compared to rest, were observed in all players over the duration of the matches (p = 0.007). Mean Tcore rose 0.68 °C between start and end of matches. Mean USG increased between 0.008 g/ml (p = 0.001) with mean body weight decreasing 1.88 kg (p = 0.001). This study illustrates physiological responses in junior AF players playing in the heat as well as providing physiological data for consideration by AF coaching staff when developing specific training programs. Continued research should consider physiological measurements under varying environments, and at all playing levels of AF, to ascertain full physiological responses during AF matches.

Adrenaline and glycogenolysis in skeletal muscle during exercise : a study in adrenalectomised humans

1. The role of adrenaline in regulating muscle glycogenolysis and hormonesensitive lipase (HSL) activity during exercise was examined in six adrenalinedeficient bilaterally adrenalectomised, adrenocorticohormonalsubstituted humans (Adr) and in six healthy control individuals (Con).

2. Subjects cycled for 45 min at •70% maximal pulmonary Oμ uptake (ýO2,max) followed by 15 min at •86% ýO2,max either without (−Adr and Con) or with (+Adr) adrenaline infusion that elevated plasma adrenaline levels (45 min, 4·49 ± 0·69 nmol l¢; 60 min, 12·41 ± 1·80 nmol l¢). Muscle samples were obtained at 0, 45 and 60 min of exercise.

3. In −Adr and Con, muscle glycogen was similar at rest (−Adr, 409 ± 19 mmol (kg dry wt)¢; Con, 453 ± 24 mmol (kg dry wt)¢) and following exercise (−Adr, 237 ± 52 mmol (kg dry wt)¢; Con, 227 ± 50 mmol (kg dry wt)¢). Muscle lactate, glucose6phosphate and glucose were similar in −Adr and Con, whereas glycogen phosphorylase (aÏa + b ² 100 %) and HSL (% phosphorylated) activities increased during exercise in Con only. Adrenaline infusion increased activities of phosphorylase and HSL as well as blood lactate concentrations compared with those in −Adr, but did not enhance glycogen breakdown (+Adr, glycogen following exercise: 274 ± 55 mmol (kg dry wt)¢) in contracting muscle.

4. The present findings demonstrate that during exercise muscle glycogenolysis can occur in the absence of adrenaline, and that adrenaline does not enhance muscle glycogenolysis in exercising adrenalectomised subjects. Although adrenaline increases the glycogen phosphorylase activity it is not essential for glycogen breakdown in contracting muscle. Finally, a novel finding is that the activity of HSL in human muscle is increased in exercising man and this is due, at least partly, to stimulation by adrenaline.

Using recovery modalities between training sessions in elite athletes: does it help?

Achieving an appropriate balance between training and competition stresses and recovery is important in maximising the performance of athletes. A wide range of recovery modalities are now used as integral parts of the training programmes of elite athletes to help attain this balance. This review examined the evidence available as to the efficacy of these recovery modalities in enhancing between-training session recovery in elite athletes. Recovery modalities have largely been investigated with regard to their ability to enhance the rate of blood lactate removal following high-intensity exercise or to reduce the severity and duration of exercise-induced muscle injury and delayed onset muscle soreness (DOMS). Neither of these reflects the circumstances of between-training session recovery in elite athletes. After high-intensity exercise, rest alone will return blood lactate to baseline levels well within the normal time period between the training sessions of athletes. The majority of studies examining exercise-induced muscle injury and DOMS have used untrained subjects undertaking large amounts of unfamiliar eccentric exercise. This model is unlikely to closely reflect the circumstances of elite athletes. Even without considering the above limitations, there is no substantial scientific evidence to support the use of the recovery modalities reviewed to enhance the between-training session recovery of elite athletes. Modalities reviewed were massage, active recovery, cryotherapy, contrast temperature water immersion therapy, hyperbaric oxygen therapy, nonsteroidal anti-inflammatory drugs, compression garments, stretching, electromyostimulation and combination modalities. Experimental models designed to reflect the circumstances of elite athletes are needed to further investigate the efficacy of various recovery modalities for elite athletes. Other potentially important factors associated with recovery, such as the rate of post-exercise glycogen synthesis and the role of inflammation in the recovery and adaptation process, also need to be considered in this future assessment.

The design and implementation of a novel method for quantifying training loads in elite rowing: the T2minute method

Introduction: A systematic approach to managing the training of elite athletes is supported by accurate training load measurement. However, quantifying the training of elite Australian rowers is complex due to unique challenges: 1) the multi-centre, multi-state structure of the national program; 2) the variety of training undertaken, incorporating rowing-specific and non-specific modalities, with continuous and interval efforts that span the full intensity spectrum; and 3) the limitations of existing quantification methods for capturing total training loads undertaken from varied training. These challenges highlighted a need to create a consistent, location-independent framework for prescribing training in elite rowing, with a capacity to account for varied training. Methods: An in-house proprietary measure (the T2minute method) was developed at the National Rowing Centre of Excellence (NRCE), as a collaborative project between sport scientists and national squad coaches. The design phase was informed by assessments of the existing training measures, and built upon standardised intensity zones established at the Australian Institute of Sport. A common measurement unit was chosen: one T2minute equates to one minute of on-water single scull rowing at T2 intensity (∼60–72% VO2max). Each intensity zone was assigned a weighting factor according to the curvilinear relationship between power output, intensity, and blood lactate response. Each training mode was assigned a weighting factor based on whether coaches perceived it to be “harder” or “easier” than onwater rowing. With coaches’ feedback, the method was refined over a period of five months. The T2minute method was implemented as the core framework for prescribing training for elite Australian rowers throughout the 2009–2012 Olympic cycle. Results: The implementation of the T2minute method successfully established consistency with training prescription and monitoring practices within the NRCE high performance program. The national roll out this method has influenced rowing training methodology at elite and sub-elite levels in Australia. Since implementation, the method has undergone scientific validation. Further research is underway, utilising the method to explore complex relationships between rowers’ training and performance outcomes. Conclusion: The T2minute method is a novel approach that allows rowing coaches and sport scientists to utilise one consistent system to quantify load from varied training. Its implementation represents a considerable achievement in establishing a common framework for managing the training process within a complex organisational structure. This collaborative approach used to develop the T2minute method provides unique insight into the important considerations and practical challenges of applying training science to enhance elite sport performance.

Reliability and effect of sodium bicarbonate : buffering and 2000-m rowing performance

Purpose: The aim of this study was to determine the effect and reliability of acute and chronic sodium bicarbonate ingestion for 2000-m rowing ergometer performance (watts) and blood bicarbonate concentration [HCO3 -]. Methods: In a crossover study, 7 well-trained rowers performed paired 2000-m rowing ergometer trials under 3 double-blinded conditions: (1) 0.3 grams per kilogram of body mass (g/kg BM) acute bicarbonate; (2) 0.5 g/ kg BM daily chronic bicarbonate for 3 d; and (3) calcium carbonate placebo, in semi-counterbalanced order. For 2000-m performance and [HCO3 -], we examined differences in effects between conditions via pairwise comparisons, with differences interpreted in relation to the likelihood of exceeding smallest worthwhile change thresholds for each variable. We also calculated the within-subject variation (percent typical error). Results: There were only trivial differences in 2000-m performance between placebo (277 ± 60 W), acute bicarbonate (280 ± 65 W) and chronic bicarbonate (282 ± 65 W); however, [HCO3 -] was substantially greater after acute bicarbonate, than with chronic loading and placebo. Typical error for 2000-m mean power was 2.1% (90% confidence interval 1.4 to 4.0%) for acute bicarbonate, 3.6% (2.5 to 7.0%) for chronic bicarbonate, and 1.6% (1.1 to 3.0%) for placebo. Postsupplementation [HCO3 -] typical error was 7.3% (5.0 to 14.5%) for acute bicarbonate, 2.9% (2.0 to 5.7%) for chronic bicarbonate and 6.0% (1.4 to 11.9%) for placebo. Conclusion: Performance in 2000-m rowing ergometer trials may not substantially improve after acute or chronic bicarbonate loading. However, performances will be reliable with both acute and chronic bicarbonate loading protocols. ABSTRACT FROM AUTHOR

Effect of caffeine supplementation on repeated sprint running performance

This study examined the effects of 6 mg-kg-1 caffeine ingestion in team-sport players (N.=10) on repeated-sprint running performance (5 sets of 6 x 20 m) and reaction times, 60 min after caffeine or placebo ingestion. Methods. Best single sprint and total set sprint times, blood lactate and simple and choice reaction times (RT) were measured. Total sprint times across sets 1, 3 and 5 (departure every 25 s) were significantly faster after caffeine (85.49±5.55 s) than placebo (86.98±5.78 s) (P<0.05). Similarly, total sprint times across sets 2 and 4 (departure every 60 s), were significantly faster after caffeine (55.99±3.64 s) than placebo (56.77±3.74 s) (P<0.05). Significantly higher blood lactates were recorded in caffeine compared to placebo after set 3 (13.1±1.2 vs 10.3±1.4 mmolL ') (P<0.05) and set 5 (13.1±1.3 vs 103±1.6 mmol-L"1) (P<0.01). There were no significant effects on simple or choice RT, although effect sizes suggested improved post-exercise times after caffeine. Caffeine ingestion 60 min prior to exercise can enhance repeated sprint running performance and is not detrimental to reaction times. [PUBLICATION ABSTRACT]

Development and implementation of a novel measure for quantifying training loads in rowing : the T2minute method

Development and implementation of a novel measure for quantifying training loads in rowing: The T2minute method. J Strength Cond Res 28(4): 1172–1180, 2014—The systematic management of training requires accurate training load measurement. However, quantifying the training of elite Australian rowers is challenging because of (a) the multicenter, multistate structure of the national program; (b) the variety of training undertaken; and (c) the limitations of existing methods for quantifying the loads accumulated from varied training formats. Therefore, the purpose of this project was to develop a new measure for quantifying training loads in rowing (the T2minute method). Sport scientists and senior coaches at the National Rowing Center of Excellence collaborated to develop the measure, which incorporates training duration, intensity, and mode to quantify a single index of training load. To account for training at different intensities, the method uses standardized intensity zones (T zones) established at the Australian Institute of Sport. Each zone was assigned a weighting factor according to the curvilinear relationship between power output and blood lactate response. Each training mode was assigned a weighting factor based on whether coaches perceived it to be “harder” or “easier” than on-water rowing. A common measurement unit, the T2minute, was defined to normalize sessions in different modes to a single index of load; one T2minute is equivalent to 1 minute of on-water single scull rowing at T2 intensity (approximately 60–72% V[Combining Dot Above]O2max). The T2minute method was successfully implemented to support national training strategies in Australian high performance rowing. By incorporating duration, intensity, and mode, the T2minute method extends the concepts that underpin current load measures, providing 1 consistent system to quantify loads from varied training formats.

Effects of ingesting low glycemic index carbohydrate food for the sahur meal on subjective, metabolic and physiological responses, and endurance performance in Ramadan fasted men

To investigate the effect of low glycemic index (LGI) carbohydrate meal on subjective, metabolic and physiological responses, and endurance performance in the Ramadan fasted state.

'Wide-awake drunkenness'? Investigating the association between alcohol intoxication and stimulant use in the night-time economy

Aims: We tested whether patrons of the night-time economy who had co-consumed energy drinks or illicit stimulants with alcohol had higher blood alcohol concentration (BAC) levels than patrons who had consumed only alcohol. Design: Street intercept surveys (n=4227) were undertaken between 9 p.m. and 5 a.m. over a period of 7 months. Setting: Interviews were undertaken with patrons walking through entertainment precincts, queuing to enter venues or exiting venues in five Australian cities. Participants: The response rate was 92.1%; more than half the study sample was male (60.2%) and the median age was 23 years (range 18-72). Measurements: Data were collected on demographics, length of drinking session, venue types visited, types and quantity of alcohol consumed and other substance use. A BAC reading was recorded and a subsample of participants was tested for other drug use. Findings: Compared with the total sample (0.068%), illicit stimulant consumers (0.080%; P=0.004) and energy drink consumers (0.074%; P<0.001) had a significantly higher median BAC reading, and were more likely to engage in pre-drinking (65.6, 82.1 and 77.6%, respectively, P<0.001) and longer drinking sessions (4, 5 and 4.5 hours, respectively, P<0.001). However, stimulant use was not associated independently with higher BAC in the final multivariable model (illicit stimulants P=0.198; energy drinks P=0.112). Interaction analyses showed that stimulant users had a higher BAC in the initial stages of the drinking session, but not after 4-6 hours. Conclusions: While stimulant use does not predict BAC in and of itself, stimulants users are more likely to engage in prolonged sessions of heavy alcohol consumption and a range of risk-taking behaviours on a night out, which may explain higher levels of BAC among stimulants users, at least in the initial stages of the drinking session.

Web-based alcohol screening and brief intervention for university students: a randomized trial

IMPORTANCE: Unhealthy alcohol use is a leading contributor to the global burden of disease, particularly among young people. Systematic reviews suggest efficacy of web-based alcohol screening and brief intervention and call for effectiveness trials in settings where it could be sustainably delivered. OBJECTIVE: To evaluate a national web-based alcohol screening and brief intervention program. DESIGN, SETTING, AND PARTICIPANTS: A multisite, double-blind, parallel-group, individually randomized trial was conducted at 7 New Zealand universities. In April and May of 2010, invitations containing hyperlinks to the Alcohol Use Disorders Identification Test-Consumption (AUDIT-C) screening test were e-mailed to 14,991 students aged 17 to 24 years. INTERVENTIONS: Participants who screened positive (AUDIT-C score ≥4) were randomized to undergo screening alone or to 10 minutes of assessment and feedback (including comparisons with medical guidelines and peer norms) on alcohol expenditure, peak blood alcohol concentration, alcohol dependence, and access to help and information. MAIN OUTCOMES AND MEASURES: A fully automated 5-month follow-up assessment was conducted that measured 6 primary outcomes: consumption per typical occasion, drinking frequency, volume of alcohol consumed, an academic problems score, and whether participants exceeded medical guidelines for acute harm (binge drinking) and chronic harm (heavy drinking). A Bonferroni-corrected significance threshold of .0083 was used to account for the 6 comparisons and a sensitivity analysis was used to assess possible attrition bias. RESULTS: Of 5135 students screened, 3422 scored 4 or greater and were randomized, and 83% were followed up. There was a significant effect on 1 of the 6 prespecified outcomes. Relative to control participants, those who received intervention consumed less alcohol per typical drinking occasion (median 4 drinks [interquartile range {IQR}, 2-8] vs 5 drinks [IQR 2-8]; rate ratio [RR], 0.93 [99.17% CI, 0.86-1.00]; P = .005) but not less often (RR, 0.95 [99.17% CI, 0.88-1.03]; P = .08) or less overall (RR, 0.95 [99.17% CI, 0.81-1.10]; P = .33). Academic problem scores were not lower (RR, 0.91 [99.17% CI, 0.76-1.08]; P = .14) and effects on the risks of binge drinking (odds ratio [OR], 0.84 [99.17% CI, 0.67-1.05]; P = .04) and heavy drinking (OR, 0.77 [99.17% CI, 0.56-1.05]; P = .03) were not significantly significant. In a sensitivity analysis accounting for attrition, the effect on alcohol per typical drinking occasion was no longer statistically significant. CONCLUSIONS AND RELEVANCE: A national web-based alcohol screening and brief intervention program produced no significant reductions in the frequency or overall volume of drinking or academic problems. There remains a possibility of a small reduction in the amount of alcohol consumed per typical drinking occasion. TRIAL REGISTRATION: anzctr.org.au Identifier: ACTRN12610000279022.

Typology of alcohol consumers in five Australian nighttime entertainment districts

INTRODUCTION AND AIMS: Understanding how types of alcohol consumers differ is important for public policy targeted at reducing adverse events. The aims of the present study were to identify typologies of alcohol consumers in Australian nighttime entertainment districts based on risk factors for harm and to examine variation between the identified groups in drinking setting and harms. DESIGN AND METHODS: Street-intercept surveys were conducted with 5556 alcohol consumers in and around licensed venues in five Australian cities between November 2011 and June 2012. Latent class analysis identified groups based on age and sex, and blood alcohol concentration, pre-drinking, energy drink use and illicit drug use during that night. RESULTS: Four classes were identified: general patron group (33%), young pre-drinker group (27%), intoxicated male pre-drinker group (31%) and intoxicated illicit drug male group (9%). The proportion of the general patron group interviewed decreased over the night, while the other groups increased (particularly in regional cities). As compared with the general patron group, the remaining three groups reported increased odds of being involved in aggression and any alcohol-related injuries in the past 3 months, with highest rates of harm amongst the intoxicated illicit drug male group. DISCUSSION AND CONCLUSIONS: Alcohol consumers in nighttime entertainment districts are not a homogeneous group. One-third have a low likelihood of risky consumption practices; however, representation of this consumer class diminishes throughout the night. Elevated harms amongst groups characterised by certain risk factors (e.g. pre-drinking and illicit drug use) emphasise the importance of addressing these behaviours in public policy.